OVERDENTURES
INDIAN DENTAL ACADEMY
Leader in continuing dental education
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INTRODUCTION:
Preventive Prosthodontics emphasizes the
importance of any procedure that can delay or
eliminate the futur...
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DEFINITION:
G P T 1999,
1. Overdenture is defined as a removable partial
denture or a complete denture that covers and r...
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He artwe ll,
A tooth supported complete denture is a
dental prosthesis that replaces lost or missing
natural dentition a...
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History
The overdenture prosthesis constructed over existing
teeth or tooth structure is not a new concept in a technica...
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Since that convention, many more than hundred
journal articles on the retention of roots/teeth to
support a complete den...
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In 1952, the article by Rehn advocated the
retention of a single front tooth for denture
support.
In 1958, Miller report...
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The Gerber series of root cap attachments was
developed in 1954 and for 20 years, clinically
successful hybrid prosthesi...
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RATIONALE OF OVERDENTURES:
Retention of any tooth for an overdenture preserves
a portion of one of the major sensory in...
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Studies show that the natural anterior teeth
give more discreet sensory input, but posterior
teeth should also be retai...
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Fromthe physiologic view point the rationale for
preserving tooth roots are:
1.SENSITIVITY OF ANTERIORTEETH:
Sensory in...
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Kawamura (1964), Grossman (1964), and
Grossman and associates (1965) agreed that
the sensitivity in the anterior part o...
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2. DIMENSIONAL PERCEPTION:
Dimensional perception is the discrimination
of the different thickness of objects between t...
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3. CANINE RESPONSE:
Kruger and Michel (1962) said that the
canines have more neurons than any other
teeth. So, it acts ...
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4. DIRECTIONAL SENSITIVITY
Jerge (1963, 1965) reported that the receptors
in the periodontal ligament were directionall...
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5. PROPRIOCEPTION ANDSALIVARY
SECRETION:
Kapur and Collister (1970) studied food texture
discrimination and concluded t...
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6. PERCEPTION OF NONVITAL TEETH:
The majority of natural teeth used to support
overdentures are devitalized and treated...
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8. DECREASE OF PERCEPTION IN OLDER
INDIVIDUALS:
There is generalized decrease in
perception as age increases and the us...
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Advantages of overdentures
Equally effective and superior method of
treatment: In many situations, overdenture gives
be...
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Ease of maintenance: Repairs,
alterations or refitting of the overdenture can
be done readily in the same manner as wit...
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Esthetic excellence: The extensive selection of
artificial denture teeth and the many possible
arrangements for these a...
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Familiar Procedures: The procedure used are
similar to those used for conventional complete
dentures.
Ease in making me...
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Less trauma to the supporting tissues: The hard
tooth surface of the retained teeth supports the
dentures and inhibits ...
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Possibility of using attachments or soft
liners: This is done when soft tissue or bony
protuberances necessitate consid...
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Conversion to complete denture: The
tissue coverage and border extensions are
usually the same for overdentures as for
...
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Ease in Cleaning: All surfaces of the
abutment are accessible to cleaning, and the
denture being removable is easier to...
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Disadvantages of overdentures
The overdenture treatment is more expensive
than conventional denture treatment due to th...
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If the patient does not keep the retained roots or
teeth and the overdenture clean, caries and
periodontal disease may ...
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Indications:
Younger the patient greater the indication
In situations where retention is difficult to
obtain
a. Xerosto...
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When pronounced vertical overlap is required to
produce the desired esthetic result.
Unilateral overdenture can be give...
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Contraindications:
Uncooperative: Under motivated patients
Psychologically some patient cannot accept
removable prosthe...
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Contraindications for Endodontically involved teeth
Contraindications for periodontally involved teeth
• Class III Mobi...
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Clinical evaluation
The examination includes: Patient history, Study
casts, clinical examination, and Radiographs. It i...
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They also help in determining the amount of tooth
reduction required, the types of coping and often the
types of attach...
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Diagnosis includes: Clinical evaluation and
selection of abutments, abutment location, bone
support, proximal space bet...
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TREATMENT PLANNING:
The patient who has only few retainable natural
teeth may present difficult treatment questions for...
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The treatment planning include evaluation of all
potential abutments for:
• Periodontal status
• Endodontic status
• Ca...
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PERIODONTALSTATUS:
It is best to select abutments that are in an
acceptable state of periodontal health but,
often it i...
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Extreme oral neglect
Periodontal probing
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Periodontal surgery
Splinting done
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A common periodontal requisite with overdenture
abutment teeth is that an adequate zone of
attached gingival is mandato...
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ENDODONTIC CONSIDERATIONS:
There are mainly two advantages,
• The crown-root ratio can be made more favorable
• The red...
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CARIESMANAGEMENT:
The presence of high caries index and the
situation that will create a caries environment
are the dev...
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POSITIONALCONSIDERATIONS:
1. Preference for anterior over posterior teeth
because alveolar ridge of anterior teeth appe...
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3. The upper anterior teeth should be retained if
opposed by natural lower anterior teeth to
prevent the destruction of...
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Types of overdentures
I. Overdentures for congenital and acquired defects:
Many patients with congenital and acquired d...
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Oligodontia
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Class III Patient with missing teeth
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Patient with eroded teeth
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II. Transitional overdentures:
A Transitional or interim overdenture is made
from an existing removable partial denture...
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Advantages:
1. Less expensive
2. Smooth transition
3. Minimal interference with function and appearance
Disadvantages
1...
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Conversion using patient’s teeth
The patient derives a tremendous psychological
boost by having his teeth removed, but ...
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Posterior teeth arranged and
tooth to be retained is
prepared
Resin teeth are hollow
ground
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Hollow ground Canines placed
Stone matrix formed
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Canines are reduced
Incisors are extracted
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1.Denture base ready 2. Stone matrix placed
3. Prepared teeth 4. Teeth joined
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Completed Transitional overdenture
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III. Immediateoverdentures
An immediate overdenture is an overdenture
constructed for insertion immediately after the r...
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Impression tech no 1
Base plate wax adapted
Resin tray prepared
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Impression tech no 2
Impression with rubber
base imp material
Alginate impression over
the rubber base
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Impression tech no 3
Impression of edentulous area made in modeling plastic
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Impression is examined
Occlusal rims and
base plates
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Occlusal records made
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Casts secured on the articulator
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Replacement teeth are
positioned
Anterior teeth are
arranged
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Canine Prepared
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Resin tooth is hollow ground and placed
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Tooth indexing is done
Alginate impression of cast in flask
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Abutment height is measured on the cast and in the mouth
Tooth colored acrylic resin is sifted in the hollow
tooth
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Overdentures are ready
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Canines prepared and
remaining teeth extracted
Overdentures placed
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Disclosing wax is used
Interferences are reduced
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Tooth colored
autopolymerizing resin is
used for final seating of
the overdenture
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IV. Remote overdentures
A remote overdenture is an overdenture other
than transitional or immediate. It is usually
cons...
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Metal base overdentures:
A metal base overdenture is complete denture
with a cast metal base that is supported and
stab...
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Metal base Overdenture
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V. Removable partial denture:
A superior removable partial overdenture can
be made for may patients by reducing some
of...
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Removable partial overdenture fabricated on three
incisor teethwww.indiandentalacademy.com
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VI. Implant overdentures
A wide variety of implant types and procedures have
been used with an overdenture as the means...
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DOWEL DESIGNS
There are mainly 5 categories:
1. Customized cast dowels
2. Prefabricated resin patterns
3. Prefabricated...
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1.CUSTOMIZEDCAST DOWELS
When a dowel and coping are waxed together and
cast as a unit the discrepancy is the same as wh...
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2. PREFABRICATEDRESIN PATTERNS
The prefabricated dowel patterns are provided
with a matched set of burs for preparing t...
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3.PREFABRICATEDMETAL DOWELS
The prefabricated metal dowels have a big
advantage over the two previous systems because o...
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4.THREADEDDOWELS
Threaded dowels provide mechanical fixation in
addition to cementation. The VK and Kurer
systems offer...
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CLASSIFICATION OF OVERDENTURES
Heartwell:
I . Noncoping
II. Coping
III.Attachments
I. NONCOPING OVERDENTURES:
Selected ...
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II.COPING OVERDENTURES:
Coping Types
A coping fitted to a prepared abutment is called a
primary coping. The sleeve, or ...
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1. Long Copings (6-8 millimeters for vital teeth):
The long coping is an excellent restoration,
applicable to many over...
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2. Medium Copings (4-6 millimeters for vital and
non-vital teeth):
Medium sized copings may be used with vital teeth
wh...
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Abutment preparations
for medium copings
Medium copings
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With bar attachments To engage plunger
Studs cantilevered
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3. Medium short copings (2-4 mm for nonvital
teeth):
Medium short copings are indicated for non-vital teeth;
where a mo...
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4. Short Copings (1-2 millimeters for non-vital
teeth):
Short copings are fabricated to conform to the
curvature of the...
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III. Overdenture with Attachments:
The attachments essentially increase the crown-
root ratio and then torque. Or apply...
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ATTACHMENTS FOR OVERDENTURES
The ultimate objective of the prosthetic service is
to return the patient to as near a nor...
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BASIC PROSTHETIC DESIGN
It is important to realize that the causes of failure
inherent in the complete denture prosthes...
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Availability of the proprioceptive elements in the
attachment retained overdenture permits use of
gnathologic procedur...
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TOOTH PREPARATION
Tooth preparation varies with the type of support to be
provided. If there is sufficient tooth struc...
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The coping is waxed to a minimal occlusal
thickness of 1 mm with the exception of the bulk of
the inlay seat.
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TELESCOPE CROWNS:
The telescope crown is a prosthodontic retainer for a
fixed or removable prosthesis and usually cons...
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TELESCOPE OVERDENTURE:
The telescoped overdenture is an excellent alternative to
routine complete dentures. But what e...
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Advantages:
1. Conserve the alveolar ridge
2. Provide support and often retention
3. Retains some natural propriocepti...
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A Telescopic Overdenture Treatment Procedure:
Following is a case of advanced periodontal
disease and extensive breakd...
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Patient with extreme
dental neglect
Abutments are sectioned
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Preliminary endodontic
therapy was carried out
Abutment tooth are roughly
prepared and hopeless
roots sectioned
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Hopeless tooth and roots
removed
Periodontal surgeries
carried out, interim
dentures are very
important at this stage
...
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Tissues have healed and
matured final preparation of
tooth is done now
After healing, the preparations were modified t...
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A chamfer, or small shoulder with a beveled
marginal preparation, is prepared. This marginal
preparation is determined...
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Completed castings ready for
cementation. Long copings
for retention and stability and
short copings for support and
s...
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Master casts articulated
with accurate
interocclusal records
Coping undercuts are
blocked out with plaster
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A metal framework with
a horseshoe like major
connector was fabricated
on a refractory model
Resin denture teeth
were ...
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Completed overdenture
Secondary copings
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A resin secondary coping of a telescoped
overdenture does have some advantages over a
metal secondary coping particula...
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Relining and/or Rebasing
As the alveolar ridges resorb, the overdenture will begin
to rock and direct damaging lateral...
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ATTACHMENTS:
Bar compared to stud fixation
The splinting of two or more teeth with a bar
produces stability similar to...
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With bar units and joints, many times the bar
splints in more than one plane. Instead of the
prosthesis moving one too...
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ATTACHMENTS CAN BE CLASSIFIED
ACCORDING TOSHAPE, DESIGN, AND
PRIMARY AREA OF USE AS FOLLOWS:
(Mensor)
Coronal
1. Intra...
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Accessory
5. Auxiliary attachments
a. Screw units
b. Pawl connectors
c. Bolts
d. Stabilizers/balancers
e. Interlocks
f...
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The various attachment systems have been organized in a
compendium known as the EM attachment selector, which
presents...
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STUD(PRESSURE BUTTON) ATTACHMENTS:
Most of the stud-type attachments can be considered
to be "snap fasteners" and are ...
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RESILIENT STUDS
Resilient attachment systems are selected to perform
a compensatory service and to act as a safety val...
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When the mandibular appliance opposes a natural
dentition, some provision should be made for
movement so that maximal ...
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The retained root with an attachment offers
retention and positional or directional orientation
for the appliance. Whe...
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When to Use a Resilient Stud?
A resilient attachment permits the tissue to compress
slightly before any load is transm...
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When to use a non Resilient stud Attachment ?
A non resilient attachment will not allow vertical
movement (however it ...
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Some Stud Attachments:
1. Dalla Bona
2. Intrafix
3. Ancrofix
4. Gerber
5. Gmur
6. Rotherman
7. Huser
8. Schubiger
9. C...
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The GerberAttachment
The Gerber stud system is a versatile stud attachment
used routinely. It consists of a male post ...
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The male post consists of two
parts - a threaded base,
which is soldered to the
diaphragm of a coping, and a
removable...
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Convenient tools are also
used in the fabrication -
female screwdriver, male
screwdriver, paralleling
mandrel, heating...
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Step-by-Step Technique:
1. All treatments must start with a thorough oral
examination. This examination should include...
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4. All the teeth are reduced to
one to two mm above the
gingiva
5. Endodontics is performed
6. Partial preparation of ...
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10.Insert the interim overdenture with a soft relining material
11.After several weeks of healing, complete endodontic...
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13.Master cast with
removable dies
14.Copings waxed on
individual dies shaped
to conform to the
alveolar ridges. Resin...
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15.Position the finished
castings on the cast (lock
them together with Duralay);
invest and solder them to
form a spli...
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17.Position the male attachment on the coping. Consider
the following factors when determining the position of the
mal...
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18.Lock the cast on the
surveying table. Loosen the
male sleeves and Place in
the paralleling mandrel.
Find the most
a...
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20. Male sleeve is being
removed
21. Male stud sticky
waxed to the coping
with sleeve removed
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22.Screw the soldering cornal
onto the threaded base. It
acts as an extension arm
for the screw to aid in
soldering
23...
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24. Finished copings with
attachments assembled and
soldered, positioned on the
abutments
25.Take an accurate muscle
t...
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26. 3-4 thickness of x - ray
foils are adapted to all
copings for spacing.
27. Block out all undercuts
around the foil...
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28.Place a small amount
of Vaseline inside
each female then
snap it (with its
copper shim) onto the
male
29.Paint a th...
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30.Design the framework
with a major connector for
support and a minor
connector for the acrylic
denture base. Fabrica...
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32.Females locked inside. All
excess plaster and resin is
removed. Use the female
screwdriver to disassemble
the femal...
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Cement the copings onto the roots and insert
the overdenture
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Non-Resilient Gerber
The non-resilient Gerber attachment technique is
similar to that described above but with one
exc...
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Maintenance Consideration
Relining or Rebasing
Alveolar resorption will eventually cause the
denture to rock about the...
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Remove the internal
parts of the female with the
female screwdriver.
Carefully set aside all
internal parts to be
reas...
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Grind out several
millimeters of the acrylic
resin within the female
recess. Place the female
attachments (with their
...
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Male relining jig
Insert the special
male relining jigs
(transfer males) into
the females until a
definite snap is fel...
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The set cast, with the overdenture, is
articulated to a special relining jig. The
relining or rebasing procedure is si...
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Advantages of the Gerber attachment
1. It provides adequate retention, stability and
support.
2. Its retention is ligh...
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Disadvantages of Gerber attachment
1. It is a complex attachment and maintenance
problems are relatively common. The m...
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Dalla Bona Attachment
The Dalla Bona is a simple stud attachment making an
excellent overdenture attachment available ...
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Dalla bona attachments on
two cuspids makes it
excellent overdenture
arrangement
Spherical Bona with
undercut for rete...
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Male is a solid stud, female
is a single component with
retentive lamellae. A clear
Teflon ring covers the
female lame...
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Cylindrical Dalla Bona
The cylindrical male post has parallel walls
without an undercut. The female lamella fits
snugl...
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Spherical Dalla Bona
The spherical Dalla Bona is similar to the
cylindrical, but the male post is spherical. This
sphe...
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Advantages
1. Their overall length varies between 3.3 millimeters
(cylindrical), to 3.7 millimeters (spherical), so it...
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Disadvantages
1. The retentive action of the female is very stiff and
difficult to adjust.
2. The collar that retains ...
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Spherical Dalla Bona Treatment
Diagnosis, treatment and management using the
Dalla Bona are very similar to that descr...
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Casts with the removable
dies are fitted with the
resin dowel pattern
coping pattern is waxed
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To improve the soldering
procedure, cut a ditch in the
diaphragm of the coping.
This ditch aids the flow of
solder und...
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Add a short strip of round
wax to one side of the
waxed base. This will
produce flame vent holes
within the investment...
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The coping substructure
is withdrawn from the
abutments with an
accurate muscle trimmed
impression to become
integral ...
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Block out all coping
undercuts with plaster
The casts are articulated on
an appropriate articulator with
accurate occl...
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The Rotherman Attachment
The Rotherman is another excellent stud attachment.
The Rotherman consists of a solid stud (t...
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The Rotherman anchorage
has a short solid stud( non
resilient right, resilient left)
and a double armed clasp.
The cla...
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The male features a definite undercut on just one
side of the cylinder. A scribe line on the occlusal
indicates the po...
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Ancrofix Attachment
The Ancrofix is similar to the spherical Dalla Bona
with a rounded male post providing the undercu...
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Ancrofix stud
Male stud and female
with Teflon sleeve
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BAR ATTACHMENTS
As the name suggests, bar attachments consist of a
metal bar that splints two or more abutments and a
...
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Types of BarAttachments
Bar units
Bar joints
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The Bar Unit
This bar has parallel walls providing rigid fixation
with frictional retention. It can be used for
retent...
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The Bar Joint
The action of this attachment provides rotational or
vertical movement. In other words, it is a stress
b...
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The Dolder Bar
An ideal bar attachment is the Dolder bar. It is well
designed for splinting two or more abutments to
p...
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Dolder bar joint
The pear shaped bar joint is designed to provide vertical and
rotational action so it is indicated wh...
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Typical Dolder bar Treatment:
• Endodontics, extractions and periodontal surgery
were completed prior to starting the ...
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Diamond bur is used to
prepare the abutments with
a bevel or chamfer margin. X
indentation is made.
The copings can be...
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Fabricate a customized
impression tray on the
study cast. Prepare holes
in the tray over the root
preparations. The
im...
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Plastic dowels used as
dowel patterns
Short coping patterns
are waxed to conform
to curvature of the
alveolar ridge
ww...
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The copings are finished, but
are left with a short section of
the sprue on each casting
which will be removed later.
...
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Cut the bar to fit between
the copings. The bar
should be positioned
slightly lingual
Connect the bar to the
copings (...
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Retentive shell is cut
and fit over the bar
Shell is modified for better
retention
Method of modification
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The metal spacer is
positioned over the bar and
the retentive shell is
snapped on the bar
securing the spacer.
Space m...
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Block out all undercuts
around the copings with
plaster and cover the
flanges of the retentive
shell
Consequence of
ex...
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With a small brush,
sparingly paint a semidry
mix of auto polymerizing
acrylic resin (such as
Duralay) to cover the en...
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Use the stone index to
reposition the anterior
teeth and complete the
denture set-up
The denture is waxed,
festooned, ...
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Cement the
Dolder
bar/coping
assembly into
position. The
overlay denture
is inserted for
use.
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Overdenture Function
Let us now consider the function of this
overdenture. Freedom for vertical movement,
provided by ...
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At rest, the overdenture sits
passively only on the
alveolar tissues. A space is
present between the bar-
coping assem...
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Adjusting Retention:
Retention of the overdenture is easily increased or
decreased by adjusting the flanges of the she...
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1. With a small round bur, carefully remove the acrylic around the
shell, and remove the shell. It will be used later....
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5. The impression is
poured with model stone.
6. The cast with the
overdenture attached is
mounted in a relining jig.
...
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7.The overdenture is
removed from the cast
leaving a reproduction of
the soft tissue, the copings
and Dolder bar.
8. T...
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9. The cast is now treated as if you are fabricating a new
overdenture i. e,
• Place three to four layers of X-ray foi...
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The Dolder Bar Unit
The Dolder bar unit is an excellent attachment
when an all tooth supported, non rotational
acting ...
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The Hader Bar System
The Hader system is an excellent bar attachment.
Similar to the customized bar, the Hader system
...
201
Components of the Hader system are (from left to
right).
• Plastic bar pattern (1.8 mm diameter, vertical height
5.7 m...
202
Hader Bar Technique
• Take an impression of the prepared abutments,
pour a cast and trim the dies as you would any
bar...
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7.The completed
substructure pattern
is sprued, invested,
cast and finished.
8.Seat the
substructure on
the cast for
c...
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9. Position modeling
riders on the bar where
clips will attach. These
riders are removed
after the prosthesis is
fabri...
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11.When the overdenture
is finished, remove the
modeling riders with
pliers or a sharp
instrument
12. Use the special
...
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13.The denture is now
ready for use
Metal clips for retention
If a metal rider is
preferred, it should be
incorporated...
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Advantages of the Hader System
1. The plastic bar pattern is easily adapted to differences in
the surface of the gingi...
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AUXILLARY ATTACHMENTS
In addition to bars and studs, other attachment
systems are applicable for overdenture
prosthese...
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SCREWS:
Schubiger Screw Attachment
An excellent screw attachment often used in
overdenture technique is the Schubiger....
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Plunger-Type Attachments
Auxiliary retention for an overlay prosthesis is
often desirable and it may be added to vario...
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Review of literature
Paul A. Miller ( 1958) gave special
emphasis on preservation of tissues with
support of artificia...
212
Dolder E. J. in 1961 advocated the bar joint
denture. The denture is adapted primarily to the
situation with which onl...
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Robert J. Crum and R. J. Loiselle
(1972) in his review of literature reveal that
discrete sensitivity that exists in t...
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Merrill C. Mensor (1973) advocated the use of
E M attachment selector which consists of 8.5
by 11 inch color coded sel...
215
Joseph T. Quinlivan (1974) said that retention is
a problem for overlay dentures over simple
copings when only two tee...
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Wayne R. frantz (1975) described the
construction of tooth supported dentures where
the natural tooth was utilized and...
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A. B. Warren and A. A. caputo (1975)
conducted a study to determine and compare
the transfer of forces to the alveolar...
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H H Thayer and A A Caputo (1977) provided the
following guidelines in the selection of specific
designs for overdentur...
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3. The forces on the Dolder bar produce stress
directed more apically than that from the Zest
anchor. Since this force...
220
Merrill C. Mensor (1978) said that when selecting
an attachment it is essential to consider the skill of
the dentist –...
221
Robert J. Crum and George E. Rooney (1978)
conducted a 5 year clinical study to determine
the amount of bone loss in t...
222
H. H. Thayer and A. A. Caputo (1979)
concluded that
a) The more retentive tissue bar and extra
coronal attachments pro...
223
Gary D.Derkson and Michael Macentee ( 1982)
conducted a study to observe the therapeutic
effect of 0.4% stannous fluor...
224
Conclusion:
To conclude it would not be a repetition to say
that overdenture is a preventive dentistry
concept which h...
225
1) Selection of patient
2) Treatment planning
3) Preparation of the mouth
4) Execution of the prosthodontic work
5) Ma...
226
References
1. Brewer AA, Morrow RM: Overdentures, ed 2. St
Louis, CV Mosby, 1980.
2. Crum RJ, Rooney GE Jr: Alveolar b...
227
6. Quinlivan JT: An attachment for overlay dentures. J
Prosthet Dent 1974;32:256-261.
7. Thayer HH, Caputo AA: Occlusa...
228
12.Wayne R Frantz: The use of natural teeth in
overdentures. J Prosthet Dent 1975;34:135-140.
13.A B Warren and Caputo...
www.indiandentalacademy.com 229
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Overdenture / orthodontic straight wire technique

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Transcript of "Overdenture / orthodontic straight wire technique"

  1. 1. OVERDENTURES INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com 1www.indiandentalacademy.com
  2. 2. 2 INTRODUCTION: Preventive Prosthodontics emphasizes the importance of any procedure that can delay or eliminate the future Prosthodontic problems. The overdenture is a logical method for the Dentist to use in preventive Prosthodontics. It is further emphasized that alveolar bone with its overlying mucosa was never intended to receive the full force of complete denture. So, what is this overdenture? www.indiandentalacademy.com
  3. 3. 3 DEFINITION: G P T 1999, 1. Overdenture is defined as a removable partial denture or a complete denture that covers and rests on one or more remaining natural teeth, the roots of natural teeth, and/or dental implants. 2. A prosthesis that covers and is partially supported by natural teeth, natural tooth roots, and/or dental implants – called also Overlay denture, overlay prosthesis, superimposed prosthesis. www.indiandentalacademy.com
  4. 4. www.indiandentalacademy.com 4
  5. 5. 5 He artwe ll, A tooth supported complete denture is a dental prosthesis that replaces lost or missing natural dentition and associated structures of the maxilla and/or mandible and receives partial support and stability from one or more modified natural teeth. www.indiandentalacademy.com
  6. 6. 6 History The overdenture prosthesis constructed over existing teeth or tooth structure is not a new concept in a technical approach to a prosthodontic problem. Its use dates back over 100 years. In 1861, Barker reported on the proceedings of the American Dental convention in New Haven, Connecticut. Dr. Butler, Dr. Roberts, Dr. Atkinson, Dr. Sutton and Dr. Hayes participated in a symposium entitled – “Surgical preparation of the mouth for artificial dentures – should the roots would enable fabrication of complete dentures superior to that obtained after extraction of all roots. Hayes reported the results of fabricating a complete denture over two roots in the maxillary arches and 12 years later, they were still in place contributing to the comfort of the patient.www.indiandentalacademy.com
  7. 7. 7 Since that convention, many more than hundred journal articles on the retention of roots/teeth to support a complete denture have appeared. In 1945, Black of Louisville, Kentucky provided complete denture for a 14-year old girl with a congenital absence of the permanent teeth. Four maxillary and four mandibular teeth were retained and crowns were fitted to the molars. In 1972, 27 years later the mandibular deciduous molars were still intact supporting a complete mandibular overdenture. During the Second World War, many dentists in a military service used overdentures in the treatment of inadequate or mutilated dentitions. Boos reported such a treatment in the July 1948 issue of the Dental Digest. www.indiandentalacademy.com
  8. 8. 8 In 1952, the article by Rehn advocated the retention of a single front tooth for denture support. In 1958, Miller reported that retention of a few teeth under complete dentures allowed the weak teeth to regain healthy status. This foresight was of prime importance in convincing the profession that the overdenture was a superior treatment modality. In 1969, Lord and Teel reported 7 years of successful treatment with overdentures. www.indiandentalacademy.com
  9. 9. 9 The Gerber series of root cap attachments was developed in 1954 and for 20 years, clinically successful hybrid prosthesis have been fabricated with the Gerber attachments. As new materials and products such as plastic tooth material, soft liners, fluorides were introduced, the potential for this type of treatment increased materially. Methods were simplified and at present overdenture, treatment can be provided at a little additional cost over the conventional complete denture. www.indiandentalacademy.com
  10. 10. 10 RATIONALE OF OVERDENTURES: Retention of any tooth for an overdenture preserves a portion of one of the major sensory inputs i.e. input from the periodontal propioceptors, which contain information about the magnitude and direction of the occlusal forces as well as about the size and consistency of the food bolus. This along with the input of other receptors in the mouth, muscles, TMJ contribute to the overall response. The periodontal receptors input are also protective against occlusal overloading. Extraction of all teeth results in total loss of all input from periodontal ligament receptors; where as use of an overdenture preserves the sensory input.www.indiandentalacademy.com
  11. 11. 11 Studies show that the natural anterior teeth give more discreet sensory input, but posterior teeth should also be retained for overdentures whenever feasible even though their sensory input is lesser. It is also known that the retention of teeth for overdentures provide better sensory feed back regarding masticatory performance. Studies show that the use of an overdenture preserves alveolar bone, especially in the area of the retained teeth. In this area, resorption occurs very rapidly after extraction of teeth. www.indiandentalacademy.com
  12. 12. 12 Fromthe physiologic view point the rationale for preserving tooth roots are: 1.SENSITIVITY OF ANTERIORTEETH: Sensory input from the periodontal receptors is one of the major determinants of masticatory function, and the roots of the teeth offer more discrete discriminatory input than does the oral mucosa. Retention of natural teeth for an overdenture preserves some of the sensory input from the periodontal receptors, which is more precise than that able to be obtained from the oral mucosa. www.indiandentalacademy.com
  13. 13. 13 Kawamura (1964), Grossman (1964), and Grossman and associates (1965) agreed that the sensitivity in the anterior part of the mouth, particularly the periodontal ligament of the anterior teeth, tongue tip, and mucosa, was acute. There is a greater concentration of sensory receptors in the anterior part of the mouth (Kawamura, 1964), and these signals from the periodontal and mucosal receptors are important in controlling and determining biting force. www.indiandentalacademy.com
  14. 14. 14 2. DIMENSIONAL PERCEPTION: Dimensional perception is the discrimination of the different thickness of objects between the occlusal surfaces of the teeth. Kawamura and Watanabe (1960) found that patients with natural dentition could discriminate differences at the 2 mm range better than those with artificial dentures. These findings emphasized the importance of conservative procedures and the importance of the retention of natural teeth. www.indiandentalacademy.com
  15. 15. 15 3. CANINE RESPONSE: Kruger and Michel (1962) said that the canines have more neurons than any other teeth. So, it acts as very important proprioceptive organ which can lend support to the retention for the overdenture. www.indiandentalacademy.com
  16. 16. 16 4. DIRECTIONAL SENSITIVITY Jerge (1963, 1965) reported that the receptors in the periodontal ligament were directionally sensitive. He said that the receptors are arranged around a tooth in such a way as to respond to pressure regardless of the direction from which it is applied. Directional sensitivity is one of the most important elements in the interaction of the masticatory system. It means that the periodontal receptors have a functional individuality and that the relationship of the tooth to its periodontal ligament is highly important from a sensory standpoint. Therefore, teeth should be retained for use with an overdenture to preserve the directional sensitivity.www.indiandentalacademy.com
  17. 17. 17 5. PROPRIOCEPTION ANDSALIVARY SECRETION: Kapur and Collister (1970) studied food texture discrimination and concluded that the periodontal receptors played an indirect role in the masticatory salivary reflex by regulating the range and type of the masticatory stroke. They stated that absence of the periodontal ligament in denture wearers appeared to result in impairment of the mechanism regulating parotid gland stimulation during mastication. www.indiandentalacademy.com
  18. 18. 18 6. PERCEPTION OF NONVITAL TEETH: The majority of natural teeth used to support overdentures are devitalized and treated endodontically. Perceptual studies showed that vital and devitalized teeth had equal sensory input capabilities (Stewart, 1927; Adler, 1947). 7. PERCEPTION OF TEETH WITH REDUCED ALVEOLARSUPPORT: Often teeth selected for use with overdentures may have lost bone support. These studies showed that the tooth still had a proprioceptive input capability even though much of the bone support was lost.www.indiandentalacademy.com
  19. 19. 19 8. DECREASE OF PERCEPTION IN OLDER INDIVIDUALS: There is generalized decrease in perception as age increases and the use of an overdenture is an attempt to retain every possible sensory element at the time the patient may experience a generalized decrease in the sensory capacity. www.indiandentalacademy.com
  20. 20. 20 Advantages of overdentures Equally effective and superior method of treatment: In many situations, overdenture gives better service than alternative methods of treatment, especially in patients with congenital defects (oligodontia, microdontia, cleft palate etc.) and for class III patients with a prognathic jaw not amenable to surgical an orthodontic treatment. Simplicity of construction: The procedure used in constructing overdentures are the same as those for complete dentures, and the retained teeth or roots provide stability to the bases during registration of maxillomandibular records. Also they aid in determining the correct vertical dimension of occlusion and in proper tooth placement.www.indiandentalacademy.com
  21. 21. 21 Ease of maintenance: Repairs, alterations or refitting of the overdenture can be done readily in the same manner as with conventional complete dentures. Stability: Stability is comparable to that obtained with fixed or removable partial dentures and the retention of four abutments contributes greatly to this stability. Retention: Generally retention is excellent because of the better stability of overdentures.www.indiandentalacademy.com
  22. 22. 22 Esthetic excellence: The extensive selection of artificial denture teeth and the many possible arrangements for these aids in creating an esthetic effect. Open palate possible: The maxillary denture of many patients can be roofless if necessary, especially where anterior and posterior teeth are saved Reasonable cost: The time required for creating an overdenture and thus the cost can be less than for alternative procedures. www.indiandentalacademy.com
  23. 23. 23 Familiar Procedures: The procedure used are similar to those used for conventional complete dentures. Ease in making measurements: When teeth are retained for immediate overdentures, the vertical dimensions of occlusion can be maintained accurately. Ideal Occlusion: Esthetically acceptable occlusion can be provided. Excellent patient acceptance: This is attributable to the knowledge that the patient still has his own teeth. www.indiandentalacademy.com
  24. 24. 24 Less trauma to the supporting tissues: The hard tooth surface of the retained teeth supports the dentures and inhibits resorption of the residual ridge, which may occur when all the teeth are removed, and conventional complete dentures provided. Less soft tissue trauma also occurs. Stabilization of existing structures: Although tissues under a long span without tooth support may resorb, little change occurs at the site of retained teeth, thus maintaining the vertical dimensions and the lip support. Minimal adjustment: Little adjustment is required due to the stability and support provided to the overdenture by the retained teeth.www.indiandentalacademy.com
  25. 25. 25 Possibility of using attachments or soft liners: This is done when soft tissue or bony protuberances necessitate considerable relief of the denture and it is difficult to maintain a seal. Attachments or soft liners can be used. Transitional or training dentures: Even though the patient may loose the retained teeth or roots or both in a short time the overdenture is not only stable but also retentive for the period of use, but is also excellent for transitional or training in preparation for receiving a complete denture.www.indiandentalacademy.com
  26. 26. 26 Conversion to complete denture: The tissue coverage and border extensions are usually the same for overdentures as for complete dentures making it easy to compensate for the loss of one or all of the retained teeth. The spaces can be filled in or the dentures can be relined or rebased. Reversibility: When making overdentures over a complete natural dentition, it may be necessary to alter the existing teeth. Therefore, the procedure is reversible, and removal of denture puts the teeth back in their original states.www.indiandentalacademy.com
  27. 27. 27 Ease in Cleaning: All surfaces of the abutment are accessible to cleaning, and the denture being removable is easier to clean than a fixed partial denture. Proprioceptive response: There is more efficient neuromuscular coordination. Distribution of forces of mastication: Forces are distributed more uniformly over the roots and denture supporting tissues. Fewer post insertion problems: As compared a conventional complete dentures. www.indiandentalacademy.com
  28. 28. 28 Disadvantages of overdentures The overdenture treatment is more expensive than conventional denture treatment due to the endodontic therapy usually required and the subsequent restoration of the teeth with alloys or gold copings. Frequently teeth to be retained also need periodontal therapy. The overdenture is bulkier than the fixed 0r removable partial dentures. Many patients do not like any removable appliance and therefore may prefer a fixed partial denture. www.indiandentalacademy.com
  29. 29. 29 If the patient does not keep the retained roots or teeth and the overdenture clean, caries and periodontal disease may progress. Maintenance problems: • Copings may become loose • Attachment wear, loss and breakage •Alveolar ridge resorption • Overdenture breakage • Oral hygiene problems www.indiandentalacademy.com
  30. 30. 30 Indications: Younger the patient greater the indication In situations where retention is difficult to obtain a. Xerostomia b. Absence of alveolar residual ridge c. Loss of maxilla or partial loss of mandible d. Congenital deformity (i.e. Cleft palate) For patients with poor prognosis for complete dentures a. High palatal vault and ridge slope b. Poorly defined sublingual fold space c. In class III tongue patients d. Knife edge ridge www.indiandentalacademy.com
  31. 31. 31 When pronounced vertical overlap is required to produce the desired esthetic result. Unilateral overdenture can be given to provide good function and esthetics when a large amount bone and soft tissues have been lost on one side of the arch Patient with badly worn out teeth. When complete denture will be opposed by retained mandibular anterior teeth preventing combination syndrome. www.indiandentalacademy.com
  32. 32. 32 Contraindications: Uncooperative: Under motivated patients Psychologically some patient cannot accept removable prosthesis Mentally and physically compromised When patient cannot economically afford www.indiandentalacademy.com
  33. 33. 33 Contraindications for Endodontically involved teeth Contraindications for periodontally involved teeth • Class III Mobility • Uncorrectable soft tissue and osseous defects • Failure to establish sufficient zone of attached gingiva • Vertical fracture • Mechanical perforation of root • Broken instrument • Horizontal fracture of root below bony crestwww.indiandentalacademy.com
  34. 34. 34 Clinical evaluation The examination includes: Patient history, Study casts, clinical examination, and Radiographs. It is very difficult to make a correct diagnosis to determine if the overdenture is indicated for the patient or the problems can be solved by alternative techniques. This is ascertained by taking a proper history of the patient’s medical background and past dental history. The past dental history indicates the patients experience with previous removable appliances and his attitude towards the treatment. Study casts accurately mounted on an articulator show the occlusal relationship of the teeth and arches, the vertical spaces between arches and location of bony undercuts.www.indiandentalacademy.com
  35. 35. 35www.indiandentalacademy.com
  36. 36. 36 They also help in determining the amount of tooth reduction required, the types of coping and often the types of attachments that can be used for particular condition. Accurate study casts can also be used for fabrications of interim overdentures when necessary. Clinical examination includes examination of the entire oral cavity. All soft tissues are evaluated and teeth are evaluated thoroughly. Occlusal relationships are studied and periodontal and endodontic evaluation is carried out. Potential abutments are evaluated for mobility, crown root ratio etc. Radiographic examination is done to evaluate presence of pathological conditions, presence of retained roots, bone loss, root curvatures, root canals are noted. www.indiandentalacademy.com
  37. 37. 37 Diagnosis includes: Clinical evaluation and selection of abutments, abutment location, bone support, proximal space between abutments, number of teeth available, masticatory load and opposing dentition and the type/design of prosthesis required. www.indiandentalacademy.com
  38. 38. 38 TREATMENT PLANNING: The patient who has only few retainable natural teeth may present difficult treatment questions for the dentist. Johnston and associates (1965) stated that “a bridge is indicated whenever there are properly distributed and healthy teeth to serve as abutments, provided these have suitable crown-root ratio and that after radiographic, diagnostic cast and oral examinations seem capable of sustaining the additional load. When indicated, fixed partial dentures are treatment of choice. A few retainable teeth generally are scattered throughout the arch, and invariably they are involved periodontally with unfavorable crown-root ratios, the overdenture option should be considered.www.indiandentalacademy.com
  39. 39. 39 The treatment planning include evaluation of all potential abutments for: • Periodontal status • Endodontic status • Caries management • Positional considerations • Economics www.indiandentalacademy.com
  40. 40. 40 PERIODONTALSTATUS: It is best to select abutments that are in an acceptable state of periodontal health but, often it is necessary to use teeth that are less than ideal. Abutment should have minimum mobility, have adequate bone support and be amenable to any indicated periodontal treatment. Periodontal pockets, inflammation, bony defects and poor zone of attached gingiva must all be eliminated before commencing the treatment. www.indiandentalacademy.com
  41. 41. 41 Extreme oral neglect Periodontal probing www.indiandentalacademy.com
  42. 42. 42 Periodontal surgery Splinting done www.indiandentalacademy.com
  43. 43. 43 A common periodontal requisite with overdenture abutment teeth is that an adequate zone of attached gingival is mandatory. This can be accomplished with periodontal surgery utilizing either a free gingival graft or apically repositioning split thickness flap. This results in a band of attached gingiva adjacent to abutment tooth. It should be understood that reduction of clinical crown-root ratio will be favorable in reducing any existing mobility. www.indiandentalacademy.com
  44. 44. 44 ENDODONTIC CONSIDERATIONS: There are mainly two advantages, • The crown-root ratio can be made more favorable • The reduction crown provides for an interocclusal distance more favorable to placing the artificial tooth in an esthetically acceptable position. www.indiandentalacademy.com
  45. 45. 45 CARIESMANAGEMENT: The presence of high caries index and the situation that will create a caries environment are the devastating sequalae to improper overdenture patient selection. An active caries process can lead to a recurrence of in unprotected abutment teeth or gingival to coping margins and this can lead to failure of the overdenture. www.indiandentalacademy.com
  46. 46. 46 POSITIONALCONSIDERATIONS: 1. Preference for anterior over posterior teeth because alveolar ridge of anterior teeth appears to be more vulnerable to reduction compared to posterior alveolar ridge. 2. Two teeth in each quadrant presents an ideal situation in where stress is distributed over a rectangular area. Two canines and two second premolars present an ideal situation. The tripod is next most favorable form for support and stability. The use of two teeth in each arch or one tooth in one arch has met with satisfactory results. Morrow recommends to use isolated teeth as abutments because they return to healthy state readily and are easier for the patient to maintain hygiene. www.indiandentalacademy.com
  47. 47. 47www.indiandentalacademy.com
  48. 48. 48 3. The upper anterior teeth should be retained if opposed by natural lower anterior teeth to prevent the destruction of the anterior maxillary ridge when utilized in a maxillary overdenture. 4. Mandibular cuspids are most often utilized since they are usually last tooth to fall. ECONOMICS: Endodontic treatment, cast copings, attachments and overdenture itself may workout expensive, so economics of the patient should be considered. www.indiandentalacademy.com
  49. 49. 49 Types of overdentures I. Overdentures for congenital and acquired defects: Many patients with congenital and acquired defects cannot be treated successfully with orthodontic or surgical therapy, nor can they be treated with conventional procedures – either fixed or removable. However there has been a high degree of success in treating these patients with complete dentures over their existing teeth. The congenital defects most frequently treated with over dentures are: Cleft palate Micordontia Oligodontia Cleidocranial dystosis Class III patients with prognathic mandible. The acquired defects most frequently treated by this usually results from accidents, disease or misuse. www.indiandentalacademy.com
  50. 50. 50 Oligodontia www.indiandentalacademy.com
  51. 51. 51 Class III Patient with missing teeth www.indiandentalacademy.com
  52. 52. 52 Patient with eroded teeth www.indiandentalacademy.com
  53. 53. 53 II. Transitional overdentures: A Transitional or interim overdenture is made from an existing removable partial denture, the patients own teeth or from both. Frequently, the entire procedure can be done while the patient waits, or part of it can be done before the extraction visit. The objective is to do the most for the patients with the least of trauma. www.indiandentalacademy.com
  54. 54. 54www.indiandentalacademy.com
  55. 55. 55 Advantages: 1. Less expensive 2. Smooth transition 3. Minimal interference with function and appearance Disadvantages 1.Border extension, esthetics, occlusion, support and stability of the R.P.D. often are inadequate, particularly after many years of use, making satisfactory conversion difficult. 2.Weaker overdenture 3.Therefore, the converted prosthesis is considered as interim or temporary overdenture, to be replaced after a suitable transitional period. www.indiandentalacademy.com
  56. 56. 56 Conversion using patient’s teeth The patient derives a tremendous psychological boost by having his teeth removed, but leaving with them still in his mouth; even through they are in an overdentures. This is a more economical method. Pre op view www.indiandentalacademy.com
  57. 57. 57 Posterior teeth arranged and tooth to be retained is prepared Resin teeth are hollow ground www.indiandentalacademy.com
  58. 58. 58 Hollow ground Canines placed Stone matrix formed www.indiandentalacademy.com
  59. 59. 59 Canines are reduced Incisors are extracted www.indiandentalacademy.com
  60. 60. 60 1.Denture base ready 2. Stone matrix placed 3. Prepared teeth 4. Teeth joined www.indiandentalacademy.com
  61. 61. 61 Completed Transitional overdenture www.indiandentalacademy.com
  62. 62. 62 III. Immediateoverdentures An immediate overdenture is an overdenture constructed for insertion immediately after the removal of natural teeth. It may be used as an interim prosthesis. The immediate overdenture enables a dentist to use a simplified construction technique that allows flexibility in planning treatments as requirements change. Many times with good oral hygiene and regular professional supervision an immediate overdenture may have a long life. Sometimes, it can be a prognostic aid before a more comprehensive overdenture procedure. If prognosis is poor and response to treatment is poor and immediate denture can be converted into a serviceable complete denture. www.indiandentalacademy.com
  63. 63. 63 Impression tech no 1 Base plate wax adapted Resin tray prepared www.indiandentalacademy.com
  64. 64. 64 Impression tech no 2 Impression with rubber base imp material Alginate impression over the rubber base www.indiandentalacademy.com
  65. 65. 65 Impression tech no 3 Impression of edentulous area made in modeling plastic www.indiandentalacademy.com
  66. 66. 66 Impression is examined Occlusal rims and base plates www.indiandentalacademy.com
  67. 67. 67 Occlusal records made www.indiandentalacademy.com
  68. 68. 68 Casts secured on the articulator www.indiandentalacademy.com
  69. 69. 69 Replacement teeth are positioned Anterior teeth are arranged www.indiandentalacademy.com
  70. 70. 70 Canine Prepared www.indiandentalacademy.com
  71. 71. 71 Resin tooth is hollow ground and placed www.indiandentalacademy.com
  72. 72. 72 Tooth indexing is done Alginate impression of cast in flask www.indiandentalacademy.com
  73. 73. 73 Abutment height is measured on the cast and in the mouth Tooth colored acrylic resin is sifted in the hollow tooth www.indiandentalacademy.com
  74. 74. 74 Overdentures are ready www.indiandentalacademy.com
  75. 75. 75 Canines prepared and remaining teeth extracted Overdentures placed www.indiandentalacademy.com
  76. 76. 76 Disclosing wax is used Interferences are reduced www.indiandentalacademy.com
  77. 77. 77 Tooth colored autopolymerizing resin is used for final seating of the overdenture www.indiandentalacademy.com
  78. 78. 78 IV. Remote overdentures A remote overdenture is an overdenture other than transitional or immediate. It is usually constructed for insertion at sometime remote from the removal of hopeless natural teeth. The remote overdenture usually placed on well healed ridges usually after a period of satisfactory experience with an interim overdenture which may be transitional or immediate. Although remote overdentures can be entirely constructed of resin, metal bases are frequently used. www.indiandentalacademy.com
  79. 79. 79 Metal base overdentures: A metal base overdenture is complete denture with a cast metal base that is supported and stabilized by selected natural teeth with contours that are modified for the purpose by preparation and placement of copings. www.indiandentalacademy.com
  80. 80. 80 Metal base Overdenture www.indiandentalacademy.com
  81. 81. 81 V. Removable partial denture: A superior removable partial overdenture can be made for may patients by reducing some of the remaining teeth coronally so that the prosthesis can be fabricated over them. Tooth preparation Removable partial overdenturewww.indiandentalacademy.com
  82. 82. 82 Removable partial overdenture fabricated on three incisor teethwww.indiandentalacademy.com
  83. 83. 83 VI. Implant overdentures A wide variety of implant types and procedures have been used with an overdenture as the means of a final restoration. The osseointergrated approach of implants with its use of titanium metal and rather sophisticated techniques of placement has proven to be viable and worthy procedure. Although it is used mostly with fixed type of prosthesis, on occasion single fixtures are placed on each side of the midline and an overdenture is fabricated over fixture. www.indiandentalacademy.com
  84. 84. 84 DOWEL DESIGNS There are mainly 5 categories: 1. Customized cast dowels 2. Prefabricated resin patterns 3. Prefabricated metal dowels 4. Threaded dowels 5. Dowel systems www.indiandentalacademy.com
  85. 85. 85 1.CUSTOMIZEDCAST DOWELS When a dowel and coping are waxed together and cast as a unit the discrepancy is the same as when making an inlay and crown in the same casting. If the expansion for the coping were sufficient, the dowel would be oversized, the coping could not seat, and the dowel could fracture the root during either try-in or cementation because of the wedge effect and the hydrostatic pressure of the cement. This factor can be reduced by preparing cement -release groove down the long axis of the dowel. If the dowel were undersized, the coping would seat properly, but the dowel would be retained by cement only.www.indiandentalacademy.com
  86. 86. 86 2. PREFABRICATEDRESIN PATTERNS The prefabricated dowel patterns are provided with a matched set of burs for preparing the dowel space. The cross sectional strength of a pattern dowel is considerably less than that of a prefabricated metal dowel of the same size, for the metal dowels are drawn from a high fusing alloy, different than that used for the copings, and do not have the potential porosity and fracture of a cast dowel. www.indiandentalacademy.com
  87. 87. 87 3.PREFABRICATEDMETAL DOWELS The prefabricated metal dowels have a big advantage over the two previous systems because of the exact fit and high metallurgic strength in the cross sectional area; they require minimal enlargement of the canal space and strengthen the tooth rather than weaken it. The prefabricated metal dowels have matched sets of burs for exact fit of the preparation. The dowels are machined from high-fusing wrought metal that is specially alloyed for dowel usage. Most of these dowels have cement release grooves, which avoid the possible risk of incomplete seating or root fracture during cementation. www.indiandentalacademy.com
  88. 88. 88 4.THREADEDDOWELS Threaded dowels provide mechanical fixation in addition to cementation. The VK and Kurer systems offer excellent retention with the threading. 5.DOWEL SYSTEMS Schenker step pivot (European). V K and Kurer system www.indiandentalacademy.com
  89. 89. 89 CLASSIFICATION OF OVERDENTURES Heartwell: I . Noncoping II. Coping III.Attachments I. NONCOPING OVERDENTURES: Selected abutments are reduced to a coronal height of 2 to 3 mm and then contoured to a convex or dome shaped surface. Most teeth require endodontic therapy followed by amalgam or composite restoration. www.indiandentalacademy.com
  90. 90. 90 II.COPING OVERDENTURES: Coping Types A coping fitted to a prepared abutment is called a primary coping. The sleeve, or coping, that fits over this primary coping is referred to as a secondary coping. There are four basic types of primary copings: 1. Long copings (6-8 mm). 2. Medium copings (4-6mm). 3. Medium-short copings (2-4 mm). 4. Short copings (1-2 mm). www.indiandentalacademy.com
  91. 91. 91 1. Long Copings (6-8 millimeters for vital teeth): The long coping is an excellent restoration, applicable to many overlay techniques. It may be used simply to provide stability and retention under a telescopic overdenture. www.indiandentalacademy.com
  92. 92. 92 2. Medium Copings (4-6 millimeters for vital and non-vital teeth): Medium sized copings may be used with vital teeth where the pulp has receded or with non vital teeth having adequate bone support. Medium sized copings are not generally designed as individual copings for retention of the overlay prosthesis. They are generally connected with some type of bar attachment. Or, they may also be used with auxiliary plunger or pressure button attachments. They are conical with greater taper on all surfaces, particularly the facial surface when used with bar attachments. If used with a plunger button attachment, the surface engaged by the plunger is flattened. www.indiandentalacademy.com
  93. 93. 93 Abutment preparations for medium copings Medium copings www.indiandentalacademy.com
  94. 94. 94 With bar attachments To engage plunger Studs cantilevered www.indiandentalacademy.com
  95. 95. 95 3. Medium short copings (2-4 mm for nonvital teeth): Medium short copings are indicated for non-vital teeth; where a more favorable crown root ratio is desired than that possible with medium or long copings. This coping form (and preparation) is indicated when: it is difficult to obtain auxiliary retention of the coping on the abutment with a dowel or parallel pins (the proximal walls of the preparation should be very closely parallel for maximum frictional fit of the coping); numerous neighboring abutments are to be splinted, thus permitting better embrasure formation than possible with very short copings; used with bar attachments. www.indiandentalacademy.com
  96. 96. 96 4. Short Copings (1-2 millimeters for non-vital teeth): Short copings are fabricated to conform to the curvature of the alveolar ridge, with a very low profile. They are indicated for maximum favorable crown- root ratio. Such short copings are particularly suited to various types of stud attachments, but may also be used effectively with many forms of bar attachments. www.indiandentalacademy.com
  97. 97. 97 III. Overdenture with Attachments: The attachments essentially increase the crown- root ratio and then torque. Or apply horizontal or vertical dislodging forces to the root abutments. Here, low caries index, proper home care, periodontal health and inter ridge distance are absolutely necessary. www.indiandentalacademy.com
  98. 98. 98 ATTACHMENTS FOR OVERDENTURES The ultimate objective of the prosthetic service is to return the patient to as near a normal function as possible. The basic overdenture concept is to preserve the residual soft and hard tissues. Mechanical stabilization can be improved by incorporating the use of attachments and retentive devices with the basic principles of complete denture design. www.indiandentalacademy.com
  99. 99. 99 BASIC PROSTHETIC DESIGN It is important to realize that the causes of failure inherent in the complete denture prosthesis are not overcome by using attachment fixation. The use of attachments does not authorize the abandonment of basic principles. Failures of the hybrid prosthesis (overdenture with attachment fixation) occur not because of the attachments but because of improper attachment selection and failure of the dentist to develop maximum denture base extension, atmospheric seal, and, for mandibular bases, coverage of the retromolar pad. www.indiandentalacademy.com
  100. 100. 100 Availability of the proprioceptive elements in the attachment retained overdenture permits use of gnathologic procedures and, in some instances, anterior disclusion of the posterior teeth as well as the relevant instrumentation desired. Use of the attachment introduces another factor in basic prosthetic design, that is, the demand for an exact attachment prosthesis relationship. For each type of attachment the demand differs, depending on the availability or desirability of resiliency and the overall adaptation of the denture base over the soft and hard tissues of the denture bearing area. www.indiandentalacademy.com
  101. 101. 101 TOOTH PREPARATION Tooth preparation varies with the type of support to be provided. If there is sufficient tooth structure, that is, 3- to 8 mm of clinical crown for lateral stability of the overdenture, there are several methods of preparation. www.indiandentalacademy.com
  102. 102. 102 The coping is waxed to a minimal occlusal thickness of 1 mm with the exception of the bulk of the inlay seat. www.indiandentalacademy.com
  103. 103. 103 TELESCOPE CROWNS: The telescope crown is a prosthodontic retainer for a fixed or removable prosthesis and usually consists of the conical preparations with a like casting and a secondary telescope casting that is embedded in a prosthesis or is an abutment or crown itself. It is a system used to stabilize an overdenture where 4 mm or more of clinical crown is available. The advantage of the telescope crown or telescope preparation over the standard overdenture is the increased stabilization and retention of the denture while using remaining vital or nonvital teeth without dowels or screws. www.indiandentalacademy.com
  104. 104. 104 TELESCOPE OVERDENTURE: The telescoped overdenture is an excellent alternative to routine complete dentures. But what exactly is a telescoped or coping overdenture? As the name implies, a telescoped overdenture fits over natural teeth with that portion of the overdenture fitting like a sleeve. These supporting abutments may simply be endodontically treated teeth reduced slightly, shaped, smoothed, polished and left in this manner to support this denture; or, these roots or teeth may be restored with metal copings. The size of these primary copings, the copings on the teeth, may be medium or long. They may be designed only to provide support, or to provide support and retention. www.indiandentalacademy.com
  105. 105. 105 Advantages: 1. Conserve the alveolar ridge 2. Provide support and often retention 3. Retains some natural proprioception 4. Emotionally accept the overdenture 5. Easy modification possible 6. Auxiliary retention devices can be added 7. Easy to master 8. Less expensive than attachment fixation overdentures Disadvantages: 1. Retention is fixed, and not variable 2. Retention must be modified frequently 3. The overdenture is bulky and less esthetic 4. Expensive than a conventional complete denturewww.indiandentalacademy.com
  106. 106. 106 A Telescopic Overdenture Treatment Procedure: Following is a case of advanced periodontal disease and extensive breakdown of the natural dentition. The teeth were devitalized and restored with short and long copings to support an overdenture in the following manner: 1. Examination, diagnosis and treatment plan. 2. Study casts for fabrication of interim overdentures. 3. Prophylaxis, soft tissue curettage and home care instructions. www.indiandentalacademy.com
  107. 107. 107 Patient with extreme dental neglect Abutments are sectioned www.indiandentalacademy.com
  108. 108. 108 Preliminary endodontic therapy was carried out Abutment tooth are roughly prepared and hopeless roots sectioned www.indiandentalacademy.com
  109. 109. 109 Hopeless tooth and roots removed Periodontal surgeries carried out, interim dentures are very important at this stage worn for 3 months www.indiandentalacademy.com
  110. 110. 110 Tissues have healed and matured final preparation of tooth is done now After healing, the preparations were modified to receive medium or long copings. Short copings are to be placed on the two centrals. The other abutment teeth were prepared to receive long or medium copings. The overall preparation for the longer copings was tapering with a rounded occlusal or incisal. www.indiandentalacademy.com
  111. 111. 111 A chamfer, or small shoulder with a beveled marginal preparation, is prepared. This marginal preparation is determined primarily by the type of primary and secondary coping. If the secondary coping was a crown rather than a hollowed denture tooth, then the shoulder preparation must be more substantial. The final preparation of the teeth should result in a tapered cone shaped abutment rather than a rounded occlusal or incisal. This preparation should extend to the gingival sulcus as for a full crown preparation. Sufficient tooth structure was removed facially to make room for the coping and set up of the anterior teeth, thus ensuring a more esthetic result. The short anterior abutments were prepared for dowel post retention.www.indiandentalacademy.com
  112. 112. 112 Completed castings ready for cementation. Long copings for retention and stability and short copings for support and stability Copings cemented Now an impression was taken of the denture bearing mucosa and copings to produce a master cast for fabrication of the overdenture. www.indiandentalacademy.com
  113. 113. 113 Master casts articulated with accurate interocclusal records Coping undercuts are blocked out with plaster www.indiandentalacademy.com
  114. 114. 114 A metal framework with a horseshoe like major connector was fabricated on a refractory model Resin denture teeth were hollow ground to fit closely to the copings for maximum esthetics www.indiandentalacademy.com
  115. 115. 115 Completed overdenture Secondary copings www.indiandentalacademy.com
  116. 116. 116 A resin secondary coping of a telescoped overdenture does have some advantages over a metal secondary coping particularly where no auxiliary retentive means are used. It is easier to adjust the retention by adding autopolymerizing resin to the previously relieved secondary coping spaces and relining the coping spaces directly in the mouth. www.indiandentalacademy.com
  117. 117. 117 Relining and/or Rebasing As the alveolar ridges resorb, the overdenture will begin to rock and direct damaging lateral stresses to the abutment teeth. Now the prosthesis must be adjusted for a better fit by relining or rebasing. This is a simple procedure and performed similar to any complete denture relining or rebasing procedure: 1. Hollow out the secondary resin coping to provide adequate room for the impression material; 2. Paint an adhesive material on the denture base; 3. Load the tissue area of the overdenture with an elastic impression material; 4. Insert the overdenture in position and have the patient close gently into occlusion as you muscle trim; 5. Now the overdenture is relined or rebased similar to any complete denture technique and ready for use. www.indiandentalacademy.com
  118. 118. 118 ATTACHMENTS: Bar compared to stud fixation The splinting of two or more teeth with a bar produces stability similar to the rigid stud type attachment when the overdenture is in place. The question that arises immediately is: if the denture base is so well developed that the bar serves only as a fixation device, what is the difference in the result of splinting obtained in the stud prosthesis and in the bar prosthesis. Theoretically, there is no difference, but the stud type allows independent movement, and, if one tooth is especially weak, the strong tooth can serve as the fulcrum point for movement of the weaker tooth in the prosthesis.www.indiandentalacademy.com
  119. 119. 119 With bar units and joints, many times the bar splints in more than one plane. Instead of the prosthesis moving one tooth, all or none move under a functional load. With bar fixation, a stronger and a weaker tooth can be splinted with the result that the stronger tooth strengthens the weaker tooth and the weaker tooth weakens the stronger tooth. In making the overdenture; only the stud, the bar, and some of the accessory attachments are of interest. www.indiandentalacademy.com
  120. 120. 120 ATTACHMENTS CAN BE CLASSIFIED ACCORDING TOSHAPE, DESIGN, AND PRIMARY AREA OF USE AS FOLLOWS: (Mensor) Coronal 1. Intracoronal attachments 2. Extracoronal attachments Radicular 3. Telescope stud attachments (pressure buttons) 4. Bar attachments a. Joints b. Units www.indiandentalacademy.com
  121. 121. 121 Accessory 5. Auxiliary attachments a. Screw units b. Pawl connectors c. Bolts d. Stabilizers/balancers e. Interlocks f. Pins/screws g. Rests www.indiandentalacademy.com
  122. 122. 122 The various attachment systems have been organized in a compendium known as the EM attachment selector, which presents thirty points of information about each attachment (Mensor, 1973). This selector and the EM gauge (Matsuo, 1970) provide a simple color code method of choosing attachments from the mounted diagnostic casts. www.indiandentalacademy.com
  123. 123. 123 STUD(PRESSURE BUTTON) ATTACHMENTS: Most of the stud-type attachments can be considered to be "snap fasteners" and are the simplest in concept. They can be resilient or non resilient. www.indiandentalacademy.com
  124. 124. 124 RESILIENT STUDS Resilient attachment systems are selected to perform a compensatory service and to act as a safety valve for any overload situation. No two resilient attachment systems should oppose each other unless the attachments in the maxillary prosthesis are locked out of function, for the maxillary prosthesis receives additional support from the palatal coverage. This situation arises when two hybrid prostheses oppose each other or a mandibular appliance opposes the maxillary denture. www.indiandentalacademy.com
  125. 125. 125 When the mandibular appliance opposes a natural dentition, some provision should be made for movement so that maximal tissue contact of the denture base can be achieved under maximal load. In the well developed denture base with careful positioning of the attachments, the need for a resilient system becomes questionable. No attempt should be made at equilibrating or establishing permanent records or relining procedures without locking the resilient attachments out of function, because the base would move and produce incorrect markings of the interferences. www.indiandentalacademy.com
  126. 126. 126 The retained root with an attachment offers retention and positional or directional orientation for the appliance. When there is either inadequate technique or inability to develop a well fitting denture base, the resilient attachment gives some leeway to acceptance of the prosthesis by allowing more base contact and support during function. NONRESILIENT STUDS The nonresilient stud attachments are used when interocclusal space is limited. They should be used when the teeth are stable or when the dentist does not desire movement or potential movement of the overdenture.www.indiandentalacademy.com
  127. 127. 127 When to Use a Resilient Stud? A resilient attachment permits the tissue to compress slightly before any load is transmitted to the abutment. It is usually preferred: When there are only a few abutments. When abutments have minimal bone support. For tissue tooth supported prosthesis. When functioning opposite natural dentition. When functioning against a nonresilient appliance (do not use opposite another resilient appliance). When multi-directional (stress-broken) action is desirable. When there is a minimum denture base. www.indiandentalacademy.com
  128. 128. 128 When to use a non Resilient stud Attachment ? A non resilient attachment will not allow vertical movement (however it may permit rotational movement) When no vertical movement is indicated. When an all-tooth supported prosthesis is desired. When a tooth-tissue supported appliance is desired. With strong abutments having maximum bone support (one-half or more). When functioning against a resilient prosthesis When a large, well-fitting denture base is possible. When there is little interocclusal space Opposite a complete denture.www.indiandentalacademy.com
  129. 129. 129 Some Stud Attachments: 1. Dalla Bona 2. Intrafix 3. Ancrofix 4. Gerber 5. Gmur 6. Rotherman 7. Huser 8. Schubiger 9. Ceka www.indiandentalacademy.com
  130. 130. 130 The GerberAttachment The Gerber stud system is a versatile stud attachment used routinely. It consists of a male post soldered to the coping and a retentive female secured within the denture base of the overlay prostheses. The Gerber attachment is furnished in two different types - a resilient and non-resilient form. Resilient Gerber Non resilient Gerberwww.indiandentalacademy.com
  131. 131. 131 The male post consists of two parts - a threaded base, which is soldered to the diaphragm of a coping, and a removable sleeve with a retentive undercut The resilient female consists of a housing, coiled spring, C- spring, a retention sleeve and lock screw. The non-resilient female has a female housing, C spring and a screw cap and no copper shim and coil spring. www.indiandentalacademy.com
  132. 132. 132 Convenient tools are also used in the fabrication - female screwdriver, male screwdriver, paralleling mandrel, heating bar, and a soldering cornal www.indiandentalacademy.com
  133. 133. 133 Step-by-Step Technique: 1. All treatments must start with a thorough oral examination. This examination should include patient history, visual examination, radiographs and periodontal probe evaluation. Accurate study casts mounted on an appropriate articulator are also helpful. 2. A thorough oral prophylaxis and home care instructions are completed before any other treatment is performed. 3. Fabricate an interim overdenture on the diagnostic casts for insertion after reduction of the clinical crowns, endodontics, extractions and periodontal surgery. www.indiandentalacademy.com
  134. 134. 134 4. All the teeth are reduced to one to two mm above the gingiva 5. Endodontics is performed 6. Partial preparation of the teeth 7. Extraction of hopeless dentition 8. Hollow out recesses in the interim overdenture 9. Now that the teeth have been initially reduced, the hopeless dentition removed, and the interim overdenture ready for insertion, periodontal therapy can be completed in a relaxed manner with relative patient comfort. www.indiandentalacademy.com
  135. 135. 135 10.Insert the interim overdenture with a soft relining material 11.After several weeks of healing, complete endodontics (if not completed). 12.After tissue healing and maturation (2-3 months) complete abutment preparations for short copings with post retention. www.indiandentalacademy.com
  136. 136. 136 13.Master cast with removable dies 14.Copings waxed on individual dies shaped to conform to the alveolar ridges. Resin dowels were used as dowel patterns www.indiandentalacademy.com
  137. 137. 137 15.Position the finished castings on the cast (lock them together with Duralay); invest and solder them to form a splinted substructure 16.Preliminary intraocclusal relation records for a trial set-up of denture teeth. The anterior teeth are oriented with a plaster core. This helps to accurately position the male attachment on the copings www.indiandentalacademy.com
  138. 138. 138 17.Position the male attachment on the coping. Consider the following factors when determining the position of the male posts: - Is there sufficient vertical space? - Place the posts over abutments with the most bone support. - Position the males slightly lingual. This provides more room for the anterior denture teeth. - Utilize abutments in different planes for maximum retention, stability and support . - The attachments must be parallel to each other and to the path of insertion of the overdenture www.indiandentalacademy.com
  139. 139. 139 18.Lock the cast on the surveying table. Loosen the male sleeves and Place in the paralleling mandrel. Find the most advantageous position for the posts. Tilt the surveying table so that the studs will be aligned to the path of insertion of the prosthesis. 19.Sticky-wax the male base to the coping www.indiandentalacademy.com
  140. 140. 140 20. Male sleeve is being removed 21. Male stud sticky waxed to the coping with sleeve removed www.indiandentalacademy.com
  141. 141. 141 22.Screw the soldering cornal onto the threaded base. It acts as an extension arm for the screw to aid in soldering 23.Cover half of the soldering cornal and coping with soldering investment. www.indiandentalacademy.com
  142. 142. 142 24. Finished copings with attachments assembled and soldered, positioned on the abutments 25.Take an accurate muscle trimmed master impression "pulling" the coping substructure, on the abutments, to form the master cast for the overdenture fabrication www.indiandentalacademy.com
  143. 143. 143 26. 3-4 thickness of x - ray foils are adapted to all copings for spacing. 27. Block out all undercuts around the foil spacer and copings with plaster www.indiandentalacademy.com
  144. 144. 144 28.Place a small amount of Vaseline inside each female then snap it (with its copper shim) onto the male 29.Paint a thick mix of auto- polymerizing resin at the male-female joint. This will prevent processed denture acrylic resin from being forced into the attachment during denture packing procedures www.indiandentalacademy.com
  145. 145. 145 30.Design the framework with a major connector for support and a minor connector for the acrylic denture base. Fabricate and finish 31.Take accurate occlusal records and mount the casts on an appropriate articulator for the denture setup and denture is fabricated www.indiandentalacademy.com
  146. 146. 146 32.Females locked inside. All excess plaster and resin is removed. Use the female screwdriver to disassemble the female, remove the copper shim and reassemble. This activates the attachment making it resilient. 32.The overdenture is ready for insertion www.indiandentalacademy.com
  147. 147. 147 Cement the copings onto the roots and insert the overdenture www.indiandentalacademy.com
  148. 148. 148 Non-Resilient Gerber The non-resilient Gerber attachment technique is similar to that described above but with one exception. As it is non-resilient, the overdenture and female rest on the tissues, copings and male posts in a passive position; no spacing is necessary. Therefore, do not place spacers over the copings. (Of course, the non-resilient Gerber has no copper shim spacer.) www.indiandentalacademy.com
  149. 149. 149 Maintenance Consideration Relining or Rebasing Alveolar resorption will eventually cause the denture to rock about the abutments. This rocking will increase the rate of resorption; abutment bone support will be continually lost. Such destructive action may even cause dislodgement of the copings, breakage of attachments, or even the splitting of the abutment. The appliances should be relined or rebased to eliminate these stressful forces. www.indiandentalacademy.com
  150. 150. 150 Remove the internal parts of the female with the female screwdriver. Carefully set aside all internal parts to be reassembled later. Screw the relining heating tool into the female. Heat the end of the bar in a Bunsen burner flame. The heat transfer will soften the acrylic around the female, making it easy to remove Procedure for relining www.indiandentalacademy.com
  151. 151. 151 Grind out several millimeters of the acrylic resin within the female recess. Place the female attachments (with their copper shims in place) over the posts in the mouth. Place an adhesive on the tissue side of the overdenture, fill the prosthesis with an elastic impression material and take the impression using a routine complete denture relining impression technique. Have the patient close into occlusion while the impression material sets.www.indiandentalacademy.com
  152. 152. 152 Male relining jig Insert the special male relining jigs (transfer males) into the females until a definite snap is felt www.indiandentalacademy.com
  153. 153. 153 The set cast, with the overdenture, is articulated to a special relining jig. The relining or rebasing procedure is similar to a conventional denture relining or rebasing technique. Separate the articulator and remove the cast from the overdenture impression. The cast has the transfer males in the same location as in the mouth The cast and attachment management is handled like the initial fabrication technique: the spacers are placed over the stone copings; females (with their copper shims) are placed on the males; all undercuts are blocked out with plaster; the denture teeth are repositioned on the cast via the relining jig, and the overdenture is fabricated by any conventional denture procedurewww.indiandentalacademy.com
  154. 154. 154 Advantages of the Gerber attachment 1. It provides adequate retention, stability and support. 2. Its retention is light and easily adjustable with springs adjustable and readily replaced. 3. All of its post sleeves are interchangeable and replaceable, with the exception of the male screw base. 4. It can be used in conjunction with bars. 5. It can be processed directly into the overdenture or positioned in the mouth with autopolymerizing resin. www.indiandentalacademy.com
  155. 155. 155 Disadvantages of Gerber attachment 1. It is a complex attachment and maintenance problems are relatively common. The male sleeve may become loose. The internal parts of the female may dislodge when the retaining screw unthreads. 2. Its large vertical dimension makes it impractical for minimal interocclusal space. 3. It requires an assortment of tools for fabrication and maintenance. 4. The attachments must be parallel. 5. The Gerber permits very little rotational action, so torquing of abutment teeth will occur with alveolar resorption. www.indiandentalacademy.com
  156. 156. 156 Dalla Bona Attachment The Dalla Bona is a simple stud attachment making an excellent overdenture attachment available in a resilient or nonresilient series. It is useful when there is minimal vertical space and where rotation, resilience and retention are desired. It consists of a single piece male stud soldered to the coping and a single unit female processed within the denture. It is available in two types: 1.Cylindrical 2.Spherical One form even has an internal coiled spring much like the resilient Gerber. This spring helps control vertical movement. The Dalla Bona series is an excellent attachment. www.indiandentalacademy.com
  157. 157. 157 Dalla bona attachments on two cuspids makes it excellent overdenture arrangement Spherical Bona with undercut for retention www.indiandentalacademy.com
  158. 158. 158 Male is a solid stud, female is a single component with retentive lamellae. A clear Teflon ring covers the female lamellae Restored roots with copings and spherical bonas www.indiandentalacademy.com
  159. 159. 159 Cylindrical Dalla Bona The cylindrical male post has parallel walls without an undercut. The female lamella fits snugly over the male posts, providing frictional retention. A PVC ring fits around the female lamellae. This aids in fabrication, and permits the lamellae to flex. The cylindrical Dalla Bona must be parallel; therefore, the male posts must be assembled using a paralleling mandrel and surveyor. www.indiandentalacademy.com
  160. 160. 160 Spherical Dalla Bona The spherical Dalla Bona is similar to the cylindrical, but the male post is spherical. This sphere provides a retentive undercut which is engaged by the retentive lamellae of the female. If a spacer is used during fabrication, this attachment will be resilient; without the spacer, it will be nonresilient. www.indiandentalacademy.com
  161. 161. 161 Advantages 1. Their overall length varies between 3.3 millimeters (cylindrical), to 3.7 millimeters (spherical), so it is suitable for short interocclusal spaces. 2. It provides firm, definite retention. 3. It can be processed into the overdenture in the laboratory or mounted in the mouth using autopolymerizing resin. 4. It is less expensive than the Gerber. 5. Parallelism of the spherical Bona is less critical than that of the cylindrical Bona. www.indiandentalacademy.com
  162. 162. 162 Disadvantages 1. The retentive action of the female is very stiff and difficult to adjust. 2. The collar that retains the female housing in the prosthesis is too small. Therefore the female may become loose with normal adjustments and use. 3. The males must be parallel, particularly in the cylindrical form. 4. There may be some torquing and tipping of the abutment. www.indiandentalacademy.com
  163. 163. 163 Spherical Dalla Bona Treatment Diagnosis, treatment and management using the Dalla Bona are very similar to that described for the Gerber. Step by step procedure 1. The various clinical steps depend on the existing conditions. They would normally include examination, diagnosis, home care, initial preparation, endodontics, extractions, periodontics, interim overdentures, final preparations and casts with removable dies for coping fabrication. www.indiandentalacademy.com
  164. 164. 164 Casts with the removable dies are fitted with the resin dowel pattern coping pattern is waxed www.indiandentalacademy.com
  165. 165. 165 To improve the soldering procedure, cut a ditch in the diaphragm of the coping. This ditch aids the flow of solder under the stud base With the cast on a surveying table, use a paralleling mandrel to position the male studs parallel to each other. Located slightly lingual. Now sticky wax them into position. www.indiandentalacademy.com
  166. 166. 166 Add a short strip of round wax to one side of the waxed base. This will produce flame vent holes within the investment material. This also aids the soldering procedure Preheat in an oven to 1400 degrees F. Flame solder the male to the coping by adding solder in the prepared ditch. The copings with their soldered attachments are now polished and ready for assembly. www.indiandentalacademy.com
  167. 167. 167 The coping substructure is withdrawn from the abutments with an accurate muscle trimmed impression to become integral part of the master cast The female snapped on to the stud. The Teflon ring is positioned firmly on the base www.indiandentalacademy.com
  168. 168. 168 Block out all coping undercuts with plaster The casts are articulated on an appropriate articulator with accurate occlusal records for set up of the denture teeth. The overdenture, with an all- metal base is processed and finished for insertion with the female retained inside the denture base www.indiandentalacademy.com
  169. 169. 169 The Rotherman Attachment The Rotherman is another excellent stud attachment. The Rotherman consists of a solid stud (that is soldered to the coping) and a clasp like female (that is mounted in the overdenture. Like many stud attachments, it is available in both resilient and nonresilient designs. The resilient form has a taller male and is supplied with special spacers. The Rotherman is particularly applicable where interocclusal space is limited, as the nonresilient design has a vertical dimension of just 1.1 millimeter and the resilient just 1.7 millimeter. www.indiandentalacademy.com
  170. 170. 170 The Rotherman anchorage has a short solid stud( non resilient right, resilient left) and a double armed clasp. The clasp has bar for retention within the denture base Non resilient left and resilient right with aluminum spacer www.indiandentalacademy.com
  171. 171. 171 The male features a definite undercut on just one side of the cylinder. A scribe line on the occlusal indicates the position of maximum undercut. The male must be soldered to the coping so that this line (and the undercut below it) is positioned facially. This way, the female's clasp arms will reach around from lingual to engage the undercut and the bar like retentive lug will fall in the lingual portion of the denture. There it will not interfere with the tooth setup and will be locked in thicker resin. The Rotherman is the easiest of all attachments to solder, for it comes with solder built into the center of the male. The technician need only position the male on the coping and then hold it in a flame until the solder flows.www.indiandentalacademy.com
  172. 172. 172 Ancrofix Attachment The Ancrofix is similar to the spherical Dalla Bona with a rounded male post providing the undercut for retention. Of course, the female is processed within the overdenture. This attachment consists of a male base which is soldered to the coping diaphragm, a removable sleeve knob that provides the undercut; the female has adjustable lamellae that engage the male undercut for retention. A Teflon ring covers the female lamellae similar to the Dalla Bona. This attachment is 3.2 millimeters in height and can be used in most instances a rotational action is desirable. It can be made resilient by removing the small knob located on top of the male stud and by spacing the copings.www.indiandentalacademy.com
  173. 173. 173 Ancrofix stud Male stud and female with Teflon sleeve www.indiandentalacademy.com
  174. 174. 174 BAR ATTACHMENTS As the name suggests, bar attachments consist of a metal bar that splints two or more abutments and a companion mechanism processed within the tissue area of the overdenture. This mechanism snaps on the bar to retain the prosthesis. Bar attachments are available commercially in a wide variety of forms or they can easily be "custom" fabricated. www.indiandentalacademy.com
  175. 175. 175 Types of BarAttachments Bar units Bar joints www.indiandentalacademy.com
  176. 176. 176 The Bar Unit This bar has parallel walls providing rigid fixation with frictional retention. It can be used for retention with long, medium or short copings, but only when the appliance is to be an all tooth supported appliance (i.e. where no stressbroken or rotational action is indicated). It is never used when a bar joint is indicated (when rotational or vertical action is necessary); however, a bar joint can be used whenever a bar unit is indicated. www.indiandentalacademy.com
  177. 177. 177 The Bar Joint The action of this attachment provides rotational or vertical movement. In other words, it is a stress broken attachment. It has a rounded or semi rounded contour so the retention clip and prosthesis can rotate slightly during mastication. www.indiandentalacademy.com
  178. 178. 178 The Dolder Bar An ideal bar attachment is the Dolder bar. It is well designed for splinting two or more abutments to provide support, stability and retention for the overdenture. This bar attachment is manufactured in two forms a bar joint and a bar unit. It is also available in two different diameters and lengths. www.indiandentalacademy.com
  179. 179. 179 Dolder bar joint The pear shaped bar joint is designed to provide vertical and rotational action so it is indicated where a stress-broken, resilient attachment is desired. It can also be used as a bar unit for an all tooth supported prosthesis by fabricating the overdenture without planned vertical movement. Dolder bar unit The bar unit is in the form of an inverted U with parallel walls. It does not permit rotational or vertical movement; therefore it only provides retention and support, but maximizes the masticatory load on the abutments. www.indiandentalacademy.com
  180. 180. 180 Typical Dolder bar Treatment: • Endodontics, extractions and periodontal surgery were completed prior to starting the operative process. Tooth preparations were started only after healing. Reduce the endodontically treated cuspids to one to two millimeters above the gingiva. www.indiandentalacademy.com
  181. 181. 181 Diamond bur is used to prepare the abutments with a bevel or chamfer margin. X indentation is made. The copings can be retained with posts, parallel or non- parallel pins, or a combination of both. As the two cuspids will be splinted with the bar joint, the posts (used in this case) must be parallel to each other. The para-post system was used to prepare these parallel "sized" holes to receive the impression posts. Enlarge the canal opening with a number six or eight bur to one half of the bur head depth. This adds strength to the dowel casting union here. www.indiandentalacademy.com
  182. 182. 182 Fabricate a customized impression tray on the study cast. Prepare holes in the tray over the root preparations. The impression posts will pass through these holes. Take a muscle trimmed impression of the teeth and soft tissue areas. The previously positioned impression posts are withdrawn with the impression www.indiandentalacademy.com
  183. 183. 183 Plastic dowels used as dowel patterns Short coping patterns are waxed to conform to curvature of the alveolar ridge www.indiandentalacademy.com
  184. 184. 184 The copings are finished, but are left with a short section of the sprue on each casting which will be removed later. These retained sprue posts aid in the assembly of the bar to the copings for soldering Set up the denture teeth and check with the patient for occlusal harmony, vertical dimension and esthetics www.indiandentalacademy.com
  185. 185. 185 Cut the bar to fit between the copings. The bar should be positioned slightly lingual Connect the bar to the copings (the short sprue stubs help here) with Duralay, or sticky wax. Invest and solder to the copings. www.indiandentalacademy.com
  186. 186. 186 Retentive shell is cut and fit over the bar Shell is modified for better retention Method of modification www.indiandentalacademy.com
  187. 187. 187 The metal spacer is positioned over the bar and the retentive shell is snapped on the bar securing the spacer. Space must also be provided over the copings. www.indiandentalacademy.com
  188. 188. 188 Block out all undercuts around the copings with plaster and cover the flanges of the retentive shell Consequence of excessive block out www.indiandentalacademy.com
  189. 189. 189 With a small brush, sparingly paint a semidry mix of auto polymerizing acrylic resin (such as Duralay) to cover the end of the spacer and shell Framework is constructed and secured on the cast www.indiandentalacademy.com
  190. 190. 190 Use the stone index to reposition the anterior teeth and complete the denture set-up The denture is waxed, festooned, flasked, processed and finished. The coping bar assembly is removed but the retentive shell is retained within the tissue side of the denture www.indiandentalacademy.com
  191. 191. 191 Cement the Dolder bar/coping assembly into position. The overlay denture is inserted for use. www.indiandentalacademy.com
  192. 192. 192 Overdenture Function Let us now consider the function of this overdenture. Freedom for vertical movement, provided by the auxiliary wire spacer and lead foil covering the copings during fabrication, allows approximately 0.5 to 1.0 millimeter of space for movement during function www.indiandentalacademy.com
  193. 193. 193 At rest, the overdenture sits passively only on the alveolar tissues. A space is present between the bar- coping assembly and the shell tissue side of the overdenture. There is maximum retention now since the clip engages the bar undercut During mastication, the denture moves vertically. Now it is supported by both the alveolar tissues and the root supported coping bar substructure. www.indiandentalacademy.com
  194. 194. 194 Adjusting Retention: Retention of the overdenture is easily increased or decreased by adjusting the flanges of the shell to provide desirable retention. Relining/Rebasing Technique As the alveolar ridge resorbs, the overdenture settles and rocks on the Dolder bar assembly. These excessive masticatory loads direct damaging torquing stresses to the abutments. When this occurs, the following rebasing procedure should be followed. www.indiandentalacademy.com
  195. 195. 195 1. With a small round bur, carefully remove the acrylic around the shell, and remove the shell. It will be used later. 2. Remove additional acrylic above the area of the copings and bar using a straight handpiece with a number eight bur. This additional space will accommodate the impression material. 3. Dry the denture and paint the tissue areas with an impression adhesive. 4. Using the elastic impression material of your choice, take an impression of the tissue bearing areas, copings and Dolder bar. The patient should close gently into occlusion, as you muscle trim the impression material. When a large space is present under the bar or between the copings, it should be blocked out with soft wax or cement prior to taking the impression. Otherwise, tearing away of the impression material from these voids, when the impression is removed, will distort and destroy the accuracy of fit when the prosthesis is rebased. www.indiandentalacademy.com
  196. 196. 196 5. The impression is poured with model stone. 6. The cast with the overdenture attached is mounted in a relining jig. The teeth are indexed in the opposing member and the jig is opened after the plaster has set. www.indiandentalacademy.com
  197. 197. 197 7.The overdenture is removed from the cast leaving a reproduction of the soft tissue, the copings and Dolder bar. 8. The denture teeth are removed from the overdenture and are positioned in their appropriate slot in the plaster index. www.indiandentalacademy.com
  198. 198. 198 9. The cast is now treated as if you are fabricating a new overdenture i. e, • Place three to four layers of X-ray foil over each coping as a spacer. • Place the metal spacer over the mold of the bar. • Snap the retentive shell into position over the spacer and plaster bar. • Using plaster, block out the retentive flanges of the shell and all undercuts. • Block the ends of the shell and spacer with resin. • Reposition the cast on the relining jig; wax the teeth into position; wax the denture base; festoon, flask, pack, cure and finish the overdenture as in any complete denture technique. • The rebased overdenture is now ready for insertion.www.indiandentalacademy.com
  199. 199. 199 The Dolder Bar Unit The Dolder bar unit is an excellent attachment when an all tooth supported, non rotational acting overdenture is desired. This bar design may be indicated if there are numerous abutments - especially if they are located in three planes; i.e. posterior and anterior abutments. www.indiandentalacademy.com
  200. 200. 200 The Hader Bar System The Hader system is an excellent bar attachment. Similar to the customized bar, the Hader system consists of a plastic bar pattern with gingival extension and small plastic clips that are processed into the overdenture. This system has some advantages over others; the plastic bar pattern's gingival extension can be trimmed to conform to the ridge. In addition, worn clips can be easily replaced at chair side using a special seating tool. www.indiandentalacademy.com
  201. 201. 201 Components of the Hader system are (from left to right). • Plastic bar pattern (1.8 mm diameter, vertical height 5.7 mm). • Plastic clips (5 mm long, 3 mm thick, 4 mm high). • Modeling riders used in processing to create a slot for the clips. • Clip seating tool. www.indiandentalacademy.com
  202. 202. 202 Hader Bar Technique • Take an impression of the prepared abutments, pour a cast and trim the dies as you would any bar retained overdenture. • Wax the coping pattern on the dies. • Cut the bar pattern to fit between the coping patterns. • Heat the bar pattern and adapt it to the ridge curvature. • Trim the gingival portion of the bar pattern to fit the alveolar ridge. • Wax the plastic pattern directly to the coping patterns for a single casting, or for greater accuracy, cast separately and solder to the copings www.indiandentalacademy.com
  203. 203. 203 7.The completed substructure pattern is sprued, invested, cast and finished. 8.Seat the substructure on the cast for completion of the overdenture www.indiandentalacademy.com
  204. 204. 204 9. Position modeling riders on the bar where clips will attach. These riders are removed after the prosthesis is fabricated, leaving a preformed seat to receive the plastic clips for retention. 10.Using plaster, block out all undercuts around copings and below the round portion of the bar www.indiandentalacademy.com
  205. 205. 205 11.When the overdenture is finished, remove the modeling riders with pliers or a sharp instrument 12. Use the special seating tool to insert the plastic clip into the slots formed by the modeling rider www.indiandentalacademy.com
  206. 206. 206 13.The denture is now ready for use Metal clips for retention If a metal rider is preferred, it should be incorporated into the prosthesis when it is initially fabricated. Instead of using the modeling rider, substitute the metal riderwww.indiandentalacademy.com
  207. 207. 207 Advantages of the Hader System 1. The plastic bar pattern is easily adapted to differences in the surface of the gingival ridge and gingival curvature. 2. The plastic bar pattern simplifies the laboratory technique by eliminating a soldering step. 3. Plastic riders give adequate retention and are easily replaced. 4. Its rotational joint action relieves stresses from the abutment teeth. The main disadvantage of this system is its plastic rider which cannot be altered for additional retention. However, the adjustable metal riders can be used to eliminate this problem. In addition, there is no provision for developing vertical function with the overdenture. Commercial retentive clips can be used with these customized bars.www.indiandentalacademy.com
  208. 208. 208 AUXILLARY ATTACHMENTS In addition to bars and studs, other attachment systems are applicable for overdenture prostheses. These auxiliary attachments may be in the form of screws or spring loaded plunger attachments. www.indiandentalacademy.com
  209. 209. 209 SCREWS: Schubiger Screw Attachment An excellent screw attachment often used in overdenture technique is the Schubiger. This attachment is a very versatile screw-type system, used with Gerber and bar combinations. www.indiandentalacademy.com
  210. 210. 210 Plunger-Type Attachments Auxiliary retention for an overlay prosthesis is often desirable and it may be added to various coping or bar systems. Plunger type units such as the Ipsoclip, Presso-matic and IC attachments can add additional retention www.indiandentalacademy.com
  211. 211. 211 Review of literature Paul A. Miller ( 1958) gave special emphasis on preservation of tissues with support of artificial teeth. The use of teeth as support for dentures is aimed at reducing the load on the osseous portions of the denture bearing area and minimize the process of resorption. www.indiandentalacademy.com
  212. 212. 212 Dolder E. J. in 1961 advocated the bar joint denture. The denture is adapted primarily to the situation with which only a few teeth remain. The basic construction procedures consist of (1) Shortening and capping the residual teeth to render the crown: root length ratio more favorable and (2) Splinting the abutments with a straight bar affixed to the cemented copings which serves, at the same time, as the bearing shaft for the complete denture. www.indiandentalacademy.com
  213. 213. 213 Robert J. Crum and R. J. Loiselle (1972) in his review of literature reveal that discrete sensitivity that exists in the separate components of masticatory system. It also demonstrates the necessity for total integration of each component of the masticatory system and signals the importance of preserving the natural teeth. www.indiandentalacademy.com
  214. 214. 214 Merrill C. Mensor (1973) advocated the use of E M attachment selector which consists of 8.5 by 11 inch color coded selector cards. It is compendium of attachments and connecting units available through out the world and it contains 30 points of information for each of more than 105 different attachment systems, this is a total of over 3000 points of information. Each of the cards numbered to correspond with 5 attachment classifications. www.indiandentalacademy.com
  215. 215. 215 Joseph T. Quinlivan (1974) said that retention is a problem for overlay dentures over simple copings when only two teeth remain. This is particularly a problem when treating a mandibular arch, which has a more limited basal seat area. He advocated RCT of the abutment teeth; pulp space to be enlarged with a Gates Glidden drill and finally with a safe sided para post drill. Then he advocated used ball and socket type of attachment for overdenture on the teeth reduced I mm above the gingiva. www.indiandentalacademy.com
  216. 216. 216 Wayne R. frantz (1975) described the construction of tooth supported dentures where the natural tooth was utilized and the acrylic resin for denture base processed directly to the prepared cast. He said that abutment teeth with their coping may result in 3-5 mm above the gingiva which causes undue stress and torque on the teeth. He advocated natural teeth to be reduced 1-2 mm above gingiva fill the pulp chamber with amalgam and give a very high polish and construct the denture. www.indiandentalacademy.com
  217. 217. 217 A. B. Warren and A. A. caputo (1975) conducted a study to determine and compare the transfer of forces to the alveolar bone for five different abutment designs for the tooth supported dentures and concluded that there was a direct relationship between the stability and retention that each design provided and the amount of stress and torque transferred to the supporting structures. Attachments that used parallelism or undercuts for retention tend to produce the most severe stress conditions in the supporting alveolus. www.indiandentalacademy.com
  218. 218. 218 H H Thayer and A A Caputo (1977) provided the following guidelines in the selection of specific designs for overdenture abutments: 1.The Dolder bar, which exhibits more cross-arch involvement than the Zest anchor, will share the occlusal load across the arch, between the abutments and the supporting structures. 2.The posterior edentulous regions will receive some physiologic stimulation with the Dolder bar, for it shares more stress here than the Zest anchor. www.indiandentalacademy.com
  219. 219. 219 3. The forces on the Dolder bar produce stress directed more apically than that from the Zest anchor. Since this force is better tolerated, use of the Dolder bar may be indicated for a short- rooted tooth with less supporting bone. 4. The greater stress concentrated around the abutment teeth by the Zest anchor makes use of this design in a tooth that is periodontally sound and has a long root structure well imbedded in supporting bone seem logical. www.indiandentalacademy.com
  220. 220. 220 Merrill C. Mensor (1978) said that when selecting an attachment it is essential to consider the skill of the dentist – laboratory teem as well as dexterity of the patient and to use the easier system that will still improve stabilization. He advocated the use of E M gauge and E M attachment selector to reduce confusion in selection attachments. www.indiandentalacademy.com
  221. 221. 221 Robert J. Crum and George E. Rooney (1978) conducted a 5 year clinical study to determine the amount of bone loss in the anterior part of the maxillae and the mandible in two groups of patients: one group with complete maxillary dentures and mandibular overdentures and other group with complete maxillary and mandibular dentures. The result show that group –I demonstrated less alveolar bone reduction than group –II. www.indiandentalacademy.com
  222. 222. 222 H. H. Thayer and A. A. Caputo (1979) concluded that a) The more retentive tissue bar and extra coronal attachments produces higher stress concentrations b) The Hader bar produced less torquing forces c) The Ancrofix appeared to share the forces of occlusion between the abutments and the posterior edentulous regions. www.indiandentalacademy.com
  223. 223. 223 Gary D.Derkson and Michael Macentee ( 1982) conducted a study to observe the therapeutic effect of 0.4% stannous fluoride gel on the periodontium and the tooth structure of overdenture abutments and they found that 0.4% stannous fluoride gel is an effective agent in reducing the progress of gingivitis around overdenture abutments. www.indiandentalacademy.com
  224. 224. 224 Conclusion: To conclude it would not be a repetition to say that overdenture is a preventive dentistry concept which has been brought into Prosthodontics. The alveolar bone and its overlying mucosa was never intended to receive the full force of the complete denture. Even though the technique resembles those of complete dentures, there are important differences. The prognosis of the restoration is likely to be influenced by numerous factors like: www.indiandentalacademy.com
  225. 225. 225 1) Selection of patient 2) Treatment planning 3) Preparation of the mouth 4) Execution of the prosthodontic work 5) Maintenance Finally it is reasonable to conclude that retention of the part of the natural dentition affords the overdenture patient a gain in neuromuscular performance thereby having an edge over his edentulous counterpart. www.indiandentalacademy.com
  226. 226. 226 References 1. Brewer AA, Morrow RM: Overdentures, ed 2. St Louis, CV Mosby, 1980. 2. Crum RJ, Rooney GE Jr: Alveolar bone loss in overdentures: A 5-year study. J Prosthet Dent 1978;40:610-613. 3. DerksonGD, MacEntee MM: Effect of 0.4% stannous fluoride gel on the gingival health of overdenture abutments. J Prosthet Dent 1982; 48:23-26. 4. Ettinger RL, Taylor TD, Scandrett FR: Treat-ment needs of overdenture patients in a longitu-dinal study: Five-year results. J Prosthet Dent 1984;52:532-537. 5. Mensor MC Jr: Attachment fixation of the overdenture: Part II. J Prosthet Dent 1978;39:16-20. www.indiandentalacademy.com
  227. 227. 227 6. Quinlivan JT: An attachment for overlay dentures. J Prosthet Dent 1974;32:256-261. 7. Thayer HH, Caputo AA: Occlusal force transmis-sion by overdenture attachments. J Prosthet Dent 1979;41:266- 271. 8. Thayer HH, Caputo AA: Effects of overdentures upon the remaining oral structures. J Prosthet Dent 1977;37:374- 381. 9. Winkler .S . Essentials of complete denture Prosthodontics, second edition,2000, 384-402. 10.Paul A. Millar: complete denture supported by natural teeth. J Prosthet Dent 1958;8:924. 11.Dolder E. J: The bar joint mandibular dentures. J Prosthet Dent 1961;11:689. www.indiandentalacademy.com
  228. 228. 228 12.Wayne R Frantz: The use of natural teeth in overdentures. J Prosthet Dent 1975;34:135-140. 13.A B Warren and Caputo: Load transfer to alveolar bone as influenced by abutment designs for tooth supported dentures. J Prosthet Dent 1975;33:137. www.indiandentalacademy.com
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