Tooth-supported overdentures guide

Tooth
supported
overdentures
DR. SWAPNANEEL PRADHAN

Introduction
Definitions:
“Any removable dental prosthesis that covers or rests on one or
more remaining natural teeth, the roots of natural teeth ,and/or dental
implants; a dental prosthesis that covers and is partially supported by natural
teeth, natural tooth roots, and/or dental implants.”
– GPT – 9
“A removable prosthesis that covers the entire occlusal surface of a
root or implant.”
– Harold W. Preiskel

History
• 1856 – Ledger had described a prosthesis resembling over dentures.
• 1861 – ‘Plates covering fangs’ by Atkinson.
• 1888 – Evans described a method of using roots to retain
restorations.
• 1896 – Described telescope like coping.
• 1909 – ‘Focal sepsis theory’ by William Hunter.
However there was little enthusiasm of Hunter’s theory in
Europe and overdentures and similar prostheses were continued to be
made.

Advantages of preserving teeth or roots
1. Psychological benefits to the patient
2. Effects upon the edentulous ridge
3. Tactile discrimination
4. Improved stability and retention of the denture
Overdentures Made Easy by Harold W. Preiskel

1. Psychological factors
• Loss of remaining teeth can be a disturbing and emotional experience
for many.
• Loss of teeth is associated with aging, and this can be depressing
factor for many.
In the past, the stigma and taboo associated with losing teeth
was so significant that people were interested to retain even rotten
roots with purulent exudates around them.

2. Effects upon the edentulous ridge
• In 1969, Tallgren showed that over a period of 7 years, the reduction in
anterior ridge of the mandible was 4 times more than that of maxillary
edentulous ridge.
• In 1972, Atwood and Cow also corroborated with this finding of Tallgren.
• In 1978, Crum and Rooney reported a 4-year study in which they claimed
that the retention of mandibular canines for overdentures helped to
preserve the remaining edentulous ridge.
• Their study showed that, the anterior ridge resorption of mandible was on
average only 0.6mm in patients with overdentures where as the ridge loss
was on average 5mm in patients wearing complete denture.

• Effective mastication requires tactile discrimination.
• Loss of teeth leads to loss of mechano-recepters associated to the
PDL.
• However, the feed back mechanism appears to extend beyond the
PDL (as anaesthetizing the teeth have little effect on the
discriminatory ability.
• In addition to that, patients with implant supported restorations
demonstrate very effective masticatory efficiency even though there
is absence od PDL.

• While receptors in the mucosa, proprioception in the muscles and
TMJ may all influence discrimination, PDL appear to play a significant
role.
• Mericske-Stern demonstrated that when a thin test foil was placed
between the artificial teeth, the ability to perceive it was better in
root supported overdentures as compared to implant supported
overdentures.
However, there is no evidence that better tactile sense
improves chewing capacity, chewing comfort or maximum biting
force.

4. Improved stability and retention
• Vertical walls of the remaining roots provide extra stability to the
denture. (Greater the vertical space occupied by the root preparation,
greater the stability.)
• Additional retention is produced by parallel vertical wals of the
copings or by attachments.

Advantages of overdentures
1. Greatly Enhanced Stability: Anteroposterior and lateral slipping and sliding are eliminated, as is
the associated ridge trauma.
2. Positive Retention: This is facilitated by the greatly reduced crown root ratio which lodges into
the slot in the tissue surface of denture base.
3. Proprioception: This unique sensitivity seems to reside to a large extent in the tissues of
periodontium and provides an awareness of jaw space relationship and protection from accidental
injuries due to over closure of the jaws.
4. Psychological Benefits: As long as the roots are preserved, the patient is spared of the
emotional trauma associated with the total loss of their dentition.
5. Post Extraction Comfort: The common denture sore spots that often follow total extraction are
greatly diminished because the overdenture is resting on tooth structure during this post operative
period.
6. Positive Support and Comfort: The patient is much more comfortable than the complete
denture wearer because positive support is provided by dental structures designed to resist
occlusal forces.
7. Horizontal and torque forces are reduced.
8. Preservation of Alveolar Bone through tensile stimulation of periodontal ligament.
Textbook of Complete Denture Prostheses by Sarandha D. L.

Drawbacks of overdentures
Overdentures if properly designed and constructed, have very few
drawbacks:
1. Since overdentures cover all gingival margins, high standards of plaque
control and denture hygiene are essential.
2. The overdenture treatment requires endodontic and periodontal therapy
along with root surface preparations. As a result cost is higher than
conventional complete dentures.
3. they are inherently weaker than complete dentures made in similar
manner, due to space occupied by abutments and the superstructure.
However, the loads applied to it are likely to be greater.
4. Increased bulk compared to fixed and removable prostheses.

Indications
• Badly worn teeth
• Few natural remaining teeth
• Poor prognosis for routine CD
• Congenital or acquired intra oral defects
• Mandibular arch (where bone loss is more rapid)
• Post traumatic or post surgical cases
• Severe attrition and loss of VD
• Young patient
• Cleft palate causing large free way space
• Hypodontia

Contraindications
• High caries index
• Poor oral hygiene
• Poor prognosis of abutment
• Reduced inter-arch space
• Undercuts
• Absence of sufficient attached gingiva
• Cases where endo and perio treatments are not satisfactory
• Grade III mobility

Based on type of overdenture
(Brewer and Morrow)
Overdenture
Immediate
Transitional /
Interrupt
denture
Remote /
Permanent
Denture

Types of overdentures (Harold W. Preiskel)
1. Transitional overdentures
2. Training over dentures
3. Immediate replacement overdentures
4. Definitive prostheses

According to method of abutment
Preparation (Heartwell)
Overdenture
Tooth
supported
Non-coping Coping
Short Long
Attachments
Stud Bar Magnet
Implant
supported

Non-coping abutments
• Selected tooth abutments are
reduced to a coronal height of 2 to
3mm and then contoured to a
convex or dome shaped surface.
• Most teeth require endodontic
therapy and in final step are
prepared conservatively to receive
an amalgam or composite type of
restoration.
Non-coping abutments with
amalgam restoration
Syllabus of Complete Dentures by Charles M. Hartwell, Arthur O. Rahn

Advantages and indications:
• Cheapest, simplest and least space consuming
• Ideal in cases during maturation of the edentulous ridges following
immediate insertion technique, or while gingival margins are being
established after mucogingival surgery.
• This approach may also be used to evaluate questionable teeth or the
cooperation of the patient.

Contra-indications
• Should not be used on long term basis when the opposing teeth are
natural dentition.
• Should not be left opposite to bare root surfaces (dentin-to-dentine
contact may produce high rate of wear.
• Should not be used for a very long time basis unless a very highly
polished surface has been achieved.

Abutments with copings
• Cast metal copings with a
dome-shaped surface and a
chamfer finish line at the
gingival margin are fabricated
and cemented.
• There are two types of copings:
• short coping
• long coping.

Short copings
• Short cast copings are 2 to 3 mm
long and normally require
endodontic therapy because the
required coronal root reduction
would expose the pulp.
• Attached to the cast coping is a
post fitted to the canal. For this
reason canals should be obturated
with soft gutta percha-like material
rather than with metal points.
Short cast gold copings

Advantages
• Significantly increases crown-root ratio.
• Reduced lateral loads and minimum space occupied.
• The strength of the denture is virtually unaffected.
Disadvantages
• Although they provide good support, their role in retention is
negligible.

Indication:
• Lack of root support
• Lack of vertical space
• May be used in conjunction with immediate replacement
overdentures.

Long copings
• Long cast copings are normally 5 to 8
mm long. An attempt is made to
circumvent endodontic therapy by a
conservative reduction of coronal tooth
structure.
• The end result is a long ellipsoid-shaped
coronal coping and a larger crown-root
ratio.
• Consequently, long cast copings require
a greater level of osseous support. And,
not infrequently, endodontic therapy
instead of being obviated is simply put
off till a later time.
Long gold abutment copings

Advantages
• Improved retention
• Provides more versatility to treatment options
Disadvantages
• More space consuming and weaken the denture
Indication:
• Awkwardly distributed abutments.
• As inner layer of telescopic prosthesis

Abutments with Attachment
• According to GPT-9, an attachment is defined as “a mechanical
device for the fixation, retention and stabilization of a prosthesis. It
includes frictional, internal, intra-coronal, extra-coronal, key-key way,
parallel, precision and slotted types.”
• The objective of any attachment is to improve fixation and/or
retention of the denture base.
• Most attachments are secured to abutment by a cast coping.
• Consists of two parts: male and female.

Requirements for the attachments
• Low caries index
• Sound periodontal health
• Proper bone support
• Proper home care
Precision attachments in Dentistry by Harold W. Preiskel

Disadvantages of attachments:
• Takes more time
• Expensive
• Difficult to construct
• Difficult to repair
• Requires careful manipulation by the patient (thus not recommended
for mentally and physically challenged patients).

Types of attachments:
• Rigid attachments:
• Does not allow movement of the denture base.
• Provide adequate retention.
• May induce more torque on the abutments.
• Resilient attachments:
• Allows some control of movements.
• Induces less torque on abutments.

1. Stud attachments
Its is the simplest of all attachments.
It consists of two parts:
• The stud (male component): usually
attached to a metal coping cemented
over prepared abutment.
• Housing (female component)
embedded in the fitting surface of the
overdenture.

Extra-radicular stud attachments
• Male element projects from the root surface
• The stud is attached to the metal coping cemented over the prepared
abutment, while the housing is embedded in the fitting surface of the
denture.
Gerber Ceka Rothermann

Intra-radicular stud attachment
The stud is attached to the
fitting surface of the
denture and the housing is
incorporated in the
abutment.
Zest Anchor
Advantage Disadvantage
Overcomes any space
problem
Leverage to the abutment
tooth is reduced
Attachment procedure is
simple
Due to flexibility of nylon,
parallelism of the abutment
teeth are no necessary.
Susceptible to caries, as
there is no coping
Nylon stud may bend,
causing difficulty of seating
the denture. This may reqire
frequent revisits for
correction.
Eating food without the
overdenture may cause
food lodgment in the female
part.

Guidelines for stud attachments
• Attachments should be aligned to each other
• Should be in line with the path of insertion of the denture
• Up to 10° divergence can be tolerated
• Contra indicated in significantly divergent roots or implants
• One stud on either side of the arch is sufficient. Simple copings may be
placed on the other roots.
• Studs on adjacent roots are not advised due to difficulty in maintaining
hygiene.
• Increasing the number of studs do not always increase retention, it may
contribute to improved stability but will definitely weaken the denture
base.

Bar attachments
• It consists of a bar contoured to connect abutment teeth together,
run parallel and overlie residual ridge.
• They are soldered to the copings and can be made of metal or plastic.
Purpose of using bar attachments:
• Splinting of abutment teeth
• Retention and support to prosthetic appliance
• Spreads loading

Disadvantages of bar attachments
• They increase torque.
• Plaque control is difficult
• Relining them is complicated.
• Higher bulk of the bur and related attachments
• Vertical and buccolingual space requirements limits their applications.
• They demand greater oral hygiene maintenance from the patient.

Bar units
• They are rigid and there is no
movement between bar and
sleeve.
• They transmit occlusal stresses
directly to the abutments.
• Thus they are tooth borne.

Bar joints
• They are resilient in nature.
• Allow some rotational
movement between bar and
sleeve.
• Utilize support both from
residual ridge and abutment.
• Thus both tooth and tissue
borne.

Important bar attachments
• Haden bar
• Dolber bar
• Baker clip
• Ackerman clip and CM clip
• King connector

Magnetic attachment
• Detachable keeper element
• Generally made of stainless steel
and is fixed to abutment teeth by
cementing or screwing.
• Denture retention element
• Has paired, cylindrical SmCo
magnets axially magnetized and
arranged with their opposite poles
adjacent.

Diagnosis and Treatment planning
Dentist’s
perception of
the patient’s
needs and
wishes relative
to treatment
Patient’s
perception of
their own needs
and wishes
relative to
treatment
Effective
communication

Requirements for a proper diagnosis
• History
• Examination
• Articulated diagnostic casts
• Full mouth radiographs
• Overall patient concerns

Treatment planning

Patient selection
• Possibility of fixed or removable partial denture
• Endodontic therapy
• Periodontal condition of the abutment teeth
• Caries
• Young patients
• Location of abutment teeth
• Economics
Essentials of Complete Denture prosthodontics Ed 3, by Sheldon Winkler. Pg. no. 513

Factors
influencing
the selection
of abutment
teeth
Selection
of
abutment
teeth
Periodontal
status
Location
Endodontic
status
Mobility
Cost

Periodontal status and mobility
• Ideally the tooth should have minimal mobility, have
acceptable bone support and be responsive to
periodontal therapy.
• Presence of circumferential band of attached gingiva is
absolutely necessary.
• Compromised teeth with good treatment prognosis are
suitable candidates even when horizontal bone loss is
present.
• Slight tooth mobility with horizontal bone loss is not
contraindicated because after preparation of the
abutments, with decrease in C-R ration, mobility also
reduces.
• Vertical bone loss, especially when accompanied by
Grade II or Grade III mobility, is contraindicated for
selectin as abutment.

Abutment location
• Ideally two teeth per quadrant should be present.
• Tripod is most favorable form for support and stability.
• At least one tooth should be there per quadrant.
• Isolated teeth are preferred to adjacent teeth because the interdental
areas are difficult to clean and thus susceptible to gingivitis.
• Mandible:
• Anterior mandibular ridge is most vulnerable to Residual Ridge Resorption.
• Canines and premolars are regarded as abutments for overdentures.
• Maxilla:
• Central incisors are ideal as overdenture abutments (protect premaxilla)
• Canines are next (longest root)
• Lateral incisors (widely spaced, facilitating plaque control.

Endodontic status
• Preserve teeth that are already endodontically treated.
• Usually anterior teeth are preferred as they are easier to prepare and
economic too.
• Whenever pulpal recession to the extent of calcification has occurred,
endodontic treatment usually can be avoided.

Endodontic status
• In 1990, Ettinger showed that the most
common cause of abutment failure was vital
teeth developing periapical lesions as a
result of pulpal necrosis (53.8%)
• According to Zarb 13th edition, after 5-6
years, about 10% of abutment teeth
supporting overdentures were lost:
• Periodontal disease – 70%
• Caries – 25%
• Endo complications – 5%

• Patient is motivated to maintain adequate oral hygiene to prevent
loss of the abutments.
• Patients must clean all exposed dentin and use 0.4% stannous
fluoride daily.

Preparatory phase
• An immediate clasp less denture is
fabricated to replace all missing and
hopelessly involved teeth for esthetic
reasons, as well as retain jaw relations.
• The hopeless teeth are removed and the
removable prosthesis (immediate clasp
less denture) is inserted.
• During the healing period, the endodontic
and periodontal treatments are
undertaken.

Tooth preparation
• Sufficient tooth structure is removed to
provide favorable crown root ratio.
• Crown length is reduced to a level of up to
2mm above the gingival crest and a
chamfer like margin is extended slight
beneath the free gingival margin.
• The preparation is tapered towards the
occlusogingival direction.

Tooth preparation
• Optimal abutment
preparation has the
following features:
• Simple
• Short
• Convex
• Dome shaped
• Chamfer finish line

Impression for the denture.
• The same steps are
used as of
conventional CD.
• Preliminary
impression
• Border Molding
• Final Impression.

Coping fabrication
• An accurate impression of the abutment is
made and a die is poured.
• Wax pattern is prepared for the coping.
• The coping is casted.
• The polished coping is cemented to the
tooth.
• Instructions rea provided to the patients
about home care of abutment teeth.

Recording maxillomandibular relations
• A facebow transfer is used to relate the maxillary cast to the
articulator.
• Jaw relations and phonetics are verified at the time of try in.

Tooth selection:
• Artificial teeth placed over the
abutment teeth should be acrylic
resin.
• When the opposite arch has:
• Gold occlusal surface: occlusal surfaces
of the artificial teeth should be acrylic
teeth or gold (preferably gold).
• Restored with porcelain: porcelain
artificial teeth are preferred.
• Natural teeth: gold occlusals are
preferred, otherwise acrylic.

Denture try in
• Verify jaw relation records.
• Make eccentric jaw relations
and adjust the articulator.
• Assure esthetic acceptance
from patient.
• Phonetic acceptability is
verified.

Laboratory procedures:
• Contouring wax
• Flasking of denture
• Elimination of wax.
• Preparation of resin.
• Packing
• Relief for marginal gingiva.

Denture insertion
• Review instructions in denture use and
care.
• Disclosing paste is used to locate contacts
between female and male members.
• Evaluate the tissue side of the denture
base and borders for pressure areas and
over extensions.
• Perfect the occlusions by remounting and
selective grinding.
• Patient is placed in recall system.

Submerged vital roots
• Selected vital roots are reduced to 2mm below the crestal bone and
then covered by the mucoperiosteal flap.
• Still in experimental stage.
• Theis method is attempted as an innovative method to prevent basic
problems like caries, gingivitis and periodontitis.
• Major post operative problems are:
• Dehiscence over retained roots, and
• Pulpal pathologies.

Summary
• Against a conventional complete denture after extraction of all teeth;
an overdenture is an excellent viable alternative.
• Overdentures not only provide moral boost to patients but also
provides excellent stability and retention.
• They also help to preserve the residual ridge height.
• Emphasis must be placed on proper patient selection, patient
motivation, detailed home care instructions and frequent recalls.

References
1. Overdentures Made Easy by Harold W. Preiskel
2. Textbook of Complete Denture Prostheses by Sarandha D. L.
3. Precision attachments in Dentistry by Harold W. Preiskel
4. Syllabus of Complete Dentures by Charles M. Hartwell, Arthur O.
Rahn
5. Overdentures and telescopic prostheses by Harold W. Preiskel
6. Essentials of Complete Denture Prosthodontics by Sheldon Winkler
7. Ettinger RL, Qian F. Abutment tooth loss in patients with
overdentures. J Am Dent Assoc. 2004 Jun;135(6):739-46; quiz 795-
6. doi: 10.14219/jada.archive.2004.0300. PMID: 15270156.
8. Glossary of Prosthodontic terms – Edition 9

Tooth-supported overdentures guide

Tooth-supported overdentures guide

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