Precision attachments final (2)/prosthodontic courses

PRECISION ATTACHMENTS
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTS
 Introduction
 History
 Definition and synonyms of attachments
 Classification
 Indications / Applications of precision attachments
 Contraindication
 Advantages
 Disadvantages
 Selection of the abutment teeth
 Requirement of the abutment teeth
 Selection of the retainer
 Selection of the attachment

 Intracoronal attachment
• Precision / Semiprecision attachments
• Mechanics of retention
 Extracoronal attachment
• Rigid / Resilient attachment
• Extracoronal resilient attachment (ERA)
• O-ring attachment
 Role of attachment as stress breaker : “Broken stress
philosophy”
 Bar attachments
 Stud attachments (DEB + overdenture attachments)
 Magnets as attachment
 Auxillary attachments
 Conclusion

 One of the purposes in theOne of the purposes in the “Healing Art”“Healing Art” is to preserve andis to preserve and
maintain each bodily organ to its fullest extent. Themaintain each bodily organ to its fullest extent. The
functions of teeth and mouth are as important in dailyfunctions of teeth and mouth are as important in daily
exercises in human endeavor as that of any other part of theexercises in human endeavor as that of any other part of the
body.body.
 We live in a demanding society as standard ofWe live in a demanding society as standard of
education, wealth and leisure rise, so do expectations. Oureducation, wealth and leisure rise, so do expectations. Our
patients are beginning to apply these expectations aspatients are beginning to apply these expectations as
forcibly to dentistry as to any other activity and increasingforcibly to dentistry as to any other activity and increasing
their demand for the high standards of dental care that theirtheir demand for the high standards of dental care that their
wealth can buy and the good appearance that society teacheswealth can buy and the good appearance that society teaches
them to value.them to value.

 In some situations, usually in the anterior segmentsIn some situations, usually in the anterior segments
of the mouth the FPD cannot fulfill the cosmeticof the mouth the FPD cannot fulfill the cosmetic
needs of a patient without imposing hygieneneeds of a patient without imposing hygiene
problems, in that case RPD is most useful. But theproblems, in that case RPD is most useful. But the
clasps on the anterior teeth are not cosmeticallyclasps on the anterior teeth are not cosmetically
acceptable.acceptable.
 The balance between the functional stability andThe balance between the functional stability and
cosmetic appeal is a major challenge to the dentist.cosmetic appeal is a major challenge to the dentist.
A variety of solutions have been proposed in theA variety of solutions have been proposed in the
form of interlocking devices often called “Precisionform of interlocking devices often called “Precision
Attachment” designed to connect the prosthesis toAttachment” designed to connect the prosthesis to
the abutmentthe abutment

GOALSGOALS
 TheThe goalsgoals for fabrication of PA partial denture area asfor fabrication of PA partial denture area as
follows:follows:
 To provide an efficient masticating replacement ofTo provide an efficient masticating replacement of
lost dental organs.lost dental organs.
 To be removable and replaceable without stress orTo be removable and replaceable without stress or
strain on the abutment teeth.strain on the abutment teeth.
 To allow normal anatomic form to the abutment teeth.To allow normal anatomic form to the abutment teeth.
 To be capable of being tissue supported in aTo be capable of being tissue supported in a
controlled mannercontrolled manner

 To allow for various occlusal correction andTo allow for various occlusal correction and
provide many years of comfortable servicesprovide many years of comfortable services
 To be esthetically acceptable and MinimalTo be esthetically acceptable and Minimal
amount of tooth structure removed.amount of tooth structure removed.
 To avoid endodontic procedures and to beTo avoid endodontic procedures and to be
hygienically cleanhygienically clean
 To place minimum amount of strain on theTo place minimum amount of strain on the
abutment teethabutment teeth

Late 19th
century :
Dr.Herman, ES Chayes
First attachment to be available in the general market
“T shaped”
Precision Attachment
(1906)
“H shaped”
Chayes Attachment
(1912)

Precision – quality or state of being precise
Attachment – Mechanical device for the fixation, retention and
stabilization of dental prosthesis.
“A retainer consisting of a metal receptacle (matrix) and a
closely fitting part (patrix) the matrix is usually contained within
the normal or expanded contours of the crown on the abutment
tooth/dental implant and the patrix is attached to a pontic or the
removable dental prosthesis framework”.
GPT-8

Mechanical device – Direct retainer
• They are designed to replace occlusal rest, bracing arm, and
retaining arm of the conventional clasp retained partial denture.
• They function to retain, support and stabilize the removable
partial denture.

SYNONYMS OF ATTACHMENTS
PatrixPatrix MatrixMatrix
FlangeFlange SlotSlot
InsertInsert CryptCrypt
KeyKey KeywayKeyway
Fitting partFitting part ReceptacleReceptacle
Internal attachments
Frictional attachments
Parallel attachments
Slotted attachments
Key and Key way attachments.
 
Male attachments Female attachments

CLASSIFICATION OF ATTACHMENTS
Based on method of fabrication and the tolerance of fit
I. Precision attachment (prefabricated types)
II. Semiprecision attachment (custom made / laboratory made
types)
Prefabricated wax / plastic / nylon patternswww.indiandentalacademy.comwww.indiandentalacademy.com

 According to their relationship to the abutment teeth
Intracoronal (Internal attachment) Extracoronal (External attachment)
 Based on stiffness of the resulting joint
Rigid attachments Resilient attachments (Non rigid)

Based on geometric configuration and design of the attachment.
Key and Keyway
Interlocks
Ball and socket
Bar and clip / sleeve
Hinge
Telescopic
Push button
Latch
Screw units

M.C. Mensor (1973)
Classification according to shape, design and primary area of
utilization of attachment.
CoronalCoronal RadicularRadicular AccessoryAccessory
IntracoronalIntracoronal
ExtracoronalExtracoronal
Telescope studsTelescope studs
(pressure buttons)(pressure buttons)
Bar attachmentBar attachment
(Bar joints and Bar(Bar joints and Bar
units)units)
AuxillaryAuxillary
Screw unitsScrew units
Bar connectorsBar connectors
BoltsBolts
StabilizersStabilizers
BalancesBalances
InterlocksInterlocks

Beccera and others (1987)
Intradental attachments
- Frictional
- Magnetic
Extradental attachments
- Cantilever attachment
- Bar attachment

ADVANTAGES
Improved esthetics and elevated psychological acceptance
Mechanical advantage
- Direct the forces along the long axis of the teeth / more apically
- Force application closer to the fulcrum of the tooth
Reduces Non axial loading
Decreases Torquing forces
Reduces rotational movement of the
abutmentwww.indiandentalacademy.comwww.indiandentalacademy.com

In Distal extension base cases – “Broken stress philosophy”
Reduced stress to the abutment
Stress free rotational/vertical movements
Cross arch load transfer and prosthesis stabilization
Compared to conventional clasp retained partial denture
Less liable to fracture than clasp
Less bulky and more esthetics
Better retention and stability
Less food stagnationwww.indiandentalacademy.comwww.indiandentalacademy.com

DISADVANTAGES
Complexity of design, procedures for fabrication & clinical
treatment
Minimum occlusogingival abutment height (4-6mm)
To incorporate attachment without overcontouring
Enough length of parallel contact
Anatomy of the tooth – Limited faciolingual tooth width
(incisor and canine areas)
Expensive
Complexity of laboratory and clinical procedure
Attachment maintenance (repair or periodic replacement)
Wearing of attachment componentswww.indiandentalacademy.comwww.indiandentalacademy.com

Require high technical expertise – Dentist and laboratory
technician
Requires aggressive tooth preparation
Cooperation on the part of the patient
Difficult to insert and remove
Mentally challenged patient
Increase demand on oral hygiene performance

INDICATION / APPLICATIONS OF PRECISION
ATTACHMENTS
Removable Prosthodontics
As a retainer in a removable tooth supported partial denture
For esthetic concern in the anterior part of the mouth
Stress Breakers – Free end saddles/Distal Extension Base cases (DEB)
– When cantilevered pontic is to be used as abutment
For movable joints in sectional dentures
Periodontal involvement of the tooth
Contraindicates rigid FPDs
Most efficient bilateral bracing and support are essential

 Divergent abutment teeth with high survey lines – parallel path
of placement.
 As a retainers in tooth supported over denture
Fixed Prosthodontics
 As a connector in fixed partial denture construction
(long span bridges)
 To overcome alignment problems where abutments have
differing path of withdrawal.

IMPLANT PROSTHODONTICS
Implant supported over denture
They are used for connection between the tooth and the implant

CONTRAINDICATIONS OF PRECISION ATTACHMENTS
 Poor periodontal support.
 Poor crown to root ratio
 Poor oral hygiene habits
 Abnormally high carious rate
 Inadequate space / room to employ the
attachment
 Compromised endodontic and restorative
conditions

SELECTION OF THE ABUTMENT TEETH
Factors :
Sound abutment teeth
Number of the abutment teeth
Location of the abutment teeth
Periodontal condition – Crown root ratio
– Periodontal support
Pulpal status – Vitality of the pulp
– Size of the pulpchamber

Minimum attachment length
4mm
Inadequate attachment
length < 4mm
Maximum attachment
length 6-7 mm
Axial space requirement
Sufficient clinical crown length – for minimum of 4mm attachment length
Adequate space between the pulp
and the normal contour of the tooth
Buccolingual space requirement
REQUIREMENTS FOR THE ABUTMENT TEETH

SELECTION OF THE TYPE OF RETAINER
Full crown retainers
Intracoronal attachments
More retentive / rigid
Ideal contours
Caries protection
Partial coverage retainers
Kennedys Cl III partial denture
Splinted abutment teeth
Most vulnerable
Inadequate retention
Marginal leakage
Inlays / onlays / pin ledges
Not used for intracoronal attachments
Lack of retention
Marginal caries
Less life

Selection of the attachments
Intracoronal
vs
Extracoronal
Resilient
vs
Non resilient
75 mm in length
Red  3-4 mm
Yellow 5-6 mm
Black  7-8 mm
EM attachment gauge (Matsuo (1970)

EM Attachment SelectorEM Attachment Selector
System :System :
 Mensor, with his EM Attachment selector system, lists 23Mensor, with his EM Attachment selector system, lists 23
attachments in the intracoronal classification. 17 are listed asattachments in the intracoronal classification. 17 are listed as
nonresilient types and 5 as resilient types. They range from anonresilient types and 5 as resilient types. They range from a
maximum length of 5 to 10mm. The EM attachment Selectormaximum length of 5 to 10mm. The EM attachment Selector
system utilizes a colour – coded millimeter attachment gaugesystem utilizes a colour – coded millimeter attachment gauge
to define the vertical clearance available in the edentulousto define the vertical clearance available in the edentulous
region of occluded casts for attachment selection.region of occluded casts for attachment selection.
 The gauge is made of plastic and measures 75mm in length. ItThe gauge is made of plastic and measures 75mm in length. It
is graduated from 3 to 8mm in 1mm increments with ais graduated from 3 to 8mm in 1mm increments with a
corresponding colour code. Red designates 3 to 4mm ; yellowcorresponding colour code. Red designates 3 to 4mm ; yellow
designates 5 to 6mm; and black designates 7 to 8mm.designates 5 to 6mm; and black designates 7 to 8mm.

 The gauge is placed between the occluded casts adjacent to aThe gauge is placed between the occluded casts adjacent to a
tooth that will carry an attachment. The measurement is thustooth that will carry an attachment. The measurement is thus
read numerically and according to colour. The vertical limitsread numerically and according to colour. The vertical limits
measured by the EM gauge are the common area of concernmeasured by the EM gauge are the common area of concern
FOR A CONNECTOR SYSTEM. The available space willFOR A CONNECTOR SYSTEM. The available space will
govern the type of attachment system that can be used.govern the type of attachment system that can be used.
 A closed vertical space will narrow the selection of availableA closed vertical space will narrow the selection of available
or recommended attachments. Where vertical intermaxillaryor recommended attachments. Where vertical intermaxillary
space is abundant, the choice of attachment systems can bespace is abundant, the choice of attachment systems can be
much less restricting. The EM attachment Selector systemmuch less restricting. The EM attachment Selector system
can be used as a guide to attachment selectioncan be used as a guide to attachment selection..

INTRACORONAL ATTACHMENTS
Intracoronal precision attachment
(Dr. Herman E.S Chayes)
Precision attachment
(prefabricated type)
Semiprecision attachments
(custom made)
Conventional attachment
T shaped attachments
Modern attachment
H shaped
attachments
Contact plate
Adjustment slot
Tube
Head
Reinforcing
plate

Beyeler attachment :Beyeler attachment :
Active friction grip attachments :Active friction grip attachments :
 In many ways these resemble passive attachments,In many ways these resemble passive attachments,
but as they are used in situations where thebut as they are used in situations where the
articulation needs to be separated repeatedly eg.articulation needs to be separated repeatedly eg.
Removable bridgework they include a spring, usuallyRemovable bridgework they include a spring, usually
a split patrix design.a split patrix design.
 Used in anterior and premolar regions.Used in anterior and premolar regions.

MECHANICS OF RETENTION
Frictional : Preiskel group I
Retention – Surface area contact
Function of the length – Controlled by height of clinical crown
– Intermaxillary space available
Function of cross sectional dimensions
Mechanical : Preiskel group II
Auxillary mechanical retentive features
Ex. Spring loaded plunger / clips

Passive Attachment :
Patrix and Matrix inter lock in a jigsaw fashion..Retention
depends on shape of the joint, area of contact and accuracy of
fit
Channels of passive attachment may be round / elliptical slides
DEPENDING ON ARTICULAR RETENTION
Passive attachment Active attachment Locked precision attachment
Omega Beyelerwww.indiandentalacademy.comwww.indiandentalacademy.com

ACTIVE ATTACHMENT
Active friction grip attachment Active snap grip attachments
McCollum Crismani Crismani
Mc.Collum active friction grip – used in posterior areas and
available sizes 4mm and 5.5. mm
Crismani active friction grip – available size range 3mm to
7mm used in anterior and premolar areas

Mc Collum attachment :
H shaped attachment
Single adjustment slot
An H shaped attachment indicated for fixed movable
bridgework, removable partial dentures and distal extension
partial dentures when cross arch stabilized.

Stern attachment
Two adjustment slots
H shaped configuration.
This attachment is an intra-coronal, active friction grip
attachment to which a distal hinge block has been added.
Used as a stress breaker attachment and in fixed removal
bridge work and RPDs.

Crismani attachment :
Available as Rigid / Resilient
Rigid crismani attachment
Frictional grip
Mechanical grip
These come in resilient and rigid forms. The rigid types are
available with both friction and mechanical spring clip retention
mechanisms. They come in intracoronal active friction grip as
well as snap grip varieties.
The hinged, resilient type attachment can be used in distal extension
cases.

 This resilient attachment can be used as a verticalThis resilient attachment can be used as a vertical
stress breaker, as a hinged stress breaker, or astress breaker, as a hinged stress breaker, or a
combination of both.combination of both.
 Two types of resilient crismani attachments areTwo types of resilient crismani attachments are
available, one allowing a pure hinge movementavailable, one allowing a pure hinge movement
and the other allowing lateral movement inand the other allowing lateral movement in
combination with hinge movement.combination with hinge movement.

Ney’s attachment :
Latch retained
Conventional
H shaped
Ney loc split
lingual

 Ney attachments are intracoronal snap gripNey attachments are intracoronal snap grip
attachments, available in 2 basic designs, theattachments, available in 2 basic designs, the
familiar chayes with adjustable wings and thefamiliar chayes with adjustable wings and the
neyloc design with gingival retention feature.neyloc design with gingival retention feature.

Bakers attachment
Schatzmann attachment
These are intraconal
nonresilient attachments.
They come in anterior,
bicuspid and molar sizes.
H shaped configuration. This attachment is an intra-
coronal, active friction grip attachment to which a distal hinge
block has been added.
Used as a stress breaker attachment and in fixed removal
bridge work and RPDs.www.indiandentalacademy.comwww.indiandentalacademy.com

Semiprecision attachments
Defined as rigid metalic extension (patrix) of a fixed or removable
dental prosthesis that fits into a slot type key way (matrix) in a cast
restoration allowing some movement between the component”.
- GPT8
Gillete (1923) : The first semiprecision attachment
Zinner (1979)
Locking semiprecision
attachment
Non locking semiprecision
attachment

Louis blatter fein (1969) : Four rest seat preparation
Occlusal form / outline form – controls amount of rotation
Circular Dove tail Rectangular Mortice
(Rigid – locking type) Resilient Some resiliency
(Non-locking type)
Proximal form / side walls – lateral force control
Parallel outline Tapering outline
The angle of the proximal wall with the gingival floorwww.indiandentalacademy.comwww.indiandentalacademy.com

Gingival floor form : serves the function of reciprocation
Flat Inclined Channeled
Added
reciprocation
Mortice occlusal
form
Rectangular
occlusal form

Advantages :
Applied in clinical situations – employing various rest seat
outline forms.
Variation in tooth size and shapes are easily accommodated.
Better crown contour compared to prefabricated type
Disadvantages :
Long term wear is more – softness of alloy used.
No standardization of sizing : Lack of interchangiability of
male and female attachment.
Greater degree of laboratory skill and attention in detail.www.indiandentalacademy.comwww.indiandentalacademy.com

EXTRACORONAL ATTACHMENTS
Introduced by Henry R. Boos (1900)
Modified by F Ewing Roach (1908)
Application
Kennedy’s class I and class II
Boitel (1978)
 Rigid attachments
 Resilient attachments
 Bar attachments

EXTRACORONAL ATTACHMENT
Rigid attachments Hinged attachments
(Stress breaking action)
Resilient
attachments
ERA
O-ring
Advantages :
• No alteration of contour of the abutment crown
• Can be used in short abutment teeth
• Greater freedom in the design
• Ease of insertion and removal

Disadvantages (Wolf RE 1980) :
Lack of occlusal stability
Bulky
Rebasing problems
Improper control of force distribution
Encroachment on the gingival papilla – use of mini attachment

RIGID EXTRACORONAL ATTACHMENTS
Roach attachment (ball and tube attachment)
Oldest attachment
Patrix – round ball
Matrix - tube
Pin and tube attachment
The simplest
Patrix - pin
Matrix – tube

Stabilex attachment
Two retention pins
Disadvantage is increased length
MatrixPatrix
Assembled
Rigid connection between the male and female units. Additional
retention by pins which may be unscrewed and replaced if
necessary by a special screwdriver.
Attachment is bulky, plaque control difficult
> 4mm vertical space required.
Application : Situations where generous space avilable

Conex attachmentConex attachment
Sides provides precise path of insertion that resist rotational
forces. Pins act two types: Providing frictional retention,
mechanical lock.
Modified Conex : Enables operator to screw the removable
section of prosthesis in place. Application tooth supported
prosthesis where adequate plaque control is possible, unilateral
distal extension spaces, small restorations for bounded spaces.
Bracing arms not required because of the generous lateral surface
area of the attachment. www.indiandentalacademy.comwww.indiandentalacademy.com

RESILIENT EXTRA CORONAL ATTACHMENT
•Dalbo / Dallabona attachment
a) Patrix
b) Matrix
These are known as Dalla bona
slide block or Dalbo stud anchor. They
are simple attachments available in non-
resilient, resilient and stress broken types.
They are useful when there is
minimal vertical space available and
rotation, reesilience and retention are
desired.

The attachment consists of a single piece maleThe attachment consists of a single piece male
stud soldered to the coping and a single unitstud soldered to the coping and a single unit
female processed within the denture.female processed within the denture.
Types :Types :
Rigid cylindrical dolla bonaRigid cylindrical dolla bona
Spherical variety (resilient)Spherical variety (resilient)
Stress brokenStress broken
The stress broken version is similar to theThe stress broken version is similar to the
resilient with exception that female housing isresilient with exception that female housing is
longer and incorporates a coil spring.longer and incorporates a coil spring.

Ceka attachment
Was developed by Karl Cluytens, 1951 and improved in 1968
Two types - Ceka NV attachment
- Ceka revax
.
Used as a direct retainer in partial dentures and overdentures
Is rigid and also non rigid category of extracoronal attachments.
According to Waltz 1973 does not seem to have any adverse effect
on health of abutment teeth and surrounding tissues.

ROLE OF ATTACHMENTS AS STRESS BREAKER
Rigid system Non-rigid system
Stress breaker
Broken stress philosophy
Mensor  stress can only be selected, altered or blocked
“Stress director”www.indiandentalacademy.comwww.indiandentalacademy.com

ASC-52
attachment
STRESS BREAKER DESIGNS
This is an example of an extracoronal resilient attachment that
posses universal resilience.
It consists of an extracoronal slide attachment with a spring
activated universal hinge joint and adjustable retention.
It is the smallest stress director in dentistry and is used for distal
extension RPD’s.

Neys distal extension
stress breaker
Ney attachments are intracoronal snap grip attachments.
Available in 2 basic designs, the familiar chayes with
adjustable wings and the neyloc design with gingival retention
feature.

Stern stress breaker
H shaped configuration. attachment is an intra-coronal, active
friction grip attachment to which a distal hinge block has been added.
Used as a stress broken attachment and in fixed removal
bridge work and RPDs.

Extracoronal resilient attachment (ERA) :
(ERA)
Colour coded retention caps
Most flexible White > Orange > Blue > Gray Most rigid
Two types of ERA
Standard
Reduce vertical (ERA – RV) – male part is 0.5mm shorterwww.indiandentalacademy.comwww.indiandentalacademy.com

Matrix Patrix
Use of ERA in
DEB cases
Use in over denture
Yen Chen Ku et al (2000) : ERA provides esthetics, vertical
resiliency, easy replacement of worn dentures
 Vertical resiliency of 0.4mm
 Universal joint hinge action

O-ring attachment
Patrix - post with the groove
or undercut.
Matrix – O-ring synthetic
polymer gaskets
O-ring are made up of
Silicone
Nitrile
Fluorocarbon
Ethylene propylene

Advantages of O-ring
Ease in changing the attachment
Wide range of movement
Low cost
Different degrees of retention
Elimination of the time / cost of the superstructure

STUD ATTACHMENTS (ANCHORS)
“Anchor the roots”
Simplest of all the attachment
Partrix – dowel / post retained restoration
Matrix – denture base of the prosthesis
Classified as :
 Rigid stud unit
 Resilient stud unit
 Extraradicular units
 Intraradicular units
Extraradicular Intraradicularwww.indiandentalacademy.comwww.indiandentalacademy.com

Space requirement of these attachment
is intermediate between dome shaped
coping and thimble shaped coping.
These should be placed parallel to the
long axis of the tooth.

DALBO STUD ATTACHMENT
Rigid unit
Ball and socket unit
(Vertical and
rotational movement)
 ↑ Retention

ROTHERMAN ECCENTRIC ATTACHMENT
It is one of the smallest of stud attachments and hence
requires very little space (average bt. 1.6mm).
It is available in nonresilient and resilient versions.
Simple to use with adequate retention and ease of
maintenance.
Disadvantages :
Chair –side insertion of keyway is difficult.

ZEST ANCHOR ATTACHMENT
Zest anchor is a stud attachment it consists of a metallic
funnel shaped tube that is cemented into the root canal of the
tooth and a polyethylene stud that is attached to the denture base.
The head of the stud squeezes past the construction in the
neck of the funnel to retain the denture on the tooth. It derives its
retention from within the tooth

GERBER ATTACHMENT
This is one of the largest of the stud units.
Provides good retention stability has adjustable
springs and it is readily replaceable.
Disadvantages :
Complex attachment system
Requres more space
Maintenance problems
It permits very little rotational action to
torquing of abutment teeth occurs with alveolar
resorption .

SCHUBIGER ATTACHMENT
Patrix : threaded post / screw
Matrix : recessed collar, cap nut / lock nut
Cut section

BAR ATTACHMENTS
Gilmore clip system (1913) - metal bar with retaining sleeve / clip.
Bar can be attached to the :
Coping or crowns over the vital teeth
Post coping on endodontically treated teeth
Screwed down into the coping (implant system)
Types of bar attachments :
Customised bar
Dolder bar
Ackermann’s bar
CM rider bar
Hader bar
Andrews bar

Two groups of bar attachments :
1) Bar units - rigid
2) Bar joints – permits rotation
Round / circular Oval / egg shaped ‘U’ shaped /
parallel sided bars
Multiple sleeve bar jointsSingle sleeve bar joints
Depending on cross section
BAR JOINTS

DOLDER BAR
Egg shaped bar in cross section
Open sided sleeve
Two sizes 3.5mm x 1.6mm,
3.0mm x 2.2mm
Spacer – degree of movement

MOVEMENTS SEEN IN DOLDER BAR
Sagittal rotationRest position Vertical translation
Implant supported over denturewww.indiandentalacademy.comwww.indiandentalacademy.com

ACKERMANN BAR
Available in different cross
section
Circular cross section – can
be bent in all planes
A short extension of 5mm is carried
behind the most distal root and the sleeve
positioned on this section prevents tendency
for distal part to rise when sticky foods are
chewed. This is recommended where bar is set
an antero-posteriro curve to prevent hinge
rotation and motion.
Multiple sleeve bar joints are more
versatile than single ones except bars that have
slightly rigidity.www.indiandentalacademy.comwww.indiandentalacademy.com

CM BAR
It is similar to circular
Ackermann bar with
diameter of 1.9 and is of
precious and semi-precious
alloys, the latter
recommended for long
spans.

HADERBAR
Helmut Hader in 1960
Available as a prefabricated plastic pattern
Prefabricated plastic pattern are adapted to master cast
according to its contour and cast in alloy of choice .
Sleeves of plastic have to be replaced for adjustments, hence
metal sleeves can be substituted.

Clips with metal encapsulator
Advantage
 Prefabricated plastic pattern – no need for soldering.
 Precise fit, simplicity.

Advantages of bar attachments :
Rigidly splint the teeth
Provides good retention, stability and support
Provides cross arch stabilization
Positioned close to the alveolar bone (exhibit less leverage)
Disadvantages :
Bulk of bar
Plaque accumulation
Wearing
Soldering procedure

MAGNETS AS ATTACHMENT
Since 1950 To retain maxillofacial prosthesis
Alu, Ni, Iron,Cobalt alloy (alnico)
Limited use – larger size
1960 “use of rare earth element” – High field strength
– Can be used in smaller size.
Somarium cobalt (Sm-Co) (Joseph Becker Hoffer 1967)
Neodymium iron boron (Nd-Fe-B) – 20% stronger
Somarium iron nitride – High magnetization
Used for retention of mandibular overdentures (tooth and implant
supported over dentures)www.indiandentalacademy.comwww.indiandentalacademy.com

Gilling’s magnetic attachment
(cobalt somarium alloy magnets)
“Split pole paired magnets”
Closed field magnetic system
Magnetic retainer with magnets
Magnetic keeper

Advantages of magnetic attachment :
Smaller size and strong attractive force
Produce constant force – constant retention
Easy to incorporate into the prosthesis
Automatic reseating
Boon for elderly patients (Parkinsonism, arthritic patient)
Less lateral force to the abutment tooth

Jackson magnetic attachment
(cobalt somarium alloy magnets)
Cemented in keeper Screwed in keeper

Disadvantages :
Loss of retention due to corrosion or heat instability
Requires encapsulation within inert alloys
Cannot be repaired
High cost
Limited force transmission - Magnets can slide on their keepers.

AUXILLARY ATTACHMENTS
 Screw and tube attachment
 Key and keyway / interlocks
 Presso Matic or Isoclip
 Bar connectors
 Attachments for sectional dentures / bolts
Screw and tube attachment

Indications :
To overcome alignment problems
Connecting one restoration of fixed partial denture to another
Allowing the removal of long span fixed partial denture for
repair and examination of abutment.

ATTACHMENT USED FOR SECTIONAL DENTURES
Two part dentures : One part - chrome cobalt base
Second part - removable acrylic flange with teeth
Advantage of superior esthetics and improved retention
Method of union :
Physical interference : Bolt retained prosthesis
Frictional resistance : Split post retained prosthesis

SECTIONAL DESIGNS
Individual sections / separate sections : uses mesial and distal
surface of the abutment teeth as guiding planes.

 For critical analysis of these attachments, the need forFor critical analysis of these attachments, the need for
through knowledge of their principles andthrough knowledge of their principles and
applications may be of help in obtaining a betterapplications may be of help in obtaining a better
insight into their drawback and areas of potentialinsight into their drawback and areas of potential
improvement.improvement.
 The attachment-retainer removable partial dentureThe attachment-retainer removable partial denture
presents a challenge in technical skill andpresents a challenge in technical skill and
understanding of the biomechanics of maxillo-understanding of the biomechanics of maxillo-
mandibular function.mandibular function.
 The main functions of the attachments are retention,The main functions of the attachments are retention,
stress reduction and concealment for estheticstress reduction and concealment for esthetic
purposes. The attachment-retained removable partialpurposes. The attachment-retained removable partial
denture does attempt to return the patient to as neardenture does attempt to return the patient to as near
normal function and appearance as possible.normal function and appearance as possible.

Advanced removable partial dentures. James S. Brudvick
Quint Int. Pub Pg. 115-152.
Contemporary fixed prosthodontics. Rosensteil, Third edition,
Mosby Pub., pg. 543-566.
Overdenture made easy guide to implant and root supported
prosthesis Harold W. Preiskel – George Zarb.
Precision attachments – a link to successful restorative
treatment Gareth Jenkins Quint Publishing.
Theory and practice of precision attachment RPD – James L
Baker Richard J Goodkins.

J Prosthet Dent 1973; 29(5): 494-497
J Prosthet Dent 1973; 29(2): 165-171.
J Prosthet Dent 1987; 58(3): 327-327.
DCNA 1970; 14(3): 595-601.
Quint Int 2000; 31(5): 311-317.
Quint Int 1987; 18(1): 4-51
J Prosthet Dent 2001; 86: 137-42
J Prosthet Dent 1981; 45(1): 37-43.
Int J Prosthet 1990; 3(1): 98-102.
Int J Prosthet 1990; 3(2): 165-173.

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