Precision attachments final / dental implant courses by Indian dental academy

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

HISTORICAL BACKGROUND
Winder
“Winders design”
Screw joint retention
Parr (1886)
Extracoronal socket attachment
Stair
Telescopic abutment restoration
Ash (1912)
Split bar attachment system

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
Patrix Matrix
Flange Slot
Insert Crypt
Key Keyway
Fitting part Receptacle
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.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

Classification used in literature :
M.C. Mensor (1973)
Classification according to shape, design and primary area of
utilization of attachment.
Coronal Radicular Accessory
Intracoronal
Extracoronal
Telescope studs
(pressure buttons)
Bar attachment
(Bar joints and Bar units)
Auxillary
Screw units
Bar connectors
Bolts
Stabilizers
Balances
Interlocks

Gerardo 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
Rotational movement of the abutmentwww.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 stagnation

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.com

Require high technical expertise – Dentist and laboratory
technician
Requires aggressive tooth preparation
Cooperation and manual dexterity on the part of the patient
Difficult to insert and remove
Visually or manually challenged patient
Increase demand on oral hygiene performancewww.indiandentalacademy.com

INDICATION / APPLICATIONS OF PRECISION
ATTACHMENTS
Removable Prosthodontics
As a retainer in a removable tooth supported partial denture
4 large well rounded abutments are available
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 essentialwww.indiandentalacademy.com

 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 pulpchamberwww.indiandentalacademy.com

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 lifewww.indiandentalacademy.com

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 selector (Dr. MC Mensor (1973)
Quick reference
Communication between the dentist
& laboratory technician
105 attachments
30 points of informationwww.indiandentalacademy.com

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
Rein forcing
plate

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 :
Matrix : Simple channels closes at one end to provide stop
Patrix : Solid slide
Channels of passive attachment may be round / elliptical slides
DEPENDING ON ARTICULAR RETENTION
Passive attachment Active attachment Locked precision attachment
Omega Beyeler

ACTIVE ATTACHMENT
Active friction grip attachment Active snap grip attachments
Locked precision attachment
Attachments bolted by means of a sliding bolt or latch
Pinned or screwed together
McCollum Crismani Crismani
Latch retained

Mc Collum attachment :
H shaped attachment
Single adjustment slot
Retention  expanding the adjustment slotwww.indiandentalacademy.com

Stern attachment
Stern Gold latch retained
Two adjustment slots

Crismani attachment :
Available as Rigid / Resilient
Rigid crismani attachment
Frictional grip
Mechanical  Spring clip

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

Bakers attachment
Schatzmann attachment
Frictional retention
Mechanical retention
(spring loaded plunger & coil spring)

Semiprecision attachments
Semiprecision rest – intracoronal rest seat and resilient lingual arm.
“Laboratory fabricated 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
Rectangular deep rest with buccal and lingual wrought clasps arms
Ira D Zinner (1979)
Locking semiprecision
attachment
Non locking semiprecision
attachment

Louis blatter fein (1969) : Four aspects of 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.com

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

Ney’s MS Intracoronal attachment (circular rest)
Locking Semiprecision Attachments
Neurohr – Williams No. 1 (Mortice rest)

Advantages :
Versatility for 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.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 removalwww.indiandentalacademy.com

Disadvantages (Wolf RE 1980) :
Lack of occlusal satability
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

Conex attachment
(Smaller version)
Stabilex attachment
Two retention pins
Disadvantage is increased length
MatrixPatrix
Assembled
Two types pins
Frictional retention
Mechanical locking

RESILIENT EXTRA CORONAL ATTACHMENT
•Dalbo / Dallabona attachment
Assembled
a) Patrix
b) Matrix

Dalbo stress breaker
Rotational and Vertical movement
Matrix and patrix

Ceka attachment
Developed by karl cluytens (1951)
Two types - Ceka NV attachment
- Ceka revax
Matrix → metal ring retainer
Patrix → Attachment pin
(split metal post)www.indiandentalacademy.com

Functional aspect : Mark E, Waltz 1973
A) Support
B) Bracing
C) Retention
Attachment pin / split post
• Insertion and removal
• Reduces frictional wear
Ceka Revax

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.com

Shohet (1969) Kratochvil (1981)
Low intensity forces on abutment teeth in contrast to rigid
attachments.
Rationale of stress breaker  movement should be strictly only
to displaceable tissue
Disadvantages of stress director :
More complex, increased wear and breakage
Increased bone resorption and trauma
Occlusal contacts difficult to maintain
Spring like device  tendency to fatiguewww.indiandentalacademy.com

ASC-52
attachment
Extracoronal resilient attachment
Patrix and Matrix
STRESS BREAKER DESIGNS

Neys distal extension
stress breaker
Crismani resilient
attachment
“Hinge stress breaker”

Anchorvis attachment
Stern stress breaker

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 shorter

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-SO ring / O-ring attachment
Patrix - post with the groove
or undercut.
Matrix – O-ring synthetic
polymer gaskets +
encapsulator
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 Intraradicular

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)
Nylon ring – protects the lamella
 ↑ Retention – altering the positions
of free ends of the lamella

ROTHERMAN ECCENTRIC ATTACHMENT
Button shaped attachment
Patrix – eccentric cylinder
with undercut or groove
Matrix – Clip or clasp arm
Activation : Bending the
clasp arm towards center
Resilient unit
Rigid units

ZEST ANCHOR ATTACHMENT
Patrix
Polyethylene – Nylon stud
Matrix
Funnel shaped tube
Instrumentation kit
Advantages :
Reduce vertical
space requirement
Loads are
transferred more
apically.www.indiandentalacademy.com

GERBER ATTACHMENT
Resilient gerber Rigid gerber
Largest of the stud unit
Resilient – spring controlled
vertical plane
Patrix – threaded post
Matrix – retention spring and ring
Disadvantages :
Complex attachment system
Requires more space
Permits little rotationwww.indiandentalacademy.com

CEKA ATTACHMENT
Ceka revax
Extra radicular Intra radicular
Patrix – metal ring
Matrix – attachment
pin (split metal post)

SPACER RING
Vertical movement of the
prosthesis

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 www.indiandentalacademy.com

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.com

ACKERMANN BAR
Available in different cross
section
Circular cross section – can
be bent in all planes

CM BAR
 Made up of precious /
semiprecious alloy
 Retention tags in long axis
of the bar

HADERBAR
Helmut Hader in 1960
Available as a prefabricated plastic pattern
Notable feature
 Resin / plastic sleeve
 No spacer- more
support
English, Donnel & Staubli (1992)
Hader EDS system
System with 3mm height (8.3mm).

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

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
Manual dexterity

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)

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

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

Encapsulated magnetic retainer
and magnetic keeper
Assembled attachment
SANDWICH DESIGN
Attractive breaking force  4.9 N (500 gm)

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

Disadvantages :
Loss of retention due to corrosion or heat instability
Requires encapsulation within inert alloys
Cant be repaired
High cost
Short tract records
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.
Bolt retain two parts prosthesis

Hinged sections : Buccal and lingual path of insertion

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.
The bar joint denture Eugere. J. Dolder / Gustav T Duller.
Precision attachments in prosthodontics : overdenture and
telescopic prosthesis volume 2. Quint Pub.

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.www.indiandentalacademy.com

Precision attachments final / dental implant courses by Indian dental academy

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