precision atttachments forvfpd and rpd

1. PRECISION
ATTACHMENTS

2. 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

3.  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
 Magnets as attachment
 Auxillary attachments
 Conclusion

4. INTRODUCTION

5. • The desire to balance between functional stability
and cosmetic appeal in partial dentures gave rise to
the development of Precision Attachments
• Precision Attachments have always been
surrounded by an aura of mystery.

6. • The use of Precision Attachments for partial denture
retention is
• A practice builder for the better class of dentistry
• It helps to elevate the general standard of partial denture
prosthetics.
• The precision attachment is sometimes said to be a
connecting link between fixed and removable partial denture
as it incorporates features common to both types of
construction.

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

8. 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)

9. Precision – quality or state of being precise
Attachment – Mechanical device for the fixation, retention and
stabilization of dental prosthesis.
Pin slot
chayes
Ceka &
dallabona

10. • PrecisionAttachment (GPT-8) :
• A retainer consisting of a metal receptacle (matrix)
and a closely fitting part (patrix); the matrix is usually
contained within normal or expanded contours of
the crown on the abutment tooth and the patrix is
attached to a pontic or the removable partial
denture framework.
• An interlocking device, one component of which is
fixed to an abutment or abutments, and the other is
integrated into a removable prosthesis to stabilize
and/or retain it.

11. 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.

12. SYNONYMS OFATTACHMENTS
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

13. CLASSIFICATION OFATTACHMENTS
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 patterns

14.  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)

15. 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

16. 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

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

18. 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 abutment

19. 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

20. 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 components

21. 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 performance

22. 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 essential

23.  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.

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

25. 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

26. SELECTION OF THE ABUTMENT TEETH
Factors :
Condition of 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

27. 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

28. 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

29. 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)

30. EM attachment selector (Dr. MC Mensor (1973)
Quick reference
Communication between the dentist
& laboratory technician
105 attachments
30 points of information

31. INTRACORONALATTACHMENTS
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

32. 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

33. 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

34. 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

35. Mc Collum attachment :
H shaped attachment
Single adjustment slot
Retention  expanding the adjustment slot

36. Stern attachment
Stern Gold latch retained
Two adjustment slots

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

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

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

40. 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

41. 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 floor

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

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

44. 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.

45. EXTRACORONALATTACHMENTS
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

46. EXTRACORONALATTACHMENT
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

47. 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

48. RIGID EXTRACORONALATTACHMENTS
Roach attachment (ball and tube attachment)
Oldest attachment
Patrix – round ball
Matrix - tube
Pin and tube attachment
The simplest
Patrix - pin
Matrix – tube

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

50. RESILIENT EXTRA CORONALATTACHMENT
•Dalbo / Dallabona attachment
Assembled
a) Patrix
b) Matrix

51. Dalbo stress breaker
Rotational and Vertical movement
Matrix and patrix

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

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

54. 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”

55. 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 fatigue

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

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

58. Anchorvis attachment
Stern stress breaker

59. 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

60. 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

61. 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

62. 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

63. 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

64. 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.

65. 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

66. 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

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

68. 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 rotation

69. CEKAATTACHMENT
Ceka revax
Extra radicular Intra radicular
Patrix – metal ring
Matrix – attachment pin
(split metal post)

70. SPACER RING
Vertical movement of the
prosthesis

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

72. 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

73. 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

74. 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

75. MOVEMENTS SEEN IN DOLDER BAR
Sagittal rotationRest position Vertical translation
Implant supported over denture

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

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

78. 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).

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

80. 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

81. 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)

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

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

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

85. 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

86. Disadvantages :
Loss of retention due to corrosion or heat instability
Requires encapsulation within inert alloys
Cant be repaired
High cost
Short track records
Limited force transmission - Magnets can slide on their keepers.

87. 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

88. 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.

89. 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

90. SECTIONAL DESIGNS
Individual sections / separate sections : uses mesial and distal
surface of the abutment teeth as guiding planes.
Bolt retain two parts prosthesis

91. Hinged sections : Buccal and lingual path of insertion

92. CONCLUSION