History, types, indications and contraindication and advantages and disadvantages of all type of precision attachments.

1. Presented By:
Dr. J Koshy Joseph

2.  Introduction
 History
 Definition
 Classification
 Indications
 Contraindications
 Advantages
 Disadvantages

3.  Selection of the abutment teeth
 Requirement of the abutment teeth
 Selection of the retainer
 Selection of the attachment
 Intracoronal attachment
 Precision / Semi precision attachments
 Mechanics of retention
 Extracoronal attachment
 Rigid / resilient attachment
 Extracoronal resilient attachment
 O ring attachment
 Broken stress philosophy
 Bar attachments

4.  Stud attachments
 Magnet attachments
 Auxillary attachments
 Conclusion

5.  These are special attachments used in dental
prosthesis which help to achieve better balance
between the functional stability and cosmetic
appeal.
 They are the connecting link between fixed and
removable partial denture as it incorporates
features common to both types of prosthesis.

6. 18th century
Winders design Parr Stair

7. 19th Century
Ash
Dr.Herman, ES Chayes
Chayes Attachment

8.  According to GPT 8
A retainer consisting of 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.

11.  Internal attachments
 Frictional attachments
 Parallel attachments
 Slotted attachments
 Key and Key way attachments

12. I. Based on the method of fabrication
1. Precision attachment (prefabricated types)

13. 2. Semi precision attachments (custom made/ lab
made)

14. II. According to their relationship to the abutment
tooth
1. Intracoronal 2. Extracoronal

15. III. Based on the stiffness of the resulting joint
1. Rigid Attachment 2. Non Rigid attachment

16. IV. Based on geometric configuration and design
1. Key & Keyways
2. Interlocks
3. Ball and socket
4. Bar and clip
5. Hinge
6. Telescopic
7. Puch button
8. Latch
9. Screw units

17.  M. C. Mensor in 1973

18.  Gerardo Beccera and others 1987
Intradental attachments
 Frictional
 Magnetic
Extradental attahments
 Cantilever attachments
 Bar attachments

19.  It improves aesthetics and elevated
psychological acceptance.

20.  Mechanical advantage
 The direct the forces
along the long axis of the
teeth
 Force application is
closer to the fulcrum of
the tooth

21.  In distal extension bases cases – Broken stress
philosophy

22.  Cross arch load transfer and prosthesis
stabilization
 Compared to conventional clasp retained
partial denture
 They are less liable to fracture
 Less bulky and more esthetics
 Better retention and stability
 Less food accumulation

23.  They are complex in design, difficult to
fabricate and judge its clinical application
 Requires minimum clinical crown height of 4-
6mm
 Can’t be used on tooth with limited
faciolingual width.
 Expensive
 Wearing of attachment components

24.  Require high technical expertise
 Requires aggressive tooth preparation
 Co operation and manual dexterity on patient’s
part

25. Removable Prosthodontics
 As a retainer in a removable tooth supported
partial denture
 Stress breakers
 For movable joints in sectional dentures
 Periodontal involvement of the tooth
 Divergent abutment teeth with high survey
lines
 Retainers in tooth supported over denture.

26. Fixed Prosthodontics
 Connector in long span bridges
 To overcome alignment problems where
abutment have differing path of withdrawal.

27. Implant Prosthodontics
 Implant supported over denture
 As connection between the tooth and the
implant.

28. o Poor periodontal support
o Poor crown to root ratio.
o Poor oral hygiene habits
o Abnormally high carious
rate
o Inadequate space to employ
the attachment
o Compromised endodontics
and restorative conditions.

29. Factors:
 Condition of abutment teeth
 Number of abutment teeth
 Location of the abutment teeth
 Periodontal condition
 Crown root ratio
 Periodontical support
 Pulpal Status
 Vitality of the pulp
 Size of the pulp chamber

30.  Clinical Crown Height length.
Maximum attachment
length 6-7 mm
Minimum
attachment length
4mm
Inadequate
attachment
length < 4mm

31.  Buccolingual space requirement

32. 1. Full crown retainers.
2. Partial coverage retainers.
3. Inlays, onlays and pin ledges.
Full crown retainer Partial coverage retainers
Intracoronal attachment
More retentive / rigid
Ideal contours / controlled
Caries protection
Kennedy’s class III partial
denture
Splinted abutment teeth.
Disadvantage – most vulnerable
Inadequate retention
Marginal leakage.

33. Based on the following factors
1. Crown root ratio
2. Clinical crown height
3. Vertical space available
4. No. of abutment used for support
5. Location of the abutment
6. Quality of the bone of the residual ridge
7. Cost
8. Maintenace factors

34.  Intracoronal attachments requires more teeth preparation and
tooth reduction than extracoronal attachment.
 If intracoronal attachment is used where there is insufficient
space, the retainer would be overcontoured resulting to
periodontal problems.
 If space is adequate, intracoronal should be preferred as they
would direct the forces along the long axis of the tooth .
 Extracoronal attachment if employed in areas of inadequate
spaces they can create areas which are difficult to clean,
leading to maintenance problems.
 the lever arm of associated with extracoronal attachments
may not direct all forces along the long axis of teeth.

35.  Resilient attachments allows the functinal
forces to be directed to the tissues and alveolar
ridge.
 Non resilient attachments primarily direct the
vertical functional forces to the abutment teeth.

36.  By Matsuo in 1970,
Red  3-4 mm
Yellow  5-6 mm
Black  7-8 mm.

37. By Dr. MC Mensor 1973

38.  19th Century by Dr. Herman ES Chayes
 Prefabricated type.
 Have no moving parts and are used in all tooth
or implant supported partial dentures.
 Offers excellent retention and aesthetics for
tooth born partial denture.

40. Axial space requirement
 Average dimension is around 1.5mm.
 Minimum of 2mm of reduction in the area of
attachment is essential to keep the final unit
within normal contours.

41. Verticle Length
minimum 3mm
Width in Bucco
lingual direction to be
in the range of 3mm.

42. Commercially available prefabricated
intracoronal attachment

43. Two types of intracoronal attachments are
available
1. Retention is entirely frictional
2. Those where retention is augmented by a
mechanical lock.

44. Frictional Attachments
 Prieskel classified attachments with the
frictional mode of retention as group I.
 The retention provided by the attachment is
dependent primarily on the amount of
frictional surface area contact between the male
and female component. It is therefore necessary
to provide a system that will create maximum
male to female contact.

45. Mechanical Lock
 Preiskel classified attachment that have
mechanical retentive capabilities as group II.
 Involve a spring loaded plunger like device
that engages a recessed dimple or ledge in the
female housing in the abutment teeth.
Eg – The crismani, Stern, Schatzmann attachment.

46. Depending on articular retention :
1. Passive attachment
2. Active attachment
Active friction grip attachment
Active snap grip attachment
3. Locked precision attachment

47. Eg. Passive omega, Beyeler attachment

48.  Active friction grip attachment eg : McCollum,
Crismani attachment.
Incorporate the adjustable spring
mechanism for added retention.
Simplest form is split patrix, so that
part or it forms a leaf spring which
can be opened to compensate for
wear of to give retention. They
function by forcing the part of the
patrix against the matrix thus
increasing the area of contact and
the effort required to separate them

49.  Active snap grip attachment :
The active element consists of a
spring loaded plunger, a split
ring or a U spring which
engages in a prepared pit or
groove example Crismani and
the Schatzman.

50.  They are either bolted by
means of a sliding bolt or
latch, or may be pinned or
screwed together when
fully articulated.
 The basic retaining
mechanism between the
two, patrix and matrix is
friction.

52.  H shaped attachment
 Indications :
1) Fixed removable bridges
2) Removable partial dentures
3) Distal extension partial dentures when cross arch
stabilized is required
 Smaller size is 5 mm by 2.8 mm by 2 mm
 Larger size is 6.4 mm by3.4 mm by 2mm

53.  Retention is by expanding the adjustment slot
in the face of the female. Retention can be
adjusted and is done with an instrument.

55.  The crismani attachment
comes in two forms resilient
and rigid forms.
Rigid types :
Available as with both friction
and mechanical spring clip
retention screw on the male
permits simple replacement of
the adjustment clip for
removable bridges and RPD
where inter arch distance is
limited.

56. Resilient type:
Two types of resilient crismani attachments are
available
 One allowing a pure hinge movement used as a
hinged stress breaker in distal extension partial
denture.
 Other used as a vertical stress breaker or a
combination of both

57.  Intracoronal resilient attachment
 They come in anterior, bicuspid, molar sizes.

58.  Dovetail attachment with both frictional and
mechanical retention

59. Conventional H-shaped design
 No.6 – Bicuspid / molars-
medium proximal contact
attachment.
 No.9- Anteriors -small proximal
contact attachment.

60.  Ney lock attachment : One
piece design with gingival
retentive.
feature – latch retained
 Ney – loc split lingual
attachment : Modification of
No. 9 attachment. These
attachments have extra wide
reinforcing plate for use in
the lingual surface of
pontics.

61.  Ney’s MS attachment –
Neys minimal space
attachment consist of male
and female plastic burn
out patterns, paralleling
mandrel is pre-attached to
the male pattern

63.  Introduced by Henry R Boos in early 1900s
 Modified by F Ewing Roach in 1908
 Retaining devices outside the normal contour
of the attachment tooth.
 They provide only retention.
 Distal extension partial denture
 They reduce the tresses on the abutment teeth
and transfer them to the denture bearing areas.

64. Boitel 1978
Rigid attachment Hinged attachment Resilient attachment
ERA
They do not allow any
rotation of the partial
denture in function
Offers a stress breaking
action to the distal
extension bases
Permit limited amount
of movement of the
denture base (for Class I
partial situation)

65.  Do not alter the normal contour of the abutment .
 Its valuable in situations where the abutment teeth
are short.
 Gives greater retention by including lock screws
and latches .
 Easier for the patient to insert and remove.
 Obviate the risk of over contoured restoration, in
the distal portion of the crown which can result in
accumulation of plaque, resulting to gingivitis and
periodontitis and carious breakdown .

67.  No occlusal stability
 improper control of force distribution between
dentulous and edentulous areas.
 Maintenance problems
 Bulky and break or wears
 Rebasing problem
 Encroachments on the gingival papilla- when
attachments used are too large for the height of
clinical crowns

68. Pin tube attachment:

70. Advantage Disadvantage
Effective retaining device Requires more than 4mm of vertical
height
Length of the attachment interferes with
the position of the tooth.

71.  Frictional retention
 Mechanical locking types

72. Indication :
 Mainly used for the distal extension
removable partial dentures in which a stress
breaking type of retainer is desired.

73.  The loading of the distal extension will result in
rotation and torquing of the abutment tooth,
when the components of an attachment are
rigidly connected ,this may result in damage to
the periodontium.
 Hence, non-rigid or stress breaking attachment
must be positioned between the abutment and
extension bases within the removable partial
denture. These attachment permit vertical,
horizontal or rotational movement of the
denture base relative to the abutments.

74.  Mensor stated that the stress can only by
selected, altered or blocked and hence it is
preferable to call them as stress directors.
 Stress distributors mechanism of stress director
/ stress breaker is to:
 Allow for vertical movement.
 Allow for horizontal movement.
 Allow rotational movement or
 The combination of above three.

75.  Rationale of stress breaker – The amount of
movement should be restricted to only
displaceable tissue.
1. Opponents of this philosophy believe that stress
director attachment allow the application of
excessive force to the residual ridge, causing
premature resorption of the denture bearing area.
2. Also stress director attachments are thought to be
mechanically more complex than rigid attachment
and may be subject to increased wear and
breakage.

76. Design of stress breakers was given by Chayes
and later improved by McCollum.
 Eg : Crismani, Dalbo AS052, Ney stress
breaker, Stern attachment ,Ceka.

77. 1. Stress director allows the occlusal forces to be
directed primarily to residual ridge.
2. Occlusal forces on teeth are minimized.
3. Stress directors incorporating an instant return
spring like device which allows the ridge to
return to its resting state when the teeth are
not in contact.

78. 1. Increased rate of bone resorption and trauma.
2. There is inadequate distribution of occlusal load
on the abutment teeth.
3. Occlusal contacts are more difficult to maintain in
distal extension base prosthesis.
4. Instant return spring like device have a tendency
to fatigue and lose their effectiveness.
5. Space between components sometimes open in
function leading to food entrapment.
6. More complex lab procedures.

80.  In function, the tissues of the denture bearing
areas are displaced into their functional form
and the vertical stops of the attachment contact,
resisting further occlusal forces.
 Pros: they prevents or retards residual ridge
resorption
 Cons: they allow only vertical movement but
no rotational movement of the base, which may
lead in producing adverse forces on the
abutment teeth.

81. 1. ASC52 attachment

82.  Ney’s distal stress breaker

83.  Crismani attachment / non resilient type.

84.  Dalbo

85.  Ceka

87. Advantage :
 Become very popular due to its ease of
replacement.
 Slight amount of flexibility it allows.
They provide vertical resilency of 0.4mm with
universal joint hinge action which makes it ideal
for stress breaking distal extension RPDs.

88. ERAs for RPD are of two types
1. Standard
2. Reduced Vertical. Male part is 0.5mm shorter
than of standard types, female of the same
dimension.

89.  Type of stud attachment

90.  Indications
1. Removable prosthetic retention device
2. Overdenture supported by endosteal implant
Advantages:
1. Ease in changing the attachment
2. Wide range of movement
3. Low cost
4. Different degree of retention.
5. Elimination of time/cost of a superstucture

91. O-rings are made up of material
1. Silicone.
2. Nitrile.
3. Flucocarbon.
4. Ethylene propylene.
More commonly used is nitrile
 High tensile strength and
 High abrasion resistance.

92.  Overcoping/over crown: Telescopic crowns
 Most basic precision attachment
 Thin walled coping cemented in place on the
abutment tooth permits an overcoping attached
to the removable partial denture to fit over it
and provide based on a frictional fit.
 This gives excellent lateral stability and solid
occlusal stop support. And some degree of
retention for the partial denture.

93.  Advantage:
Vertical stop.
Frictional retention
Most effective when used in combination with
other attachment systems.
Few stud attachments are entierly rigid since their
size makes it difficult to prevent a small amount
of movement.

94.  Patrix: stud shaped
projection soldered to the
cast post.
 Matrix: contained within the
denture base to fit over the
male unit.

95.  There are two basic types.
1. Rigid attachment: to bound unilateral or
bilateral saddle cases
2. Resilient attachment: allows some degree of
movement between the male and female
attachments. Reduces stress on the abutment
roots and used in bilateral free end saddle cases.

96. Rigid anchors Resilient anchors
1)Intro fix MP.
2)Rotherman eccentric
CM.
3)Gerber.
4)Schubiger.
5)Ceka axial attachment
Ceka NV.
6)Micro fix unit.
1)Compact MP.
2)Rotherman resilient.
3)Dalbo, Z cylindrical B
spherical attachment.
4)Dalia bona attachment.
5)Zest anchor.
6)Profix.
7)Pro snap.

97. 1. Extraradicular:
The male element projects from
the root surface of the
preparations or implant
Eg. Microfix.

98. 2. Intraradicular:
Male element forms the part of
the denture bases and engages
a specially produced
depression within the root
contour of the implant.
Eg. Ceka revax

99. Advantages:
1. Provide additional stability, retention and
support while the positive lock of certain units
can maintain the border seal of the denture
2. Ease of adjustment, maintenance and repair.
3. Simple to use by the patient

100.  Largest of the studs
 Available in resislent (allowing
vertical movement) or rigid
attachment (allowing no
movements)
 Patrix has threaded post which
is held on by diaphragm by a
screw attached to a soldering
base onto which is screwed a
retentive cone.
 Matrix consists of retention
spring and ring

102. Disadvantages :
 Complex attachment system.
 Requires more space.
 Maintenance problems.
 It permits very little rotation so torquing of
abutment teeth with alveolar resorption.

103.  Karl Cluyten in 1951
 Extracoronal attachment used as a direct
retainer in partial denture
 Stud attachment is overdenture.
Types
 Ceka NV attachment.
 Ceka Revax attachment.

104.  Metal matrix is attached
to the proximal surface of
the abutment crown
 retainer is metal ring
with an orifice in the
centre of the ring and is
tapered so that the widest
part of the opening is at
the top and the smallest
part is at the lower
surface.

105.  Patrix is adjustable and
snaps into the metal matrix.
Its threaded outside so that
it can be screwed onto the
holding device base ring
which is threaded to
receive the attachment pin.
 The pin is conical in shape
with the tip expanding
shapely into a ball shaped/
spherical projection.

106. Ceka attachment fulfils the requirement of the
circumferential clasp 1) support 2) bracing 3)
retention.
 Upper face of the retainer act as a positive stop
for the necessary stability of the attachment.
 Lateral wall of the retainer which the
attachment pin engages brace the prosthesis
against lateral stresses.
 The rounded tip of the attachment pin function
in the socket of the retainer as the retentive
portion of the device.

107.  Matrix is in contact with
the gingival tissues such
that it allows easy access
for hygiene both under
the matrix and between
the matrix and axial
surface of the abutment
crown.

108. Available as rigid unit / resilient unit :
 The vertical travel allowed by the resilient stud unit
is 0.4 mm as opposed to 0.3 mm of the extracoronal
unit.
 The retention pin / male section is screwed into the
base ring and the base forms the part of the root
diaphragm.
Ceka attachment can be made rigid or resilient by the use
of a spacer.
 The Ceka attachment allows for vertical and rotational
movement
Disadvantages :
 Height and bulk.
 Ability of the male to unscrew from the base requiring
frequent replacement.

109.  Patrix (male post) consist
of soldering plate which is
mounted extracoronally to
the via of which has a
vertical squared column
modified cervically by
provision of substantial
ball / spherical shaped.

110.  Matrix (female post)
consists of socket, the
fingers lamellae it of the
socket are surrounded by a
nylon ring / plastic ring
that protects the lamellae
from becoming blocked by
acrylic resin during
intraoral or laboratory
processing.

111. Ball and socket – smallest / most
popular, usually 4mm high.
 The retention of the unit can be
increased by altering the
positions of the free ends of the
lamellae. Their adjustments are
done by retractable spring
loaded plunger that fits the
internal aspect of the attachment.
 As the instrument is pressed
down to the unit the attachment
lamellae are squeezed inwards
by circular surround of the
adjuster.

112. Divided into two groups-those allowing sight
movement between the components (the “bar
joints”) and second comparatively rigid “bar units”
Bar joints – Permit rotation
Bar units – Rigid.
Eg: Dolder bar,
Hader bar,
Andrews bar
CM rider bar
Ackerman bar, bar/clip or bar/sleeve.
Customized bar
Bakers clips

113. Bar units :
 Bar units are comparatively rigid allowing no
movement between the sleeve and bar.
 Provides splinting of remaining abutment
teeth.
 These bar units are not used for overdentures,
these prosthesis are mainly tooth borne.

114. Indications :
 There are more than four abutment teeth and large
edentulous spans.
 Splinting is required for the remaining teeth for cross
arch stabilization.
 Loss of alveolar bone / tissue prevents construction of
aesthetic fixed partial denture – provides favorable
able aesthetic result (Andrews bar).
 There are edentulous areas with considerable
resorption.
 Bar units provide excellent retention and stability for a
denture while rigidly splinting the abutments.

115. Advantages
 Since bar is positioned
close to the alveolar bone
supporting the teeth
forces applied to the teeth
through the bar exert a far
smaller leverage than
these applied through an
occlusal rest of partial
denture.
 Connecting a group of
teeth reduces the mobility
of the unit.
 Bar is usually attached to
diaphragms on root filled
teeth locking the roots
together and improving
the crown / root ratio
Disadvantages :
Bar prosthesis are difficult to
construct where heavy
occlusal forces may be
applied.
Technical difficulties in
spanning a gap of more than
four units with a bar unit
owing to distortion that can
occur.
Plaque accumulation
Vertical and bucco lingual
requirements-limit their use

116. Bar joint
Attachment mechanism is gold plate U-shaped clip of
various length retained in the resin of the prosthesis or
soldered to some portion of the internal framework.
Resilient clips made of thermoplastic material are
inexpensive and can be rapidly placed by the clinician.
These plastic clips are offered with thin metal retainer
housing that has retentive contours on the inner
surface to retain the clip. They are then held in the resin
of the denture with retentive contours on their entire
surface.

117. Indications :
 They are used as an attachment for a fixed,
removable partial denture.
 As a retainer for both with tooth supported and
implant supported prosthesis.

118. Two types
Single sleeve bar joints Multiple sleeve bar
eg : Dolder bar Eg : Ackerman’s bar

119. Dolder bar
 Egg shaped / pear shaped bar (running just in contact
with the oral mucosa between the abutments) in cross
section that permits a certain amount of rotation of the
prosthesis while still retaining the denture.
 An open sided sleeve is built into the impression
surface of the denture and engages the bar when
the denture is inserted.
 Metal sleeves are secured within the acrylic resin
by the retention tags.

120. Action
 The original aim of the Dolder bar joint design was
to allow a considerable measure of both vertical
movement and rotation around the long axis of the
bar. The bar allows some side to side tilting but
Lateral loads are well resisted ..
 Bar work but when it is positioned approximately at
right angles of the sagittal plane. Dolder has
suggested that this bar can be used where there are
just two teeth or roots on the same side such as
canine and first molar. In this case the bar joins the
two roots and runs along the crest of the ridge. Any
rotation is side ways.

121. Advantages :
 Provide excellent stability and rigidly splint
the teeth.
 The design and construction of bar
attachments can provide the denture with
significant stability and additional retention.
 Provides good retention, stability, support
and cross arch stabilization.

122. Disadvantages :
 Bulk of bar (vertical and buccolingual space
requirement limit the application of bar in many cases;
cannot be used universally).
 Plaque accumulation around the bar (Bar attachment)
requires more plaque removal skill on the part of the
patients.
 Resilient attachment have the disadvantage of wearing
more quickly than the gold plate clips.
 Soldering procedure is necessary and complicates the
treatment.
 These cannot be recommended for patients with
limited manual dexterity.
 The clips either metal or plastic will eventually wear
and will need replacement. In general, plastic clips will
wear much faster than the metal clips.
 Space is required for the bar and sleeve, a thickness of
acrylic resin and for the artificial teeth

123. Hader bar
 Helmut Hader in 1960
 resin / plastic sleeve seats
directly on the bar with
no intervening spacer. As
a result it provides
support as well as
retention.

124. Advantages :
 Prefabricate plastic pattern can be easily
adapted to the edentulous ridge ,can be easily
trimmed according to the case.
 Precise fit, simplicity, versatility.
 No need for soldering.
 Has rotational joint relieves stresses from the
abutment teeth

125. CM rider bar
The CM bar is produced in precisious and semi precisious alloys.
Retention tags of the sleeve projects in the long axis of the bar; a
feature that simplifies relocation procedures.
 Two types of sleeves are manufactured,the most
popular has
 short flanges that do not project below the base of
the bar.
 Longer flanges are employed where the bar has to
be bent in the vertical plane over a short distance.
 Tagging at right angles to the bar is well adapted to
resist rotational forces applied to the sleeve.

126. Disadvantages :
 Requires more bucco lingual space – difficulty
with the arrangement of artificial teeth.
 Relocation is difficult.

127. The Ackerman bar :
 Ackerman bar of different
cross sections are available
oval, circular cross section.
Circular cross section is
not versatile as it can be
bent in all planes.
 Multiple sleeve bar joints
are more versatile than the
single sleeve units but the
bars seems to have slightly
less rigidity.

128.  A range of different types of alloys is used in the
manufacture of attachments; melting points are
generally between 8500C at lower end and 14500C at
the top end.
 Alloy of lower melting point – when the attachment is
used in conjunction with gold alloy or processed into
the acrylic resin.
 Alloys of higher melting point – when the porcelain is
to be fused to the metal.
 Precious or semiprecious alloy Platinum,
iridoplatinum, gold and platinum, gold and palladium
. Type III and Type IV and used for crown casting.
 Base metal alloys – are also used due to low costs, low
thermal conductivity and high strength.

129.  Samarium cobalt (Sm -co).
 Neodymium iron boron (Nd-Fe-B) – 20%
strong per unit volume than the cobalt –
samarium alloy.
 Samarium-iron-nitride – high resistance to
demagnetization, high magnetization and
better resistance than Nd-Fe-B type magnets to
temperature and corrosion.

130.  Modern design consists of
sandwich design which uses
encapsulated magnetic retainer
– allows the magnets to be very
slightly spaced from the keeper
to accommodate a corrosion
resistant sleeve.
 In sandwich type design one
magnet is placed between two
ferromagnetic plates effectively
act as a split – pole magnet
assembly and also occupy far
less space eg : Mag fit 600

131. Advantages of magnet attachment
 Their smaller sizes and strong attractive forces
allow these to be placed within the prosthesis
without being obtrusive in the mouth.
 Produce constant force (rare magnetic alloyed
attachment) constant retention with no. of cycles.
 Transmit less lateral forces to the abutment teeth
and they cause no tissue damage.
 They do not need complicated coplanar surfaces
and springs which are expensive to fabricate.
 Easy of cleaning / ease of placement by the
patient. Automatic reseating  after denture
displacement.

132.  Easy to incorporate into the prosthesis simplifying
both clinical and technical procedures.
 Bonus for elderly patients, Parkinsonism, arthritic
patient.
 Easy replacement if needed.
 Dissipate lateral functional forces
 Less need for parallel abutments.
 Inherent stress breaking.
 Comparative freedom of lateral and rotational denture
movements.
 Low potential for trauma to the supporting roots.
 Ease of denture relining.
 Each magnet unit has a force of attraction in the region of
200-300g which is maximal. As soon as the denture starts
to move, this force of attraction imparts a degree of
security to the denture, without putting great demands
on the periodontal tissues of the abutment teeth

133.  Disadvantages :
 Magnets show loss of retention due to corrosion or
heat instability. Therefore, require encapsulation
within the relatively inert alloys such as stainless
steel or titanium.
 Poor corrosion resistance to oral fluids when such
casting are breached. Contact with saliva rapidly
brings about corrosion and loss of magnetism
(Thomas R Jacson and Kent W Healey 1987).
 Cant be repaired
 High cost.
 Short track records.
 Cytotoxic effects of the leachants.

134. Clinical usage :
 Removable partial dentures.
 Complete dentures.
 Implant supported prosthesis.
 Maxillofacial prosthesis.
 Overdentures.
Magnetic force :
 Retentive force recommended for single
attachment is 4-10N (408-1020gm).

135.  The precision attachment offers us the
possibility of making prosthesis that are
esthetic, retentive, strong and problem free and
that are undetectable by and will not
compromise the oral health of the our patients.
The clinicians who familiarize himself with
precision attachments will add a new
dimensions to his/her treatment options and
this will also broaden his/her referral base.