5-Precision attachments in prosthodontics ppt

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Contents
 Introduction
 Attachment
 History of attachments
 Classification of attachment systems
 Intracoronal attachments
 Extracoronal attachments

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 Stud attachments
 Bar attachments
 Magnetic retainers
 Auxillary attachments
 Attachment selection
 Conclusion

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Introduction
 In the present society, patients approach a dentist for two main reasons;
discomfort or esthetics
 Attachments are used as alternative to clasps in removable partial
denture therapy, which gives both esthetic and functional outcome
 The correct use of attachments may overcome both physical and
psychological problems associated with conventional RPD designs

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Attachment
 A mechanical device for the fixation, retention, and stabilization of a
prosthesis; OR a retainer consisting of a metal receptacle and a closely
fitting part; the former (matrix component) is usually contained within
the normal or expanded contours of the crown of the abutment tooth
and the latter (patrix component), is attached to a pontic or the denture
framework
GPT9

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 Attachments act as stress redirectors and absorbers.Their function is to
preserve soft tissue and bone as well as provide retention
 The direct retention function of precision attachments prove to be more
efficient than clasps
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Kanathila H. et al., An insight into various attachments used in prosthodontics:A review, International Journal of Applied Dental
Sciences, 2018; 4(4): 157-160

History of attachments
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Stair(1886)- Unilateral
RPD employing anterior
and posterior telescopic
abutment restoration
Parr(1886)-
Extracoronal socket
attachment
George Evans(1888)-
precision attachment
retainer system
Bennett (1904), Fossume
(1906), and Gilmore (1913)
- designed bar attachments
as substitutes for fixed
restorations
Chayes(1906),
developed the T-
shaped precision
attachment
Chayes (1912)-
Chayes attachment
Ash (1912)- Split bar
attachment system.
Helmut Hader
(1960)- Haderbar
Boitel(1928)- Rigid,
Resilient (ERA and
O-Ring) and Bar
attachment
Kanathila H. et al., An insight into various attachments used in prosthodontics:A review, International Journal of Applied Dental Sciences, 2018; 4(4): 157-160

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Gillete(1923)- 1st
semiprecision attachment
Gerardo Becerra (1987)-
Intradental (frictional and
magnetic) and extra dental
(cantilever and bar)
attachment
Yen Chen Ku et al(2000)- the
concept of “ERA” (esthetic,
vertical resiliency, easy
replacement of worn denture)

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Classification of attachment systems
1. Based on their method of fabrication and the tolerance of fit between the
components
A. Precision attachment- They are prefabricated machined components
with precisely manufactured metal to metal parts with close tolerance.
B. Semi precision attachment- They are laboratory made or custom
made type. The components usually originate as prefabricated or
manufactured patterns (made of plastic, nylon or wax) or Hand waxed
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Semi-precision attachments:
 A laboratory fabricated rigid metallic patrix of a fixed or removable
partial denture that fits into a matrix in a cast restoration, allowing some
movement between the components; attachments with plastic
components are often called semi-precision attachments even if
prefabricated (not laboratory fabricated)
GPT9

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2. Based on shape, design and primary area of utilization of attachment
(Mensor-1973)
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Mensor MC. Classification and selection of attachments. J Prosthet Dent. 1973; 29:494-97

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Precision attachments
 According to GPT 9- An interlocking device, one component of which is
fixed to an abutment or abutments, and the other is integrated into a
removable partial denture
 Cohn states, “The precision attachment prevents lateral stress to the
periodontium of the abutment teeth when inserting or removing the
denture. It distributes stress vertically to the tooth during function and
stabilizes the abutment teeth against lateral stress”
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GPT9
Zinner I.D. Precision attachments, Full-Mouth Reconstruction: Fixed Removable, Dental Clinics of North America, July 1987,Vol.31, No. 3, 395-415

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Intracoronal attachments
 Flange and slot
 Provide rigid connection between the two sections of prosthesis
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a. Those whose retention is entirely
frictional.
The McCollum intracoronal unit
b.Those whose retention is augmented by a
mechanical lock
The Schatzmann unit.Additional retention
is provided by a spring-loaded plunger
Preiskel H.W. Precision attachments in Prosthodontics:The applications of intracoronal and extracoronal attachments, volume 1, Quintessence books.

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 Most intracoronal attachments consist of a parallel-sided flange engaging a
slot
 Vertical space of at least 4 mm and buccolingual space of 3 mm is usually
required
 Small bounded spaces, with appreciable bone loss, may be restored with
intracoronal attachments
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Making the prosthesis removable simplifies
oral hygiene practice and allows artificial
mucosa to replace missing bone
Preiskel H.W. Precision attachments for partially dentate mouth, Annals of the Royal College of Surgeons of England (I974), vol 55, 294-298

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 Henderson and Steffel have noted that “ the intracoronal attachment has
two major advantages over the extracoronal attachments, which is the
elimination of a visible retentive component and vertical support through
rest seat locked more favourable in relation to the horizontal axis of the
abutment tooth. It provides some horizontal stabilization similar to that
of an internal rest, but some additional bracing extracoronally is usually
desirable”
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Development of intracoronal precision attachments
 Prior to manufacturing of intracoronal attachments, the early attachments
were bent, cut and soldered into shape
 Early intracoronal retainers were split-bar attachment, tube and split-post
attachment, solid-post and tube attachment and the winged lug
attachment
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Winged lug attachment: the male element is made with a strip of clasp gold
gauge no. 22 by doubling on itself.The female box is made using platinum gauge no.
40. An oval shaped plate made out of 38 or 30 gauge platinum; 22-carat gold is
soldered on top of male to prevent food entrapment between male and female
elements

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The Roach attachment: an extracoronal type of attachment based on
the ball and socket principle

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Gollobin and Bernstein’s split-bar
bridge attachment
The split-post and
bar attachment
Iridoplatinum spilt bar with a V-shaped flange.The split-bar ends with a split-post,
to which the bar acts in the relationship of a shank.The combined split bar and
posts fit into a platinum box in the abutment restoration.The end of the spilt bar
attaches to the partial denture

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The Morgan attachment.A precursor of the Chayes attachment,
employing a parallel jig to parallel and hold the attachments in
position while being soldered to the abutment castings

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Preiskel H.W. Precision attachments in Prosthodontics:The applications of intracoronal and extracoronal attachments, volume 1, Quintessence books
The Chayes attachment(1906). Anchorage section exhibits a post with a seam
in the centre. This seam allows it to be expanded or tightened to the hood

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An attachment system designed by
Alexander at the end of 19th
century.
The male sections were joined to the
crowns, the attachments were tapered
and used with a buccolingual path of
insertion for the prosthesis
Preiskel H.W. Precision attachments in Prosthodontics:The applications of intracoronal and extracoronal attachments, volume 1, Quintessence
books

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Retention Surface area of contact between the two parts
Cross-section of male part x length of the male part
Limited as female part should
recess within the
circumference of the tooth
Governed by the
height of the clinical
crown

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Cross-sections of various types of attachments.
The H-shaped flanges are stronger and have nearly double the contact surface
area of the earlier T-shaped flanges.Attachments with circular cross-section are
suitable only for joining two sections of a fixed prosthesis.

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Frictional fit intracoronal attachments with
adjustment potential
 Constant insertion and removal of the prosthesis will cause the
attachments to wear, so that some form of adjustment is desirable
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The male and female parts of the Stern G/A
attachment.

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Crismani series of intracoronal attachments
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The narrower(2.8mm) Crismani unit
features a central groove for
adjustment
Chamfer and tapered
gingival male section to
facilitate insertion

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 The wider Crismani units incorporate a wire clip to increase retention
 Access to the clip is obtained by removing the screw in the male unit
 Failure to tighten the screw correctly will prevent the male unit sliding into
place
 The female unit consist of two depressions for the retaining wire and is
7mm tall.
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a.The redesigned McCollum attachment.
b.The McCollum for use with conventional yellow golds
c.The McCollum for use with bonded gold to porcelain techniques

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 The Ancra intracoronal attachment
unit features an ‘H’ shaped profile with
external frictional flange, while the male
unit incorporates slots either side to allow
for modification of retention.
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The T
-Geschiebe 123 intracoronal
attachment
Cast bracing arm and
external frictional flange

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 The Biloc by Cendres and Metaux, has a
plastic pattern with the female element, that
is burnt out with the wax model the
abutment crown
 The male element is prefabricated of a
platinised gold alloy. The basic ‘H’ shape is
modified with the internal flange resembling
two lobes with a small groove between
them
 Bracing arm is recommended for this unit
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Auxillary retentive features
 Incorporated to provide more retention for a given contact area,
although no extra stability is provided
 A minimum of 4mm vertical space is still usually necessary
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 The Schatzmann series include a spring loaded plunger within the
male part, engaging a depression in the female element
 Applications are limited by their bulk
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The largest of the Schatzmann
series features a dismantling screw
around the spring loaded plunger
Female element include a retraction
groove to engage the plunger within
the male component

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The modified plunger is held in place
by the screw inserted through the
base of the attachment
The smaller Schatzmann attachment
Processing screw to prevent
movement during processing
procedures

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The Stern gingival latch attachment
 The base of the male unit is split and formed in the
shape of a door latch
 The retention is adjusted by opening out the base
of the male unit with a purpose built tool
 Two sizes- standard and miniature
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Other modifications:
 Micro: smallest of the intracoronal attachments with auxillary
retention. Squared lateral surfaces, allowing the buccolingual
dimensions to be reduced
 Dovetail and ES1: modifications of the tagging of the male unit
 Jacket Maintenance System (Stern): male section is covered
by nylon jacket that eliminates wear of either metal components
1. Yellow jacket- frictional retention
2. Red jacket- adds a light latch action
3. Black jacket- features a strong latch action
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The adjustment
instrument for the
Stern G/L attachment

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Friction fit intracoronal attachments without
adjustment potential
 Repeated removal and insertion will cause the attachment to wear-
unsuitable for removable prosthesis
 Useful for joining a series of crowns without a common path of insertion
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Round profiles are useful where
anterior teeth are concerned
Beyeler attachment for use in
posterior quadrants. Offers more
contact surface area

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 Wang CH et al. (2005), observed the connecting rigidities of four precision
attachments, the dovetail slide attachment beyeler, cylindrical slide attachment,
Spang Stabilex and Mini SG with the conical crown retained telescope (CCT)
 The largest of the mesial end displacements when horizontally loaded was as
large as 44.5 µm with dovetail slide beyeler, the same phenomena occurred
with the distal end displacements when horizontally loaded, followed
sequentially by the Spang Stabilex, CCT, cylindrical slide and the Mini SG
 Thus, connecting rigidities of rigid precision attachments are very similar to
CCT, and only the dovetail slide beyeler attachment is too weak to resist
horizontal displacement force
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Wang CH. et al., Connecting rigidities of various precision attachments compared with the conical crown retained telescope, Kaohsiung J
Med Sci January 2005,Vol 21,No 1

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Abutment tooth preparation
1. Survey the diagnostic cast to ensure proper placement of the
required precision attachment for esthetics, periodontal health,
restoration of biologic tooth contours, and an optimal path of insertion
of the RPD
2. Prepare guide planes to avoid an overcontoured restoration on
these surfaces of the subsequent restoration
3. Prepare a box or deep recess to house the precision attachment
rest seat so as to avoid an overbuilt casting
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4. Prepare the entire abutment tooth using a full shoulder with a bevel
type of preparation. When preparing a tooth for any intracoronal
attachment, whether a precision or a semi-precision attachment, the
dentist must deepen the shoulder from the mid-point on the buccal
surface to the midpoint on the lingual surface, on the near-proximal
zone
5. Add grooves or boxes to increase the resistance to dislodgement on
short crowned abutment preparation or on those ravaged by caries or
large previous restorations
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Guidelines for utilization intracoronal precision attachments
 Selected abutment teeth should be splinted together for proper distribution
of forces for use in precision attachment type RPD
 Use of minimum of 2/3rd
of the attachment
 The length of the attachment is more important than the width. A full-
length, narrow attachment is preferable to a short, wide attachment
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 If attachment length is less than 5mm, another type of intracoronal
attachment must be substituted as there will be insufficient length for the
optimal utilization of the precision attachment
 Prepare the abutment tooth sufficiently, so that the rest seat portion is
maintained within the normal confines of the crown contours for proper
periodontal health
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 All of the precision attachments utilized should be of equal length.When
this is not feasible, pairs of precision attachments on similar teeth
bilaterally should be equal length
 At no time should a rest be grounded or relieved to make it fit.To achieve
a proper fit, clinical and laboratory procedures must be followed precisely.
The attachments must be parallel to each other to avoid improper fit,
mutilation, and torquing of abutments
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Uses and advantages of intracoronal precision
attachments
 Connectors: sections of a fixed prosthesis may be joined with precision
attachments to facilitate parallelism of abutment teeth, ease of
cementation and avoidance of torque on full-arch restoration
 Questionable prognosis: when the prognosis of a segment of fixed partial
prosthesis is questionable, this section can be joined to the part of the
prosthesis with a more favourable prognosis by precision attachments. If
this segment should be lost, it can be replaced with an attachment-
retained, removable partial denture
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 Aesthetics (tooth-borne RPD): precision attachments allow for the
construction of an aesthetic partial denture that retains the appliance
dislodging forces without damage to the abutment teeth and aids in
resisting any tendency of the denture to be displaced horizontally. In
addition, the partial denture enables the dentist to achieve a cross-arch
stabilization
 Precision attachments: these have more advantageous force distribution
to abutment
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 Ease of repair: when the rest portion of the attachment fractures, the
appliance can be repaired easily.This is accomplished by selecting the size
and make of the attachment that was originally utilized and fitting this into
the rest seat.
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Disadvantages of intracoronal precision attachments
 Lack of rotational movement
 Complicated clinical and laboratory procedures
 Increased cost to patient
 Limited in use owing to large pulp size and length of clinical crown
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When used properly, intracoronal precision attachments in conjunction
with fixed partial prosthesis offer the dentist as well as the patient an
optimal result in the rehabilitation of the compromised dentition
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Extracoronal attachments
 Unlike intracoronal attachments these units need no space within the
abutment crown and are unrestricted by pulpal considerations.
 They may be employed where buccolingual space is limited-particularly
useful where lower canines are the most distal abutments.
3 groups of extracoronal attachments:
1. Projection units
2. Connecting units
3. Combined units
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Preiskel H.W. Precision attachments for partially dentate mouth, Annals of the Royal College of Surgeons of England (I974), vol 55, 294-298

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Projection units
 Largest and most popular
 Since they project from the abutment crowns, no box preparation is
required but they complicate plaque control
1. Rigid projection units
2. Projection units allowing play between two sections
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•The height of the projection governs the length of the path of insertion,
influences the retention available and its ability to resist rotational loads
around a sagittal axis
•The lateral surface area counteracts side-to-side movements of denture base
•The width affects its strength and also provides bulk for incorporation of
retaining devices

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The shape of the unit should be modified to prevent sliding or
undesirable tilting movements

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Drawbacks of long attachments:
1. Problems of plaque control increase with increase in
length of unit
2. Greater length requires more space within the
prosthesis. If the attachment is not aligned with the long
axis of edentulous ridge, the longer attachment may
produce an unacceptable lingual bulge in the prosthesis
3. Although they do not require large box or shoulder
preparations, some space within the crown contour is
required for the retaining plate

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Rounding the base of the attachment

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The Stabilex attachment
Screwdriver for changing the pins
•Provides extremely effective retention, but is bulky
•Plaque control is difficult as it requires more than 4mm of vertical space.
•Cannot be placed in case limited space availability

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•The Conex attachment. A series of refinement has reduced its bulk,
facilitated plaque control and improved retention
•Two models of retaining pin- frictional retention or an additional
mechanical lock that further improves retention

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Special separation device
Conex adujsting tool

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Additional tagging may be bolted to
the Conex female unit.
Modified Conex
Component parts of
modified Conex
attachment

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The Scott attachment. The projecting
unit may be placed away from the gingival
margins.
This unit may be obtained as
a plastic blank and cut to size
on the master cast
Requirements: abutments of adequate strength and sufficient vertical
and buccolingual space for the attachment

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The Dalbo attachment
The bilateral model The unilateral model
Contact between the vertical surfaces
prevents the distal denture rotating
away from mucosa
Contact between lateral facing
surfaces provides resistance to
lateral forces

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The Shoulder Dalbo
Cut-away view of the Shoulder
Dalbo without occlusal load
Under occlusal load vertical travel is
limited by contact of the shoulder
Metal spacer

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The Pin-Dalbo
Slight lingual twist simplifies
plaque control
The miniature Dalbo
Unilateral model used

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 A study reported by Caputo AP et al. (1981), showed stress patterns
resulting from the use of a Dalbo, Thompson dowel rest and Sterns
attachment with a distal extension type of prosthesis.
 With a single abutment, there was too much stress on the apical one
third of the abutment tooth.
 Most apical stress was with Sterns attachment and least for splinted teeth
with Thompson dowel rest attachment
 If a single abutment tooth was employed, a Dalbo extracoronal
attachment showed the least stress.
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Caputo AP et al., Photoelastic analysis of stress patterns on teeth and bone with attachment retainers for removable partial dentures, J Prosthet
Dent, 46:21, 1981

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The Ceka attachment
At rest Under vertical load
Under rotational load

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The rigid pin assembly 5mm vertical space Modified design with bracing
arm and occlusal rest
600 series (resilient) 600 series for soldering
to denture framework
600 series for burying
in acrylic resin

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300 series- ‘S’ type designed for soldering to the framework
The KS type designed to be buried in the acrylic resin of the denture base
and includes retaining tags that may be bent to reduce space requirement
Attachment bolted to the minor connector of the partial denture
The KS type-yellow gold or SS Base of retention pin bolted
to denture connector

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Mini retaining unit
The ‘OL’ series
The Ceka Lo-Cast attachment
with black plate
Red patterns

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Bracing arm Mandrel for alignment in
vertical plane
Metal frame work surrounds the
attachment simplifying plaque control
and contributes to strength
Special instrument for producing fine
finish to the metal surround of the
attachment
The Ceka adjustment kit
provided for dental surgeons

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Wedged shaped instrument for
increasing retention- move side-to-side
Never lever apart the leaves of the pins

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Connecting units
 These units connect two parts of a removable prosthesis, allowing a
certain limited amount of play
 They have a similar function to a long and flexible major connector, but
act in a more precise and predictable manner
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The Axial Rotation joint.
The small window around the
screw determines the vertical
travel allowed by the joint
For distal extension dentures
The Rotation joint allows no
vertical play between the two
sections of the attachment
For tooth supported dentures
Steiger joints
Metal trimmed only from
the mesio-gingival and
disto-oclusal sections of
the male unit.

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Combined attachments
 These units consist of a hinge connector joined to an intracoronal
attachment.
 Hinge unit is buried within the denture so that when it is in position, the
attachment closely resembles a rigid intracoronal attachment
 Complex, cumbersome and has limited applications
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Combined Crismani unit
Bilateral configuartion- lateral
walls of the projection are
slightly tapered
Unilateral configuration- lateral
walls of the projection are
virtually parallel

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 Daas M. et al. (2008) evaluated the influence of the retention mechanism on
the behavior of a mandibular implant-retained overdenture (IRO) during the
simulation of mastication
 Three foodstuff positions were analyzed for two retention mechanisms,
“resilient” or “rigid”
 The “resilient” configuration provided a wider contact area between the
mucosa of the denture bearing area and the prosthesis. An increase of the
mastication force transiting through the mucosa was also noted and lower
stresses were observed in the bone surrounding implants
 They concluded that the resilient attachments allowed for an increase of the
mastication load transiting through denture bearing surface
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Daas M. et al., complete finite element model of a mandibular implant-retained overdenture with two implants: Comparison between rigid and
resilient attachment configurations, Medical Engineering & Physics 30 (2008) 218–225

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 Wang H et al. (2011), compared the mechanical effects of 2 types of
extracoronal attachments (rigid and nonrigid) in distal extension
removable partial prostheses on the alveolar ridge and abutment tooth
periodontal ligament
 They concluded that stress on the terminal abutment can be reduced by
the use of an extracoronal resilient attachment that allocates more
loads onto the distal edentulous ridge. Lateral force has the greatest effect
on the terminal abutment in distal extension base PRDPs with universal
hinge attachments. Movement of the component parts in the attachment is
most affected by buccolingual loading.
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Wang H et al., Effects of rigid and nonrigid extracoronal attachments on supporting tissues in extension base partial removable
dental prostheses:A nonlinear finite element study, J Prosthet Dent 2011;105:338-346

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 Rivaldo EG et al. (2011), evaluated the retentive ability and weight change
of two extracoronal attachments, one with plastic inserts and the other
with conventional metal-alloy after repeated insertion/removal cycles
 They concluded that metal-alloy precision attachments showed a greater
increase in retentive ability compared to precision attachment with
plastic inserts over time and both precision attachments did not show
weight change after five years of simulated use.
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Rivaldo EG et al., “In vitro” wear behavior of extracoronal precision attachments, Stomatos,Vol. 17, N.33, July/Dec. 2011

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Stud attachments
 These attachments are so called
because the shape of the male units
that are usually soldered to the
diaphragm of a post crown
 Some of these units provide a rigid
connection, others allow movement
between the two sections
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Microflix
Extraradicular- male element projects form the root surface of the
preparation or implant
Prieskel HW. Overdenture made easy A guide to implant and root supported prosthesis, 1996, Quintessence Books

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The Ceka Revax
Intraradicular- male element forms part of the denture base and engages a
specially produced depression within the root contour or implant

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The Revax system, can be employed in conjunction with rigid bar
stabilizer for the retention of implant supported overdentures

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Most attachments need to be
buried within the acrylic resin

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The Zest intracoronal unit with
comprehensive kit
The seating tool and cropping
instrument
Extensive preparation of the
internal aspect of the root

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The ERA system. Color
coded resin units provide
varying degrees of
retention
ERA retainer within an
overdenture
Most flexible white>orange>blue>gray Most rigid

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The Pro Snap by Metaux
Precieux with replacable retention
elements providing 8, 10, 12
Newtons.The male unit is cast on
The Pro Fix-conventional
stud retainer

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The Gerber unit The Locator retention
system. Retention is
provided by a replaceable
resin component within the
female section
Dalbo ‘Elliptical’
stud retention system

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The Rothermann unit

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Selection of stud attachments
 Space must exist for these units to be surrounded by a reasonable
thickness of acrylic resin, otherwise the denture will be weakened
 Restricted buccolingual space-metal lingual connector employed
 Additional space may be provided by osseous recontouring and
mucogingival surgery, allowing the level of attachment to be reduced
 When vertical space is restricted for implant supported prosthesis, select
an alternative and less space consuming retaining system such as a bar
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 The more rigid attachments occupy more
vertical space than the ball and socket variety
 Dome shaped copings occupy the minimum
space and leverages applied must be small
 In class II div 2 malocclusion, retroclined
anterior teeth encroach upon the space
available. Where buccolingual space permits,
attachments for the lower restorations can
be placed 1-2mm lingual to their normal
position
Designs with flattened studs
minimize vertical space
requirements

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Connecting adjacent
copings resist rotational
forces and inclined forces
resolve along the long
axes of the roots
Conflicting undercuts- base
extension must be reduced,
this will compromise stiffness
and retention. A metal
denture base is preferred

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The alignment of stud attachments
3 considerations:
1. The alignment of stud attachments with one
another
2. The alignment of stud attachments with the path
of insertion of the denture
3. The taller the attachment, the more difficult the
alignment may be
 Significant divergence of roots or implants should
be considered contraindication
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The number of attachments
 One stud attachment on each side of the arch,
remaining roots can be covered with simple
copings
 Increasing the no. of attachments does not
increase retention, it may contribute to
improved stability but weakens the structure
and also difficult to clean and maintain
 Exceptions include nylon attachments
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97
11/09/2025
Dummy male component
incorporated in the cast
The dummy Dalbo stud retainer
The dummy Microfix stud retainer
When necessary to locate an
attachment directly to the denture, cut
a vent hole. Self polymerizing acrylic
resin is applied through the hole

98
 Kim S et al. (2015), compare the changes in retentive force of stud
attachments, Kerator blue, O-ring red, and EZ lock for implant overdentures
by in vitro 2-year–wear simulation
 Results revealed the highest value for Kerator, followed by the O-ring and EZ
lock attachments. However, no significant difference was detected between
Kerator and O-ring after 2500 insertion and removal cycles, the highest
retention loss was recorded for O-ring, and no significant difference between
Kerator and EZ lock.
11/09/2025
Kim S et al., Comparison of changes in retentive force of three stud attachments for implant overdentures, J Adv Prosthodont 2015;7:303-11

11/09/2025 99
 Also, Kerator showed the highest retentive force, followed by EZ
lock and O-ring, after 2500 cycles. Based on SEM analysis, the polymeric
components in O-ring and Kerator were observed to exhibit surface
wear and deformation
 Conclusion-After 2500 insertion and removal cycles, all attachments
exhibited significant loss in retention

100
 Aroso C et al. (2016), conducted a study to evaluate the durability of and
variations in the retention force of three implant overdenture stud-type
attachment systems at three different angulations in an aqueous
environment of artificial saliva.
 Three commercial attachment systems were selected for the study: Clix,
Dalbo-Plus and Locator
 The abutments were placed at angulations of 0°, 10°and 20°
11/09/2025
Aroso C et al., Effect of abutment angulation in the retention and durability of three overdenture attachment systems:An in vitro study, J Adv
Prosthodont 2016;8:21-9

101
 Results revealed that the greater angulation of the abutment values were
found to influence the retention capacity of the attachments, the
attachment systems evaluated presented adequate retention for clinical
usage, the fatigue test simulating 5 years of denture insertion and removal
did not produce wear in metal abutments
 Overall, the Dalbo- Plus system provided the best retention followed by
the white Locator system.
11/09/2025
Aroso C et al., Effect of abutment angulation in the retention and durability of three overdenture attachment systems:An in vitro study, J Adv

102
 Mahrous AI et al (2015), compared and evaluated the effect of two
different attachments (locator attachment and ball and socket [B&S]
attachment) on implants and natural abutments supporting structures, in
cases of limited inter-arch spaces in mandibular Kennedy Class I implant
supported removable partial over dentures by measuring the bone height
changes through the cone beam radiographic technology
 The side of the implant-supported partial over denture restored with the
locator attachment showed better effect on bone health around both the
placed dental implant and the main natural abutment as compared with
the B&S attachment
11/09/2025
Mahrous AI et al., Implant Supported Distal Extension over Denture Retained by TwoTypes of Attachments.A Comparative Radiographic
Study by Cone Beam Computed Tomography, Journal of International Oral Health 2015; 7(5):5-10

11/09/2025 103
Bar attachments
 Consist of a bar spanning an edentulous area joining teeth or roots
 The denture fits over the bar and is connected to it with one or more
sleeves
Bar attachment connected
to root filled teeth
Bar attachment connected to
Branemark implant copings

11/09/2025 104
The Dolder Bar Joint, having
single sleeve joint allowing vertical
and rotational movements
Bar unit. The sleeve/ bar
junction is rigid

11/09/2025 105
Complications of bar attachments
 Vertical and buccolingual space requirements limit the applications
 Require more plaque removal skill on the part of the patient than most
other retainers
 Require adequate and equal retention for abutment retainers if
cementation failures are to be avoided
 Requires technical skills together with clinical expertise. Rebasing and
repair can be complicated

11/09/2025 106
Occlusal stops provided as leverage
potential is high when cantilever employed

11/09/2025 107
Bar joints
Dolder bar joint. Open sided single
sleeve
Single sleeve bar joint

11/09/2025 108
Multiple sleeve bar joint
The connection between the
abutments must be rigid
The use of cantilevered
extensions requires at least
four implant abutments.
Small retentive clips
vulnerable to overload

11/09/2025 109
Round/ circular
shaped
Oval/egg shaped ‘U’ shaped / parallel
sided bars
Gilmore Ackermann and
derivative bars- multiple
sleeve systems

11/09/2025 110
Sleeves of Ackermann bar
project buccolingually
Retention tags for Ackermann bar

11/09/2025 111
The C.M. bar Hader bar
Special space maintaining device Special handling device
for the sleeve

11/09/2025 112
Standard abutments can be
employed when implants are only
moderately misaligned
Angled abutments are far from
ideal but connecting them
minimizes the effects of non-
axial loads

113
 Mohammad D.H. et al. (2013) compared two types of attachments (bar
and ball systems) on the basis of the stresses introduced to the
mandibular posterior residual ridge by an overdenture retained by two
implants. He found that the bar-retained overdenture introduced higher
stresses to the posterior mandibular residual ridge compared to the ball-
retained overdenture (0.4 MPa and 0.1 MPa, respectively)
11/09/2025
Mohammad D.H. et al.,The effects of two attachment types on the stresses introduced to the mandibular residual ridge, Quintessence Int,
2013, vol. 44 no. 8, 555-634

114
 Petropoulus V.C. , Mante F.,(2011) compared the retentive forces and strain
energies of the Nobel Biocare standard ball, Nobel Biocare newer generation
ball (Yorba Linda, CA), Zest Anchor, Zest Anchor Advanced Generation
(Escondido, CA), Sterngold-Implamed ERA white, and Sterngold-Implamed
orange attachments (Attleboro, MA) on an implant-retained in vitro
overdenture model
 Results revealed that the Zest Anchor Advanced Generation attachment had
significantly the highest retentive vertical and oblique forces.The Zest Anchor
had the lowest vertical force , and Nobel Biocare Standard had the lowest
oblique retentive force..
11/09/2025
PetropoulusV.C., Mante F., Comparison of Retention and Strain Energies of Stud Attachments for Implant Overdentures, Journal of
Prosthodontics 20 (2011) 286–293 by the American College of Prosthodontists

115
 The Nobel Biocare Standard Ball attachment had the highest strain
energies in the vertical and oblique directions. The Sterngold-Implamed
ERA White and Zest Anchor had the lowest strain energies, in the vertical
and oblique directions
 He concluded that the retentive forces and strain energies of implant
overdenture stud attachments are different and should be considered
during prosthesis selection
11/09/2025
PetropoulusV.C., Mante F., Comparison of Retention and Strain Energies of Stud Attachments for Implant Overdentures,
Journal of Prosthodontics 20 (2011) 286–293 by the American College of Prosthodontists

116
 Silva AS et al. (2015), compared the durability and retention of 4 types of
attachments, Hader Yellow, Hader Red, Ackerman Gold and Ackerman
Stainless Steel, placed over computer aided design/computer aided
manufacturing (CAD/CAM) titanium bars when subjected to different pH
conditions
 All the attachments lost retention (insertion/removal) over time.
 The more acidic pH value (pH 4) caused a significant decrease in the
average values of the insertion and removal forces of all the attachments
11/09/2025
Silva AS et al., The influence of saliva pH value on the retention and durability of bar-clip attachments, J Adv Prosthodont 2015;7:32-8

117
 The attachment with the most stable behavior was the Ackerman
Gold.
 The Ackerman Stainless Steel was the attachment with the highest values
of insertion and removal initially.
 The highest percentage of loss retention after 5400 cycles was observed
in the Ackerman Stainless Steel attachment (pH 4), with 91.47%
11/09/2025
Silva AS et al., The influence of saliva pH value on the retention and durability of bar-clip attachments, J Adv Prosthodont 2015;7:32-8

11/09/2025 118
Magnetic retainers
 The introduction of rare earth alloys with high field strength and an
intrinsic coercivity many times that of earlier alloys allowed the production
of magnets that were not much larger than stud retainers
 The pioneering work of Gillings, at the University of Sydney, developed a
split pole magnet assembly using cobalt samarium alloys.When paired with
a magnetizable alloy keeper, this produced closed field magnetic retention
 The magnet was placed in the denture and the flat keeper on the
abutment root, so that the path of the insertion of the denture was
unaffected by the retainer

11/09/2025 119
 The production of iron neodymium boron magnets in a laser-welded
capsule solved the problem of corrosion
 Since magnetic retainers resist shear loads to a very small extent (10% of
the normal retention force), only a small amount of lateral load can be
transmitted by the actual retainer

11/09/2025 121
The Megafit 600 unit
The Innovadent (Gillings) system

122
 Hu F et al. (2019), conducted a study to evaluate the biomechanical
behaviors of three different types of magnetic attachments, Flat-type,
dometype and cushion-type, in two-implant-supported overdentures by
three-dimensional finite element analysis methods.
 The biomechanical behaviors of peri-implant bone, abutment, and mucosa
were recorded
 Flat-type magnetic attachment exhibited higher levels of maximum
equivalent strain/stress in the peri-implant bone compared to dome-type
and cushion-type attachments under vertical and oblique loading
conditions
11/09/2025
Hu F et al., Comparison ofThree DifferentTypes of Two-Implant-Supported Magnetic Attachments on the Stress Distribution in Edentulous
Mandible, Computational and Mathematical Methods in Medicine,Volume 2019

123
 Oblique loading may play a detrimental role for all magnetic attachments
in strain/stress distribution and denture stability
 Cushion-type and dome-type attachments are better choices in two-
implant-retained mandibular overdentures, especially for patients with bad
bone conditions such as osteoporosis or when a shorter or smaller
diameter implant has to be used
11/09/2025
Hu F et al., Comparison ofThree DifferentTypes of Two-Implant-Supported Magnetic Attachments on the Stress Distribution in Edentulous
Mandible, Computational and Mathematical Methods in Medicine,Volume 2019

124
 Kim H. et al. (2012) conducted systematic review to address treatment outcome
according to attachment systems for mandibular implant overdentures in terms of
implant survival rate, prosthetic maintenance and complications, and patient
satisfaction
 Four studies presented implant survival rates (95.8 - 97.5% for bar, 96.2 - 100%
for ball, 91.7% for magnet) according to attachment system. Ten other studies
presented an implant survival rate ranging from 93.3% to 100% without respect to
the attachment groups.
 Common prosthetic maintenance and complications were replacement of an assay
for magnet attachments, and activation of a matrix or clip for ball or bar
attachments..
11/09/2025
kim H. et al, Attachment systems for mandibular implant overdentures: a systematic review, J Adv Prosthodont 2012;4:197-203

125
 Conflicting findings were found on the rate of prosthetic maintenance and
complications comparing ball and bar attachments. Most studies showed
no significant differences in patient satisfaction depending upon
attachment systems
 The implant survival rate of mandibular overdentures seemed to be high
regardless attachment systems. The prosthetic maintenance and
complications may be influenced by attachment systems. However patient
satisfaction may be independent of the attachment system.
11/09/2025
kim H. et al, Attachment systems for mandibular implant overdentures: a systematic review, J Adv Prosthodont 2012;4:197-203

126
 Sato H et al. (2019), conducted a study to determine the appropriate
attachment and design of a denture base for mandibular implant
overdenture (IOD), the oral mucosa pressure caused by mandibular
implant overdentures was measured using edentulous jaw models with
various attachments
 Locator attachments (LA), ball attachments (BA), magnetic attachments
(MA), and round-bar attachments (R-BA) were tested
11/09/2025
Sato H et al., Oral mucosa pressure caused by mandibular implant overdenture with different types of attachments, J Prosthodont Res (2019)

127
 Under the bilateral load condition, the lower oral mucosa pressure value
with BA was measured, compared to other attachments at all
measurement sites.
 Under the unilateral load condition, the oral mucosa pressure value of BA
was smaller than the other attachments at the measurement site on the
loading side.
 BA has exerted the greatest effects on support and bracing, suggesting
that, BA is suitable for reducing oral mucosa pressure during mastication
11/09/2025
Sato H et al., Oral mucosa pressure caused by mandibular implant overdenture with different types of attachments, J Prosthodont Res (2019)

128
Auxillary attachments
 Usually they are used with other attachments for improving retention. A
variety of attachments fall into this category. They are screw and tube
attachment, key and keyway/ interlocks, press o matic, Sectional dentures,
bar connectors
11/09/2025
Kanathila H. et al., An insight into various attachments used in prosthodontics:A review, International Journal of Applied Dental
Sciences, 2018; 4(4): 157-160

11/09/2025 129
Screw units
 These devices are useful for securing
and dismantling parts of a prosthesis
in the mouth, when there is no
common line of insertion of the
whole
 They are particularly useful for joining
the two components of a telescopic
crown
By incorporating precious
metal threaded sleeve
within the inner coping,
the outer section can be
retained with a screw

11/09/2025 130
Friction devices
 Spring-loaded plungers are commonly employed to increase retention
between the two sections of a telescopic prosthesis
 Split post can be used with sectional dentures

11/09/2025 131
Bolts
 Bolt units are used to connect the two parts of a sectional denture in
the mouth
 Each part of the denture is inserted separately and the patient locks
them together with the bolt

11/09/2025 132
Hinged flanges
 This type of device allows
mucosal undercuts and
interdental spaces to be used
for retentive purposes
A ‘Swing-lock’ prosthesis.
The hinged labial flange
allows proximal spaces to
be used for retention

133
Attachment selection
E.M. gauge:
 Matsuo developed a color-coded millimeter attachment gauge to define the
vertical clearance available in the edentulous region of occluded casts for
attachment selection
 Fabricated using Plastic and measures 75 mm. in length
 It is graduated from 3 to 8 mm. in one millimeter increments with a corresponding
color code:
Red designates 3 to 4 mm.,
Yellow designates 5 to 6 mm.,
Black designates 7 to 8 mm.
11/09/2025

134
11/09/2025

135
E.M. attachment selector:
 Five 8 &1/2 by 11 inch color coded selector cards and a quick-reference
overlay
 Each of the five cards is numbered to correspond with the five
attachment classification groups
 It contains 30 points of information for each of more than 105 different
attachment systems.
 The color code of the gauge corresponds exactly with that of the five
selector cards.
11/09/2025

136
11/09/2025

137
Use of the gauge and selector:
 The gauge is used to establish the height limitation.The proper attachments
is first selected from the classification group; the overlay, which is a
duplication of the slant-line information index, is used for the selection of an
extracoronal attachment and the points of information are read directly
from the compendium card.
 The keyed color-code measurements represent “Max.“-the size available
commercially and “Min.‘‘-the amount an attachment may be reduced
vertically and still maintain its manufactured characteristics.
11/09/2025

11/09/2025 138
Condition Indicated Contraindicated
Distal extension Extracoronal
attachments
Steiger with axial
rotation joint
Intracoronal
attachments
Scott extracoronal
attachment
Tooth supported Steiger with roational
joint
Limited buccolingual
space
Extracoronal
attachments
Ceka attachments
Intracoronal
attachments
Vertical space <4mm Miniature dalbo
extracoronal
attachment
Ceka 700 series
Ceka- mini retaining
unit
Intracoronal
attachments
Stabilex extracoronal
attachment
Ceka attachment

11/09/2025 139
Conclusion
Precision attachments serve the function of retention, stress distribution
and aesthetics successfully. Appropriate selection of attachments, plays a
major role in the success of treatment. Proper maintenance and care by
the patient and regular follow up decides on the long term success of the
attachment and prosthesis. Use of precision attachment strengthens the
aspects of retention and particularly, esthetics when compared to
conventional removable partial dentures

11/09/2025 140
References
 GPT 9
 Kanathila H. et al., An insight into various attachments used in
prosthodontics:A review, International Journal of Applied Dental Sciences,
2018; 4(4): 157-160
 Mensor MC. Classification and selection of attachments. J Prosthet Dent.
1973; 29:494-97
 Preiskel H.W. Precision attachments in Prosthodontics:The applications of
intracoronal and extracoronal attachments, volume 1, Quintessence books

11/09/2025 141
 Zinner I.D. Precision attachments, Full-Mouth Reconstruction: Fixed
Removable, Dental Clinics of North America, July 1987,Vol.31, No. 3, 395-415
 Preiskel H.W. Precision attachments for partially dentate mouth, Annals of
the Royal College of Surgeons of England (I974), vol 55, 294-298
 Mohammad D.H. et al., The effects of two attachment types on the stresses
introduced to the mandibular residual ridge, Quintessence Int, 2013, vol. 44
no. 8, 555-634
 Petropoulus V.C., Mante F., Comparison of Retention and Strain Energies of
Stud Attachments for Implant Overdentures, Journal of Prosthodontics 20
(2011) 286–293 by the American College of Prosthodontists

11/09/2025 142
 Wang CH. et al., Connecting rigidities of various precision attachments
compared with the conical crown retained telescope, Kaohsiung J Med Sci
January 2005,Vol 21,No 1
 kim H. et al, Attachment systems for mandibular implant overdentures: a
systematic review, J Adv Prosthodont 2012;4:197-203
 Caputo AP et al., Photoelastic analysis of stress patterns on teeth and bone
with attachment retainers for removable partial dentures, J Prosthet Dent,
46:21, 1981
 Aroso C et al., Effect of abutment angulation in the retention and durability
of three overdenture attachment systems: An in vitro study, J Adv

11/09/2025 143
 Daas M. et al., complete finite element model of a mandibular implant-
retained overdenture with two implants: Comparison between rigid and
resilient attachment configurations, Medical Engineering & Physics 30
(2008) 218–225
 Mahrous AI et al., Implant Supported Distal Extension over Denture
Retained by TwoTypes of Attachments.A Comparative Radiographic Study
by Cone Beam Computed Tomography, Journal of International Oral
Health 2015; 7(5):5-10
 Kim S et al., Comparison of changes in retentive force of three stud
attachments for implant overdentures, J Adv Prosthodont 2015;7:303-11

11/09/2025 144
 Prieskel HW. Overdenture made easy A guide to implant and root
supported prosthesis, 1996, Quintessence Books
 Wang H et al., Effects of rigid and nonrigid extracoronal attachments on
supporting tissues in extension base partial removable dental prostheses:
A nonlinear finite element study, J Prosthet Dent 2011;105:338-346
 Rivaldo EG et al., “In vitro” wear behavior of extracoronal precision
attachments, Stomatos,Vol. 17, N.33, July/Dec. 2011
 Silva AS et al., The influence of saliva pH value on the retention and
durability of bar-clip attachments, J Adv Prosthodont 2015;7:32-8

11/09/2025 145
 Sato H et al., Oral mucosa pressure caused by mandibular implant
overdenture with different types of attachments, J Prosthodont Res
(2019)
 Hu F et al., Comparison of Three Different Types of Two-Implant-
Supported Magnetic Attachments on the Stress Distribution in
Edentulous Mandible, Computational and Mathematical Methods in
Medicine,Volume 2019

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