Precision attachments in prosthodontics/ orthodontics short term courses

www.indiandentalacademy.comwww.indiandentalacademy.com

PRECISION ATTACHMENTS

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com


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

Selection of the attachment


Intracoronal attachment • Precision / Semiprecision attachments• Mechanics of retention

Extracoronal attachment • Rigid / Resilient attachment • Extracoronal resilient attachment (ERA) • O-ring attachment

Role of attachment as stress breaker : “Broken stress philosophy”

Bar attachments Stud attachments (DEB + overdenture attachments) Magnets as attachment Auxillary attachments Conclusion List of references


One of the purposes in the One of the purposes in the “Healing Art”“Healing Art” is to preserve and is to preserve and maintain each bodily organ to its fullest extent. The maintain each bodily organ to its fullest extent. The functions of teeth and mouth are as important in daily functions of teeth and mouth are as important in daily exercises in human endeavor as that of any other part of the exercises in human endeavor as that of any other part of the body. body.

We live in a demanding society as standard of We live in a demanding society as standard of education, wealth and leisure rise, so do expectations. Our education, wealth and leisure rise, so do expectations. Our patients are beginning to apply these expectations as patients are beginning to apply these expectations as forcibly to dentistry as to any other activity and increasing forcibly to dentistry as to any other activity and increasing their demand for the high standards of dental care that their their demand for the high standards of dental care that their wealth can buy and the good appearance that society teaches wealth can buy and the good appearance that society teaches them to value. them to value.


In some situations, usually in the anterior segments In some situations, usually in the anterior segments of the mouth the FPD cannot fulfill the cosmetic of the mouth the FPD cannot fulfill the cosmetic needs of a patient without imposing hygiene needs of a patient without imposing hygiene problems, in that case RPD is most useful. But the problems, in that case RPD is most useful. But the clasps on the anterior teeth are not cosmetically clasps on the anterior teeth are not cosmetically acceptable. acceptable.

The balance between the functional stability and The balance between the functional stability and cosmetic appeal is a major challenge to the dentist. cosmetic appeal is a major challenge to the dentist. A variety of solutions have been proposed in the A variety of solutions have been proposed in the form of interlocking devices often called “Precision form of interlocking devices often called “Precision Attachment” designed to connect the prosthesis to Attachment” designed to connect the prosthesis to the abutment the abutment


GOALSGOALS

The The goals goals for fabrication of PA partial denture area as for fabrication of PA partial denture area as follows: follows:

To provide an efficient masticating replacement of lost To provide an efficient masticating replacement of lost dental organs.dental organs.

To be removable and replaceable without stress or strain To be removable and replaceable without stress or strain on the abutment teeth. on the abutment teeth.

To allow normal anatomic form to the abutment teeth. To allow normal anatomic form to the abutment teeth. To be capable of being tissue supported in a controlled To be capable of being tissue supported in a controlled

manner manner


To allow for various occlusal correction and To allow for various occlusal correction and provide many years of comfortable servicesprovide many years of comfortable services

To be esthetically acceptable and Minimal To be esthetically acceptable and Minimal amount of tooth structure removed. amount of tooth structure removed.

To avoid endodontic procedures and to be To avoid endodontic procedures and to be hygienically cleanhygienically clean

To place minimum amount of strain on the To place minimum amount of strain on the abutment teeth abutment teeth


Late 19th century :

Dr.Herman, ES Chayes

First attachment to be available in the general market

“T shaped”

Precision Attachment (1906)

“H shaped”

Chayes Attachment (1912)


Precision – quality or state of being precise

Attachment – Mechanical device for the fixation, retention and

stabilization of dental prosthesis.

“A retainer consisting of a metal receptacle (matrix) and a

closely fitting part (patrix) the matrix is usually contained within

the normal or expanded contours of the crown on the abutment

tooth/dental implant and the patrix is attached to a pontic or the

removable dental prosthesis framework”.

GPT-8


Mechanical device – Direct retainer

• They are designed to replace occlusal rest, bracing arm, and

retaining arm of the conventional clasp retained partial denture.

• They function to retain, support and stabilize the removable

partial denture. www.indiandentalacademy.comwww.indiandentalacademy.com

SYNONYMS OF ATTACHMENTS

Patrix Patrix Matrix Matrix Flange Flange Slot Slot Insert Insert Crypt Crypt Key Key Keyway Keyway

Fitting part Fitting part Receptacle Receptacle

Internal attachments

Frictional attachments

Parallel attachments

Slotted attachments

Key and Key way attachments.

Male attachments Female attachments


CLASSIFICATION OF ATTACHMENTS

Based on method of fabrication and the tolerance of fit

I. Precision attachment (prefabricated types)

II. Semiprecision attachment (custom made / laboratory made types)

Prefabricated wax / plastic / nylon patterns www.indiandentalacademy.comwww.indiandentalacademy.com

According to their relationship to the abutment teeth

Intracoronal (Internal attachment) Extracoronal (External attachment)

Based on stiffness of the resulting joint

Rigid attachments Resilient attachments (Non rigid)


Based on geometric configuration and design of the attachment.

Key and Keyway

Interlocks

Ball and socket

Bar and clip / sleeve

Hinge

Telescopic

Push button

Latch

Screw units


M.C. Mensor (1973)

Classification according to shape, design and primary area of utilization of attachment.

Coronal Coronal Radicular Radicular Accessory Accessory IntracoronaIntracoronal l

ExtracoronExtracoronalal

Telescope studs Telescope studs (pressure buttons) (pressure buttons) Bar attachment Bar attachment (Bar joints and Bar (Bar joints and Bar units) units)

Auxillary Auxillary Screw units Screw units Bar connectors Bar connectors Bolts Bolts Stabilizers Stabilizers Balances Balances Interlocks Interlocks


Beccera and others (1987)

Intradental attachments

- Frictional

- Magnetic

Extradental attachments

- Cantilever attachment

- Bar attachment


ADVANTAGES

Improved esthetics and elevated psychological acceptance

Mechanical advantage

- Direct the forces along the long axis of the teeth / more apically

- Force application closer to the fulcrum of the tooth

Reduces Non axial loading

Decreases Torquing forces

Reduces rotational movement of the abutment www.indiandentalacademy.comwww.indiandentalacademy.com

In Distal extension base cases – “Broken stress philosophy”

Reduced stress to the abutment Stress free rotational/vertical movements

Cross arch load transfer and prosthesis stabilization

Compared to conventional clasp retained partial denture Less liable to fracture than clasp Less bulky and more esthetics Better retention and stability Less food stagnation www.indiandentalacademy.comwww.indiandentalacademy.com

DISADVANTAGES

Complexity of design, procedures for fabrication & clinical treatment

Minimum occlusogingival abutment height (4-6mm)To incorporate attachment without overcontouring

Enough length of parallel contact

Anatomy of the tooth – Limited faciolingual tooth width (incisor and canine areas)

Expensive Complexity of laboratory and clinical procedure

Attachment maintenance (repair or periodic replacement)

Wearing of attachment components www.indiandentalacademy.comwww.indiandentalacademy.com

Require high technical expertise – Dentist and laboratory technician

Requires aggressive tooth preparation

Cooperation on the part of the patient

Difficult to insert and remove

Mentally challenged patient

Increase demand on oral hygiene performancewww.indiandentalacademy.comwww.indiandentalacademy.com

INDICATION / APPLICATIONS OF PRECISION ATTACHMENTS

Removable Prosthodontics

As a retainer in a removable tooth supported partial denture

For esthetic concern in the anterior part of the mouth

Stress Breakers – Free end saddles/Distal Extension Base cases (DEB)

– When cantilevered pontic is to be used as abutment

For movable joints in sectional dentures

Periodontal involvement of the tooth

Contraindicates rigid FPDs

Most efficient bilateral bracing and support are essential


Divergent abutment teeth with high survey lines – parallel path of placement.

As a retainers in tooth supported over denture

Fixed Prosthodontics

As a connector in fixed partial denture construction (long span bridges)

To overcome alignment problems where abutments have differing path of withdrawal.


IMPLANT PROSTHODONTICS

Implant supported over denture

They are used for connection between the tooth and the implant


CONTRAINDICATIONS OF PRECISION ATTACHMENTS

Poor periodontal support.

Poor crown to root ratio

Poor oral hygiene habits

Abnormally high carious rate

Inadequate space / room to employ the attachment

Compromised endodontic and restorative conditions


SELECTION OF THE ABUTMENT TEETH

Factors :

Sound abutment teeth

Number of the abutment teeth

Location of the abutment teeth

Periodontal condition – Crown root ratio

– Periodontal support

Pulpal status – Vitality of the pulp

– Size of the pulpchamber www.indiandentalacademy.comwww.indiandentalacademy.com

Minimum attachment length 4mm

Inadequate attachment length < 4mm

Maximum attachment length 6-7 mm

Axial space requirement Sufficient clinical crown length – for minimum of 4mm attachment length

Adequate space between the pulp and the normal contour of the tooth Buccolingual space requirement

REQUIREMENTS FOR THE ABUTMENT TEETH


SELECTION OF THE TYPE OF RETAINER

Full crown retainers

Intracoronal attachmentsMore retentive / rigid

Ideal contours

Caries protection

Partial coverage retainers

Kennedys Cl III partial denture

Splinted abutment teethMost vulnerable

Inadequate retention

Marginal leakage Inlays / onlays / pin ledges

Not used for intracoronal attachmentsLack of retention

Marginal caries

Less life www.indiandentalacademy.comwww.indiandentalacademy.com

Selection of the attachments

Intracoronal vs

Extracoronal

Resilient vs Non resilient

75 mm in length Red 3-4 mmYellow 5-6 mmBlack 7-8 mm

EM attachment gauge (Matsuo (1970)


EM Attachment Selector EM Attachment Selector System :System :

Mensor, with his EM Attachment selector system, lists 23 Mensor, with his EM Attachment selector system, lists 23 attachments in the intracoronal classification. 17 are listed as attachments in the intracoronal classification. 17 are listed as nonresilient types and 5 as resilient types. They range from a nonresilient types and 5 as resilient types. They range from a maximum length of 5 to 10mm. The EM attachment Selector maximum length of 5 to 10mm. The EM attachment Selector system utilizes a colour – coded millimeter attachment gauge system utilizes a colour – coded millimeter attachment gauge to define the vertical clearance available in the edentulous to define the vertical clearance available in the edentulous region of occluded casts for attachment selection. region of occluded casts for attachment selection.

The gauge is made of plastic and measures 75mm in length. It The gauge is made of plastic and measures 75mm in length. It is graduated from 3 to 8mm in 1mm increments with a is graduated from 3 to 8mm in 1mm increments with a corresponding colour code. Red designates 3 to 4mm ; yellow corresponding colour code. Red designates 3 to 4mm ; yellow designates 5 to 6mm; and black designates 7 to 8mm.designates 5 to 6mm; and black designates 7 to 8mm.


The gauge is placed between the occluded casts adjacent to a The gauge is placed between the occluded casts adjacent to a tooth that will carry an attachment. The measurement is thus tooth that will carry an attachment. The measurement is thus read numerically and according to colour. The vertical limits read numerically and according to colour. The vertical limits measured by the EM gauge are the common area of concern measured by the EM gauge are the common area of concern FOR A CONNECTOR SYSTEM. The available space will FOR A CONNECTOR SYSTEM. The available space will govern the type of attachment system that can be used.govern the type of attachment system that can be used.

A closed vertical space will narrow the selection of available A closed vertical space will narrow the selection of available

or recommended attachments. Where vertical intermaxillary or recommended attachments. Where vertical intermaxillary space is abundant, the choice of attachment systems can be space is abundant, the choice of attachment systems can be much less restricting. The EM attachment Selector system much less restricting. The EM attachment Selector system can be used as a guide to attachment selectioncan be used as a guide to attachment selection. .


INTRACORONAL ATTACHMENTS

Intracoronal precision attachment (Dr. Herman E.S Chayes)

Precision attachment (prefabricated type)

Semiprecision attachments (custom made)

Conventional attachment T shaped attachments

Modern attachment H shaped

attachments

Contact plate

Adjustment slot

Tube Head

Reinforcing plate


Beyeler attachment :Beyeler attachment : Active friction grip attachments :Active friction grip attachments : In many ways these resemble passive attachments, In many ways these resemble passive attachments,

but as they are used in situations where the but as they are used in situations where the articulation needs to be separated repeatedly eg. articulation needs to be separated repeatedly eg. Removable bridgework they include a spring, usually Removable bridgework they include a spring, usually a split patrix design.a split patrix design.

Used in anterior and premolar regions. Used in anterior and premolar regions.


MECHANICS OF RETENTION

Frictional : Preiskel group I

Retention – Surface area contact

Function of the length – Controlled by height of clinical crown

– Intermaxillary space available

Function of cross sectional dimensions

Mechanical : Preiskel group II

Auxillary mechanical retentive features

Ex. Spring loaded plunger / clips www.indiandentalacademy.comwww.indiandentalacademy.com

Passive Attachment : Patrix and Matrix inter lock in a jigsaw fashion..Retention depends on shape of the joint, area of contact and accuracy of fit Channels of passive attachment may be round / elliptical slides

DEPENDING ON ARTICULAR RETENTION

Passive attachment Active attachment Locked precision attachment

Omega Beyelerwww.indiandentalacademy.comwww.indiandentalacademy.com

ACTIVE ATTACHMENT Active friction grip attachment Active snap grip attachments

McCollum Crismani Crismani

Mc.Collum active friction grip – used in posterior areas and available sizes 4mm and 5.5. mm

Crismani active friction grip – available size range 3mm to 7mm used in anterior and premolar areas


Mc Collum attachment :

H shaped attachment

Single adjustment slot

An H shaped attachment indicated for fixed movable bridgework, removable partial dentures and distal extension partial dentures when cross arch stabilized.


Stern attachment

Two adjustment slots

H shaped configuration. This attachment is an intra-coronal, active friction grip

attachment to which a distal hinge block has been added. Used as a stress breaker attachment and in fixed removal

bridge work and RPDs.


Crismani attachment :

Available as Rigid / Resilient

Rigid crismani attachment

Frictional grip

Mechanical grip

These come in resilient and rigid forms. The rigid types are available with both friction and mechanical spring clip retention mechanisms. They come in intracoronal active friction grip aswell as snap grip varieties. The hinged, resilient type attachment can be used in distal extension cases.


This resilient attachment can be used as a vertical This resilient attachment can be used as a vertical stress breaker, as a hinged stress breaker, or a stress breaker, as a hinged stress breaker, or a combination of both.combination of both.

Two types of resilient crismani attachments are Two types of resilient crismani attachments are

available, one allowing a pure hinge movement available, one allowing a pure hinge movement and the other allowing lateral movement in and the other allowing lateral movement in combination with hinge movement. combination with hinge movement.


Ney’s attachment :

Latch retained

Conventional H shaped

Ney loc split lingual


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


Bakers attachment

Schatzmann attachment

These are intraconal nonresilient attachments. They come in anterior, bicuspid and molar sizes.

H shaped configuration. This attachment is an intra-coronal, active friction grip attachment to which a distal hinge block has been added.

Used as a stress breaker attachment and in fixed removal bridge work and RPDs.


Semiprecision attachments

Defined as rigid metalic extension (patrix) of a fixed or removable dental prosthesis that fits into a slot type key way (matrix) in a cast restoration allowing some movement between the component”.

- GPT8

Gillete (1923) : The first semiprecision attachment

Zinner (1979)

Locking semiprecision attachment

Non locking semiprecision attachment


Louis blatter fein (1969) : Four rest seat preparation

Occlusal form / outline form – controls amount of rotation

Circular Dove tail Rectangular Mortice

(Rigid – locking type) Resilient Some resiliency (Non-locking type)

Proximal form / side walls – lateral force control

Parallel outline Tapering outline The angle of the proximal wall with the gingival floorwww.indiandentalacademy.comwww.indiandentalacademy.com

Gingival floor form : serves the function of reciprocation

Flat Inclined Channeled

Added reciprocation

Mortice occlusal form

Rectangular occlusal form


Advantages :

Applied in clinical situations – employing various rest seat outline forms.

Variation in tooth size and shapes are easily accommodated.

Better crown contour compared to prefabricated type

Disadvantages :

Long term wear is more – softness of alloy used.

No standardization of sizing : Lack of interchangiability of male and female attachment.

Greater degree of laboratory skill and attention in detail. www.indiandentalacademy.comwww.indiandentalacademy.com

EXTRACORONAL ATTACHMENTS

Introduced by Henry R. Boos (1900)

Modified by F Ewing Roach (1908)

Application

Kennedy’s class I and class II

Boitel (1978)

Rigid attachments

Resilient attachments

Bar attachments www.indiandentalacademy.comwww.indiandentalacademy.com

EXTRACORONAL ATTACHMENT

Rigid attachments Hinged attachments (Stress breaking action)

Resilient attachments

ERA

O-ring

Advantages :

• No alteration of contour of the abutment crown

• Can be used in short abutment teeth

• Greater freedom in the design

• Ease of insertion and removal www.indiandentalacademy.comwww.indiandentalacademy.com

Disadvantages (Wolf RE 1980) :

Lack of occlusal stability

Bulky

Rebasing problems

Improper control of force distribution

Encroachment on the gingival papilla – use of mini attachment


RIGID EXTRACORONAL ATTACHMENTS

Roach attachment (ball and tube attachment)

Oldest attachment

Patrix – round ball

Matrix - tube

Pin and tube attachment

The simplest

Patrix - pin

Matrix – tube www.indiandentalacademy.comwww.indiandentalacademy.com

Stabilex attachment

Two retention pins

Disadvantage is increased length Matrix Patrix

Assembled

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


Conex attachmentConex attachment

Sides provides precise path of insertion that resist rotational forces. Pins act two types: Providing frictional retention, mechanical lock.

Modified Conex : Enables operator to screw the removable section of prosthesis in place. Application tooth supported prosthesis where adequate plaque control is possible, unilateral distal extension spaces, small restorations for bounded spaces. Bracing arms not required because of the generous lateral surface area of the attachment. www.indiandentalacademy.comwww.indiandentalacademy.com

RESILIENT EXTRA CORONAL ATTACHMENT

•Dalbo / Dallabona attachment

a) Patrix

b) Matrix

These are known as Dalla bona slide block or Dalbo stud anchor. They are simple attachments available in non-resilient, resilient and stress broken types.

They are useful when there is minimal vertical space available and rotation, reesilience and retention are desired.


The attachment consists of a single piece The attachment consists of a single piece male stud soldered to the coping and a single unit male stud soldered to the coping and a single unit female processed within the denture. female processed within the denture.

Types : Types : Rigid cylindrical dolla bonaRigid cylindrical dolla bonaSpherical variety (resilient) Spherical variety (resilient) Stress broken Stress broken

The stress broken version is similar to the The stress broken version is similar to the resilient with exception that female housing is resilient with exception that female housing is longer and incorporates a coil spring.longer and incorporates a coil spring.


Ceka attachment

Was developed by Karl Cluytens, 1951 and improved in 1968

Two types - Ceka NV attachment

- Ceka revax. Used as a direct retainer in partial dentures and overdentures

Is rigid and also non rigid category of extracoronal attachments. According to Waltz 1973 does not seem to have any adverse effect on health of abutment teeth and surrounding tissues.


ROLE OF ATTACHMENTS AS STRESS BREAKER

Rigid system Non-rigid system Stress breaker

Broken stress philosophy

Mensor stress can only be selected, altered or blocked

“Stress director” www.indiandentalacademy.comwww.indiandentalacademy.com

ASC-52 attachment

STRESS BREAKER DESIGNS

This is an example of an extracoronal resilient attachment that posses universal resilience.

It consists of an extracoronal slide attachment with a spring activated universal hinge joint and adjustable retention. It is the smallest stress director in dentistry and is used for distal extension RPD’s.


Neys distal extension stress breaker

Ney attachments are intracoronal snap grip attachments.

Available in 2 basic designs, the familiar chayes with adjustable wings and the neyloc design with gingival retention feature.


Stern stress breaker

H shaped configuration. attachment is an intra-coronal, active friction grip attachment to which a distal hinge block has been added.

Used as a stress broken attachment and in fixed removal bridge work and RPDs.


Extracoronal resilient attachment (ERA) :

(ERA)

Colour coded retention caps Most flexible White > Orange > Blue > Gray Most rigid

Two types of ERA

Standard

Reduce vertical (ERA – RV) – male part is 0.5mm shorterwww.indiandentalacademy.comwww.indiandentalacademy.com

Matrix Patrix

Use of ERA in DEB cases

Use in over denture

Yen Chen Ku et al (2000) : ERA provides esthetics, vertical resiliency, easy replacement of worn dentures

Vertical resiliency of 0.4mm

Universal joint hinge action


O-ring attachment

Patrix - post with the groove or undercut.

Matrix – O-ring synthetic polymer gaskets

O-ring are made up of Silicone Nitrile Fluorocarbon Ethylene propylene


Advantages of O-ring

Ease in changing the attachment

Wide range of movement

Low cost

Different degrees of retention

Elimination of the time / cost of the superstructure


STUD ATTACHMENTS (ANCHORS) “Anchor the roots” Simplest of all the attachment

Partrix – dowel / post retained restoration

Matrix – denture base of the prosthesis

Classified as :

Rigid stud unit

Resilient stud unit

Extraradicular units

Intraradicular units

Extraradicular Intraradicular www.indiandentalacademy.comwww.indiandentalacademy.com

Space requirement of these attachment is intermediate between dome shaped coping and thimble shaped coping.

These should be placed parallel to the long axis of the tooth.


DALBO STUD ATTACHMENT

Rigid unit

Ball and socket unit

(Vertical and rotational movement)

Retention


ROTHERMAN ECCENTRIC ATTACHMENT

It is one of the smallest of stud attachments and hence requires very little space (average bt. 1.6mm). It is available in nonresilient and resilient versions. Simple to use with adequate retention and ease of

maintenance.

Disadvantages : Chair –side insertion of keyway is difficult.


ZEST ANCHOR ATTACHMENT

Zest anchor is a stud attachment it consists of a metallic funnel shaped tube that is cemented into the root canal of the tooth and a polyethylene stud that is attached to the denture base.

The head of the stud squeezes past the construction in the neck of the funnel to retain the denture on the tooth. It derives its retention from within the tooth


GERBER ATTACHMENT

This is one of the largest of the stud units.

Provides good retention stability has adjustable springs and it is readily replaceable.

Disadvantages : Complex attachment systemRequres more spaceMaintenance problemsIt permits very little rotational action to

torquing of abutment teeth occurs with alveolar resorption .


SCHUBIGER ATTACHMENT

Patrix : threaded post / screw

Matrix : recessed collar, cap nut / lock nut

Cut section


BAR ATTACHMENTS

Gilmore clip system (1913) - metal bar with retaining sleeve / clip.

Bar can be attached to the : Coping or crowns over the vital teeth

Post coping on endodontically treated teeth

Screwed down into the coping (implant system)

Types of bar attachments : Customised bar

Dolder bar

Ackermann’s bar

CM rider bar

Hader bar

Andrews bar www.indiandentalacademy.comwww.indiandentalacademy.com

Two groups of bar attachments : 1) Bar units - rigid2) Bar joints – permits rotation

Round / circular Oval / egg shaped

‘U’ shaped / parallel sided bars

Multiple sleeve bar jointsSingle sleeve bar joints

Depending on cross section

BAR JOINTS


DOLDER BAR

Egg shaped bar in cross section

Open sided sleeve

Two sizes 3.5mm x 1.6mm,

3.0mm x 2.2mm

Spacer – degree of movement


MOVEMENTS SEEN IN DOLDER BAR

Sagittal rotation Rest position Vertical translation

Implant supported over denture www.indiandentalacademy.comwww.indiandentalacademy.com

ACKERMANN BAR

Available in different cross section

Circular cross section – can be bent in all planes

A short extension of 5mm is carried behind the most distal root and the sleeve positioned on this section prevents tendency for distal part to rise when sticky foods are chewed. This is recommended where bar is set an antero-posteriro curve to prevent hinge rotation and motion.

Multiple sleeve bar joints are more versatile than single ones except bars that have slightly rigidity. www.indiandentalacademy.comwww.indiandentalacademy.com

CM BAR

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


HADERBAR

Helmut Hader in 1960

Available as a prefabricated plastic pattern

Prefabricated plastic pattern are adapted to master cast according to its contour and cast in alloy of choice . Sleeves of plastic have to be replaced for adjustments, hence metal sleeves can be substituted.


Clips with metal encapsulator

Advantage

Prefabricated plastic pattern – no need for soldering.

Precise fit, simplicity. www.indiandentalacademy.comwww.indiandentalacademy.com

Advantages of bar attachments : Rigidly splint the teeth Provides good retention, stability and support Provides cross arch stabilizationPositioned close to the alveolar bone (exhibit less leverage)

Disadvantages :

Bulk of bar Plaque accumulation Wearing Soldering procedure


MAGNETS AS ATTACHMENT

Since 1950 To retain maxillofacial prosthesis

Alu, Ni, Iron,Cobalt alloy (alnico)

Limited use – larger size

1960 “use of rare earth element” – High field strength – Can be used in smaller size.

Somarium cobalt (Sm-Co) (Joseph Becker Hoffer 1967)Neodymium iron boron (Nd-Fe-B) – 20% stronger Somarium iron nitride – High magnetization

Used for retention of mandibular overdentures (tooth and implant supported over dentures) www.indiandentalacademy.comwww.indiandentalacademy.com

Gilling’s magnetic attachment

(cobalt somarium alloy magnets)

“Split pole paired magnets”

Closed field magnetic system

Magnetic retainer with magnets

Magnetic keeper


Advantages of magnetic attachment :

Smaller size and strong attractive force

Produce constant force – constant retention

Easy to incorporate into the prosthesis

Automatic reseating

Boon for elderly patients (Parkinsonism, arthritic patient)

Less lateral force to the abutment tooth


Jackson magnetic attachment

(cobalt somarium alloy magnets)

Cemented in keeper Screwed in keeper


Disadvantages :

Loss of retention due to corrosion or heat instability

Requires encapsulation within inert alloys

Cannot be repaired

High cost

Limited force transmission - Magnets can slide on their keepers.


AUXILLARY ATTACHMENTS

Screw and tube attachment

Key and keyway / interlocks

Presso Matic or Isoclip

Bar connectors

Attachments for sectional dentures / bolts

Screw and tube attachment


Indications :

To overcome alignment problems

Connecting one restoration of fixed partial denture to another

Allowing the removal of long span fixed partial denture for repair and examination of abutment.


ATTACHMENT USED FOR SECTIONAL DENTURES

Two part dentures : One part - chrome cobalt base

Second part - removable acrylic flange with teeth

Advantage of superior esthetics and improved retention

Method of union :

Physical interference : Bolt retained prosthesis

Frictional resistance : Split post retained prosthesis


SECTIONAL DESIGNS

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


For critical analysis of these attachments, the need for For critical analysis of these attachments, the need for through knowledge of their principles and through knowledge of their principles and applications may be of help in obtaining a better applications may be of help in obtaining a better insight into their drawback and areas of potential insight into their drawback and areas of potential improvement.improvement.

The attachment-retainer removable partial denture The attachment-retainer removable partial denture presents a challenge in technical skill and presents a challenge in technical skill and understanding of the biomechanics of maxillo-understanding of the biomechanics of maxillo-mandibular function. mandibular function.

The main functions of the attachments are retention, The main functions of the attachments are retention, stress reduction and concealment for esthetic stress reduction and concealment for esthetic purposes. The attachment-retained removable partial purposes. The attachment-retained removable partial denture does attempt to return the patient to as near denture does attempt to return the patient to as near normal function and appearance as possible.normal function and appearance as possible.


Advanced removable partial dentures. James S. Brudvick Quint Int. Pub Pg. 115-152.

Contemporary fixed prosthodontics. Rosensteil, Third edition, Mosby Pub., pg. 543-566.

Overdenture made easy guide to implant and root supported prosthesis Harold W. Preiskel – George Zarb.

Precision attachments – a link to successful restorative treatment Gareth Jenkins Quint Publishing.

Theory and practice of precision attachment RPD – James L Baker Richard J Goodkins.


J Prosthet Dent 1973; 29(5): 494-497

J Prosthet Dent 1973; 29(2): 165-171.

J Prosthet Dent 1987; 58(3): 327-327.

DCNA 1970; 14(3): 595-601.

Quint Int 2000; 31(5): 311-317.

Quint Int 1987; 18(1): 4-51

J Prosthet Dent 2001; 86: 137-42

J Prosthet Dent 1981; 45(1): 37-43.

Int J Prosthet 1990; 3(1): 98-102.

Int J Prosthet 1990; 3(2): 165-173. www.indiandentalacademy.comwww.indiandentalacademy.com

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Precision attachments in prosthodontics/ orthodontics short term courses

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