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Dental Clasps

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					Clasping & Retention
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Survey lines Clasps Bracing Support Reciprocation Angle of approach Positioning

Survey Line

The survey line divides the tooth into Undercut and Non-Undercut areas

An alteration of the position of the survey line is produced by tilting the model and hence the tooth

Types of survey line
Medium Survey line Diagonal Survey Line

Low Survey Line

High Survey Line

Types of Clasp Relating to the Saddle & Survey line

Medium survey line with occlusally approaching clasp arm.

Diagonal survey line with gingivally Approaching clasp arm

Circumferential Clasp

Roach ‘T’ clasp

Types of Clasp

Diagonal survey line with occlusally Diagonal survey line with occlusally Approaching clasp arm Approaching clasp arm from the ‘C’ Clasp ‘FAR ZONE’

Circumferential Clasp

C. Clasp (Circumferential)
FULCRUM AXIS DISTAL MESIAL

SADDLE AREA

RETENTION

NEAR ZONE

BUCCAL

FAR ZONE

Direction of approach

Occlusal approach of the clasp arm Gingival approach of the clasp arm Into the undercut area Into the undercut area OCCLUSALLY APPROACHING CLASP GINGIVALLY APPROACHING CLASP

Functions of clasp components

Reciprocation

The direction of STRESS placed on a tooth by the RETENTIVE ARM Causing possible tooth displacement

x

√
The displacing force is Counteracted by a RECIPROCAL CLASP ARM

Bracing and Reciprocation

Tapered retentive arm (clasp) with the last third engaged in the undercut area

Reciprocal arm positioned above or on the survey line

Bracing and Reciprocation

‘C’ Clasp Circumferential Clasp Three Arm Clasp

Direction of stress transmitted by retentive arm (left) and displacing force Counteracted by reciprocal arm (right)

Circumferential (Ring) Clasp Occlusal View
BUCCAL BRACING BRACING

SUPPORT

BRACING

MESIAL DISTAL

SADDLE

RETENTION

LINGUAL

Circumferential (Ring) Clasp Buccal View
SUPPORT

MESIAL

BRACING

BRACING

DISTAL

SADDLE

Circumferential (Ring) Clasp Lingual View

MESIAL
BRACING

SADDLE DISTAL
RETENTION

Bounded Saddle Buccal View

For a bounded saddle the rest elements are inclusive

Free End Saddle

For a free end saddle the Occlusal rest is always at the opposite side of the abutment tooth

R.P.I. System Lingual View

R.P.I. System Occlusal view

R.P.I. System Buccal View

Any Questions


				
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posted:11/26/2009
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Description: use and descriptions of dental clasps