RPD LAB CHAPTER 7 DIRECT RETAINER

1847

When was wrought wire circumferential clasp used?

DIrect retainers

THe components of a RPD that engage abutments and resist dislodging forces are called?

-INtracoronal direct retainer

-EXtracoronal direct retainer

2 types of direct retainers

Herman E.S. Chayes (1906)

WHo introduced teh frist intracoronal direct retainer

-Matrix

-Patrix

2 parts of a intracoronal direct retainer

Matrix

This intracoronal part is a metal receptable cotnained within the normal clinical contours of a fixed restoration

Patrix

This Intracoronal part is attached to the corresponding removable partial denture

1. SUprabuldge direct retainer

2. Infrabuldge direct retainer

2 Types of extracoronal direct retainer (clasp types)

Suprabuldge clasp

This type of clasp approaches the assocaited udnercut from an occlsual or incisla direction

1. Simple circlet cast circumferentual clasp assembly

2. Reverse circlet design

3. Mutliple circlet desing

4. Embrasure clasp design

5. RIng clasp design

6. C clasp design

7. Onlay clasp design

8. Wrought wire- circumferential clasp

8 types of surpabulge direct retainer

DR. N. B. NESBITT 1916

Who introduced simple circlet cast circumferential clasp assembly and year

SImple circlet cast circumferential clasp assembly

This clasp is remarkable for its simplcitity and ease of construction

Simple circlet cast circumferential clasp assembly

This clasp is consdiered the clasp fo choice for tooth supported RPD

Proximal surface of abutment adjacent to edentulous area

Origin of simple circlet cast circumferential clasp assembly

Reverse circlet desgin

THis clasp is often used when available undercut is located at facial or lingual line angle adjacent to an edentulous space

Multiple circlet design

This clasp involves two simple circlet clasps joined at the terminal aspects of their reciprocal elements

Multiple circlet design

This clasp is indicated when the pricipal abutment tooth is periodontally compromised and stresses originating from prosthesis retenttion can be favorably distributed between multiple abutment teeth

Embrasure clasp

THis clasp is essentually two simple circlets joined at their bodies

Embrasure clasp

THis clasp is most frequently used on the side of the arch where there is no edentulous space

mInor connector -> transverese the marginal ridges between the teeth

Where does the embrasure clasp arm originate from

RIng clasp design

THis clasp is most often indicated on a tipped mandibular molar

C clasp design

This clasp is also referred to as a "fish-hook" or "hairpin" clasp

C clasp design

This clasp is essentially a simple curclet clasp in which the retentive arm loops back to engage an undercut apical to the point of origin

Occlusal poriton of the retentive arm

IN C clasp design, This portion of the retentive arm is consdiered a minor connector and must be rigid.

Apical portion of the retentive arm

In C clasp design, This portion msut pass over the height of contour to engage the desired undercut

Onlay clasp design

This clasp design is idnicated when the occlsual surface of the abutment lies notecable apicalt to the occlusal plane.

Onlay clasp design

This serves as a vertical stop and also aids in the establishment of an acceptable occlusal plane

Dr. F. EWing Roach 1913

Who indtroduced the dobule bow clasp and year

Dr. O. C. Applegate

Who introduced the modified wrought wire clasp assembly known as the combination clasp

1.Occlusal rest

2.Cast metal reciprocal arm

3. Wrought wire retentive arm

3 Components of a combination clasp

Dr. F. Ewing 1930

Who introduced the bar type or roach clasp and year

-T clasp design

-Modified T clasp design

-Y clasp design

3 Types of infrabuldge direct retainer

T-clasp design

THis clasp design derives its name from the shape created where the retentive clasp arm joins the vertical aspect of the approach arm

Kennedy class I & II

For T clasp design, what kennedy class is it used for?

Modified T-clasp design

THis infrabulge clasp design, is essentially a t clasp that lacks the nonretentive horizontal projection

True

True or false: modified T clasp can be used in kennedy class I & II

Y clasp design

THis infrabuldge clasp design is formed when the appriach arm terminates in the cervical third of the abutment, while the mesial and distal proejctions are positioned near the occlusal/incisal surface

1. Rigid clasp shoulder (S)

2. Midsection of the clasp arm (M)

3. Flexible clasp TErminus (T)

3 distinct segments of suprabuldge retentive clasp arm

Rigid clasp Shoulder (S)

THis clasp segment originates from the minor connector and proejcts across the axial surface of the abutment

Midsection of the clasp arm (M)

THis clasp segment continues along the abutment surface and approaches the height of contour

Flexible clasp Terminus (T)

This clasp segment crosses apical to the height of contour, contact in the abutment on a surface udnercut relative to the path of prosthesis insertion and removal

Indirect retainer

The framework component that resists rotational displacement of an extension base away from the supporting tissues is called?

1. Auxillary occlusal rest

2. Cingulum rest

3. Incisal rest

3 forms of indriect retainer

Auxillary occlusal rest

This type of indreict retainer is the preferred component for indirect retention. Because of its lcoation and orientation, an occlsual rest permits forces to be directed within the long axis of the corresponding abutment

CIngulum rest

This type of indirect retainer generally limited to maxillary. The normal morphology of this tooth lends itself to appropriate rest seat preparation with minimal recontouring

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