mouth preparation

Preparation of abutment teethم .احسان فارس التكايlecture no.2

EXTENDED OCCLUSAL REST

In Kennedy Class II, modification 1, and Kennedy Class III situations in which the most posterior abutment is a mesially tipped molar, This rest should extend more than one half the mesiodistal width of the tooth.

RPD totally tooth supported by means of cast retainers on all abutments

INTRACORONAL REST
Indicated only for tooth supported RPD
Advantages of internal rest seats:-
1- elimination of visible clasp
2- location of the rest seat in a more Favorable position in relation
to the tipping axis

Lingual Ball rest

Incisal Rests
Prepared in form of rounded notch at incisal angle of canine or incisal edge of incisor.
Should be approximately 2.5 mm wide and 1.5 mm deep.
Notch is beveled both labially and lingually.