Objective: This in-vitro studycompared the effect of casted versusflexible removable partial denture(RPD) designs on the stresses transmitted to the supporting structures of unilateral distal extension base with two modification spaces.
Materials and Methods:Twelve identical partially edentulous mandibular resin model of unilateral distal extension ridge were used for this study. Polyvinyl siloxane impression material was placed to simulate mucosa covering the ridge. After RPD framework was constructed. The models were classified into two equal groups according to the processing of denture base. These includes: - Group < /strong> (I) casted mandibular distal extension RPD. Group < /strong> (II) flexible base mandibular distal extension RPD .On the model and after the strain gauges were luted to root surface of abutment teeth, unilateral load of 100N was applied on central fossa of 2nd premolar tooth on both sides ,right canine ,right 2nd molar and left ridge. The strain subjected to root surface of abutments was recorded by Lloyed testing machine.
Results:1) Abutment distal surface of loaded and unloaded side subjected to high amount of strain for casted distal extension removable partial denture. 2) The lingual surface of abutment teeth subjected to high amount of strain followed the distal surface for resilient denture RPD in both loaded & unloaded side. 3) Abutment root surface of loaded side for both casted & flexible base RPD subjected to more strain compared to unloaded side. 4) casted RPD exhibit less strain subjected to abutment surface of load side compared to flexible base one..
Conclusions:1) From tissue preservation point of view, casted distal extension removable partial denture is a prosthetic approach to minimize stress applied to the abutment teeth.2)casted distal extension RPD is superior to flexible base in regard to stress transmitted to abutment teeth.