Análise fotoelástica da distribuição de tensões produzida na mandíbula pela simulação do esforço mastigatório em sobredentaduras muco-dento-suportadas e prótese total

Abstract

The aim of this study was to verify the distribution of masticatory efforts on jaws in overdentures and in a complete conventional denture. Three jaws of photoelastic material were made with double impression modelling technique from a edentulous human jaw. The molds were filled with photoelastic resin PLM-4 (Photolastic Inc., Raleigh, USA). A variation of root dispositions were made on jaws, separating them in three groups; Group I, without roots (control group); Group II, bilateral disposition of roots in the dental arch corresponding to two canines; Group III, one canine and a molar root disposed at the same hemi-arch in an unilateral situation. Conventional complete dentures and overdentures were made over these jaws that ocluded an acrilic cast fixed in a semi-adjustable articulator for the loading aplication (20 N). After "stress freezing", the models were cut off in their median line and analized on a transmission polariscope (Photolastic Inc., Raleigh, USA). Throughout the photoelastic frangent analysis it was concluded that: 1) all the photoelastic models (groups I, II and III) showed different patterns of stress distribution; 2) Group I showed a great concentration of stress all over the residual ridge; 3) Group II was the best in stress distribution when compared with the other groups. The high concentration of stress at the root apex decreased its concentration over all edentulous region of the arch; 4) In Group III a greater effort concentration was observed at the roots apex and also in the edentulous region.