THE LABORATORY STUDY OF RESIN-BONDED FIXED PARTIAL DENTURES IN THE POSTERIOR REGION (IN PREMOLAR-SIZED SPANS). PART 1

Background. Developed at the end of the 20th century, resin-bonded fixed partial dentures are now a real alternative to traditional bridges and intraosseous implants. The mean survival rate of conventional fixed partial dentures clearly exceeds the mean survival rate of adhesive fixed partial dentures. Debonding of fixed/fixed resin-bonded fixed partial dentures is associated with the difference in the natural mobility of the abutment teeth. Therefore, the fixed/movable resin-bonded fixed partial dentures are preferable. Objectives — to study the stress distribution in fixed/movable resin-bonded fixed partial dentures RBFPD using finite element analysis. Methods. The finite element method was used to preliminary estimate the stress distribution pattern in fixed/movable resin-bonded fixed partial dentures (metal or fiberglass-composite). The calculation was carried out using special programs (Ansys 12.2 Inc. Ansys — USA and AWP 3 D Studio — Russia). Results. The medial area of stresses is located only in the contact zone of the occlusal rest in the quantitative range of 32-60 N/mm2. The distal area of stresses corresponds to the distal connector, being approximately in the same range — 40-65 N/mm2. In the case of a metal retainer, the stresses also apply to it — 4-37 N/mm2. In the case of a fiber-composite retainer, stresses are practically not applied to it — 1-14 N/mm2. Conclusions. Analysis of the stress distribution pattern for the fixed/movable resin-bonded fixed partial dentures, obtained by the finite element method, confirmed: 1) the expediency of shortening the minor retainer 2) the choice of a rigid metal (possibly ceramic) major retainer instead of a weakly rigid fiber-composite major retainer.