The Laboratory Study of Resin-Bonded Fixed Partial Dentures in the Posterior Region (In Premolar-Sized Spans). Part 2. Mechanical Testing

Abstract

Background. To date, numerous retrospective studies on the use of resin-bonded fixed partial dentures (RBFPD) have proven their reliability. Nevertheless, there are still questions about the design of posterior resin-bonded fixed partial dentures for replacing 1 and 2 missing teeth.
 Objectives. The present research was an in vitro study of the fracture strength of resin-bonded fixed partial dentures (RBFPD) with movable connector on the heat-pressed ceramic minor retainer when replacing 1 or 2 missing premolars. 
 Methods. The laboratory research was carried out to study the fracture strength of fixed/movable RBFPD on acrylic moulds with a space equivalent to one or two premolars. The nature of RBFPD destruction and breaking loads in newtons were assessed by comparing the mean values according to the t-test. We studied 4 groups of RBFPD, depending on the type of retainer and the number of lost teeth.
 Results. The smallest fracture strength (1017.0 ± 49.0 N) was observed in the group with two missing teeth. In groups with 1mm thick occlusal rest, its deformation was observed. In the groups with 2 mm thick occlusal rest, partial fracture of the ceramic minor retainer was observed. Fixation loss of the adhesive wings or cast crowns as a large retainer was not observed. 
 Conclusions. Fixed/movable RBFPD replacing two missing premolars are less fracture resisted then when replacing one missing premolar. Fixation loss of the large retainers was not observed. Adhesive wings were as effective as cast crowns as a large retainer.