Should adhesive debonding be simulated for intra-radicular post stress analyses?

Abstract

ObjectiveElucidate the influence of debonding on stress distribution and maximum stresses for intra-radicular restorations. MethodsFive intra-radicular restorations were analyzed by finite element analysis (FEA): MP=metallic cast post core; GP=glass fiber post core; PP=pre-fabricated metallic post core; RE=resin endocrowns; CE=single piece ceramic endocrown. Two cervical preparations were considered: no ferule (f0) and 2mm ferule (f1). The simulation was conducted in three steps: (1) intact bonds at all contacts; (2) bond failure between crown and tooth; (3) bond failure among tooth, post and crown interfaces. Contact friction and separation between interfaces was modeled where bond failure occurred. Mohr–Coulomb stress ratios (σMC ratio) and fatigue safety factors (SF) for dentin structure were compared with published strength values, fatigue life, and fracture patterns of teeth with intra-radicular restorations. ResultsThe σMC ratio showed no differences among models at first step. The second step increased σMC ratio at the ferule compared to step 1. At the third step, the σMC ratio and SF for f0 models were highly influenced by post material. CE and RE models had the highest values for σMC ratio and lower SF. MP had the lowest σMC ratio and higher SF. The f1 models showed no relevant differences among them at the third step. SignificanceFEA most closely predicted failure performance of intra-radicular posts when frictional contact was modeled. Results of analyses where all interfaces are assumed to be perfectly bonded should be considered with caution.