Cone-beam computed tomographic evaluation of remaining dentin thickness in bifurcated roots of maxillary first premolars after rotary instrumentation and post space preparation: An in vitro study

Background Intraradicular procedures remove radicular dentin and jeopardizing longevity of a tooth. Traditional in vitro methods used to determine the remaining dentin thickness (RDT) have limitations. Aim The aim is to evaluate, using cone-beam computed tomography (CBCT), RDT following rotary instrumentation and post space preparation in buccal and palatal roots of maxillary first premolars. Materials and Methods Twenty-three maxillary first premolars with two roots were selected. CBCT images were taken preoperatively, after instrumentation and Parapost 3 and 4 preparation (CBCT 1, 2, 3, and 4). RDT was measured 5 mm above apex, 1 mm below furcation, and 1 mm above furcation (Levels 1, 2, and 3). Data were analyzed using ANOVA and post hoc Tukey's test (P = 0.05). Results Rotary instrumentation and post space preparation reduced RDT in all walls of buccal and palatal roots. Post space preparation with Parapost 3 and 4 reduced RDT in the palatal wall of buccal root to <1 mm and Parapost 4 reduced all walls to 1 mm of dentin. Conclusion Post space preparation in maxillary first premolars should be performed cautiously. It is safer to place a post in the palatal root of this tooth and limit preparation to Parapost 3.