Effect of Cavity Designs on Instrumentation, Obturation, and Fracture Resistance of Mandibular First Premolars With Vertucci V Canal.

INTRODUCTION: This study aimed to assess the effect of cavity designs on instrumentation, obturation and fracture resistance for mandibular first premolars with Vertucci V canal. METHODS: Mandibular first premolars with Vertucci V canal were scanned with microcomputed tomography. A total of 20 teeth with moderately curved canal were prepared with conservative endodontic cavity (CEC/M) or traditional endodontic cavity (TEC/M), and 30 with severely curved canal were prepared with CEC (CEC/S), modified CEC (MCEC/S) or TEC (TEC/S). CECs and MCEC were prepared using dynamic navigation systems. TECs were prepared freehand. Canals were prepared with WaveOne Gold, irrigated and then obturated with single-cone technique using iRoot SP sealer and WaveOne Gold gutta-percha cones. After restoration, all teeth were submitted to fracture resistance test. Removal of pericervical dentin, volume of dentin removal, area of untouched canal wall, accumulated hard tissue debris, centering ability, voids in canal filling, and load at fracture were evaluated. RESULTS: MCEC and CEC groups preserved more pericervical dentin above the alveolar bone level and more fracture resistance than TEC groups. At 3 mm from apical foramen, lower centering ability in mesiodistal direction was found in buccal canal of CEC/S group. More voids were found in the lingual canal for CEC/S compared with TEC/S (P < .05). CONCLUSIONS: CEC and MCEC prepared with dynamic navigation system could preserve more dentin above the alveolar bone and fracture resistance than TEC prepared freehand. For teeth with severely curved V canal, MCEC showed similar ability in instrumentation and obturation as TEC.