Fracture resistance exhibited by endodontically treated and retreated teeth shaped by ProTaper NEXT versus WaveOne: An in vitro study

AIM: To compare the fracture resistance exhibited by teeth after primary endodontic treatment and retreatment. MATERIALS AND METHODS: One hundred freshly extracted human teeth were selected. 20 samples served as control (untreated). Eighty experimental samples were divided into two groups (n = 40) for instrumentation using rotary Protaper NEXT (PTN) or reciprocating WaveOne (WO) files and obturated using warm lateral compaction. Half of the samples (n = 20) from each group were subjected to a load. The remaining half were subjected to retreatment using Protaper universal retreatment files (RFs) followed by a file larger than the master apical file used in groups 1 and 2 and reobturated. Group A: Control, Group B: PTN + obturation, Group C: WO + obturation, Group D: RF + PTN + obturation and Group E: RF + WO + obturation. The retreatment specimens were also subjected to load and the readings acquired were statistically analyzed. RESULT: When compared between the groups, control group exhibited the highest fracture resistance (P < 0.01). When multiple tests were performed, Group E exhibited significantly less fracture resistance (P < 0.01). CONCLUSION: Endodontic treatment and retreatment both results in lowering the fracture resistance of a tooth.