Apical Micro-cracks Following Root Canal Preparation, Obturation, and Retreatment with Rotary and Reciprocating Instruments: An In-Vitro Study

Objectives: This study aims to evaluate apical cracks occurring after root canal preparation and retreatment using different NiTi rotary systems with either continuous rotation or reciprocating motion. Materials and Methods: A total of 40 freshly extracted single rooted teeth could were used in this study, teeth were divided into 2 main groups (n=20) for each. Group A was prepared with continuous rotation motion (Revo-S). Group B was prepared with reciprocation motion (Wave One). Both groups were divided into two subgroups. Subgroup I was retreated by continuous rotation motion (R-Endo). Subgroup II was retreated by reciprocation motion (Wave One. All teeth were trimmed 1 mm apically then scanned by digital stereomicroscope preparation, after root canal preparation, after obturation and after retreatment procedure. Chi-square test was used to compare between two groups in nonrelated samples Friedman test was used to compare between more than two groups in related samples. Wilcoxon test was used to compare between two groups in related samples. Results: No significant difference between continuous rotation motion and reciprocation motion in producing apical cracks during root canal preparation and retreatment procedure was found (p>0.05). Conclusion: Reciprocating motion resulted in a slightly higher number of apical cracks than continuous rotation, but the difference was not statistically significant.