Evaluation of dentinal microcrack formation during endodontic microsurgery: a micro-CT evaluation of piezoelectric root resection and root-end preparations with ultrasonic tips

OBJECTIVES: Dentinal microcracks are frequently observed during endodontic microsurgery and are often considered unavoidable. Despite advances in surgical instrumentation, the influence of these technologies on microcrack formation remains unclear. Therefore, this study aimed to evaluate the prevalence and potential propagation of dentinal microcracks associated with piezoelectric root resection and zirconium nitride-coated ultrasonic root-end preparation. METHODS: Sixty extracted human maxillary incisors were randomly allocated into four groups (n = 15). Root resection was performed using either a Lindemann bur or a piezoelectric instrument, followed by root-end preparation with either a diamond-coated or zirconium nitride-coated ultrasonic tip. Micro-computed tomography scans were obtained preoperatively, after root resection, and following root-end preparation. Two calibrated examiners independently assessed microcrack number and type and recorded procedural time. Statistical analysis included Bonferroni-adjusted pairwise comparisons and chi-square testing. RESULTS: No statistically significant differences were found among groups in microcrack frequency (p = 0.783) or microcrack type (p = 0.407), and all detected microcracks were present preoperatively. Mean resection time was 10.8 s with the Lindemann bur and 67.09 s with the piezoelectric insert. Mean preparation time was 68.27 s using the diamond-coated tip and 15.83 s using the zirconium nitride-coated tip. CONCLUSIONS: Piezoelectric instruments and zirconium nitride-coated ultrasonic tips did not significantly influence dentinal microcrack formation or propagation compared with conventional techniques, although notable differences in procedural efficiency were observed. CLINICAL SIGNIFICANCE: This study highlights how contemporary endodontic microsurgical techniques influence both dentinal integrity and procedural efficiency. While some approaches may require additional operative time, they may also offer advantages in surgical control and visualization.