Restorative and Prosthetic Dental Sciences, College of Dentistry, King Saud bin Abdulaziz University for Health Sciences, National Guard Health Affairs, P.O. Box 22490, Riyadh, 11426, Saudi Arabia.
King Abdullah International Medical Research Centre, National Guard Health Affairs, Riyadh, Saudi Arabia.
Clin Oral Investig. 2021 Jun;25(6):4137-4143. doi: 10.1007/s00784-020-03745-z. Epub 2021 Jan 6.
To assess the effect of additional apical enlargement using nickel titanium (NiTi) instruments on the incidence of microcracks using micro-computed tomographic analysis.
Fifty-one premolars with single canals were enlarged to ProTaper Gold (PTG) F2 (25/08) (Dentsply Sirona), ProFile Vortex Blue (VB) 25/06 (Dentsply Tulsa), or WaveOne Gold (WOG) primary (25/07) (Dentsply Sirona) NiTi rotary instruments (n = 17 each). Afterward, additional apical enlargement was performed in each group with its corresponding larger instrument (F3 (30/09), VB 30/06, or WOG Medium (35/06) instruments, respectively). All teeth were imaged with micro-computed tomography before canal enlargement and after initial and additional apical enlargements to detect new microcracks at the apical 5 mm. An Aligned Rank Transform ANOVA was conducted to examine the effects of file type and canal enlargement on the number of new microcracks resulting from enlargement. A Kruskal-Wallis test was run to compare the file types at each canal enlargement stage.
A significant main effect (P = 0.026) of canal enlargement on the number of new microcracks was found; the number of apical microcracks found after additional enlargement was significantly greater than baseline (P = 0.021); no significant difference was found between baseline and initial enlargement (P = 0.506) and between initial enlargement and additional enlargement (P = 0.252). The Kruskal-Wallis tests found no difference between file types at baseline (P = 0.348), after initial enlargement (P = 0.369) or additional enlargement (P = 0.133).
Regardless of the instrumentation system used, additional apical enlargement led to the formation of high number of new microcracks.
The results indicated that additional enlargement induced significant number of apical microcracks.
使用微计算机断层扫描分析评估使用镍钛（NiTi）器械进行额外根尖扩大对微裂纹发生率的影响。
51 颗单根管前磨牙分别用 Protaper Gold（PTG）F2（25/08）（登士柏西诺德）、ProFile Vortex Blue（VB）25/06（登士柏图拉）或 WaveOne Gold（WOG）初级（25/07）（登士柏西诺德）NiTi 机用器械扩大至 F2（25/08）（Dentsply Sirona）、ProFile Vortex Blue（VB）25/06（Dentsply Tulsa）或 WaveOne Gold（WOG）初级（25/07）（Dentsply Sirona）NiTi 旋转器械（每组 17 个）。然后，在每组中使用相应的较大器械（F3（30/09）、VB 30/06 或 WOG 中号（35/06）器械）进行额外的根尖扩大。所有牙齿在根管扩大前、初始扩大后和额外扩大后均用微计算机断层扫描成像，以检测根尖 5mm 处的新微裂纹。采用秩和检验方差分析（ANOVA）比较文件类型和根管扩大对因扩大而产生的新微裂纹数量的影响。采用 Kruskal-Wallis 检验比较每个根管扩大阶段的文件类型。
发现根管扩大对新微裂纹数量有显著的主要影响（P=0.026）；额外扩大后发现的根尖微裂纹数量明显多于基线（P=0.021）；基线与初始扩大之间（P=0.506）和初始扩大与额外扩大之间（P=0.252）无显著差异。Kruskal-Wallis 检验发现基线时（P=0.348）、初始扩大后（P=0.369）和额外扩大后（P=0.133）文件类型之间无差异。
无论使用何种仪器系统，额外的根尖扩大都会导致大量新微裂纹的形成。
结果表明，额外扩大诱导了大量的根尖微裂纹。
