The Effect of Coronal Pre-flaring and Root Canal Irrigant on Apex Locators Accuracy: In-Vitro Study.

Successful root canal treatment is influenced by the apical extent of root canal preparation and the eventual root canal filling. Achieving the full working length until the apical constriction which is usually 0.5 – 1 mm shorter than the anatomical apex is crucial. Electronic apex locators were used to detect the working length more accurately. There are six generations of electronic apex locators in the market. The selection of the appropriate irrigation with each apex locator for accurate working length determination is not fully investigated. The actual working lengths of 120 freshly extracted human single-rooted teethTh were measured and compared with their working lengths using 3rd generation (Root ZX) followed by 6th generation (Raypex 6) apex locators in dry medium, presence of 5.25% sodium hypochlorite, and 2% chlorhexidine, without coronal pre-flaring and after coronal pre-flaring using the same irrigating media. Data were collected, tabulated and afterwards analysed using one-way ANOVA with post-hoc to evaluate the significant difference in average WL between actual WL, Root ZX, and Raypex 6 apex locator working length accuracy. Results revealed that the significant results were shown in roots that were coronally pre-flared and their working lengths were measured in a dry medium using Raypex 6 apex locator. While using the Root ZX apex locator, the most accurate results were shown in roots that were coronally pre-flared and their working lengths were measured while using chlorhexidine irrigating solution.

成功的根管治疗效果受根管预备的根尖段范围与最终根管充填质量的共同影响。将工作长度（working length, WL）精准控制至根尖狭窄部（通常较解剖根尖短0.5~1mm），是根管治疗成功的核心环节。电子根尖定位仪（electronic apex locators）可显著提升工作长度的测定精度，目前市场上该类设备已迭代至六代。目前尚未完全明确适配各类电子根尖定位仪的最优冲洗方案以保障工作长度测定的精准性，相关研究仍有待深入。本研究纳入120颗新鲜拔除的人单根牙，分别在未行冠方预扩、冠方预扩两种状态下，以干燥介质、5.25%次氯酸钠溶液及2%氯己定溶液为冲洗介质，采用第三代（Root ZX）与第六代（Raypex 6）电子根尖定位仪测定其工作长度，并与实际工作长度进行对比。研究收集所有数据并完成制表，随后采用单因素方差分析（one-way ANOVA）结合事后检验，对比实际工作长度与Root ZX、Raypex 6电子根尖定位仪测得的工作长度之间的平均精度差异。研究结果显示：在已行冠方预扩的患牙中，采用Raypex 6电子根尖定位仪并以干燥介质为测试环境测定工作长度时，测定结果与实际值间存在统计学显著差异；而采用Root ZX电子根尖定位仪时，在已行冠方预扩且以氯己定溶液为冲洗介质的条件下，其测定结果精度最高。