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以及最终根管充填的影响。将工作长度精准控制至根尖狭窄部（通常较解剖根尖短0.5~1 mm）至关重要。为更精准地测定工作长度，临床常采用电子根尖定位仪（electronic apex locators）。目前市场上共有六代电子根尖定位仪，但针对不同根尖定位仪搭配适宜冲洗液以精准测定工作长度的相关研究仍不够充分。本研究对120颗新鲜拔除的人类单根牙的实际工作长度进行测量，并分别采用第三代（Root ZX）与第六代（Raypex 6）电子根尖定位仪，在干燥介质、5.25%次氯酸钠溶液、2%氯己定溶液三种环境下，分别在未行冠方预扩与冠方预扩后的状态下测定其工作长度，随后将两种仪器的测定结果与实际工作长度进行对比。研究收集所有数据并制表，随后采用单因素方差分析（one-way ANOVA）结合事后检验，评估实际工作长度、Root ZX与Raypex 6定位仪测得的工作长度的平均准确性之间的显著差异。结果显示，采用Raypex 6定位仪在干燥介质中对经冠方预扩的牙根进行工作长度测定时，所得结果的准确性最为突出；而采用Root ZX定位仪时，经冠方预扩并使用氯己定冲洗液的牙根，其测得的工作长度准确性最高。