Influence of Different Coronal Preflaring Protocols on Electronic Foramen Locators Precision

Abstract: The aim of this study was to evaluate the influence of different coronal preflaring protocols (absent, conservative and conventional) on the accuracy of Root ZX II, Raypex 6, and RomiApex A-15 electronic foramen locators (EFLs). Twenty mandibular molars with Vertucci’s type IV mesial roots were subjected to endodontic exploration and foraminal patency confirmation. Under 16x magnification, its real lengths (RL) were measured and registered (RL1). The canals were then irrigated with 2.5% sodium hypochlorite and electronically measured (EM1) employing the alginate model; all measurements were performed in triplicate by a blind operator using adjusted endodontic hand-files introduced until the apex foramen. Coronal preflaring procedures were sequentially performed with #25/.06 (conservative) and #25/.12 (conventional) instruments; new RLs extents were performed after each coronal preparation protocol (RL2/RL3), as same as electronic measurements (EM2/EM3). The devices error (mm) was evaluated considering the difference between RLs and EMs at each preparation stage; their precision was stablished adopting ±0.5 mm as tolerance margin. The EFLs error significantly reduced after conventional coronal preflaring protocol (p&lt;0.05), which not occur after the conservative one. The best precisions values were noted after conventional preparation as 90% (Root ZX II), 97.5% (Raypex 6), and 92.5% (RomiApex A-15). No significant differences were found in EFLs comparisons, regardless of the coronal protocol tested (p&gt;0.05). Under the conditions tested it can be concluded that the EFLs evaluated were precise. Moreover, the preflaring protocols influences its accuracy’s, where the less conservative one produced the best results.摘要：本研究旨在评估三种冠部预扩（coronal preflaring）方案（无预扩、保守型预扩与传统型预扩）对Root ZX II、Raypex 6及RomiApex A-15型电子根尖定位仪（electronic foramen locators, EFLs）测量精度的影响。选取20颗带有Vertucci IV型近中牙根的下颌磨牙，行根管探查与根尖孔通畅性确认。在16倍放大视野下测量并记录其真实长度（RL1）。随后用2.5%次氯酸钠冲洗根管，采用藻酸盐模型进行电子长度测量（EM1）；由一名盲法操作者使用校准后的牙髓手动根管锉，直至抵达根尖孔，每组测量重复三次。依次使用#25/.06（保守型）与#25/.12（传统型）器械完成冠部预扩操作；在每一步冠部预备后分别进行新的真实长度测量（RL2/RL3）与电子长度测量（EM2/EM3）。以各预备阶段中真实长度与电子测量值的差值评估各定位仪的测量误差（单位：mm）；将±0.5 mm作为容许误差范围，以此判定测量精度。传统型冠部预扩方案可显著降低各电子根尖定位仪的测量误差（p<0.05），而保守型预扩方案无此效果。传统型预备后各设备的最优精度分别为：Root ZX II达90%、Raypex 6达97.5%、RomiApex A-15达92.5%。无论采用何种冠部预扩方案，各电子根尖定位仪间的测量精度均无显著差异（p>0.05）。基于本试验条件可得出结论：所评估的三类电子根尖定位仪均具有良好精度；且冠部预扩方案会影响其测量精度，其中非保守型（传统型）预扩方案可获得最优测量效果。