Abstract: Objective    To evaluate the effectiveness of 4 irrigation methods in cleaning the isthmus resin teeth of 3D printing and to optimize the irrigation time. Methods    The study was conducted in the laboratory of the Stomatology Center of Shenzhen People′s Hospital from November 2021 to June 2022. Totally 80 standardized instrumented mandibular resin teeth with same isthmus were divided into 4 groups of 20 teeth each by simple random sampling，and were recorded as the lateral needle irrigation group（irrigation using a conventional lateral syringe needle），the ultrasonic group ［irrigation using the ultrasonically activated irrigation （UAI）system］，the EDDY sonic group（irrigation using the EDDY sonic activation system），and the PIPS laser group ［irrigation using the photon-initiated photoacoustic streaming（PIPS）laser］. The 4 groups of resin teeth were subjected to terminal irrigation（single irrigation time of 20 s）according to grouping，and then the remaining length of the contents of the isthmus and the penetration length of the irrigant were measured and compared. Then 60 instrumented resin teeth with the same isthmus were randomly divided into 3 groups of 20 teeth each，which were recorded as 5 s group，10 s group，and 30 s group according to the single irrigation time，then the one with the optimal measurements of the remaining length of the isthmus contents and the penetration length of the irrigants was selected for irrigation，and the isthmus cleaning effectiveness indexes were compared for each irrigation time group. Results    The differences in the total comparison of the remaining length of the contents in the isthmus and the penetration length of the irrigant of each irrigation method group were statistically significant（F values of 20.470 and 16.571，respectively，P < 0.001）；among them，the remaining length of the contents in the isthmus of the EDDY sonic group and the PIPS laser group was less than that of the lateral needle irrigation group and the ultrasonic group，and the length of the penetration of the irrigant was more than that of the lateral needle irrigation group and the ultrasonic group；the results of these two indicators of the clearing effect of the EDDY sonic group were also better than those of the PIPS laser group；the differences were statistically significant（all P < 0.05）. Comparing the isthmus cleaning effect of each irrigation time group irrigated with the EDDY sonic activation system，the difference was statistically significant only for the remaining length of contents（F = 13.441，P < 0.001）. Among them，the remaining length of the contents in the isthmus in the EDDY sonic group（single irrigation time of 20 s）was significantly less than that in the 5 s，10 s，and 30 s groups，the remaining length of the contents in the 30 s group was less than that in the 5 s group，and the differences were statistically significant（all P < 0.05）；the difference was not statistically significant in comparison among the other irrigation time groups（P > 0.05）. Conclusion    Three supplementary irrigation methods are better than lateral needle irrigation，with the EDDY sonic activation system being better in cleaning the isthmus，and the best cleaning effect is achieved when the single irrigation time is 20 s.

Key words: root canal therapy；isthmus；ultrasonically activated irrigation, UAI；EDDY sonic；photon-initiated photoacoustic streaming, PIPS；laser

摘要： 目的    比较4种根管冲洗方法对3D打印树脂牙管间峡区的清理效果，并优化冲洗时间参数。方法    研究于2021年11月至2022年6月在深圳市人民医院口腔医学中心实验室进行。选取80颗预备后的具有相同管间峡区的3D打印树脂牙经简单随机抽样分成4组，每组20颗，分别记为侧方冲洗组（使用传统的侧方注射器冲洗）、超声组［使用超声活化冲洗（ultrasonically activated irrigation，UAI）系统冲洗］、EDDY声波组（使用EDDY声波活化系统冲洗）、PIPS激光组［使用光子诱导光声流（photon-initiated photoacoustic streaming，PIPS）激光系统冲洗］。将4组树脂牙按照分组方式进行终末冲洗（单次冲洗时间为20 s）后，测量并比较管间峡区内容物剩余长度和冲洗液渗入长度。再选取60颗预备后的具有相同管间峡区的3D打印树脂牙随机分为3组，每组20颗，根据单次冲洗时间记为5 s组、10 s组和30 s组，选用管间峡区内容物剩余长度和冲洗液渗入长度测量结果最优的根管冲洗方法进行冲洗，并比较各冲洗时间组管间峡区清理效果指标。结果    各根管冲洗方法组管间峡区的内容物剩余长度、冲洗液渗入长度总的比较，差异均有统计学意义（F值分别为20.470、16.571，均P < 0.001）；其中，EDDY声波组、PIPS激光组管间峡区的内容物剩余长度小于侧方冲洗组和超声组，冲洗液渗入长度大于侧方冲洗组和超声组，且EDDY声波组的这两项清理效果指标结果还优于PIPS激光组，差异均有统计学意义（均P < 0.05）。使用EDDY声波活化系统冲洗的各冲洗时间组管间峡区清理效果比较，仅内容物剩余长度总的比较，差异有统计学意义（F = 13.441，P < 0.001）。其中，EDDY声波组（单次冲洗时间为20 s）管间峡区内容物剩余长度显著少于5 s组、10 s组和30 s组，30 s组内容物剩余长度小于5 s组，差异均有统计学意义（均P < 0.05）；其他各冲洗时间组间比较，差异无统计学意义（P > 0.05）。结论    3种新型辅助根管冲洗方法对管间峡区的清理效果均优于传统侧方注射器冲洗，其中以使用EDDY声波活化系统冲洗且单次冲洗时间为20 s时对管间峡区的清理效果较佳。

关键词: 根管治疗, 管间峡区, 超声活化冲洗, EDDY声波, 光子诱导光声流, 激光