RESUMO
Objective@#To study the computational fluid dynamics (CFD) characteristics of ultrasonic root canal irrigation when the file was placed at a certain depth in the root canal, to provide a reference for clinical application.@*Methods @#First, scanning laser vibrometry (SLV) was utilized to analyze the characteristics of vibrational ultrasonic files under specific power. Then ICEM CFD 18.0 software was used to establish the root canal ultrasonic irrigation model. The insertion position of the ultrasonic working tip was set 1 mm away from the physiological apical foramen, and cloud images of the results were obtained by FLUENT 18.0 software. Volume fraction, flow velocity and pressure in the root canal were evaluated after setting the computing conditions.@*Results@#The vibration of the ultrasonic working tip was mainly transverse vibration with slight longitudinal vibration. The amplitude of transverse vibration of each part of the working tip was different. Maximum values were observed at the apical end area of the file, and the closer to the base of the file, the smaller the amplitude. The area where the cavitation volume fraction of the rinsing fluid was greater than 0 was concentrated around the working point. The flow rate of the irrigating fluid was up to 2 m/s, within the area 0.2 mm in front of the working tip, the velocity of the irrigating fluid was greater than 0.1 m/s, while within the area 0.8 mm from the root tip, the velocity of the irrigating fluid was small or even zero. The apical pressure value was non-positive when the tip of the file was 1 mm away from the apical foramen in this model.@*Conclusion@# Based on the experimental results, it appears that when the ultrasonic working tip was placed 1 mm short of the working length, the ultrasonic irrigating flow did not overflow the root apical foramen and the irrigation process was relatively safe; the irrigation fluid had a strong irrigation effect within approximately 0.2 mm in front of the working tip.
RESUMO
Objective:To investigate the clinical effect of ultrasonic root canal intermittent irrigation in endodontic vascular reconstruction.Methods:32 young permanent teeth with pulp and periapical lesions were randomly divided into two groups ( n=32): experimental group was treated with ultrasonic root canal intermittent irrigation and the control group was rinsed with sodium hypochlorite root canal. The changes of periapical lesions and root development were evaluated by preoperative and postoperative clinical symptom observation and radiograph examination, and the clinical effect of endodontic vascular reconstruction was discussed. The time of inflammation control was discussed by analyzing the starting point from the first diagnosis to the date of mineral trioxide aggregate (MTA) coverage. Results:The clinical symptoms of the 16 affected teeth in the experimental group and the control group disappeared, the periapical lesions were eliminated, and the root continued to develop. In the experimental group, root formation was observed in 13 of the affected teeth, with a success rate of 81.25% and a reduction rate of 18.75%. In the control group, root formation was observed in 10 of the affected teeth, with a success rate of 62.5% and a reduction rate of 37.5%. There was no difference in the effective rate between the experimental group and the control group ( P>0.05). The control time of inflammation was (28.44±5.98)days in the experimental group and (34.13±7.17)days in the control group, with statistically significant differences ( P<0.05). Conclusions:Ultrasonic root canal intermittent swabbing applied to pulp revascularization can achieve good clinical effect and shorten the time of inflammation control.