Tomoyuki Hongo, DDS, Satoshi Watanabe, DDS, PhD, Kanako Yao, DDS, PhD, Kazuhisa Satake, DDS, and Takashi Okiji, DDS, PhD
Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
Purpose: This study aimed to examine root canal irrigant activation using a computer-controlled hot tip (thermo-optically powered [TOP] tip) heated with a 980 nm diode laser system (Alta Modular Laser System), with regard to vaporized bubble formation and soft tissue dissolution capacity.
Materials and Methods: As a parameter of cleaning efficacy, the number and size of vaporized bubbles generated in root canal models during TOP tip-induced activation were analyzed with high-speed digital video imaging. To evaluate the soft tissue-dissolving efficacy of TOP tip-induced activation with a sodium hypochlorite irrigant, dissolution of porcine soft tissues filled in lateral canals set at two levels in root canal models were morphometrically analyzed. Irrigant temperature during TOP tip-induced activation was measured with thermocouples attached to the apical foramen and the lateral canals of root canal models.
Results: High-speed video imaging revealed that TOP tip-induced activation of the water that filled the root canal models, required less time to achieve the first bubble formation and generated a larger number of bubbles than a normal clear tip-induced activation using the same laser. NaOCl solution activated with TOP tip dissolved more soft tissues filled in lateral canals of the canal models, than with passive ultrasonic irrigation and syringe irrigation. Irrigant temperature during TOP tip-induced activation showed a maximum increase of approximately 50˚C near the lateral canal, as measured with thermocouples.
Conclusion: Under the present experimental conditions, TOP tip-induced irrigant activation exerted better cleaning efficacy-related properties than the other methods tested.
(Asian Pac J Dent 2019; 19: 9-15.)
Key Words: diode laser, hot tip, irrigant activation