Effect of tip insertion depth and irradiation parameters on the efficacy of cleaning calcium hydroxide from simulated lateral canals using Er:YAG laser- or ultrasonic-activated irrigation

Abstract

Background/purpose: Laser-activated root canal irrigation (LAI) with an Er:YAG laser is considered more effective than other irrigation methods, whereas the effectiveness of LAI in cleaning lateral canals far from the laser tip remains unclear. This study aimed to compare the efficacy of removing calcium hydroxide [Ca(OH)2] paste from lateral canals using LAI or ultrasonic-activated irrigation (UAI), and to examine the effect of tip insertion depth and laser irradiation parameters on cleaning efficacy. Materials and methods: Radiopaque Ca(OH)2 paste (Calcipex II) was injected into lateral canals 6 mm from the root apex in 192 J-shaped simulated root canal models. LAI (Erwin AdvErl; 30 or 70 mJ; 10 or 20 pulses per second; laser tip R200T or R600T) and UAI (ENAC SE10; output setting: 3) were performed 3 times for 20 s. The laser tip was placed at 8–0 mm coronal to the lateral canal location. The volume of Ca(OH)2 paste before and after the experiment was measured using micro-CT (SMX-100CT). Results: The Ca(OH)2 removal rate by LAI was significantly higher than UAI at all tip insertion depths. Ca(OH)2 removal rate in LAI was significantly lower at the 8 mm position compared with other positions (P < 0.05). When the tip insertion depth was fixed at this position, Ca(OH)2 removal rate increased significantly when pulse energy and tip diameter were increased (P < 0.05). Conclusion: LAI removed Ca(OH)2 paste from lateral canals away from the tip more effectively than UAI. Increasing the pulse energy and tip diameter improved the removal efficiency.

Keywords

• Calcium hydroxide
• Er-YAG Lasers
• Root canal irrigants
• Root canal therapy
• Ultrasonics