Effect of 1,440-nm Nd:YAG Laser Irradiation on Pain and Neuropeptide/Cytokine Reduction from the Teeth with Persistent Apical Periodontitis

Abstract

Introduction The purpose of this study was to investigate the efficacy of a 1,440-nm Nd:YAG laser on relieving pain in relation to the levels of neuropeptides and inflammatory cytokine in the root canal exudates of the teeth with persistent symptomatic apical periodontitis.

Materials and methods Forty patients referred for further management and treatment of the teeth with persistent symptomatic apical periodontitis were randomly assigned to treatment groups: group L, intracanal irradiation of 1,440-nm Nd:YAG laser with a 300-μm-diameter fiber-optic tip in addition to conventional root canal re-treatment

group C, conventional root canal re-treatment. The degrees of both spontaneous pain and pain on percussion before and after treatment were recorded (VAS

visual analogue scale), and root canal exudate samples were collected to quantify the associated levels of substance P (SP), calcitonin gene-related peptide (CGRP), and matrix metalloproteinase (MMP)-8 by immunoassay. The effect of experimental treatment procedures on pain relief (VAS scores) and the changes in SP, CGRP, and MMP-8 concentration (%), and the differences among experimental treatment groups were analyzed. The correlations between the degree of perceived pain (VAS scores of spontaneous pain and pain on percussion) and the levels of SP, CGRP, and MMP-8 in the root canal exudates were analyzed as well. The level of significance was set at 5%.

Results All of the measured parameters were significantly reduced in group L (p < .05), while the levels of pain on percussion, CGRP and MMP-8 were significantly reduced in group C (p < .05). The 1,440-nm Nd:YAG laser had significantly better effect on the relief of pain on percussion and the reduction of SP, CGRP and MMP-8 levels in root canal exudate. The VAS scores of perceived pain correlated with pain-related neuropeptides and inflammatory cytokine levels in root canal exudates. SP levels correlated directly with CGRP levels (p < .05).

Conclusions The 1,440-nm Nd:YAG laser irradiation via fiber-optic tip to the teeth with persistent apical periodontitis provided promising consequences of pain and inflammation modulation.