Effectiveness of low-level diode laser therapy on orthodontic pain management: a systematic review and meta-analysis

Abstract

AIMS: There is controversy on the effectiveness of low-level laser therapy (LLLT) for orthodontic pain relief. Among various LLLT types, a diode laser is most widely employed. This review aimed to assess the effectiveness of diode LLLT for orthodontic pain control. MATERIALS AND METHOD: A systematic and extensive electronic search was performed in the Cochrane Library (Issue 9, 2014), PubMed (1997), Embase (1947) and Web of Science (1956) for randomized controlled trials (RCTs) investigating the effects of diode LLLT for orthodontic pain up to October, 2014. Studies were included according to the selection criteria independently by two reviewers. Risk of bias was assessed by the Cochrane tool for risk of bias evaluation. Meta-analysis was conducted by RevMan 5.3. Effect of intervention was measured in relative risk (RR) for dichotomous outcome and in mean difference (MD) for continuous outcome with a 95 per cent confidence interval (CI). RESULTS: Out of 186 results identified, 14 RCTs were included with a total of 659 participants from 11 countries. Except for three studies, assessed as ‘moderate risk of bias’, others were rated as having a ‘high risk of bias’. Methodological weakness mainly lay in ‘blinding’ and ‘allocation concealment’. Meta-analysis showed that diode LLLT significantly reduced orthodontic pain prevalence by 39 per cent in comparison with placebo groups (RR = 0.61, 95% CI range 0.41 to 0.92, P = 0.02). Regarding pain intensity, a diode laser was shown to reduce maximum pain intensity with the difference significant in studies of parallel design (MD = –3.27, 95% CI range –5.40 to –1.15, P = 0.003 versus placebo groups; MD = –3.25, 95% CI range –4.25 to –2.26, P = 0.000 versus control groups), yet insignificant in studies of split-mouth design (MD = –1.29, 95% CI range –4.20 to 1.61, P = 0.38 versus placebo groups). CONCLUSION: The use of diode LLLT for orthodontic pain looks promising. However, due to methodological weakness and risk of bias, there was insufficient evidence to support or refute its effectiveness. RCTs with a better design and appropriate sample power are required to provide stronger evidence for its clinical application. (Supported by Health and Medical Research Fund 01121056)