Effect of low-level laser therapy on pain levels in patients with temporomandibular disorders: a systematic review

Temporomandibular disorders (TMD) are characterized by the presence oftemporomandibular joint (TMJ) and/or masticatory muscle pain and dysfunction.Low-level laser is presented as an adjuvant therapeutic modality for the treatment ofTMD, especially when the presence of inflammatory pain is suspected.

Objective

To systematically review studies that investigated the effect of low level lasertherapy (LLLT) on the pain levels in individuals with TMD.

Material and Methods

The databases Scopus, embase, ebsco and PubMed were reviewed from January/2003 toOctober/2010 with the following keywords: laser therapy, low-level laser therapy,temporomandibular joint disorders, temporomandibular joint dysfunction syndrome,temporomandibular joint, temporomandibular, facial pain and arthralgia, with theinclusion criteria for intervention studies in humans. exclusion criteria adoptedwere intervention studies in animals, studies that were not written in english,Spanish or Portuguese, theses, monographs, and abstracts presented in scientificevents.

Results

After a careful review, 14 studies fit the criteria for inclusion, of which, 12used a placebo group. As for the protocol for laser application, the energydensity used ranged from 0.9 to 105 J/cm², while the power densityranged from 9.8 to 500 mW. The number of sessions varied from 1 to 20 and thefrequency of applications ranged from daily for 10 days to 1 timeper week for 4 weeks. A reduction in pain levels was reportedin 13 studies, with 9 of these occurring only in the experimental group, and 4studies reporting pain relief for both the experimental group and for the placebo.

Conclusion

Most papers showed that LLLT seemed to be effective in reducing pain from TMD.However, the heterogeneity of the standardization regarding the parameters oflaser calls for caution in interpretation of these results. Thus, it is necessaryto conduct further research in order to obtain a consensus regarding the bestapplication protocol for pain relief in patients with TMD.