Abstract: Two studies assessed as at high risk of bias, reporting data from 26 analysed participants were included in this review. The age range of participants was from 17 to 55 years. Both trials investigated the effectiveness of low-level laser treatment compared to placebo laser therapy on inferior alveolar sensory deficit as a result of iatrogenic injury. Patient-reported altered sensation was partially reported in one study and fully reported in another. Following treatment with laser therapy, there was some evidence of an improvement in the subjective assessment of neurosensory deficit in the lip and chin areas compared to placebo, though the estimates were imprecise: a difference in mean change in neurosensory deficit of the chin of 8.40 cm (95% confidence interval (CI) 3.67 to 13.13) and a difference in mean change in neurosensory deficit of the lip of 21.79 cm (95% CI 5.29 to 38.29). The overall quality of the evidence for this outcome was very low; the outcome data were fully reported in one small study of 13 patients, with differential drop-out in the control group, and patients suffered only partial loss of sensation. No studies reported on the effects of the intervention on the remaining primary outcomes of pain, difficulty eating or speaking or taste. No studies reported on quality of life or adverse events. The overall quality of the evidence was very low as a result of limitations in the conduct and reporting of the studies, indirectness of the evidence and the imprecision of the results. There is clearly a need for randomised controlled clinical trials to investigate the effectiveness of surgical, medical and psychological interventions for iatrogenic inferior alveolar and lingual nerve injuries. Primary outcomes of this research should include: patient-focused morbidity measures including altered sensation and pain, pain, quantitative sensory testing and the effects of delayed treatment.

Plain-language summary: The Cochrane Oral Health Group carried out this review, and the evidence is current as of 9 October 2013. There are two studies included, both published in 1996, which compared low-level laser treatment to placebo or fake treatment for partial loss of sensation following surgery to the lower jaw. There were 15 participants in one study and 16 in the other, their ages ranging from 17 to 55 years. All had suffered accidental damage to nerves of the lower jaw and tongue causing some loss of sensation following surgery. Low-level laser therapy was the only treatment to be evaluated in the included studies and this was compared to fake or placebo laser therapy. No studies were found that evaluated other surgical, medical or counselling treatments. There was some evidence of an improvement when participants reported whether or not sensation was better in the lip and chin areas with low-level laser therapy. This is based on the results of a single, small study, so the results should be interpreted with caution. No studies reported on the effects of the treatment on other outcomes such as pain, difficulty eating or speaking or taste. No studies reported on quality of life or harm. The overall quality of the evidence is very low as a result of limitations in the conduct and reporting of the two included studies and the low number of participants, and evidence from participants with only partial sensory loss.