Effect of low-level laser treatment on neurosensory deficits subsequent to sagittal split ramus osteotomy

Low-level laser treatment has been advocated as a possible treatment for patients with paresthesia. An objectively verified improvement in sensory function is relevant if, at the same time, it is perceived as a subjective improvement by the patient. The aim of this double blind clinical study was to see if low-level laser treatment with a GaAlAs laser (820 nm, Rønvig, Denmark) resulted in objectively verified improvement in sensory function and whether this correlated with the patient's subjective evaluation subsequent to treatment.

The 13 patients in this study had all undergone saggittal split ramus osteotomy resulting in either compression or traction of the inferior alveolar nerve as reported by the surgery notes. The material was collected from a consecutive series of patients at the Karolinska Hospital, all of whom had shown reduced sensibility at their final 2-year postoperative checkup. The patients were randomly divided into two groups; one (eight subjects) group received real low-level laser treatment (4 x 6 J per treatment along the distribution of the inferior alveolar nerve, at the following points extraoral: lateral third of lower lip, intraoral; buccally to the apex of the second premolar tooth and the apex of the second molar tooth; lingually in the region of the mandibular foramen; for a total of 20 treatments). The other group received an equivalent placebo treatment. The study was conducted in a double blind fashion for both patient and doctor as the low-level laser equipment had two settings, A and B, one of which was an unknown void setting. The degree of mechanoceptor neurosensory deficit was assessed by Semmes Weinstein monofilaments (North Coast Medical, USA) and the degree of thermoceptor neurosensory deficit was assessed by a Thermotester (Somedic, Sweden). The degree of subjective neurosensory deficit was assessed by means of a visual analogue scale. Both variables and the degree of subjective injury were comparable between the two groups before starting treatment.

The patients in the real low-level laser treatment group experienced a subjective improvement in both lip (p = 0.01) and chin (p = 0.02) after completion of the course of treatment. In addition, this group showed a significant decrease in the area of mechanoperception neurosensory deficit (p = 0.01) compared with no difference in the placebo group. The real low-level laser treatment group exhibited a strong tendency toward improvement in mechanoreceptor neurosensory deficit in the areas of most damage for both lip and chin. This improvement was especially pronounced in the lip region (p = 0.06). No similar tendency was demonstrated in the placebo group. Neither group showed any significant change or tendency to improvement in thermoception on completion of the course of treatment.

In conclusion GaAlAs low-level laser treatment results in both a subjective and objective improvement in mechanical sensory perception in long-standing neurosensory deficit in the inferior alveolar nerve.