Objectives: This study statistically observed the difference of recovery process influenced by the degree of sensory disturbance after sagittal split ramus osteotomy (SSRO).
Methods: The subjects were those who underwent SSRO, and the sensory test using Semmes-Weinstain monofilaments was conducted before and after the operation (1, 4, 8, 12 and 24 weeks after operation). Among these cases, 168 sides (106 patients) which showed a threshold rise from the preoperative value at one week after the operation were defined as sensory disturbances. These were classified into four levels (levels 1-4) according to Bell's interpretation scale. Statistical analysis was performed on the recovery period for each level and the differences in severity among different levels for each test period.
Results: Regarding the recovery period for each level, significant differences were observed (Friedman: p<0.001). No significant difference in preoperative value was seen 8 weeks after surgery for Level 1, 4 weeks for Level 2, and 24 weeks for Level 3. However, a significant difference existed at 24 weeks after surgery for Level 4 (Wilcoxon: p<0.01).In the comparison of levels for each test period, significant differences were observed for all test periods, except for before surgery (Kruskal-Wallis: p<0.01). Postoperatively, significant differences existed between Level 1 and Levels 3-4 for all test periods, and between Level 1 and Level 2 at all test periods except for 8 weeks after surgery (Mann-Whitney: p<0.01).
Conclusions: It was found that the difference in recovery period and recovery extent is influenced by the difference in level. This suggests that analysis of the recovery period with respect to degree of sensory disturbance should be useful for predicting Prognosis.