The effect of coronoidotomy in relapse prevention of Intraoral vertical ramus osteotomy

Abstract

Intraoral vertical ramus osteotomy (IVRO) is one of the main techniques used to treatment of mandibular prognathism. Advantages of IVRO include lower incidence of inferior alveolar nerve injury and technical simplicity. The effect of the temporalis on relapse has led to other recommendations that include either stripping the temporalis attachment completely off the coronoid or cutting off the coronoid. The use of this latter coronoidotomy has been recommended by some clinicians for large setbacks, with a few using this modification routinely. This study aimed at evaluating the effect of coronoidotomy in relapse prevention of IVRO. Methods & Materials: In a randomized clinical trial, 60 candidates of the IVRO with mandibular prognathism were recruited in Tabriz Imam Reza, Zakaria, Nejat and Shahriar Hospitals during a 21-month period. These patients were randomized to two groups: the case group underwent the IVRO plus coronoidotomy and the controls underwent the IVRO. The relapse amount was reevaluated by clateral cephalometries one year after surgery and compared between the two groups. Data were evaluated using Independent sample T-test or Mann-Whitney U-test and FisherEs exact test and were compared by SPSS software version 15. P Value less than 0.05 was considered statistically significant. Significant relapse was considered as amounts above 30% of the primary setback. Results: Follow up was accomplished in 27 patients in the case group, 12 males and 15 females with a mean age of 21.62.9 years and in 29 controls, 13 males and 16 females with a mean age of 20.73.5 years (p>0.05). The mean relapse rate was 2.1, 1.9 and 1.8 mm in the B, menton and pogonion points and 1.7 and 1.3 degrees for the ANB and SNB angles in the cases group, respectively. The corresponding readings were 2.5, 2.3 and 2.3 mm and 1.9 and 1.4 degrees in the controls, respectively. The mean relapse amount was significantly lower for the pogonion point in the cases group and the differences were insignificant just in a borderline manner in the B and menton points, as well. A significant amount of relapse was detected in 44.4% to 70.4% of the cases in different points and in 62.1% to 72.4% of the controls, with no significant difference. There was a significant positive correlation between the amount of relapse and the primary setbacks in both groups. Conclusion: According to our results, the IVRO plus coronoidotomy is slightly superior to the single IVRO in treating mandibular prognathism. Further studies are recommended in this regard.