Which factors affect the lingual fracture pattern in sagittal split ramus osteotomy?

The purpose of this study was to elucidate the effects of mandibular anatomy and osteotomy technique on lingual fracture patterns in SSRO. The predictor variables were: length of horizontal medial osteotomy; type of border osteotomy; buccolingual width; and vertical length of the basal cortex. The outcome variable was the type of lingual split pattern. This was categorized into four types according to a lingual split scale (LSS): LSS 1, true Hunsuck; LSS 2, fracture line to posterior border of the ramus; LSS 3, through to mandibular canal; LSS 4, unfavorable fracture pattern. Data were analyzed using analysis of variance and the Pearson χ2 test. Values of p < 0.05 were considered statistically significant. The study sample comprised 312 lingual split patterns in 156 patients. The most common type of lingual split pattern was LSS 1 (n = 204). There was a significant relationship between inferior border osteotomy type and LSS type (p = 0.001). Whilst LSS 1 was the most common among all border osteotomy types. LSS 4 was most frequently observed in cases where the lower border osteotomy remained in the buccal surface. According to the results of this study, the likelihood of an unfavorable split pattern increases when the lower border osteotomy remains in the buccal surface.

Functional genioplasty in growing patients.

OBJECTIVE: To evaluate the role of age as a moderator of bone regeneration patterns and symphysis remodeling after genioplasty. METHOD: Fifty-four patients who underwent genioplasty at the end of their orthodontic treatment were divided into three age groups: younger than 15 years at the time of surgery (group 1), 15 to 19 years (group 2), and 20 years or older (group 3). Twenty-three patients who did not accept genioplasty and had a follow-up radiograph 2 years after the end of their orthodontic treatment were used as a control group. Patients were evaluated at three time points: immediate preoperative (T1), immediate postoperative (T2,) and 2 years postsurgery (T3). RESULTS: The mean genial advancement at surgery was similar for the three age groups, but the extent of remodeling around the repositioned chin was greater in group 1, less in group 2, and still less in group 3. Symphysis thickness increased significantly during the 2-year postsurgery interval for the three groups, and this increase was significantly greater in group 1 than in group 3. Remodeling above and behind the repositioned chin also was greater in the younger patients. This was related to greater vertical growth of the dentoalveolar process in the younger patients. There was no evidence of a deleterious effect on mandibular growth. CONCLUSION: The outcomes of forward-upward genioplasty include increased symphysis thickness, bone apposition above B point, and remodeling at the inferior border. When indications for this type of genioplasty are recognized, early surgical correction (before age 15) produces a better outcome in terms of bone remodeling.