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cosmetic dentistry - beauty & science

I 29 case report _ orthodontic I cosmeticdentistry 2_2012 _Surgical technique The choice of technique for the osteotomy depends on various factors. In displacement os- teotomy, surgical access to the bone is created, which is split at fixed points. Correction of the bone and bone healing in the new fixed position is accomplished using simulated cast surgery and a fabricated splint. Following surgical modification of the jaw area, it is important to consider the correct posi- tion of the jaw and optimal occlusion. This cru- cial step has to be performed by the orthodontist as accurately as possible because repositioning and the degree of displacement of the jaw depend on achievable occlusion. Furthermore, teeth have an influence on access to the surgical field and wisdom teeth must be removed before osteotomy in certain cases. Osteotomy can be done on both jaws or can be limited to the maxilla or mandible. However, in many cases it is functional to perform bimax- illary osteotomy and to shift both jaws. Today, generally the entire tooth-bearing portions of the jaw are shifted. Segmental osteotomy has not been proven to be very successful in the past and corrections ofmalocclusionsarelefttotheorthodontictreat- ment partners. In this field of treatment, the Obwegeser–Dal Pont surgical technique is rec- ommended. This procedure describes an intra- oral stepped osteotomy at the mandibular ramus (Figs. 7a & b). Since Bell and Epker described the possibility of bimaxillary surgery as the “down fracture” technique in 1975, it has been popular and today you can find it mostly as a combination of Obwegeser–Dal Pont and Le Fort I osteotomy. The bimaxillary approach seems reasonable, since the maxilla and mandible influence each other during growth. However, it is frequently only possible to obtain a very good and risk-free result by using Obwegeser–Dal Pont surgery. Fixation in split osteotomy of the mandible is usually realised by using minimally invasive plate osteosynthesis. In modified techniques of Obwegeser–Dal Pont surgery, a displaced ra- mus is fixed using osteosynthesis screws only (Hochban 1997; Figs. 8a & b). This modification avoids the complicated surgical removal of os- teosynthesis plates. Fig. 6a_View of the casts in the articulator after successful simulation of surgery. Figs. 6b & c_Intra-op fixation of the splint for correction of latero-gnathia after osteotomy. Figs. 7a & b_Illustration of Obwegeser–Dal Pont osteotomy of the 20-year-old patient: split osteotomy of the intra-oral ramus is clearly visible. Figs. 8a & b_Intraoperative view view of osteosynthesis screws inserted during surgery of the 20-year-old patient. Fig. 6a Fig. 7b Fig. 8a Fig. 8b Fig. 6b Fig. 6c Fig. 7a