Discussion
In 1967, subapical osteotomy was first used by Taylor et al.to treat anterior alveolar protrusion[1]. Anterior maxillary osteotomy (AMO) was performed through the anterior maxillary osteotomy to form tooth 13 to tooth 23 (or tooth 14 to tooth 24) segments of the tooth-bone, including anterior nasal spine and anterior osseous nasal floor. The tooth-bone segment was often retreated or moved upward to correct maxillary anterior teeth and alveolar bone deformities. However, the procedure adopted in our case was an unconventional anterior maxillary osteotomy. The tooth 14-24 tooth-bone segment was incised and moved forward and downward to improve the patient’s Class III bone profile as well as to increase the mesiodistal space of missing tooth 15 and 25.
In this case, anterior maxillary osteotomy and anterior displacement can greatly simplify the surgical approach, increase the mesiodistal distance of the missing tooth area, provide enough space for implant restoration, and achieve good aesthetic and functional effects. In our case, the anterior maxillary osteotomy was performed with a labial vestibular incision. Therefore, The blood supply of free tooth-bone mass was mainly provided by the palatal periosteum, and the palatine periosteum was relatively compact, so the bone mass was moved forward in a limited range. After operation, the osteotomy block healed well and the corresponding teeth were free of pain and loosening. The bone and facial shape of the patient was improved effectively. The coordination degree of the upper and lower arches, the mismatch of the midline and the measurement parameters of the lateral position of the skull were obviously improved and reached the normal level basically(Fig.8). During 3 years of follow-up, the therapeutic effect was stable.
At present, autologous bone graft was a common method to solve serious bone defects and it was characterized by good bone guidance, no immune rejection, good induction of osteoblast differentiation and new bone formation[2]. However, its disadvantage lied in opening up a secondary operation area, which can easily lead to secondary injury and complications in the site of bone extraction, and bone resorption may sometimes occur after bone grafting[3]. In this case, the removed cortical bone fragments, which were obtained by sagittal split ramus osteotomy, were placed in tooth 15 and tooth 25 osteotomy area. After one year of follow-up, we observed the ideal vertical bone height of 16 mm and the mesiodistal distance of 7mm for both tooth 15 and 25 area. However, the absorption of the lip and tongue of bone tissue was more obvious (3mm for both tooth 15 and 25 area). It is attributed to the fact that only limited autogenous bone graft is used in the area of bone graft, no excessive bone graft is performed, and the barrier membrane is not covered by GBR at the same time, and the muscle tension of the buccal region in the region of bone graft is greater after operation[4].
This patient was a complex case with maxillofacial deformity with congenital missing teeth and insufficient implant space which affected the facial appearance and masticatory function. The combined application of orthodontic and orthognathic surgery can solve the Angle III bone facial shape of patients. Meanwhile, the modified orthognathic surgery method increased the mesiodistal space of the missing tooth area and reduced the difficulty of implant repair. In this case, multidisciplinary participation and cooperation resulted in a marked improvement in the patient’s facial appearance and occlusion(Fig.9) Through the development of this case, we believe that for the complex skeletal malocclusion cases which needed implant repair, it was necessary to conduct multidisciplinary consultation before operation, and to establish individualized treatment for patients, in order to achieve the best repair effect.