Yang Shi1,2, Chao-Ning Zhu3, Zhijian Xie4,5. 1. Department of Oral and Maxillofacial Surgery, The Affiliated Stomatology Hospital, Zhejiang University School of Medicine, No. 395, Yan'an Rd, 310003, Hangzhou, China. 2. Key Laboratory of Oral Biomedical Research of Zhejiang Province, Zhejiang University, 310003, Hangzhou, China. 3. State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, 310058, Hangzhou, China. 4. Department of Oral and Maxillofacial Surgery, The Affiliated Stomatology Hospital, Zhejiang University School of Medicine, No. 395, Yan'an Rd, 310003, Hangzhou, China. xzj66@zju.edu.cn. 5. Key Laboratory of Oral Biomedical Research of Zhejiang Province, Zhejiang University, 310003, Hangzhou, China. xzj66@zju.edu.cn.
Abstract
OBJECTIVE: The present study compared the skeletal effects of surgically assisted rapid maxillary expansion (SARME) with different surgeries in three representative finite element (FE) models. STUDY DESIGN: According to the ossification level of midpalatal suture, three FE models, with different elasticity moduli of sutures (E = 1 MPa, 500 MPa, and 13,700 MPa) were constructed, to represent three age groups of patients. Within each model, four groups were set up according to different surgeries: group I (control group without surgery), II (paramedian osteotomy), III (pterygomaxillary separation), and IV (paramedian osteotomy and pterygomaxillary separation). An expansion force of 100 N and 1 mm displacement were applied via a bone-borne distraction to simulate the expansion process. RESULTS: By analyzing these models, the maximum displacement of maxilla was observed in group IV, with E = 1 MPa model exhibiting the most displacement (28.5 × 10-6 mm), followed by group II (21.4 × 10-6 mm). Group IV showed a unique backward-downward rotation with minimum stress distributions in three models (9 MPa, 131 MPa, and 140 MPa, respectively), and group II exhibited comparable low stress distributions (12 MPa, 151 MPa, and 230 MPa, respectively). Lowest stress was found in E = 1 MPa model, compared with the other two models. CONCLUSION: There is no need to perform surgeries when the midpalatal suture is open, and surgery guidelines are the same for partial and complete fusion sutures. Furthermore, exclusive use of partial paramedian osteotomy is sufficient enough to reduce stress and expand the posterior part of maxilla, and it is less invasive.
OBJECTIVE: The present study compared the skeletal effects of surgically assisted rapid maxillary expansion (SARME) with different surgeries in three representative finite element (FE) models. STUDY DESIGN: According to the ossification level of midpalatal suture, three FE models, with different elasticity moduli of sutures (E = 1 MPa, 500 MPa, and 13,700 MPa) were constructed, to represent three age groups of patients. Within each model, four groups were set up according to different surgeries: group I (control group without surgery), II (paramedian osteotomy), III (pterygomaxillary separation), and IV (paramedian osteotomy and pterygomaxillary separation). An expansion force of 100 N and 1 mm displacement were applied via a bone-borne distraction to simulate the expansion process. RESULTS: By analyzing these models, the maximum displacement of maxilla was observed in group IV, with E = 1 MPa model exhibiting the most displacement (28.5 × 10-6 mm), followed by group II (21.4 × 10-6 mm). Group IV showed a unique backward-downward rotation with minimum stress distributions in three models (9 MPa, 131 MPa, and 140 MPa, respectively), and group II exhibited comparable low stress distributions (12 MPa, 151 MPa, and 230 MPa, respectively). Lowest stress was found in E = 1 MPa model, compared with the other two models. CONCLUSION: There is no need to perform surgeries when the midpalatal suture is open, and surgery guidelines are the same for partial and complete fusion sutures. Furthermore, exclusive use of partial paramedian osteotomy is sufficient enough to reduce stress and expand the posterior part of maxilla, and it is less invasive.
Authors: Stephan Christian Möhlhenrich; Ali Modabber; Mohammad Kamal; Ulrike Fritz; Andreas Prescher; Frank Hölzle Journal: Oral Surg Oral Med Oral Pathol Oral Radiol Date: 2016-01-03