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 (Eâ¯= 1â¯MPa, 500â¯MPa, and 13,700â¯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 100â¯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 Eâ¯= 1â¯MPa model exhibiting the most displacement (28.5â¯× 10-6â¯mm), followed by group II (21.4â¯× 10-6â¯mm). Group IV showed a unique backward-downward rotation with minimum stress distributions in three models (9â¯MPa, 131â¯MPa, and 140â¯MPa, respectively), and group II exhibited comparable low stress distributions (12â¯MPa, 151â¯MPa, and 230â¯MPa, respectively). Lowest stress was found in Eâ¯= 1â¯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.