Effect of bone-borne rapid maxillary expanders with and without surgical assistance on the craniofacial structures using finite element analysis.
BACKGROUND
The aim of this study was to analyze stress distribution and displacement of the craniofacial structures resulting from bone-borne rapid maxillary expanders with and without surgical assistance using finite element analysis.


METHODS
Five designs of rapid maxillary expanders were made: a tooth-borne hyrax expander (type A); a bone-borne expander (type B); and 3 bone-borne surgically assisted modalities: separation of the midpalatal suture (type C), added separation of the pterygomaxillary sutures (type D), and added LeFort I corticotomy (type E). The geometric nonlinear theory was applied to evaluate the Von Mises stress distribution and displacement.


RESULTS
The surgical types C, D, and E demonstrated more transverse movement than did the nonsurgical types A and B. The amounts of expansion were greater in the posterior teeth in types A and B, but in types C, D, and E, the amounts of expansion were greater in the anterior teeth. At the midpalatal suture, the nonsurgical types showed more anterior expansion than did the posterior region, and higher stresses than with the surgical types. Type B showed the highest stresses at the infraorbital margin, anterior and posterior nasal spines, maxillary tuberosity, and pterygoid plate and hamulus.


CONCLUSIONS
The 3 surgical models showed similar amounts of stress and displacement along the teeth, midpalatal sutures, and craniofacial sutures. Therefore, when using a bone-borne rapid maxillary expander in an adult, it is recommended to assist it with midpalatal suture separation, which requires minimal surgical intervention.
Private practitioner, Jeju, Korea.
Seong Cheon
SC
Lee
Associate professor and chair, Postgraduate Orthodontic Program, Arizona School of Dentistry & Oral Health, A. T. Still University, Mesa, Ariz; adjunct professor, Graduate School of Dentistry, Kyung Hee University, Seoul, Korea.
Jae Hyun
JH
Park
Research assistant professor, Graduate School, Catholic University of Korea, Seoul, Korea; visiting professor, Department of Postgraduate Studies, Universidad Autonóma del Paraguay, Asunción, Paraguay.
Mohamed
M
Bayome
Associate professor, Department of Orthodontics, Center for Advanced Dental Education, Saint Louis University, St Louis, Mo.
Ki Beom
KB
Kim
Professor, Department of Orthodontics, Center for Advanced Dental Education, Saint Louis University, St Louis, Mo.
Eustaquio A
EA
Araujo
Professor, Department of Orthodontics, Seoul Saint Mary's Hospital, Catholic University of Korea, Seoul, Korea. Electronic address: kook190036@yahoo.com.
Yoon-Ah
YA
Kook
D000328:Adult; D000539:Alveolar Process / Q000473:pathology; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D017076:Computer-Aided Design; D003393:Cranial Sutures / Q000473:pathology; D005147:Facial Bones / Q000473:pathology*; D020342:Finite Element Analysis; D005624:Frontal Bone / Q000473:pathology; D006801:Humans; D008437:Maxilla / Q000473:pathology / Q000601:surgery*; D008953:Models, Anatomic; D008954:Models, Biological; D009295:Nasal Bone / Q000473:pathology; D017711:Nonlinear Dynamics; D009915:Orbit / Q000473:pathology; D016382:Orthodontic Appliance Design; D019340:Osteotomy, Le Fort / Q000379:methods; D010155:Palatal Expansion Technique / Q000295:instrumentation*; D013100:Sphenoid Bone / Q000473:pathology / Q000601:surgery; D013314:Stress, Mechanical; D014070:Tooth / Q000473:pathology; D015050:Zygoma / Q000473:pathology