Kwang Yoo Kim1, Mohamed Bayome2, Jae Hyun Park3, Ki Beom Kim4, Sung-Seo Mo5, Yoon-Ah Kook6. 1. *Department of Dentistry, Graduate School and. 2. **Department of Dentistry, College of Medicine, Catholic University of Korea, Seoul, Korea, ***Department of Postgraduate Studies, Universidad Autonóma del Paraguay, Asunción, Paraguay. 3. ****Postgraduate Orthodontic Program, Arizona School of Dentistry and Oral Health, A.T. Still University, Mesa, USA, *****Graduate School of Dentistry, Kyung Hee University, Seoul, Korea. 4. ******Department of Orthodontics, Center for Advanced Dental Education, St. Louis University, MO, USA. 5. **Department of Dentistry, College of Medicine, Catholic University of Korea, Seoul, Korea. 6. *******Department of Orthodontics, Seoul St. Mary's Hospital, College of Medicine, Catholic University of Korea, Seoul, Korea kook190036@yahoo.com.
Abstract
OBJECTIVES: The aim of this study was to analyse the displacement and stress distribution in the maxillofacial complex during maxillary protraction with buccal and palatal plates using three-dimensional finite element analysis. MATERIALS AND METHODS: Three anchorage appliance models-palatal plate (Type A), miniplate at the infrazygomatic crest (Type B), and conventional tooth-borne appliance (Type C)-were designed and integrated into a skull model. Protraction force was 500 g per side and force direction was forward and 30 degree downward to the maxillary occlusal plane. The stress distribution around the circum-maxillary sutures and the displacement of the surface landmarks were analysed. RESULTS: All models showed forward and upward displacement at anterior nasal spine, Point A, and prosthion and forward and downward displacement at posterior nasal spine resulting in a counter-clockwise rotation. This anterior displacement was greatest in Type A. At the maxillary process of the zygoma, upward movement was shown only in Type A, whereas downward movement was observed in Types B and C. The greatest stresses in Type A were at the pterygomaxillary and the zygomaticotemporal sutures. Type B showed the greatest stress at the frontomaxillary suture. LIMITATIONS: Type A showed asymmetric results; however, it was not of clinical significance. CONCLUSION: The palatal plate resulted in wider stress distribution and more forward displacement compared to miniplate at the infrazygomatic crest area and conventional tooth-borne appliances. It might be recommended to consider the application of the palatal plate for maxillary protraction in Class III patients.
OBJECTIVES: The aim of this study was to analyse the displacement and stress distribution in the maxillofacial complex during maxillary protraction with buccal and palatal plates using three-dimensional finite element analysis. MATERIALS AND METHODS: Three anchorage appliance models-palatal plate (Type A), miniplate at the infrazygomatic crest (Type B), and conventional tooth-borne appliance (Type C)-were designed and integrated into a skull model. Protraction force was 500 g per side and force direction was forward and 30 degree downward to the maxillary occlusal plane. The stress distribution around the circum-maxillary sutures and the displacement of the surface landmarks were analysed. RESULTS: All models showed forward and upward displacement at anterior nasal spine, Point A, and prosthion and forward and downward displacement at posterior nasal spine resulting in a counter-clockwise rotation. This anterior displacement was greatest in Type A. At the maxillary process of the zygoma, upward movement was shown only in Type A, whereas downward movement was observed in Types B and C. The greatest stresses in Type A were at the pterygomaxillary and the zygomaticotemporal sutures. Type B showed the greatest stress at the frontomaxillary suture. LIMITATIONS: Type A showed asymmetric results; however, it was not of clinical significance. CONCLUSION: The palatal plate resulted in wider stress distribution and more forward displacement compared to miniplate at the infrazygomatic crest area and conventional tooth-borne appliances. It might be recommended to consider the application of the palatal plate for maxillary protraction in Class III patients.
Authors: Won Moon; Kimberley W Wu; Matthew MacGinnis; Jay Sung; Howard Chu; George Youssef; Andre Machado Journal: Prog Orthod Date: 2015-06-04 Impact factor: 2.750