RESUMEN
INTRODUCTION: The aim of this study was to use the finite element method to evaluate the distribution of stresses and strains on the local bone tissue adjacent to the miniplate used for anchorage of orthodontic forces. METHODS: A 3-dimensional model composed of a hemimandible and teeth was constructed using dental computed tomographic images, in which we assembled a miniplate with fixation screws. The uprighting and mesial movements of the mandibular second molar that was anchored with the miniplate were simulated. The miniplate was loaded with horizontal forces of 2, 5, and 15 N. A moment of 11.77 N·mm was also applied. The stress and strain distributions were analyzed, and their correlations with the bone remodeling criteria and miniplate stability were assessed. RESULTS: When orthodontic loads were applied, peak bone strain remained within the range of bone homeostasis (100-1500 µ strain) with a balance between bone formation and resorption. The maximum deformation was found to be 1035 µ strain with a force of 5 N. At a force of 15 N, bone resorption was observed in the region of the screws. CONCLUSIONS: We observed more stress concentration around the screws than in the cancellous bone. The levels of stress and strain increased when the force was increased but remained within physiologic levels. The anchorage system of miniplate and screws could withstand the orthodontic forces, which did not affect the stability of the miniplate.
Asunto(s)
Placas Óseas , Análisis de Elementos Finitos , Imagenología Tridimensional/métodos , Mandíbula/fisiología , Métodos de Anclaje en Ortodoncia/instrumentación , Técnicas de Movimiento Dental/instrumentación , Fenómenos Biomecánicos , Remodelación Ósea/fisiología , Resorción Ósea/fisiopatología , Simulación por Computador , Homeostasis/fisiología , Humanos , Miniaturización , Modelos Biológicos , Diente Molar/patología , Diseño de Aparato Ortodóncico , Estrés Mecánico , Propiedades de Superficie , Tomografía Computarizada por Rayos X/métodosRESUMEN
BACKGROUND: Overeruption of an upper molar following loss of the opposing tooth is a common clinical finding. Rehabilitation can be difficult when the interocclusal space is reduced. AIM: To intrude an overerupted upper first molar and replace the missing lower first molar. METHODS: Buccal and palatal microscrews and a transpalatal bar were placed. The palatal miniscrew loosened shortly after implantation and was not replaced. A short length of elastomeric chain from the buccal miniscrew applied 30 g of force to the overerupted molar. The elastomeric chain was replaced every four weeks. RESULTS: Sufficient intrusion of the upper molar was obtained in 4 months. CONCLUSION: A single buccal microscrew and transpalatal arch can be used to intrude an overerupted upper molar.
Asunto(s)
Tornillos Óseos , Métodos de Anclaje en Ortodoncia/instrumentación , Técnicas de Movimiento Dental/métodos , Implantación Dental Endoósea , Análisis del Estrés Dental , Femenino , Humanos , Persona de Mediana Edad , Miniaturización , Diente Molar/fisiopatología , Aparatos Ortodóncicos , Erupción DentalRESUMEN
Mucocele é um termo utilizado para diagnosticar clinicamente dois fenômenos que podem acometer as glândulas salivares menores, sendo eles: o fenômeno de extravasamento e o cisto de retençäo mucoso. Embora essas lesöes sejam muito freqüentes na cavidade bucal, existe ainda certa confusäo em relaçäo a esses termos. Os autores relatam um caso clínico de mucocele, discutindo a etiopatogenia e as características clínicas que levaram ao diagnóstico clínico da lesäo, bem como o prognóstico, o tratamento e as características histológicas da mesma