RESUMEN
INTRODUCTION: This study aimed to determine and compare the effectiveness of the use of the dual-dimensional archwire and conventional rectangular archwire on tooth movement patterns when combined with various lengths of power arms. METHODS: Displacements of the maxillary central incisor and the deformation of the wire section were calculated when applying retraction forces from different lengths of power arms using the finite element method. RESULTS: Torque control of the incisor could be carried out more effectively when using the dual-dimensional archwire combined with long power arms than with the rectangular archwire. The use of the dual-dimensional archwire produced bodily movement of the central incisor at height levels of the power arm between 8 and 10 mm and lingual root tipping at the level of 10 mm. CONCLUSIONS: The use of the dual-dimensional archwire provided better-controlled movement of the incisor, including bodily movement or root movement, than the rectangular archwire.
Asunto(s)
Análisis de Elementos Finitos , Incisivo , Diseño de Aparato Ortodóncico , Alambres para Ortodoncia , Técnicas de Movimiento Dental , Técnicas de Movimiento Dental/instrumentación , Técnicas de Movimiento Dental/métodos , Humanos , Fenómenos Biomecánicos , Torque , Maxilar , Análisis del Estrés Dental/métodosRESUMEN
INTRODUCTION: Although many studies investigating the mechanical behavior of loop mechanics have focused on loop designs to produce a higher moment-to-force ratio, few studies have clarified the effect of loop position on the force system and resultant tooth movements. This study aimed to simulate orthodontic tooth movements during space closure and to compare the effects of loop position in association with different degrees of gable bend on tooth movements using the finite element method. METHODS: Two finite element models of the maxillary dentition were constructed, with the loop placed mesial or distal to the canine. Tooth movements during loop activation were simulated while varying the degree of gable bend. RESULTS: When the loop was placed distal to the canine, the incisor showed uncontrolled tipping even with the gable bend. Placement of the loop mesial to the canine produced controlled tipping or root movement of the incisor, depending on the degree of gable bend. CONCLUSIONS: Placement of the closing loop mesial to the canine in combination with the incorporation of a gable bend into the archwire distal to the canine could provide better control of incisor movements, such as controlled tipping or root movement, as compared with placement of a gable bend into the loop located distal to the canine.
Asunto(s)
Alambres para Ortodoncia , Técnicas de Movimiento Dental , Fenómenos Biomecánicos , Técnicas de Movimiento Dental/métodos , Simulación por Computador , Fenómenos Mecánicos , Análisis de Elementos Finitos , Estrés MecánicoRESUMEN
INTRODUCTION: The objectives of this study were to simulate long-term orthodontic tooth movement in en-masse retraction using the finite element method and investigate the effects of power arms on tooth movements when using a lingual appliance in comparison with a labial appliance. METHODS: A 3-dimensional finite element model of the maxillary dentition was constructed with 0.018-in brackets and 0.016 × 0.022-in stainless steel archwire. An en-masse retraction was performed by applying retraction force at various lengths of the power arm (4, 6, 8, and 10 mm) to the second molar tube, and long-term tooth movements with the lingual and labial appliances were analyzed using the finite element method. RESULTS: Although lingual crown tipping of the incisor was more marked with the lingual appliance than with the labial appliance in the early phase of space closure, only a slight difference was evident after space closure. Although the power arm was effective for achieving better-controlled tooth movement and reducing vertical and transverse bowing effects, bodily movement of the incisor could not be achieved, and bowing effects could not be eliminated. CONCLUSIONS: To provide better torque control of the incisor or prevent a vertical bowing effect, the incorporation of extra torque into brackets of incisors was recommended, and the use of power arms for the lingual appliance. To prevent a transverse bowing effect, incorporation of the antibowing bend or application of retraction force from both buccal and lingual sides or temporary skeletal anchorage devices was recommended.