ABSTRACT
Introduction: The transpalatal arch has been used successfully for decades during routine orthodontic treatment for various purposes, including reinforcing anchorage. In the light of current scientific advancements with more precise knowledge of biology of tooth movement, it is prudent to study whether transpalatal arch is effective in preserving anchorage. Objectives: The aim of this finite element study was to evaluate and compare the effects of the transpalatal arch on periodontal stresses of molars and displacements when subjected to orthodontic forces. Methods: Stress patterns and displacements between models with and without a transpalatal arch were investigated by means of 3-dimensional finite element analysis. A finite element model of the maxillary first molars, periodontal ligament, alveolar bone, and transpalatal arch was created, that consisted of 1, 69,036 elements and 29,518 nodes. A simulated orthodontic retraction force of 2N was applied to the maxillary first molar in a mesial direction. Resultant von mises stresses were evaluated and compared in models with and without transpalatal arch, as well as displacement in models with and without transpalatal arch. Results: Results suggested that the presence of a transpalatal arch has no effect on molar tipping, decreases molar rotations, and reduces periodontal von mises stress magnitudes by less than 1%. Conclusions: The presence of the transpalatal arch induces only minor changes in the dental and periodontal stress distribution. Alternative methods can be used where absolute anchorage is required however transpalatal arch should not be considered an unnecessary tool in the treatment of orthodontic patients because of its various functions.
ABSTRACT
Anchorage plays an important role in orthodontic treatment, especially in the maxillary arch. In spite of many efforts for anchorage control, it was difficult for clinicians to predict the result of treatment because most of the treatment necessitated an absolute compliance of patients. But recently, skeletal anchorage has been used widely because it does not necessitate patient compliance but produces absolute anchorage. In addition, titanium miniscrews have several advantages such as ease of insertion and removal, possible immediate loading and use in limited implantation spaces. In this case, a skeletal Class I bialveolar protrusion patient was treated with standard edgewise mechanics using indirect active P.S.A.(palatal skeletal anchorage). The miniscrews in the paramedian area of the hard palate provided anchorage for retraction of the upper anterior teeth and remained firm and stable throughout treatment. This indicates that the PSA can be used to reinforce anchorage for orthodontic treatment in the maxillary arch. Consequently, this new approach can help effective tooth movement without patient compliance, when used with various transpalatal arch systems.
Subject(s)
Humans , Compliance , Mechanics , Palate, Hard , Patient Compliance , Titanium , Tooth , Tooth Movement TechniquesABSTRACT
砄bjective: To evaluate the effect on a transpalatal arch on reinforcing anchorage. Methods: 12 cases with ClassⅡ Division 1 malocclusion were selected and treated with a transpalatal arch for reinforcing anchorage. Results: ①The forward displacement of the first maxillary molar (6 Ptmo, 6 So, 6CR So and 6AP So) , the backward displacement(1 Ptmo and 1 So ) and the reduction of the axial inclination (1 NA and 1 SN) of the upper incisors were increased( P 0.05);③The forward displacement of the first maxillary molar was less than one third of the extraction space ( P
ABSTRACT
Objective: To analyze the differences of two anchorage ty pe s in closing the space following tooth extraction in maxilla. Methods:By using Spiral CT scanning, image processing and CAD technology, a three -dimensional finite element model of maxilla which could simulate the closing o f space following the extraction of maxillary first bicuspid was established. Ba sed on the model, two loading models were developed, which contained palatal imp lant and transpalatal arch respectively to reinforce the anchorage of molar. Th e two anchorage types were compared and the finite element analysis of closing t he space was performed.Results: The displacement(mm) of the firs t permanent molar in X, Y and Z direction in the model with palatal impl ant was -0.001 162 4,-0.000 901 9 and 0.000 196 2, that in the model with transp alatal arch -0.001 163 7,-0.000 902 2 and 0.000 196 4, respectively(P