Şeffaf Plak Tekniğinde Kullanılan Farklı Kompozit Ataşmanların ve Üçüncü Molar Varlığının Maksiller Molar Distalizasyonuna Etkisinin Sonlu Elemanlar Metodu ile İncelenmesi
Özet
KUĞUOĞLU A. Investigation of The Effect of Different Composite Attachments Used and The Presence of The Third Molar on Maxillary Molar Distalization in The Clear Aligner Technique Using The Finite Element Method. Hacettepe University, Faculty of Dentistry, Department of Orthodontics, Specialty Thesis, Ankara, 2023. Aim: The aim of our study is to examine the effect of the presence of the third molar during second molar distalization with the clear aligner technique using FEM (Finite Element Method) and to compare the effects of different attachment configurations during distalization and simultaneous expansion with distalization with the clear aligner technique by examining them with FEM. Material Method: A digital model of the maxilla, including the maxillary teeth, periodontal ligaments of the teeth and maxillary alveolar bone, was created using CBCT (Cone Beam Computed Tomography) images in DICOM (Digital Imaging and Communication in Medicine) format and intraoral scan images in STL (Standard Triangle Language) format of the patient who met the admission conditions for our study. Maxilla, clear aligner and attachment digital models were assembled independently on the same coordinate axis and imported into Ansys® 19.2 (Ansys, Inc., Canonsburg, PA) to create the finite element model. Two different finite element models were produced. In Model I, all maxillary teeth are present except the right third molar tooth, and the right and left sides are symmetrical with each other except the left third molar tooth. A vertical rectangular attachment (first attachment configuration) was placed on the buccal surface of the right and left second molars. In Model II, all maxillary teeth are present except the third molar teeth, and the right and left side are symmetrical to each other. On the buccal surface of the right second molar tooth, there are two semi-elliptical convex attachments (second attachment configuration) located at right angles to the occlusal plane, with their flat surfaces in opposite directions. On the buccal and palatal sides of the left second molar, there is a semi-elliptical convex attachment (third attachment configuration), whose flat surfaces are in opposite directions and make an angle of 45° and 135° with the occlusal plane. Finite element analysis was performed for three different scenarios. In Scenario I, bilateral 0.25 mm distalization of second molars with first attachment configuration with clear aligner was simulated using model I. In Scenario II, bilateral 0.25 mm distalization of second molars with clear aligner was simulated using model II. In Scenario III, using model II, bilateral 0.25 mm distalization of the second molars with clear aligner and simultaneous 0.5 mm dental expansion for the right and left sides in the second molar teeth area were simulated. In the first scenario, the effect of the third molar tooth on distalization was examined, in the second scenario, three attachment configurations were compared with each other, and in the third scenario, the second and third attachment configurations were compared with each other. Results: The findings of the first scenario showed that when the third molar tooth was present, the maximum total displacement decreased by 17% and the distal displacement at different points of the crown decreased by 10-22%. The presence of the third molar decreased distal tipping and increased distopalatinal rotation. When the efficiencies of the three attachment configurations in the first and second scenarios were compared, the maximum total displacement, distal displacements and distal tipping of the first and second attachment configurations were similar and greater than the third attachment configuration. Among the three attachment configurations, the third attachment configuration provided the most parallel tooth movement with the least distal tipping and negligible buccal tipping and distopalatinal rotation. Comparing the efficiencies of the two attachment configurations in the third scenario, the maximum total, distal, and buccal displacement of the third attachment configuration is approximately twice that of the second attachment configuration. Likewise, the buccal, distal tipping and axial rotation shown by the third attachment configuration are greater than the second attachment configuration. Axial rotations in both attachments were in the distobuccal direction. The second attachment configuration provided more parallel tooth movement with less displacement. Conclusion: The presence of a maxillary third molar tooth reduced the distalization of the maxillary second molar tooth with clear aligners by at least 1/10. Therefore, orthodontic extraction of third molars before maxillary molar distalization with clear aligners is a rational decision in terms of effectiveness and speed of treatment. With clear aligner, the third attachment configuration exhibited the least displacement and the most parallel movement during molar distalization, and the second attachment configuration exhibited the most parallel movement during molar distalization and expansion. When choosing attachments for these two tooth movements, factors such as the rotation and axial inclinations of the tooth, the amount of bone supporting the tooth, and the health of the roots should be taken into consideration.
