Finite element analysis of dental aligner

• Main Author: Zhu, Huijuan
• Other Authors: Sellakkutti Rajendran
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/149448
• Institution: Nanyang Technological University

The orthodontic treatment involves adjusting the teeth position to ensure good function and appearance of the teeth. A pair of well-formed teeth with pleasing appearance enables an individual to speak and chew effectively and smile confidently. Over the last ten years, more adults are seeking clear dental aligner treatments as an option for orthodontictreatment as it appears to be more aesthetically pleasing than traditional treatment using braces. The focus of this project isto develop a simulation procedure in using the finite element method (ANSYS) for contact pressure analysis of an aligner-teeth simulation model as well as stress analysis of the aligner. The objective of contact pressure analysis is to determine the amount of force applied by the aligner on the teeth to be moved. The objective of stress analysis is to determine the maximum stress developed in the aligner and its location.For this project, the teeth and gum areassumed to be rigid while the aligner istreated as flexible. The finite element software ANSYS Mechanical APDL isused for the purpose. A literature review on clear dental aligner shows that the published work on finite element analysis of dental aligners is scarce. The actual dental aligner isquite complex in shape/geometry and hence implementing contact conditions at the interface between aligner and teeth is quite challenging. Therefore, as a first step towards the final objective, in this project, a simplified teeth/aligner modelled is analysed. Three different models (with 4, 6 and 8 teeth) are studied with different teeth offset and aligner thickness values. For each model, stress analysis is carried out and thereby contact pressure on the teeth was determined. An APDL code is developed toautomate ANSYS simulation steps so that various combinations of teeth offset, and aligner thickness can be analysed quickly. It is observed that the contact pressure applied by the aligner on the teeth is localised on the central region of the teeth. It is only in this region the aligner contacts the teeth. The contact pressure increases with the teeth offset and aligner thickness. As for the stresses developed in the aligner, high concentration of stress is observed at the sharp fillets in the aligner covering the inter-tooth gaps.