| Summary: | 碩士 === 義守大學 === 生物醫學工程學系 === 100 === Periodontal ligaments (PDL) have been considered as an important role in orthodontic treatment to influence tooth movement. This study investigate a basic PDL biomechanics in two cases of regional orthodontic treatment and chewing food particles in complete dentition using three-dimensional finite element (FE) analysis in order to understand the changes and distributions of stress and strain in the PDL under orthodontic and biting forces. The regional orthodontic FE models of the three-teeth, five-teeth, and seven-teeth simulations were used to investigate a treated effect of canine labial protrusion. A 2N orthodontic force was applied at the cross-sections of orthodontic wire to simulate metal elastic effect and condylar processes was fixed as boundary condition. The FE models of complete dentition in the maxilla and mandible with and without missing tooth were investigate to understand effects of the PDL, loading condition was applied by the muscular forces of jaw closing and boundary condition was fixed at cranial base and other skull regions. The result showed that tooth quantity could directly influence the deformation and strain distribution of the PDL, further comparing three FE models of orthodontics to obtain the PDL of the three-teeth FE model possessed the biggest strain and deformation. For investigating chewing food particles in the complete dentition, the principle stress and strain of the PDL in the missing tooth FE model was detected larger than that of non-missing one. The PDL of neighbor teeth due to missing tooth were obviously detected the higher strain and stress intensity, the tendency of principle stress could provide detail location of distribution of tensile and compressive stress within the PDL and alveolar bone around neighbor teeth. The relationship between bone remodeling and strain distribution in the PDL is an important factor to influence tooth movement of orthodontic treatment. Furthermore, The PDL in mesial and distal side around neighbor teeth were significantly detected higher strain and stress concentration for the missing tooth FE model of chewing food particle, this may be explained why neighbor teeth has a trend toward mesial-distal tipping and repair in teeth bridge and dental implant is needed.
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