Abstract:

BACKGROUND: Although mini-screws anchorage implant can provide strong anchorage, it cannot control the three-dimensional movement of the tooth. Tomas-pin can be fixed in a square archwire and designed into a cross, in order to control the three-dimensional movement of the tooth. And this research has not been reported.
OBJECTIVE: To investigate the effects of combined force for maxillary second molar uprighting with micro-implant anchorage system.
METHODS: Maxillary second molar and tipped mesiobuccally were selected to be the tooth sample, and maxillary which corresponds with sample tooth was also selected to be the alveolar bone sample. Multi-slice spiral CT scanning was taken for both of samples to get legible and accurate image information. A three-dimensional model of maxillary second molar with periodontal tissues was established by finite element software. Effects of embedding position of micro-implant, orientation of the loading force and loading force on the Von Mises stress of the periodontal tissue were investigated.
RESULTS AND CONCLUSION: The maximum stress of the periodontal ligament was detected in the cervix of the maxillary second molar, and the stress was gradually decreased along with the apical. However, stress concentration could not be found in the apex of each root. The finite element model could be exhibited similarity in geometry and biomechanics, and could be used for the precisely biomechanics analysis. The bodily movement or tipping movement can be achieved with Tomas-pin.