The purpose of this study was to analyse the center of resistance of the maxillary first molar using the 3-dimension finite element method. An extrated maxillary first molar of normal shape and average root length was selected and sectioned every
1.5mm
parallel to the cementoenamel junction. Each section was traced and digitized to construct3-D finite element model of the maxillary first molar. After a certain magnitude of of counterbalancing moment(M) applied to the tooth, a varying single
force
(F)
of distomesial direction was applied to a certain point of the tooth until the tooth was translated. The force producing translation (Ft) was substiuted to the equation △d=M/Ft to calculate the center of resistance of the maxillary first molar.
And
reducing the alveolar bone level 1.68mm, and 3.36mm below to the cementoenamel junction, the tooth movement was analysed to see the effect of reducing the alveolar bone level to the location of the center of resisitance.
The results were as follows ;
1. The center of r3esistance of the maxillary first molar was 3.72mm apical, 1.10mm buccal, and 0.71mmmesial to the geometric center of the horizontally sectioned surface at the cementoenamel junction. This point was 0.36mm apical, 1.20mm
buccal,
and
0.71mm mesial to the trifurcation point, indicating that it was not on the tooth root.
2. As the alveolar bone level was reduced, the center of resistance of the maxillary first molar was was moved to the apical direction.
KOREA J ORTHOD 1993;2392) :263-273.
|