| Summary: | 碩士 === 長庚大學 === 顱顏口腔醫學研究所 === 98 === Purpose: To evaluate the bracket/enamel interfacial mechanics withdifferent adhesives and debonding techniques by using finite element analysis, and to predict which kind of adhesive or debonding technique will most likely to cause enamel damage.
Material and methods：(1)Measure the Young’s modulus, Possion’s ration and fracture strength of Transbond XT and Unite by shear force testing. The results would be used in FEA in this study. (2)Create a premolar finite element model; this model was consisted with 6240 nodes and 6157 elements. We recorded the stress distribution when we applied 1N in 2 type of adhesives (Transbond XT & Unite) and 3 type of loading modes(tensile, shear, and torsion forces). (3) To test and verify the results of FEA by shear force testing.
Results: (1)The Young’s modulus, Possion’s ration, and fracture strength of Transbond XT and Unite was 8823MPa, 0.25, 52.58±5.59 MPa and 9470MPa, 0.26, 14.58±2.84 MPa, respectively. (2)The tensile, shear, torsion debonding force of Transbond XT and Unite was 57.32N, 103.65N, 105.35N and15.47 N, 28.45N, 28.97N, respectively; the stress
concentrated area for tensile force was within the adhesive layer; for shear force was in the enamel-adhesive interface; for torsion force was in the adhesive-bracket interface. (3)Shear force testing showed that the debonding force of Transbond XT was larger than Unite.
Conclusions: (1)Because the shear debonding force was large and the stress was concentrated in enamel-adhesive interface, shear force was most likely to induce enamel damage. (2)Transbond XT was most likely to induce enamel damage than Unite due to larger debonding force.
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