Elementary Research Of The Factors Affecting The Shear Bond Strength Of Metal Brackets To Porcelain Surfaces

Objectives: To investigate the influence of different porcelain surface treatment methods and Silane Coupling Agent (SCA) on the bond strength of metal mesh-backed brackets to porcelain and porcelain fracture rate.Methods:300 Ceramics specimen were fabricated into samples with round surface, then glazed and divided randomly into 5 groups according to five different treatment methods: (1) etching with 37% phosphoric acid (H₃PO₄) for 1 min,(2) etching with 9.6% hydrofluoric acid (HF) for 3min, (3) sandblasting with 50μm Al₂O₃ particles ,(4) deglazing by grinding,(5) left untreated. Each group was further divided into 2 experimental groups incording the surface treatment with silane or omission of silane treatment. Jing-Jin enamel adhesive and 3M Unite? adhesive were utilized to bond the bracket onto each sample. The extracted teeth served as a control group. All specimens were stored in 37℃ water for 24 hours then treated with 5℃-55℃ circled fatigue experiment. The shear bond strength was determined and the porcelain fracture rate after debonding was recorded.The results were statistically analyzed.Results: Before the treated with SCA,the shear bond strength of 9.6%HF group was 4.4193±1.4549MPa, grinded group was 1.1837±0.7143MPa, sandblasted group was 2.3020±0.6477Mpa,and there was a significan difference among the three groups (P<0.05) . After the treated with SCA, the shear bond strength of...