Shear Bond Strength Of Metal Brackets Bonded To Porcelain And Light-cured Composite Resin

With the increasing demand for adult orthodontic treatment, it may requires orthodontists to bond brackets directly to non-enamel prosthodontic materials. In this study, we bonded metal orthodontic brackets to two kinds of commonly-used prosthodontic materials: porcelain and light-cured composite resin with domestic adhesive and ordinary light-cured composite resin respectively and then the shear bond strength of the metal brackets, the integrity of the prosthodontic surface after debonding and the microscopic structure of the prosthodontic surface after surface treatment were examined.Part one Shear bond strength of metal brackets bonded to porcelainObjective To investigate the effects of different porcelain surface treatment method on the shear bond strength of metal brackets bonded to porcelain and examine whether the commonly-used Jing-Jin enamel adhesive and the ordinary light-cured composite resin are suitable for the porcelain-metal bracket bonding. Methods 80 porcelain facets were divided randomly into two groups according to different adhesive material that was used to bond metal brackets: (1) Jing-Jin enamel adhesive. (2) light-cured composite resia Each group was further divided into 4 subgroups with 10 porcelain facets each according to different surface treatment method: (1) acid etching with 37% phosphoric acid (H3PO4) .(2) acid etching with 9.6% hydrofluoric acid (HF) .(3)deglazing by grinding.(4) silanatingafter 37% phosphoric etching. All specimens were stored in 37 water for 24 hours and then the shear bond strength and the porcelain fracture after debonding were determined. The porcelain surfaces after HF etching , H3PO4 etching and deglazing by grinding were examined by scanning electron microscopy respectively. Results the shear bond strengths in the HF etching groups, the deglazing groups and the silanating groups were much greater than that in the phosphoric etching groups. Adequate orthodontic bonding were achieved both when bonding with light-cured composite resin after deglazing by grinding and when bonding with either of these adhesives after HF etching or surface silanating. There were no differences in the rates of porcelain fractures among groups. Conclusion HF etching, deglazing by grinding and silanating after etching can all increase the shear bond strength between metal bracket and porcelain. The Jing-Jin enamel adhesive and ordinary light-cured composite resin both can be used to the metal bracket-porcelain bonding after a proper surface treatment.Part two Shear bond strength of metal brackets bonded to light-cured composite resinObjective To investigate the effects of different resin surface treatment method on the shear bond strength of metal brackets bonded to light-cured composite resin and examine whether the commonly-used Jing-Jin enamel adhesive and the ordinary light-cured composite resin are suitable for the resin-metal bracket bonding. Methods 60 resin facets were divided randomly into two groups according to different adhesive material that was used to bond metal brackets. (1) Jing-Jin enamel adhesive. (2) light-cured composite resin. Each group was further divided into 3 subgroups with 10 resin facets each according to different surface treatment method: (1) acid etching with 37% phosphoric acid (H3PO4). (2) roughening by grinding. (3) non-treatment control group. All specimens were stored in 37 waterfor 24 hours and then the shear bond strength and the resin fracture after debondmg were determined. The resin surfaces after H3PO4 etching and roughening by grinding were examined by scanning electron microscopy respectively. Results The mean shear bond strengths in the roughening groups was greater than those in the non-treatment groups and the phosphoric etching groups. The mean shear bond strength in the group of light-cured composite resin bonding after phosphoric etching was greater than that in the group of non-treatment Jing-Jin enamel adhesive bonding group. There were no differences among other groups. The rates of resin fracture w...