Abstract:

Objective　To investigate the influence of different porcelain surface treatment methods on the shear bond strength of metal brackets bonded to porcelain.Methods　80 porcelain facetswere divided randomly intotwo groups accordingto different adhesive material thatwas used to bond metal brackets. Adhesive materialwere Jing-Jin enamel adhesive and light-cured composite resin. Each group was further divided into 4 subgroups according to different surface treatment methods,which were acid etching with 37% phosphoric acid(H3PO4),acid etching with 9·6% hydrofluoric acid(HF),deglazing by grinding and silanating the porcelain surface.All specimenswere stored in 37℃waterfor24 hours and then the shear bond strength and the porcelain fracture after debonding was determined. The porcelain surfaces afterHF etching, H3PO4etching and deglazing by grindingwere 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(P<0·01). Adequate orthodontic bonding strength was achieved both when bonded with light-cured composite resin after deglazing by grinding and when bonded with either of these adhesives afterHF etching or surface silanating. There were no differences in the rates of porcelain fractures among groups (P>0·05).Conclusion　HF etching, deglazing by grinding and silanating can all increase the shear bond strength between metal bracket and porcelain. Surface silanating of porcelain is a better surface treatmentwhen metal brackets bonded to porcelain.

Key words: porcelain, metal bracket, bonding