Twenty-four hour and six month evaluation of porcelain surface preparation and orthodontic bond strength
Jarotski, Todd J.
Bonding orthodontic attachments to porcelain can be challenging. The purpose of this study was to investigate the 24 hour and 6 month shear bond strengths of orthodontic buttons bonded to porcelain using six different surface preparations: (1) Pumice polish for 5 seconds and 37% phosphoric acid etch with or (2) without the use of a silane primer, (3) microabrasion with 90[mu] aluminum oxide for 5 seconds with or (4) without the use of a silane primer and (5) hydrofluoric acid etch for 120 seconds with or (6) without the use of a silane primer. For each of the six experimental surface treatment groups, two orthodontic buttons were bonded to each of ten flat porcelain surfaces. The bonded test assemblies were shear tested to failure after 24 hour and 6 month storage at 37C and 100% R.H. The shear bond strengths were calculated and analysed using the single ANOVA and Tukey's multiple comparison test. When compared to 24 hour results, the samples treated with microabrasion and silane, hydrofluoric etch and silane and hydrofluoric etch alone underwent no significant reduction in mean bond strength (p > 0.05). The samples treated with microabrasion and silane, microabrasion alone and pumice polish alone underwent significant reductions in mean bond strength (p < 0.05), with dramatic reductions being seen in the microabrasion alone and pumice polish alone test groups. Samples treated with microabrasion and silane and hydrofluoric acid etch and silane experienced unacceptably high incidences of porcelain fracture. Caution is advised when extrapolating the in vitro results to the clinical situation.