Bond strengths of ceramic brackets using different bonding techniques

A series of laboratory investigations was carried out to compare the shear-type bond strengths and site of bond failure of ceramic orthodontic brackets bonded to etched enamel. When light-cured composite resin was used as the luting agent, there was no reduction in bond strength when using 2.5 per cent nitric acid to etch the enamel, compared to 37 per cent phosphoric acid. The use of the two resin modified glass ionomer cements were found to give rise to significantly lower bond strengths than composite resin when used for placing ceramic brackets. Significantly less composite resin remained on the enamel surface following bracket removal in those samples etched with nitric acid.