Biomechanical evaluation of bonding with glass ionomer cement

This study was designed to determine the bond strength of three commercially available glass ionomer cements when used to bond mesh-backed medium twin standard edgewise (.022" x .028") brackets to enamel surface. The bond strength of one composite resin was compared with those of the glass ionomer cements. Scanning electron microscopic study of the debonded enamel surface was carried out to evaluate the effects of the bonding agents on enamel. The teeth were bonded with all the materials according to manufacturers' specifications. Each specimen was embedded in Dental stone with the bonded facial surface exposed. A special bracket holder was used to hold the brackets precisely under the wings during debonding. An Instron universal testing machine was used to measure the force required for bond failure. To simulate oral conditions, the direction of pull was so designed that it included an element of torsional stress along with tensile force. The findings indicate that Ketac-cem and Fuji II Glass ionomer cements hae adequate bond strength for clinical use. The scanning electron photomicrographs revealed that the enamel was least affected and well preserved in the Glass ionomer cement group. Further investigation is required to test the bond strengths of Glass ionomer cements clinically.