SHEAR BOND STRENGTHS PRODUCED BY COMPOSITE AND COMPOMER LIGHT-CURED ORTHODONTIC ADHESIVES

Objectives: To test the shear bond strengths obtained when orthodontic brackets were bonded ex vivo using a composite resin and a compomer o rthodontic adhesive. Methods: Specimens were tested in a special jig m ade to fit an Instron testing machine. After debonding, the adhesive r emaining on bracket bases and enamel surfaces was mapped. Results: Bon d strengths ranged from 8 to 23 MPa with the composite resin producing higher strengths than the compomer for similar combinations of variab les. Bond strength was increased by longer curing and a longer debond interval and was higher for brackets with mesh bases than undercut bas es. More compomer remained on the enamel surface after debonding than did the composite resin. Conclusion: The compomer produced bond streng ths within the range considered to be clinically acceptable in other s tudies. If it was clinically successful as an orthodontic adhesive a c ompomer would confer the advantage that fluoride release would help to minimize the onset of early caries around bonded brackets. (C) 1997 E lsevier Science Ltd.