Characterisation of tribochemically assisted bonding of composite resin to porcelain and metal

Objective: The fracture of bonded ceramic to metal restorations remains a problem in clinical dental practice. The use of resin based composites to repair such fractures is generally unsatisfactory. Tribochemical technology creates a surface layer of small silica particles fused to the surface substrate. Such a layer potentially improves adhesion of resin to both alloy and porcelain. Adhesion between two substrates is traditionally studied using shear or tensile bond strength tests. However, the highest stress at bond failure may not represent the real bonding characteristics correctly. An alternative method is to describe the bonding characteristics by determining the strain energy release rate for a given interface. This study compares the bonding characteristics of a resin to gold/porcelain interface using a tribochemical coating process with those of a control group using simple gritblasting. Methods: Pre-cracked specimens were subjected to load–unload cycles using a simple four point bending test and the resultant strain energy release rates were calculated. Results: Tribochemically pretreating the porcelain resulted in a significant increase in the resultant strain energy release rate from 42.72±3.65 J/m2 for the controls to 61.35±6.26 J/m2. Likewise there was a significant improvement in the strain energy release rate for the gold/composite interface from 27.31±3.00 J/m2 to 42.13±4.83 J/m2. Conclusions: Tribochemical technology offers significant potential advantages for clinical dental practice.