The effect of placement technique upon the compressive strength and porosity of a composite resin

This paper examines the effect of two placement techniques upon the compressive strength and level of porosity of specimens of a composite resin. Those specimens prepared by a condensation technique had a significantly lower mean compressive strength (P < 0·05) and value of Weibull modulus (P < 0·05) than specimens prepared using a smearing technique. No significant differences in the overall mean percentage area occupied by porosity and mean number of pores were demonstrated (P > 0·05) between the two placement techniques. Specimens prepared using the smearing technique, however, had significantly smaller mean maximum pore diameters (P < 0·05) than those prepared using the condensation technique. It is therefore desirable when placing composite resins to reduce to a minimum handling procedures that are likely to influence the levels of porosity within the material.