In-vitro Comparison of Effect of Two Moulding and Polishing Methods on the Surface Roughness of Heat Polymerized Resin

Acrylic resin is the most common material used for the fabrication of bases for prostheses including overdentures.A smooth surface is ideal for the maintenance of dentures and the prevention of bacterial colonization.Polishing materials used and the method of moulding are the few factors that affect surface roughness.Hence the present in vitro study was done to compare the effect of polishing materials and moulding methods on the surface roughness of dentures.120 specimens (50mm 3mm) were divided into two equal groups and fabricated by compression and injection moulding techniques.Each group was subdivided into 3 groups based on the polishing method viz: control (pumice), pumice with universal polishing paste and pumice with rouge based on the polishing protocols advocated.Determination of surface roughness was done with a profilometer.Statistical analysis was done with one-way ANOVA and Tukey HSD.The surface roughness ranged between 0.372 1.340 and 0.046 0.027.In both the moulding methods control group with pumice exhibited the greatest surface roughness in comparison with the other two groups and universal polishing paste produced the least.On comparing the two moulding methods the injection moulding method exhibited the least surface roughness.(p=0.0001).From the results of the study, it can be inferred that irrespective of the moulding method polishing using pumice and universal polishing paste would produce a smooth surface with the least roughness and could be implemented by all clinicians to bacterial colonisation and plaque formation in dentures.