Comparative evaluation of surface roughness of posterior primary zirconia crowns

Aims: To compare the surface roughness of four commercially available posterior zirconia crowns on the occlusal surface and occlusal edge (buccal cusps) of first and second primary molars crowns. Methods: Surface roughness of 40 posterior primary zirconia crowns was measured using a mechanical stylus profilometer. Ten mandibular right molar crowns, consisting of five first primary molar and five second primary molar crowns from four brands—Cheng, Sprig EZCrowns, NuSmile and Kinder Krowns were selected. Mean roughness, Ra and mean roughness depth, Rz was measured for all crowns on two selected surfaces, occlusal surface and buccal cusp tips. Data was evaluated by one way analysis of variance and Tukey’s honestly significant difference test at 0.05 level of significance. Results: Statistically significant differences were observed in the mean Ra and Rz values at both selected surfaces among four prefabricated paedodontic zirconia crowns. Kinder Krowns had higher Ra and Rz values compared to Cheng, Sprig EZCrowns and NuSmile. Roughness profile of Kinder Krowns also showed higher vertical scale values co-relating with higher Ra and Rz scores, irrespective of the measurements taken on relatively flat surfaces (occlusal edge) or deeper surface (occlusal pits and fissures). Conclusions: Mechanically polished posterior primary zirconia crowns had a smoother surface profile than the combined polished-glazed primary zirconia crowns. Cheng Crowns had the lowest mean Ra and Rz values although not statistically significant from Sprig EZCrowns and Nu Smile. Kinder Krowns had the highest mean Ra and Rz scores than other crown groups.