Nano-structured coatings in dentistry: surface analysis comparison of zinc oxide-coated stainless steel and zirconia crowns for pediatric use

Introduction
Nano-technology has enhanced dental materials, with zinc oxide nano-particles showing promise due to their antimicrobial properties. Zinc oxide (ZnO)-coated stainless steel and zirconia crowns are potential pediatric solutions, offering protection against bio-film formation and secondary caries.

Objective
This experimental, randomized in vitro study analyzed the surface characteristics of ZnO nano-particle-coated stainless steel and zirconia crowns.

Material and methods
Zinc oxide coatings were prepared using sol-gel method by dissolving zinc acetate in ethanol, followed by adding deionized water and citric acid. Crowns were immersed in this solution for 30 minu­tes, then air-dried and calcined at 500°C for 2 hours to form ZnO layer. Surface roughness was evaluated using atomic force mi-croscopy to quantify parameters, such as arithmetic roughness and root mean square roughness. Data analysis involved independent t-tests to assess differences in surface roughness between two investigated groups.

Results
The ZnO-coated stainless steel crowns showed significantly lower surface roughness (mean Sa, 0.1485 ± 0.003 µm) than ZnO-coated zirconia crowns (mean Sa, 7.189 ± 0.11861 µm), with a p-value < 0.001 indicating statisti-cal significance. Additional parameters, such as root the mean square roughness (Sq) and maximum peak-to-valley height (Sy), also favored stainless steel crowns, demonstrating a more uniform surface profile. These smoother surfaces may reduce bacterial adhesion, improving their suitability for pediatric dental appli-cations.

Conclusions
ZnO-coated stainless steel crowns offer smoother surfaces conducive to reduced plaque accumulation, sug-gesting a better application in pediatric dentistry. Future research should explore in vivo efficacy to validate clinical performance.