The effects of nano Tio2 coating on self-cleaning and antibacterial efficacy of dental mirror

Surface coating of dental mirrors using nanotechnology has been done to render them self-cleaning properties. Nano-scaled titanium dioxide particles (TiO2)show antimicrobial properties when exposed to ultra-violet (UV) light. The aim of this study was to evaluate the effect of surface coating of dental mirrors with nano titanium dioxide on their self-cleaning (from dentists’ perspective) and antibacterial properties against Streptococcus mutans and Staphylococcus aureus. In this laboratory study, nanostructured titanium dioxide films were used for surface coating of half the understudy dental mirrors using sol-gel dip coating technique. To assess the self-cleaning property, 45 conventional and 45 nano TiO2 coated mirrors were coded. The two types of dental mirrors were compared by dentists during cavity preparation with a high speed hand piece and the related questionnaire was filled out. The opinions of 9 clinicians each comparing the dental mirrors on 5 patients were collected. For antimicrobial testing, a 0.5 McFarland standard of microbial suspension and 100 times dilution of the solution were prepared of the two understudy microorganisms; 50 μldrop of each dilute was transferred to the center of each dental mirror in the two groups. Dental mirrors were exposed to UV light for 30, 60, 90 and 120 min (3 mirrors in each group for each time period) and then immersed in 5ml of distilled water. Next, 50μl of the mentioned solution was cultured on blood agar culture medium. Number of colonies was counted after 24h. T-test with a significance level of 0.01 was used for microbial evaluation. Normal distribution tests (NPAR tests) were used for the assessment of improved vision and Friedman test was applied for comparison of the two groups. No statistically significant difference was found between the two groups in terms of antibacterial properties against S. mutans and S. aureus (P>0.05). No significant difference existed between the two types of mirrors in terms of clinical vision improvement from the dentists’ perspectives (P>0.05). Nano TiO2 coated mirrors did not have any superiority over the conventional types in terms of self-cleaning or antimicrobial properties.