The effect of whitening toothpastes on tooth color andsurface roughness

Objective: The aim of this in vitro study is to evaluate the effect of toothpastes with different whitening mechanisms on the color change and surface roughness of human teeth. Materials and Methods: Forty caries-free human maxillary incisor teeth extracted for periodontal reasons were used. Using a precise cutting device under water cooling, each tooth was divided into two parts(crown and root) at the cementoenamel junction. The crown portions were embedded in self-curing cold acrylic in 3 cm-diameter silicone molds, with the vestibular surfaces facing downwards. The samples underwent minimal tissue-loss polishing with silicon carbide papers and were stored in distilled water for 24 hours prior to the staining process. All samples were immersed in a room-temperature solution containing soluble coffee for six days. After staining, the samples were washed with distilled water and randomly divided into five groups (n=8). Group I: Distilled water, control group; Group II: ROCS Sensation Whitening (RSW); Group III: Signal White Now Gold (SWN); Group IV: Colgate Optic White Charcoal (COW); Group V: Opalescence Whitening (OW). Color and surface roughness measurements were taken before and after the brushing period. Color measurements were conducted using the VITA Easyshade Advance 4.0 (VITA Zahnfabrik, Bad Sackingen, Germany) spectrophotometer, and surface roughness was assessed using a mechanical profilometer (Surftest SJ-201, Mitutoyo, Tokyo, Japan). Data were analyzed using One-Way Analysis of Variance (ANOVA) and Tukey HSD Test (p = 0.05). Results: Color changes above the acceptable threshold (ΔE00 = 1.8) were observed in all groups. The control group, brushed only with distilled water, showed the least color change. The RSW group, containing bromelain enzyme, exhibited the highest ΔE00 value, followed by the COW group, though no statistically significant difference was found between the two (p>0.05). Surface roughness changes across all groups were similar, with no statistically significant difference (p>0.05). Conclusion: Different whitening toothpastes do not significantly alter the surface roughness of human tooth enamel stained with coffee compared to distilled water over time. While all toothpastes improved tooth color, whitening toothpaste containing bromelain enzyme was found to be an effective option for patient use. Keywords: Brushing, Color, Human tooth, Surface roughness, Whitening toothpaste