Abstract Tooth whitening represents perhaps the most common aesthetic procedure in dentistry worldwide. The efficacy of bleaching depends on three aspects: bleaching agent, bleaching method, and tooth color. Objective: This in vivo study aimed to examine whitening effects on frontal teeth of the upper and lower jaws using an over-the-counter (OTC) non-hydrogen peroxide bleaching agent in comparison to a placebo after one single use. Material and methods: Forty subjects (25 female; 15 male) participated in this double-blind randomized placebo-controlled trial. The subjects were randomly allocated to two groups (n=20). The test group received the OTC product (iWhite Instant) and the placebo group received an identically composed product except for the active agents. Each subject was treated with a prefilled tray containing iWhite Instant or the placebo for 20 minutes. The tooth shade of the front teeth (upper and lower jaws) was assessed before (E_0), immediately after (E_1) and 24 h after treatment (E_2), using a shade guide (VITA classical). Statistical testing was accomplished using the Mann-Whitney U test (p<0.001). The dropout rate was 0%. Results: There were no significant differences at E_0 between placebo and test groups regarding the tooth color. Differences in tooth color changes immediately after (ΔE1_0) and 24 h after treatment (ΔE2_0) were calculated for both groups. The mean values (standard deviations) of tooth color changes for ΔE1_0 were 2.26 (0.92) in the test group and 0.01 (0.21) in the placebo group. The color changes for ΔE2_0 showed mean values of 2.15 (1.10) in the test group and 0.07 (0.35) in the placebo group. For ΔE1_0 and ΔE2_0 significant differences were found between the groups. Conclusion: In this short-term study, the results showed that a non-hydrogen peroxide bleaching agent has significant whitening effects immediately and 24 h after a single-use treatment.

ABSTRACT Objective The purpose of this randomized, cross-over, in situ study was to determine the remineralization of demineralized dentin specimens after the application of a 10% fluoride (F-) or a 1% chlorhexidine–1% thymol (CHX–thymol) varnish. Material and Methods Twelve individuals without current caries activity wore removable appliances in the lower jaw for a period of four weeks. Each appliance contained four human demineralized dentin specimens fixed on the buccal aspects. The dentin specimens were obtained from the cervical regions of extracted human third molars. After demineralization, half the surface of each specimen was covered with a nail varnish to serve as the reference surface. The dentin specimens were randomly assigned to one of the three groups: F-, CHX–thymol, and control (no treatment). Before the first treatment period and between the others, there were washout periods of one week. After each treatment phase, the changes in mineral content (vol% µm) and the lesion depths (µm) of the dentin slabs were determined by transverse microradiography (TMR). Data analysis was accomplished by the Kruskal-Wallis test and the Mann-Whitney U test (p<0.05). Results The medians (25th/75th percentile) of integrated mineral loss were 312.70 (203.0-628.7) for chlorhexidine varnish, 309.5 (109.8-665.8) for fluoride varnish, and -346.9 (-128.7 - -596.0) for the control group. The medians (25th/75th percentile) of lesion depth were 13.6 (5.7-34.5) for chlorhexidine varnish, 16.5 (5.6-38.1) for fluoride varnish, and -14.2 (-4.5- -32.9) for the control group. Use of the 10% F- or 1% CHX–1% thymol varnishes resulted in significantly decreased mineral loss and lesion depth in dentin when compared with the control group. There were no statistically significant differences among the test groups. Conclusions Within the limitations of this study, the results suggest that the effect of the treatment of demineralized dentin with 10% F- or 1% CHX–1% thymol is better than without any treatment.