Comparative evaluation of effect of chlorhexidine application on dentin bond strength with two different adhesives after ER, CR: YSGG phototherapy: an in vitro study.

This study aimed to assess the efficacy of phototherapy with an Er, Cr:YSGG laser on the bond strength of dentin using two different adhesive systems after chlorhexidine (CHX) application. Twenty-four non-carious human molar teeth were separated into three main groups: negative control Group A (Group A), CHX and phototherapy with an Er, Cr:YSGG laser (Group PC), and CHX with conventional diamond bur (no phototherapy) (Group C). These groups were divided into two subgroups based on adhesives: Clearfil Universal Quick Bond and Clearfil SE Bond. To evaluate the microtensile bond strength, the occlusal enamel surfaces of the teeth were removed with a low-speed, water-cooled diamond bur to expose hard dentin tissue. The teeth within Group PC were treated with Er, Cr:YSGG phototherapy. The surfaces were then disinfected with 0.2% chlorhexidine gluconate. Subgroups were applied according to the manufacturer's instructions using the adhesive systems mentioned above. Following adhesive application, the teeth were restored with composite resin. A microtensile bond strength test was performed on the test sticks obtained from the teeth using a universal test device. Data were analyzed using variance analysis (ANOVA) at a significance level of p < 0.05. Among all groups, the highest bond strength was achieved with Clearfil SE Bond with CHX + phototherapy (45.6 ± 4.2), while the lowest was achieved with Clearfil Universal Quick Bond without phototherapy (control group) (27.0 ± 6.7) (p < 0.05). Phototherapy with Er, Cr: YSGG following chlorhexidine application enhanced the bond strength of both the bond systems (p < 0.05).

Effectiveness and SEM-EDX analysis following bleaching with an experimental bleaching gel containing titanium dioxide and/or chitosan.

The aim of this study was to evaluate the bleaching effectiveness and mineral alterations following the use of experimental bleaching gels that included 6% hydrogen peroxide (HP), titanium dioxide (TiO2) and/or chitosan in comparison with the routinely used 35% HP bleaching gel. Thirty-six maxillary anterior teeth were divided into three groups according to bleaching agent as follows: Group 1: 6% HP + TiO2, Group 2: 6% HP + TiO2 + chitosan, Group 3: 35% HP. Tooth colour was measured with a spectrophotometer before bleaching and after sessions one and two on days 14 and 30, respectively. Colour changes were assessed with the CIEDE2000 and CIELab formulas. Mineral analysis was performed with a scanning electron microscopy-energy dispersive X-ray (SEM-EDX) device before and 14 days after application. The enamel surfaces of randomly selected samples from each group were analysed by SEM. Two-way ANOVA was used to compare differences between groups. All tested materials resulted in significantly increased bleaching compared to the initial colour values (p < 0.05). Group 3 showed significantly more whitening compared to the other groups after the first and second sessions (p < 0.05). However, Group 2 presented prolonged whitening efficiency and reached a bleaching level similar to the 35% HP treatment after 14 and 30 days. The results of the CIEDE2000 and CIELab formulas were found to be correlated (r > 0.6). The increases in Ca were similar in Groups 2 and 3 (p > 0.05) and were significantly higher than that in Group 1 (p < 0.05). p was similarly decreased among all groups (p > 0.05). The combination of 6% HP, chitosan and TiO2 appears to constitute a promising material for tooth whitening, showing good bleaching efficiency and acceptable mineral alterations.

Effects of different bleaching application time on tooth color and mineral alteration.

BACKGROUND: The effects of HP-based products upon dental enamel are inconclusive. PURPOSE: The purpose of this study was to evaluate the colour and mineral changes caused by the bleaching agent applications at different durations on the enamel surface. BASIC PROCEDURES: 60 caries-free lower central incisor extracted for periodontal reasons were standardized for enamel and dentin thickness after cone-beam computed tomography (CBCT) measurements in terms of mineral (n = 24) and colour change (n = 36). All teeth were divided into 3 groups according to different bleaching durations for colour (n = 12) and mineral change (n = 8) measurements. The samples for mineral change were examined with the -energy scattering X-ray (EDX, JSM-6390 LV, Jeol Inc., Japan) device before and 2 weeks after the application. For colour change, the measurement of the samples was performed with spectrophotometer device (VITA EasyShade 4.0, Germany). Opalescence Boost PF 40% (Ultradent Products, USA) was applied for 20 min (min) in Group 1, 40 min in Group 2 and 60 min in Group 3. In order to determine the efficacy of bleaching, colour measurements were repeated at 24 h, 7 and 14 days after the application. In the intragroup comparison, Friedman and Wilcoxon tests were used for non-normally distributions, while repeated variance analysis and paired t test were used for normally distributions in dependent variables. In the intergroup comparison, ANOVA and LSD tests were used for normally distributions, while Kruskal-Wallis and Dunn tests were used for non-normally distributions in independent variables. p < 0.05 was considered significant. MAIN FINDINGS: In the study, statistically significant difference was observed between all groups in terms of colour change at different measurement times (p < 0.05). The highest ΔE00 values were observed in Group 3 (ΔE003 = 8.37 ± 2.15); the lowest value was observed in Group 1 (ΔE001 = 4.74 ± 1.26). Ca values were similar increase among all groups (p > 0.05). The highest Ca values were observed in Group 3 (69.91 ± 5.34); the lowest value was observed in Group 2 (66.08 ± 1.50). P values were similar increase among all groups (p > 0.05). The lowest P values were observed in Group 3 (26.54 ± 5.92); the highest value was observed in Group 2 (29.86 ± 2.26). PRINCIPAL CONCLUSIONS: Effective whitening was achieved in all study groups. When the results are evaluated as versatile in terms of bleaching effectiveness and mineral change, the most ideal bleaching duration was determined as 40 min (Group 2).

Effects of a Newly Developed Experimental Bleaching Agent on Tooth Color and Shear Bond Strength of Composite Resins.

PURPOSE: To evaluate the bleaching efficacy and shear bond strength (SBS) of composite restorations performed immediately after bleaching with a newly developed experimental bleaching agent, including 6% hydrogen peroxide (HP), titanium dioxide (TiO2), and/or chitosan (CS). MATERIALS AND METHODS: We randomly divided 132 maxillary anterior teeth into 2 study groups, 60 teeth for color analysis and 72 teeth for the SBS test. For color analysis, teeth were divided into 5 subgroups. For SBS analysis, teeth were divided into 6 subgroups according to bleaching agent: group C (control): no bleaching; group 35HP: whiteness 35% HP; group 6HP: 6% HP; group HPC: 6% HP+CS; group HPT: 6% HP+TiO2; group HPTC: 6% HP+ TiO2+CS. The teeth were measured with a spectrophotometer before and 24 h after the bleaching, and calculated with the CIEDE2000 formula. SBS test was evaluated in composite restorations immediately after bleaching, using a universal testing machine. Statistical analysis was performed using ANOVA. RESULTS: The highest ∆E00 values were observed in group 35HP (4.2 ± 1.2); the lowest value was observed in group 6HP (1.7 ± 0.6) (p < 0.05). The values for groups HPC and HPT were similar to each other and significantly lower than the value for 35HP (p < 0.05 and p > 0.05, respectively). Group HPTC was similar to 35 HP (p > 0.05). For SBS, all groups except those containing chitosan showed significantly decreased bond strength compared to the control (p < 0.05), while groups HPC and HPTC had values similar to the control (p > 0.05). Group C (28.02 ± 6.81) had the highest value, while group 35HP (17.02 ± 7.79) had the lowest SBS value. CONCLUSION: With the newly developed agent, the bond strength immediately after bleaching was found to be similar to the control group. Its bleaching efficacy was similar to that of routinely used bleaching agents.