Which whitening toothpaste with different contents is more effective on color and bond strength of enamel?

OBJECTIVE

To evaluate the effects of six whitening toothpastes with different whitening ingredients as follows: abrasives, polyphosphates, activated charcoal and hydrogen peroxide on the color, and shear bond strength (SBS) of enamel.

MATERIALS AND METHODS

Thirty-five extracted human molars were sectioned in mesiodistal direction, providing 70 enamel specimens and randomly divided into seven groups having different whitening ingredients (n = 10). After baseline color measurements, the specimens were brushed three times daily for the 30 s. At the end of 2 weeks, spectrophotometric readings were repeated, and color change parameters were calculated. Then, composite cylinders were built on the enamel surfaces and the specimens were subjected to SBS test. Failure modes were determined under a stereomicroscope (×10). One specimen from each group was examined with scanning electron microscope (SEM). The data were statistically analyzed using Kruskal-Wallis, Wilcoxon signed, one-way-ANOVA (p = 0.05).

RESULTS

Clinically acceptable color change was observed in all whitening toothpastes. There were no significant differences among the groups for Δa, ΔL, ΔE₀₀ , and ΔWI_D (p > 0.05). The differences among the groups were not significant regarding SBS and failure mode distributions (p > 0.05). SEM findings were in line with the SBS test and failure mode distribution results.

CONCLUSIONS

All the tested whitening toothpastes showed similar and clinically acceptable efficacy on the color change of the enamel and led to comparable SBS values.

CLINICAL SIGNIFICANCE

The tested whitening toothpastes had an acceptable whitening efficacy and did not have a negative effect on the bond strength to the enamel.

Clinical comparison of diode laser- and LED-activated tooth bleaching: 9-month follow-up

This study aims to evaluate the effect of diode laser- or LED-activated tooth bleaching on color change, tooth sensitivity(TS), temperature variation, and gingival irritation (GI) for 9 months. Thirty-five subjects having anterior teeth with a color of A2 or darker were enrolled in the study. In a split-mouth design, one side of each arch was activated by a diode laser (Epic X, Biolase), and the other side was activated by an LED (Radii Plus, SDI) in conjunction with a bleaching agent (35%, Whiteness HP). The color change was evaluated by subjective (VitaClassic/Vita3D Master Bleachguide) and objective (spectrophotometer, Vita Easyshade) methods for up to 9 months. TS and GI were assessed by visual analogue scale (VAS) and gingival index, respectively, at the same recall periods. During the bleaching, the temperature variation was also recorded using a thermocouple. Statistical analyses were performed (p < 0.05). In the color evaluation, no statistically significant difference was found between diode laser and LED (p > 0.05), except for the 6-month spectrophotometric assessment (ΔE₀₀, ΔE_ab), where higher values were obtained with the laser (p < 0.05). The temperature difference and maximum temperature with diode were found to be significantly higher than LED (p < 0.05). Higher values were obtained with LED when the mean temperatures were compared (p < 0.05). There was no difference between the two activation methods in terms of TS and GI at any of the recalls (p > 0.05). The bleaching activated either with diode laser or LED performed similar clinical performance in terms of effective color change, tooth sensitivity, and gingival irritation with minimum temperature variations.

Comparative evaluation of different adhesive strategies of a universal adhesive in class II bulk-fill restorations: A 48-month randomized controlled trial

OBJECTIVES

To compare the clinical performance of the universal adhesive used in etch-and-rinse (ER) and self-etch (SE) adhesive strategies for 48-month in class II bulk-fill restorations.

METHODS

A total of 84 class II bulk-fill resin composite (Tetric EvoCeram Bulk Fill) restorations were placed in 35 participants by one operator using the universal adhesive's (Adhese Universal VivaPen) etch-and-rinse or self-etch mode randomly. The restorations were evaluated by two calibrated examiners at baseline and after 6-, 12-, 24-, 36- and 48-month using modified USPHS criteria. The comparison of the two adhesive strategies for each evaluation criteria was performed with the chi-square test. The baseline scores were compared with those at the recalls using the Friedman and Cochran's Q-test (p < .05).

RESULTS

At 48-month, 74 restorations were evaluated in 30 participants (recall rate: 85.7%). Marginal discoloration was statistically more frequent in SE approach (p < .05), whereas no significant difference was observed between the two strategies in terms of marginal adaptation (p > .05). There were statistically significant differences between the baseline and 48-month recall in the SE group in terms of marginal adaptation and discoloration (p < .05). In ER group, significant differences were found between baseline and 48-month only for marginal adaptation (p < .05). None of the restorations showed post-operative sensitivity. Secondary caries was observed in one restoration from SE group.

CONCLUSIONS

The tested bulk-fill restorative exhibited better clinical performance only in terms of marginal discoloration when the universal adhesive was used with ER strategy.

CLINICAL RELEVANCE

Though ER approach of the tested universal adhesive appears to be advantageous in terms of marginal discoloration, both adhesive strategies had similar impact on the clinical success of bulk-fill resin restorations.