Does Bleaching Affect the Microleakage of Class II Restoration with Bulk-Fill Composite?

Introduction. The use of technology in bulk-fill composites (BCs) has reduced the stresses caused by polymerization shrinkage, debonding, microleakage, or posttreatment sensitivity in them. This study was conducted to determine whether bleaching affects the microleakage of class II restoration with bulk-fill material. Materials and Methods. This laboratory study was performed on 40 normal human premolars in 4 groups (n = 20). Class II cavities were prepared in mesial and distal surfaces of the teeth with dimensions of 2 × 2 × 4 mm. Then, based on the bleaching process by 20% carbamide peroxide gel and using two types of composites, the restored cavities were randomly divided into 4 groups: (1) CC without bleaching (CC group), (2) BC without bleaching (BC group), (3) CC with bleaching (CCB group), and (4) BC with bleaching (BCB group). Then, the samples were thermocycled for 1000 cycles at a temperature range of 5–55°C, and they were immersed in 0.6% alkaline fuchsine in order to penetrate into the pigment for 24 h. After cutting, the samples were placed under a stereomicroscope (40%) to determine microleakage. The data were analyzed using one-way analysis of variance (ANOVA), and a p value <0.05 was considered as statistically significant. Results. Microleakage was determined in the CC group 0.97 ± 0.42 , BC group 1.08 ± 0.54 , CCB group 1.19 ± 0.37 , and BCB group 0.30 ± 0.47 . There were also no significant differences in the mean microleakage between the groups. No cases with zero microleakage (no microleakage) and grade 3 of microleakage (pigment penetration into the axial wall) were observed in the samples. Also, a two-by-two comparison of significant differences between CC and BC groups p = 0.89 , CC and CCB groups p = 0.45 , CC and BCB groups p = 0.11 , BC and CCB groups p = 0.87 , BC and BCB groups p = 0.41 , and CCB and BCB groups p = 0.86 showed that the difference was not statistically significant. Conclusion. Results showed no difference between microleakage of BC and CC with and without bleaching, and bleaching had the same effect on microleakage of these two types of composites.

Effect of Different Bleaching Methods on Optical Behaviors of CAD/CAM Ceramics

Background: The present study aimed to survey the influence of two different bleaching techniques on changes of color, translucency, and whiteness of the four CAD/CAM materials. Methods: The monolithic blocks of Vita Suprinity, Vita Enamic, IPS e.max CAD, and Katana Zirconia were sectioned to discs with thickness of 2 mm (n=30 / each group). Samples from each type of ceramic were assigned to three subgroups: 1) the 40% hydrogen peroxide for 20 minutes; 2) the 16% carbamide peroxide for three hours/day for 2 weeks; and 3) the control. Then CIELab coordinates of each sample were evaluated before and after the intervention by a spectrophotometer. Final color change (ΔE), Whiteness (ΔWI D), and Translucency Parameter (ΔTP) were calculated. Two-way ANOVA test was adopted to analyze the data (α=0.05). Results: Type of ceramic, bleaching subgroups, and interaction between them had a statistically significant influence on mean values of ΔE, ΔWID. The influence of bleaching subgroup on the mean value of ΔTP was also significant (P<0.001). Conclusions: Carbamide peroxide 16% for three hours/day and for two weeks caused the most considerable changes in final color, whiteness, and translucency of the all tested CAD/CAM materials. Maximum color change and whiteness were detected in the Vita Enamic, which were clinically unacceptable.

A Radical-Free Approach to Teeth Whitening

Background: Traditional bleaching agents based on hydrogen peroxide (HP) or carbamide peroxide (CP) have adverse soft and hard tissue effects. Objectives: This study tested a novel formulation of phthalimidoperoxycaproic acid (PAP) with additives to optimise its safety and effectiveness. Methods: A novel gel (PAP+) was formulated. Laboratory studies assessed effects of six 10-minute exposures to PAP+ vs. commercial CP and HP gels, using surface profilometry and microhardness. The effectiveness of PAP+ in vitro against complex polyphenol stains on enamel was compared to 6% HP. Results: Unlike HP gels, PAP+ gel did not erode enamel. Unlike both CP and HP gels, PAP+ gel did not reduce the surface microhardness of enamel. PAP+ gel on used on polyphenol stains was superior to 6% HP. In this model, six repeated 10-minute treatments with PAP+ gel could improve the shade by approximately eight VITA® Bleachedguide shades. Conclusions: These laboratory results support the safety and effectiveness of this new PAP formula and its use as an alternative to CP and HP with superior safety and effectiveness.

Direct Radiotherapy-Induced Effects on Dental Hard Tissue in Combination With Bleaching Procedure

Introduction: The aim of this study was to evaluate the effects of radiation and tooth bleaching on the physical and morphological properties of enamel and dentin on permanent teeth.Materials and Methods: Eighty fresh, non-carious third molars were used in this study. Before cutting the crown in half, the teeth samples were randomly allocated to treatment and control groups by using a lottery method. The first group (n = 20) underwent standard radiation protocol (2 Gy/fraction/day, 5 days/week) with bleaching treatment afterward using 16% carbamide peroxide gel, the second group (n = 20) underwent standard radiation protocol with afterward bleaching treatment using 38% hydrogen peroxide, the third group (n = 20) underwent a short, one strong, experimental dose of 70 Gy with afterward bleaching treatment using 16% carbamide peroxide gel, and the fourth group (n = 20) underwent one strong, experimental dose of 70 Gy with afterward bleaching treatment using 38% hydrogen peroxide gel. Groups 5–8 (n = 20) served as control as they underwent only bleaching treatment. Vickers microhardness and surface roughness were performed before (initial) and after irradiation and before bleaching or after only bleaching. The effects of irradiation and bleaching on microhardness (or roughness) of enamel and dentin were analyzed in the repeated-measures ANOVA model.Results: Enamel microhardness after experimental single 70-Gy irradiation or after standard radiation protocol and bleaching with 16 or 38% gel was not statistically significant from microhardness in the control group (p &gt; 0.05). There was a statistically significantly greater reduction in the average microhardness of enamel and dentin during bleaching with 38% gel compared to 16% for both radiation protocols (p &lt; 0.001). After experimental 70-Gy irradiation and bleaching, a 16% statistically significant increase in surface roughness was found for enamel (p = 0.006) and dentin (p = 0.018), while this was not recorded for 38% gel. There was a statistically significantly greater increase in the average roughness of enamel and dentin during bleaching with 38% gel compared to 16% (p &lt; 0.001) for both radiation protocols.Conclusions: Directly induced radiation leads to potential damage of hard dental tissues, which can be further damaged by additional bleaching. If teeth whitening is necessary after irradiation, it is suggested to use lower concentrations of whitening gels.

Case Reports of Enamel Microabrasion Associated with At-home Dental Bleaching After Orthodontic Bracket Removal

SUMMARY Adequate removal of residual bonded materials from the enamel surface after orthodontic bracket debonding is critical, since any remaining composite may compromise enamel surface morphology and esthetics. The following clinical case reports present the association of at-home dental bleaching using 10% carbamide peroxide and the removal of residual bonded material using a super fine, tapered diamond bur followed by the use of an enamel microabrasion product after orthodontic bracket debonding. The proposed treatment considerably improved the esthetics and successfully removed the grooves created during the removal of the bonding composite, resulting in a smooth enamel surface.