Evaluation of Surface Roughness of Different Esthetic Restorative Materials after Immersion in Different Acidic Media

Abstract: Background: Dental erosion that resulted from increasing the acidity of oral conditions not only affects tooth substrates but also the performance of some esthetic restorations. Objective: The aim of the current study was to measure and evaluate the surface roughness of different tooth colored restorative materials (resin composites) after immersion for certain time in different acidic food and drinks. Material and method: Three types of composite restoration have been used in this study. The three types were of three main groups. Each group of twenty specimens (n= 20) were divided according to type of acidic media they were immersed in into five sub-groups (n=4). Different acidic beverages and drinks were used in this study include Coke Cola soft drink, orange juice, Pepsi soft drink, sports drink, and lemon juice. Immersion of specimens’ in previously mentioned acidic drinks were for 5 minutes then they have been immersed in distilled water to simulate to great extent what happened in oral cavity. These procedures repeated daily for 14 days. Surface roughness for specimens have been measured by a profilo-meter (Talysurf CLI 1000, Leicester, England) device before and after immersion. Data were collected, tabulated and analyzed using one-way ANOVA. Results: The assessment of surface roughness by one-way ANOVA and Tukey's post hoc tests showed significant differences for composite material types as well as an interaction between these parameters for each composite after immersion in different acidic beverages (P<.05). Conclusion: Within the limitation of this study, results revealed that composition of both resin composite and different acidic beverages and drinks play an important role in initiation and conduction of surface roughness at the outer surface of resin composite restoration.

Evaluation of the Surface Roughness of Resin Composites before and after Applying Different Bleaching Materials

Abstract: Background: Bleaching is a conservative treatment and has been shown to be both efficient and safe but the effects of bleaching on teeth and dental materials have been studied in several studies. Objective: The aim of the current study was to evaluate the surface roughness of resin composites before and after applying different bleaching materials. Material and method: Three types of resin composites were used in this in vitro study. Two types of bleaching techniques were used: in office and at home bleach. Sixteen specimens of each resin composite type were fabricated and used in this study. Surface roughness of the samples was measured using a profilometer (Talysurf CLI 1000, Leicester, England). The surface roughness measurements and data were statistically analyzed using the one-way ANOVA and Tukey's tests through SPSS version 21 (SPSS Inc. Chicago, IL, USA). The assessment of surface roughness was done using one-way ANOVA and Tukey's post hoc tests. P < 0.05 was considered statistically significant. Results: The assessment of surface roughness by one-way ANOVA and Tukey's post hoc tests showed significant differences for composite material types as well as an interaction between these parameters for each tested bleaching gels (P<.05). Conclusion: The composition of both resin composite and bleaching material play an important role in initiation and conduction of surface roughness at the outer surface of resin composite restoration.

Effect of post-irradiation polymerization on selected mechanical properties of six direct resins

This study evaluated the post-irradiation mechanical property development of six resin composite-based restorative materials from the same manufacturer starting at 1 h post irradiation, followed by 24 h, 1 week, and 1 month after fabrication. Samples were stored in 0.2M phosphate buffered saline until testing. Flexural strength, flexural modulus, flexural toughness, modulus of resiliency, fracture toughness, and surface microhardness were performed at each time interval. Mean data was analyzed by Kruskal Wallis and Dunn's post hoc testing at a 95% level of confidence (α=0.05). Results were material specific but overall, all resin composite material mechanical properties were found to be immature at 1 h after polymerization as compared to that observed at 24 h. It may be prudent that clinicians advise patients, especially those receiving complex posterior composite restorations, to guard against overly stressing these restorations during the first 24 h.

Effects of 16% Carbamide Peroxide Bleaching on the Surface Properties of Glazed Glassy Matrix Ceramics

Objective

To determine the influence of the home bleaching agent, Opalescence PF, on the surface roughness and microhardness of glazed glassy matrix CAD-CAM ceramics. Materials and Methods. The 28 sintered leucite- and lithium disilicate-reinforced ceramic specimens (IPS Empress CAD and IPS e.max CAD) were divided into control and bleached groups. The home bleaching agent was applied to specimens of bleached groups for 7 days. The surface roughness and microhardness of all specimens were measured. A scanning electron microscope was used to evaluate the surface properties. The data were statistically analyzed by two-way ANOVA.

Results

The control e.max CAD showed the lowest surface roughness values. For both Empress and e.max CAD, surface roughness was significantly higher for the bleached group (p < 0.05). No significant differences in microhardness were observed.

Conclusions

According to our study, patients should be careful when using home bleaching agents because whitening agents can affect the mechanical properties of full ceramic restorations like e.max CAD and Empress CAD. Ceramic polishing may be required in clinical situations where ceramic restorations are accidentally exposed to bleaching gels.

Hydrogen peroxide bleaching induces changes in the physical properties of dental restorative materials: Effects of study protocols

OBJECTIVE

The purpose of this study was to evaluate the influence of study protocols on the effects of bleaching on the surface roughness, substance loss, flexural strength (FS), flexural modulus (FM), Weibull parameters, and color of 7 restorative materials.

MATERIALS AND METHODS

The test materials included 4 composite resins, 1 glass-ionomer cement, 1 dental ceramic, and 1 polyacid-modified composite. The specimens were randomly divided into 4 groups (n = 20) according to different study protocols: a bleaching group at 25°C (group 25B), a bleaching group at 37°C (group 37B), a control group at 25°C (group 25C), and a control group at 37°C (group 37C). The specimens in the bleaching group were treated with 40% hydrogen peroxide for 80 min at the respective environmental temperatures. The surface roughness, substance loss, FS, FM, and color of the specimens were measured before and after treatment. FS data were also subjected to Weibull analysis, which was used to estimate of the Weibull modulus (m) and the characteristic strength (σ₀ ).

RESULTS

Surface roughness increased and significant color changes were observed for all tested specimens after bleaching treatment, except for the ceramic. After bleaching at 37°C, the polyacid-modified composite showed significantly reduced FS, FM, m, and σ₀ values in comparison to the control specimens stored at 37°C in whole saliva. Significant differences were also found between the 37B and 25B polyacid-modified composite groups in terms of surface roughness, FS, m, σ₀ , and color changes.

CONCLUSIONS

Varying effects of bleaching on the physical properties of dental restorative materials were observed, and the influences of the study protocols on bleaching effects were found to be material-dependent.

CLINICAL SIGNIFICANCE

The influence of study protocols on the effects of bleaching on the surface roughness, flexural properties, and color of dental restorative materials are material-dependent and should be considered when evaluating the effects of bleaching on dental restorative materials.

Influence of Restoration Type on the Cytotoxicity of a 35% Hydrogen Peroxide Bleaching Gel

OBJECTIVES

The tooth/restoration interface may act as a pathway for hydrogen peroxide (H2O2) diffusion into the pulp chamber. Therefore, the influence of resin-modified glass ionomer cement (RMGIC) and resin composite simulated restorations on the cytotoxicity of an in-office bleaching gel was assessed in vitro.

MATERIALS AND METHODS

Cavities in enamel/dentin discs restored with RMGIC Vitremer (3M ESPE) or Single Bond/Filtek Z350 (3M ESPE) resin composite (RC) were subjected or not subjected to hydrolytic degradation (HD). A 35%-H2O2 bleaching gel was applied to simulated restored and nonrestored enamel surfaces, and culture medium in contact with the dentin substrate (extract) was collected and applied to MDPC-23 cells. Nonrestored discs subjected or not subjected to bleaching were used as positive and negative controls, respectively. Cell viability, oxidative stress, interleukin (IL)-1β expression, alkaline phosphatase (ALP) activity, and mineralized nodule deposition were evaluated. The H2O2 in the extracts was quantified. Data were subjected to statistical analysis.

RESULTS

Higher oxidative stress associated with reduced cell viability, ALP activity, and mineralized nodule deposition was observed for all bleached groups compared with the negative control group. The RMGIC/HD group, which presented the highest H2O2 diffusion, had the lowest values of cell viability, ALP activity, and mineralized nodule deposition, as well as significantly increased IL-1β expression.

CONCLUSIONS

Dental cavities restored with the RMGIC subjected to hydrolytic degradation allowed for more intense diffusion of H2O2 into the pulp chamber, intensifying the toxicity of a 35%-H2O2 bleaching gel to pulp cells.

Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents

OBJECTIVE

This in vitro study evaluated the influence of two 10% carbamide peroxide bleaching agents - a commercial product (Opalescence PF; Ultradent Products, Inc.) and a bleaching agent prepared in a compounding pharmacy - on the chemical degradation of a light-activated composite resin by determining its release of ions before and after exposure to the agents.

MATERIAL AND METHODS

Thirty composite resin (Filtek Z250; 3M/ESPE) samples were divided into three groups: group I (exposed to Opalescence PF commercial bleaching agent), group II (exposed to a compounded bleaching agent) and group III (control - Milli-Q water). After 14 days of exposure, with a protocol of 8 h of daily exposure to the bleaching agents and 16 h of immersion in Milli-Q water, the analysis of ion release was carried out using a HP 8453 spectrophotometer. The values were analyzed statistically by ANOVA, Tukey's test and the paired t-tests. The significance level was set at 5%.

RESULTS

After 14 days of the experiment, statistically significant difference was found between group II and groups I and III, with greater ion release from the composite resin in group II.

CONCLUSIONS

The compounded bleaching agent had a more aggressive effect on the composite resin after 14 days of exposure than the commercial product and the control (no bleaching).

Effect of Bleaching on Microhardness of Esthetic Restorative Materials

High-concentration carbamide peroxide containing home bleaching may cause a varying influence on the microhardness of esthetic restorative materials.