Efficacy of bioactive materials in preventing Streptococcus mutans-induced caries on enamel and dentine.

The study investigated the ability of bioactive materials used to restore enamel and dentine specimens to prevent caries. Enamel (n = 50) and dentine (n = 50) specimens were obtained from bovine incisors, prepared, and randomly allocated to one of five groups according to the restorative treatment: alkasite without adhesive system; alkasite with adhesive system; high viscosity glass ionomer cement; resin composite; no restoration; negative control group. Specimens were restored, exposed to a thermal cycling aging protocol, sterilized, and exposed to a cariogenic challenge induced by Streptococcus mutans and then submitted to surface and subsurface microhardness tests and polarized light microscopy to verify the caries lesion development in enamel or dentine surrounding the restorative materials. Data were analyzed using one-way ANOVA. In enamel and dentine, glass ionomer cement, alkasite without and with adhesive system presented a lower percentage surface microhardness loss than resin composite and negative control. Enamel subsurface microhardness presented no statistically significant differences between glass ionomer cement, alkasite without and with adhesive system. Glass ionomer cement also did not present statistically significant differences from resin composite and the negative control. In dentine, glass ionomer cement showed the highest subsurface microhardness values. In conclusion, bioactive restorative materials provide greater protection to enamel and dentine against surface caries development than resin composite.

Surface smoothness of resin composites after polishing-A systematic review and network meta-analysis of in vitro studies.

A systematic review and network meta-analysis was performed to provide evidence for the best polishing protocol for different types of resin composites to minimize surface roughness. A search was performed in PubMed, Scopus, Web of Science, LILACS, BBO, EMBASE, and Cochrane Library on July 2, 2019 (updated in December, 2020). In vitro studies that included at least two systems for polishing resin composites and analyzed surface roughness were included. The risk of bias was evaluated. A random-effects Bayesian-mixed treatment comparison model was used to compare surface roughness in resin composites with the different types of polishers. Surface under the cumulative ranking curve (SUCRA) analysis was performed to rank the probability for the best polishing system. After removal of duplicates, title and abstract screening yielded 34 studies. Network meta-analysis was not possible for hybrid and microhybrid composites. SUCRA analysis showed that abrasive paper discs allowed greater surface smoothness for nanohybrid and nanofill composites to a probability of between 83% and 91.6%. Silicon carbide brush had a 78.2% probability of being the best system for microfill composites. The use of abrasive paper disc polishers showed a favorable result in nanofill and nanohybrid resin composites. Silicon carbide brush has a greater chance of promoting a smoother surface for microfill resin composites.

Effects of lesion size on the 30-month clinical performance of restorations with bulk fill and a regular nanofilled resin composite in noncarious cervical lesions.

OBJECTIVE: The aim of this double-blind, randomized trial was to evaluate the influence of the occlusogingival distance (OGD) in noncarious cervical lesions (NCCLs) on the clinical performance of a regular bulk-fill resin composite and a regular nanofilled resin composite. MATERIALS AND METHODS: One hundred and forty NCCLs in 77 participants were randomly divided into four groups (n = 35), according to OGD (1.5 mm ± 10% or 3 mm ± 10%) and resin composites (Filtek Bulk Fill Posterior [B] or Filtek Z350 XT [C]), namely: 1.5 mm-B, 1.5 mm-C, 3 mm-B, and 3 mm-C. The restorations were bonded using a two-step self-etch adhesive (Clearfil SE Bond), applied following the manufacturer's instructions. Restorations were polished 1 week after placement. Two experienced and calibrated examiners evaluated the restorations using modified US Public Health Service criteria at baseline (7 days) and after 6, 12, 18, 24, and 30 months. Statistical analyses were carried out using Kruskal-Wallis, Friedman's repeated measures analysis of variance, and the Wilcoxon signed rank test (α = 0.05). RESULTS: After 30 months, the recall rate was 94.2%. Eight restorations were lost (3 for 1.5 mm-C, 2 for 1.5 mm-B, 1 for 3 mm-C, and 2 for 3 mm-B). All groups resulted in a significantly worse marginal discoloration and surface texture at 30 months in comparison with the baseline (1 week). No significant difference was found for the other parameters. CONCLUSION: The restorations performed with both resin composites produced clinically acceptable restorations. The OGD of NCCLs did not influence the clinical performance of restorations. CLINICAL SIGNIFICANCE: The OGD of NCCLs did not have a significant effect on the clinical performance of a regular bulk-fill and nanofilled restorations. Both materials showed a very good performance on 30-month evaluation.

Do bioactive materials show greater retention rates in restoring permanent teeth than non-bioactive materials? A systematic review and network meta-analysis of randomized controlled trials.

OBJECTIVES: To answer the following research question: does the clinical evaluation of restorations on permanent teeth with bioactive materials show greater retention rates than those with non-bioactive materials? MATERIALS AND METHODS: A search strategy was used in the following databases: MEDLINE via PubMed, Scopus, Web of Science, LILACS, BBO, Embase, The Cochrane Library, and OpenGrey. Randomized controlled trials (RCTs), with a minimum of 2-year follow-up and evaluating at least one bioactive material in permanent teeth were included. Risk of bias was detected according to the Cochrane Collaboration tool for assessing the risk of bias (RoB 2.0), and network meta-analysis was performed using a random-effects Bayesian-mixed treatment comparison model. RESULTS: Twenty-seven studies were included. The success of the restorations was assessed using modified USPHS system in 24 studies and the FDI criteria in 3 studies. Network meta-analysis revealed three networks based on restoration preparations. Resin composites were ranked with higher SUCRA values, indicating a greater likelihood of being the preferred treatment for class I, II, and III restorations. In class V, resin-modified glass ionomer cement was ranked with the highest value. CONCLUSION: Bioactive restorative materials showed similar good clinical performance in terms of retention similarly to conventional resin composites. CLINICAL SIGNIFICANCE: The findings must be interpreted with caution because many RCT on restorative materials aim to verify the equivalence of new materials over the gold standard material rather than their superiority. The present systematic review also suggests that new RCT with longer follow-up periods are necessary.

Influence of different intraradicular chemical pretreatments on the bond strength of adhesive interface between dentine and fiber post cements: A systematic review and network meta-analysis.

Systematic review and network meta-analyses were performed to answer the question: Do intraradicular chemical pretreatments affect the bond strength of the adhesive interface between dentine and fiber post cements? A literature search was performed in PubMed, Scopus, Web of Science, LILACS, BBO, and Cochrane Library in October 2018 (updated September 2021). In vitro studies that compared the bond strength assessed by push-out tests following at least two dentine chemical treatments prior to fiber post cementation were included. Risk of bias was evaluated. A random-effects Bayesian-mixed treatment comparison model was used to compare push-out bond strength of different chemical pretreatments. SUCRA (surface area under the cumulative ranking) analysis was performed to rank the pretreatments. After removing duplicates and screening titles and abstracts, 61 studies remained. SUCRA analysis showed that the best bond strength values for self-etch, etch-and-rinse, and self-adhesive cements were ethyl acetate (SUCRA: 99.8%), low concentration NaOCl (SUCRA: 83.4%), and grape seed extract (SUCRA: 97.6%), respectively. According to the SUCRA rankings, ethanol was in a good position for all adhesive strategies (SUCRA: 78.6%). The use of chemical pretreatments in intraradicular dentine of endodontically treated teeth depends on the adhesive and cementation strategy. The pretreatment generally associated with the highest bond strength was ethanol.

Universal adhesive: the effect of different simulated pulpal pressure fluids and bonding modes to dentin.

The aim of this study was to evaluate the effect of SPP with either fetal bovine serum (FBS) or deionized water (DW) on the bond strength (µTBS) of a Universal adhesive to dentin, in both etch-and-rinse (ER) and self-etch (SE) modes. The kinematic viscosity (cSt) of FBS and DW was measured at 25 °C ± 0.1 ºC. Seventy-two sound human molars were sectioned and randomly divided into three groups according to the SPP conditions: (1) Control (0 cm H2O), (2) SPP (15 cm H2O) with FBS, (3) SPP (15 cm H2O) with DW. Each group was subdivided (n = 10) based on the bonding modes: ER (37% phosphoric acid + ScothBond Universal Adhesive) or SE (ScothBond Universal Adhesive). Samples were then submitted to µTBS. Data were analyzed by Student's t test, two-way ANOVA and Tukey tests (p < 0.05). The cSt results showed that DW (23.59 ± 0.39) had significantly higher values than FBS (22.33 ± 0.06). With regard to SPP, the control group (36.1 MPa) had significantly higher values of µTBS when compared to the SPP using FBS (31.06 MPa) and SPP with DW (26.55 MPa). According to ANOVA, the bonding modes and the interaction of simulated pulpal pressure (SPP) did not statistically influence the results (p < 0.05). The presence of SPP reduced the bond strength of Universal adhesive to dentin. DW during SPP had significantly reduced bonding values when compared to FBS. Bonding strategies were not affected by SPP when evaluated in a short period of time (24 h).

Sintering mode of a translucent Y-TZP: Effects on its biaxial flexure fatigue strength, surface morphology and translucency.

OBJECTIVE: This investigation evaluated the effect of two sintering modes of a translucent zirconia (Y-TZP) on its surface roughness, topography, phase-transformation (t → m), translucency and biaxial flexure fatigue strength. MATERIALS AND METHODS: To do so, 50 Y-TZP discs (Ø = 15 mm; thickness = 1.2 mm; IPS e.max ZirCAD LT) were prepared and divided into two groups: Standard mode (SM) and Fast mode (FM). Staircase fatigue testing was performed (piston-on-three balls set-up, ISO 6872:2015), as well as surface roughness, profilometry, scanning electron microscopy (SEM-FEG), energy dispersive X-ray spectroscopy (EDX), phase transformation (t → m) using X-ray diffraction analysis (XRD), translucency parameter analysis (TP and TP00 ) and fractography. RESULTS: The results showed no statistical significant differences for roughness parameters (p > 0.05, SM: Ra = 0.13 ± 0.02, Rz = 1.21 ± 0.26 and RSm = 24.91 ± 2.19; FM: Ra = 0.14 ± 0.03, Rz = 1.32 ± 0.25 and RSm = 24.68 ± 2.16) or flexural fatigue strength (SM: 512 (464-560) MPa; FM: 542 (472-611) MPa) between the groups. In addition, similarity in surface morphological features (SEM and profilometry), composition and phases (EDX and XRD) was observed between the firing protocols. Fractography showed that the failure origin occurred on the tensile side. Sintering mode did not affect the TP (F = 0.001, p = 0.97) and TP00 (F = 0.12, p = 0.72). CONCLUSIONS: Therefore, the fast-sintering mode is suggested as a viable alternative to the standard mode since it does not influence the evaluated surface morphology, microstructure, fatigue strength and translucency of a translucent monolithic zirconia. CLINICAL SIGNIFICANCE: The fast sintering mode is a viable alternative for zirconia without compromising its topography, microstructure, mechanical performance or translucency.

Effect of intraradicular fiber post on the fracture resistance of endodontically treated and restored anterior teeth: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: A fiber post is indicated when there is a significant loss of tooth structure and additional support for the restoration is needed. However, whether the use of a glass fiber post affects the fracture susceptibility of the restored anterior teeth is unknown. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate the fracture resistance of endodontically treated and restored anterior teeth and to answer the research question, "Does the use of a fiber post influence the fracture resistance of endodontically treated and restored anterior teeth compared with alternative restorative treatments?" MATERIAL AND METHODS: A search was performed in PubMed, Scopus, Web of Science, LILACS, BBO, Cochrane Library, and Embase databases without date and/or language restrictions (updated in July, 2020). In vitro studies comparing the fracture strength of endodontically treated and restored anterior teeth with and without fiber posts were included. The risk of bias was evaluated by using the previous meta-analyses of in vitro studies. The results were presented as standardized mean difference with a 95% confidence interval. Statistical heterogeneity of treatment effects between studies was assessed using the Cochran Q test and the I2 inconsistency test, and values greater than 50% were considered indicative of substantial heterogeneity. RESULTS: After the removal of duplicates and title and abstract screening, 31 studies remained. Seventeen were considered low risk of bias, 10 were medium risk of bias, and 4 were high risk of bias. Meta-analysis comparing control and experimental groups favored the use of a fiber post in endodontically treated teeth with some types of restoration to improve fracture resistance (standardized mean difference= 0.5 [0.08; 0.92]); a glass fiber post was also favored (standardized mean difference=0.92 [0.43; 1.42]); for veneer preparations and teeth with cervical cavities, a fiber post increases the fracture strength (standardized mean difference= 0.74 [0.01; 1.47]; 1.18 [0.35; 2.02], respectively). CONCLUSIONS: The use of glass fiber posts increases the fracture resistance of endodontically treated and restored teeth.

Bacterial levels and amount of endotoxins in carious dentin within reversible pulpitis scenarios.

OBJECTIVES: the objective of the present exploratory study was to determine bacterial diversity and endotoxin levels in deep carious lesions of teeth presenting symptoms of reversible pulpitis. MATERIALS AND METHODS: Twenty patients with deep carious lesions, reporting clinical symptomatology compatible with reversible pulpitis (n = 10) or not reporting clinical symptomatology (n = 10), were selected. Carious dentin samples were obtained with the aid of sterile and pyrogen-free spoon excavators and harvested in two steps: before and after infected dentin removal. Samples were collected for checkerboard and for kinetic chromogenic LAL assay for determination of microbial profile and quantitation of endotoxin, respectively. Data were analyzed by Mann Whitney for bacteria and two-way ANOVA for endotoxins (5%). RESULTS: No difference on the studied bacteria was detected between the superficial and deep dentin layers. Symptomatic teeth showed greater presence of Lactobacillus species, Capnocytophaga sputigena, and Leptotrichia buccalis. For the endotoxins, symptomatic teeth resulted in greater quantity of endotoxins (p = 0.047), being 4.13 log10 EU/mL/µg dentin and 3.45 log10 EU/mL/µg dentin, for symptomatic and asymptomatic teeth, respectively. Dentin collected in different areas presented similar number of endotoxins (p = 0.139). CONCLUSION: The amount of the studied bacteria does not seem to be related to reported symptomatology of deep carious lesions, while endotoxins quantity is greater in symptomatic scenarios, regardless of the harvesting area. CLINICAL RELEVANCE: The understanding of bacterial amount in reversible pulpitis is important to establish a clinical protocol of treatment.

Influence of glass fiber posts on the fracture susceptibility of endodontically treated maxillary anterior teeth with direct veneers: Preliminary results of a randomized clinical trial.

OBJECTIVE: The purpose of this randomized clinical trial was to evaluate the influence of glass fiber posts on fracture susceptibility of endodontically treated maxillary anterior teeth with direct veneers. MATERIALS AND METHODS: Fifty participants had 1 maxillary anterior tooth restored with a direct veneer. They were divided into 2 groups (n = 25) according to the use of intraradicular glass fiber posts. Clinical evaluation was performed at baseline, 6 and 12 months. The treatment success was determined by the absence of tooth fracture. If there was fracture, it was classified according to its extent. Fischer exact test was performed to analyze the criteria among the groups at each evaluation time. Friedman repeated analysis of variance assessed the difference in the performance of each group at three recall times (α = 0.5). RESULTS: For control group, at the 6-month follow-up, one tooth had suffered a catastrophic failure, which resulted in tooth extraction. Fisher statistical analysis showed no significant difference between the cumulative success rate of the groups for the 6 (P > .999) and the 12-month (P > .999) period. Friedman test showed no significant difference among the periods of evaluation (P > .999). CONCLUSIONS: Both groups had a similar success rate for maxillary anterior endodontically treated teeth with direct veneers after 12 months. CLINICAL IMPLICATIONS: Glass fiber post use does not influence the fracture susceptibility of maxillary anterior endodontically treated teeth with direct veneers in the short term.

A 2-year clinical evaluation of direct and semi-direct resin composite restorations in non-carious cervical lesions: a randomized clinical study.

OBJECTIVES: The purpose of this study was to evaluate the 2-year success of resin composite restorations in non-carious cervical lesions (NCCLs) using the direct or semi-direct techniques. MATERIALS AND METHODS: Thirty volunteers presenting with at least two NCCLs were included. Each participant received one restoration using the direct technique and the other using the semi-direct technique, totaling 60 restorations. Time for completing the treatment was computed. Assessments at baseline, 7 days, and 6, 12, and 24 months were performed using the modified United States Public Health Service criteria. Descriptive analysis was reported as a percentage of successful treatments. For inferential analysis, the Student t test was used to evaluate the differences between extension, depth, and time. The chi-square/Fisher tests were used to compare treatment success after each period (α = 0.05). The results were evaluated by using the Kaplan-Meier survival analysis. RESULTS: Differences were detected regarding mean ± standard deviation time, in which direct and semi-direct procedures were accomplished in 21.8 (± 14.5) and 35.3 (± 19.9) min, respectively. Of the 60 restorations placed, 7 failed in the direct group while 8 failed in the semi-direct group up to 2 years. No differences were detected between restorative protocols. The cumulative survival was 88.5% and 88.4% for the direct technique and semi-direct techniques after 24 months, respectively. CONCLUSION: The tested restorative protocols present similar results for NCCLs within the studied periods. CLINICAL RELEVANCE: The semi-direct technique exhibited clinical performance similar to direct technique for NCCL, demonstrating an alternative for restorations of these lesions.

Effect of staining and repeated firing on the surface and optical properties of lithium disilicate.

OBJECTIVE: Evaluate the effect of staining and repeated firings on color, translucency and surface proprieties of CAD/CAM lithium disilicate (LD). MATERIAL AND METHODS: One hundred eighty LD discs were made (ISO 6872) and distributed in different groups (n = 20): control (CO)-no treatment; single-step characterization (SC)-crystallization and staining fired together; and double step characterization (DC)-crystallization and then staining. The samples were submitted to two, four, or six firings, resulting in nine groups: COII, COIV, COVI, SCII, SCIV, SCVI, DCII, DCIV, and DCVI. The color and translucency were measured by a reflectance spectrophotometer. Surface roughness (Ra) and Vickers nano-hardness were also measured. ANOVA and Tukey statistical tests were used (α = .05). RESULTS: Only CO and DC demonstrated significant color alterations (ΔE00 > 1.8). SC and DC did not show changes in translucency by the number of firings (P > .05); however, for CO (P = .02) these values increased. Nano-hardness was similar in all groups (P > .05). Ra values indicated differences due to the type of characterization (SC presented the highest values) and number of firings (CO and DC groups) (P < .01). CONCLUSION: SC promoted color, translucency, and roughness stability after repeated firings. CLINICAL SIGNIFICANCE: The single characterization technic in CAD/CAM lithium disilicate presents good color, translucency, and hardness stability, which promote predictable results to monolithic restoration.

Nanofilled bis-acryl composite resin materials: Is it necessary to polish?

STATEMENT OF PROBLEM: Manufacturers of the recently introduced nanofilled bis-acryl composite resins no longer recommend polishing to produce interim restorations; however, whether this advice is appropriate is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of the type of interim resin material, polishing procedure, and artificial staining on surface roughness, gloss, and color. MATERIAL AND METHODS: Disk-shaped specimens were prepared from 1 unfilled acrylic resin (Duralay) and 3 bis-acryl composite resins (Structur 3-nanofilled, Systemp C&B-microhybrid, Proviplast-microhybrid). The specimens of each material were assigned to 2 subgroups (n=15): polished and unpolished. Surface roughness (Ra-µm), gloss (UB), and color (ΔE) were analyzed at baseline and after 14 days of artificial staining. Roughness and gloss data were separately analyzed by 3-way ANOVA and color by 2-way ANOVA, followed by the post hoc Tukey test (α=.05). RESULTS: The baseline roughness of all materials was significantly reduced by the polishing procedure, whereas the baseline gloss was increased (P<.001). Only the unpolished Proviplast had a significant increase in Ra values after aging. Structur 3 had higher gloss than Systemp C&B and Proviplast. The acrylic resin had the lowest color change after staining. CONCLUSIONS: The polishing procedure produced smother and glossier surfaces for all the materials tested. The nanofilled bis-acryl composite resin material had higher gloss than the microhybrid bis-acryls tested, but it was not different from the acrylic resin. The 14 days of artificial staining did not promote significant changes in Ra or gloss values, except for Ra in the unpolished Proviplast subgroup, indicating excellent performance of the materials. The acrylic resin had the highest color stability.

Influence of interim cements on the optical properties of interim restorations.

STATEMENT OF PROBLEM: Even if the appropriate resin shade is selected for an interim restoration, how the optical characteristics of the interim cement affect the esthetics of the interim restoration is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effects of interim cements on the optical properties of interim restorations. MATERIAL AND METHODS: Twenty dentin disks (6×1 mm) were obtained from the labial surface of bovine incisors. Disks of acrylic and bis-acrylic resins (n=20) with the same dimensions were prepared and cemented over the dentin using the following cements: Bifix Temp (resin-based; VOCO), ClearTemp LC (resin-based; Ultradent Products, Inc), Provicol (VOCO), TempCem NE (Coltène). The same dentin and resin disks were used for all cements. After cementation, the color difference (ΔE00), translucency parameter (TP), and fluorescence of the dentin/cement/resin combinations were compared with each other and with a control group (C), in which a transparent liquid (polyethylene glycol 400; LabSynth) was applied. Color and translucency were evaluated with a spectrophotometer (CM-2600; Konica Minolta) and fluorescence with a spectrofluorophotometer (RF-5301PC; Shimadzu). ΔE00 and TP data were analyzed using 2-way ANOVA. For fluorescence, 1-way ANOVA was used. The Tukey test was used for multiple comparisons (α=.05). RESULTS: ΔE00 values were significantly influenced by the interim material (P<.001) and the interim cement (P<.001). Bifix Temp showed the lowest significant ΔE00 values (P<.001). The highest ΔE00 values were observed for TempCem NE. No differences were observed between the interim resins with respect to TP (P=.318). The lowest translucency values were measured for TempCem NE, followed by Provicol, ClearTemp LC, Bifix Temp, and the control group (P<.001), with no significant differences among the interim resin-based cements. Among the cements, Bifix Temp and TempCem NE yielded fluorescence similar to that of the natural tooth for both interim resins. A similar result was found for bis-acrylic resin combined with Provicol. CONCLUSIONS: Cementation with interim resin-based cements resulted in better esthetics. However, the high fluorescence of the ClearTemp LC may reduce the esthetics of interim restorations in environments with predominantly UV light.

Bond Strength of Composite Resin Restoration Repair: Influence of Silane and Adhesive Systems.

AIM: The aim of this study is to evaluate the effect of silane (Si) application and different adhesive systems on the bond strength of composite resin repair. MATERIALS AND METHODS: One hundred composite truncated cone-shaped specimens were prepared and submitted to 5,000 thermal cycles to simulate existing restorations. Their top surfaces were airborne particle abraded with aluminum oxide, etched with phosphoric acid, and divided into two groups (n = 50) with or without Si application. Each group was divided into five subgroups (n = 10) according to the adhesive system applied: Solobond Plus Primer and Adhesive (SPA)-two-bottle, Solobond Plus adhesive (SA), Admira Bond (A)-one bottle, Futurabond DC (FDC)-self-etch, and Futurabond M (FM)-self-etch. New composite resin was applied over the bonded area. A control group was prepared to evaluate the cohesive strength of the composite resin. Specimens were submitted to tensile stress. Data were analyzed with two-way analysis of variance (ANOVA), and the Tukey and Dunnett tests. RESULTS: Si application reduced the bond strength of all adhesives (p = 0.001). Groups SA and SPA showed higher bond strengths in relation to other groups (p = 0.01). Groups FDC + Si, FM, FM + Si, and A + Si showed smaller mean bond strength values than that of the control group (p < 0.05). CONCLUSION: Previous Si application reduced bond strength values. The two-bottle adhesive showed better results than one-bottle or self-etching systems for composite resin repairs. CLINICAL SIGNIFICANCE: The kind of adhesive system applied for composite resin repairs has a great influence on bond strength values. The use of Si in this situation is not recommended.

Effects of artificial staining on bulk-filled resin composites.

PURPOSE: To evaluate the color stability of bulk-fill resin composites (RC) in comparison to conventional RC submitted to artificial staining. METHODS: 15 specimens of each RC were prepared. Five bulk-fill RC [X-tra Base (XB), Filtek Bulk-Fill Flowable (FBF), Admira Fusion X-tra (AD), Tetric N-Ceram Bulk-Fill (TB), and Filtek Bulk-Fill (FB) ], and two conventional RC [GrandioSO (GO) and Filtek Z350XT (FXT) ] were used. After preparation of the samples, the specimens were immersed in a staining broth for 5 weeks and repolished. The color change was assessed using a spectrophotometer. Data were analyzed using one-way ANOVA, Tukey's tests, and paired t-test. RESULTS: The bulk-fill flowable (XB and FBF) presented color change clinically acceptable (ΔE< 2.7) after staining. Among the bulk-fill regular resins, only AD presented clinically acceptable values (ΔE= 1.99). Regarding the conventional resins, GO presented a significantly lower color change than the other resins, but was not significantly different from AD. For all the resins, except AD, the repolishing procedures resulted in a significant decrease of color change. Tested resins did not present the same behavior under staining, despite their similarities. All the resins stained above the perceptibility threshold (ΔE> 1.2). After repolishing, the color change was reduced overall. CLINICAL SIGNIFICANCE: Color stability of resin composites was related to the properties of the resin material. The staining degree was related to the replacement of the restorations and repolishing contributes to the maintenance and longevity of these composites.

Effect of pH on whitening efficacy of 35% hydrogen peroxide and enamel microhardness.

OBJECTIVE: This study aimed to evaluate the effect of 35% hydrogen peroxide at different pH values and the degree of tooth staining on whitening efficacy and enamel microhardness. MATERIALS AND METHODS: 90 enamel-dentin specimens were obtained from bovine incisors. They were randomly divided into 2 groups (n = 45), 1 group was immersed in a staining broth for 14 days, and another group was not stained and kept in distilled water at 37°C. Twenty-four hours after the staining procedure, each group was distributed into 3 subgroups that were whitened by 35% hydrogen peroxide with different pH values (5, 7, and 8.4) for 30 minutes. The color was measured at baseline and 7 days after whitening. Microhardness was measured at baseline, immediate, 24 hours, and 1 month after the whitening procedure. Data were submitted to 2-way analysis of variance (ANOVA) and the Tukey test for multiple comparisons for color analysis. Repeated measures ANOVA and the Tukey test were used to analyze microhardness data. RESULTS: The color change of the stained groups (ΔE00 = 4.6) was significantly higher than that of the nonstained groups (ΔE00 = 3.7). Microhardness value decreased significantly immediately after whitening for all subgroups and did not return to initial values. For each measurement time, microhardness was not significantly different among subgroups with different pH values. CONCLUSIONS: Despite the effectiveness of 35% hydrogen peroxide, changes on gel pH did not affect the whitening efficacy, and the enamel was superficially demineralized, regardless of pH values. CLINICAL SIGNIFICANCE: Independently of the pH value of whitening gel, enamel undergoes superficial demineralization and with a reduction in superficial microhardness that does not return to the initial values. However, using hydrogen peroxide with different pH values does not alter the whitening effect.

Effect of Over-the-counter Whitening Products associated or Not with 10% Carbamide Peroxide on Color Change and Microhardness: in vitro Study.

Aim: The purpose of this in vitro study was to evaluate the color and microhardness of teeth subjected to different over-the-counter (OTC) whitening products in association or not with 10% carbamide peroxide (10% CP). Materials and methods: Enamel-dentin specimens (n = 210) were obtained from bovine incisors and stained. Half of the specimens were then subjected to daily cycles of staining (5 minutes), 10% CP bleaching (8 hours) in association with OTC products, and artificial saliva storage until complete 24 hours, for 2 weeks; the other half was subjected to daily cycles of staining, OTC treatment, and storage in artificial saliva for 12 weeks. The specimens were divided into 14 groups according to the OTC: CP-Water and Water (deionized water); CP-Listerine and Listerine (whitening mouth rinse); CP-Brushing and Brushing (mechanical brushing); CP-Colgate and Colgate (conventional toothpaste), CP-ColgateW and ColgateW, CP-OralBW and OralBW, and CP-CloseUpW and CloseUpW (whitening toothpaste). After staining and whitening, color and microhardness were measured. Data were submitted to analysis of variance (ANOVA) and the Tukey's test for multiple comparisons for color analysis and the paired t-test for microhardness analysis. Results: The CP and CloseUpW groups had the largest color change (AE00). The teeth treated with Colgate increased significantly in microhardness after whitening. Conclusion: The association of 10% CP with OTC whitening agents did not increase the whitening effect or microhardness. The OTC agents containing hydrogen peroxide and abrasives had a similar effect to one another but were not as effective as the CP groups and the subgroup brushed only with blue covarine toothpaste. Clinical significance: The current study provides information about the mechanism of OTC whitening products. None of the whitening agents evaluated damaged the enamel when used according to the manufacturers' instructions. The use of toothpaste containing hydrogen peroxide or abrasives cannot provide a whitening effect similar to at-home bleaching, and this does not improve with the association with 10% CP. However, toothpaste containing blue covarine has a satisfactory whitening effect immediately after brushing. Keywords: Laboratory research, Mouthwashes, Tooth bleaching, Toothpaste.

Effect of home-bleaching gels modified by calcium and/or fluoride and the application of nano-hydroxyapatite paste on in vitro enamel erosion susceptibility.

OBJECTIVE: This in vitro study compared the effect of bleaching agents modified by the addition of calcium and/or fluoride and the application of a nano-hydroxyapatite paste after bleaching, on the susceptibility of enamel to erosion. MATERIALS AND METHODS: Bovine enamel cylindrical samples (3 mm diameter) were assigned to six groups (n = 20 specimens/group) according to the bleaching agent: no bleaching (C-control), 7.5% hydrogen peroxide gel (HP), HP with 0.5% calcium gluconate (HP+Ca), HP with 0.2% sodium fluoride (HP+F), HP with calcium and fluoride (HP+Ca+F) and HP followed by the application of a nano-hydroxyapatite agent (HP+NanoP). The gels were applied on the enamel surface (1 h) followed by cyclic erosive challenges (Sprite Zero®-2 min), for 14 days. The paste was applied after bleaching for 5 min (HP+NanoP). The enamel surface alteration was measured by contact profilometry (µm) (after 7 and 14 days). RESULTS: C-control (mean ± SD: 2.29 ± 0.37 at 7 days/4.86 ± 0.72 at 14 days) showed significantly lower loss compared to the experimental groups. HP+Ca (3.34 ± 0.37/6.75 ± 1.09) and HP+F (4.49 ± 0.92/7.61 ± 0.90) presented significantly lower enamel loss than HP (4.18 ± 0.50/10.30 ± 1.58) only for 14 days and HP+Ca+F (4.92 ± 1.03/8.12 ± 1.52) showed values similar to the HP+F group. The HP+NanoP (5.51 ± 1.04/9.61 ± 1.21) resulted in enamel loss similar to the HP after 14 days. CONCLUSIONS: It was found that 7.5% hydrogen peroxide increased the susceptibility of enamel to erosion. The addition of calcium or fluoride to the bleaching gel reduced the erosion effect, while the nano-hydroxyapatite agent did not provide any protective effect.