Titanium abutment background masking using highly opaque cements for implant prosthetics.

PURPOSE: To evaluate the capacity of highly opaque cements on masking titanium abutment background. METHODS: Dentin and titanium specimens were used to simulate respectively, a natural dental background and an implant abutment. To simulate the full-crowns, Y-TZP zirconia (ZC), lithium disilicate (LD), and resin composite (RC) blocks were used. The titanium specimens were divided into six cementation groups (n=10): two regular cements (BQM and RX); three opaque cements (MHA; VA and BHA); and a clear liquid (CL). The masking capacity of each cement was calculated as the color difference between the color of the crowns over dentin with clear liquid (reference) and the color of the crowns over the titanium with the different cements (ΔEab). Data were statistically analyzed using two-way ANOVA and Tukey test (α= 0.05). RESULTS: Significant differences (P= 0.0001) were observed for both factors, cement and crown, and for the interactions between them. The results of Tukey test for cement were: BHA-2.25(0.98), MHA-2.94 (1.03), VA-3.45 (1.67), BQM-9.55 (2.77), RX-9.88 (3.12), CL-10.41 (3.47). The cements BHA, MHA and VA showed significantly smaller means than BQM, RX and CL. The results for crown were: ZC-3.66 (2.37), LD-7.50 (4.08), RC-8.08 (4.67). The means for all crown materials were significantly different. Highly opaque cements were more efficient on background masking than regular cements. Zirconia promoted the higher color masking while the resin composite the lowest. CLINICAL SIGNIFICANCE: The use of a highly opaque cement can reduce the color interference of the titanium abutment background, favoring the esthetic outcome of metal-free cemented crowns.

Effect of a hydrogen peroxide bleaching agent with calcium and phosphorus-containing salts on enamel surface hardness and roughness.

PURPOSE: To evaluate whether adding calcium and phosphorus-containing salts to 35% hydrogen peroxide at saturation concentrations with respect to hydroxyapatite would reduce its deleterious effects on bleached enamel or affect bleaching efficacy. METHODS: The saturation concentrations of elemental calcium and phosphorus in a 35% hydrogen peroxide solution were determined after equilibration with powdered enamel. The solubility limit of the salts in 35% hydrogen peroxide was then experimentally determined. Polished bovine enamel-dentin specimens (n=120) with known baseline enamel Knoop microhardness (KHN), surface roughness (Ra), and color were bleached with hydrogen peroxide containing different concentrations of calcium and phosphorus-containing salts as follows: Negative Control - water without any addition; Positive Control - 35% hydrogen peroxide without any addition; 50% of Ca and P - hydrogen peroxide with calcium and phosphorus-containing salt additions of 50% of the saturation concentration; 100% of Ca and P - hydrogen peroxide with calcium and phosphorus-containing salt additions of 100% of the saturation concentration; Ca limit - hydrogen peroxide with addition of calcium-containing salt at the solubility limit, and P limit - hydrogen peroxide with addition of phosphate-containing salt at the solubility limit. The prepared bleaching solutions were applied on the surface of the specimens for 60 minutes. The microhardness and surface roughness were measured immediately after bleaching, and the color change (ΔE*00) was evaluated after 7 days. RESULTS: One-way ANOVA showed significant differences among the groups for all evaluations (P< 0.05). The groups saturated with elemental calcium and/or phosphorus with respect to hydroxyapatite did not show significant changes in microhardness and roughness in relation to the negative control, while the positive control without mineral supplementation and the 50% saturated group showed reduced microhardness and increased roughness. The addition of calcium and/or phosphorus-containing salts in sufficient concentrations to create a saturated hydrogen peroxide solution with respect to hydroxyapatite was able to completely prevent surface changes without affecting the bleaching effect. CLINICAL SIGNIFICANCE: The addition of ions at saturation concentrations or higher with respect to hydroxyapatite can prevent enamel demineralization without compromising the efficacy of bleaching gels.

Influence of Bleaching Gel Peroxide Concentration on Color and Penetration through the Tooth Structure.

AIM AND OBJECTIVE: The purpose of this study was to assess the effect of hydrogen peroxide concentration on the bleaching efficacy and penetration through the tooth structure. MATERIALS AND METHODS: One hundred enamel/dentin specimens with cylindrical shape were obtained from bovine incisors. The surfaces were polished and the size standardized. They were divided into five groups (n = 20), following the concentration of hydrogen peroxide in the bleaching gels: 20, 25, 30, 35, and 40% (w/w). The specimens were placed over artificial pulpal chambers containing acetate buffer solution and bleached for 30 minutes (three applications of 10 minutes each). Aliquots of the acetate solution were collected, and the peroxide concentration was measured by an analytic spectrophotometer. The color of the samples was analyzed using a colorimetric spectrophotometer at the baseline and 7 days after the bleaching procedure. The color difference was calculated using the ∆Eab formula. The data were analyzed by one-way ANOVA and Tukey's test (p <0.05). RESULTS: The peroxide concentrations of 20-30% showed smaller bleaching effect than the higher concentrations (p = 0.001). The peroxide penetration was significantly higher (p = 0.001) for the more concentrated gels (35 and 40%). CONCLUSION: The higher peroxide concentrations enhance the bleaching efficacy, but also increased the peroxide penetration through the tooth structure. CLINICAL SIGNIFICANCE: In-office bleaching gels with higher concentrations of hydrogen peroxide (35 and 40%) present superior whitening efficacy. Nevertheless, they might also intensify the negative biological effects on the pulpal tissue, since they exhibit increased penetration potential. How to cite this article: Torres CRG, Zanatta RF, Godoy MMM, et al. Influence of Bleaching Gel Peroxide Concentration on Color and Penetration through the Tooth Structure. J Contemp Dent Pract 2021;22(5):479-483.

Assessment of permeability of eroded dentin after the use of universal, self-etch, and conventional systems.

Dentin hypersensitivity is caused by increased dentinal permeability due to total or partial exposure of dentinal tubules, which in turn can be produced by alterations of dental structures or failure of restorative procedures. The purpose of this in vitro study was to evaluate the efficacy of the application of different kinds of adhesive systems to prevent dentin permeability before and after an erosive challenge. Fifty bovine dentin discs (6x1 mm) were prepared and the specimens were divided into 5 groups (n=10): (SB2) Single Bond 2, (SBU) Universal Single Bond, (CSB) Clearfil SE Bond, (SM) Scotchbond Multipurpose and (C) Control. Hydraulic conductance of dentin was recorded after adhesive application (HC-1) and after erosive challenge (HC-2). Dentin surface images of post-treatment and post-erosive challenge were obtained by scanning electron microscopy (SEM). Data were analyzed using Kruskal Wallis, Mann-Whitney with Bonferroni correction and Wilcoxon tests (p<0.05). Reduction in dentin permeability was observed with the application of adhesive systems (p<0.05). After the erosive challenge, dentin permeability increased for SBU and CSB (p<0.05), while SB2 and SM did not differ in HC-1 or HC-2 (p>0.05). The conventional, self-etching and universal adhesive systems reduce dentinal permeability by more than 80%, and dentin demineralization may contribute to the increased permeability of universal and self-etching systems.

Diversos pacientes apresentam hipersensibilidade dentária ou falha nos procedimentos restauradores, devido à exposição total ou parcial de túbulos dentinários. O objetivo deste estudo in vitro foi o de avaliar a influência da aplicação de diferentes tipos de sistemas adesivos na permeabilidade da dentina e após o desafio erosivo. Cinquenta discos de dentina bovina (6x1 mm) foram confeccionados e os espécimes foram divididos em 5 grupos (n = 10): (SB2) Single Bond 2, (SBU) Universal Single Bond, (CSB) Clearfil SE Bond, (SM) Scotchbond Multiuso e (C) Controle. A condutância hidráulica da dentina foi registrada após a aplicação do adesivo (HC-1) e após o desafio erosivo (HC-2). Imagens da superfície da dentina de pós-tratamento e pós-desafio erosivo foram obtidas por microscopia eletrônica de varredura (MEV). Os dados foram analisados pelos testes de Kruskal Wallis, Mann-Whitney com correção de Bonferroni e Wilcoxon (p <0,05). Redução da permeabilidade dentinária foi observada com a aplicação dos sistemas adesivos (p <0,05). Após o desafio erosivo, a permeabilidade dentinária aumentou para SBU e CSB (p <0,05), enquanto SB2 e SM não diferiram em HC-1 e HC-2 (p> 0,05). Os sistemas adesivos convencionais, autocondicionantes e universais reduzem a permeabilidade dentinária em mais de 80%, e a dentina desmineralizada pode gerar um aumento da permeabilidade dos sistemas adesivos universais e autocondicionantes.

Bulk-fill versus layering pure ormocer posterior restorations: A randomized split-mouth clinical trial.

PURPOSE: To evaluate the clinical performance of Class II restorations made with bulk-fill or layering pure ormocer materials, as well as the time necessary to fill the preparations. METHODS: After ethics approval, a randomized controlled split-mouth clinical trial was performed. 30 subjects were selected according to the inclusion/exclusion criteria, and two restorations were randomly performed in each first or second molar that presented caries, fracture, or cosmetic needs. One restoration was done with the bulk-fill material Admira Fusion x-tra, applied with increments up to 4 mm (intervention group), while the second was performed with the regular Admira Fusion, applied by a 2 mm layering technique (control group). The universal adhesive system Futurabond U was used for both groups. The subjects and examiners were blinded, and the examiners were previously calibrated. The restorations were evaluated according to FDI criteria, after 7 days, 6, 12 and 24 months, and the outcome was success rate based on esthetic, functional and biological properties. The time necessary for application of both materials into the preparations was also measured. RESULTS: After 24 months, 26 patients attended the recall and 52 restorations were evaluated. The Fisher's statistical analysis (α= 5%) showed non-significant differences between techniques for esthetic, biological and functional properties in all evaluations (P> 0.05). After 2 years, 96% of the subjects for both groups did not show any sign of post-operative sensitivity and 100% of the teeth were vital and without secondary caries. Around 70% of the restorations received score excellent for surface luster, more than 83% for surface staining and 63% for color match. In relation to marginal adaptation and marginal staining, more than 80% for the layering material and 63% for the bulk showed excellent scores. Only three restorations of the 60 performed showed small fractures, although not affecting the esthetics or function. The time for composite application was significantly shorter for the bulk material (P= 0.0454). After 24 months of intraoral service, the restorations made with both materials presented similar and excellent clinical performance for all parameters analyzed. The bulk-fill material required significantly less chair time to apply than the layering one, simplifying and accelerating the restorative technique. CLINICAL SIGNIFICANCE: The bulk-fill ormocer-based composite was an appropriate alternative to the conventional layering material, since similar clinical performance was observed after 2 years, with the advantage of shorter chair time, due to simplified operative procedures.

Hydrogen peroxide degradation of bleaching systems with different trays: Randomized clinical trial.

PURPOSE: This crossover study evaluated the hydrogen (HP) and carbamide (CP) peroxide degradation of bleaching gels in prefilled (PT) and customized trays (CT). METHODS: Volunteers were randomly allocated to treatments (n=10) : PT-HP/OGO (Opalescence GO-10%); CT-HP/WTC (White Class-10%) or CT-CP/OPF (Opalescence PF-10%). Gel samples were collected from the upper and lower trays in each period (baseline, 15, 30, 50 and 120 minutes). HP concentration was determined with the potassium permanganate titration method. Degradation was calculated based on initial concentration of gels. Repeated measures two-way ANOVA and Tukey's test (5%) were applied. RESULTS: Bleaching gels exhibited exponential degradation over time. In 30 minutes, no significant differences in degradation among them were detected (P= 0.13). After 2 hours, lower degradation of CT-CP/OPF (61.85±10.65), compared with hydrogen peroxide in PT and CT (71.55±8.24 and 78.69±9.33, respectively) was observed. The gels showed higher degradation rate in lower trays than in upper trays in all evaluated times. In general, the bleaching gels in lower trays degraded more than in upper trays. The carbamide peroxide gel presented lower degradation than hydrogen peroxide after 2 hours. The degradation of the 10% hydrogen peroxide gel used in prefilled trays was higher than the one in customized trays after 30 minutes, but after 120 minutes, the degradation rate was similar for both. CLINICAL SIGNIFICANCE: Bleaching gels degraded faster in lower arches than in upper arches. The degradation process was faster in the first 15 minutes of use and depended on the gel's composition, time of use, and tray position in the dental arches.

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.

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.

Does ErbiumiYttrium-Aluminum-Garnet Laser to Enamel improve the Performance of Etch-and-rinse and Universal Adhesives?

AIM: This study aims to evaluate the effect of erbium: Yttrium-aluminum-garnet (Er:YAG) laser irradiation on the enamel microshear bond strength (µSBS), followed by the utilization of etch-and-rinse and universal adhesive systems. MATERIALS AND METHODS: A total of 32 molars were sectioned in the mesiodistal direction producing 64 samples that were randomized into two groups (n = 32): single bond 2 (SB2) (etch-and-rinse system; 3M), SB universal (SBU) (universal etching system; The SB2 and SBU groups were then divided into two subgroups (n = 16): (i) enamel was irradiated with an Er:YAG laser (λ = 2.94 µm, 60 mJ, 10 Hz), and (ii) enamel served as a control. The samples were restored with TPH3 (Dentsply), stored in artificial saliva for 24 hours, and subjected to a micro-shear test. RESULTS: Kruskal-Wallis (p < 0.05) and Mann-Whitney U tests indicated no significant differences in uSBS between the groups, and the fractures were predominately at the resin-enamel interface. CONCLUSION: The previous irradiation of enamel with Er:YAG laser does not interfere with the performance of simplified two-step etch-and-rinse and universal adhesive systems. CLINICAL SIGNIFICANCE: The increasing use of Er:YAG laser is important to evaluate the influence of this irradiation on the adhesion of restorative materials. Thus, to obtain the longevity of the restorative procedures, it is necessary to know the result of the association of the present adhesive systems to the irradiated substrate.

Protective Effect of Adhesive Systems associated with Neodymium-doped Yttrium Aluminum Garnet Laser on Enamel Erosive/Abrasive Wear.

AIM: This study evaluated the efficacy of self-etching adhesive systems associated or not associated with the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser on the protection against enamel erosive/abrasive wear. MATERIALS AND METHODS: Bovine enamel specimens were demineralized with 0.3% citric acid (5 minutes). The samples were randomly assigned to eight groups (n = 20): SB - Single Bond Universal (3M/ESPE); SB+L - Single Bond Universal + laser (80 mJ/10 Hz); FB - Futurabond U (Voco); FB+L -Futurabond U + laser; GEN - G-aenial bond (GC); GEN+L -G-aenial bond + laser; L - laser irradiation; and C - no treatment. The laser was applied before light curing. The samples were subjected to erosive/abrasive challenges (0.3% citric acid - 2 minutes and tooth brushing four times daily for 5 days). Enamel surface loss was recovered profilometrically by comparison of baseline and final profiles. The adhesive layer thickness, retention percentage of the protective layer, and microhardness of cured adhesive were measured. Data were analyzed using one-way analysis of variance and Tukey's test (5%). RESULTS: There were significant differences for all parameters (p = 0.0001). Mean values ± SD and results of the Tukey's test were: Surface wear: GEN - 4.88 (±1.09)a, L - 5.04 ± 0.99)a, FB - 5.32 (±0.93)ab, GEN + L - 5.46 (±1.27)abc, SB + L - 5.78 (±1.12)abc, FB + L - 6.23 (±1.25)bc, SB - 6.35 (±1.11)c, and C - 6.46 (±0.61)c; layer thickness: GEN - 15.2 (±8.63)c, FB - 5.06 (±1.96)a, GEN + L - 13.96 (±7.07)bc, SB + L - 4.24 (±2.68)a, FB + L - 9.03 (±13.02)abc, and SB - 7.49 (±2.80)ab; retention: GEN - 68.89 (±20.62)c, FB - 54.53 (±24.80)abc, GEN + L - 59.90 (±19.79)abc, SB + L - 63.37 (±19.30)bc, FB + L - 42.23 (±17.68) a, and SB - 47.78 (±18.29)ab; microhardness: GEN - 9.27 (±1.75)c; FB - 6.99 (±0.89)b; GEN + L - 6.22 (±0.87)ab; SB + L - 15.48 (±2.51)d; FB + L - 10.67 (±1.58)c; SB - 5.00 (±1.60)a. CONCLUSION: The application of Futurabond U and G-aenial bond on enamel surface, as well as the Nd:YAG laser irradiation alone, was able to reduce the enamel wear. The use of laser after the adhesive systems did not improve their efficacy. CLINICAL SIGNIFICANCE: Erosive/abrasive wear is a prevalent condition in clinical practice affecting many patients. The association of adhesive systems and Nd:YAG laser is of considerable clinical interest because it assesses new treatments to reduce the erosive/abrasive wear that would help dentists in clinical treatment decisions to reduce enamel wear and achieve a successful treatment.

Influence of Dentin Deproteinization on Bonding Degradation: 1-year Results.

INTRODUCTION: The decalcification protocol of dentin surface with sodium hypochlorite removes the exposed collagen fibrils and could improve the longevity of the bonding interface. This study evaluated the influence of collagen removal with 10% sodium hypochlorite (10% NaOCl) on the longitudinal shear bond strength (SBS) of adhesives to dentin. MATERIALS AND METHODS: Seventy-two extracted human molars were sectioned and the buccal and lingual surfaces were flattened and acid etched with 37% phosphoric acid for 15 seconds. The specimens were divided into six groups (n = 12 teeth - 24 sections), according to adhesive and collagen removal protocol: group 1: UNO Dentastic; group 2: Prime and Bond NT; group 3: Single Bond; group 4: 10% NaOCl + UNO Dentastic; group 5: 10% NaOCl + Prime and Bond NT; group 6: 10% NaOCl + Single Bond. Composite Z100 buildup was prepared, and the SBS test was assessed after 24 hours and 1 year. Data were submitted to three-way analysis of variance (ANOVA) and Tukey tests (p < 0.05). RESULTS: The mean values (MPa) were for 24 hours: G1: 22.45B; G2: 7.90DE; G3: 12.56CD; G4: 19.85BC; G5: 33.73A; G6: 20.77B; and for 1 year: G1: 2.43E; G2: 2.26E; G3: 4.3DE; G4: 18.79BC; G5: 26.49AB; G6: 22.73B. CONCLUSION: Dentin deproteinization treatment with 10% NaOCI influenced the SBS compared with conventional treatment. The negative influence on SBS detected for conventional groups at 1-year interval was not detected for deproteinized groups. CLINICAL RELEVANCE: The longevity of hybrid layer is critical due to the hydrolysis process at the adhesive interface over time. The use of 10% NaOCl deproteinization protocol might improve the longevity of bonding in adhesive restorations.

Influence of Different Etching Modes on Bond Strength to Enamel using Universal Adhesive Systems.

INTRODUCTION: The adhesive systems and the techniques currently used are designed to provide a more effective adhesion with reduction of the protocol application. The objective of this study was to evaluate the bond strength of universal adhesive systems on enamel in different etching modes (self-etch and total etch). MATERIALS AND METHODS: The mesial and distal halves of 52 bovine incisors, healthy, freshly extracted, were used and divided into seven experimental groups (n = 13). The enamel was treated in accordance with the following experimental conditions: FUE-Universal System - Futurabond U (VOCO) with etching; FUWE - Futurabond U (VOCO) without etching; SB-Total Etch System - Single Bond 2 (3M); SBUE-Universal System - Single Bond Universal (3M ESPE) with etching; SBUWE - Single Bond Universal (3M ESPE) without etching; CLE-Self-etch System - Clearfil SE Bond (Kuraray) was applied with etching; CLWE - Clearfil SE Bond (Kuraray) without etching. The specimens were made using the composite spectrum TPH (Dentsply) and stored in distilled water (37 ± 1°C) for 1 month. The microshear test was performed using the universal testing machine EMIC DL 2000 with the crosshead speed of 0.5 mm/minute. The bond strength values were analyzed using statistical tests (Kruskal-Wallis test and Mann-Whitney test) with Bonferroni correction. RESULTS: There was no statistically significant difference between groups (p < 0.05), where FUE (36.83 ± 4.9 MPa) showed the highest bond strength values and SBUWE (18.40 ± 2.2 MPa) showed the lowest bond strength values. The analysis of adhesive interface revealed that most failures occurred between the interface composite resin and adhesive. CONCLUSION: The universal adhesive system used in dental enamel varies according to the trademark, and the previous enamel etching for universal systems and the self-etch both induced greater bond strength values. CLINICAL SIGNIFICANCE: Selective enamel etching prior to the application of a universal adhesive system is a relevant strategy for better performance bonding.