Modeler liquids: Effect on the cohesive strength, color and staining resistance of stratified resin composite restorations.

PURPOSE: To evaluate the effect of filled and unfilled modeler liquids on the cohesive strength and color stability when applied in between the resin composite layers in the stratification technique and on the uppermost surface layer. METHODS: For the cohesive strength test (n= 10), 30 cylindrical samples were packed into a Teflon mold (6x2 mm) in 2 mm increments. Firstly, a dentin-shade resin composite (Empress Direct) was placed, followed by the accommodation of a body-shade resin composite (Filtek Z350 XT) and an enamel-shade resin composite (Estelite Omega). Before photoactivation of each increment, an unfilled (Signum Liquid) or filled (Modeling Resin) modeler liquid was applied between the first and second layers and on the uppermost surface layer. The control group (n= 10) did not receive modeler liquid. Cohesive strength was measured in a universal testing machine. For the color test (n= 10), the other 30 samples were fabricated for the cohesive strength test, except for the difference in the diameter (6x6 mm). Before and after the staining of the samples, color was measured using the CIEL*a*b* system with a spectrophotometer (EasyShade). Data were submitted to ANOVA, Kruskal-Wallis test, or Mann-Whitney test (α= 5%). RESULTS: Modeler liquids significantly increased cohesive strength (P= 0.008), while ΔEab (P= 0.003) and ΔE00 (P= 0.005) values presented significantly lower changes for the groups that received modeler liquids, with no significant difference between unfilled and filled modeler liquids. CLINICAL SIGNIFICANCE: Apart from increasing the interfacial strength of stratified restorations, modeler liquids minimized staining.

Salivary, acidic and enzymatic degradation of resin composite subjected to different finishing and polishing systems.

PURPOSE: To evaluate the effect of different finishing and polishing systems on the surface roughness of a resin composite subjected to simulated saliva-, acid-, and enzyme-induced degradation. METHODS: 160 specimens (n= 40) were fabricated with Filtek Z350 XT nanofilled composite and analyzed for average surface roughness (Ra). The specimens were finished and polished using: AD - Al2O3-impreginated rubberized discs (medium, fine, and superfine grit, Sof-Lex); SD - silicon carbide and Al2O3-impregnated rubberized discs (coarse, medium and fine grit, Jiffy,); MB - 12- and 30-multiblade burs. The control group (CT) (n= 40) comprised specimens with a Mylar-strip-created surface. Specimens from each group were immersed in 1 mL of one of the degradation methods (n= 10): artificial saliva (ArS: pH 6.75), cariogenic challenge (CaC: pH 4.3), erosive challenge (ErC: 0.05M citric acid, pH 2.3) or enzymatic challenge (EzC: artificial saliva with 700 µg/mL of albumin, pH 6.75). The immersion period simulated a time frame of 180 days. Ra measurements were also performed at the post-polishing and post-degradation time points. The data were evaluated by three-way ANOVA for repeated measures and the Tukey tests. RESULTS: There was significant interaction between the finishing/polishing system and the degradation method (P= 0.001). AD presented the greatest smoothness, followed by SD. After degradation, CT, AD and SD groups became significantly rougher, but not the MB group, which presented no difference in roughness before or after degradation. CT and AD groups showed greater roughness in CaC, ErC and EzC than in ArS. The SD group showed no difference in roughness when the specimens were polished with CaC, EzC or ArS, but those treated with ErC had greater roughness. In the MB group, the lower roughness values were found after using CaC and EzC, while the higher values were found using ErC or ArS. CLINICAL SIGNIFICANCE: As far as degradation resistance of nanofilled composite to hydrolysis, bacterial and dietary acids and enzymatic reactions is concerned, restorations that had been finished and polished with Al2O3-impregnated discs had the smoothest surfaces.

Objective assessment of simulated non-carious cervical lesion by tridimensional digital scanning - An in vitro study.

OBJECTIVE: Clinical assessment of progression of non-carious cervical lesions (NCCLs) is currently based on subjective methods. We hypothesize that 3D digital intraoral scanners (IOS) can provide quantitative outcomes for objective measuring and monitoring of NCCLs. This in vitro study verified the reliability of IOS to monitor dental structure loss of simulated NCCLs, in comparison to a reference bench-top 3D optical profilometer (BTS). METHODS: NCCLs of different severity levels (early, moderate, or severe, n = 150) were simulated in a preceding study. Impressions of the lesions were taken and scanned with both BTS (ProScan; Scantron) and IOS (TRIOS4; 3Shape). Generated 3D images were analyzed for volumetric tooth loss (mm3) by superimposition followed by subtraction analysis. ProForm (Scantron) and WearCompare (Leeds Digital Dentistry) software were used in association to BTS and IOS, respectively. Agreement was assessed using intraclass correlation coefficient (ICC, alpha=0.05) and Bland-Altman plots. RESULTS: ICC (confidence interval at 95 %) between IOS and BTS for all data combined was 0.962 (0.942-0.973), showing excellent reliability. Subset analyses showed that NCCLs with lower volume loss (early- and moderate-stage lesions) resulted in moderate ICCs, whereas severe lesions showed excellent ICC. Bland-Altman plots demonstrated general good agreement, with narrower limits for early stage-lesions. CONCLUSION: IOS data demonstrated good agreement to BTS, when measuring tooth structure loss in simulated NCCLs, with particularly higher ICC in more severe lesions. Considering the accessibility and ease-of-use, IOS showed to be a good alternative for the objective assessment of NCCLs in vitro. CLINICAL SIGNIFICANCE: 3D intraoral scanners' accessibility and objectivity make them potentially valuable tools for assessing and monitoring NCCLs.

Stability of dentin matrix treated with caffeic acid phenethyl ester at different concentrations

Aim: The aim of this study was to investigate the impact of pretreatment with ethanolic solutions of caffeic acid phenethyl ester (CAPE) at varying concentrations on the dentin collagen matrix, specifically focusing on its biomodification potential. This was assessed through evaluations of the modulus of elasticity and changes in mass. Methods: Seventy dentin collagen matrices (demineralized sticks) were prepared to receive treatments with ethanolic solutions of CAPE at concentrations of 0.05%, 0.1%, 0.5%, or 2.5%, or with control treatment solutions (distilled water or ethanol) for one hour. The dentin matrices were evaluated for modulus of elasticity and mass before (baseline), immediately after treatment (immediately), and after storage in Simulated Body Fluid (SBF) for time intervals of 1 and 3 months. Results: Generalized linear models for repeated measures over time indicated no significant differences between groups (p=0.7530) or between different time points (p=0.4780) in terms of the modulus of elasticity. Regarding mass variation, no differences were observed in the time interval between 1 month and the immediate time (p=0.0935). However, at the 3-month mark compared to the immediate time, the 0.1% CAPE group exhibited less mass loss compared to the water group (p=0.0134). Conclusion: This study concludes that various concentrations of CAPE in an ethanolic solution did not affect the modulus of elasticity of dentin, suggesting that CAPE lacks biomodifying potential in this context. However, it was observed that 0.1% CAPE positively influenced the variation in mass over different evaluation time intervals

Does the combination of whitening toothpaste and hydrogen peroxide bleaching increase the surface roughness and change the morphology of a nanofilled composite?

Aim: To evaluate changes in the surface roughness and morphology of a nanofilled composite following toothbrushing with a whitening (WT) or regular toothpaste (RT), alone or combined with 35% hydrogen peroxide bleaching (HP). Methods: Seventy disc-shaped nanofilled composite (Filtek Z350XT) specimens were randomly divided into groups (n=10): WT, RT, TB (without toothpaste ­ control) or the combinations WT/ HP, RT/HP, TB/HP and HP. All groups underwent toothbrushing simulation (60,000 cycles) and bleaching treatment (4 sessions). Mean surface roughness (Ra, µm) was measured before (T0) and after treatments (TB). Surface morphology was assessed by scanning electron microscopy (SEM) at TB. Mean Ra was analyzed using general mixed models and multiple comparisons by the Tukey-Kramer test (α=5%). Results: HP caused no surface roughness changes on the nanofilled composite after treatment (p>0.05). RT toothbrushing, combined or not with HP, increased the surface roughness (p<0.05). WT and WT/ HP protocols had no effect on the surface roughness of the composite (p>0.05). The nanofilled composite submitted to RT toothbrushing combined with HP (RT/HP) presented substantial surface alterations under SEM, showing deep depressions and round-shaped defects. Toothbrushing with RT combined with the bleaching agent increased exposure of the inorganic fillers. Conclusion: WT toothbrushing, regardless of HP combination, or the single HP protocol had no effect on the surface roughness of the nanofilled composite. However, RT combined with HP negatively affected surface roughness and presented the most noticeable surface changes among groups

Effect of simplified or multi-step polishing techniques on roughness and color stability of resin composites.

PURPOSE: To evaluate the impact of simplified or multi-step polishing techniques on the roughness, color, and susceptibility to staining of different resin composites. METHODS: Discs (Ø6 mm x 2 mm) were obtained from different resin composites [nanofilled (Z350XT), suprananofilled (Estelite Omega), and nanohybrid (Forma)]. The specimens (n= 15) were submitted to a simplified protocol using abrasive discs (Sof-Lex) and spiral discs (Diacomp Plus Twist), or a multi-step protocol using abrasive discs (Sof-Lex), abrasive points (Jiffy), silicon carbide brush and felt disc with diamond pastes (Diamond Polish). The specimens were evaluated initially for roughness (Ra) and color (CIEL*a*b*, CIEDE 2000), after completing the polishing protocol, and after exposure to a coffee solution (pH= 5.01). The data were analyzed according to the variables, using generalized linear models, and the Friedman, Nemenyi, Kruskal-Wallis, Dunn, and Mann-Whitney tests (α= 0.05). RESULTS: The nanohybrid resin composite showed an increase in Ra following use of both polishing methods (P= 0.038). Both techniques promoted an increase in L* values after polishing; however, the general color changes (ΔEab and ΔE00) were greater after the multi-step polishing (P< 0.05). After immersion in coffee, the multi-step polished groups of the nanohybrid and suprananofilled resin composite showed higher L* values than the simplified polishing groups (P= 0.023), and the nanofilled resin composite showed higher ΔEab and ΔE00 values than the other resin composites, regardless of the polishing technique (P< 0.05). CLINICAL SIGNIFICANCE: The choice of the resin composite had a greater effect on roughness, color stability and susceptibility to staining than the polishing technique. However, luminosity after coffee staining was higher with the multi-step polishing technique.

Effectiveness of changing the color of darker teeth is potentiated by association with violet LED light.

BACKGROUND: The effectiveness of in-office bleaching protocols performed with violet LED light either combined with a bleaching agent containing 37% carbamide peroxide, or not, was determined by comparing teeth with different degrees of darkening. METHODOLOGY: Eighty bovine incisors were separated into groups of "light" teeth (luminosity greater than or equal to B3) and "dark" teeth (less than or equal to A3.5) to receive the protocols: HP - 35% hydrogen peroxide (Whiteness HP), CP - 37% carbamide peroxide (Whiteness SuperEndo), LED - violet LED light (Bright Max Whitening), CPLED - CP associated with the LED. For color analysis the CIEL*a*b* e WID, ΔEab, ΔE00 e ΔWID parameters were used. Data were analyzed using Mann-Whitney, Kruskal-Wallis, Dunn, Friedman or Nemenyi tests (α = 5%). RESULTS: HP and CP resulted in similar color change values (ΔEab, ΔE00 e ΔWID) for light and dark teeth (p > 0.05). Dark teeth showed better bleaching effectiveness (ΔEab, ΔE00 e ΔWID) than light teeth when CPLED was used (p < 0.05). LED showed color change that were below the limits of acceptability and perceptibility for ΔWID. CONCLUSION: light teeth are effectively bleached with the use of HP or CP, whereas dark teeth respond better to treatment with the CPLED protocol. Violet LED used alone did not show a satisfactory result.

Precision of polyether ether ketone (PEEK) or cobalt-chrome implant bar fit to implants after mechanical cycling.

Based on its mechanical properties, PEEK (polyether-ether-ketone) might be useful in restorative procedures. In oral rehabilitation, its viability has been studied mainly for prostheses and dental implants. AIM: The aim of this study was to evaluate the fit accuracy of dental implant bars made of either PEEK or cobalt-chrome submitted to cycling mechanics. MATERIALS AND METHOD: This was an experimental in vitro study, where units were treated with two implants and mini-abutments, joined by cobalt-chrome or polyether-ether-ketone PEEK bars. A total 20 bars were prepared (n=10 per group) and subjected to mechanical cycling tests (1 million cycles on the distal cantilever of the bar in the vertical direction, 120N and sinusoidal loading, at a frequency of 2Hz). The fit at the abutment/implant interface was measured before and after cycling, and the counter-torque of the vertical screw of the mini abutments was measured after cycling, using a digital torquemeter. Data were analyzed by three-way ANOVA and Tukey's test at 5% significance level. RESULTS: No statistically significant interaction was found among the three factors considered (bar material, implant positioning and mechanical cycling) (p = 0.592). No significant difference was identified in the interaction between bar material and implant positioning (p = 0.321), or between implant positioning and mechanical cycling (p = 0.503). The association between bar material and mechanical cycling was statistically significant (p = 0.007), with the cobalt-chrome bar resulting in greater misfit with mechanical cycling. There was no difference in counter-torque values between groups. CONCLUSIONS: The PEEK bar provided better fit of the mini abutments to the implants, even after mechanical cycling. The counter-torque of the screws was similar in all scenarios considered.

O PEEK (Poli-éter-éter-cetona) é um material considerado para uso em procedimentos restauradores devido às suas propriedades mecânicas. Na reabilitação oral, sua viabilidade tem sido estudada principalmente para uso em próteses e implantes dentários. Objetivos: O objetivo deste estudo foi avaliar a precisão da adaptação de duas barras diferentes do tipo protocolo confeccionadas em PEEK ou Cobalto-Cromo, após serem submetidas à mecânica ciclística. Materiais e Método: As unidades experimentais foram constituídas por barras confeccionadas em Poli-ether-ether-Ketone (PEEK) e em Cobalto-Cromo (Co-Cr). Trata-se de um estudo experimental, in vitro, onde verificou-se unidades constituídas por dois implantes e mini pilares unidos com barras de Cobalto-Cromo ou PEEK. Foram confeccionados um total de 20 barras (n=10 em cada grupo) e as barras foram submetidas a ensaios de ciclagem mecânica (1 milhão de ciclos no cantilever distal da barra no sentido vertical, 120N e carregamento senoidal, a uma frequência de 2Hz). Antes e após a ciclagem realizou-se a mensuração da desadaptação na interface pilar/implante e após a ciclagem foi medido o contra-torque do parafuso vertical dos mini-pilares através de torquímetro digital TQ 8800 (LT Lutron, Taiwan). Os dados foram submetidos a ANOVA a três critérios e teste de Tukey ao nível de significância a 5%. Resultados: Constatou-se que não houve interação estatisticamente significativa entre os três fatores estudados, ou seja, entre o material da barra, o posicionamento do implante e a ciclagem mecânica (p = 0,592). Também não se identificou diferença estatística significativa da interação entre o material da barra e o posicionamento do implante (p = 0,321), nem entre o posicionamento do implante e a ciclagem mecânica (p = 0,503). Já a associação entre o material da barra e a ciclagem mecânica foi estatisticamente significativa (p = 0,007), onde a barra de Cobalto-Cromo resultou em maior desadaptação com a ciclagem mecânica. Não houve diferença nos valores dos contra-torques entre os grupos. Conclusões: Conclui-se que a barra de protocolo fabricada em PEEK proporcionou melhor adaptação dos mini pilares aos implantes mesmo após a ciclagem mecânica. Por fim, o contra-torque dos parafusos foi semelhante em todos os cenários avaliados.

Effect of chemical or mechanical finishing/polishing and immersion in staining solutions on the roughness, microhardness, and color stability of CAD-CAM monolithic ceramics.

During the manufacture of ceramic restorations there is an important step of finishing and polishing and the effects of different types of these procedures on the surface characteristics of ceramics are not known for sure. AIM: To evaluate the effects of various surface treatments and immersion in coloring substances on the roughness, microhardness, and color stability of CAD-CAM monolithic ceramics. MATERIALS AND METHOD: The ceramics used were lithium disilicate reinforced with zirconium dioxide (Suprinity), lithium disilicate (E.max) or leucite (Empress). They were subjected to two surface treatments: glazing (group G) (n=20) or mechanical polishing (group P) (n=20). Then they were divided into two subgroups (n=10) to be treated with the staining substance (coffee or water). Roughness, microhardness and color were measured before and after treatment. Data were subjected to analysis of variance and multiple comparisons were performed with Tukey tests at 5% significance level. RESULTS: Roughness was lower in all tested ceramics after polishing than after glazing. Microhardness was the same for polished and glazed E.max, higher in glazed than polished Empress, and higher in polished than glazed Suprinity. Analysis of the effects of glazing and polishing on the individual ceramics showed that the ΔE2000 and ΔWID data of the E.max ceramic subjected to polishing showed greater change. Mechanical polishing is a good option for surface treatment of monolithic ceramics. CONCLUSION: Glazing was inferior and less satisfactory than polishing. Glazing generates changes that can lead to color instability.

Durante a confecção de restaurações cerâmicas existe uma importante etapa dos procedimentos de acabamento e polimento. Os efeitos de diferentes tipos desses procedimentos nas características superficiais das cerâmicas não são conhecidos com certeza. Objetivo: Avaliar os efeitos de vários tratamentos de superfície e imersão em substâncias corantes na rugosidade, microdureza e estabilidade de cor de cerâmicas monolíticas CAD-CAM. Materiais e Métodos: As cerâmicas utilizadas foram dissilicato de lítio reforçado com dióxido de zircônio (Suprinity), dissilicato de lítio (E.max) ou leucita (Empress). Foram submetidos a dois tratamentos de superfície: glazeamento (grupo G) (n=20) ou polimento mecânico (grupo P) (n=20). Em seguida, foram divididos em dois subgrupos (n=10) para serem tratados com a substância corante (café ou água). Rugosidade, microdureza e cor foram medidas antes e após o tratamento. Os dados foram submetidos à análise de variância e as comparações múltiplas foram realizadas com testes de Tukey ao nível de 5% de significância. Resultados: A rugosidade foi menor em todas as cerâmicas testadas após o polimento do que após o glazeamento. A microdureza foi a mesma para o E.max polido e vidrado, maior no Empress vidrado do que no polido, e maior no Suprinity polido do que no vidrado. A análise dos efeitos do esmaltação e polimento nas cerâmicas individuais mostrou que os dados ΔE2000 e ΔWID da cerâmica E.max submetida ao polimento apresentaram maior alteração. O polimento mecânico é uma boa opção para o tratamento superficial de cerâmicas monolíticas. Conclusão: A aplicação do glazing foi inferior e menos satisfatório que o polimento, gerando alterações que podem levar à instabilidade da cor.

Hybrid light applied with 37% carbamide peroxide bleaching agent with or without titanium dioxide potentializes color change effectiveness.

BACKGROUND: The effectiveness of dental color change was assessed by incorporating titanium dioxide (TiO2) into 37% carbamide peroxide bleaching agent associated with hybrid light. METHODOLOGY: Fifty bovine incisors were selected to receive the bleaching treatment, and separated into five groups (n = 10): 35% hydrogen peroxide (HP) (Whiteness HP, FGM/HP); 37% carbamide peroxide (CP) (Whiteness SuperEndo, FGM/CP); CP + hybrid light (HL) (CP HL); CP + 1% TiO2 (CP TiO2); CP TiO2 + hybrid light (CP TiO2 HL). The bleaching gels were applied to the dental surface for 30 min. Hybrid light (Whitening Plus, DMC/infrared laser diodes + blue LEDs +violet LEDs) was applied with 1 min of active light, alternating with 1 min of pause. A spectrophotometer (VITA Easyshade® Advance, Vita) was used to determine the color of the dental elements at baseline and time points after the 1st, 2nd and 3rd bleaching sessions. Color change effectiveness was evaluated using Vita Classical, CIEL*a*b*, WID and ΔEab, ΔE00 and ΔWID parameters. RESULTS: Generalized mixed linear models for repeated measures (α = 5%) showed significant decrease in Vita Classical scores and a* and b* values, as well as an increase in L* and ∆WID values for all the groups. Higher color change values for ΔEab were observed for CP HL and CP TiO2 HL, while those of ΔE00 and ΔWID were higher for CP TiO2 HL at the end of the bleaching treatment. CONCLUSION: Hybrid light applied with TiO2 incorporated into CP potentiated the effectiveness of the color change in the tooth structure.

Smoothness provided by a one-step finishing and polishing system and its maintenance after 12-month aging.

PURPOSE: To evaluate the smoothness provided by a one-step finishing and polishing system and its maintenance after hydrothermal aging and brushing of a nanofilled resin composite. METHODS: 96 samples of the nanofilled composite Filtek Z350 XT were fabricated, which, after initial average roughness (Ra) analysis, were randomly distributed into three groups, according to the selected finishing and polishing system. The multi-step systems Sof-Lex (aluminum oxide discs) and Jiffy (bullet-shaped abrasive rubbers), and the one-step system OneGloss (bullet-shaped abrasive rubber) were used. After finishing and polishing, a new Ra measurement was performed, and then half of the samples from each group were stored in artificial saliva for 12 months, while the other half underwent aging processes associating hydrothermal cycles (10,000 cycles at 5-55°C) followed by brushing (5,500 strokes), with a mid-abrasive (Crest Cavity Protection) dentifrice slurry, simulating a 12-month period in the oral cavity. Final Ra measurements were performed, and data were analyzed by generalized linear model and Tukey's test (α= 5%). RESULTS: There was interaction between finishing and polishing system and aging (P< 0.001). The one-step abrasive rubber point provided significantly higher Ra values compared to the multi-step systems, and with the discs there was higher smoothness than with the rubber point sequence. This result was maintained after 12 months in artificial saliva, but after hydrothermal cycles followed by brushing, one-step and multi-step abrasive rubber points no longer significantly differed from each other. Only for the one-step system, hydrothermal cycles followed by brushing significantly reduced Ra. CLINICAL SIGNIFICANCE: Although hydrothermal cycles followed by brushing may have increased the smoothness of nanofilled composite finished and polished with the one-step system, only the multi-step system provided a surface within the roughness threshold to avoid biofilm retention.

Varnish with S-PRG filler reduces dentin permeability after erosive/abrasive challenge.

PURPOSE: To evaluate the effect of different varnishes on dentin permeability to erosive/abrasive challenges. METHODS: 60 superficial dentin discs were randomly allocated to six groups (n=10): Duraphat, PRG Barrier Coat, Clinpro XT, Profluorid, Fluor Protector S and untreated (control). Permeability tests were carried out: after acid conditioning, after treatment, and after abrasive/erosive challenges. The abrasive-erosive challenges were performed for 5 days (citric acid and in remineralizing saliva), as well as abrasion with toothpaste slurry (Colgate Total 12). Scanning electron microscopy (SEM) images were obtained of the dentin surfaces (5,000x) after the treatments, and after the erosive/abrasive challenges. RESULTS: Kruskal-Wallis and Dunn tests showed that all the varnishes promoted a decrease in dentin permeability directly after application, with Clinpro XT showing the highest percentage (69.52%) of dentin sealing (P= 0.0188). After the erosive/abrasive challenge, only PRG Barrier Coat varnish showed dentin sealing ability with reduced dentin permeability (42.16%) (P= 0.0014). However, none of the applied varnishes promoted a statistically significant difference in the percentage of dentin sealing, compared with the control group (P> 0.05). Clinpro XT showed a higher percentage of dentin sealing, while only PRG Barrier Coat showed reduced dentin permeability after the erosive/abrasive challenge. CLINICAL SIGNIFICANCE: Varnish containing S-PRG filler has the efficacy needed to be used as a coating material to reduce dentin permeability in situations of erosive/abrasive challenges.

Long-term bond strength of ormocer-based resin composites using a universal adhesive used in different adhesive strategies.

PURPOSE: To evaluate over time the bond strength to dentin of different resin composites (RBCs) associated with the universal adhesive system applied with self-etching or total-etching strategies. METHODS: 60 human third molars were obtained, randomly divided into experimental groups (n= 10) according to RBCs: methacrylate-based nanofilled (Z350 XT); low-viscosity Ormocer-based bulk-fill (Admira Fusion X-base Universal); or high-viscosity Ormocer-based bulk-fill composite (Admira Fusion X-tra). The adhesion procedure was performed using a universal adhesive (Futurabond U) applied in self-etching or total-etching mode. Occlusal preparations (Class I) were made, measuring 4 mm in mesiodistal length, 4 mm in depth, and 3 mm in buccolingual height. The cavities were restored considering the RBCs and adhesive strategies, and the light curing was performed using a LED unit (BluePhase) as recommended by the manufacturers. For this, the nanofilled RBCs were inserted by the oblique incremental technique while the bulk-fill RBCs were inserted in single increments. The samples were stored in water for 24 hours in an oven; to be sectioned, the sticks were randomly separated, stored in distilled water for 24 hours (immediate) or 12 months (long-term), and taken to the universal machine for a microtensile test (MPa). The fractured sticks were examined to classify the type of fracture. The results were analyzed by ANOVA and Tukey's test (α= 0.05). RESULTS: The MPa values of methacrylate-based nanofilled or high-viscosity Ormocer-based RBC were not affected by the strategy used to apply the universal adhesive system (P> 0.05). However, for the low-viscosity Ormocer-based RBC, higher values were obtained when the total-etching strategy was used compared to the self-etching mode (P< 0.05). After 12 months, when using the total-etching strategy low-viscosity Ormocer-based RBC, higher MPa values were obtained compared to the other materials (P< 0.05). CLINICAL SIGNIFICANCE: Regardless of the adhesive strategy used, the high-viscosity RBCs, whether based on methacrylate or Ormocer, showed similar adhesive behavior. Low-viscosity Ormocer-based RBC showed greater long-term bond strength associated with the universal adhesive applied in the total-etching strategy.

Precision of polyether ether ketone (PEEK) or cobalt-chrome implant bar fit to implants after mechanical cycling / Precisão da adaptação de barras tipo protocolo confeccionados em polyetheretherketone (PEEK) ou cobalto cromo sobre implante após ciclagem mecânica

ABSTRACT Based on its mechanical properties, PEEK (polyether-ether-ketone) might be useful in restorative procedures. In oral rehabilitation, its viability has been studied mainly for prostheses and dental implants. Aim: The aim of this study was to evaluate the fit accuracy of dental implant bars made of either PEEK or cobalt-chrome submitted to cycling mechanics. Materials and Method: This was an experimental in vitro study, where units were treated with two implants and mini-abutments, joined by cobalt-chrome or polyether-ether-ketone PEEK bars. A total 20 bars were prepared (n=10 per group) and subjected to mechanical cycling tests (1 million cycles on the distal cantilever of the bar in the vertical direction, 120N and sinusoidal loading, at a frequency of 2Hz). The fit at the abutment/implant interface was measured before and after cycling, and the counter-torque of the vertical screw of the mini abutments was measured after cycling, using a digital torquemeter. Data were analyzed by three-way ANOVA and Tukey's test at 5% significance level. Results: No statistically significant interaction was found among the three factors considered (bar material, implant positioning and mechanical cycling) (p = 0.592). No significant difference was identified in the interaction between bar material and implant positioning (p = 0.321), or between implant positioning and mechanical cycling (p = 0.503). The association between bar material and mechanical cycling was statistically significant (p = 0.007), with the cobalt-chrome bar resulting in greater misfit with mechanical cycling. There was no difference in counter-torque values between groups. Conclusions: The PEEK bar provided better fit of the mini abutments to the implants, even after mechanical cycling. The counter-torque of the screws was similar in all scenarios considered.

RESUMO O PEEK (Poli-éter-éter-cetona) é um material considerado para uso em procedimentos restauradores devido às suas propriedades mecânicas. Na reabilitação oral, sua viabilidade tem sido estudada principalmente para uso em próteses e implantes dentários. Objetivos: O objetivo deste estudo foi avaliar a precisão da adaptação de duas barras diferentes do tipo protocolo confeccionadas em PEEK ou Cobalto-Cromo, após serem submetidas à mecânica ciclística. Materiais e Método: As unidades experimentais foram constituídas por barras confeccionadas em Poli-ether-ether-Ketone (PEEK) e em Cobalto-Cromo (Co-Cr). Trata-se de um estudo experimental, in vitro, onde verificou-se unidades constituídas por dois implantes e mini pilares unidos com barras de Cobalto-Cromo ou PEEK. Foram confeccionados um total de 20 barras (n=10 em cada grupo) e as barras foram submetidas a ensaios de ciclagem mecânica (1 milhão de ciclos no cantilever distal da barra no sentido vertical, 120N e carregamento senoidal, a uma frequência de 2Hz). Antes e após a ciclagem realizou-se a mensuração da desadaptação na interface pilar/implante e após a ciclagem foi medido o contra-torque do parafuso vertical dos mini-pilares através de torquímetro digital TQ 8800 (LT Lutron, Taiwan). Os dados foram submetidos a ANOVA a três critérios e teste de Tukey ao nível de significância a 5%. Resultados: Constatou-se que não houve interação estatisticamente significativa entre os três fatores estudados, ou seja, entre o material da barra, o posicionamento do implante e a ciclagem mecânica (p = 0,592). Também não se identificou diferença estatística significativa da interação entre o material da barra e o posicionamento do implante (p = 0,321), nem entre o posicionamento do implante e a ciclagem mecânica (p = 0,503). Já a associação entre o material da barra e a ciclagem mecânica foi estatisticamente significativa (p = 0,007), onde a barra de Cobalto-Cromo resultou em maior desadaptação com a ciclagem mecânica. Não houve diferença nos valores dos contra-torques entre os grupos. Conclusões: Conclui-se que a barra de protocolo fabricada em PEEK proporcionou melhor adaptação dos mini pilares aos implantes mesmo após a ciclagem mecânica. Por fim, o contra-torque dos parafusos foi semelhante em todos os cenários avaliados.

Effect of chemical or mechanical finishing/polishing and immersion in staining solutions on the roughness, microhardness, and color stability of CAD-CAM monolithic ceramics / Efeito do acabamento/polimento químico ou mecânico e imersão em soluções manchantes na rugosidade, microdureza e estabilidade da cor em cerâmicas monolíticas CAD-CAM

ABSTRACT During the manufacture of ceramic restorations there is an important step of finishing and polishing and the effects of different types of these procedures on the surface characteristics of ceramics are not known for sure. Aim: To evaluate the effects of various surface treatments and immersion in coloring substances on the roughness, microhardness, and color stability of CAD-CAM monolithic ceramics. Materials and Method: The ceramics used were lithium disilicate reinforced with zirconium dioxide (Suprinity), lithium disilicate (E.max) or leucite (Empress). They were subjected to two surface treatments: glazing (group G) (n=20) or mechanical polishing (group P) (n=20). Then they were divided into two subgroups (n=10) to be treated with the staining substance (coffee or water). Roughness, microhardness and color were measured before and after treatment. Data were subjected to analysis of variance and multiple comparisons were performed with Tukey tests at 5% significance level. Results: Roughness was lower in all tested ceramics after polishing than after glazing. Microhardness was the same for polished and glazed E.max, higher in glazed than polished Empress, and higher in polished than glazed Suprinity. Analysis of the effects of glazing and polishing on the individual ceramics showed that the ΔE2000 and ΔWID data of the E.max ceramic subjected to polishing showed greater change. Mechanical polishing is a good option for surface treatment of monolithic ceramics. Conclusion: Glazing was inferior and less satisfactory than polishing. Glazing generates changes that can lead to color instability.

RESUMO Durante a confecção de restaurações cerâmicas existe uma importante etapa dos procedimentos de acabamento e polimento. Os efeitos de diferentes tipos desses procedimentos nas características superficiais das cerâmicas não são conhecidos com certeza. Objetivo: Avaliar os efeitos de vários tratamentos de superfície e imersão em substâncias corantes na rugosidade, microdureza e estabilidade de cor de cerâmicas monolíticas CAD-CAM. Materiais e Métodos: As cerâmicas utilizadas foram dissilicato de lítio reforçado com dióxido de zircônio (Suprinity), dissilicato de lítio (E.max) ou leucita (Empress). Foram submetidos a dois tratamentos de superfície: glazeamento (grupo G) (n=20) ou polimento mecânico (grupo P) (n=20). Em seguida, foram divididos em dois subgrupos (n=10) para serem tratados com a substância corante (café ou água). Rugosidade, microdureza e cor foram medidas antes e após o tratamento. Os dados foram submetidos à análise de variância e as comparações múltiplas foram realizadas com testes de Tukey ao nível de 5% de significância. Resultados: A rugosidade foi menor em todas as cerâmicas testadas após o polimento do que após o glazeamento. A microdureza foi a mesma para o E.max polido e vidrado, maior no Empress vidrado do que no polido, e maior no Suprinity polido do que no vidrado. A análise dos efeitos do esmaltação e polimento nas cerâmicas individuais mostrou que os dados ΔE2000 e ΔWID da cerâmica E.max submetida ao polimento apresentaram maior alteração. O polimento mecânico é uma boa opção para o tratamento superficial de cerâmicas monolíticas. Conclusão: A aplicação do glazing foi inferior e menos satisfatório que o polimento, gerando alterações que podem levar à instabilidade da cor.

Association of Non-carious Cervical Lesions with Oral Hygiene Aspects and Occlusal Force.

AIM: The purpose of this case-control (CT) study was to investigate the association between the presence of non-carious cervical lesions (NCCLs) with occlusal force and other potential risk factors. MATERIALS AND METHODS: Thirty-nine participants with NCCLs [cases (CS)] and 39 with no NCCLs [control (CT)] attending the dental clinic of the Faculdades Integradas São Pedro (FAESA), located in Brazil, were enrolled in this study. Information was collected through anamnesis, clinical examination, and a questionnaire addressing aspects related to tooth brushing, dentifrice, and mouthwash use. In clinical examination, patients were submitted to four measurements of occlusal force in the maxillary first premolars and maxillary first molars, using a strain gauge sensor of medium intensity, the Flexiforce (Tekscan, South Boston, Massachusetts, United States of America). The sensor was calibrated for the unit of measurement in Newtons (N). Data were analyzed using a student's t-test and multiple logistic regression, e with a significance level of 5%. RESULTS: There was no statistically significant difference between the case and CT groups regarding the bite force in the four measured regions. Logistic regression identified sex as a factor significantly associated with NCCLs (p = 0.020). The odds ratio showed the female sex had more chance (OR = 6.082; CI = 1.332-27.765) of having NCCLs. CONCLUSION: It is concluded that females presented a higher risk factor for NCCLs than men. In contrast, there was no association of occlusal force, as well as aspects related to brushing and deleterious habits. CLINICAL SIGNIFICANCE: Females have a higher risk factor for non-carious lesions than men.

Ozone gas therapy for tooth bleaching preserves enamel microhardness, roughness and surface micromor.

After ozone therapy for bleaching, it is important to evaluate enamel surface properties, to ensure that bleaching provides adequate conditions for sound dental substrate. Aim: The aim of this in vitro study was to evaluate the effects of a bleaching treatment with 10% carbamide peroxide (CP), with or without ozone (O), on the microhardness, roughness and micromorphology of the enamel surface. Materials and Method: Bovine enamel blocks were planed and distributed among the following three bleaching treatment groups (n=10): CP - 1 hour per day/14 days (Opalescence PF 10%/ Ultradent); O - 1 hour per day every 3 days/3 sessions (Medplus V Philozon, 60 mcg/mL and oxygen flow rate of 1 L/min); and OCP - CP with O, 1 hour per day every 3 days/3 sessions. Enamel surface microhardness (Knoop), roughness (Ra), and micromorphology by scanning electron microscopy (5,000x magnification) were determined before and after the treatments. Results: ANOVA and Tukey-Kramer's test showed that enamel microhardness remained unchanged by treatment with O and OCP (p=0.0087), but decreased by treatment with CP. Treatment with O promoted higher enamel microhardness than the other groups (p=0.0169). Generalized linear mixed models for repeated measures over time indicated treatment with CP increased enamel roughness more than OCP or O (p=0.0003). CP produced slight irregularities in enamel micromorphology after the whitening treatment. O, with or without CP, maintained the mechanical and physical properties of microhardness and enamel surface micromorphology, and either maintained or reduced surface roughness, compared to the conventional tray-delivered CP bleaching treatment. Conclusions: Treatment with 10% carbamide peroxide in trays promoted greater changes in enamel surface properties than treatments with ozone and with 10% ozonized carbamide peroxide in the office.

É importante avaliar as propriedades da superfície do esmalte após a aplicação da ozonioterapia para clareamento, para garantir que o efeito clareador proporcione condições adequadas para um substrato dentário hígido. ultório. Objetivo: O objetivo deste estudo in vitro foi avaliar os efeitos de um tratamento clareador com peróxido de carbamida (PC) a 10%, associado ou não ao ozônio (O), na microdureza, rugosidade e micromorfologia da superfície do esmalte. Materiais e Método: Blocos de esmalte bovino foram aplainados e distribuídos entre três grupos de tratamento clareador (n=10): PC - 1 hora por dia/14 dias (Opalescence PF 10%/ Ultradent); O - 1 hora por dia a cada 3 dias/3 sessões (Medplus V Philozon, 60 mcg/mL e fluxo de oxigênio de 1 L/min); e PCO - CP com O, 1 hora por dia a cada 3 dias/3 sessões. A microdureza (Knoop), a rugosidade (Ra) e a micromorfologia da superfície do esmalte avaliada por microscopia eletrônica de varredura (aumento de 5.000x) foram analisadas antes e após os tratamentos. Resultados: ANOVA e teste de Tukey-Kramer mostraram que O e PCO mantiveram os valores de microdureza do esmalte ao final do tratamento (p=0,0087), enquanto PC promoveu diminuição da microdureza. O promoveu maiores valores de microdureza do esmalte do que os outros grupos ao final do tratamento (p=0,0169). Modelos lineares generalizados mistos para medidas repetidas no tempo indicaram um aumento na rugosidade da superfície para PC, levando a maior rugosidade do esmalte ao final do tratamento, em comparação com PCO ou O (p=0,0003). PC apresentou pequenas irregularidades na micromorfologia do esmalte após o tratamento clareador. O, com ou sem PC, manteve as propriedades mecânicas e físicas de microdureza e micromorfologia da superfície do esmalte, e manteve ou reduziu a rugosidade da superfície, em comparação com o tratamento clareador a base de PC aplicado em moldeira convencional. Conclusões: O tratamento com peróxido de carbamida a 10% para uso em moldeiras promoveu maiores alterações nas propriedades de superfície do esmalte do que aquelas observadas nos tratamentos com ozônio e com peróxido de carbamida ozonizado a 10% para uso em consultório.

The potential of salivary albumin to degrade composite resin.

Albumin is a salivary enzyme capable of cleaving ester linkages and catalyzing degradation of resin-based dental materials. However, the effect of concentration-dependent esterolytic action on composite resins as yet remains unexplored. Aim: The purpose of this study was to evaluate whether artificial saliva formulations with different concentrations of albumin affected the surface roughness, flexural strength and microhardness of a composite resin. Materials and Method: Specimens (25x2x2mm) of a nanofilled composite (Filtek Z350XT, 3M/ESPE) were prepared and analyzed for average surface roughness (Ra/pm). The specimens were then allocated to 6 groups (n=30), to be treated with different salivary albumin concentrations: 0, 10, 50, 100, 200, 400 pg/mL. The specimens were stored in their respective artificial saliva groups, half of them for 24 h and the remainder for 180 days (artificial saliva renewed weekly), after which they were submitted to a new Ra reading, and tested for three-point flexural strength (FS, MPa). The specimens stored for 180 days were analyzed for Knoop microhardness (KH, Kg/mm2). Data were submitted to two-way ANOVA (Ra and FS) and one-way ANOVA (KH). Results: Although Ra increased (p < 0.001) and FS decreased (p < 0.001) from 24 hours to 180 days of storage, the albumin concentration did not significantly affectRa (p = 0.168), FS (p = 0.477) or KH (p = 0.378). Conclusion: The esterolytic action of albumin did not increase the artificial-saliva-induced hydrolytic degradation of the composite resin.

Albumina, uma enzima encontrada na saliva, é capaz de clivar ligagoes éster e catalisar a degradando de materiais dentários á base resina. Apesar da agao esterolítica ser potencialmente concentragao-dependente, a investigando desse efeito sobre resinas compostas ainda permanence inexplorado. Objetivo: O objetivo deste estudo foi avaliar se formulagoes de saliva artificial contendo diferentes concentragoes de albumina afetariam a rugosidade superficial, a resistencia flexural e a microdureza de uma resina composta. Materials e Método: Corpos de pro-va em barra (25x2x2mm) foram confeccionados a partir de uma resina composta nanoparticulada (Filtek Z350XT, 3M/ESPE) e foram submetidos á leitura de rugosidade superficial média inicial (Ra, pm), em rugosímetro. Entao, as amostras foram divididas em 6 grupos (n=30) de acordo com a concentrando de albumina na saliva: 0, 10, 50, 100, 200, 400 pg/mL. As amostras foram armazenadas nas formulagoes de saliva artificial correspondente ao seu grupo, metade por 24 h e as demais por 180 dias (com trocas de saliva semanais). As amostras foram submetidas a no-vas leituras de rugosidade (Rafinal) e avaliadas quanto á resistencia flexural de tres pontos (RF, MPa). As amostras armazenadas por 180 dias foram avaliadas quanto á microdureza Knoop (KH, Kg/mm2). Os dados foram submetidos a análises de variáncia a dois critérios (Ra e RF) e a um critério (KH). Resultados: Apesar de haver aumento na Ra (p < 0,001) e uma diminuigao da RF (p < 0,001) de 24 h para 180 dias, a concentragao de albumina nao afetou significativamente a Ra (p = 0,168), a RF (p = 0,477) ou a KH (p = 0,378). Conclusoes: A agdo esterolítica da albumina nao aumentou a degradagao hidrolítica da resina composta induzida pela saliva artificial.

Fracture load and failure mode of semi-direct resin composite occlusal veneers: Influence of design and mechanical cycling.

AIMS: To evaluate the influence of the type of preparation and mechanical cycling on the fracture load and failure mode of semi-direct posterior resin composite restorations. METHODS: In total, 70 healthy third molars were used; 10 belonging to the control group (C - unprepared teeth) and 60 teeth prepared and restored with nanoparticle resin composite, divided into 3 groups (n = 20): O - exclusively occlusal preparation (Table Top); OV - occlusal preparation with buccal extension (Veneerlay); OVP - Occlusal preparation with chamfer on the proximal and buccal-lingual/palatal surfaces (Overlay). The preparations were performed with diamond burs with a thickness of 1 mm. The restorations were made with nanoparticulate resin composite (Filtek Z350 XT) and subsequently received additional polymerization (thermoprocessing). Cementation was performed with the use of universal adhesive system (Single Bond Universal) on dental substrate and dual resin cement (RelyX ARC). Half of the teeth in each group (n = 10) were submitted to mechanical cycling, simulating 6 months of clinical service (5 × 105 fatigue cycles), under dynamic loading of 130 N, at a frequency of 2Hz. Fracture load tests were performed in a universal testing machine with a 200 kgf load cell. Failure mode was classified using scores. Generalized linear models and Fisher Exact tests were applied to the data (significance level of 5%). RESULTS: There were no significant differences between the types of preparation (p = 0.9435), or relative to cycling (p = 0.3764). The Fisher Exact Test showed a significant association between the groups and the type of failure (p = 0.0006), with preparations O (with cycling) and OVP (with and without cycling) exhibiting most failures with restoration fractures without involvement of the dental remnant. CONCLUSIONS: Semi-direct restorations showed resistance to fracture load similar to that of healthy teeth and were capable of withstanding functional masticatory loads. The type of preparation influenced the failure mode of teeth. The Table Top and Overlay types of preparations were those had fewer catastrophic failures, suggesting that since they are more conservative preparations, they made it possible for the tooth to receive a new restorative procedure in the future in cases of failures.

Continuous vs fractionated violet LED light protocols for dental bleaching: Evaluations of color change and temperature of the dental pulp and buccal surface.

BACKGROUND: Dental color change and the temperature of the pulp chamber and of the buccal surface were evaluated during bleaching with 37% carbamide peroxide (CP) with continuous vs fractionated violet LED light protocols. METHODOLOGY: Bovine incisors received in-office bleaching for 30 min using different light protocols (Bright Max Whitening, MMOptics). Teeth were separated into groups (n = 10): HP) 35% hydrogen peroxide (Whiteness HP, FGM)/no light; CP) 37% carbamide peroxide (Whiteness SuperEndo, FGM)/no light; CP10) CP+10 min of continuous light; CP20) CP+20 min of continuous light; CP30) CP+30 min of continuous light; CPF) CP+20 cycles of 60 s light / 30 s no light (fractionated). Color evaluations were performed at different times. Evaluations of pulp and buccal surface temperatures were performed before and throughout the 30 min of bleaching. RESULTS: Generalized linear models for repeated measures over time were applied to the data (α=5%). After the 1st session, CP20 and CP30 had significantly lower b* values ​​than CP and CP10 (p = 0.0071). For ΔEab and ΔE00, CPF, CP20 and CP30 showed the highest color change among the treatments after the third bleaching (p<0.05). For temperature evaluations, CP30 showed higher pulp and buccal surface temperatures than the other protocols (p<0.0001) after 20 min. CONCLUSION: Fractionated or continuous application of violet LED for 20 or 30 min leads to greater effectiveness of color change. All protocols with the application of LED led to an increase in pulp and buccal surface temperatures during bleaching, although the fractionated application appeared to be safer than the use of continuous light.