Correspondence between try-in pastes and resin cements, and color stability of bonded lithium disilicate disks

Abstract: This study investigates the color correspondence of resin cements and try-in pastes, and the color stability of bonded lithium disilicate ceramic disks. Resin composite disks were fabricated (n = 36) to serve as the background for lithium disilicate disks prepared in two thicknesses (0.5 and 1.0 mm, n = 18 each). Two brands were used for try-in and cement procedures: Variolink Veneer and AllCem Veneer. For baseline, water was applied between the ceramic disks and their respective backgrounds to achieve the control group. This set was subjected to color measurement using an intraoral measurement device (T0). The try-in was inserted between background and ceramic, and this set was subjected to color measurement (T1). After adhesive procedures, the ceramic disk was placed under cement, and color measurement was performed with uncured cement (T2) and 24 h after light-curing (T3). Each set was immersed in distilled water and thermal-cycled, with color measurement being performed after 10,000 (T4) and 20,000 (T5) cycles. Color differences were calculated by CIELab (rEab) and CIEDE2000 (rE00). Data were analyzed by two-way ANOVA for repeated measurements and Tukey's test (α=5%). There was color correspondence of try-in and resin cement for the Variolink system, regardless of the ceramic thickness (p > 0.05). For the AllCem system, the thickness significantly influenced the color measurement (p < 0.001). The Variolink system also demonstrated color stability after 20,000 thermal cycles with rEab < 3.46 and rE00 < 2.25. It was concluded that the color correspondence between a try-in and its respective cement may vary according to resin cement composition.

A comparative leakage study on Er, Cr: YSGG laser- and bur- prepared Class V cavities restored with a low-shrinkage composite using different filling techniques

Aim: To evaluate the leakage on Er,Cr:YSGG laser- and bur- prepared Class V cavities restoredwith a silorane-based composite resin using different insertion techniques Methods: 40 cavitieswere outlined according to: the type of instrument [Er,Cr:YSGG laser (3.0 W power, energy perpulse of 150 mJ, fluence of 53.57J/cm2, pulse duration of 140-200 μs, 20 Hz repetition rate and55/65% air/water spray) or diamond bur]; and the type of filling technique (bulk increment orincremental). Four experimental groups were obtained (n=10): G1- diamond bur (DB) andincremental (I); G2- DB and bulk increment (BI); G3- Er,Cr:YSGG and I; and G4- Er,Cr:YSGGand BI. Specimens were restored with a silorane-based composite resin (Filtek P90, 3M/ESPE),subjected to 500 thermal cycles, sealed, infiltrated with 2% (w/v) methylene blue and sectioned inhalves. Specimen analysis was scored based on a scale. Statistical analyses were done usingthe Kruskal-Wallis and Student Newman-Keuls tests (α=0.05). Results: Statistically significantdifferences were observed between G2 and G4 (p=0.003) and between G1 and G2 (p=0.028).The filling technique did not influence the pattern of dye leakage in the cavity walls (p=0.151).Conclusions: Less leakage was observed when Er,Cr:YSGG cavities were restored withsilorane-based composite resin, using the bulk increment technique. Nevertheless, cavities doneusing diamond bur have less leakage only when incrementally restored.

Microtensile bond strength of enamel after bleaching.

Objective: To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Materials and Methods: Twenty bovine teeth were randomly distributed into 4 groups (n = 5), 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control); G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm) area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min) 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM). Results: There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2). There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive) failure in all groups. Conclusion: The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

Benefícios dos lasers de alta e baixa potência no procedimento restaurador direto: relato de caso / Benefits of low and high power lasers on direct restorative procedures: a case report

Lasers de alta e baixa potência têm sido amplamente utilizados em diversas especialidadesda Odontologia. Na Dentística, podem ser utilizados em diferentes etapas do procedimento restaurador direto, como na remoção seletiva do tecido cariado e redução de sensibilidade pós¬preparo cavitário. Este artigo tem como objetivo apresentar um relato de caso em que diferentes lasers foram utilizados e discutir, baseado em resultados de estudos já publicados na literatura, os benefícios de cada um deles quando associados ao procedimento convencional.

High and low power lasers have been widely used in different specialties of Dentistry. InRestorative Dentistry, it can be used in different steps of the direct restorative procedure, as for the selectively remova I of caries tissue and for the reduction of tooth sensitivity following cavity preparation. This article aims to present a case report in which different lasers were used and discuss, based on results of studies already published in the literature, the benefits of each laser when associated with conventional procedures.

Pré-tratamento da superfície de esmalte bovino (Flúor, CPP-ACP, Laser Nd: YAG + Flúor) antes de um clareamento de consultório. Efeitos sobre a morfologia, a microdureza e a cor do esmalte / Pre-treatment of the surface of bovine enamel (fluoride, CPP-ACP, and Nd: YAG laser + fluoride) before an office whitening. Effects on morphology, microhardness and color enamel

o clareamento dental oferece uma opção de tratamento conservador, seguro e eficiente para aqueles pacientes insatisfeitos com a cor dos seus dentes. Entretanto, o baixo pH inicial dos agentes clareadores pode causar perda de estrutura levando à alteração na microdureza e na morfologia do esmalte. O objetivo deste trabalho foi verificar a influência dos pré-tratamentos da superfície de esmalte dental bovino com Flúor, CPP-ACP ou laser de Nd:YAG associado ao flúor realizados 24 horas antes do clareamento de consultório, avaliando-se: a morfologia, a microdureza e a alteração de cor do esmalte dental. Sessenta e quatro incisivos bovinos foram preparados de acordo com a análise para a qual eles foram submetidos. Quatro dentes foram preparados para MEV, vinte dentes para a microdureza e quarenta dentes para a análise de cor. Todos eles tiveram suas raízes removidas a 2 mm do limite amelodentinário e blocos de esmalte foram cortados e depois planificados e polidos com lixas de carbureto de silício de granulação decrescente (#400, 600, 1200 e 4000). Após o polimento, os blocos de esmalte foram submetidos aos pré-tratamentos de superfície com flúor, CPP-ACP e laser de Nd:YAG associado ao flúor e 24 horas depois eles foram clareados com peróxido de hidrogênio a 35% conforme técnica de clareamento de consultório. A avaliação do esmalte dental bovino submetido à ação do clareamento quanto à microdureza e à alteração de cor, foi realizada através do microdurômetro e espectrofotômetro, respectivamente no início e após o clareamento. Uma leitura intermediária foi feita imediatamente após os pré-tratamentos de superfície de esmalte e outra imediatamente após o clareamento. Duas amostras de cada grupo (n=2) foram confeccionadas para a Microscopia Eletrônica de Varredura para observação da morfologia da superfície do esmalte. Quanto à microdureza os seguintes resultados foram encontrados: G1

The bleaching offers a conservative, safe and effective for patients dissatisfied with color of your teeth. However, the low initial pH of bleaching agents can cause loss of structure leading to change in morphology, microhardness of enamel. The aim of this study was to assess the influence of pre-treatments on surface of bovine enamel with fluoride, CPP-ACP or laser Nd: YAG laser associated with fluoride applied 24 h before the whitening, dental evaluating: morphology, microhardness and color change of enamel. Sixty-four bovine incisors were prepared according to analysis for which they were submiUed. Four teeth were prepared for morphologic analysis, twenty teeth were prepared for microhardness and forty teeth were prepared for analyze color change. They ali had their roots removed 2 mm dentinoenamel junction and enamel blocks were cut and then planned and polished with silicon carbide abrasive paper of decreasing grain (# 400, 600, 1200 and 4000). After polishing, the enamel blocks were subjected to surface treatment with fluoride, CPP-ACP and laser Nd: YAG laser associated with fluoride and after 24 h they were bleached with hydrogen peroxide 35% as bleaching technique office. Evaluation of bovine enamel subjected to action of bleaching on microhardness and color change was accomplished through the microhardness tester and spectrophotometer, respectively, before and after bleaching. An intermediate reading was made immediately after the pretreatment of enamel surface. Another reading was made immediately after bleaching. Two especimes of each group (n = 2) were prepared for scanning electron microscopy to morphology of enamel surface. The microhardness of following results were found: G1 - 287.7± 25.78; 279.70 ± 21.04; 206.20 ± 13.14; 242.30 ± 19.28; G2 - 260.90 ± 17.57; 269.40 ± 29.74; 248.80 ± 30.33; 260.40 ± 24.41; G3 - 274.40 ± 38.29; 275.90 ± 33.94; 245.90 ±

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