Influence of Preparation Reconstruction on the Compressive Strength of CAD/CAM Ceramic Inlays.

The aim of this study was to evaluate whether the compressive strength of lithium dissilicate ceramic inlays is influenced by the substrate (dentin or composite resin build-up) and to compare it to nonrestored teeth. Thirty freshly extracted human maxillary third molars were selected and randomly ascribed to three groups (n=10). Standardized Class II MOD preparations were made (bucco-palatal width = 2/3 of the intercuspal width and 2/3 of the width at the tooth equator for the proximal boxes), varying the extension of the preparations (Group 2: preparation limited to tooth structure; Group 3: pulpal floor of the preparation rebuilt with composite resin, IPS Empress Direct, restored with lithium dissilicate CAD/CAM ceramic inlays (e.max CAD) and cemented with a resin cement (Variolink II)). All groups were subjected to compressive strength test (1mm/min crosshead speed). The results showed that the fracture strength of G1 (control group) was significantly higher than G2 and G3, while within these groups there were no statistically significant differences. Both groups restored with lithium dissilicate restorations did not reach the fracture strength of the sound teeth but were statistically equivalent and sufficient to withstand physiologic masticatory forces.

Evaluation of the fracture resistance of premolars with extensive and medium cavity preparations restored with direct restoring systems.

CONTEXT: Studies have been conducted to measure the fracture resistance of restored teeth with the current restorative materials. However, most of those studies disregard the cavity size as an influencing variable. AIMS: To evaluate the fracture resistance of prepared and restored maxillary premolars with medium and large preparations. MATERIALS AND METHODS: Seventy superior and sound premolars were randomly divided: G1 (control) - sound tooth; G2, G3, and G4 received a Class II mesial-occlusal-distal (MOD) preparation with an occlusal box width 1/3 of the intercuspal distance, and were restored with Filtek Z350 XT, IPS Empress Direct, and Charisma Diamond, respectively; G5, G6, and G7 received a Class II MOD preparation with an occlusal box width 2/3 of the intercuspal distance, and were restored with Filtek Z350 XT, IPS Empress Direct, and Charisma Diamond, respectively. After storage in water, at 37°C, the specimens were subjected to a fracture test under compression in a universal testing machine where the loads were applied vertically and at a speed of 0.5 mm/min. STATISTICAL ANALYSIS USED: Data were analyzed with two-way ANOVA and Tukey's multiple comparison post hoc test (P < 0.05). RESULTS: G1 presented a fracture resistance significantly higher (P = 0.005) than any other experimental groups. Among the experimental groups, only G5 showed a significantly low fracture resistance (P = 0.019) when compared to the other groups. For the other resins, the change in intercuspal distance from 1/3 to 2/3 the intercuspal distance did not significantly reduce the fracture resistance (P > 0.05). CONCLUSIONS: The cavity preparation weakens the remaining tooth structure; however, its resistance could be partially restored using direct adhesive restorations.

Light irradiance through novel CAD-CAM block materials and degree of conversion of composite cements.

OBJECTIVE: To assess light irradiance (LI) delivered by two light-curing units (LCU's) and to measure the degree of conversion (DC) of three composite cements, when cured through different thicknesses of two novel CAD-CAM block materials. METHODS: 100-µm-thick films of a dual-curable composite cement (G-CEM LinkAce, GC), a light-curable flowable resin-based composite (RBC) (G-ænial Universal Flo, GC) and a micro-hybrid RBC (G-ænial Posterior, GC) were investigated as luting agents. Two 'polymer-ceramic' CAD-CAM blocks (Cerasmart, GC; Enamic, Vita Zahnfabrik) were sectioned in slabs with different thicknesses (1, 3 and 5mm). LI at the bottom of the specimens was measured using a calibrated spectrometer, while being light-cured through the CAD-CAM block slabs for 40s with a low- (±500mW/cm2) or high- (±1,600mW/cm2) irradiance LCU (n=5). After light-curing, micro-Raman spectra of the composite films were acquired to determine DC at 5min, 10min, 1h and 24h. LI data were statistically analyzed by Kruskal-Wallis followed by post-hoc comparisons, while a linear mixed-effect model was applied for the DC analysis. In addition, the CAD-CAM blocks ultrastructure was characterized upon argon-ion slicing using scanning transmission electron microscopy (STEM). Finally, light transmission (LT) through each CAD-CAM block material was assessed using a spectrophotometer. RESULTS: Curing-light attenuation and DC were significantly influenced by thickness and type of the overlying material. LCU only had a significant effect on DC of the micro-hybrid RBC. DC significantly increased over time for all composite cements. CAD-CAM block structural analysis revealed a relatively small and homogenous filler configuration (mean filler size of 0.2-0.5µm) for Cerasmart, while Enamic contained ceramic grains varying in shape and size (1-10µm), which were interconnected by the polymer-based network. LT was much higher at a wavelength range of 300-800nm for Cerasmart than for Enamic. SIGNIFICANCE: Light-curable composite cements can be cured through a restoration up to 2.7-mm thickness, depending on the kind of CAD-CAM material. A high-irradiance LCU only has a limited effect on the maximum thickness of the polymer-ceramic CAD-CAM material that can be cured through.

Evaluation of a technique for color correction in restoring anterior teeth.

OBJECTIVE: This study aimed to evaluate the ability of the proposed technique in producing restorations that exhibit mimesis with tooth structure and to define a restorative clinical protocol. MATERIALS AND METHODS: For this study a typodont was used. The right upper central incisor with Class IV lesion was restored with the layering technique (reference tooth, RT). For the left upper central incisor with Class IV lesion, six teeth were restored monochromatically (test teeth, TT), using DA3.5 (n = 3) and DA4 (n = 3) composite resins-resulting in six unsatisfactory color restorations. TT were divided into six groups depending on the color of unsatisfactory restoration and preparation depth. First, a preparation was realized on the labial surface with 0.5 mm, 0.7 mm or 1.0 mm of depth. A second preparation was then performed to reproduce the dentinal mamelons. Next, adhesive procedures were performed and the teeth restored. Opaque halo, opalescent halo and vestibular enamel were then reproduced by the addition of different composite resins. The RT and TT were photographed side by side in typodont to obtain six photographic prints. The photographs of the groups were subjected to visual evaluation by 120 volunteers via a questionnaire. Data were analyzed by the prevalence of answers, and Chi-square test was used to investigate the association between variables at .05 significance. Furthermore, ΔE of groups was evaluated in comparison RT. RESULTS: The results demonstrated that the moderate intensity restorations (DA3.5) with depths of 0.5 mm and 0.7 mm had the highest prevalence of acceptance. For severe intensity restorations (DA4), the preparation depth of 1.0 mm obtained better acceptance. CONCLUSIONS: The technique was able to modify the final color of Class IV restorations, producing satisfactory color restorations. CLINICAL SIGNIFICANCE: This technique can be used for color correction in cases of Class IV restorations, in situations where there is no time for immediate layered restoration, and as a restorative technique.

Biomechanical behavior of endodontically treated premolars using different preparation designs and CAD/CAM materials.

OBJECTIVES: To evaluate the effect of restoration design ('2.5-mm deep endocrown', '5-mm deep endocrown' or '5-mm deep post&crown') and CAD/CAM material type (composite or lithium disilicate glass-ceramic) on the load-to-failure of endodontically treated premolars in absence of any ferrule. METHODS: The crowns of 48 single-rooted premolars were cut and the roots were endodontically treated. Teeth were randomly divided into six groups (n=8); teeth in each group were restored using one of the two tested materials with standardized CAD/CAM fabricated endocrowns (with either 2.5-mm or 5-mm deep intra-radicular extension) or conventional crowns (5-mm deep post&crown). After cementation using luting composite, the specimens were immersed in distilled water and subjected to 1,200,000 chewing cycles with a load of 50N applied parallel to the long axis of the tooth (0°). After cyclic loading, a compressive load was applied at 45° to the tooth's long axis using a universal testing machine until failure. Load-to-failure was recorded (N) and the specimens were examined under a stereomicroscope with 3.5x magnification to determine the mode of failure. RESULTS: All specimens survived the 1,200,000 chewing cycles. A significant interaction between restoration design and CAD/CAM material was found using two-way ANOVA. In the '2.5-mm deep endocrown' groups, the composite achieved a significantly higher load-to-failure than the lithium disilicate glass-ceramic, while no differences between materials were found in the '5-mm deep endocrown' and '5-mm deep post&crown' groups. More unfavorable failures (root fractures) were observed for higher load-to-failure values. CONCLUSIONS: Only following a '2.5-mm deep endocrown' design, composite appeared more favorable than lithium disilicate glass-ceramic as crown material; this may be explained by their difference in elastic modulus. CLINICAL SIGNIFICANCE: Shallow endocrown preparations on premolars present less surface for adhesive luting and a difference in crown material becomes apparent in terms of load-to-failure. The use of a more flexible composite crown material appeared then a better option.

In Vitro Fatigue Resistance of Teeth Restored With Bulk Fill versus Conventional Composite Resin.

The aim of this study was to compare the fatigue resistance of restored teeth with bulk fill composite resin, conventional composite resin with incremental insertion and unprepared sound teeth. Twenty-eight extracted maxillary premolars were selected and divided into 4 groups based on composite resin and insertion technique: control (C), conventional composite resin with incremental insertion (I) and bulk fill composite resin with three (BF3) or single increment (BF1). The restored specimens were submitted to fatigue resistance test with a 5 Hz frequency. An initial application of 5,000 sinusoidal load cycles with a minimum force of 50 N and a maximum force of 200 N was used. Next, were applied stages of 30,000 load cycles with the maximum force increasing gradually: 400, 600, 800, 1000, 1200 and 1400 N. The test was concluded when 185,000 load cycles were achieved or the specimen failed. The fatigue resistance data were recorded for comparison, using the Kaplan-Meier survival curve and analyzed by log-rank test at 0.05 significance. Fractures were classified based on the position of the failure - above or below the cementoenamel junction (CEJ). Statistical analysis of the Kaplan-Meier survival curve and log-rank test showed a significant difference between groups (p=0.001). The fracture analysis demonstrated that only 28.58% of failures were below the CEJ in group C, while for groups I, BF1 and BF3 they were 42.85%, 85.71% and 85.71%, respectively. Teeth restored with composite bulk fill in both techniques present similar fatigue resistance values compared with those restored with a conventional incremental insertion of composite, while the fatigue strength values of unprepared sound teeth were higher. Furthermore, unprepared sound teeth showed a lower percentage of fractures below the CEJ.

In Vitro Fatigue Resistance of Teeth Restored With Bulk Fill versus Conventional Composite Resin

Abstract The aim of this study was to compare the fatigue resistance of restored teeth with bulk fill composite resin, conventional composite resin with incremental insertion and unprepared sound teeth. Twenty-eight extracted maxillary premolars were selected and divided into 4 groups based on composite resin and insertion technique: control (C), conventional composite resin with incremental insertion (I) and bulk fill composite resin with three (BF3) or single increment (BF1). The restored specimens were submitted to fatigue resistance test with a 5 Hz frequency. An initial application of 5,000 sinusoidal load cycles with a minimum force of 50 N and a maximum force of 200 N was used. Next, were applied stages of 30,000 load cycles with the maximum force increasing gradually: 400, 600, 800, 1000, 1200 and 1400 N. The test was concluded when 185,000 load cycles were achieved or the specimen failed. The fatigue resistance data were recorded for comparison, using the Kaplan-Meier survival curve and analyzed by log-rank test at 0.05 significance. Fractures were classified based on the position of the failure - above or below the cementoenamel junction (CEJ). Statistical analysis of the Kaplan-Meier survival curve and log-rank test showed a significant difference between groups (p=0.001). The fracture analysis demonstrated that only 28.58% of failures were below the CEJ in group C, while for groups I, BF1 and BF3 they were 42.85%, 85.71% and 85.71%, respectively. Teeth restored with composite bulk fill in both techniques present similar fatigue resistance values compared with those restored with a conventional incremental insertion of composite, while the fatigue strength values of unprepared sound teeth were higher. Furthermore, unprepared sound teeth showed a lower percentage of fractures below the CEJ.

Resumo O objetivo deste estudo foi comparar a resistência à fadiga de dentes restaurados com uma resina composta bulk fill, resina composta convencional de inserção incremental e dentes hígidos sem preparo. Vinte e oito pré-molares maxilares extraídos foram selecionados e divididos em quatro grupos conforme a resina composta e técnica de inserção: controle (C), resina composta convencional com inserção incremental (I) e resina composta bulk fill inserida em três (BF3) ou único incremento (BF1). O preparo das cavidades foi padronizado para todos os grupos. As amostras foram restauradas e submetidas ao testes de resistência à fadiga com uma frequência de 5 Hz. Foram aplicados 5.000 ciclos de carregamento senoidal inicial com valor de força mínima igual a 50 N e força máxima de 200 N. Após, foram aplicados estágios de 30.000 ciclos de carga com a força máxima sendo aumentada gradativamente a cada estágio, para 400, 600, 800, 1000, 1200 e 1400 N. O ensaio foi finalizado ao ser alcançado 185.000 ciclos de carga (número máximo de ciclos de carga), ou na fratura da amostra. A resistência à fadiga foi registrada para comparação usando a curva de sobrevivência de Kaplan-Meier e analisada pelo teste log-rank a um nível de significância de 0.05. As fraturas foram classificadas conforme a posição da falha - acima ou abaixo da junção cemento esmalte (JCE). A análise estatística da curva de sobrevivência de Kaplan-Meier pelo teste log-rank demonstrou diferença significativa entre os grupos (p=0.001). Na análise de fratura somente 28.58% das falhas foram abaixo da JCE para o grupo C, enquanto para os grupos I, BF1 e BF3 foram 42.85%, 85.71% e 85.71%, respectivamente. Os dentes restaurados com a resina composta bulk fill em ambas as técnicas de inserção apresentaram valores de resistência à fadiga similares àqueles dos dentes restaurados com a resina composta convencional pela técnica incremental. Entretanto, dentes hígidos mostraram uma menor porcentagem de fraturas abaixo da JCE e maior resistência à fadiga.

Evaluation of microtensile bond strength of self-etching adhesives on normal and caries-affected dentin.

The purpose of this study was to evaluate the µTBS (microtensile bond strength) of currently available self-etching adhesives with an experimental self-etch adhesive in normal and caries-affected dentin, using a portable hardness measuring device, in order to standardize dentin Knoop hardness. Normal (ND) and caries-affected dentin (CAD) were obtained from twenty human molars with class II natural caries. The following adhesive systems were tested: Mega Bond (MB), a 2-step self-etching adhesive; MTB-200 (MTB), an experimental 1-step self-etching adhesive (1-SEA), and two commercially available one-step self-etching systems, G-Bond Plus (GB) and Adper Easy Bond (EB). MB-ND achieved the highest µTBS (p<0.05). The mean µTBS was statistically lower in CAD than in ND for all adhesives tested (p<0.05), and the 2-step self-etch adhesive achieved better overall performance than the 1-step self-etch adhesives.

Shear bond strength of ceramic brackets after different pre-treatments in porcelain surface

To evaluate the bond strength of brackets bonded after different surface treatments on two dental ceramics. METHODS: One hundred and twenty discs 5 mm thick and 7 mm diameter of two ceramic types were made and randomly divided in 8 groups. Groups 1, 3, 5, and 7 used Eris ceramic and groups 2, 4, 6, and 8 used d.Sign ceramic. The ceramic surfaces were treated with 10% hydrofluoric acid G1 and G2, 10% hydrofluoric acid + silane G3 and G4, aluminum oxide blasting + 35% phosphoric acid + silane G5 and G6, CoJet blasting + 35% phosphoric acid + silane G7 and G8. Metallic brackets were cemented with Concise cement. Mechanical test was performed in a universal testing machine until failure. RESULTS: The average values MPa obtained G1 - 7.30; G2 - 6.12; G3 - 17.49; G4 - 19.54; G5 - 18.80; G6 - 21.93; G7 - 6.81 e G8 - 9.77 were submitted to ANOVA and Tukey test p<0.05. The fracture patterns were analyzed in stereoscopic microscope 25´X and representative samples of each group were analyzed in SEM. CONCLUSIONS: It was possible to conclude that use of silane after hydrofluoric acid increased the bond strength values...

Restauração Classe IV: estratificação natural com resina composta / Class IV restorations: natural stratification with composite resin

Restaurar apenas um dente anterior fraturado é um desafio para a Odontologia Estética, em função do restabelecimento da forma e da cor, necessárias para a reprodução fiel das características do dente natural. Este artigo apresenta algumas estratégias para facilitar o planejamento e a execução de uma restauração Classe IV no incisivo central superior com resina composta nanoparticulada, mediante o uso de um mapa cromático com a seleção das cores, seguido de um ensaio restaurador. Passados 5 dias, o ensaio foi avaliado e realizada a restauração definitiva. As etapas de acabamento, polimento e texturização foram conduzidas para mimetizar a estrutura dental...

Restoration of a single anterior fractured tooth is a challenge in aesthetic dentistry, since it is difficult to reestablish form and color, necessary for the accurate reproduction of the features present in natural teeth. This article presents some strategies facilitating the planning and execution of a Class IV restoration in the maxillary central incisor with nanoparticle composites through the use of a chromatic map, followed by a mock-up. After 15 days, the assay was evaluated and the definitive restoration was fabricated, followed by the final finishing, polishing and texturing to mimic the tooth structure...

Marginal and internal fit of four-unit zirconia fixed dental prostheses based on digital and conventional impression techniques.

OBJECTIVES: The aim of this in vitro study was to evaluate the marginal and internal fit of CAD/CAM-generated four-unit zirconia fixed dental prostheses made with digital and conventional impressions. MATERIALS AND METHOD: A titanium master model was used. For group conventional impression (CI), 12 polyether impressions of the master model with Impregum(TM) were made. For group digital impression (DI), 12 digital impressions of the master model using Lava(TM) C.O.S. system were made. The replica technique was applied. The Mann-Whitney U statistical test was applied to detect statistical differences between the groups, in terms of marginal and internal fit. Face-by-face comparisons between groups were also carried out. RESULTS: Groups DI and CI presented mean marginal fit of 63.96 and 65.33 µm, respectively, and showed no statistically significant difference. Groups DI and CI presented significantly different internal fit with mean values of 58.46 and 65.94 µm, respectively. Group DI showed statistically significantly lower values for marginal and internal fit on premolar mesial face, and on molar distal and palatal faces. CONCLUSIONS: Frameworks fabricated from digital and conventional impressions showed clinically acceptable marginal fit. Frameworks fabricated from digital impression demonstrated better internal fit than ones fabricated from conventional impression. Reviewing each retainer face, digital impression showed better marginal and internal fit at the premolar mesial and molar distal faces. CLINICAL RELEVANCE: The results of this in vitro study show that digital impressions made with the Lava(TM) C.O.S. system and its digital workflow are suitable for fabricating four-unit zirconia frameworks, with regard to marginal and internal fit requirements.

Does operatory field isolation influence the performance of direct adhesive restorations?

PURPOSE: To evaluate the influence of different adhesive strategies (etch-and-rinse and self-etching adhesives) and type of field isolation (absolute or relative) on the clinical performance of restorations of noncervical carious lesions (NCCLs). MATERIALS AND METHODS: One hundred forty NCCLs were selected from 38 patients, according to previously established inclusion/exclusion criteria, and assigned to one of four groups (n = 35): etch-and-rinse/rubber-dam (ERR), etch-and-rinse/cotton roll (ERC), self-etching/rubber-dam (SER) and self-etching/cotton roll (SEC). The adhesive systems used were: Adper Single Bond 2 (3M ESPE) and Adper SE Plus (3M ESPE), with restorations made using a composite resin (Z350, 3M ESPE). Using the USPHS modified criteria, 140 restorations were evaluated by two calibrated examiners at 5 different times: immediately after placement, at 7 days, and 2, 6, and 12 months. In order to evaluate the presence of gingival recession after the use of the #212 rubber-dam clamp, the clinical crowns of the teeth from groups ERR and SER were measured at six different periods (baseline, immediately, and at 7 days, 2, 6, and 12 months). Data were subjected to McNemar's, chi-square, and Student's t-tests. RESULTS: Both adhesive strategies reduced tooth sensitivity beyond the second period of evaluation (7 days); tooth sensitivity disappeared after the third period of evaluation (2 months). There were no statistically significant differences between the adhesive techniques or isolation techniques, except for a Bravo score for marginal discoloration in group SEC at 6 months, which was significantly different from the other groups. The rubber-dam isolation technique was more uncomfortable for the patient and resulted in short-term gingival recession. CONCLUSION: No significant differences were found between the types of isolation or adhesive strategy in this clinical evaluation, with the exception of 2 restorations in group SEC that showed marginal discoloration, possibly due to inadequate enamel etching by the self-etching adhesive. Class V restorations perform equally well placed with or without rubber-dam.

Efeito da desproteinização na adesão à dentina intrarradicular / The effect of deproteinization on adhesion to root dentin

O presente estudo in vitro avalia o efeito do tratamento da dentina intrarradicular com hipoclorito de sódio a 1%, após condicionamento ácido, na retenção de pinos fibrorresinosos intrarradiculares. Os dentes selecionados tiveram a porção coronal removida e o tratamento endodôntico realizado. Os espaços para os pinos foram preparados, e os pinos, cimentados com cimento resinoso e adesivo. Os dentes foram seccionados e submetidos ao teste de cisalhamento por extrusão, em dois grupos: controle (1) com o cimento utilizado de acordo com o fabricante (condicionamento ácido total seguido do adesivo) e experimental (2), com a aplicação hipoclorito de sódio a 1% na dentina condicionada previamente à aplicação do sistema cimentante. Os resultados demonstram que o tratamento alternativo com hipoclorito de sódio utilizado diminui a retenção de pinos fibrorresinosos à dentina intrarradicular.

This in vitro study evaluated the effect of treatment of intraradicular dentin with 1% sodium hypochlorite after acid etching on the retention of fiber posts. After removing the coronal portion, all teeth were endodontically treated and dowel spaces were prepared using post drills provided by the manufacturer and fiber posts were cemented with resin cements and adhesive. The teeth were sectioned and subjected to shear stress by extrusion into 2 groups: (1) control – cement used in accordance with the manufacturer (total acid etching followed by the adhesive) and (2) experimental – application of 1% sodium hypochloride to conditioned dentin prior to the application of the cement system. The results demonstrate that the alternative treatment with sodium hypochlorite decreased the retention of fiber posts.

Clinical performance of cervical restorations with desensitizing agents: 18-month clinical trial.

PURPOSE: To evaluate the clinical performance and postoperative sensitivity of noncarious Class V restorations with and without the use of a potassium oxalate-based desensitizing agent over a period of 18 months. MATERIALS AND METHODS: One hundred forty cervical lesions (40 patients) were selected and randomly divided into four groups: group 1 (G1) - teeth restored with the application of a potassium oxalate-based desensitizing agent (BisBlock) after acid etching and before the application of the adhesive Adper Single Bond 2; group 2 (G2) - teeth restored using the same adhesive system used in G1, without the use of any desensitizing agent; group 3 (G3) - similar to G1, but using the adhesive One-Step; group 4 (G4) - similar to G3, but without the application of BisBlock. All restorations were evaluated (double blind) after 1 week and 2, 6, 12, and 18 months according to the modified USPHS criteria. The McNemar and chi-square tests were used to analyze the results (p ≤ 0.05). RESULTS: There were no statistical differences between groups restored with or without the use of a desensitizing agent for postoperative sensitvity. After 18 months, retention rates proved to be statistically significantly lower for One-Step than Adper Single Bond 2. CONCLUSION: The use of potassium oxalate-based desensitizing agent did not decrease postoperative sensitivity when it was used under composite resin restorations.

Avaliação da microdureza superficial de uma resina composta fotopolimerizável em função da utilização de luvas contaminadas durante o ato restaurador / Superficial microhardness evaluation of a photopolymerizable composite resin for the use of contaminated gloves during the restorative act

A manipulação inadequada de resinas compostas fotopolimerizáveis para a inserção nas cavidades, tocando o material restaurador com luvas utilizadas desde o início da sessão operatória, tem sido utilizada. Este trabalho teve como objetivo comparar a dureza superficial de uma resina composta micro-híbrida, Charisma Heraeus Kulzer, manipulada com luvas contaminadas durante o ato restaurador. Foram utilizados 40 cilindros de 3cm de diâmetro por 3cm de altura, confeccionados em matriz de aço inoxidável. No Grupo LC, os cilindros foram obtidos com a manipulação de luvas contaminadas. Grupo LCL, igualmente ao Grupo LC, as luvas foram limpas com esfregaço de álcool a 70% durante um minuto. No Grupo LNC, utilizaram-se luvas descontaminadas. E no Grupo E, utilizou-se espátula. Os grupos receberam incrementos de 2 mm cada e foram fotopolimerizados por 1 minuto e 40 segundos com aparelho Curing Light 2.500 (3M Espe), com intensidade luminosa de 500 mW/cm(2) acondicionados em um frasco à prova de luz com água deionizada e mantidos em uma estufa a 37ºC. Após 24 horas, os cilindros foram incluídos em resina epóxica polidos em politriz com lixa d'água e pastas diamantadas. O teste de dureza Knoop foi realizado no microdurômetro após uma semana, com carga estática de 25 g por 15 segundos em seis regiões aleatórias.

Os resultados foram analisados pelos testes estatísticos ANOVA e Tukey. As médias de dureza Knoop foram: Grupo LC: 65,61; Grupo LCL: 61,24; Grupo LNC: 83,23; Grupo E: 83,82. Houve diferença estatisticamente significante entre os grupos manipulados com espátula e luva descontaminada, os quais apresentaram maior dureza em relação aos grupos com luvas contaminadas e luvas contaminadas limpas com álcool

Effect of multiple coats of ultra-mild all-in-one adhesives on bond strength to dentin covered with two different smear layer thicknesses.

PURPOSE: To evaluate the effect on bond strength of 1, 2, or 3 coats of two one-step self-etching adhesives on dentin covered with two different smear layer thicknesses. MATERIALS AND METHODS: Flat dentin surfaces from recently extracted third molars were wet ground with 60- or 600-grit SiC paper to produce smear layers of different thicknesses. Adper Easy Bond (3M ESPE) and Clearfil S3 Bond (Kuraray) were applied in 1, 2, or 3 consecutive coats after air drying each coat. ScotchBond Multi Purpose (3M) and Clearfil SE Bond (Kuraray) were used as controls. Composite resin crowns (Filtek Z250, 3M ESPE) were built up, stored for 24 h, and cut in x and y directions. Eight to twelve sticks (0.65 ± 0.05 mm2 of area) from the central area of each tooth were fractured in tension (0.5 mm/min). Sticks from each group were processed for interfacial micromorphological evaluation with SEM. RESULTS: Three-way ANOVA revealed a significant interaction between factors (p < 0.05). Tukey's post-hoc test showed that only when Adper Easy Bond was applied on dentin prepared with 600-grit SiC paper, microtensile bond strength was not significantly affected by the number of coatings. However, the effect of smear layer thickness was only statistically significant when the adhesives were applied in one coat, for both adhesives. When they were applied in two or three coats, smear layer thickness did not significantly affect bond strength (p > 0.05). CONCLUSIONS: The thickness of the smear layer affected the bond strength of both all-in-one adhesives. Additional coats can be beneficial to bond strength, especially with Clearfil S3 Bond.

Cimentos auto-adesivos: revisão da literatura ilustrada com caso clínico / Self-adhesive cements: literature review and case report

Este trabalho reúne informações científicas sobre o emprego dos cimentos auto-adesivos e as discute criticamente, em busca de subsídios para o uso seguro desse agente cimentante. A investigação buscou artigos científicos que abrangem assuntos relacionados com adesão, microinfiltração e biocompatibilidade. Adicionalmente, relata um caso clínico que exibe sua técnica para cimentação de coroas de porcelana pura. Apenas um cimento auto-adesivo disponível comercialmente tem seu emprego analisado por vasta literatura. Constata que seu uso é excelente alternativa para a cimentação de restaurações indiretas, no entanto, o condicionamento prévio do esmalte melhora sua interação com esse tecido

The aim of this work was to gather and to discuss scientific information regarding the safe use of self-adhesive cements. The terms “luting”, “microleakage” and “biocompatibility” were searched. A case report of an all-ceramic crown using a self-adhesive cement is presented. There is only commercially available self-adhesive cement which has been extensively reviewed and researched, and its has been suggest that it is an excellent alternative for luting indirect restorations, provided that selective etching of enamel is performed to improve its performance

Resinas compostas para esmalte clareado podem diminuir a luminosidade do substrato nas técnicas restauradoras estratificadas / Marginal integrity analysis through three-dimensional scanner in silorane-based composites

Por meio de análise espectrofotométrica, este estudo avaliou a influência cromática de resinas compostas para esmalte clareado em substrato de resina composta para dentina A2. Sessenta e cinco corpos de prova foram confeccionados e divididos em um grupo controle (GC) e quatro grupos teste (G+cor da resina), da seguinte forma: a) GC, formado por resina para dentina (n=5); b) GXXL, formado por resina para dentina e resina para esmalte clareado XXL (n=15); c) GXL, formado por resina para dentina e resina para esmalte clareado XL (n=15); d) GL, formado por resina para dentina e resina para esmalte clareado L (n=15); e) GM, formado por resina para dentina e resina para esmalte clareado M (n=15). O incremento de resina para dentina acrescentou a espessura única de 2mm, enquanto o incremento de resina para esmalte clareado apresentou três diferentes espessuras, originando, em cada grupo teste, três subgrupos (S): a) S1, 1,2mm; b) S2, 0,8mm; c) S3, 0,4mm. A análise estatística foi realizada com ANOVA, que revelou diferenças significantes na luminosidade dos corpos de prova, conforme demonstrado por comparações feitas por meio do teste de Dunnett. Das quatro resinas para esmalte avaliadas apenas uma elevou a luminosidade do substrato. A aplicação dessas resinas provocou, em todos os grupos teste, alterações cromáticas consideradas clinicamente inaceitáveis (∆3>3,3).

The aim of this study was to perform a spectrophotometric analysis of chromatic influence of composite resins for bleached enamel on a A2-shaded composite resin substrate. Sixty five specimens were distributed in a Control Group (GC = dentin composite resin) and four test groups (GC + enamel composite shade) as following: a) GC, A2 shaded dentin composite resin (n=5); b) GXXL. GC and a composite for bleached enamel (XXL) (n=15); c) GXL, GC and a composite for bleached enamel (XL) (n=15); d ) GL, GC and a composite for bleached enamel (L) (n=15); e) GM, GC and a composite for bleached enamel (M) (n=15). The thickness of the dentin composite was 2,0mm, while the enamel composite presented three different thicknesses, originating three subgroups for each group (1.2mm, 0.8mm, and 0.4mm, i.e., S1, S2, and S3, respectively). Two-way ANOVA and Dunnett’s test for individual comparisons revealed statistically significant differences for luminosity. Only enamel composite increased the substrate luminosity. The application of bleached enamel composite resins resulted in clinically unacceptable chromatic changes in all test groups (Δ3>3.3).

Post-etching cleaning and resin/ceramic bonding: microtensile bond strength and EDX analysis.

PURPOSE: The aim of this study was to evaluate the microtensile bond strength of a resin composite bonded to two heat-pressed ceramics after performing different post-etching cleaning techniques. MATERIALS AND METHODS: Resin composite specimens were bonded to IPS Empress Esthetic (EE) and IPS Empress 2 (E2) heat-pressed ceramic disks after etching with 10% HF, surface cleaning, silanization and application of an unfilled hydrophobic resin. Resin composite specimens were fabricated using 4-mm (height) Tygon tubes of 0.8 mm diameter and bonded according to the post-etching cleaning technique employed (n = 30): no cleaning (NC); air-water spray for 30 s (AWS); 37% phosphoric acid etching for 30 s (PA); ultrasonic bath in distilled water for 5 min (UB); PA + UB (PAUB); application of a self-etching silane/bonding system Clearfil Silane Kit (CSK). The resin composite specimens were subjected to tensile tension at a crosshead speed of 0.5 mm/min. SEM observation and EDX analysis were performed for each group to determine elemental distribution in the samples. RESULTS: Two-way ANOVA with random effect showed statistically differences between subgroups for E2, in which E2NC only showed bond strength significantly lower than E2AWS and E2BU, as indicated by Student's t-test and a contrast method. For EE, subgroups EENC and EECSK groups showed statistically significant differences between each other and among the other post-etching cleaning technique groups (p < 0.05). CONCLUSION: Air-water spray may be used as a post-etching cleaning technique for both ceramics. The presence of residues did not significantly reduce the bond strength of resin composite to IPS Empress 2 ceramic.

Composite resin reinforced with pre-tensioned glass fibers. Influence of prestressing on flexural properties.

OBJECTIVES: This investigation evaluated the flexural properties of two composite resins, and the influence of unidirectional glass fiber reinforcements, with and without pre-tensioning. METHODS: Two composite resins (Q: Quixfil and A: Adoro) were used to fabricate 2 mm x 2 mm x 25 mm beams (N = 10), reinforced with two fiber bundles along the long axis of the beam and pre-tensioned under a load equivalent to 73.5% of its tensile strength (groups QPF and APF). In two other experimental groups, the bundles were similarly positioned but without pre-tension (groups QF and AF). Two more groups were included without fiber reinforcement (control groups Q and A). After 24h storage, specimens were subjected to a three-point flexural bending test to establish the flexural module, the deflection at initial failure and the flexural strength. Data were analyzed using a two-way analysis of variance (composite resin system and fiber reinforcement type) and the Tukey HSD post hoc tests (alpha = .05). RESULTS: The results showed that prestressing increased the flexural module of Adoro specimens (p<.001) but not Quixfil (p = .17). Prestressed beams reached greater deflection at initial failure than those conventionally reinforced (p<.001), namely .85-1.35 mm for Adoro and .66-.90 mm for Quixfil. Prestressing also significantly increased the flexural strength of beams (p<.001) in both Adoro and Quixfil groups, from 443.46 to 569.15 MPa and from 425.47 to 568.00 MPa, respectively. SIGNIFICANCE: Pre-tensioning of unidirectional glass fibers increased both deflection until initial failure and flexural strength of Quixfil and Adoro composite resins, however, with limited effects on the flexural modulus.