Aim The present in vitro study aimed to evaluate the bond strength of a bulk fill composite on dentin surfaces prepared with the Er: YAG laser. Methods Twenty-four permanent third molars were selected and divided into 2 groups: CP - Conventional preparation with high-speed handpiece (control) and LA (laser) - Preparation with Er: YAG laser. The occlusal surface was removed to expose coronal dentin, which was subsequently prepared with a high-speed handpiece or Er: YAG laser (350mJ, 4Hz, 1.5 ml/min water flow). Both groups were restored with Filtek One Bulk Fill (3M ESPE) composite resin. After 24 hours, the samples were evaluated for microtensile bond strength (µTBS), fracture pattern, and scanning electron microscopy (SEM). Results The data obtained in the µTBS test were submitted to t-test (α=0.05). The results showed no difference in µTBS when the different types of cavity preparation were compared (ρ=0.091). Fracture patterns revealed the prevalence of cohesive fracture in composite resin in CP (83.3%) and adhesive fracture in LA (92.1%). In the SEM analysis, the LA group demonstrated the presence of gaps between the composite resin and the irradiated dentin surface. The hybrid layer exhibited more regularity with the presence of longer and uniform resin tags in the CP group. Conclusion The type of cavity preparation did not influence the values of bulk fill composite resin µTBS to dentin. Fracture patterns and scanning electron microscopy analyses suggested less interference at the adhesive interface in preparations performed using CP.

Resumo O objetivo neste estudo foi avaliar o efeito da direção da corrente elétrica na resistência da união resina composta-dentina usando três sistemas adesivos. Dentes molares humanos foram distribuídos de acordo com o sistema adesivo (dois passos autocondicionante - Clearfil SE Bond, Kuraray [CSE]; e um passo autocondicionante - Single Bond Universal, 3M ESPE [SBU]; e dois passos convencional - Adper Single Bond 2, 3M ESPE [SB2]), a direção da corrente elétrica (sem corrente elétrica - controle, correntes elétricas direta e reversa - 35µA) e tempo de armazenamento (24h - imediato e 6 meses). Blocos de resina composta (Filtek Z350XT, 3M ESPE) foram aderidos à dentina. Amostras de dentina-resina foram produzidas e armazenadas em água destilada a 37ºC por 24 horas e 6 meses para o teste de resistência da união à microtração (µTBS) (n = 10; ~12 palitos por dente). Os padrões de fratura foram analisados em estereomicroscópio e classificados em falhas coesiva na dentina, coesiva na resina, adesiva ou mista. A penetração do adesivo na dentina e a formação da camada híbrida foram avaliadas em microscópio eletrônico de varredura (MEV). Os dados foram submetidos à ANOVA três fatores seguidos pelo teste post hoc de Tukey (α = 0,05). Não houve diferenças na µTBS quando os sistemas adesivos foram aplicados sob as correntes elétricas direta e reversa, mas ambas as correntes elétricas aumentaram a µTBS para todos os sistemas adesivos. SBU apresentou os menores valores de µTBS para o grupo controle em ambos os tempos de armazenamento e para a corrente elétrica direta em 6 meses de armazenamento. Falhas adesivas foram mais frequente em todos os grupos. A corrente elétrica formou longos tags resinosos para todos os sistemas adesivos. O armazenamento por 6 meses não diminuiu significativamente os valores de µTBS. Ambos os sentidos da corrente elétrica (cargas positivas e negativas) a 35µA podem aumentar a µTBS dos sistemas adesivos testados à dentina.

Abstract Thisstudy aimed to evaluate the effect of the electric current direction application on the resin composite-dentin bond strength using three adhesive systems. Human molar teeth were distributed according to the adhesive system (two-step self-etch - Clearfil SE Bond, Kuraray [CSE]; one-step self-etch - Single Bond Universal, 3M ESPE [SBU]; and two-step etch-and-rinse - Adper Single Bond 2, 3M ESPE [SB2]), electric current direction (without electric current - control, direct and reverse electric currents - 35µA), and storage time (24h - immediate and 6 months). Resin composite blocks (Filtek Z350XT, 3M ESPE) were bonded to dentin. The teeth/resin composites specimens were stored in distilled water at 37ºC for 24 hours and 6 months for the microtensile bond strength (µTBS) test (n = 10; ~12 sticks for each tooth). Failure patterns were analyzed on a stereomicroscope and classified as cohesive-dentin, cohesive-resin, adhesive or mixed. Adhesive penetration into dentin and hybrid layer formation were evaluated in a scanning electron microscope (n = 6). Data were submitted to a three-way ANOVA followed by Tukey’s post hoc test (α = 0.05). There are no differences in µTBS when the adhesive systems were applied under direct and reverse electric currents, but both electric currents increased the µTBS for all adhesive systems. SBU showed the lowest µTBS values for control groups in both storage times and direct electric current in 6 months of storage. The adhesive failure pattern was more frequently observed in all groups. The electric current formed long resin tags for all adhesive systems. Storage for 6 months did not significantly decrease µTBS values. Both directions of electric current (positive and negative charges) at 35µA can increase the µTBS of the adhesive systems tested to dentin.

Abstract: This paper evaluates the physicochemical and biological properties of experimental resin-based dual-cured calcium aluminate (CA) and calcium titanate (CTi) materials for vital pulp therapy (VPT). The experimental dual-cured materials were obtained as two pastes: a) Bis-EMA 10, PEG 400, DHEPT, EDAB, camphorquinone, and butylated hydroxytoluene; and b) fluoride ytterbium, Bis-EMA 10, Bis-EMA 30, benzoyl peroxide, and butylated hydroxytoluene. The materials were divided into six groups based on the added calcium component: MTA (MTA®, Angelus); CLQ (Clinker-Fillapex®, Angelus); CA (calcined at ,1200°C in pastes a and b); CA800 (calcined at 800°C in paste a); CA1200 (calcined at 1,200°C in paste a); and CTi (paste a). The real-time degree of conversion and rate of polymerization (n = 3), diametral tensile strength (n = 10), hydrogen potential (n = 15), calcium ion release (n = 10), water sorption and solubility (n = 10), and cell viability (n = 6) were evaluated. One- and two-way ANOVA and Tukey’s post hoc test were used in the analysis of the parametric data, and Kruskal-Wallis and Dunn’s multiple tests were used to analyze the nonparametric data (α = 0.05). CLQ, CA800 and CA1200 had the highest diametral tensile strength. The water solubility of MTA was similar to that of CA800, CA1200 and CTi. CA800 and CA1200 resulted in cell viabilities similar to those of MTA and CLQ. The experimental dual-cured CA-based material that calcined at 800°C showed physicochemical and biological properties suitable for VPT, and similar to those of MTA.

ABSTRACT: This study aimed to compare the trueness and precision of physical models manufactured chairside (intraoral scanner and 3D printed) or by plaster models obtained using impression with alginate or addition silicone. A full- arch stainless steel die was impressed to obtain ten physical models for each group. The models were measured in a stereomicroscope, considering four linear distances. To assess the precision accuracy, an analysis of the measurement variability was carried out, identified by the coefficients of variation and by the Levene’s test to compare the groups. To analyze trueness, the data average was subtracted from the database and compared considering alpha as 5 %. Considering precision, the higher dispersion of data occurred in the models obtained with silicone impression. And for trueness, Kruskal Wallis and Dunn tests results did not indicate differences between the groups in the anteroposterior linear distances (p> 0.05). Only in anterior transverse distance obtained through TRIOS (0.31 mm), it presented lower accuracy compared to the models from silicone impression (0.13 mm); however, at transverse posterior distance, the models from silicone impression showed the lowest accuracy (p <0.05). There was no difference between the models from scanning (p> 0.05). The physical dental models obtained by digital and analog workflows showed acceptable dimensional accuracy expressed by high precision and trueness. There is no difference between the evaluated intraoral scanner systems and the impression materials for the full-arch impression.

RESUMEN: Este estudio tuvo como objetivo comparar la veracidad y precisión de modelos físicos fabricados en la clínica dental (escáner intraoral e impreso en 3D) o por modelos de yeso obtenidos mediante impresión con alginato o silicona de adición. Una matriz de acero inoxidable de arco completo fue impresa para obtener diez modelos físicos para cada grupo. Los modelos se midieron en un estereomicroscopio, considerando cuatro distancias lineales. Se realizó un análisis de la variabilidad de la medida para evaluar la precisión, identificada por los coeficientes de variación y por la prueba de Levene para comparar los grupos. Para analizar la veracidad, el promedio de los datos se restó de la base de datos y se comparó considerando alfa como 5 %. Considerando la precisión, la mayor dispersión de datos ocurrió en los modelos obtenidos con impresión de silicona. Y para la veracidad, los resultados de las pruebas de Kruskal Wallis y Dunn no indicaron diferencias entre los grupos en las distancias lineales anteroposteriores (p> 0,05). Solo en la distancia transversal anterior obtenida mediante TRIOS (0,31 mm) presentó menor precisión en comparación con los modelos de impresión de silicona (0,13 mm); sin embargo, la distancia transversal posterior, los modelos de impresión de silicona mostraron la menor precisión (p <0,05). No hubo diferencia entre los modelos de escaneo (p> 0,05). Los modelos dentales físicos obtenidos mediante flujos de trabajo digitales y analógicos mostraron una precisión dimensional aceptable expresada por alta precisión y veracidad. No se observó diferencia entre los sistemas de escáner intraoral evaluados y los materiales de impresión para la impresión de arco completa.

ABSTRACT The aim of this study was to verify the effectiveness of alternative techniques for measuring the linear dimensional change of molds obtained by different impression materials. A stainless-steel die containing three lines was used to get the impressions. The impression materials were handled according to the manufacturers' instructions. After gelation/polymerization time, the molds (n=12) were stored for 30 minutes and the lines were subsequently measured using: a microscope (Olympus Measuring Microscope STM; Olympus Optical Co) with a 30x magnification (MM, control group), a digital caliper (Mitutoyo Digimatic; Kawasaki) (DC) and digitization using a digital camera (Canon EOS Rebel 3Ti; Canon) (DI). For each mold, a mean of the length of the lines was obtained. For each impression material, the difference in the length between the metallic matrix and the mold was considered as linear dimensional change (%). The data were submitted to the non-parametric Kolmogorov-Smirnov test, followed by one-way Analysis of Variance (ANOVA) for each material, and the means were compared by the Tukey test (α=0.05). The DI group promoted values of dimensional accuracy without significant differences with the control group (MM), except for the putty-body condensation silicone. The DC group showed significant differences for MM and DI groups for all impression materials tested. The DI group showed to be a reliable methodology (Standard error of the mean <10%) to measure the linear dimensional change of all impression materials. The DI group presented molds with linear dimensional change values without significant differences with MM group, except for the putty-body addition silicone. The digitization is a reliable methodology to evaluate the linear dimensional changes of molds made with impression materials, except for the putty-body elastomeric impression materials.

ABSTRACT This study evaluated the physico-mechanical properties of experimental composite resins made with different resin matrix and light-curing units. Experimental composite groups were divided according to monomers (BisGMA + TEGDMA-BT and BisGMA + BisEMA + UDMA + TEGDMA-BBUT) and photoinitiator system (camphorquinone-CQ and 1-phenyl-1,2-propanedione-PPD). A quartz tungsten halogen (QTH) or light-emitting diode (LED) were used to light cure all materials. Knoop microhardness (n = 10) was determined using Knoop microhardness test. Compressive strength, diametral tensile strength, and Young modulus (n = 7) were obtained using a universal testing machine at crosshead speed of 1.0 mm/min. The data were submitted to a three-way ANOVA and the Tukey post-hoc test (α = 0.05). QTH presented the highest total irradiance values and similar total radiant exposure to LED. For the compressive strength test, BT-PPD light-cured with LED group showed the lowest mean value. BT-CQ light-cured with LED group exhibited the lowest diametral tensile strength results. The BBUT-composite resins presented lowest Young modulus values, with no statistical difference between light-curing units (QTH and LED) and photoinitiators system (CQ and PPD). Application of QTH or LED in BT-based composite resins with PPD photoinitiator generated suitable results regarding the physico-mechanical properties.

ABSTRACT The aim of this study was to evaluate the depth of cure of conventional (Filtek Z350 and Esthet-X HD) and bulk fill resins composites (Filtek bulk fill flow and SDR) using different photoactivation methods. Samples were made using five disc-shaped matrices (1 mm high and 8 mm central diameter) with interposed polyester strips. The samples were photoactivated using different methods [continuous high-irradiance light (LCA), continuous low-irradiance light (LCB), and soft-start (SS)], maintaining 24 J/cm2 radiant exposure. After 24h, Knoop microhardness test was performed at 5 depths (surface, 1 mm, 2 mm, 3 mm and 4 mm). The Knoop microhardness were analyzed by ANOVA two-way and Tukey’s test (5%). Conventional resins presented the highest results up to 2 mm depth, except for Esthet-X photoactived by LCB, which showed significant lower Knoop hardness from 2 mm depth. Bulk fill resins photoactivated with LCA and SS had the highest results in 4 mm depth. The LCA and SS photoactivation methods produce suitable photoactivation in conventional composites up to 2 mm and bulk fill up to 4 mm depth and the bulk fill composites present higher polymerization depth than conventional composites.

Resumo O objetivo neste estudo foi avaliar o impacto de diferentes diâmetros de pinos de fibra de vidro (PFVs) na resistência de união à dentina. Quarenta dentes humanos unirradiculares foram tratados endodonticamente e utilizados para cimentação de PFVs (White Post DC, FGM) com diferentes diâmetros (n=10): P1 - ø 1,6 mm coronal x 0,85 mm apical; P2 - ø 1,8 mm coronal x 1,05 mm apical; P5 - ø 1,4 mm coronal x 0,65 mm apical; e PC - pino número 0,5 individualizado com resina composta (Tetric Ceram A2, Ivoclair Vivadent). Todos os PFVs foram cimentados no canal radicular usando cimento resinoso dual (Variolink II, Ivoclar Vivadent). As raízes foram seccionadas em três secções (cervical, média e apical) e submetidas ao teste push-out. Os modos de falha de todos os espécimes foram classificados em falha adesiva entre o cimento resinoso e pino, falha adesiva entre dentina e cimento resinoso, falha coesiva no cimento resinoso, pino ou dentina e falha mista. Os dados foram analisados com ANOVA two-way e teste de Tukey (a=0,05). Os maiores valores de resistência da união foram apresentados para os grupos P2 e PC. Não houve diferença estatisticamente significante entre os terços dos PFVs cimentados na raiz para cada grupo. Os grupos P2, P5 e PC apresentaram predominantemente falha adesiva entre a dentina e o cimento resinoso. Para o grupo P1, o tipo de falha mais prevalente foi a adesiva entre cimento resinoso e pino. Pode-se concluir que o pino de fibra de vidro bem adaptado ao canal radicular apresentou os maiores valores de resistência da união, independentemente do terço dos PFVs.

Abstract The aim of this study was to evaluate the effect of different glass fiber posts (GFPs) diameters on the push-out bond strength to dentin. Forty unirradicular human teeth were endodontically treated and used for cementation of GFPs (White Post DC, FGM) with different diameters (n=10): P1 - ø 1.6 mm coronal x 0.85 mm apical; P2 - ø 1.8 mm coronal x 1.05 mm apical; P5 - ø 1.4 mm coronal x 0.65 mm apical; and PC - customized post number 0.5 with composite resin (Tetric Ceram A2, Ivoclair Vivadent). All GFPs were cemented into the root canal using a dual-curing luting composite (Variolink II, Ivoclar Vivadent). One slice (1.7 mm) of each root third of cemented GFP (cervical, middle, and apical) was submitted to push-out testing. Failure modes of all specimens were classified as: adhesive failure between resin cement and post; adhesive failure between dentin and resin cement; cohesive failure within resin cement, post or dentin; and mixed failure. The data were analyzed with two-way ANOVA and Tukey’s test (a=0.05). The highest bond strength values were presented for the P2 and PC groups. There was no statistically significant difference between the GFP thirds in each group. The groups P2, P5, and PC showed predominantly adhesive failure. For P1, the most prevalent type of failure was adhesive between resin cement and post. It may be concluded that a glass fiber post that is well adapted to the root canal presents higher bond strength values, regardless of GFP third.

Resumo Esse estudo investigou a resistência de união de dois cimentos endodônticos experimentais à base de MTA e butiletilenoglicol dissalicilato: MTAe e MTAe. Os materiais de referência utilizados para comparação foram os cimentos endodônticos MTA Fillapex e AH Plus. Vinte incisivos superiores humanos foram selecionados e um slice dentinário de 1 mm de espessura foi obtido do terço cervical de cada raiz. Na superfície coronária de cada slice, quatro orifícios com 0,9 mm de diâmetro foram confeccionados através da dentina. Uma irrigação padronizada foi realizada e os orifícios foram preenchidos com um dos quatro cimentos endodônticos avaliados: AH Plus, MTA Fillapex, MTAe, e MTAe-HA. Os slices preenchidos foram armazenados em solução PBS (pH 7,2) durante 7 dias a 37°C. O ensaio de push-out foi realizado por meio de um dispositivo com 0,7 mm de diâmetro. A carga foi aplicada com a velocidade de 0,5 mm/min até a obtenção de deslocamento do material obturador. Os resultados foram expressos em MPa. O teste de Kruskal-Wallis foi aplicado para avaliar o efeito da resistência de união de cada cimento endodôntico. O teste de Mann-Whitney com correção de Bonferroni foi utilizado para isolamento das diferenças. O erro do tipo-alfa foi fixado em 0,05. Diferenças significantes entre os valores de medianas obtidos pelos materiais foram observados (p<0,001). O AH Plus demonstrou os maiores valores de resistência de união (p<0,001). Em contraste, o MTA Fillapex apresentou a menor resistência de união entre todos os cimentos testados (p<0,001). Os cimentos experimentais demonstraram valores intermediários, com ausência de diferenças estatísticas entre si (p>0,05). Em conclusão, os cimentos endodônticos experimentais à base de MTA e butiletilenoglicol dissalicilato apresentaram resultados adequados de resistência de união quando comparados ao MTA Fillapex.

Abstract This study investigated the bond strength of two experimental root canal sealers based on MTA and butyl ethylene glycol disalicylate: MTAe and MTAe-HA. The reference materials used for comparison were AH Plus and MTA Fillapex. Twenty human upper incisors were selected and one 1 mm slice was obtained from the cervical third of each root. On the coronal surface of each slice, four 0.9 mm wide holes were drilled through the dentine. Standardized irrigation was performed and holes were filled with one of the four tested sealers: AH Plus, MTA Fillapex, MTAe, and MTAe-HA. The filled slices were stored in a PBS solution (pH 7.2) for 7 days at 37 °C. A push-out assessment was performed with a 0.7 mm plunger tip. Load was applied at a crosshead speed of 0.5 mm/min until sealer displacement. The results were expressed in MPa. The Kruskal-Wallis test was applied to assess the effect of each sealer on the push-out bond strength. Mann-Whitney with Bonferroni correction was used to isolate the differences. The alpha-type error was set at 0.05. Significant differences among medians values obtained by materials were observed (p<0.001). AH Plus displayed the highest value of bond strength (p<0.001). In contrast, MTA Fillapex presented the lowest bond strength among all tested sealers (p<0.001). Experimental sealers showed intermediary bond strength values, with no statistical differences between them (p>0.05). In conclusion, experimental root canal sealers presented suitable bond strength outcomes when compared to MTA Fillapex.

Resumo O objetivo neste estudo foi sintetizar e avaliar as propriedades físico-químicas de um novo derivado do salicilato em cimentos endodônticos experimentais à base de cálcio. Dois derivados de salicilato foram sintetizados por meio de uma reação de trans esterificação do salicilato de metila com dois diferentes alcoóis (1,3-butilenoglicol dissalicilato-BD e pentaeritritol tetrassalicilato-PT) na proporção molar de 1: 3 e 1:6, respectivamente. Os produtos (BD e PT), foram caracterizados por espectroscopia infravermelho transformada de Fourier (FTIR) e espectroscopia de ressonância magnética nuclear (RMN). Os cimentos experimentais à base de cálcio foram preparados com a mesma pasta catalisadora (60% de MTA, 39% de N-etil o/p toluenosulfonamida e 1% de dióxido de titânio) e quatro concentrações diferentes de BD e PT nas pastas base (40/0 - controle, 35/5, 30/10 e 20/20) com 60% de óxido de bismuto. Os cimentos foram avaliados quanto ao tempo de endurecimento, à solubilidade (24 h, 7, 14 e 28 dias), resistência à tração diametral e ao módulo de elasticidade. Os dados foram analisados por ANOVA um ou dois fatores e as médias comparadas pelo teste de Tukey (p<0,05). A adição de PT reduziu o tempo de endurecimento dos materiais testados. Após 24 horas os cimentos 40/0 e 35/5 apresentaram maior solubilidade que os demais e após 14 e 28 dias o cimento 20/20 foi o que apresentou menor solubilidade (p<0,05). Após 7 dias o grupo 20/20 estabilizou a sua solubilidade. O cimento 40/0 apresentou os maiores valores e o cimento 20/20 apresentou os menores valores de resistência à tração diametral e módulo de elasticidade (p<0,05). A adição de PT a cimentos à base de cálcio possibilita benefícios ao tempo de presa e solubilidade.

Abstract The aim of this study was to synthesize and evaluate physicochemical properties of a new salicylate derivative in experimental calcium-based root canal sealers. Two salicylate derivatives were synthesized for the transesterification reaction of methyl salicylate with two different alcohols (1,3-butylenoglicol disalicylate-BD and pentaerythritol tetrasalicylate -PT) in molar ratio 1:3 and 1:6, respectively. The products (BD and PT), were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance spectroscopy (RMN). Calcium-based experimental sealers were prepared with the same catalyst paste (60% of MTA, 39% of n-ethyl-o-toluenesulfonamide, and 1% titanium dioxide) and four different concentrations of BD and PT in the base pastes (40/0 - control, 35/5, 30/10 and 20/20) with 60% of bismuth oxide. The experimental sealers were evaluated for setting time, solubility (24 h, 7, 14 and 30 days), diametral tensile strength and Young’s Modulus. Data were analyzed by one- or two-way ANOVA with Tukey’s test (p<0.05). The addition of PT reduced the materials setting time. After 24 h the sealer 40/0 and 35/5 had higher solubility, and after 14 and 28 days the sealer 20/20 showed the lowest solubility (p<0.05). After 7 days the sealer 20/20 stabilized its solubility. The sealer 40/0 presented the highest values and the 20/20 presented the lowest values of diametral tensile strength and Young’s modulus (p<0.05). The addition of PT to calcium-based root canal sealers provides benefits to the setting time and solubility.

ABSTRACT This study presents how the tooth whitening affects the bond strength and fracture type of three distinct adhesives — a conventional, a self-etching, and a universal adhesive — in enamel. Health bovine incisors were prepared by flattening the labial surface; part of these teeth was submitted to whitening treatment with a peroxide-based product (WhiteGold Office© 35%). The Single Bond©, AdheSE©, or Single Bond Universal© adhesive system were used to adhere a block of restorative resin to the flat surface of the teeth. Sticks measuring 10x1x1 mm were prepared and used in microtensile tests; they were also employed to examine the type of fracture. The results are analyzed with a two-way ANOVA. For both whitened and non-whitened specimens, the adhesive systems did not give statistically different bond strength values. However, the fracture shape (classified into four types) varied from a cohesive enamel type fracture for the whitened samples to a predominantly cohesive resin type fracture for the non-whitened teeth. Therefore, the whitening procedure has exerted a weakening effect on enamel even after 21 days post-treatment.

RESUMO Objetivo: Avaliar e comparar a precisão dimensional de três técnicas de moldagem: dupla mistura, reembasamento e moldeira individual. Métodos: Um modelo metálico inferior parcialmente edêntulo foi fabricado com pontos de referência nos dentes e usado para fazer as moldagens. As distâncias ântero-posteriores e transversais foram medidas. Todas as moldagens foram feitas com um silicone por adição utilizando moldeiras metálicas (técnicas da dupla mistura e reembasamento) ou de resina acrílica (técnica da moldeira individual). Na técnica da moldeira individual foi utilizado apenas o elastômero de viscosidade leve e nas técnicas da dupla mistura e reembasamento foram usados os elastômeros nas viscosidades denso e leve. Após os procedimentos de moldagem, a precisão dimensional de cada técnica de moldagem foi avaliada aferindo os modelos de gesso (n = 5) em um microscópio comparador com 30x de aumento e 0,5 µm de precisão. Os dados foram analisados estatisticamente por ANOVA dois fatores e teste de Tukey (p<0,05). Resultados: Os modelos de gesso feitos com todas as técnicas de moldagem apresentaram alterações lineares negativas (contração). As distâncias ântero-posteriores apresentaram maiores alterações dimensionais que as distâncias transversais. O lado parcialmente edêntulo teve maior contração que o lado ântero-posterior oposto. Conclusão: Não foram encontradas diferenças entre as técnicas de moldagem, mas foram observadas significantes alterações dimensionais.

ABSTRACT Objective: The purpose of this in vitro study was to assess and compare the dimensional accuracy of three impression techniques: 1-step putty/light-body, 2-step putty/light-body, and the monophase technique. Methods: A partially edentulous standard stainless steel mandibular arch cast with reference points on the teeth was used to make the impressions. The anteroposterior and transverse distances were measured. All impressions were made with a polyvinyl siloxane using stock metallic (1- and 2-step putty/light-body techniques) or acrylic resin (monophase technique) trays. The monophase impressions were made using a light-body material and the 1- and 2-step putty/light-body impressions with putty and light-body materials. After impression procedures, the accuracy of each technique was assessed measuring the stone casts (n = 5) poured from the impressions using a microscope at 30x magnification and at 0.5 µm accuracy. The data were analyzed statistically using 2-way ANOVA and Tukey's test (p<0.05). Results: Stone casts made by all techniques had significantly negative linear changes (shrinkage). The anteroposterior distances showed more dimensional changes than the transverse distances. The edentulous side showed more shrinkage than the anteroposterior side. Conclusion: No differences between the impression techniques were found, but significant dimensional changes were observed.

Resumo O objetivo deste estudo foi avaliar o efeito resistência de união de uma resina composta para pinos de fibra de vidro (PFV) tratados ou não com ácido fosfórico, agente de união (silano) e adesivo. PFVs foram condicionados ou não com ácido fosfórico 37% e receberam aplicação de diferentes materiais: um agente de união, um adesivo, ou ambos. Blocos em resina composta foram construídos a 4 mm de altura no PFV. O adesivo (20 s) e a resina composta (40 s) foram fotoativado por um diodo emissor de luz. As amostras foram armazenadas em água destilada a 37 C por 24 h. O teste de microtração foi realizado em uma máquina de ensaio universal (n=10). Os dados foram analisados usando ANOVA dois fatores e teste de Student-Newman-Keuls (p<0,05). Os padrões de fratura foram classificados em falhas adesivas, mistas ou coesivas. Amostras adicionais (n=3) foram feitas para análise da interface de união em microscopia eletrônica de varredura. A análise estatística mostrou que o fator 'recobrimento da superfície' foi significante (p<0,05), enquanto que o fator 'ácido fosfórico' (p=0,131) e a interação entre os fatores (p=0.171) não foram significantes. A maior resistência da união foi encontrada para os grupos silano e adesivo (p<0,05). Uma predominância de falhas adesivas e coesivas foi encontrada. Foram observadas diferenças em relação à homogeneidade e espessura da camada adesiva formada sobre os PFV com os diferentes tratamentos de superfície. Aplicação de silano e adesivo pode melhorar a resistência de união entre PFV e resina composta.

Abstract The aim of this study was to evaluate the bond strength of a composite resin to glass-fiber post (GFP) treated or not with phosphoric acid, silane coupling agent, and unfilled resin. GFPs were etched or not with 37% phosphoric acid and different surface coating applied: silane coupling agent, unfilled resin, or both. Composite resin blocks were built around a 4-mm height on the GFP. Unfilled resin (20 s) and composite resin (40 s) were light activated by a light-emitting diode unit. The specimens were stored in distilled water at 37 °C for 24 h. Microtensile bond test was performed using a mechanical testing machine until failure (n=10). The data were analyzed using two-way ANOVA followed by Student-Newman-Keuls' test (p<0.05). Failure modes were classified as adhesive, mixed, or cohesive failures. Additional specimens (n=3) were made to analyze the bonded interfaces by scanning electron microscopy. The statistical analysis showed the factor 'surface coating' was significant (p<0.05), whereas the factor 'HP etching' (p=0.131) and interaction between the factors (p=0.171) were not significant. The highest bond strength was found for the silane and unfilled resin group (p<0.05). A predominance of adhesive and cohesive failures was found. Differences regarding the homogeneity and thickness of the unfilled resin layer formed by different GFP surface treatments were observed. The application of silane and unfilled resin can improve the bond strength between GFP and resin composite.

O objetivo deste estudo foi mensurar e comparar a precisão dimensional de modelos de gesso de um arco mandibular parcialmente edêntulo feitos a partir de dois silicones por condensação, dois silicones por adição e três técnicas de moldagem (dupla mistura, reembasamento e moldeira individual). Um modelo metálico padrão de um arco mandibular parcialmente edêntulo foi obtido com pontos de referência nos caninos mandibulares permanentes esquerdo e direito, e segundo molares mandibulares permanentes esquerdo e direito. As distâncias anteroposteriores (entre o canino e segundo molar mandibulares esquerdos e entre o canino e segundo molar mandibulares direitos) e as distâncias transversais (entre os caninos mandibulares esquerdo e direito e entre os segundos molares mandibulares esquerdo e direito) do modelo metálico foram mensuradas através de um microscópio com 30x de aumento e 0,5 µm de precisão. Todas moldagens foram feitas com silicones por condensação e adição. As técnicas de dupla mistura e reembasamento foram realizadas com materiais nas viscosidades massa e leve e a técnica da moldeira individual somente com material leve. Após os procedimentos de moldagem, a precisão de cada material e técnica foi aferida medindo os modelos de gesso vazados (n=5) dos moldes, sob o mesmo microscópio. As diferenças entre os valores dos modelos de gesso e do modelo metálico foram calculadas, apresentadas como porcentagens e analisadas estatisticamente através da análise de variância e teste de Tukey (α=0,05). Todas as distâncias mensuradas nos modelos de gesso apresentaram dimensões alteradas com alterações lineares negativas (contração) significativas quando comparadas as medidas do modelo metálico. Os modelos de gesso feitos a partir de silicones por adição foram dimensionalmente mais precisos. Não foram encontradas diferenças entre as técnicas de moldagem.

The aim of this study was to measure and compare the dimensional accuracy of stone casts of a partially edentulous mandibular arch made by two condensation silicones, two addition silicones and three impression techniques (1-step putty/light-body, 2-step putty/light-body and monophase technique). A partially edentulous standard stainless steel mandibular arch cast was obtained with reference points on the permanent mandibular right and left canines, and permanent mandibular right and left second molars. The anteroposterior distances (between the mandibular left canine and second molar and between the mandibular right canine and second molar) and transverse distances (between the mandibular left and right canines and between the mandibular left and right second molars) of stainless steel cast were measured by a microscope at 30× magnification and 0.5 µm accuracy. All impressions were made with condensation or addition silicones. The 1- and 2-step putty/light-body impressions were accomplished with putty and light-body materials and the monophase impressions with light-body material only. After the impression procedures, accuracy of each material and technique was assessed measuring the stone casts poured (n=5) from the impressions, by the same microscope. The differences between the values of stone cast and stainless steel cast were calculated, presented as percentages and analyzed statistically by two-way ANOVA and the means compared by Tukey's test (α=0.05). All distances measured on stone casts showed altered dimensions with significantly negative linear changes (shrinkage) as compared to those of the stainless steel cast. The stone casts made from the addition silicones were dimensionally more accurate. No differences were found among the impression techniques.

The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced by using microwave drying. OBJECTIVE: This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail reproduction in type IV dental stones. MATERIAL AND METHODS: Three type IV dental stone brands were selected; elite Rock, Shera Premium and Durone IV. Two different drying protocols were tested in 4 groups (n=10); G1 - room temperature (25±4ºC) dried for 2 hours; G2 - room temperature dried for 24 hours; G3 - room temperature dried for 7 days and G4 - microwave oven dried at 800 W for 5 minutes and after 2 hours at room temperature. After drying, the samples were assayed for dimensional charges. The sample surface was submitted to the ImageTool 3.0 software for compressive strength in a universal testing machine with a cell load of 50 KN at a crosshead speed of 0.5 mm/minutes and the detail reproduction was analyzed with a stereomicroscope at 25x magnification. The statistical analysis of the linear dimensional change and compressive strength data were conducted by the ANOVA test followed by the Tukey test (p<0.05). Detailed reproduction values were reported in percentages. RESULTS: For the compressive strength test, Elite Rock and Durone IV did not present significant differences between G2 and G4, while Shera Premium did not present differences between G3 and G4. The best reproduction levels were observed for G3. CONCLUSIONS: Dental stone microwave oven drying showed a linear dimensional change similar to after room temperature drying for 24 hours and 7 days. The compressive strength of the stone dried in the microwave oven was similar to those dried at room temperature for 24 hours, with the exception of Shera Premium, which had similar results for microwave and room temperature drying for 7 days. For the microwave drying method the detail reproduction levels for samples dried at room temperature for 24 hours and 7 days were similar, except for the Durone IV.