O objetivo do presente estudo foi de avaliar os efeitos de diferentes frações de partículas de nanoargila modificadas do tipo montmorilonita Cloisite® 20A em propriedades físicas, mecânicas e biológicas de resinas experimentais do tipo nanohíbrida. Compósitos dentais foram preparados através da mistura de 30% de matriz resinosa (BisGMA/TEGDMA) em 70% de partículas de carga (vidro de bário silicato silanizado VB, dióxido de silício SD, partículas de nanoargila MMT). Quatro grupos de compósitos experimentais foram formados, variando o percentual de nanoargila empregada (0%, 5%, 7,5%, 10%). O processamento foi realizado em uma máquina de dupla mistura (SpeedMixer DAC, Germany, 3500 rpm). A citotoxicidade in vitro do material foi avaliada baseada nas normas ISO 10993- 5-2009 e comparado com compósito comercial. Ensaios mecânicos para cálculo de Resistência à Flexão e Módulo de Elasticidade foram realizados em máquina de ensaios universal EMIC. O aparelho Acuvol® foi utilizado para o ensaio de contração de polimerização. A sorção e solubilidade dos compósitos foram calculadas baseadas nas normas ISO 4049. Os dados foram analisados estatisticamente, utilizando-se a tabela ANOVA e o Teste de Tukey para comparação dos grupos de dois em dois. O nível de significância utilizado foi de 95% (p< 0,05). Por meio do exame dos resultados, concluiu-se que foi possível esfoliar 5 e 7,5% de partículas de MMT satisfatoriamente na matriz BisGMA/TEGDMA, porém, o inserção de 10% de MMT na matriz orgânica não trouxe vantagens ao compósito, certamente por não permitir a total exfoliação de suas partículas. A inserção de 5 e 7,5% de nanoargila ao compósito dental experimental possibilitou uma diminuição da contração de polimerização do material em 22,13 e 17,4%, respectivamente. Além disso, esses dois grupos permaneceram com suas propriedades mecânicas e de absorção e solubilidade satisfatórias, além de apresentar ausência de citotoxicidade para as células fibroblasticas L929 testadas

OBJECTIVE: The purpose of this in vitro study was to evaluate the internal adaptation of Class V composite restorations to the cavity walls using three different techniques of polymerization. METHODS: Standard cavities were prepared on the buccal and lingual surfaces of 24 extracted human third molars with margins located above and below the cementoenamel junction. Restorations were placed in one increment using two restorative systems: 3M Filtek A110/ Single Bond (M) and 3M Filtek Z250/ Single Bond (H) in the same tooth, randomly in the buccal and lingual surfaces. Resin composites were polymerized using three techniques: Group 1 - Conventional (60 s - 600 mW/cm²); Group 2 - Soft-start (20 s - 200 mW/cm² , 40 s - 600 mW/cm²); Group 3 - Pulse Activation (3 s - 200 mW/cm², 3-min hiatus, 57 s - 600 mW/cm²). Buccolingual sections were polished, impressions taken and replicated. Specimens were assessed under scanning electron microscopy up to X1000 magnification. Scores were given for presence or absence of gaps (0 - no gap; 1 - gap in one wall; 2 - gap in two walls; 3 - gap in three walls). RESULTS: The mean scores of the groups were (±SD) were: G1M-3.0 (± 0.0); G2M-2.43 (± 0.8); G3M- 1.71 (± 0.9); G1H- 2.14 (± 1.2); G2H- 2.00 (± 0.8); G3H- 1.67 (± 1.1). Data were analyzed using Kruskal-Wallis and Dunnet's tests. No statistically significant difference (p>;0.05) was found among groups. Gaps were observed in all groups. CONCLUSIONS: The photocuring technique and the type of resin composite had no influence on the internal adaptation of the material to the cavity walls. A positive effect was observed when the slow polymerization techniques were used.

OBJECTIVE: The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Material and METHODS: Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm) were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm² / 20 s and gradual - 100 up to 1000 mW/cm² / 10 s + 1000 mW/cm² / 10 s. After storage in distilled water (37&deg;C/7 days), the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (alpha=0.05). RESULTS: ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. CONCLUSIONS: The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction.

The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (;a; or = 0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87&plusmn;0.01) and Definite (1.89&plusmn;0.01) shrank significantly less than the other composite resins. SureFil (2.01&plusmn;0.06), Filtek Z250 (1.99&plusmn;0.03), and Fill Magic (2.02&plusmn;0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

The aim of this study was to evaluate the polymerization shrinkage and shrinkage stress of composites polymerized with a LED and a quartz tungsten halogen (QTH) light sources. The LED was used in a conventional mode (CM) and the QTH was used in both conventional and pulse-delay modes (PD). The composite resins used were Z100, A110, SureFil and Bisfil 2B (chemical-cured). Composite deformation upon polymerization was measured by the strain gauge method. The shrinkage stress was measured by photoelastic analysis. The polymerization shrinkage data were analyzed statistically using two-way ANOVA and Tukey test (p

IntroduçãoAtualmente, devido ao aumento das exigências e padrões estéticos mais elevados, as resinas compostas tornaram-se o material de eleição para a restauração de dentes posteriores. Apesar das resinas Bulk-fill representarem uma alternativa tentadora devido à menor complexidade e maior rapidez na sua utilização, alguns médicos dentistas encontram-se reticentes quanto à utilização deste material.ObjetivoO objetivo deste estudo é comparar o desempenho clínico das resinas Bulk-fill e resinas convencionais em restaurações diretas de dentes posteriores, avaliando algumas características direta ou indiretamente, nomeadamente a “descoloração, módulo de elasticidade, resistência à fratura, fadiga, resistência à oclusão e medições de desgaste de abrasão e atrito”, que foram consideradas pela Academy of Dental Materials como as características mais relevantes.Materiais e métodosAs bases de dados que foram utilizadas para realizar a pesquisa foram: PubMed/MEDLINE, Excerpta Medica Database (Embase), Cochrane Library e Web of Science. Esta revisão umbrella da literatura cumpre as normas PRISMA e avalia a qualidade dos estudos através da ferramenta AMSTAR 2.ResultadosA pesquisa das diferentes bases de dados que foi elaborada até março 2022 resultou num total de 40 artigos. Os estudos incluídos caracterizam-se por serem revisões sistemáticas que visam comparar as diferentes características mecânicas de resinas convencionais e resinas Bulk-fill em restaurações de dentes posteriores. Com a aplicação dos critérios da ferramenta AMSTAR 2, as revisões foram consideradas de baixa a moderada. A meta-análise no global, ainda que sem significado estatístico, favorece maioritariamente o uso da resina convencional, sendo cerca de 5 vezes mais provável obter um resultado favorável com resina convencional do que com a resina Bulk-fill.ConclusõesAs resinas Bulk-fill resultam numa simplificação do processo clínico de restaurações diretas posteriores. O desempenho clínico em termos de propriedades mecânicas de resinas Bulk-fill e resinas convencionais demonstrou que estas apresentam um comportamento similar, com tendência de melhor desempenho das resinas convencionais.Key-WordsAbrasão, Bulk-fill, contração de polimerização, microinfiltração, módulo de elasticidade, resina composta.

Introduction: The composite SonicFillTM (Kerr/Kavo) recently introduced in the market is indicated for posterior restorations, with a single increment up to 5mm due to reduced polymerization shrinkage, thus reducing working time. Aim: Evaluation of marginal microleakage with SonicFillTM. Method and materials: In this in vitro experimental study, were sectioned thirty noncarious human molars in occluso-cervical direction. Class V cavities were prepared on the buccal or lingual surfaces of each tooth with gingival margin walls in enamel and dimensions: 4 mm mesiodistally, 3 mm occlusogingivally and 3 mm depth. The specimens were divided in 4 groups: group 1 - restored with SonicFillTM (Kerr/Kavo), group 2 - restored with FiltekTM Supreme XTE (3M ESPE), group 3 – the cavities were not restored; group 4 – restored with SonicFillTM (Kerr/Kavo). In groups 1, 2 and 4 the enamel is conditioned with 37% orthophosphoric acid and applied the self-etch adhesive system ClearfilTM SE BOND (Kuraray). The specimens were stored in distilled water at 37ºC for 7 days. Followed thermocycling: 500 cycles between 5ºC and 55ºC with a dwell time of 30 seconds. After immersed for 3 hours in a solution of 99mTc-Pertechnetate the radioactivity was assessed with a gamma camera. The nonparametric Kruskal-Wallis and Mann-Whitney test with Bonferroni correction at a significance level of 5% were used for the statistical analyses. Results: There are significative differences between the positive and negative control groups and between these and experimental groups (p <0.05). There are no statistically significant differences between the specimens restored with SonicFillTM and FiltekTM Supreme XTE. Conclusion: The new composite SonicFillTM and FiltekTM Supreme XTE didn’t show difference concern to the dye penetration. The SonicFillTM restorative system doesn’t show influence in what concerns to microleakage.

Introduction: OptiBond XTRTM recently introduced in the market is a new mild self-etch adhesive bonding agent which is claimed to feature an enhanced etching ability of the primer in order to the decrease of the pH. Aim: Evaluate the microleakage of dental restorations using OptibondTM XTR. The null hypothesis was that the type adhesive system doesn’t have influence in what concerns to microleakage. Materials and methods: Thirty noncarious extracted human molars were selected and cut in two equal halves occlusogingivally. Class V cavities (4mm/3mm/3mm) were prepared on the buccal or lingual surfaces of each tooth with gingival margin walls in enamel. The specimens were randomly divided into 4 groups: 1- OptibondTM XTR was applied; 2 –ClearfillTM SE BOND was applied; 3 – the cavities weren’t restored; 4 – OptibondTM XTR was applied. In groups 1, 2 and 4 the enamel was conditioned (37% orthophosphoric acid) before the adhesive application and restored with SonicFillTM. The specimens were stored in distilled water (37ºC, 7 days) and then went through thermocycling (500 cycles, 5ºC and 55ºC, dwell time 30’’). Two coats of nail polish were applied to the external surface around of each restoration except to the negative control group, where the crowns were completely sealed. The specimens were submersed in a solution of 99mTc-Pertechnetate. The radioactivity was counted 3 hours later. The nonparametric Kruskal-Wallis test, with Bonferroni correction at a significance level of 5%, was used for statistical analyses. Results: Results showed that there weren’t statistically significant differences (p>0.05) among the groups restored with ClearfillTM SE and OptibondTM XTR. Conclusion: Based on the results of this study, the OptibondTM XTR doesn’t reduce microleakage compared to ClearfillTM SE BOND.

Introduction: due to their excellent aesthetic properties and to the improvement of some mechanical properties, the composites have been acquiring increasing importance in the context of oral rehabilitation. There are, however, some disadvantages that may compromise their clinical success, such as polymerization shrinkage, which could be associated to contraction stress transferred to the tooth, leading to cusp deflection and/or enamel microcracks. On the other hand, stress at the tooth-composite interface has the potential to cause adhesive failure, leading to post-operative sensitivity, microleakage, recurrent caries, and ultimately, to pulp inflammation. Objectives: The aim of this work was to make a pilot study regarding the capability of optical fiber Bragg grating (FBG) sensors to evaluate the linear polymerization shrinkage of composite resins. Materials and methods: Two different composite resins (SDRTM and Esthet X HD – Dentsply DeTrey, Konstanz, Germany) were placed in plastic molds crossed by a fiber Bragg grating sensor and light-cured by a LED unit (Bluephase®, Ivoclar Vivadent, Lichtenstein). Strain in μƐ was plotted as a function of time (seconds), obtaining a representative curve. Besides linear shrinkage evaluation, additional measurements were made concerning the temperature rise induced on the FBG sensor solely due to the LED light curing irradiation and for thermal characterization of both composite resins during light-curing process. Results: it was observed an initial expansion either due to thermal absorption of light curing unit either from the exothermic reaction of composite polymerization immediately followed by linear contraction, which reached 0,43% to Esthet X HD and 0,42% to SDRTM. Conclusions: The optical fiber Bragg grating sensors can be used to evaluate linear polymerization shrinkage of dental composites with clear advantages to assess the evolution of composite shrinkage in real time during all polymerization process. Introdução: devido às suas excelentes propriedades estéticas e à melhoria das suas propriedades mecânicas, as resinas compostas têm vindo a conquistar um papel progressivamente crescente no âmbito da reabilitação oral. Contudo, de entre algumas das suas desvantagens inerentes, a contração de polimerização assume um papel crucial pelas consequências que pode originar como a deflexão cuspídea, propagação de microfracturas e ruptura da interface adesiva da restauração, potenciando a presença de fendas marginais e consequente microinfiltração, sensibilidade pós-operatória, recidiva de cárie e, em última instância, de patologia pulpar. Objectivos: realizar um estudo piloto sobre a capacidade de avaliação da contração de polimerização linear de resinas compostas com recurso a redes de Bragg gravadas em fibra óptica (FBG). Materiais e métodos: introduziu-se uma rede de Bragg num molde de plástico, que posteriormente se preencheu com duas resinas compostas (SDRTM e Esthet X HD – Dentsply DeTrey, Konstanz, Germany) colocadas ao redor da fibra, procedendo-se à sua fotopolimerização com um fotopolimerizador de LEDs (Bluephase®, Ivoclar Vivadent, Lichtenstein). A força da contração, medida em μƐ, foi traçada em função do tempo (em segundos), obtendo uma curva representativa da contração linear. Para além da contração, foram registadas as variações de temperatura provocadas somente pela irradiação do fotopolimerizador de LEDs e durante a polimerização das resinas compostas. Resultados: foi possível observar uma ligeira expansão inicial das resinas compostas imediatamente seguida por contração linear que atingiu valores de 0,43% para o Esthet X HD e 0,42% para o SDRTM. Conclusões: O uso de FBG para avaliação da contração de polimerização linear das resinas compostas é um método viável com vantagens claras na monitorização em tempo real de todo o processo de polimerização.

OBJECTIVE: The purpose of this in vitro study was to evaluate the internal adaptation of Class V composite restorations to the cavity walls using three different techniques of polymerization. METHODS: Standard cavities were prepared on the buccal and lingual surfaces of 24 extracted human third molars with margins located above and below the cementoenamel junction. Restorations were placed in one increment using two restorative systems: 3M Filtek A110/ Single Bond (M) and 3M Filtek Z250/ Single Bond (H) in the same tooth, randomly in the buccal and lingual surfaces. Resin composites were polymerized using three techniques: Group 1 - Conventional (60 s - 600 mW/cm²); Group 2 - Soft-start (20 s - 200 mW/cm² , 40 s - 600 mW/cm²); Group 3 - Pulse Activation (3 s - 200 mW/cm², 3-min hiatus, 57 s - 600 mW/cm²). Buccolingual sections were polished, impressions taken and replicated. Specimens were assessed under scanning electron microscopy up to X1000 magnification. Scores were given for presence or absence of gaps (0 - no gap; 1 - gap in one wall; 2 - gap in two walls; 3 - gap in three walls). RESULTS: The mean scores of the groups were (±SD) were: G1M-3.0 (± 0.0); G2M-2.43 (± 0.8); G3M- 1.71 (± 0.9); G1H- 2.14 (± 1.2); G2H- 2.00 (± 0.8); G3H- 1.67 (± 1.1). Data were analyzed using Kruskal-Wallis and Dunnet's tests. No statistically significant difference (p>0.05) was found among groups. Gaps were observed in all groups. CONCLUSIONS: The photocuring technique and the type of resin composite had no influence on the internal adaptation of the material to the cavity walls. A positive effect was observed when the slow polymerization techniques were used.