Can composition and preheating improve infiltrant characteristics and penetrability in demineralized enamel?

Abstract The composition of infiltrants can influence their physical properties, viscosity and depth of penetration (DP). Strategies are used to increase the DP, such as the addition of diluents or the use of heat. This study aimed to evaluate the effect of preheating and composition on physical properties and DP of infiltrants in demineralized enamel. The groups were assigned, and the following experimental formulations were made: 25%BisEMA +75%TEGDMA; 25%BisEMA +65%TEGDMA +10%ethanol; 25%BisEMA +65%TEGDMA +10%HEMA; 100%TEGDMA; 90%TEGDMA +10%ethanol; 90%TEGDMA +10%HEMA. The samples were photoactivated at two temperatures (25°C and 55°C). Degree of conversion (DC) was performed using an infrared spectrophotometer. Elastic modulus (E), flexural strength (FS) and contact angle (CA) tests were also performed. The DP of an infiltrant in demineralized enamel was determined by confocal laser scanning microscopy (CLSM) using an indirect labeling technique. The data were analyzed by two-way ANOVA and Tukey's test. DC increased after preheating in all the groups; however, 90%TEGDMA+10%ethanol showed the lowest DC for both temperatures, and the lowest E. Preheating did not influence E or FS. The CA increased at 55°C for most groups, but decreased for groups containing HEMA. Temperature did not seem to influence DP, and Icon showed the lowest DP values. The 100%TEGDMA composition showed more homogeneous penetration, whereas Icon showed heterogeneous and superficial penetration. The preheating technique does not improve all properties in all the material compositions. The composition of a material can influence and improve its properties.

Avaliação dos efeitos do Bisfenol A em queratinócitos e células de neoplasia de cavidade oral / Evaluation of bisphenol A effects in keratinocytes and oral cavity neoplasia cells

O Bisfenol A (BPA) é um monômero utilizado na produção de garrafas plásticas, embalagens alimentícias, resinas odontológicas e vários outros materiais. Este monômero age como um desregulador do sistema endócrino e seus efeitos estão associados a cânceres em diferentes órgão e tecidos, como mama, próstata e tireóide. O BPA já foi detectado em fluidos humanos, incluindo saliva, mas os seus efeitos na mucosa bucal e em células orais neoplásicas não foram investigados. Os objetivos do presente trabalho foram 1) verificar os efeitos da exposição crônica ao BPA em glândulas salivares e mucosa bucal in vivo e 2) avaliar os efeitos do BPA in vitro em células de neoplasias bucais e queratinócitos; Para atender ao objetivo 1, camundongos machos e fêmeas receberam BPA (200 mg/mL) na água de beber durante 6 semanas. As mucosas orais (palato, língua e mucosa jugal) e as glândulas submandibulares foram avaliadas. Para atender ao objetivo 2, a resposta ao BPA foi examinada nas linhagens NOK-SI (queratinócito), HN12, HN13 (CCE de cavidade oral), UM HMC1 e UM HMC3a (neoplasia de glândula salivar). Os seguintes parâmetros foram avaliados: viabilidade, proliferação, invasão, angiogênese, produção de citocinas e fatores de crescimento e possíveis mecanismos de ação do BPA. Resultados. A exposição de camundongos ao BPA resultou em alterações microscópicas caracterizadas pelo aumento da espessura do epitélio da mucosa oral (palato, língua e mucosa jugal) e uma redução no número de ácinos das glândulas submandibulares. Foi observado também um acúmulo de BPA nos tecidos orais. In vitro, nas linhagens de CCE, o BPA aumentou a proliferação, invasão celular e os níveis da proteína vimentina, e ainda induziu a secreção de citocinas e fatores de crescimento, e a acetilação de histonas H3. Em queratinócitos orais, o BPA aumentou a proliferação celular e induziu a secreção de fatores de crescimento e a expressão de receptores de estrógeno (ER) α e ß. Os efeitos do BPA foram revertidos na presença do antagonista puro do ER. Nas linhagens de neoplasias de glândula o BPA não alterou a proliferação e induziu a expressão de p63. Em conclusão, o BPA induz alterações morfológicas nos tecidos bucais e alterações moleculares nos queratinócitos e nas células de CCE de cavidade oral. Os mecanismos pelos quais o BPA induz estas alterações são dependentes da interação BPA-ER e da acetilação de histonas.

Bisphenol A (BPA) is a monomer used to product plastic bottles, food packaging, inner coating of food cans, thermal papers, medical devices, dental resins and various other materials. Due to its chemical structure, this monomer acts as a deregulator of the endocrine system and its effects are associated with cancers in different organs and tissues such as breast, endometrium, ovary, prostate, testis and thyroid. BPA has been detected in several human fluids, including saliva, however its effects on the normal oral mucosa and neoplastic oral cells have not been investigated yet. Thus, the objectives of the present study were 1) to verify the effects of chronic exposure to BPA in salivary glands and oral mucosa in vivo and 2) to evaluate the effects of BPA in vitro on oral tumor cells and keratinocytes. To meet objective 1, male and female mice received BPA (200 mg / mL) in drinking water for 6 weeks. The oral mucosa (palate, tongue and buccal mucosa) and submandibular salivary glands were evaluated microscopically. To meet objective 2, the response to BPA was examined in immortalized cell lines NOK SI (keratinocyte); HN12, HN13 (OSCC), UM HMC1 and UM HMC3a (salivary gland tumor). The following parameters were evaluated: viability, proliferation, invasion, angiogenesis, cytokine and growth factors production. Results. Exposure of mice to BPA resulted in microscopic changes characterized by increased thickness of the oral mucosa epithelium (palate, tongue and buccal mucosa) and a reduction in the number of submandibular salivary glands acini. There was also an accumulation of BPA in the oral tissues. In vitro, in OSCC cells, BPA increased cell proliferation and invasion, vimentin expression, induced secretion of cytokines and growth factors, and induced histone H3 acetylation. In oral keratinocytes, BPA increased cell proliferation and induced secretion of growth factors and estrogen receptor (ER) α and ß expression. The effects of BPA were reversed in the presence of the pure ER antagonist. In salivary gland tumor cell lines, BPA did not alter the proliferation and induced the expression of p63. BPA mechanism of action involves its interaction with ER, since the effects were reverted in the presence of pure receptor antagonist. In conclusion, BPA induces morphological changes in oral tissues and molecular changes in keratinocytes and OSCC cells. The mechanisms which BPA induces these changes are dependent to the BPA-ER interaction and histone acetylation.

Efeitos da colagem do esporão lingual no microambiente periodontal e liberação de subprodutos de materiais resinosos no tratamento de mordida aberta anterior em crianças / Effects of lingual sporing collage on the periodontal micro-environment and release of by-products of resin materials on the treatment of anterior open bite in children

Introdução: O aparelho ortodôntico passivo esporão é um método utilizado em crianças para correção de mordida aberta anterior. Para realizar a fixação desses acessórios dentes é necessário a utilização de materiais resinosos que podem liberar subprodutos tóxicos como BisGMA e TEGDMA. Além disso, a movimentação dentária ortodôntica pode aumentar a concentração de interleucinas no fluido crevicular gengival (FCG). A liberação de subprodutos resinosos no tratamento de mordida aberta e o comportamento da expressão de interleucinas ainda não estão elucidados na literatura. Objetivo: (1) avaliar a expressão de citocinas no FCG em crianças com mordida aberta que receberam fixação de esporão como tratamento e (2) quantificar o BisGMA e TEGDMA na saliva desses pacientes; e (3) avaliar a migração e viabilidade de quetarinócitos humanos expostos à resina. Métodos: Foram selecionados pacientes da clínica da FO-UFMG que apresentaram mordida aberta anterior. A colagem dos esporões foi realizada e os excessos de resina foram removidos. Foram realizados exames clínico e periodontal nos incisivos superiores e inferiores, coletas do FCG (antes da colagem ­ baseline, 24 h e 7 d após) e saliva (baseline, 30 min, 24 h e 7 d após a colagem). As citocinas do FCG foram analisadas por meio do BD™ Cytometric Bead Array e as amostras de saliva, através do método de cromatografia líquida de alta eficiência. Para as análises in vitro, células imortalizadas HaCat foram tratadas com meio de cultura condicionados com incrementos do sistema resinoso em 3 diferentes diluições e posteriormente foram realizados os testes de viabilidade e migração celular. Resultados: O estudo in vivo demonstrou que houve aumento do sangramento gengival nos incisivos inferiores após 7d quando comparados ao baseline e que este índice estava maior nos dentes inferiores do que nos superiores. Em 24h e 7d após a fixação do esporão, os níveis de IL-8 nos incisivos superiores estavam aumentados. Em 7d, a concentração de IL-1ß foi aumentada em comparação ao baseline nos dois grupos de dentes. Comparando os incisivos superiores e inferiores, os níveis de IL-8, IL-1ß e IL-6 foram maiores nos superiores às 24h. A produção de citocinas pôde ser positivamente correlacionada com o aumento do volume do FCG. Houve aumento dos níveis de BisGMA e TEGDMA na saliva em 30min, com redução dos níveis em 24h e 7d. Os resultados in vitro demonstraram aumento da migração celular nos queratinóscitos expostos aos meios condicionados mesmo em baixas concentrações .Conclusão: Foi identificado que após a colagem do esporão lingual ocorreu o aumento na expressão de interleucinas no FCG. Além disso, foi possível identificar a liberação de subprodutos resinosos na saliva das crianças. Embora os mesmos possam interferir na migração celular, não há estudos que quantifiquem a exposição mínima capaz de induzir alterações no indivíduo. Sendo assim, os benefícios da colagem do esporão sobrepõem seus efeitos adversos

Introduction: The passive spur orthodontic appliance is a method used in children to correct anterior open bite. To fix these teeth accessories, it is necessary to use resinous materials that can release toxic by-products such as BisGMA and TEGDMA. In addition, orthodontic tooth movement can increase the concentration of interleukins in the gingival crevicular fluid (FCG). The release of resinous by-products in the treatment of open bite and the behavior of interleukin expression are not yet elucidated in the literature. Objective: (1) to evaluate the expression of cytokines in the FCG in children with open bite who received spur fixation as treatment and (2) to quantify the BisGMA and TEGDMA in the saliva of these patients; and (3) evaluate the migration and viability of human ketarinocytes exposed to the resin. Methods: Patients from the FO-UFMG clinic who presented anterior open bite were selected. The spurs were bonded and the excess resin was removed. Clinical and periodontal examinations were performed on the upper and lower incisors, collections of the FCG (before bonding - baseline, 24 h and 7 d after) and saliva (baseline, 30 min, 24 h and 7 d after bonding). The FCG cytokines were analyzed using the BD ™ Cytometric Bead Array and the saliva samples, using the high performance liquid chromatography method. For in vitro analysis, immortalized HaCat cells were treated with culture medium conditioned with increments of the resin system in 3 different dilutions and then the viability and cell migration tests were performed. Results: The in vivo study showed that there was an increase in gingival bleeding in the lower incisors after 7d when compared to the baseline and that this index was higher in the lower than in the upper teeth. At 24h and 7d after spur fixation, IL-8 levels in the upper incisors were increased. At 7d, the concentration of IL-1ß was increased compared to the baseline in the two groups of teeth. Comparing the upper and lower incisors, the levels of IL-8, IL-1ß and IL-6 were higher in those above 24h. Cytokine production could be positively correlated with increased FCG volume. There was an increase in the levels of BisGMA and TEGDMA in saliva in 30 minutes, with a reduction in levels in 24h and 7d. The in vitro results demonstrated an increase in cell migration in keratinocytes exposed to conditioned media even in low concentrations. Conclusion: It was identified that after the gluing of the tongue spur there was an increase in the expression of interleukins in the FCG. In addition, it was possible to identify the release of resinous by-products in children's saliva. Although they can interfere with cell migration, there are no studies that quantify the minimum exposure capable of inducing changes in the individual. Therefore, the benefits of spur bonding override its adverse effects.

Avaliação da solubilidade e sorção em água de alguns materiais restauradores diretos / Evaluation of solubility and sorption in water of some direct restorative materials

Resumo Introdução A solubilidade e sorção dos materiais restauradores são considerados fatores críticos, pois podem interferir na qualidade e durabilidade das restaurações. Objetivo Avaliar a solubilidade e sorção de água de alguns materiais restauradores. Material e método Foram confeccionados quatorze espécimes de cada um dos seguintes materiais: Equia® Forte, Z100, Fuji IX/ e Vidrion R, os quais foram levados a uma dessecadora e pesados diariamente até estabilização. Em seguida, foram inseridos em recipientes individuais contendo 40 mL de água destilada cada e divididos em dois grupos de acordo com o tempo de armazenagem: 7 ou 30 dias. Ao final de cada período, os espécimes foram retirados da água, pesados, levados à dessecadora e pesados novamente até estabilização. Os resultados foram analisados estatisticamente utilizando os testes ANOVA 2 critérios e Tukey. Resultado Com exceção do Equia® Forte e Z100, os demais materiais, apresentaram uma variação significativa da solubilidade ao longo do tempo. Quanto à sorção, observa-se que apenas o material Z100 não apresentou diferença significativa em relação ao tempo de armazenagem, mas, na comparação entre os materiais, todos apresentaram diferenças significativas em ambos os períodos. Conclusão Após os períodos de armazenagem de 7 e 30 dias em água, os materiais restauradores Equia® Forte e Z100 não apresentam variação significativa da solubilidade, sendo mais estáveis que os materiais Fuji IX e Vidrion R. Os materiais à base de ionômero de vidro, Equia® Forte, Fuji IX e Vidrion R, sofrem mais sorção em água quando comparados ao material Z100 em ambos os períodos.

Abstract Introduction The solubility and sorption parameters of restorative materials are considered critical factors since they may interfere with the quality and durability of restorations. Objective The aim of this study was to evaluate the solubility and water sorption of some restorative materials. Material and method Fourteen specimens were made (10.0 mm x 2.0 mm) of each of the following material: Equia® Forte, Z100, Fuji IX/ e Vidrion R, then taken to a desiccator and weighed daily until stabilized. They were then placed in individual containers with 40mL of distilled water each and divided into two groups according to the storage time: 7 or 30 days. At the end of each period, the specimens were removed from the water, weighed, taken to the desiccator and weighed again until stabilized. The results were analyzed statistically with two-way ANOVA and Tukey. Result Except for Equia® Forte and Z100, the other materials presented a significant variation of solubility over time. As for sorption, it was noticed that only Z100 presented no significant difference in relation to the storage time, but in comparison of the materials, all had significant differences in both 7 and 30 days periods. Conclusion After storage periods of 7 and 30 days in water, the restorative materials Equia® Forte and Z100 do not present significant variation of solubility, being more stable than the materials Fuji IX and Vidrion R. The glass ionomer-based materials, Equia® Forte, Fuji IX and Vidrion R, suffer more sorption in water when compared to Z100 material in both periods.

Twenty-four-month clinical performance of different universal adhesives in etch-and-rinse, selective etching and self-etch application modes in NCCL - a randomized controlled clinical trial

Abstract Objective The aim of this randomized, controlled, prospective clinical trial was to evaluate the performances of two different universal adhesives and one etch-rinse adhesive for restoration of non-carious cervical lesions (NCCLs). Material and Methods Twenty patients with at least seven NCCLs were enrolled. Lesions were divided into seven groups according to adhesive systems and application modes: GSE: GLUMA Universal-self-etch, GSL: GLUMA Universal-selective etching, GER: GLUMA Universal-etch-and-rinse, ASE: All-Bond Universal-self-etch, ASL: All-Bond Universal-selective etching, AER: All-Bond Universal-etch-and-rinse, SBE (Control): Single Bond2-etch-and-rinse. A total of 155 NCCLs were restored with a nano hybrid composite (Tetric N-Ceram). Restorations were scored with regard to retention, marginal discoloration, marginal adaptation, recurrent caries and post-operative sensitivity using modified United States Public Health Service (USPHS) criteria after one week, 6, 12 and 24 months. Statistical evaluations were performed using Chi-square tests (p=0.05). Results The recall rate was 81.9% after the 24-month follow-up. The cumulative retention rates for self-etch groups (GSE: 72.2%, ASE:75%) were significantly lower than other experimental groups (GSL: 93.7%, GER: 100%, ASL: 94.1%, AER: 100%, SBE: 100%) at the 24-month follow-up (p<0.05). Regarding marginal adaptation and marginal discoloration, GSE and ASE groups demonstrated more bravo scores after 6 and 12-month observations but differences were not significant (p>0.05). Only one restoration from ASL group demonstrated post-operative sensitivity at 6 and 12-month observations. No secondary caries was observed on the restorations at any recall. At the end of 24-month observations, no significant differences were detected among groups regarding any of the criteria assessed, except retention. Conclusion GLUMA Universal and All-Bond Universal showed better results in etch-and-rinse and selective etching mode compared to the self-etch mode regarding retention. Etch-and-rinse and selective etching application modes of the current universal adhesives tended to provide better clinical outcomes considering the criteria evaluated at the end of 24-month evaluation.

Composite-derived monomers affect cell viability and cytokine expression in human leukocytes stimulated with Porphyromonas gingivalis

Abstract Objectives: Dental composites release unreacted resin monomers into the oral environment, even after polymerization. Periodontal cells are, therefore, exposed to substances that potentially elicit the immune inflammatory response. The underlying molecular mechanisms associated with the interaction between resin monomers and human immune cells found in the gingival crevicular fluid are not fully understood yet. This study investigated the ability of bisphenol A-glycidyl methacrylate (BISGMA), urethane dimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA) to induce apoptosis and cytokine release by human leukocytes stimulated with a periodontal pathogen. Methodology: Peripheral blood mononuclear cells (PBMC) from 16 healthy individuals were included in this study. To determine the toxicity, the PBMC were incubated for 20 hours, with monomers, for the analysis of cell viability using MTT assay. To evaluate cell death in the populations of monocytes and lymphocytes, they were exposed to sub-lethal doses of each monomer and of heat-inactivated Porphyromonas gingivalis (P. gingivalis) for 5 hours. Secretions of IL-1β, IL-6, IL-10 and TNF-α were determined by ELISA after 20 hours. Results: UDMA and TEGDMA induced apoptosis after a short-time exposure. Bacterial challenge induced significant production of IL-1β and TNF-α (p<0.05). TEGDMA reduced the bacterial-induced release of IL-1β and TNF-α, whereas UDMA reduced IL-1β release (p<0.05). These monomers did not affect IL-10 and IL-6 secretion. BISGMA did not significantly interfere in cytokine release. Conclusions: These results show that resin monomers are toxic to PBMC in a dose-dependent manner, and may influence the local immune inflammatory response and tissue damage mechanisms via regulation of bacterial-induced IL-1β and TNF-α secretion by PBMC.

Mechanical-physicochemical properties and biocompatibility of catechin-incorporated adhesive resins

Abstract Several anti-proteolytic dentin therapies are being exhaustively studied in an attempt to reduce dentin bond degradation and improve clinical performance and longevity of adhesive restorations. Objectives This study assessed the effect of epigallocatechin-3-gallate (EGCG) on long-term bond strength when incorporated into adhesives. Material and Methods Adhesive systems were formulated with EGCG concentrations of 0 wt%: (no EGCG; control); 0.5 wt% EGCG; 1.0 wt% EGCG, and 1.5 wt% EGCG. Flexural strength (FS), modulus of elasticity (ME), modulus of resilience (MR), compressive strength (CS), degree of conversion (DC), polymerization shrinkage (PS), percentage of water sorption (%WS), percentage of water solubility (%WL) and cytotoxicity properties were tested. Dentin microtensile bond strength (µTBS) was evaluated after 24 h and again after 6 months of water storage. The adhesive interface was analyzed using scanning electron microscopy (SEM). Results No significant differences were found among the groups in terms of FS, ME, MR, CS and PS. EGCG-doped adhesives increased the DC relative to the control group. EGCG concentrations of 1.0 wt% and 0.5 wt% decreased the WS of adhesives. WL decreased in all cases in which EGCG was added to adhesives, regardless of the concentration. EGCG concentrations of 1.0 wt% and 0.5 wt% reduced cytotoxicity. EGCG concentrations of 1.0 wt% and 0.5 wt% preserved µTBS after 6 months of storage, while 1.5 wt% EGCG significantly decreased µTBS. SEM: the integrity of the hybrid layer was maintained in the 0.5 wt% and 1.0 wt% EGCG groups. Conclusion EGCG concentrations of 1.0 wt% and 0.5 wt% showed better biological and mechanical performance, preserved bond strength and adhesive interface, and reduced cytotoxicity.

A randomized, prospective clinical study evaluating effectiveness of a bulk-fill composite resin, a conventional composite resin and a reinforced glass ionomer in Class II cavities: one-year results

Abstract Bulk-fill restorative materials such as bulk-fill composite resins and high viscous glass ionomer cements have become very popular materials in operative dentistry because their application is easy and time-saving. Objectives: The aim of this clinical study was to evaluate the clinical performance of a highly viscous reinforced glass ionomer material, a bulk-fill composite resin and a micro hybrid composite resin in Class II restorations. Methodology: In total, 109 Class II restorations were performed in 54 patients using three different restorative materials: Charisma Smart Composite (CSC); Filtek Bulk Fill Posterior Restorative (FBF); Equia Forte Fil (EF). Single Bond Universal adhesive (3M ESPE, Germany) was used with composite resin restorations. The restorations were evaluated using modified USPHS criteria in terms of retention, color match, marginal discoloration, anatomic form, contact point, marginal adaptation, secondary caries, postoperative sensitivity and surface texture. The data were analyzed using Chi-Square, Fischer's and McNemar's tests. Results: At the end of one year, 103 restorations were followed up. No changes were observed during the first 6 months. At the end of one year, there were small changes in composite restorations (FBF and CSC) but no statistically significant difference was observed between the clinical performances of these materials for all criteria (p>0.05). However, there was a statistically significant difference between EF, FBF and CSC groups in all parameters except marginal discoloration, secondary caries and postoperative sensitivity in one-year evaluation (p<0.05). Conclusion: Bulk-fill composite resins and conventional composite resins showed more successful clinical performance than highly viscous reinforced glass ionomers in Class II cavities.

Caracterização in vitro de uma resina composta bulk fill contendo partículas pré-reagidas de ionômero de vidro (S-PRG) / In vitro characterization of a bulk-fill resin composite containing pre-reacted glass ionomer fillers (S-PRG)

No ambiente bucal, as restaurações de resina composta estão sujeitas a ações físicas, provenientes do desgaste e carga oclusal, e químicas, pelo contato com a saliva e os alimentos. Os efeitos desses processos físico-químicos estão diretamente relacionados com a característica da composição do material restaurador resinoso. Ensaios laboratoriais são especialmente importantes para avaliar a resistência física e estabilidade química dos materiais restauradores. O objetivo do estudo foi realizar a caracterização in vitro de uma resina composta bulk fill contendo partículas pré-reagidas de ionômero de vidro (S-PRG) (Beautifil-Bulk, Shofu Inc). As variáveis dependentes foram resistência à flexão (FS), absorção de água (WS) e solubilidade (SL), grau de conversão (DC), liberação de monômeros em água destilada e morfologia superficial em microscopia eletrônica de varredura (MEV), após incubação da resina composta em água destilada. As variáveis independentes foram a cor da resina composta, em cinco níveis, e o tempo de armazenamento dos corpos-de-prova, em seis níveis. Os ensaios de FS, WS e SL foram realizados de acordo com a metodologia preconizada pela ISO 4049(2009). Os corpos-de-prova para os ensaios de liberação de monômeros e análise de superfície em MEV foram confeccionados com as dimensões de 15 mm de diâmetro por 1 mm de espessura , usando resina da cor A3. O grau de conversão foi determinado em corpos-de-prova cilíndricos (1 x 1 mm) com resina da cor A3. Para confecção de todos os corpos-de-prova foi utilizado o fotopolimerizador LED RadiiCal (SDI Inc., Victoria, Austrália; 1200 mW/cm2). Após os períodos de incubação das amostras em água destilada (10 min, 24 h, 7 dias, 30 dias, 3 e 6 meses), foram realizadas análises em cromatografia líquida de alta eficiência (HPLC) para identificação e quantificação de monômeros liberados, usando padrões de Bis-GMA e TEGDMA. Para análise de superfície, os corpos-de-prova incubados em água destilada (7 dias, 30 dias, 3 e 6 meses) receberam pulverização de 4 nm de carbono e foram avaliados em MEV (FEI - Quanta 200, FEG). Os resultados foram expressos em média e desvio padrão. Foram realizados testes de normalidade (Kolmogorov-Smirnov e Shapiro-Wilk) e de homocedasticidade (Levene). Análise de Variância (ANOVA) e teste de comparações múltiplas, e teste de Kruskal-Wallis verificaram as diferenças entre os níveis dos fatores em estudo. Foi adotado o nível de significância de 5%. Não houve diferença significativa entre as cores para as variáveis FS, WS e SL (p>0,05). A média (dp) do DC foi 59,37(14,49)%. TEGDMA foi identificado em todos os tempos avaliados com maiores concentrações aos 30 dias e 3 meses de armazenamento. Bis-GMA não foi detectado em nenhuma das soluções. As imagens em MEV mostraram alterações morfológicas sugestivas de rugosidade da superfície aos 6 meses de armazenamento. A resina composta Giomer Beautifil-Bulk atingiu os requisitos da norma ISO 4049(2009) para FS, WS e SL e apresentou um DC aceitável. Não houve liberação de Bis-GMA e o TEGDMA foi detectado durante todo o período de 6 meses de avaliação.

In the oral environment, composite resin restorations are subject to physical actions, from occlusal wear and tear, and chemical actions, through contact with saliva and food. The effects of these physicochemical processes are directly related to the composition characteristic of resin restorative material. Laboratory assays are especially important for assessing the physical strength and chemical stability of restorative materials. The objective of the study was to perform in vitro characterization of a bulk fill composite containing glass ionomer pre-reacted particles (S-PRG) (Beautifil-Bulk, Shofu Inc). The dependent variables were flexural strength (FS), water sorption (WS) and solubility (SL), degree of conversion (DC), elution of monomers in distilled water and surface morphology in scanning electron microscopy (SEM). The independent variables were the shades of the composite resin, in five levels, and the storage time of the specimens, in six levels. The FS, WS and SL assays were performed according to the methodology recommended by ISO 4049:2009. For monomer elution assay and surface analysis in SEM specimens were made with 15 mm diameter and 1 mm thickness, using A3 shade resin. The degree of conversion was determined in cylindrical specimens measuring 1 x 1 mm with A3 shade resin. For the preparation of all the specimens, the Radii-Cal LED light curing unit (SDI Inc., Victoria, Australia, 1200 mW / cm2) was used. After the incubation periods of the samples in distilled water (10 min, 24 h, 7 days, 30 days, 3 and 6 months), analyzes were performed in high performance liquid chromatography (HPLC) for the identification and quantification of elution monomers using Bis-GMA and TEGDMA standards. For surface analysis, specimens incubated in distilled water (7 days, 30 days, 3 and 6 months) were sprayed with 4 nm of carbon and were evaluated in SEM (FEI-Quanta 200, FEG). The results were expressed as mean and standard deviation. Normality tests (Kolmogorov-Smirnov and Shapiro-Wilk) and homoscedasticity test (Levene) were performed. Analysis of Variance (ANOVA) and multiple comparison test, and Kruskal-Wallis test verified the differences between the levels of the factors under study. The significance level of 5% was set. There was no significant difference among the resin shades for FS, WS and SL (p> 0.05). The mean (SD) of DC was 59.37 (14.49)%. TEGDMA was identified at all time points with the highest concentrations at 30 days and 3 months of storage. Bis-GMA was not detected in any of the solutions. SEM images showed morphological changes suggestive of surface roughness at 6 months of storage. The composite resin Giomer Beautifil-Bulk reached the requirements of ISO 4049:2009 for FS, WS and SL and presented acceptable DC. There was no release of Bis-GMA and TEGDMA was detected throughout the 6-month evaluation period.

Evaluation of physical-mechanical properties, antibacterial effect, and cytotoxicity of temporary restorative materials

Abstract The objective of this study was to compare selective physical-mechanical properties, antibacterial effects and cytotoxicity of seven temporary restorative materials (TRM): five resin-based materials [Bioplic (B), Fill Magic Tempo (FM), Fermit inlay (F), Luxatemp LC (L) and Revotek LC (R)], and zinc oxide-eugenol cement (IRM) and glass ionomer cement (GIC) as the controls. Material and methods The physical-mechanical properties were evaluated by determining microleakage (ML), ultimate tensile strength (UTS) and Shore D hardness (SDH). In addition, the polymerization rate (Pr-1), depth of cure (DC), water sorption and solubility (WS/SL) were evaluated. The antimicrobial effects of the materials were assessed by biofilm accumulation of Streptococcus mutans (BT) and the direct contact test (DCT) by exposure to Enterococcus faecalis for 1 and 24 h, and cytotoxicity by MTT assay. The data were analyzed by ANOVA or Kruskall-Wallis tests, and a complementary post-hoc method (p<0.05). Results Group B, followed by FM and GIC had significantly lower percentages of microleakage in comparison with the other groups; Groups FM and L showed the highest WS, while Groups R and FM showed the significantly lowest SL values (p<0.05). Group R showed the statistically highest UTS mean and the lowest DC mean among all groups. Group F showed the lowest S. mutans biofilm accumulation (p=0.023). Only the Group L showed continued effect against E. faecalis after 1 h and 24 h in DCT. The L showed statistically lower viability cell when compared to the other groups. Conclusions These findings suggest the antibacterial effect of the temporary materials Fill Magic and Bioplic against S. mutans, while Luxatemp showed in vitro inhibition of S. mutans biofilm accumulation and E. faecalis growth. Regarding the cell viability test, Luxatemp was the most cytotoxic and Fill Magic was shown to be the least cytotoxic.

Structural and mechanical properties of a giomer-based bulk fill restorative in different curing conditions

ABSTRACT Objective: The main goal of this study was to compare the polymerization degree of bulk-fill giomer resin cured with three different light-curing units (LCUs): a polywave third-generation (Valo); a monowave (DemiUltra: DU); and a second-generation LED (Optima 10: Opt) LCUs by using structural and mechanical properties. Material and methods: Giomer samples of 2 and 4 mm cured with three LCUs were employed in vitro analysis. The degree of curing (DC%) was determined with Fourier-Transform Infrared Spectroscopy (FTIR). Microstructural features were observed with scanning electron microscopy (SEM). Flexural strength (FS), compression strength (CS), elastic modulus and fracturing strain were determined for mechanical properties. Surface microhardness (SMH) values were also measured. Oneway ANOVA, two-way analysis of variance and Tukey multiple comparison tests were used for statistically analyzing the FS and SMH. Results: DC% values were 58.2, 47.6, and 39.7 for the 2 mm samples cured with DU, Opt., and Valo LCUs, respectively. DC% values of the 4 mm samples were 50.4, 44.6, and 38.2 for DU, Opt, and Valo, respectively. SMH values were Valo, Opt<DU at top of the samples; Valo<DU, Opt at 2 mm, and DU, Valo<Opt at 4 mm depth. Giomer samples cured with Opt and DU exhibited higher FS values than Valo. CS values were similar but compressive modulus and fracturing strain (%) varied depending on the curing protocol. Conclusions: Based on the results, it can be concluded that curing device and protocol strongly affect crosslinking reactions and thus DC%, SMH, compressive modulus and strain at break values. Consequently, it can be deduced that curing protocol is possibly the most important parameter for microstructure formation of highly-filled composite restoratives because it may bring some structural defects and physical frailties on restorations due to lower degree of polymerization.

Model resin composites incorporating ZnO-NP: activity against S. mutans and physicochemical properties characterization

Abstract Although resin composites are widely used in the clinical practice, the development of recurrent caries at composite-tooth interface still remains as one of the principal shortcomings to be overcome in this field. Objectives To evaluate the activity against S. mutans biofilm of model resin composites incorporating different concentrations of ZnO-nanoparticles (ZnO-NP) and characterize their physicochemical properties. Materials and Methods Different concentrations of ZnO-NP (wt.%): E1=0, E2=0.5, E3=1, E4=2, E5=5 and E6=10 were incorporated into a model resin composite consisting of Bis-GMA-TEGDMA and barium borosilicate particles. The activity against S. mutans biofilm was evaluated by metabolic activity and lactic acid production. The following physicochemical properties were characterized: degree of conversion (DC%), flexural strength (FS), elastic modulus (EM), hardness (KHN), water sorption (Wsp), water solubility (Wsl) and translucency (TP). Results E3, E4, E5 and E6 decreased the biofilm metabolic activity and E5 and E6 decreased the lactic acid production (p<0.05). E6 presented the lowest DC% (p<0.05). No significant difference in FS and EM was found for all resin composites (p>0.05). E5 and E6 presented the lowest values of KHN (p<0.05). E6 presented a higher Wsp than E1 (p<0.05) and the highest Wsl (p<0.05). The translucency significantly decreased as the ZnO- NP concentration increased (p<0.05). Conclusions The incorporation of 2 - 5 wt.% of ZnO-NP could endow antibacterial activity to resin composites, without jeopardizing their physicochemical properties.

Effect of erosive challenges on deciduous teeth undergoing restorative procedures with different adhesive protocols - an in vitro study

ABSTRACT Objective: To evaluate the effect of erosive challenges on the tooth- restoration interface of deciduous teeth treated with different adhesive protocols. Material and Methods: Deciduous molars were cut mesiodistally, then embedded, abraded and polished (n=80). Samples were randomly divided according to the adhesive system used into: G1 (Adper Single Bond2®, etch-and-rinse), G2 (Universal Single Bond®, self-etching), G3 (OptibondFL®, etch-and-rinse with Fluoride) and G4 (BondForce®, self-etching with Fluoride). After standardized cavity preparation (2 mm diameter x 2 mm depth), adhesive systems were applied and samples were restored (composite resin Z350®). Half of the samples were exposed to erosive/abrasive cycles (n = 10, each adhesive group), and the other half (control group; n = 10) remained immersed in artificial saliva. For microleakage analysis, samples were submersed in methylene blue and analyzed at 40x magnifications. Cross-sectional microhardness (CSMH) was carried out (50 g/5 s) at 25 μm, 50 μm, and 100 μm from the eroded surface and at 25 μm, 75 μm, and 125 μm from the enamel bond interface. Results: Regarding microleakage, 7.5% of the samples showed no dye infiltration, 30% showed dye infiltration only at the enamel interface, and 62.5% showed dye infiltration through the dentin-enamel junction, with no difference between groups (p≥0.05). No significant difference was observed in CSMH at different depths (two-way ANOVA, p≥0.05). Conclusions: We did not observe significant changes in microleakage or CSMH after erosive/abrasive challenges in deciduous teeth treated with different adhesive protocols (etch-and-rinse and self-etching adhesives, with and without fluoride).

Rubbing time and bonding performance of one-step adhesives to primary enamel and dentin

Abstract Objectives: This study investigated whether increasing the concentration of acidic monomers in one-step adhesives would allow reducing their application time without interfering with the bonding ability to primary enamel and dentin. Material and methods: Experimental one-step self-etch adhesives were formulated with 5 wt% (AD5), 20 wt% (AD20), or 35 wt% (AD35) acidic monomer. The adhesives were applied using rubbing motion for 5, 10, or 20 s. Bond strengths to primary enamel and dentin were tested under shear stress. A commercial etch-and-rinse adhesive (Single Bond 2; 3M ESPE) served as reference. Scanning electron microscopy was used to observe the morphology of bonded interfaces. Data were analysed at p<0.05. Results: In enamel, AD35 had higher bond strength when rubbed for at least 10 s, while application for 5 s generated lower bond strength. In dentin, increased acidic monomer improved bonding only for 20 s rubbing time. The etch-and-rinse adhesive yielded higher bond strength to enamel and similar bonding to dentin as compared with the self-etch adhesives. The adhesive layer was thicker and more irregular for the etch-and-rinse material, with no appreciable differences among the self-etch systems. Conclusion: Overall, increasing the acidic monomer concentration only led to an increase in bond strength to enamel when the rubbing time was at least 10 s. In dentin, despite the increase in bond strength with longer rubbing times, the results favoured the experimental adhesives compared to the conventional adhesive. Reduced rubbing time of self-etch adhesives should be avoided in the clinical setup.

Mechanical properties, water sorption characteristics, and compound release of grape seed extract-incorporated resins

Abstract Objective This study evaluated the effect of grape seed extract (GSE) incorporation on the mechanical properties, water sorption, solubility, and GSE release from the experimental adhesive resins. Material and Methods An experimental comonomer mixture, consisting of 40% Bis-GMA, 30% Bis MP, 28% HEMA, 0.26% camphorquinone and 1% EDMAB, was used to prepare four GSE-incorporated adhesive resins at concentrations of 0.5, 1, 1.5, and 2 wt%. The neat resin without GSE was used as the control. Six resin beams (25 mm x 2 mm x 2 mm) per group were prepared for flexural strength and modulus of elasticity evaluations using a universal testing machine at a crosshead speed of 1 mm/min. Five disks (6 mm in diameter and 2 mm in thickness) per group were used for microhardness measurements using a Leitz micro-hardness tester with Leica Qgo software. Five disks (7 mm in diameter and 2 mm in thickness) per group were prepared and stored in deionized water for 28 days. Water sorption, solubility, and GSE release in deionized water were calculated for each GSE-incorporated adhesive at the end of 28th day. Data was evaluated using one-way ANOVA and Tukey multiple comparisons. Results Flexural strength, modulus of elasticity and microhardness of GSE-incorporated adhesive decreased significantly with incorporation of 1.5% of GSE (p<0.05). Addition of GSE had no effect on the water sorption of the adhesive resins (p=0.33). The solubility of the resin also increased significantly with incorporation of 1.5% of GSE (p<0.05). Quantities of GSE release increased with increased concentration of GSE in the adhesive resin. Conclusion Up to 1% of GSE can be incorporated into a dental adhesive resin without interfering with the mechanical properties or solubility of the resins.

Degree of conversion and bond strength of resin-cements to feldspathic ceramic using different curing modes

Abstract Resin cements have led to great advances in dental ceramic restoration techniques because of their ability to bond to both dental structures and restorative materials. Objective The aim of this study was to assess the performance of resin cements when different curing modes are used, by evaluating the degree of conversion and bond strength to a ceramic substrate. Material and Methods Three resin cements were evaluated, two dual-cured (Variolink II and RelyX ARC) and one light-cured (Variolink Veneer). The dual-cured resin cements were tested by using the dual activation mode (base and catalyst) and light-activation mode (base paste only). For degree of conversion (DC) (n=5), a 1.0 mm thick feldspathic ceramic disc was placed over the resin cement specimens and the set was light activated with a QTH unit. After 24 h storage, the DC was measured with Fourier transform infrared spectroscopy (FTIR). For microshear bond strength testing, five feldspathic ceramic discs were submitted to surface treatment, and three cylindrical resin cement specimens were bonded to each ceramic surface according to the experimental groups. After 24 h, microshear bond testing was performed at 0.5 mm/min crosshead speed until the failure. Data were submitted to one-way ANOVA followed by Tukey test (p<0.05). Scanning electron microscopy (SEM) was used for classifying the failure modes. Results Higher DC and bond strength values were shown by the resin cements cured by using the dual activation mode. The Variolink II group presented higher DC and bond strength values when using light-activation only when compared with the Variolink Veneer group. Conclusion The base paste of dual-cured resin cements in light-activation mode can be used for bonding translucent ceramic restorations of up to or less than 1.0 mm thick.

Influência da adição de nanotubos de TiO2 na biocompatibilidade de cerâmicas Y-TZP e de materiais a base de resina / Influence of the addition of TiO2 nanotubes on the biocompatibility of Y-TZP ceramics and resin-based materials

O objetivo deste estudo in vitro foi avaliar a biocompatibilidade de uma zircônia tetragonal policristalina estabilizada por ítrio (Y-TZP), um cimento à base de resina (RelyX ™ Ultimate) e um adesivo à base de 10-MDP (Single Bond Universal) modificados ou não por nanotubos de titânio (TiO2), por meio dos testes de viabilidade celular MTT e Cristal Violeta. Para este fim, foram obtidos discos de 13 mm x 2 mm de zircônia Y-TZP (IPS e.max ZirCAD). Os discos de cimento resinoso e adesivo com 10-MDP foram obtidos através de um molde metálico com as mesmas dimensões. Para Y-TZP, a incorporação de nanotubos de TiO2 ocorreu antes da sinterização, enquanto para os materiais à base de resina, 0,3% em peso de nanotubos foram adicionados antes da fotopolimerização. Os espécimes foram divididos em 8 grupos (n = 8). A avaliação in vitro foi feita através de testes nos quais as células da linhagem de fibroblastos NIH 3T3 foram colocadas em contato indireto com estes materiais. Para a viabilidade celular foram realizados MTT e Cristal Violeta em duplicata e após 24, 48 e 72 horas a absorbância foi analisada por espectrofotometria em leitora Elisa. Os dados obtidos foram submetidos a ANOVA a dois critérios, seguido do teste de Tukey (α = 0,05). Os resultados mostraram que em 24 e 48 hs todos os materiais mostraram-se biocompatíveis. No período de 72 hs os maiores aumentos de absorbância aconteceram para os grupos Y-TZP sem nanotubos de TiO2 e adesivo com nanotubos de TiO2 comparados aos demais grupos. De modo geral, a incorporação de nanotubos a estes materiais não interferiu na viabilidade celular em ambos os testes.(AU)

The aim of this in vitro study was to evaluate the biocompatibility of yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP), a resin-based cement (RelyX™ Ultimate) and a 10- MDP-based adhesive (Single Bond Universal) modified or not by titanium nanotubes (TiO2), by means of the MTT cell viability test and Crystal Violet. For this purpose, disks of 13 mm in diameter per 2 mm is thickness of pre-sintered Y-TZP zirconia (IPS e.max ZirCAD) were obtained. The resin-cement and a 10-MDP adhesive disks were obtained through a metal mold with the same dimensions. For Y-TZP, the incorporation of TiO2 nanotubes occured before sinterization, while for the resin-based materials 0.3wt% of nanotubes were added to the uncured materials. The specimens were divided into 8 groups (n = 8). The in vitro evaluation was carried out by means of tests in which fibroblast line NIH 3T3 cells were placed into indirect contact with these materials. For cell viability were made MTT assay tests and Crystal Violet in duplicate and after 24, 48 and 72 hours the absorbance levels were analyzed by spectrophotometry Elisa reader. The data obtained were submitted to two-way ANOVA, followed by Tukey test (α = 0.05). In the period of 72 the highest increases of absorbance happened for the groups Y-TZP without TiO2 nanotubes and adhesive with TiO2 nanotubes when compared to the other groups. In general, the incorporation of nanotubes into these materials did not interfere with cell viability in both tests.(AU)

Efeito da contaminação por saliva humana na interface adesiva: resistência de união, análise de camada híbrida e conversão de sistemas adesivos / Effect of human saliva contamination on adhesive interface: bond strength, hybrid layer analysis and conversion of adhesive systems

Este estudo teve como objetivo analisar o efeito da contaminação por saliva humana na resistência de união (RU) da interface adesiva em dentina por microtração, nas características morfológicas da camada híbrida (CH) em microscopia confocal e no grau de conversão (GC) de 2 sistemas adesivos: Adper Single bond 2 (SB) e Single Bond® Universal (SU). Cento e oitenta dentes terceiros humanos hígidos foram divididos em 12 grupos (n=10), de acordo com o sistema adesivo utilizado, a presença de saliva e o tempo de armazenagem. Após o procedimento adesivo e aplicação da resina composta Filtek Z250, os dentes foram mantidos em água destilada em estufa a 37°C por 48 horas, 6 meses ou 12 meses antes de serem seccionados em palitos (0,8mm x 0,8mm, aproximadamente) para serem levados à máquina de ensaios universal Instron para os testes de microtração. Para à análise da interface adesiva em microscopia confocal de varredura a laser para verificação e mensuração de alterações internas na interface foram utilizados 60 dentes divididos em 6 grupos (n=10) de acordo com os tempos de 48 horas, 6 meses, e 12 meses respectivamente, empregando os sistemas adesivos (SB) e (SU). O efeito da presença de saliva também foi avaliado pelo grau de conversão dos adesivos, empregando-se espectroscopia de infravermelho transformada de Fourier empregando os sistema adesivos (SB) e (SU) com incorporação de saliva humana na sua composição (n=5) com concentrações 10%, 25% e 50% em vol. Para a comparação das variáveis: RU, (GC), espessura da CH, na presença de saliva e tempo de armazenamento foram utilizados os testes de Análise de Variância a três critérios e de comparações múltiplas de Tukey (p<0,05). Os valores de RU (MPa±dp: 48horas/6meses/1ano) foram: SB (43,53 ±6,0; 40,10±3,4; 38,59±5,4); SalSB (43,09±6,2; 39,86±6,6; 37,255,8); SU (42,98±4,3; 39,30±3,6; 40,44±5,7); Sal SU (44,39±4,2; 42,26±2,5; 38,26±5,7). Os Valores médios da CH (MPa±dp: 48horas/6meses/1ano) foram: SalSB (3,59±0,8; 3,59±1,0; 2,08±1,5). SalSU (1,26±0,5; 1,73±0,8; 1,07±0,3). Os valores de GC (MPa±dp: 10%/25%/50%vol) foram: SB (85,59±3,4; 49,68±12,8; 38,56±11,8); SU (85,52±3,3; 86,27±3,5; 57,82±11,1).Conclui-se, portanto, que a contaminação por saliva humana não interferiu na RU da interface dentina/resina composta após 48 horas, 6 meses e 12 meses. A morfologia da camada hibrida foi alterada pela presença da saliva nos períodos 6 e 12 meses,. O GC dos sistemas adesivos foi afetado pela presença de saliva após a polimerização imediata. Entretanto o fator tempo foi determinante para a deformação da interface dentina/resina para ambos os sistemas adesivos.(AU)

The objective of this study was to analyze the effect of human saliva contamination on bond strength of the dentin/adhesive interface, morphology of the hybrid layer by confocal microscopy and SEM analysis and degree of conversion of 2 adhesive systems: Adper Single bond 2 (SB) and Single Bond® Universal ( SU). One hundred and eighty healthy human third teeth were divided into 12 groups (n = 10), according to the adhesive system used, the presence of saliva and the storage time. After the adhesive procedure and placement of resin composite (Filtek Z250), the teeth were stored in distilled waterat 37 ° C for 48 hours, 6 months or 12 months before being cut into sticks (0.8mm x 0.8mm, approximately) to the microtensile strength tests. For the analysis of the adhesive interface in confocal microscopy of laser scanning for verification and measurement of internal interface changes, 60 teeth were used divided into 6 groups (n = 10) according to the storage time: 48 hours, 6 months, and 12 monthsand (SB) and (SU). The effect of the presence of saliva was also evaluated by the degree of conversion of the adhesives using Fourier transform infrared spectroscopy employing adhesive (SB) and (SU) systems incorporating human saliva in its composition (n = 5) with 10%, 25% and 50% vol. For the comparison of the variables: bond strength, degree of conversion, and hybrid layer thickness in the presence of saliva and storage time, the three criteria Variance Analysis and Tukey multiple comparisons tests (p <0.05) were used. The values of bond strength (MPa ± dp: 48hours / 6meses / year) were: SB (43.53 ± 6.0, 40.10 ± 3.4, 38.59 ± 5.4); SalSB (43.09 ± 6.2, 39.86 ± 6.6, 37.255.8); SU (42.98 ± 4.3, 39.30 ± 3.6, 40.44 ± 5.7); SU salt (44.39 ± 4.2, 42.26 ± 2.5, 38.26 ± 5.7). The mean values of hybrid layer thickness (MPa ± dp: 48hours / 6meses / year) were: SalSB (3.59 ± 0.8, 3.59 ± 1.0, 2.08 ± 1.5). SalSU (1.26 ± 0.5, 1.73 ± 0.8, 1.07 ± 0.3). The values of degree of conversion (MPa ± dp: 10% / 25% / 50% vol) were: SB (85.59 ± 3.4, 49.68 ± 12.8, 38.56 ± 11.8); (85.52 ± 3.3, 86.27 ± 3.5, 57.82 ± 11.1). It was therefore concluded that human saliva contamination did not interfere on bond strength of the dentin/adhesive interface after 48 hours, 6 months and 12 months. The morphology of the hybrid layer was altered by the presence of saliva after 6 and 12 months. The degree of conversion of adhesive systems was affected by the presence of saliva immediately after polymerization. However, the time factor was determinant for the dentine/resin interface deformation for both adhesive systems.(AU)

Evaluation of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental dental resin-based materials

ABSTRACT Objective To evaluate the influence of phenyl-propanedione on yellowing and chemical-mechanical properties of experimental resin-based materials photoactivated using different light curing units (LCUs). Material and Methods Experimental resin-based materials with the same organic matrix (60:40 wt% BisGMA:TEGDMA) were mechanically blended using a centrifugal mixing device. To this blend, different photoinitiator systems were added in equimolar concentrations with aliphatic amine doubled by wt%: 0.4 wt% CQ; 0.38 wt% PPD; or 0.2 wt% CQ and 0.19 wt% PPD. The degree of conversion (DC), flexural strength (FS), Young’s modulus (YM), Knoop hardness (KNH), crosslinking density (CLD), and yellowing (Y) were evaluated (n=10). All samples were light cured with the following LCUs: a halogen lamp (XL 2500), a monowave LED (Radii), or a polywave LED (Valo) with 16 J/cm2. The results were analysed by two-way ANOVA and Tukey’s test (α=0.05). Results No statistical differences were found between the different photoinitiator systems to KNH, CLS, FS, and YM properties (p≥0.05). PPD/CQ association showed the higher DC values compared with CQ and PPD isolated systems when photoactivated by a polywave LED (p≤0.05). Y values were highest for the CQ compared with the PPD systems (p≤0.05). Conclusion PPD isolated system promoted similar chemical and mechanical properties and less yellowing compared with the CQ isolated system, regardless of the LCU used.

Effects of the application techniques of self-adhesive resin cements on the interfacial integrity and bond strength of fiber posts to dentin

ABSTRACT Objective: To evaluate the influence of an application technique of a glass-fiber post using self-adhesive resin cements on the push-out bond strength and the presence of bubbles in the root thirds. The cements were either applied according to the manufacturer's instruction or using a commercial delivering system (Centrix), at which the cement pastes were collected and applied after manipulation. Material and Methods: Self-adhesive resin cements (RelyX U200/3M ESPE-U200; Maxcem Elite/Kerr-MAX; Clearfil SA Cement/Kuraray-CSA) and a conventional cement (RelyX ARC/3M ESPE-ARC) were used to cement a post and applied either based on the manufacturer's instructions or using a Centrix syringe to deliver the cements directly onto the post of choice, or directly into canal. The roots were scanned with a micro-computed tomography (μCT) and then sectioned into nine 1-mm thick slices for a push-out bond strength test. The μCT images showed the percentage of bubbles in the root thirds (cervical, medium, and apical). Data were analyzed with three-way ANOVA/Tukey (α=0.05). Results: Triple interaction was not significant (p>0.05). The interaction “material” vs “root third” was not significant. A significant interaction was observed between “material” vs “application technique” (p<0.05). For ARC, U200, and MAX, significantly lower percentages of bubbles were observed when the Centrix syringe delivered the cements. Equivalent percentages of voids were observed for CSA, irrespective of the application technique (p>0.05). Significantly higher bond strength was observed when the self-adhesive resin cements were applied using the Centrix delivery system, in comparison with the manufacturer's instructions (p<0.05). Bond strength varied with the root third: cervical>medium>apical (p<0.05). No correlations were found between the bond strength and voids. Conclusions: Bond strength and voids are negatively influenced by the conventional application technique for luting fiber posts. The delivery system (Centrix) seems to produce better results when cementing fiber posts.