Prevalence of lectures about dental esthetics and female speakers in three Brazilian conferences

Abstract This study analyzed the prevalence of lectures involving esthetics in the scientific program of Brazilian dental conferences and the gender distribution of speakers. All lectures presented in three dental conferences (Bahia, São Paulo, and Goiás states) held from 2016 to 2020 were evaluated. Three investigators individually divided the lectures according to the specialties recognized by the Brazilian Federal Council of Dentistry (FCD) based on their titles. The lectures were also classified as involving or not esthetics, and the speaker`s gender was recorded. Descriptive statistical analyses were performed, and Chi-square tests assessed possible associations between factors. The words most cited in the titles of the lectures were "esthetic" (13.6%), "dentistry" (9.9%), and "treatment" (8.1%). Oral diseases were barely mentioned in the titles (up to 1.3%). The highest number of lectures was observed for the specialty of Restorative Dentistry (22.3%), followed by Prosthodontics (18.5%). Approximately one-third of lectures involved some aesthetic aspect, but this percentage ranged from 71.9 to 78.6% for the two specialties with more lectures. Regarding the speaker`s gender, the inequity was higher for lectures involving esthetics (81.6% of males) than for topics unrelated to esthetics (66.7%). More male speakers than females were observed for all specialties. The highest gender gap was observed for Pediatric Dentistry with 62.4% male speakers, although only 10.6% of FCD registered specialists were men. In conclusion, the Brazilian dental conferences analyzed seemed to favor offering lectures dealing with esthetic topics and male speakers.

Resumo Este estudo analisou a prevalência de palestras envolvendo estética na programação científica de congressos de Odontologia brasileiros, e a distribuição do gênero dos palestrantes. Todas as palestras apresentadas em três congressos de Odontologia (CIOBA, CIOGO, and CIOSP) entre 2016 e 2020 foram avaliadas. Três avaliadores utilizaram os títulos das palestras para dividi-las entre as especialidades reconhecidas pelo Conselho Federal de Odontologia (CFO) do Brasil. As palestras foram também classificadas como envolvendo ou não estética, e o gênero do palestrante foi registrado. Análises estatísticas descritivas foram realizadas, e testes de Qui-quadrado avaliaram possíveis interações entre fatores. A palavra mais citada nos títulos das palestras foi "estética" (13,6%), seguido por "odontologia" (9,9%) e "tratamento" (8,1%). Doenças orais foram raramente mencionadas nos títulos (até 1,3%). O maior número de palestras foi observado para a especialidade de Dentística (22,3%), seguido por Prótese Dental (18,3%). Aproximadamente um terço das palestras envolviam algum aspecto estético, com porcentagens entre 71,9 a 78,6% para as duas especialidades com mais palestras. Em relação ao gênero do palestrante, a inequidade foi maior para palestras envolvendo estética (81,6% de homens) que para tópicos não relacionadas à estética (66,7%). Mais palestrantes do sexo masculino que feminino foram observados para todas as especialidades. A maior discrepância entre os gêneros foi observada para Odontopediatria, uma especialidade com 62,4% dos palestrantes do sexo masculino, embora apenas 10,6% dos especialistas registrados no CFO eram homens. Como conclusão, os congressos de Odontologia Brasileiros parecem preferir palestras abordando tópicos de estética e palestrantes do sexo masculino.

Impact of COVID-19 on gender gap in dental publications: a retrospective cohort with three Brazilian journals

Abstract This was a retrospective cohort study to investigate the impact of COVID-19 pandemic on the gender gap in articles submitted to three international dental journals based in Brazil. All submissions performed to Brazilian Dental Journal, Brazilian Oral Research, and Journal of Applied Oral Science before (2019) and during the pandemic (2020) were assessed. Gender of the first, last, and corresponding authors were collected. Other variables collected were journal, continent studied by authors and stage of their careers (classified according to authors' highest degree), and final decision reached in the article. Absolute and relative frequencies with 95% confidence intervals, Pearson's Chi-square tests, and Fisher's Exact test were used (α = 0.05). In total, 4,726 unique submissions were analyzed. A higher proportion of early-career authors was observed during the pandemic (44.8% to 49.3%, p = 0.021). Most articles were rejected but without association with gender. Increased proportion of male first authors from before to during the pandemic was observed (39% to 42.1%, p = 0.034). Drop in the proportion of articles with women as first authors was observed for researchers in their early- (65.9% to 58.8%, p = 0.02) and mid-career stages (63% to 55.8%, p = 0.014). Reduction in women as first authors was observed during the pandemic in South and Central Americas (66.7% to 61.5%, p = 0.010), and when the last author was a female, or the corresponding author was a male. In conclusion, a disproportionate impact on female dental researchers in submitting articles in the period from before to during the pandemic was observed when considering first authorship, suggesting that the COVID-19 may have increased the gender inequality in dental science.

Polywave And Monowave Light-Curing Units Effects On Polymerization Efficiency Of Different Photoinitiators / Efeito Da Unidade De Cura Por Luz Polywave E Monowave Na Eficiência De Polimerização De Diferentes Fotoiniciadores

Objective: The objective of this study was to characterize and correlate the absorption spectra of three photoinitiators [camphorquinone (CQ), diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO) and phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide (BAPO)], using second or third-generation light curing units (LCU), and to evaluate the degree of conversion and the physical properties of an experimental resin adhesive. Material and methods: Second-generation (Radii-cal® and Emitter D®) and third-generation (Valo® Cordless and Bluephase N®) LCU were assessed regarding spectrum and irradiance rate of emitted light. Also, the photoinitiators (CQ, TPO and BAPO) were characterized by a light absorption spectrum assessed by UV-Vis spectroscopy, degree of conversion and yellowing effect. Statistical analyzes considered two-way ANOVA and post-hoc Tukey test. Results: BAPO presented higher reactivity compared to TPO. Regarding degree of conversion of the photoinitiators activated by different light-curing units, the Emitter D® device promoted a high degree of conversion. BAPO presented the highest yellowing effect values. Conclusions: The emission and absorption characteristics of the photoinitiators were different. The polymerization reaction activated by the second-generation light-curing unit was reduced when using an experimental resin with photoinitiator TPO, and the third-generation light-curing unit showed a higher polymerization potential regardless of the photoinitiator. (AU)

Objetivo: Caracterizar e correlacionar os espectros de absorção de três fotoiniciadores [canforoquinona (CQ), difenil 2,4,6-trimetilbenzil óxido de fosfina (TPO) e óxido de di (2,4,6-trimetilbenzil) difenil fosfina (BAPO)], com unidades de fotoativação (LCU) de segunda ou terceira geração, e avaliar o grau de conversão e as propriedades físicas de um adesivo experimental. Material e métodos: LCU de segunda geração (Radii-cal® e Emitter D®) e terceira geração (Valo® Cordless e Bluephase N®) foram avaliadas quanto ao espectro e taxa de irradiância da luz emitida. Além disso, os fotoiniciadores (CQ, TPO e BAPO) foram caracterizados por um espectro de absorção de luz avaliado por espectroscopia UV-Vis, avaliado o grau de conversão dos adesivos e efeito de amarelamento. A análise estatística empregada foi ANOVA duas vias e teste post-hoc de Tukey. Resultados: BAPO apresentou maior reatividade comparado ao TPO. Em relação ao grau de conversão dos fotoiniciadores ativados por diferentes aparelhos fotopolimerizadores, o dispositivo Emitter D® promoveu um alto grau de conversão. BAPO apresentou os maiores valores de efeito de amarelamento. Conclusões: As características de emissão e absorção dos fotoiniciadores foram diferentes. A reação de polimerização ativada pelas unidades de fotopolimerização de segunda geração foi reduzida com o uso de uma resina experimental com fotoiniciador TPO. As unidades de fotopolimerização de terceira geração apresentaram maior potencial de polimerização independentemente do fotoiniciador. (AU)

A Bibliometric analysis of articles published in Brazilian Dental Journal over 30 years

Abstract This study assessed bibliometric characteristics of all articles published in Brazilian Dental Journal (BDJ) in its 30 years of existence (1990-2019) and factors associated with citation rates. A document search was carried out in Scopus in December, 2019 and information about the articles were exported, including citations. Type of study and main subject in each article were categorized. Number of citations was categorized in tertiles. Logistic regression models were used to assess the association between variables related to articles' characteristics and number of citations. In 30 years, 1705 articles were published and 18507 citations received, with average 57 articles and 334 pages published yearly and 10.9 cites/doc. The most frequent types of study were laboratorial (63%), clinical (18.5%), and case reports (11%); the main subjects were dental materials (21.6%), endodontics (19.3%), and oral pathology/stomatology (13.1%). Most articles had origin in Brazil (90%), followed by USA (4.6%) and UK (1.5%). Aside from BDJ, Journal of Endodontics (3.5%) and International Endodontic Journal (2.2%) were journals that most often cited BDJ. Main origins of citations were Brazil (36.7%), USA (10.6%), and India (9%). Older articles had higher odds to be highly cited (12% increase/year), longer articles had lower odds (9% decrease/page). Narrative reviews and epidemiological studies were associated with more citations and systematic reviews with less citations. In conclusion, BDJ covered many subjects and study types in 30 years, showing increased growth in international audience. The journal may be regarded as one of the leading Brazilian journals in dentistry published in English.

Resumo Este estudo avaliou as características bibliométricas de todos os artigos publicados no Brazilian Dental Journal (BDJ) em seus 30 anos de existência (1990-2019) e fatores associados com taxas de citação. Uma busca pelos documentos foi realizada no Scopus em Dezembro de 2019 e informações acerca dos artigos foram exportadas, incluindo citações. Tipo de estudo e principal assunto em cada artigo foram categorizados. Número de citações foi categorizado em tercis. Modelos de regressão logística foram usados para avaliar a associação entre as variáveis relacionadas às características dos artigos e o número de citações. Em 30 anos, 1705 artigos foram publicados e 18507 citações recebidas, com média de 57 artigos e 334 páginas publicadas ao ano e 10,9 citações/documento. Os tipos de estudo mais frequentes foram laboratorial (63%), clínico (18,5%) e relato de caso (11%); os principais assuntos foram materiais dentários (21,6%), endodontia (19,3%) e patologia oral/estomatologia (13,1%). A maioria doas artigos teve origem do Brasil (90%), seguido dos EUA (4,6%) e Reino Unido (1,5%). Além do BDJ, Journal of Endodontics (3,5%) e International Endodontic Journal (2,2%) foram os periódicos que mais citaram o BDJ. As principais origem das citações foram Brasil (36,7%), EUA (10,6%) e Índia (9%). Artigos mais antigos tiveram maiores chances de serem altamente citados (aumento de 12% ao ano), artigos mais longos tiveram menores chances (redução de 9% por página). Revisões narrativas e estudos epidemiológicos foram associados com mais citações e revisões sistemáticas com menos citações. Em conclusão, o BDJ cobriu diversos assuntos e tipos de estudo em 30 anos, mostrando contínuo crescimento na audiência internacional. O periódico pode ser considerado um dos líderes entre as revistas brasileiras de odontologia publicadas em inglês.

Simple and low-cost thermal treatments on direct resin composites for indirect use

Abstract The aim of this study was to evaluate the influence of three low-cost additional thermal treatments, available in the dental office, on the mechanical, chemical and optical properties of a light-cured resin composite indicated for direct restorations but used as indirect restorative. The direct resin composite TPH3 (Dentsply) was light-polymerized using a light-emitting diode curing unit and submitted to three experimental additional thermal treatments: dry heat at 170 °C for 5 min, autoclave at 121 °C for 6 min, or microwave oven at 450 W for 3 min. The resin composite without any thermal treatment was used as negative control group. An indirect resin composite (Vita CM LC, Vita Zahnfabrik) was tested as a reference. Flexural strength, elastic modulus, microhardness, degree of C=C conversion, roughness before and after simulated toothbrush abrasion, translucency parameter and color difference (ΔE00) were evaluated. Data were analyzed at α=0.05. The indirect resin composite presented lower C=C conversion and mechanical performance. The flexural strength was significantly higher in the dry oven group compared with the control. The roughness was not different among groups before or after brushing, but the thermal treatments caused an increase in C=C conversion, microhardness, and elastic modulus without affecting the translucency parameter or showing visible color alteration (ΔE00<1.8). These results suggest that the use of additional thermal methods of polymerization represents an economical and simple alternative to enhance the mechanical and chemical properties of direct resin composites when used as indirect restoratives.

Resumo O objetivo deste estudo foi avaliar a influência de três tratamentos térmicos adicionais de baixo custo, disponíveis no consultório dentário, nas propriedades mecânicas, químicas e ópticas de uma resina composta fotoativada indicada para restaurações diretas porém usada como restaurador indireto. A resina composta direta TPH3 (Dentsply) foi fotoativada usando um diodo emissor de luz e submetida a três tratamentos térmicos adicionais experimentais: forno seco a 170 °C por 5 min, autoclave a 121 °C por 6 min ou forno de micro-ondas a 450 W por 3 min. A resina composta sem qualquer tratamento térmico adicional foi usada como grupo controle negativo. Uma resina composta indireta (Vita CM LC, Vita Zahnfabrik) foi testada como referência comercial. Resistência à flexão, módulo de elasticidade, microdureza, grau de conversão de C=C, rugosidade antes e após abrasão por escovação simulada, parâmetro de translucidez e diferença de cor (ΔE00) foram avaliados. Os dados foram analisados considerando α=0.05. A resina composta indireta apresentou menor conversão de C=C e desempenho mecânico. A resistência à flexão foi significativamente mais alta no grupo forno seco comparado ao controle. A rugosidade não foi diferente entre os grupos antes ou após a escovação, porém os tratamentos térmicos adicionais causaram aumento na conversão de C=C, microdureza e módulo de elasticidade, sem afetar o parâmetro de translucidez ou mostrar alteração de cor visível (ΔE00<1,8). Estes resultados sugerem que o uso de métodos térmicos adicionais de polimerização representam alternativa econômica e simples para aprimorar as propriedades mecânicas e químicas de resinas compostas diretas quando utilizadas como restauradores indiretos.

Top-100 most cited dental articles with authors from Brazil

Abstract This study analyzes the characteristics of the top-100 most cited articles published in international dental journals with at least one coauthor affiliated to Brazil. A search in Scopus database for articles published between 1996 and 2017 was carried out in the 178 journals belonging to the category "Dentistry" identified in SCImago Journals & Country Rank. From the top-100 most cited articles, variables related to the journal, article, and authors were collected. Annual citation averages (ACA) and relative citation ratios (RCR) were calculated. Data were analyzed descriptively. There were 75 original reports and 25 reviews in the sample. The number of citations ranged between 124 and 657 (mean=202, median=168). The papers were published in 31 different journals (46% in only four journals), none based in Brazil. The most frequent subjects (61%) were Dental Materials, Endodontics, and Periodontology, which accounted for 63.6% of the total citations. The subject with the highest ACA was Oral and Maxillofacial Surgery and the subject with the highest RCR was Oral Radiology. Only 12 articles were cited more than 300 times. International collaboration was present in 61 articles and funding was reported in 49 articles. The first author was from Brazil in 70% and corresponding author in 55% of the papers. Southeast (83%) and South (20%) were the regions of Brazil with most presence of coauthors. This top-100 list is presented to provide an overview of the most cited articles and aid in supporting further analyses regarding publication and citation behaviors of Brazilian dentistry.

Resumo Este artigo analisa as características dos 100 artigos mais citados publicados em periódicos internacionais de odontologia com ao menos um co-autor afiliado ao Brasil. Uma busca na base de dados Scopus por artigos publicados entre 1996 e 2017 foi realizada nos 178 periódicos pertencentes à categoria "Dentistry" identificados no SCImago Journals & Country Rank. Dos 100 artigos mais citados, variáveis relacionadas ao periódico, artigo e autores foram coletadas. Médias anuais de citação (MAA) e razões de citação relativa (RCR) foram calculadas. Os dados foram analisados descritivamente. A amostra foi composta por 75 artigos originais e 25 revisões. O número de citações variou entre 124 e 657 (média=202, mediana=168). Os artigos foram publicados em 31 periódicos diferentes (46% em apenas quatro periódicos), nenhum do Brasil. Os temas mais frequentes (61%) foram Materiais Dentários, Endodontia e Periodontia, somando 63,6% do total de citações. O tema com maior MAA foi Cirurgia Oral e Maxilofacial e o tema com maior RCR foi Radiologia Oral. Apenas 12 artigos foram citados mais de 300 vezes. Colaboração internacional estava presente em 61 artigos e financiamento foi reportado em 49 artigos. O primeiro autor era do Brasil em 70% e o correspondente em 55% dos artigos. As regiões do Brasil com mais co-autores presentes foram Sudeste (83%) e Sul (20%). Esta lista é apresentada para prover uma fotografia dos 100 artigos mais citados e ajudar a fomentar análises posteriores em relação a comportamentos de citação e publicação da odontologia brasileira.

Long-term bonding efficacy of adhesives containing benzodioxioles as alternative co-initiators

Abstract This study evaluated the three-year lifespan of the bond to dentin of experimental self-etch adhesives containing benzodioxole derivatives - 1,3-benzodioxole (BDO) and piperonyl alcohol (PA) - as co-initiator alternative to amines. Adhesive resins were formulated using Bis-GMA, TEGDMA, HEMA, camphorquinone and different co-initiators: BDO, PA or ethyl 4-dimethylamino benzoate (EDAB - amine). An experimental self-etch primer was used to complete the two-step, self-etch adhesive system. Clearfil SE Bond (CSE) was used as commercial reference. Bond strength to human dentin was assessed by microtensile bond strength (µTBS) test, and failure mode was classified. Morphology of the dentin bonding interface was assessed via scanning electron microscopy (SEM). Irrespective of the dental adhesives evaluated, µTBS was higher after 24 hours compared with that after 1.5 and 3 years (p ≤ 0.001). However, adhesives with BDO and PA as co-initiators showed significantly higher bond strength than the bonding resin with EDAB (p ≤ 0.002), independent of the time evaluated. The commercial adhesive CSE showed similar bond strength compared with the other groups (p ≥ 0.05). Mixed failures were mainly observed after 24 hours, while adhesive failures were more frequently observed after 1.5 and 3 years. No notable differences in homogeneity and continuity along the bonded interfaces were detected among the materials in the SEM analysis. In conclusion, benzodioxole derivatives are feasible alternative co-initiators to tertiary amine in camphorquinone-based self-etching dental adhesive formulations.

Inorganic filler content of resin-based luting agents and the color of ceramic veneers

Abstract The influence of inorganic filler content of resin-based luting agents (RBLAs) on color change (ΔE00), CIEL*a*b* (individual color coordinates), and translucency parameters (TP) of simulated ceramic laminate veneer (CLV) was investigated. RBLAs with low, intermediate, and high inorganic filler content (55%, 65%, and 75% mass fractions, respectively) were prepared. Feldspar ceramic (Vitablocs Mark II) specimens (1.2 mm × 0.8 mm, A1C shade) were bonded to simulated composite resin substrates (1.6 mm × 1.2 mm, A2D shade) using three experimental and a commercial (RelyX Veneer) RBLA (translucent shade). The ΔE00 was calculated by CIEDE2000 color difference metric under three conditions (before, immediately after, and 24 h after luting). The TP was calculated using CIEL*a*b* color coordinates measured over white and black backgrounds. Surface morphology of the RBLAs was analyzed. One-way and two-way analyses of variance with a post-hoc Tukey's test were used respectively to calculate TP, CIEL*a*b* coordinates, and ΔE00 (α= 0.05). Overall, the tested RBLAs presented clinically visible ∆E00 values under the three conditions evaluated. For all RBLAs, higher ∆E00 values were observed between measurements obtained before and immediately after luting. Different inorganic filler content did not significantly increase the opacity of the ceramic-luting agents-resin composite set. The variation in inorganic filler content did not influence significantly the TP of simulated CLV; although all of the experimental RBLAs tested yielded ∆E00 above the perceptibility threshold. The L*, a*, and b* individual color coordinates were cementation-dependent.

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.

Should my composite restorations last forever? Why are they failing?

Abstract Composites resins have become the first choice for direct anterior and posterior restorations. The great popularity is related to their esthetic appearance and reduced need of sound tissue removal as compared with former treatments. Several studies have demonstrated that composite restorations may last long in clinical service. In this review we discuss the factors playing a role on the long-term longevity. Composite restorations have demonstrated a good clinical performance with annual failure rates varying from 1% to 3% in posterior teeth and 1% to 5% in anterior teeth. Factors related to the patients such as caries risk and occlusal stress risk, in addition to socioeconomic factors, may affect the survival significantly. Characteristics of the clinical operators, particularly their decision making when it comes to observing or approaching an existing restoration, are decisive for longevity. Cavity features such as the number of restored walls, composite volume, and presence of endodontic treatment are of major importance and may dictate the service time of the restorative approach. The choice of restorative composite seems to have a minor effect on longevity provided that appropriate technical procedures are used. The main reasons for failure in posterior teeth are secondary caries and fracture (restoration or tooth/restoration), while in anterior teeth esthetic concerns are the main reasons leading to restoration failures. Composite resin restorations can be considered a reliable treatment as long as both the professional and the patient are aware of the factors involved in restoration failures.

Restabelecimento funcional e estético com coroas e facetas laminadas / Functional and aesthetic reestablishment with full crowns and laminate veneers ­ a case report

A adequada estética do sorriso é cada vez mais almejada pelo paciente e pelo profissional. Dentes escurecidos e com lesões de abfração, causadas por excessiva carga oclusal, desfavorecem o agradável aspecto dos dentes e a estética facial como um todo. Este caso clínico relatou o procedimento restaurador de dentes anteriores superiores que apresentavam cor e forma inadequadas. Foram confeccionadas facetas e coroas com cerâmica termoprensada reforçada por dissilicato de lítio (IPS e.max Press, Ivoclar), que tem sido frequentemente utilizada na confecção de restaurações em dentes anteriores e posteriores por apresentar propriedades estéticas e mecânicas satisfatórias. Após a reabilitação, pôde-se perceber que o detalhado planejamento do tratamento e a correta escolha do material restaurador resultaram no restabelecimento funcional e estético. Foi possível concluir que restaurações obtidas a partir da cerâmica de dissilicato de lítio mostraram ser uma ótima alternativa para a confecção de facetas e coroas, considerando que houve perfeita concordância de cor entre ambas as restaurações, resultando no sucesso do tratamento e satisfação do paciente.

Adequate aesthetic appearance of the smile is increasingly desired by patient and professional. Darkened teeth and abfraction injuries caused by excessive occlusal load jeopardizes the appearance of the teeth, and the facial aesthetics as a whole. This case describes the restorative treatment of upper anterior teeth that presented inadequate color and form. Crowns and laminate veneers were made with lithium disilicate ceramic, which has often been used in the fabrication of anterior tooth restorations because it presents satisfactory aesthetic and mechanical properties. After the restorative process, it can be concluded that the detailed treatment planning and the correct choice of restorative material result in the reestablishment of function and aesthetics. It was concluded that the lithium disilicate ceramic showed to be an excellent alternative for making laminate veneers and adjacent crowns, considering that there was perfect color matching between both restorations, resulting in the success of treatment and patient satisfaction.

An alternative specimen preparation technique for 3-point bending tests on dual-cured dental resin cements / Técnica alternativa de confecção de espécimes para testes de flexão de 3 pontos em cimentos de resina dentária de dupla ativação

The proper mechanical properties of resin cements are essential to the longevity of indirect restoration, whereas the 3-point bending test is recommended for measuring the flexural strength. The ISO 4049 specification requires light-curing of specimens in three consecutive points; however, this approach cannot be used for dual-cured resin cements. The aim of this study was to investigate the effect of two different specimen preparation techniques on the flexural strength and elastic modulus of experimental dual-cured resin cements immediately or 5 after minutes light curing. Experimental dual-cured resin cements were formulated, and the specimens of these cements were confectioned with the dimension of ISO 4049 specification. Light-activation was performed at one or three points immediately or 5 minutes after the insertion of cement into the matrix (n=7), resulting in four experimental conditions (2 methods × 2 moments of light-activation). The three-point bending test was performed and the values of the flexural strength and elastic modulus were recorded. Data were individually analyzed using 2-way ANOVA followed by the Tukey's post hoc test (P<0.05). Regardless of the points of light-activation, the specimens that were light-cured at 3 points showed the highest values of flexural strength. Only for light-activation at 1 point did the time before the light-activation affect the elastic modulus, whereas delayed light-activation had the highest values. In conclusion, the number of lightcuring points on specimen preparation for the 3-point bending test seems to affect the mechanical properties of dual-cured resin cements.

Cimentos resinosos com propriedades mecânicas adequadas são essenciais para a longevidade de restaurações indiretas, sendo que o ensaio de flexão de 3 pontos é recomendado para mensurar a resistência flexural. A especificação ISO 4049 requer a fotoativação das amostras em três pontos consecutivos, entretanto, esta abordagem não pode ser usada para cimentos resinosos duais. O objetivo deste estudo foi investigar o efeito e duas diferentes técnicas de preparo de amostras na resistência flexural e módulo de elasticidade de cimentos resinosos duais experimentais fotoativados imediatamente ou após 5 minutos. Cimentos resinosos duais experimentais foram formulados, e amostras destes cimentos foram confeccionadas com as dimensões da especificação ISO 4049. A fotoativação foi realizada em um ou três pontos imediatamente ou após 5 minutos da inserção do cimento na matriz (n=7), resultando em quatro condições experimentais (2 métodos × 2 tempos antes da fotoativação). O teste de flexão de três pontos foi realizado e os valores de resistência flexural e módulo de elasticidade mensurados. Os dados foram individualmente analisados por ANOVA de dois fatores seguido pelo teste de Tukey (P<0,05). Em relação aos pontos de fotoativação, as amostras que foram fotoativadas em três pontos mostraram os maiores valores de resistência flexural. Apenas para a fotoativação em um ponto, o tempo antes da fotoativação afetou o módulo de elasticidade, sendo que a fotoativação tardia apresentou maiores valores. Em conclusão, o número de pontos de fotoativação no preparo das amostras para teste de flexão de 3 pontos parece afetar as propriedades mecânicas dos cimentos resinosos.

Acid Etching and Surface Coating of Glass-Fiber Posts: Bond Strength and Interface Analysis

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.

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.

Effect of filling technique on the bond strength of methacrylate and silorane-based composite restorations

Abstract The bond strength of methacrylate (Z350, 3M ESPE) and silorane (P90, 3M ESPE) restorations, using different cavity filling techniques, was investigated. Cavities (6 × 3 × 3) in bovine teeth were filled using bulk, oblique, or horizontal increments. A push-out test was carried out after 24 h. Data were statistically analyzed (α = 5%). Methacrylate-based composites and the horizontal filling technique showed the highest bond strength values (10.2 ± 3.9, p < 0.05). Silorane-based composites showed no statistically significant differences regarding the filling techniques (p > 0.05).

Effectiveness of Combination of Dentin and Enamel Layers on the Masking Ability of Porcelain

This study evaluated the masking ability of different porcelain thicknesses and combination of enamel and/or dentin porcelain layers over simulated background dental substrates with higher (A2) and lower (C4) color values. Combination of the enamel (E) and dentin (D) monolayer porcelain disks with different thicknesses (0.5 mm, 0.8 mm, and 1 mm) resulted in the following bilayer groups (n=10): D1E1, D1E0.8; D1E0.5; D0.8E0.8; D0.8E0.5, and D0.5E0.5. CIELAB color coordinates were measured with a spectrophotometer. The translucency parameter of mono and bilayer specimens and the masking ability estimated by color variation (ΔE*ab) of bilayer specimens over simulated dental substrates were evaluated. Linear regression analysis was used to investigate the relationships translucency parameter × ΔE*, translucency parameter × porcelain thickness, and ΔE* × porcelain thickness. Data were analyzed statistically (α= 0.05). Thinner porcelain disks were associated with higher translucency. Porcelain monolayers were considerably more translucent than bilayers (enamel + dentin). Dentin porcelain was less translucent than enamel porcelain with same thickness. ΔE* was always lower when measured over A2 background. Higher ΔE* was observed for the C4 background, indicating poorer masking ability. Increased ΔE* was significantly associated with increased translucency for both backgrounds. Decreased translucency and ΔE* were associated with increased total porcelain thickness or increased dentin thickness for both backgrounds. In conclusion, increased porcelain thickness (particularly increased dentin layer) and increased porcelain opacity resulted in better masking ability of the dental backgrounds.

Resumo Este estudo avaliou a capacidade de mascaramento de diferentes espessuras de porcelana e a combinação de camadas de porcelana de esmalte e/ou de dentina sobre substratos dentais simulados de fundo com cores de maior (A2) e menor (C4) valor. Combinação de discos de porcelana em monocamadas de esmalte (E) e dentina (D) com diferentes espessuras (0,5 mm, 0,8 mm e 1 mm) resultou nos seguintes grupos bicamadas (n=10): D1E1, D1E0,8; D1E0,5; D0,8E0,8; D0,8E0,5 e D0,5E0,5. Coordenadas de cor CIELAB foram mensuradas com um espectrofotômetro. O parâmetro de translucidez de espécimes mono e bicamadas e a capacidade de mascaramento estimada pela variação de cor (ΔE*ab) dos espécimes bicamadas sobre os substratos dentais simulados foram avaliados. Análise de regressão linear foi utilizada para investigar as relações parâmetro de translucidez x ΔE*, parâmetro de translucidez x espessura da porcelana, e ΔE* x espessura da porcelana. Os dados foram analisados estatisticamente (α=0,05). Discos de porcelana mais finos foram associados a maior translucidez. Monocamadas de porcelana foram consideravelmente mais translúcidas que bicamadas (esmalte + dentina). Porcelana de dentina foi menos translúcida que porcelana de esmalte com mesma espessura. ΔE* foi sempre menor quando mensurado sobre fundo A2. Maior ΔE* foi observado para o fundo C4, indicando pior capacidade de mascaramento. Maior ΔE* foi significativamente associado à maior translucidez para ambos fundos. Menor translucidez e ΔE* foram associados ao aumento da espessura total da porcelana ou aumento da espessura de dentina para ambos fundos. Em conclusão, aumento da espessura da porcelana (particularmente aumento da camada de dentina) e aumento da opacidade da porcelana resultaram em melhor capacidade de mascaramento dos fundos dentários.

A Modified Photoactivation Protocol Using Two Simultaneous Light-Curing Units for Bonding Brackets to Enamel

This study investigated the effect of a modified photoactivation protocol using two simultaneous light-curing units on the shear bond strength (SBS) of brackets to enamel. Metal brackets were bonded to bovine incisors using the resin-based orthodontic cement Transbond XT (3M Unitek). Four photoactivation protocols of the orthodontic cement were tested (n=15): Control: photoactivation for 10 s on each proximal face of the bracket at a time; Simultaneous: photoactivation for 10 s on both proximal faces of the bracket at the same time; One side-20s: photoactivation for 20 s at one proximal face of the bracket only; and One side-10s: photoactivation for 10 s only at one proximal face of the bracket. SBS was tested immediately or after 1000 thermal cycles. Adhesive remnant index (ARI) was classified. Data were subjected to two-way ANOVA and Student-Newman-Keuls' test (α=0.05). Pooled means ± standard deviations for SBS to enamel (MPa) were: 10.2±4.2 (Control), 9.7±4.5 (Simultaneous), 5.6±3.1 (One side-20s), and 4.6±1.9 (One side-10s). Pooled SBS data for immediate and thermal cycled groups were 6.3±2.6 and 8.8±5.2. A predominance of ARI scores 1-2 and 0-1 was observed for the immediate and thermally cycled groups, respectively. In conclusion, simultaneous photoactivation of the orthodontic cement using two light-curing units, one positioned at each proximal face of the bracket, yielded similar bonding ability compared to the conventional light-curing method. Photoactivation of the orthodontic cement at one proximal face of the bracket only is not recommended, irrespective of the light-curing time used.

Este estudo investigou o efeito de um protocolo modificado de fotoativação utilizando duas unidades de fotopolimerização simultâneas na resistência de união ao cisalhamento (RUC) de braquetes ao esmalte. Braquetes metálicos foram fixados a incisivos bovinos utilizando o cimento ortodôntico resinoso Transbond XT (3M Unitek). Quatro protocolos de fotoativação do cimento ortodôntico foram testados (n=15): Controle: fotoativação por 10 s em cada face proximal do braquete de cada vez; Simultâneo: fotoativação por 10 s em ambas as faces proximais do braquete ao mesmo tempo; Um lado-20s: fotoativação por 20 s em uma face proximal do braquete apenas; e Um lado-10s: fotoativação por 10 s apenas em uma face proximal do braquete. A RUC foi testada imediatamente ou após 1000 ciclos térmicos. O Índice de Remanescente de Adesivo (IRA) foi classificado. Os dados foram submetidos a ANOVA de duas vias e teste de Student-Newman-Keuls (α=0,05). As médias agrupadas ± desvios-padrão de RUC ao esmalte (MPa) foram: 10,2±4,2 (Controle), 9,7±4,5 (Simultâneo), 5,6±3,1 (Um lado-20s), e 4,6±1,9 (Um lado-10s). Os dados agrupados de RUC para os grupos imediatos e termociclados foram 6,3±2,6 e 8,8±5,2. Predominância de escores IRA 1-2 e 0-1 foi observada para os grupos imediatos e termociclados, respectivamente. Em conclusão, a fotoativação simultânea do cimento ortodôntico utilizando duas fontes de luz, uma posicionada em cada face proximal do braquete, gerou similar capacidade de união ao método convencional de fotopolimerização. Fotoativação do cimento ortodôntico em apenas uma face proximal do braquete não é recomendada, independente do tempo de fotoativação utilizado.

A systematic review of factors associated with the retention of glass fiber posts

This study aimed to identify factors that can affect the retention of glass fiber posts to intra-radicular dentin based on in vitro studies that compared the bond strength (BS) of GFPs cemented with resin cements. Searches were carried out in PubMed and Scopus until December 2013. Bond strength values and variables as type of tooth, presence of endodontic treatment, pretreatment of the post, type of bonding agent (if present), type of cement and mode of cement application were extracted from the 34 included studies. A linear regression model was used to evaluate the influence of these parameters on BS. The presence of endodontic treatment decreased the BS values in 22.7% considering the pooled data (p = 0.013). For regular cement, cleaning the post increased BS when compared to silane application without cleaning (p = 0.032), considering cleaning as ethanol, air abrasion, or phosphoric acid application. Applying the cement around the post and into root canal decreased the resistance compared to only around the post (p = 0.02) or only into root canal (p = 0.041), on the other hand, no difference was found for self-adhesive resin cement for the same comparisons (p = 0.858 and p = 0.067). Endodontic treatment, method of cement application, and post pretreatment are factors that might significantly affect the retention of glass-fiber posts into root canals mainly when cemented with regular resin cement. Self-adhesive resin cements were found to be less technique-sensitive to luting procedures as compared with regular resin cements.

Effect of Composite Containing an Iodonium Salt on the Bond Strength of Brackets to Bovine Enamel

This study investigated the effect of the incorporation of an iodonium salt in experimental composites, on the bond strength of metallic brackets bonded to bovine teeth. Two hundred and seventy bovine teeth were embedded in self-curing acrylic resin and divided into 18 groups (n=15), according to the experimental composite with an iodonium salt at molar concentrations 0 (control), 0.5, or 1%; the light-activation times (8, 20 and 40 s); and the storage times (10 min or 24 h). Metallic brackets were fixed on the tooth surface using experimental composites. Photoactivation was performed with a quartz-tungsten-halogen light-curing unit curing unit for 8, 20 and 40 s. The specimens were stored in distilled water at 37 °C for 10 min or 24 h and submitted to bond strength test at 0.5 mm/min. The data were subjected to three-way ANOVA and Tukey's test (α=0.05). The Adhesive Remnant Index (ARI) was used to classify the failure modes. The shear bond strengths (MPa) at 10 min for light-activation times of 8, 20 and 40 s were: G1 - 4.6, 6.9 and 7.1; G2 - 8.1, 9.2 and 9.9; G3 - 9.1, 10.4 and 10.7; and at 24 h were: G1 - 10.9, 11.1 and 11.7; G2 - 11.8, 12.7 and 14.2; G3 - 12.1, 14.4 and 15.8. There was a predominance of ARI score 3 for groups with 10 min storage time, and ARI score 2 for groups with 24 h storage time. In conclusion, the addition of iodonium salt (C05 and C1) to the experimental composite may increase the bond strength of brackets to bovine enamel using reduced light exposure times.

Estudo investigou o efeito da incorporação de um sal de iodônio em compósito experimental, na resistência de união de braquetes metálicos fixados em dentes bovinos. Duzentos e setenta dentes bovinos foram embutidos e divididos em 18 grupos (n=15), de acordo com o compósito experimental com sal de iodônio na concentração molar de 0 (controle), 0,5 e 1 %; tempo de fotoativação (8, 20 e 40 s); e, tempo de armazenagem (10 min e 24 h). Braquetes metálicos foram fixados na superfície do dente usando compósitos experimentais. A fotoativação foi efetuada com o aparelho XL 2500 por 8, 20 e 40 s. As amostras foram armazenadas em água destilada a 37º C por 10 min e 24 h e submetidos ao ensaio de resistência de união à velocidade de 0,5 mm/min. Os dados foram submetidos à Análise de variância de 3 fatores e ao teste de Tukey (α=0,05). O Índice de Remanescente do Adesivo (IRA) foi usado para classificar os modos de falhas. Os valores de resistência de união ao cisalhamento (MPa) no período de 10 min para os tempos de fotoativação de 8, 20 e 40 s foram: G1 - 4,6; 6,9 e 7,1; G2 - 8,1; 9,2 e 9,9; G3 - 9,1; 10,4 e 10,7; e no período de 24 h foram: G1 - 10,9; 11,1 e 11,7; G2 - 11,8; 12,7 e 14,2; G3 - 12,1; 14,4 e 15,8. Houve predominância de escore 3 para os grupos armazenados por 10 min e escore 2 para os grupos armazenados por 24 h. Em conclusão, a adição do sal de iondônio (C05 e C1) em compósitos experimentais pode aumentar a resistência de união de braquetes ao esmalte bovino usando reduzidos tempos de fotoativação.

Effect of cariogenic challenge on the stability of dentin bonds

Objective: The oral environment is subject to biofilm accumulation and cariogenic challenge, and few studies exist on the effect of these factors on the bond strength of adhesive systems. The aim of this study was to test if the exposure of adhesive interfaces to cariogenic challenge under biofilm accumulation could promote higher degradation than the exposure to biofilm accumulation alone. Material And Methods: Five molars were ground until exposure of medium dentin and then restored (Single Bond 2 and Z250 3M ESPE). The tooth/resin sets were cut to obtain beam-shaped specimens, which were distributed according to the aging conditions (n=20): water for 24 h (control); biofilm under cariogenic challenge for 3, 5 or 10 days; biofilm without cariogenic challenge for 10 days; and water for 3 months. Microcosm biofilms were formed from human saliva and grown in a saliva analogue medium, supplemented or not with sucrose to promote cariogenic challenge. Specimens were tested for microtensile bond strength, and failure modes were classified using light microscopy. Bond strength data were analyzed using ANOVA and failure modes were analyzed using ANOVA on ranks (α=0.05). Results: No significant differences in bond strength were detected among the aging methods (P=0.248). The aging period was associated with an increase in the frequency of adhesive failures for the groups aged for 10 days or longer (P<0.001). Conclusion: Aging leads to a higher prevalence of interfacial adhesive failures, although this effect is not associated with cariogenic challenge or reduction in bond strengths. .

Intra-radicular dentin treatments and retention of fiber posts with self-adhesive resin cements

The aim of this study was to evaluate the effect of treating intraradicular dentin with irrigating solutions on the retention of glass-fiber posts luted with self-adhesive resin cement. Bovine incisors were endodontically treated, and 9-mm-deep postholes were prepared. Before inserting the cement, the root canals were irrigated with various solutions: 11.5% polyacrylic acid for 30 s, 17% EDTA for 60 s, or 5% NaOCl for 60 s, respectively. Irrigation with distilled water was used in the control group. After all specimens had been rinsed with distilled water, the excess moisture was removed and the posts were luted using either BisCem (Bisco) or RelyX Unicem clicker (3M ESPE). Seven days after luting, the specimens were sectioned transversally into 1-mm-thick slices, which were submitted to push-out testing on a mechanical testing machine. Bond strength data (n = 6 per group) were analyzed by two-way ANOVA and Student-Newman-Keuls' test (α = 0.05). For Unicem, EDTA showed lower bond strength than the other solutions, which had similar results. For BisCem, EDTA showed higher bond strength than the other treatments, while application of NaOCl yielded higher bond strength than polyacrylic acid whereas the control group had intermediate results. In conclusion, irrigating root canals before insertion of self-adhesive resin cements, especially EDTA, might interfere with retention of the fiber posts.