ABSTRACT
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.
Subject(s)
Humans , Benzyl Alcohols/chemistry , Dentin-Bonding Agents/chemistry , Resin Cements/chemistry , Dentin/drug effects , Dioxoles/chemistry , Benzodioxoles/chemistry , para-Aminobenzoates/chemistry , Polyethylene Glycols/chemistry , Polymethacrylic Acids/chemistry , Surface Properties , Tensile Strength , Time Factors , Materials Testing , Camphor/analogs & derivatives , Camphor/chemistry , Microscopy, Electron, Scanning , Reproducibility of Results , Dental Bonding/methods , Bisphenol A-Glycidyl Methacrylate/chemistry , Dentin/chemistry , Methacrylates/chemistryABSTRACT
Abstract This study evaluated the shear bond strength (SBS) of self-adhesive resin cements (SARCs) to dentin and their physical-chemical properties. Five commercial SARCs were evaluated [SmartCem®2 - DENTSPLY (SC2); BisCem® - Bisco (BC); SeT PP® − SDI (SeT); Relyx U100® - 3M ESPE (U100) and YCEM® SA - Yller (YCEM)]. The SARCs were evaluated for SBS to dentin (n = 10) after 24 h, 6 months, and 12 months. The dentin demineralization caused by acidic monomers was observed by SEM, and pH-neutralization of eluate was observed for 24 h. Degree of conversion (DC), rate of polymerization (Rp), flexural strength (FS), and elastic modulus (E) were evaluated. Immediate SBS of SC2, SET, U100, and YCEM were statistically higher than that of BC (p < 0.001). After 12 months, all SARCs showed reduced SBS values and U100 showed values similar to those of SET and YCEM, and higher than those of BC and SC2 (p = 0.001). Demineralization pattern of SARCs was similar. At 24h, all SARCs showed no differences in the pH-value, except BC and U100 (p < 0.001). YCEM showed the highest Rp. U100, YCEM, and SC2 showed statistically higher FS (p<0.001) and E (p < 0.001) when compared with SET and BC. U100 and YCEM showed the best long-term bonding irrespective of the storage period. A significant reduction in SBS was found for all groups after 12 months. SBS was not shown to be correlated with physical-chemical properties, and appeared to be material-dependent. The polymerization profile suggested that an increased time of light activation, longer than that recommended by manufacturers, would be necessary to optimize DC of SARCs.
Subject(s)
Composite Resins/chemistry , Resin Cements/chemistry , Dentin/drug effects , Light-Curing of Dental Adhesives/methods , Reference Values , Surface Properties/drug effects , Time Factors , Materials Testing , Microscopy, Electron, Scanning , Reproducibility of Results , Analysis of Variance , Pliability , Shear Strength , Dentin/chemistry , Phase Transition/drug effects , Elastic Modulus , PolymerizationABSTRACT
Abstract This study investigated the in vitro performance of the commercial bis-acryl composite resins Systemp C&B II (SYS, Ivoclar Vivadent), Protemp 4 (PT4, 3M ESPE), Structur 2C (ST2, Voco) and ProviPlast (PVP, Biodinamica). Characterization involved optical (color stability, translucency parameter, fluorescence), surface (roughness, morphology and elemental composition), physical-chemical (viscosity, polymerization kinetics) and mechanical analyses (Poisson ratio, biaxial flexural strength, flexural modulus). Most tests were carried out after 24 h, but optical and mechanical analyses were carried out after storage in water at 37 °C for 1, 15, and 30 days. Data were statistically analyzed (a=0.05). Most results were material dependent. SYS and PT4 showed stability in color and translucency over time. All materials had similar or higher fluorescence than human enamel. SC2 and PVP showed rougher surfaces than the other bis-acryl composites. Smaller filler particles were observed on the surface of PT4 and PVP compared with the coarser particles from ST2 and SYS. Viscosity readings indicated a thixotropic behavior for all tested materials. SYS had the lowest and PT4 the highest degree of C=C conversion after 10 min. In the polymerization kinetics, PT4 had the highest maximum polymerization rate and reached earlier the transition between polymerization autoacceleration and autodeceleration. PT4 and SYS had significantly higher flexural strength and modulus than ST2 and PVP for most storage times. Results for Poisson ratio varied between materials. Longer storage periods were generally associated with higher frequency of catastrophic failures in the flexural tests. In conclusion, the performance of bis-acryl composite resins varied largely among materials.
Resumo Este estudo investigou o desempenho in vitro de quatro resinas compostas bisacrílicas comerciais: Systemp C&B II (SYS, Ivoclar Vivadent), Protemp 4 (PT4, 3M ESPE), Structur 2C (ST2, Voco) e ProviPlast (PVP, Biodinamica). A caracterização envolveu análises ópticas (estabilidade de cor, parâmetro de translucidez, fluorescência), de superfície (rugosidade, morfologia e composição elementar), físico-químicas (viscosidade, cinética de polimerização) e mecânicas (razão de Poisson, resistência à flexão biaxial, módulo de elasticidade). A maioria dos testes foram realizados após 24 h, enquanto análises ópticas e mecânicas foram realizadas após armazenamento em água a 37 °C por 1, 15 e 30 dias. Os dados foram analisados estatisticamente (a=0,05). Grande parte dos resultados foi dependente do material. SYS e PT4 mostraram estabilidade de cor e translucidez ao longo do tempo. Todos os materiais apresentaram fluorescência similar ou maior que o esmalte humano. SC2 e PVP apresentaram superfícies mais rugosas que os outros materiais. Menores partículas de carga foram observadas na superfície de PT4 e PVP comparadas às partículas mais irregulares de ST2 e SYS. As leituras de viscosidade indicaram comportamento tixotrópico para todos os materiais testados. SYS teve a menor e PT4 o maior grau de conversão de C=C após 10 min. Na cinética de polimerização, PT4 teve a maior taxa máxima de polimerização e atingiu mais cedo a transição entre autoaceleração e autodesaceleração da polimerização. PT4 e SYS apresentaram resistência à flexão e módulo de elasticidade significativamente maiores que ST2 e PVP na maioria dos períodos de armazenamento. Resultados da razão de Poisson variaram entre os materiais. Períodos mais longos de armazenamento foram em geral associados a maior frequência de falhas catastróficas nos testes de flexão. Em conclusão, o desempenho das resinas compostas bisacrílicas variou amplamente entre os materiais.
Subject(s)
Humans , Composite Resins , Dental Restoration, Temporary , Dental Enamel/chemistry , Dental Stress Analysis , Fluorescence , Kinetics , Microscopy, Electron, Scanning , Poisson Distribution , Polymerization , Surface Properties , ViscosityABSTRACT
The aim of this study was to evaluate the addition of 2-[3-(2HBenzotriazol- 2-yl)-4-hydroxyphenyl]ethyl methacrylate (BTAM) to an experimental adhesive resin. An experimental base adhesive resin was formulated with BisGMA, TEGDMA and HEMA, to which BTAM was added at 1, 2.5 and 5%, in weight. One group with no addition was used as control. The experimental adhesives were evaluated for antibacterial potential (against Streptococcus mutans), degree of conversion with FTIR, softening in solvent and microRaman interface analyses. Data were analyzed by Kruskal-Wallis, paired t test and ANOVA and Tukey, considering a 5% level of significance. The results showed antibacterial activity of 5% BTAM against S. mutans (p<0.05), however, no difference was found among BTAM groups (p> 0.05). The results of degree of conversion and softening of solvent showed no statistical difference between BTAM and control groups (p>0.05). The addition of 5% BTAM showed higher antibacterial activity than the negative control, and copolymerization with comonomer blend of adhesive resin and BTAM was detected at the dentin/ adhesive interface.
O objetivo do presente estudo foi avaliar a adicao do 2-[3-(2HBenzotriazol- 2-yl)-4-hidroxifenil]etil metacrilato (BTAM) a um adesivo experimental. Uma resina adesiva base experimental foi formulada com BisGMA, TEGDMA e HEMA e a essa resina foi adicionado o BTAM nas concentracoes de 1, 2,5 e 5%, em peso, alem de um grupo controle sem adicao. Os adesivos experi - mentais foram avaliados quanto ao potencial antimicrobiano contra Streptococos mutans, grau de conversao com FTIR, degradacao em solvente e analise da interface com microespectroscopia Raman. Os dados foram analisados considerando um nivel de significancia de 5%. Os resultados obtidos no teste antimicrobiano contra S. mutans mostrou dife renca estatisticamente significativa do grupo com 5% de BTAM em relacao aos demais grupos e ao controle negativo (p<0,05). Os resultados de grau de conversao e degradacao em solvente dos grupos com BTAM nao apresentaram diferenca quando comparado ao grupo controle (p>0,05). Foi possivel observar a penetracao do BTAM na dentina. A adicao de BTAM na concentracao de 5% mostrou atividade antimicrobiana comparado ao controle negativo, alem de ter sido capaz de copolimerizar e penetrar na dentina.
Subject(s)
Humans , Methacrylates/chemistry , Adhesives , Dental Bonding , Dentin-Bonding Agents , Resin CementsABSTRACT
This study aimed to evaluate the factors associated with the decision to attend an academic post-graduation program by dental students. A cross-sectional study was conducted in 2012, last-year undergraduate students from Dental Schools of Southern Brazil. A closed questionnaire was applied including questions grouped in three different blocks: pre-graduate, undergraduate period and future perspectives. The outcome was the decision to pursuit an academic post-graduation degree. Associations were tested using chi-squared test and chi-squared test for linear trends when appropriate. Multivariate Poisson regression was also performed. The sample was composed by 671 students (response rate of 69.9%, n=467). In relation to future perspectives, 68% of the interviewed students intended to attend a post-graduation program, but only 17.5% would choose a program with academic and research post-graduation program (Master and PhD programs). In the final model, students from public universities (PR 2.08, 95%CI 1.41-3.08) and students that received scientific initiation scholarship (PR 1.93 95%CI 1.14-3.27) presented a twice greater prevalence to seek academic post-graduate programs. Students with higher family incomes showed a lower prevalence to seek these programs (PR 0.50, 95%IC 0.28-0.90). Scholarships seem to encourage undergraduate students to pursue stricto sensu post-graduation.
Este estudo objetivou avaliar os fatores associados com a decisão de estudantes de Odontologia em participar de um programa de pósgraduação acadêmica. Um estudo transversal foi conduzido em 2012, com estudantes do último ano do curso de Odontologia do Sul do Brasil. Foi aplicado um questionário fechado composto por três diferentes blocos: período prévio à graduação, período da graduação e perspectivas futuras. O desfecho deste trabalho foi definido como a decisão de buscar uma pós-graduação acadêmica. As associações foram testadas com o teste de Qui-quadrado e de Qui-quadrado de tendência linear, quando apropriado. Além disso, foi feita a regressão multivariada de Poisson. A amostra foi composta por 671 estudantes (taxa de resposta de 69,9%, n=467). Em relação às perspectivas futuras, 68% dos estudantes entrevistados pretendem ingressar em um curso de pós-graduação, mas somente 17,5% escolheriam um programa com pós-graduação acadêmica e pesquisa (Programas de Mestrado e Doutorado). No modelo final, estudantes de universidades públicas (RP 2,08, 95% CI 1,41-3,08) e estudantes que receberam bolsa de iniciação científica (RP 1,93 95% CI 1,14-3,27) apresentaram prevalência duas vezes maior na busca de pós-graduação acadêmica. Estudantes de famílias com renda alta mostraram menor prevalência na busca destes cursos (RP 0,50, 95%IC 0,28-0,90). Desta forma, bolsas parecem incentivar os alunos de graduação na busca por pós-graduação stricto sensu.