Analysis of the marginal adaptation of different crowns fabricated with computer-aided technology using an intraoral digital scanner

Aim: The aim of this study was to evaluate the marginal adaptation of ceramic and composite resin crowns fabricated with computer-aided design and computer-aided manufacturing (CAD/CAM) technology using an intraoral digital scanner. Methods: A human mandibular right second molar was prepared for a ceramic crown. The impressions were made using intraoral scanning device and crowns were milled. Tem crowns were fabricated for each group (n=10): GF ­ Feldspathic Ceramic (Cerec Blocs, Sirona), GL - Lithium Disilicate Ceramic (IPS e.max CAD, Ivoclar), GG - composite resin (Grandio Blocs, VOCO) and GB - composite resin (Brava Block, FGM). The marginal gap was measured for each specimen at 4 points under magnification with a stereomicroscope. All data were statistically analyzed using one-way ANOVA followed by the Tukey's test (α=.05). Results: The lowest marginal discrepancy value was observed in GB (60.95 ± 13.64 µm), which was statistically different from the GL (84.22 ± 20.86 µm). However, there was no statistically significant difference between these groups when compared with the other groups, GF (73.26 ±8.19 µm) and GG (68.42 ± 11.31 µm). Conclusion: It can be concluded that the composite resin presented the lowest variance compared to the lithium disilicate glass ceramic, although the marginal gap of all materials tested was within the acceptable clinical limit (120 µm)

Resistência à flexão de duas resinas compostas diretas após diferentes métodos de polimerização / Flexural strength of two direct composite resins after different polymerization methods

Objetivo: avaliar a influência de diferentes modos de polimerização sobre a resistência à flexão de três pontos de duas resinas compostas. Métodos: foram confeccionadas 88 amostras, sendo divididas em dois grupos, conforme a resina composta utilizada: Filtek Z350 XT e Forma. Os grupos foram subdivididos, de acordo com diferentes modos de polimerização, em: G1- Z350 por 20s a 1.000 mw/cm²; G2- Forma por 20s a 1.000 mw/cm²; G3- Z350 por 20s a 1.000 mw/cm² e micro-ondas por 3 minutos em 450w; G4- Forma por 20s a 1.000 mw/cm² e micro-ondas por 3 minutos em 450w; G5- Z350 por 2 vezes de 3s a 3.200 mw/cm²; G6- Forma por 2 vezes de 3s a 3.200 mw/cm²; G7- Z350 por 2 vezes de 3s a 3.200 mw/cm² e micro-ondas por 3 minutos em 450w; G8- Forma por 2 vezes de 3s a 3.200 mw/cm² e micro-ondas por 3 minutos em 450w. As amostras foram submetidas ao teste de resistência à flexão de 3 pontos, sob taxa de carregamento de 50 N/min, até a falha completa. Os dados foram analisados estatisticamente por análise de variância com dois fatores (two-way ANOVA) e teste de Tukey. Resultados: não houve diferenças estatísticas entre as resinas compostas e os modos de polimerização utilizados. Conclusão: de acordo com os resultados do estudo, e dentre suas limitações, os modos de polimerização não influenciaram a resistência à flexão, independentemente da resina composta testada. (AU)

Objective: to evaluate the influence of different polymerization modes on the three-point flexural strength of two composite resins. Methods: 88 samples were produced and divided into two groups according to the composite resin used: Filtek Z350 XT and Forma. The groups were subdivided according to different polymerization modes into: G1- Z350 for 20 s at 1000 mw/cm²; G2- Forma for 20 s at 1000 mw/cm²; G3- Z350 for 20 s at 1000 mw/cm² and microwave for 3 min at 450w; G4- Forma for 20 s at 1000 mw/cm² and microwave for 3 min at 450w; G5- Z350 2x for 3 s at 3200 mw/cm²; G6- Forma 2x for 3 s at 3200 mw/cm²; G7- Z350 2x for 3 s at 3200 mw/cm² and microwave for 3 min at 450w; and G8- Forma 2x for 3 s at 3200 mw/cm² and microwave for 3 min at 450w. The samples were subjected to the three-point flexural strength test under a 50 N/min loading rate until complete failure. The data were statistically analyzed using two-way analysis of variance (two-way ANOVA) and Tukey's test. Results: there were no statistical differences between the composite resins and the polymerization modes used. Conclusion: according to the study results and within its limitations, the polymerization modes did not affect flexural strength, regardless of the composite resin tested. (AU)

Efeito do peróxido de hidrogênio na permeabilidade dental / Effects of hydrogen peroxide on dental permeability

Resumo Objetivo: Este trabalho avaliou o efeito de quatro agentes clareadores na permeabilidade dental. Material e Métodos: Dentes bovinos foram divididos em quatro grupos (n = 10). A permeabilidade inicial dos dentes foi determinada previamente ao clareamento, utilizando equipamento de permeabilidade. Em seguida, foram aplicados os géis clareadores e a permeabilidade novamente mensurada. Os resultados foram expressos em porcentagem de aumento da permeabilidade e os dados submetidos à análise estatística (ANOVA e teste Tukey). Resultados: O Whiteness HP Maxx resultou em maior aumento de permeabilidade (145,7±76,3), quando comparado com Whiteness HP Blue (57,5±36,1) e Pola Office Plus (72,7±19,5). Esses produtos não apresentaram diferença estatística com relação ao Opalescence Boost PF (101,4±46,3). Conclusão: Todos os agentes clareadores testados aumentaram a permeabilidade. A intensidade desse aumento foi dependente do produto utilizado.

Objective: This study evaluated the effect of four bleaching agents on the dental permeability. Material and Methods: Bovine teeth were divided into four groups (n=10), and the initial dental permeability was measured before the bleaching treatments, using a dental hydraulic permeability device. Afterwards, teeth were bleached with whitening products, and the final permeability was recorded. The results were expressed in percentage of increasing permeability (%) and data were submitted to ANOVA and Tukey's test. Results: Whiteness HP Maxx produced higher dental permeability (145.7±76.3) than Whiteness HP Blue (57.5±36.1) and Pola Office Plus (72.7±19.5), which did not differ from Opalescence Boost PF (101.4±46.3). Conclusion: All bleaching agents increased the dental permeability. The increasing intensity was product-dependent.

Indirect Restoration Thickness and Time after Light-Activation Effects on Degree of Conversion of Resin Cement

This study evaluated the effects of indirect restorative materials, curing conditions and time on the degree of conversion (DC) of a dual-cured resin cement using infrared spectroscopy. The resin cement (RelyX Unicem 2, 3M ESPE) was applied to the diamond surface of a horizontal attenuated-total-reflectance unit and activated using one of following conditions: self-cure, direct light exposure, light exposure through indirect restorative materials (resin nano-ceramic: Lava Ultimate, 3M ESPE or feldspathic ceramic: Vita Blocks Mark II, Vita Zahnfabrik). Four thicknesses (0.5, 1.0, 1.5 or 2.0 mm) of each indirect material were analyzed, and the light-activation was performed using a blue LED light. Data (n=5) were analyzed by three-way ANOVA, Tukey's post hoc and Dunnett's tests (α=5%). No significant differences in DC were observed between indirect materials of similar thickness. All groups exhibited higher DC after 10 min than after 5 min. At both times points, the self-cure group exhibited significantly lower DC than all the light exposure groups. Only when the overlying indirect restoration had a thickness of 2 mm did DC decrease significantly. The presence of a thick, indirect restoration can decrease the DC of resin cement. DC after 10 min was higher than after 5 min. The self-cure mode yielded lower DC than the light-activating one.

Este estudo avaliou os efeitos do tipo de material restaurador indireto, da condição de ativação e do tempo no grau de conversão de um cimento resinoso de dupla ativação, utilizando espectroscopia de luz infravermelha. O cemento resinoso (RelyX Unicem 2, 3M ESPE) foi aplicado à superfície do diamante da unidade de reflectância atenuada e ativado segundo as seguintes condições: ativação química, exposição direta da luz e aplicação da luz através de dois materiais protéticos: resina nano-cerâmica (Lava Ultimate, 3M ESPE) ou cerâmica feldspática (Vita Blocks Mark II, Vita Zahnfabrik). Quatro espessuras de cada um desses materiais (0,5; 1,0; 1,5 e 2,0 mm) foram analisadas e a ativação realizada com luz LED. Os dados (n=5) foram analisados pela ANOVA três fatores, testes de Tukey e Dunnett (5%). Nenhuma diferença do grau de conversão foi observada entre os materiais. Todos os grupos mostraram maior grau de conversão após 10 min que após 5 min. Em ambos os tempos, o grupo ativado quimicamente teve menor grau de conversão que todos os grupos fotoativados. O grau de conversão foi reduzido somente quando foi utilizada a peça protética de 2 mm. Espessas peças protéticas podem reduzir o grau de conversão do cemento resinoso. A grau de conversão após 10 min é maior que após 5 min da cimentação. A ativação química produz menor grau de conversão que a fotoativação.

Avaliação da resistência de união adesivo-dentina - Efeito do armazenamento em saliva artificial / Bond strength evaluation of adhesive-dentin - Effect of artificial saliva storage

Introdução - Os sistemas adesivos têm evoluído e a durabilidade da união resina-dentina é um assunto importante na Odontologia Restauradora, uma vez que está diretamente relacionada com a longevidade dos procedimentos restauradores. Este estudo avaliou o efeito do tempo de armazenamento em saliva artificial na resistência de união de 4 adesivos à dentina. Material e Métodos - Vinte terceiros molares foram utilizados e divididos em 4 grupos (n=5), que corresponderam aos adesivos testados: Adper Easy Bond (EB), AdperSE Plus (SP), Adper Single Bond 2 (SB) e Clearfil SE Bond (CS). Os adesivos foram aplicados na dentina oclusal planificada e em seguida, os dentes foram restaurados com incrementos de 2 mm de resina composta. Após armazenamento em água destilada por 24 horas, os dentes restaurados foram seccionados seguindo a metodologia de microtração. Metade dos espécimes obtidos de cada dente foi armazenada em saliva artificial a 37°C por 6 meses (6ME) e a outra metade (24H) submetida ao teste de microtração. Os dados foram analisados pela ANOVA (2 fatores) e teste de Tukey (p<0,05). Resultados - Os adesivos produziram similar resistência de união à dentina nos dois tempos avaliados (p=0,7860). A resistência de união de união dos adesivos não apresentou diferença significativa entre os tempos avaliados (p=0,8454). As médias de resistência de união (DP) para os adesivos foram (MPa): EB(24H): 57,8(17,4), EB(6ME): 57,7(18,5), SP(24H): 57,9(15,5), SP(6ME): 55,9(9,6), SB(24H): 48,9(8,1), SB(6ME): 49,7(7,9), CS(24H): 60,1(21,0) e CS(6ME): 59,0(9,5). Conclusão - A resistência da união adesivo-dentina não foi afetada pelo tempo do armazenamento.

Introduction – The adhesive systems have improved and the resin-dentin bond durability is an important subject within Restorative Dentistry, since it is related to longevity of composite restorations. This study evaluated the effect of artificial saliva storage on bond strength of 4 adhesives to dentin. Material and Methods - Twenty third molars were used in this study. They were divided into 4 groups (n=5), which corresponded to adhesives tested: Adper Easy Bond (EB), Adper SE Plus (SP), Adper Single Bond 2 (SB) and Clearfil SE Bond (CS). Bonding agents were applied to flat oclusal dentin surface and the teethwere incrementally restored with composite resin. After 24 hours of water storage, the restored teeth were sectioned according to the micro-tensile bond methodology. The half of bonded beam specimens were stored in artificial saliva at 37 oC for 6 months (6ME) andthe other half (24H) was tested in tension. Data were analyzed by two-way ANOVA and Tukey test (p<0.05). Results - The results suggested that the adhesives present similar bond strength mean values to dentin in both evaluation times. (p=0.7860). The bond strengthof adhesive systems was not different between the evaluation times (p=0.8454). The bond strength means (DP) for the adhesives were (MPa): EB(24H): 57.8(17.4), EB(6ME): 57.7(18.5), SP(24H): 57.9(15.5), SP(6ME): 55.9(9.6), SB(24H): 48.9(8.1), SB(6ME): 49.7(7.9), CS(24H): 60.1(21.0) and CS(6ME): 59.0(9.5). Conclusion - The resin-dentinbond strength of the adhesives tested was not affect by storage.

Effect of adhesive system and application strategy on reduction of dentin permeability

This study evaluated the effect of adhesive systems and application strategies on dentin hydraulic conductance (HC). The buccal enamel was removed from bovine incisors to simulate laminate cavity preparations. After removing the roots and the coronal pulp, the buccal dentin was treated with EDTA solution (0.5 M) for 5 minutes, rinsed, ultrasonicated for 12 minutes and connected to a permeability device. HC of the specimens was measured at 10 psi (n = 5). Permeability was measured before and after bonding procedures using G-Bond (GB), Clearfil Tri-S Bond (CTS), Hybrid Coat (HY), Bond Force (BF), Adper Easy Bond (AEB) Silorane (SI), Clearfil SE Bond (CSE) and Adper Scotchbond Multi-Purpose (SMP) adhesives systems, which were applied following three strategies: 1) according to the manufacturers' instructions; 2) two coats of all-in-one self-etching adhesives (GB, CTS, HY, BF, AEB) or priming step plus two coats of bonding resin for the other systems (SI, CSE and SMP); and 3) a thin layer of a flowable composite applied over one coat of all-in-one self-etching adhesives or primed surface for SI, CSE and SMP adhesives. No significant difference was observed among the application modes concerning their ability to reduce HC. None of the adhesives showed complete sealing (100%) of the bovine tooth dentin. SI exhibited lower HC than SMP, however, they were not significantly different from the other systems. The results suggest that all systems tested result in an HC reduction of more than 90%. The wet bonding technique seemed to be more sensitive for dentin sealing.