Effect of combining photoinitiators on cure efficiency of dental resin-based composites

Abstract Camphorquinone is the most conventionally used photoinitiator in Dentistry. Although different alternative photoinitiators have been proposed, no photoinitiator was capable of completely substituting camphorquinone. The combination of photoinitiators has been considered the best alternative. Objectives: To evaluate the effect of combining Norrish type I and II photoinitiators on the cure efficiency of dental resin-based composites. Methodology: Experimental composites were produced containing different photoinitiator systems: Norrish type I-only, mono-alkyl phosphine oxide (TPO); Norrish type II-only, camphorquinone (CQ); or its combination, CQ and TPO, in a 1: 1 molar ratio. UV-vis absorption spectrophotometry was performed to assess the consumption of each photoinitiator after curing (n=3). A multi-wave LED (Bluephase® G2, Ivoclar Vivadent) was pre-characterized and used with a radiant exposure of 24 J/cm2. The degree of conversion was evaluated by Raman spectrometry, and the elution of the monomers by nuclear magnetic resonance analysis (n=3). Data were analyzed using ANOVA and Tukey's test (α=0.05; β=0.2). Results: The combination of CQ and TPO increased the consumption of the photoinitiator system compared to CQ-only (p=0.001), but presented similar consumption compared to TPO-only (p=0.52). There was no significant difference in the degree of conversion between the composites regardless of the photoinitiator system (p=0.81). However, the elution of the monomers was reduced when both photoinitiators were combined. TPO-based material presented the highest elution of monomers. Conclusions: The combination of the photoinitiator systems seems to be beneficial for the cure efficiency of dental resin-based composites.

Effect of alternative solvent evaporation techniques on mechanical properties of primer-adhesive mixtures / Efeito de técnicas alternativas utilizando evaporação de solvente nas propriedades mecânicas da mistura primer-adesivo

ABSTRACT This study evaluated the influence of the mode and time of solvent evaporation on the tensile strength (TS), flexural strength (FS) and elastic modulus (EM) of two adhesive systems: Scotchbond Multipurpose (SBMP) and Clearfil SE (CSEB). For this purpose, rectangular samples (2x1x7 mm) were prepared with 10 μL of primer and the solvents were evaporated with air spray at (23±1) ºC, (40±1) ºC and negative control (without spray). For each temperature, the times of 5, 20, 30, and 60 seconds were investigated. The statistical results showed that evaporation at 40±1ºC resulted in better EM for the two adhesives tested and all the evaporation times evaluated. However, there were no significant differences between the times and modes of evaporation for TS. The results of this study indicate that evaporation at a temperature of (40±1) °C could improve the elastic modulus of both adhesives tested, regardless of the evaporating time.

RESUMO Este estudo avaliou a influência do modo e do tempo de evaporação do solvente na resistência à tração (RT), resistência à flexão (RF) e módulo de elasticidade (MR) de dois sistemas adesivos: Scotchbond Multipurpose (SBMP) e Clearfil SE (CSEB). Para isso, amostras retangulares (2x1x7 mm) foram preparadas com 10 μL de primer e os solventes foram evaporados com aerossol a (23±1) ºC, (40±1) ºC e controle negativo (sem aerossol). Para cada temperatura, foram avaliados os tempos de 5, 20, 30 e 60 segundos. Os resultados estatísticos mostraram que a evaporação a (40±1) ºC resultou em melhor MR para os dois adesivos testados e todos os tempos de evaporação avaliados. No entanto, não houve diferenças significativas entre os tempos e modos de evaporação na RT. Os resultados deste estudo indicam que a evaporação a uma temperatura de (40±1) °C poderia melhorar o módulo de elasticidade de ambos os adesivos testados, independentemente do tempo de evaporação.

Evaluation of the physical and antifungal effects of chlorhexidine diacetate incorporated into polymethyl methacrylate

Abstract This study aimed to evaluate the physical properties and antifungal activities of polymethyl methacrylate (PMMA) acrylic resins after the incorporation of chlorhexidine diacetate salt (CDA). Methodology: First, acrylic resin specimens were fabricated with Vipi Cor® and DuraLay® resins with and without the incorporation of 0.5%, 1.0% or 2.0% CDA. The residual monomer and CDA release were measured at intervals ranging from 2 hours to 28 days using ultraviolet spectrometry combined with high-performance liquid chromatography. The antifungal activity against C. albicans was evaluated with the agar diffusion method. Fourier transform infrared spectroscopy was used to analyze the degree of resin conversion. Finally, the water sorption values of the resins were also measured. Results: The incorporated CDA concentration significantly changed the rate of CDA release (p<0.0001); however, the brand of the material appeared to have no significant influence on drug release. Subsequently, the inhibition zones were compared between the tested groups and within the same brand, and only the comparisons between the CDA 2% and CDA 1% groups and between the CDA 1% and CDA 0.5% groups failed to yield significant differences. Regarding the degrees of conversion, the differences were not significant and were lower only in the CDA 2% groups. Water sorption was significantly increased at the 1.0% and 2.0% concentrations. Conclusions: We concluded that the incorporation of CDA into PMMA-based resins enabled the inhibition of C. albicans growth rate, did not alter the degrees of conversion of the tested resins and did not change the release of residual monomers.

Aesthetic solution for ceramic restoration on cast metal core

Introduction: In order to satisfy the aesthetic desires of the population, by masking the restorations was the search for the evolution of restorative materials enabling the introduction of metal-free materials. But previous studies that have been made with metal structures often cannot be removed and therefore require devices that can be masked, because there is no desire for a total passage of light avoiding dim reflection of these funds. For these situations, you must opt for a ceramic system to provide a degree of opacity, without losing its characteristics of light transmission, reflectance and saturation. Case report: In case the patient had clinical a metal ceramic crown on the molten core element 21, it was confirmed radiographically the core could not be removed because it would fracture risk to the tooth. We chose to use an opaquer ceramic framework to prevent the passage of light over dark metal. The material of choice was zirconia ceramic by high flexural strength, allowing it to function as a framework for crowns. Conclusion: With the correct application of ceramic coverage on Caquetá noted that it is possible to mask the gray color of the metal through the knowledge of the optical material, the correct use of these properties, opacity and translucidus, and a close contact between dentists and prosthetic.

Introdução: A fim de satisfazer os anseios estéticos, da população, por mascarar as restaurações houve a busca pela evolução dos materiais restauradores possibilitando a introdução de materiais livres de metais. Porém trabalhos prévios que foram confeccionados com estruturas metálicas muitas vezes não podem ser removidos e, portanto, necessitam de artifícios para que possam ser mascarados, pois não há o desejo de uma total passagem de luz evitando a reflexão desses fundos escurecidos. Para estas situações, é necessário optar por um sistema cerâmico que apresente um grau de opacidade, sem perda de suas características de translucidez, refletância e saturação. Relato do caso: A paciente possuía uma coroa metalo-cerâmica sobre núcleo fundido no elemento 21, constatou-se radiograficamente que o núcleo não podia ser retirado, pois traria risco de fratura ao dente. Optou-se por utilizar uma cerâmica mais opaca de arcabouço para evitar a passagem de luz sobre o metal escurecido. O material de escolha foi à cerâmica de zircônia por apresentar alta resistência à flexão, permitindo que funcione como arcabouço para coroas unitárias. Conclusão: Com a correta aplicação de cerâmicas de cobertura sobre o casquete observou- se que é possível mascarar a cor acinzentada do metal através dos conhecimentos ópticos do material, a correta utilização dessas propriedades, opacidade e translucides, e um estreito contato entre dentista e protético.

Influência da camada híbrida na resistência à microtração de sistemas adesivos após armazenamento / Hibrid layer influence in bond systems microtensile test after storage

O objetivo deste estudo foi avaliar a resistência à microtração de sistemas adesivos em função da presença ou não da camada de colágeno e do tempo de armazenamento. Para tanto foram utilizados 24 terceiros molares restaurados utilizando-se diferentes sistemas adesivos, com ou sem tratamento prévio com NaOCl, e armazenados por 24 horas e 12 meses. Os valores de resistência foram submetidos à análise estatística. O tratamento prévio com NaOCl não foi significativo em 24 horas. Entretanto, este tratamento manteve resultados satisfatórios de adesão após 12 meses para todos os sistemas adesivos, com exceção apenas do Prime & Bond NT.

The aim of the present study was to evaluate the microtensile bond strength of different bond systems due to presence or absence of the collagen layer and storage time. Therefore, 24 third molars were restored using different bond systems, with or without pretreatment with NaOCl, and stored for 24 hours and 12 months. The microtensile strength values were subjected to statistical analysis. The pretreatment with NaOCl was not significant in 24 hours. However, this pretreatment remained satisfactory bond results after 12 months for all bond systems, except for Prime & Bond NT.

Trauma dentário: tratamento multidisciplinar: Relato de caso / Dental trauma: Multidisciplinary treatment: Case report

O traumatismo dentário afeta, principalmente, crianças na faixa etária entre 2 a 10 anos, sendo mais afetados os incisivos centrais superiores, devido ao posicionamento vulnerável na arcada. De acordo com a necessidade estética e a fragilidade do estágio de desenvolvimento do dente, o tratamento deve ser acompanhado de diferentes formas. Esse relato clínico tem po objetivo apresentar o acompanhamento multidisciplinar de acordo com a evolução do caso clínico. A determinação de cada procedimento se baseou na manutenção da saúde dos tecidos periodontais e na reabilitação dentária e, por conclusão, que o planejamento do tratamento multidisciplinar é fundamental para a otimização dos resultados obtidos na realização dos procedimentos que visam o restabelecimento estético-biológico satisfatório do elemento dentário afetado pelo trauma.

Dental trauma mainly affects children, between 2 - 10 years old. Due to the vulnerable positioning, upper central incisors are the most affected. According to the esthetic needing and the fragile stage of tooth development, the treatment must be accompanied in different ways. This clinical report aims to present the multidisciplinary follow-up of a clinical case evolution. Each procedure determination was based on maintaining periodontal tissue health and dental rehabilitation and,by conclusion, the multidisciplinary treatment is essential to meet requirements during the case development, ensuring satisfactory esthetic and biological results in trauma affected teeth affected.