Effect of adding arginine at different concentrations to experimental orthodontic resins: an in vitro study.

The aim of this study was to assess the effect of adding arginine at different concentrations to commercial and experimental orthodontic resins on shear bond strength (SBS), as well as on the antimicrobial activity of arginine against S. mutans. Metal brackets were bonded onto the surface of 120 bovine incisors using Transbond, OrthoCem, and an experimental resin (ER), adding 0, 2.5, 5, and 7 wt.% of arginine. The SBS test was performed in deionized water at 37 ºC for 24 h, at 0.5 mm/min. SBS test results were subjected to two-way ANOVA and Tukey's test (α = 0.05). CFU/mL data (antimicrobial assessment) were assessed by Kruskal-Wallis and Dunn's tests (α = 0.05). No statistical difference between the resins was observed in untreated groups (p > 0.05). The addition of arginine at 2.5% (27.7 MPa) and 5% (29.0 MPa) increased the SBS of Transbond when compared (p < 0.05) to OrthoCem (18.5 and 15.6 MPa, respectively) and ER (16.3 and 18.1 MPa, respectively). Arginine at 7% improved the SBS of Transbond (24.1 MPa) and ER (21.0 MPa), which was statistically higher (p < 0.05) than OrthoCem (12.6 MPa). OrthoCem did not show a statistically significant difference at the three concentrations of arginine (p > 0.05). The addition of arginine to resins reduced the count of S. mutans (p < 0.05). As for ER, all concentrations of arginine significantly decreased CFU/mL (p < 0.05). Among commercial resins, only 7% of arginine significantly reduced CFU/mL. The addition of arginine did not interfere with the bond strength and demonstrated antibacterial activity against S. mutans.

Effect of hydrofluoric acid concentration and aging on the bond strength ceramics to a resin cement.

This study evaluated the influence of hydrofluoric acid (HF) concentration and thermal cycling on the microshear bond strength (µSBS) of a resin luting agent to IPS e.max® CAD and Rosetta® SM. Ceramic specimens (12.0 x 14.0 x 1.5mm) were randomized into 8 groups (n=10) according to HF concentration, commercial brand, and aging. Immediately after polishing, and etching, all specimens were silanized and a layer of adhesive was applied. A PVS mold of 3 mm thickness and 10mm diameter with (four) 1.0mm holes was fabricated, placed on each specimen, and then filled with a resin luting agent. Half of the specimens were subjected to the µSBS test using an Instron at a speed of 1.0 mm/min, following a 24-hour storage in deionized water at 37ºC. The remaining specimens were subjected to thermal cycling (5ºC-55ºC, 30 seconds per bath) and µSBS. The data were evaluated utilizing a three-way ANOVA and Tukey's post-hoc test (α=0.05). Significant differences were found for HF concentration and aging (p<0.0001). No significant difference in µSBS was found for commercial brands (p=0.085). The interaction between brand and HF concentration (p=0.358), brand and aging (p=0.135), and HF concentration and aging (p=0.138) were not statistically significant. The triple interaction among these factors was not statistically significant (p=0.610). In conclusion, the bond strength is affected by the HF concentration. No statistical difference was observed between the two ceramics. Thermal cycling significantly reduced µSBS.

Effect of hydrofluoric acid concentration and aging on the bond strength ceramics to a resin cement

Abstract This study evaluated the influence of hydrofluoric acid (HF) concentration and thermal cycling on the microshear bond strength (µSBS) of a resin luting agent to IPS e.max® CAD and Rosetta® SM. Ceramic specimens (12.0 x 14.0 x 1.5mm) were randomized into 8 groups (n=10) according to HF concentration, commercial brand, and aging. Immediately after polishing, and etching, all specimens were silanized and a layer of adhesive was applied. A PVS mold of 3 mm thickness and 10mm diameter with (four) 1.0mm holes was fabricated, placed on each specimen, and then filled with a resin luting agent. Half of the specimens were subjected to the µSBS test using an Instron at a speed of 1.0 mm/min, following a 24-hour storage in deionized water at 37ºC. The remaining specimens were subjected to thermal cycling (5ºC-55ºC, 30 seconds per bath) and µSBS. The data were evaluated utilizing a three-way ANOVA and Tukey's post-hoc test (α=0.05). Significant differences were found for HF concentration and aging (p<0.0001). No significant difference in µSBS was found for commercial brands (p=0.085). The interaction between brand and HF concentration (p=0.358), brand and aging (p=0.135), and HF concentration and aging (p=0.138) were not statistically significant. The triple interaction among these factors was not statistically significant (p=0.610). In conclusion, the bond strength is affected by the HF concentration. No statistical difference was observed between the two ceramics. Thermal cycling significantly reduced µSBS.

Resumo Este estudo avaliou a influência da concentração do ácido fluorídrico (AF) e da ciclagem térmica na resistência de união ao microcisalhamento (RUµC) de um cimento resinoso para IPS e.max® CAD e Rosetta® SM. Espécimes cerâmicos (12,0 x 14,0 x 1,5mm) foram divididos em 8 grupos (n=10) de acordo com concentração do HF, marca comercial e envelhecimento. Imediatamente após o polimento e condicionamento ácido, todos os espécimes foram silanizados e uma camada de adesivo foi aplicada. Um molde PVS de 3 mm de espessura e 10 mm de diâmetro com (quatro) orifícios de 1,0 mm foi confeccionado, colocado em cada espécime e preenchido com o cimento resinoso. Metade dos espécimes foi submetida ao teste RUµC na Instron a velocidade de 1,0 mm/min, após 24 horas de armazenamento em água deionizada a 37ºC. Os espécimes restantes foram submetidos a ciclagem térmica (5ºC-55ºC, 30 segundos por banho) e a RUµC. Os dados foram avaliados por ANOVA de três fatores e ao teste post-hoc de Tukey (α=0,05). Diferenças significativas foram encontradas para concentração de HF e envelhecimento (p<0,0001). Nenhuma diferença significativa na RUµC foi encontrada para cada marca comercial (p=0,085). A interação entre marca comercial e a concentração do HF (p=0,358), marca comercial e envelhecimento (p=0,135) e concentração do HF e envelhecimento (p=0,138) não foram estatisticamente significativas. A tripla interação entre esses fatores não foi estatisticamente significativa (p=0,610). Concluindo, a resistência de união é afetada pela concentração de HF. Não foi observada diferença estatística entre as duas cerâmicas. A ciclagem térmica reduziu significativamente a resistência de união ao microcisalhamento.

Comparison of the physico-chemical impact of chlorhexidine and silver nanoparticles on orthodontic appliances made with laser and silver solder: An in vitro study.

OBJECTIVE: The aim of this study was to evaluate the physical-chemical changes in orthodontic devices made with laser and silver solder after immersion in different antiseptic solutions. METHODS: Wire/band assemblies were fabricated using different types of solders (silver and laser). The devices were immersed in different antimicrobial solutions (chlorhexidine - CHX 0.12% and Silver nanoparticles - NAg 0.12% and 0.18%). Non-immersion in solution and immersion in artificial saliva were used as initial and negative control, respectively (n=12). Surface morphological analysis was performed using Scanning Electron Microscopy (SEM). The quantitative analysis of the chemical elements present after the immersions in the solutions was analysed by Energy Dispersive X-ray Spectroscopy (EDS). The data were subjected to the Kruskal-Wallis test followed by Bonferroni, with a significance level of 5%. RESULTS: Greater amounts of copper, silver and zinc were released from silver soldering, on the other hand, iron, nickel, and chromium ions were the most prevalent metal ions in laser soldering. Regarding mouthwashes, the lowest amounts of metal ions were released in CHX, and the highest amounts of ions were released in the 0.12% NAg and 0.18% NAg solutions. CONCLUSIONS: Laser welding seems to be less susceptible to corrosion. The different antiseptic solutions did not contribute to an increase in ion release.

CHX Stabilizes the Resin/demineralized Dentin Interface.

The aim of this study was to evaluate the effect of 2% chlorhexidine digluconate (CHX) on microtensile bond strength (µTBS) between an adhesive system and under 3 dentin conditions. For that, this study evaluated the adhesive interface at initial, after 6 months and 1 year of storage. Forty-eight human third molars were prepared and randomly divided into 3 groups, according to dentin substrates: sound dentin (Sd), caries-infected dentin (Ci) and caries-affected dentin (Ca). The groups were subdivided into two according to the dentin pre-treatment: application of 2% CHX or without pre-treatment (control). The dentin surfaces were etched with 35% phosphoric acid gel and bonded with Adper Single Bond 2 (3M ESPE) adhesive system according to manufacturer's instructions. Subsequently, the specimens were stored in deionized water at 37°C for 24h, 6 months and 1 year. Two additional teeth were used to analyze the bonding interfaces by SEM. Data was submitted to three-way ANOVA in a split plot design and Tukey's test (α = 0.05). The results showed that Ci decreased µTBS values when compared to Ca and Sd, regardless storages time or treatment. Stored samples for 6 months and 1 year decreased the µTBS for the control group, but no difference was found between storages time for the CHX group. As a conclusion, the 2% CHX application after etching showed improved dentin bond strength in the storage time, regardless of the substrates evaluated.

CHX stabilizes the resin/demineralized dentin interface

Abstract The aim of this study was to evaluate the effect of 2% chlorhexidine digluconate (CHX) on microtensile bond strength (µTBS) between an adhesive system and under 3 dentin conditions. For that, this study evaluated the adhesive interface at initial, after 6 months and 1 year of storage. Forty-eight human third molars were prepared and randomly divided into 3 groups, according to dentin substrates: sound dentin (Sd), caries-infected dentin (Ci) and caries-affected dentin (Ca). The groups were subdivided into two according to the dentin pre-treatment: application of 2% CHX or without pre-treatment (control). The dentin surfaces were etched with 35% phosphoric acid gel and bonded with Adper Single Bond 2 (3M ESPE) adhesive system according to manufacturer's instructions. Subsequently, the specimens were stored in deionized water at 37°C for 24h, 6 months and 1 year. Two additional teeth were used to analyze the bonding interfaces by SEM. Data was submitted to three-way ANOVA in a split plot design and Tukey's test (α = 0.05). The results showed that Ci decreased µTBS values when compared to Ca and Sd, regardless storages time or treatment. Stored samples for 6 months and 1 year decreased the µTBS for the control group, but no difference was found between storages time for the CHX group. As a conclusion, the 2% CHX application after etching showed improved dentin bond strength in the storage time, regardless of the substrates evaluated.

Resumo O objetivo deste estudo foi avaliar o efeito do digluconato de clorexidina 2% (CHX) na resistência de união à microtração (µTBS) entre um sistema adesivo e sob 3 condições de dentina. Para tanto, este estudo avaliou a interface adesiva no início, após 6 meses e 1 ano de armazenamento. Quarenta e oito terceiros molares humanos foram preparados e divididos aleatoriamente em 3 grupos, de acordo com os substratos dentinários: dentina hígida (Dh), dentina infectada por cárie (Di) e dentina afetada por cárie (Da). Os grupos foram subdivididos em dois de acordo com o pré-tratamento: aplicação de CHX 2% ou sem pré-tratamento (controle). As superfícies da dentina foram condicionadas com gel de ácido fosfórico a 35%, em seguida, utilizou-se o sistema adesivo Adper Single Bond 2 (3M ESPE) de acordo com as instruções do fabricante. Posteriormente, os corpos-de-prova foram armazenados em água deionizada a 37°C por 24h, 6 meses e 1 ano. Dois dentes adicionais foram usados ​​para analisar as interfaces de união no MEV. Os dados foram submetidos a ANOVA três fatores em esquema de parcela subdividida e ao teste de Tukey (α = 0,05). Os resultados mostram que a Di diminuiu os valores de µTBS quando comparado as Da e Dh, independente do tempo de armazenamento ou tratamento. Amostras armazenadas por 6 meses e 1 ano diminuíram a µTBS para o grupo de controle, mas nenhuma diferença foi encontrada entre o tempo de armazenamento para o grupo CHX. A aplicação de CHX 2% após o condicionamento apresentou melhora na resistência de união à dentina no tempo de armazenamento, independente dos substratos avaliados.

Evaluation of the influence of light-curing units on the degree of conversion in depth of a bulk-fill resin.

BACKGROUND: It is known that bulk-fill have been widely studied and used by dentists in the clinic. However, the use of light-curing units that do not have the ability to adequately light-cure these materials at the appropriate depth can affect their clinical performance. The aim of this study was evaluating the influence of 5 different light curing units (LCUs) on the degree of conversion (DC) of a bulk-fill resin at depths of 0 to 4 mm and determined the effect of using 20s exposure and 40s. MATERIAL AND METHODS: Cylinders of composite were made in a stainless steel matrix (n=10). The specimens were exposed from the top surface using 5 LCUs: Valo® Cordless (VA); Radii Plus (RA); Emitter.D (EM), Biolux Plus (BI), Woodpecker® (WO). The emission wavelength and the power density was determined. After the photoactivation, the Raman vibrational modes were calculated taking as reference the peaks at 1,601 (aromatic bonds C=C) and 1,640 cm-1 (aliphatic bonds C=C). RESULTS: The largest difference in DC in 20s, comparing the values obtained in the first and last layer is for BI, with a variation from 61.24% to 53.86%. Comparing the LCUs, the last layer in 40s DC values are 57.40% (BI), 58.21% (WO), 58.97% (VA), 60.90% (RA) and 62.42% (EM). The higher the dose (J/cm²) and the close the λmax is to the maximum CQ absorption length (λmax ~ 470 nm) the better the DC value. CONCLUSIONS: There was a significant difference in the DC values between the LCUs with increasing depth of the bulk-fill increments. Results indicate significant differences in DC among the different LCUs as well as enhanced DC when using 40s exposure compared to 20s. It is suggested that for DC improvement using lower power photoactivator increase the exposure time the exposure time should be 20s to 40s. Key words:Polymerization, Composite Resins, Raman spectroscopy.

Profile of victims of accidents with biological material in a course of Dentistry / Perfil das vítimas de acidentes com material biológico em um curso de Odontologia

ABSTRACT Objective: To identify the epidemiological profile of accidents with biological material occurring in the dental clinic of a university in the southern region of the country. Methods: This is a descriptive, cross-sectional, retrospective study, which analyzed the reports of the Epidemiological Surveillance (SINAN) that occurred between March 2013 and December 2016. We analyzed the demographic variables and data related to the notification of accidents with biological material in the SINAN file, such as: age, sex, race, occupation (student, teacher, oral health technician, residents), time and place of occurrence of the accident, agent causing the perforation, total or partial use of PPE (personal protective equipment) at the time of accident, contact with organic material, contact agent and up-to-date vaccination against hepatitis B and treatment withdrawal. The data obtained were analyzed in EpiInfo Software. Statistical analysis included descriptive and inferential analysis, with significance level of p?0.05 and confidence interval (CI) of 95%. Results: In total there were 55 reports of accidents with piercing-cutting materials, of which 12 were men (21.82%) and 43 were women (78.18%). The mean age of the sample population was 24.2 (± 6.3) years. Regarding the occupation, 80% (n = 44) were undergraduate students, 12.72% were residents, 5.45%, teachers and 1.82%, oral health technicians. The majority (61.8%) were perforated during the dental procedure, 21.82% during material washing and 16.36% during surgery, but 20% claimed that they did not use any personal protective equipment. Regarding the organic material, there was a high prevalence of contact with blood, 70.9%, the needle was the main agent (n = 26; 47.3%). Still, 3.7% stated that they were not vaccinated against hepatitis B. In the bivariate analysis, the site of the accident was associated with the use of personal protective equipment (p = 0.01). Conclusion: The results showed that the number of incidents is high and can be attributed to several factors, such as lack of experience of students and the non-use of personal protective equipment. As a result, it is necessary to establish a permanent education program focused on education and accident prevention strategies to minimize these problems.

RESUMO Objetivo: Identificar o perfil epidemiológico dos acidentes com material biológico ocorridos na clínica odontológica de uma universidade na região sul do país Métodos: Foi realizado um estudo descritivo, transversal, retrospectivo, analisando as notificações da Vigilância Epidemiológica (SINAN) ocorridas entre março de 2013 a dezembro de 2016. Foram analisadas as variáveis demográficas e os dados referentes a notificação de acidentes com material biológico contidas na ficha do SINAN, tais como: idade, sexo, raça, ocupação (estudante, professor, técnico em saúde bucal, residentes), momento e local da ocorrência do acidente, agente causador da perfuração, uso total ou parcial de EPI no momento do acidente, contato com material orgânico, agente do contato e vacinação em dia contra hepatite B e abandono do tratamento. Os dados obtidos foram analisados pelo Software EpiInfo. A análise estatística incluiu a análise descritiva e inferencial, com nível de significância de p?0,05 e intervalo de confiança (IC) de 95%. Resultados: No total houve 55 notificações de acidentes com materiais pérfuro-cortantes, sendo doze homens (21,82%) e 43 mulheres (78,18%). A idade média da população amostral era de 24,2 (±6,3) anos. Quanto à ocupação, 80% (n=44) eram estudantes de graduação, 12,72% residentes, 5,45% professores e 1,82% técnico em saúde bucal. A maioria (61,8%) se perfurou durante o procedimento odontológico, 21,82% durante a lavagem dos materiais e 16,36% durante uma cirurgia, porém 20% alegaram que não utilizavam o equipamento de proteção individual. Em relação ao material orgânico, houve grande prevalência do contato com o sangue 70,9%, sendo a agulha o principal agente (n=26; 47,3%). Ainda, 3,7% afirmaram não estavam vacinados contra hepatite B. Na análise bivariada, o local do acidente esteve associado com o uso do equipamento de proteção individual (p=0,01). Conclusão: Os resultados mostraram que o número de incidentes é elevado e podem ser atribuídos a diversos fatores, como a falta de experiência dos estudantes e a não utilização de equipamentos de proteção individual. Em decorrência disso, é necessário estabelecer um programa de educação permanente focado em estratégias de educação e prevenção de acidentes para minimizar esses agravos.