Efeito dos diferentes tipos de polimento sobre a rugosidade de superfície de uma resina acrílica comercial quimicamente ativada: estudo in vitro / Effect of different types of polishing on the surface roughness of a chemically activated commercial acrylic resin: an in vitro study

Objetivo: avaliar in vitro o polimento sobre resina acrílica quimicamente ativada (RAQA), por meio da rugosidade de superfície (Ra). Materiais e Método: Foram confeccionadas 40 amostras de RAQA, com dimensões de 10 a 10 x 2 mm, e foram divididas em quatro grupos (n=10): ausência do acabamento (AA); Ausência de polimento (AP); Polimento químico (PQ); Polimento com borrachas siliconadas + Escovas (PM). Os espécimes foram avaliados no quanto a rugosidade média (Ra) antes e após o envelhecimento em água destilada em uma estufa por 60 dias. Três medições de Ra (µm), na horizontal foram realizadas e calculada uma média para cada espécime. Os dados foram analisados de forma descritiva e inferencial, ANOVA de medidas repetidas e teste de Tukey com nível de significância de 5%. Resultados: Inicialmente, o grupo AA teve os menores valores de Ra e o grupo AP os maiores valores de rugosidade, com média e desvio padrão respectivamente 0,17 (±0,11) e 0,52 (±0,10). Após o envelhecimento, o grupo AA teve as menores médias e o grupo PQ os maiores valores de Ra, sendo 0,38 (±0,20) e 1,33 (±0,32), respectivamente. Os resultados evidenciaram diferença estatística significante quando as amostras foram submetidas ao acabamento com brocas. Conclusão: A RAQA necessita de polimento após acabamento com brocas, uma vez que a ausência de polimento comprometerá a lisura de superfície do material.(AU)

Objective: to evaluate in vitro polishing on chemically activated acrylic resin (RAQA), using surface roughness (Ra). Materials and Method: 40 RAQA samples were made, measuring 10 to 10 x 2 mm, and divided into four groups (n=10): absence of finishing (AA); Lack of polishing (AP); Chemical polishing (PQ); Polishing with silicone rubbers + Brushes (PM). The specimens were evaluated for their average roughness (Ra) before and after aging in distilled water in an oven for 60 days. Three horizontal Ra (µm) measurements were taken and an average was calculated for each specimen. Data were analyzed descriptively and inferentially, using repeated measures ANOVA and Tukey test with a significance level of 5%. Results: Initially, the AA group had the lowest Ra values and the AP group the highest roughness values, with mean and standard deviation respectively 0.17 (±0.11) and 0.52 (±0.10). After aging, the AA group had the lowest averages and the PQ group the highest Ra values, being 0.38 (±0.20) and 1.33 (±0.32), respectively. The results showed a statistically significant difference when the samples were finished with drills. Conclusion: RAQA requires polishing after finishing with drills, as the lack of polishing will compromise the surface smoothness of the material.(AU)

Stability of Denture Base Acrylic Resin to Tea, Coffe and Turmeric Solutions: An in Vitro Study

Background: The color stability of commercially available denture base acrylic resins (Lucitone-199, DPI and Travelon-HI) was studied in vitro. Material & Methods: The specimens were exposed to tea, coffee and turmeric solutions at 37 ± 1 °C. Colour measurement of the specimens from each brand of denture base acrylic resin recorded by spectrophotometer. The specimens were washed under distilled water and dried before measuring the colour on 0, 10, 20 and 30 days of immersion and color differences were calculated. Results: Statistically the colour change was significant between and within the groups of different heat cure denture base acrylic resins. Conclusion: Where as Lucitone-199 heat cure showed the highest colour variation in tea and coffee followed by DPI and Travelon-HI.

Longitudinal Evaluation of Ethyl Cyanoacrylate Adhesives on Candida albicans Biofilm

ABSTRACT: The aim of this study is to evaluate the effect of two ethyl cyanoacrylate-based adhesives on the growth of Candida albicans biofilms on a heat-polymerized resin, after 7, 14, and 30 days of exposure. Ninety circular (10 x 2 mm) heat-polymerized resin specimens were equally divided into three groups: control, conventional ethyl cyanoacrylate (ECAc), and ethyl cyanoacrylate gel (ECAg). Two layers of 50 µL of each material were applied to the respective groups. C. albicans SC5314 strain was activated and standardized to 107 cells/mL-1. Specimens were immersed in 1 mL of artificial saliva and deposited in 1 mL fungal suspension, washed, and immersed in 1 mL of RPMI for 7, 14, and 30 days. The medium was changed at 48-hour intervals. The final suspension was diluted (10 -1 to 10-4) and deposited on Sabouraud dextrose agar for 48 h at 37 °C. After this period, the colonies were quantified using the CFU/mL calculation. Data were evaluated using one- way ANOVA and Tukey's test for post-hoc analysis (P=0.05). It was observed that both adhesives significantly reduced (P<0.05) biofilm formation compared to the control at all evaluated periods. In conclusion, an immediate and long-term inhibitory effect on C. albicans biofilm formation was observed.

RESUMEN: El objetivo del estudio fue evaluar el desarrollo microbiano en superficies de resina acrílica de termopolimerización, acondicionadas previamente, con adhesivos a base de etil cianoacrilato después de 7, 14 y 30 días de exposición en biofilm de Candida albicans. Noventa muestras circulares (10 x 2 mm) de resina acrílica de termopolimerización se dividieron por igual en tres grupos: control, etil cianoacrilato convencional (ECAc) y etil cianoacrilato en gel (ECAg). Se aplicaron dos capas de 50 µl de cada adhesivo en cada muestra. Simultáneamente, se activó la cepa C. albicans SC5314 y se estandarizó a 107 células/ml-1. Las muestras fueron sumergidas en 1 mL de saliva artificial por dos horas y luego se depositó 1 mL de suspensión fúngica por una hora. En seguida cada muestra se lavó y se sumergió en 1 mL de RPMI durante 7, 14 y 30 días, con cambios del medio a cada 48 horas. La suspensión final se diluyó (10-1 a 10-4) y se depositó en agar dextrose Sabouraud durante 48 h a 37° C. Después de este período, las colonias se cuantificaron mediante el cálculo de UFC / mL. Los datos obtenidos se evaluaron por medio del test ANOVA-one way y la prueba de Tukey para el análisis post- hoc (p = 0,05). Se observó que ambos adhesivos redujeron significativamente (P<0,05) la formación del biofilm de Candida albicans al ser comparados con el grupo control en todos los períodos evaluados. Los adhesivos a base de etil cianoacrilato poseen un efecto inhibidor de biofilm de Candida albicans de hasta 30 días, al ser aplicados dos veces en resinas acrílicas de termopolimerización.

Effect of silver-coated silica nanoparticles on the thermal conductivity of thermally activated acrylic resin / Efeito das nanopartículas de sílica revestidas por prata na condutividade térmica da resina acrílica ativada termicamente

Objective: Thermally activated acrylic resins (RAATs) are widely used in dentures as a base material due to their good dimensional stability and biocompatibility. However, their low thermal conductivity is a disadvantage, as it affects acceptance when using dental prostheses. Thus, the objective of this work was to measure the conduction heat in RAATs with and without incorporation of silica and silver nanoparticles (NP) and rigid reline (RR). Material and Methods: For this, samples were made and divided into 10 groups (n = 6). The first five groups were 2-mm-thick samples: G1 (RAAT control), G2 (RAAT + RR control), G3 (RAAT and NP + RR), G4 (RAAT + RR and NP), and G5 (RAAT and RR modified by NP). In the other five groups, 8-mm-thick samples were made: G6 (RAAT control), G7 (RAAT + RR control), G8 (RAAT and NP + RR), G9 (RAAT + RR and NP), and G10 (RAAT and RR modified by NP). The heat that cross the surface of the specimens was quantified using a wireless device. The data were submitted to two-factor ANOVA statistical analysis and Tukey ́s test with a 5% significance level. Results: After measuring the temperature variation as a function of time, it can be observed that there was a statistically significant difference for thermal conduction between the control groups and those modified with NP. Conclusion: Thus, it was possible to conclude that the NP improved the heat conduction in RAAT and in the RR because the nanoparticles have a higher thermal conductivity. (AU)

Objetivo: As resinas acrílicas termicamente ativadas (RAATs) são amplamente utilizada em próteses dentárias como material de base, pois possuem uma boa estabilidade dimensional e biocompatibilidade. Porém, como desvantagem, possuem baixa condutividade térmica, o que prejudica a aceitação do uso de próteses dentárias. Assim, o objetivo deste trabalho foi medir a condução de calor em RAAT com e sem incorporação de nanopartículas de sílica e prata (NP) e reembasador rígido (RR). Material e Métodos: Para isso, foram confeccionadas amostras que foram divididas em 10 grupos (n=6). Os primeiros cinco grupos eram amostras de 2 mm de espessura: G1 (RAAT controle), G2 (RAAT + RR controle), G3 (RAAT e NP + RR), G4 (RAAT + RR e NP) e G5 (RAAT e RR modificados por NP). E nos outros cinco grupos foram feitas amostras com espessura de 8 mm: G6 (RAAT controle), G7 (RAAT + RR controle), G8 (RAAT e NP + RR), G9 (RAAT + RR e NP) e G10 (RAAT e RR modificados por NP). O calor percorrido pela superfície dos corpos ­ de prova foi quantificado por meio de um dispositivo sem fio. Os dados foram submetidos à análise estatística ANOVA dois fatores e teste de Tukey com 5% de significância. Resultados: Após medir a variação da temperatura em função do tempo, pode-se observar que houve diferença estatisticamente significante para a condução térmica entre os grupos controle e os modificados com NP. Conclusão: Assim, foi possível concluir que a NP melhorou a condução de calor na RAAT e no RR, pois as nanopartículas apresentam maior condutividade térmica. (AU)

Comparación del módulo de elasticidad y resistencia de la resina acrílica de termocurado y la resina flexible superpoliamida. Estudio in vitro / Comparison of the module of elasticity and resistance of thermal curing acrylic resin and flexible superpolyamide resin. An in vitro study

Objetivo: Comparar el módulo de elasticidad y resistencia de la resina acrílica de termocurado y la resina flexible superpoliamida. Métodos: Se diseñó un estudio experimental que empleó dos tipos de resinas acrílicas preparadas en cera para obtener una forma rectangular de 64 mm de largo, 10 mm de ancho y 2,5 mm de grosor, pasadas a acrílico de termocurado y resina flexible superpoliamida. Se emplearon 10 bloques de resina acrílica de cada tipo sometidas a compresión por la máquina de ensayos universal, que generó una fuerza de aproximación de 0,001 N sobre los bloques con un avance de 0,01 mm/min. El módulo de resistencia y el módulo de elasticidad se analizaron mediante la prueba de flexión de tres puntos. Resultados: El módulo de elasticidad de la resina acrílica de termocurado fue de 2501,83 ± 139,42, mientras que el módulo de resistencia fue de 78,36 ± 11,69 MPa. Por otro lado, el módulo de elasticidad de la resina flexible superpoliamida fue de 1020,59 ± 92,95, mientras que el módulo de resistencia fue de 36,04 ± 2,71 MPa. El módulo de elasticidad de la resina acrílica de termocurado fue mayor al de la resina flexible superpoliamida, esta diferencia fue de 1481,24 MPa. El módulo de resistencia de la resina acrílica de termocurado fue mayor al de la resina flexible superpoliamida. Conclusiones: Se concluyó que el módulo de elasticidad (rigidez) y resistencia fue mayor en la resina acrílica de termocurado en comparación a la resina flexible superpoliamida(AU)

Objective: Compare the module of elasticity and resistance of thermal curing acrylic resin and flexible superpolyamide resin. Methods: An experimental study was conducted of two types of acrylic resins molded in wax to obtain a 64 mm long, 10 mm wide and 2.5 mm thick rectangular shape, and then transferred to thermal curing acrylic resin and flexible superpolyamide resin. Ten acrylic resin blocks of each type were used. The blocks were compressed by the universal testing machine, which generated an approximation force of 0.001 N on the blocks at a forward speed of 0.01 mm/min. The resistance module and the elasticity module were analyzed with the three point flexural test. Results: The elasticity module of the thermal curing acrylic resin was 2501.83 ± 139.42, whereas the resistance module was 78.36 ± 11.69 MPa. The elasticity module of the flexible superpolyamide resin was 1020.59 ± 92,95, whereas the resistance module was 36.04 ± 2.71 MPa. The elasticity module of the thermal curing acrylic resin was greater than that of the flexible superpolyamide resin, the difference being 1481.24 MPa. The resistance module of the thermal curing acrylic resin was greater than that of the flexible superpolyamide resin. Conclusions: The elasticity (rigidity) and resistance module was greater in the thermal curing acrylic resin than in the flexible superpolyamide resin(AU)

Comportamiento cromático de resinas acrílicas y bisacrílicas para restauraciones provisionales / Chromatic behavior of acrylic and bisacrylic resins used for provisional restorations

Introducción: Las prótesis provisionales son restauraciones usadas en prótesis fijas durante un tiempo, hasta la cementación de la prótesis definitiva. Uno de los problemas que presentan este tipo de restauraciones es el cambio de color, que afecta a la estética y, en consecuencia, produce sensación de desagrado en los pacientes. Objetivo: Evaluar, para restauraciones provisionales, con y sin el pulido final de la superficie, la estabilidad del color de dos resinas al ser sumergidas en café. Métodos: Estudio experimental in vitro, realizado en el Laboratorio de Prótesis de la Facultad de Odontología de la Universidad Nacional del Nordeste, Corrientes-Argentina, 2019. Se comparó una resina acrílica (Duralay®) con una bisacrílica (ProtempIV 3M®) para restauraciones provisionales. Se elaboraron 40 discos de resinas a partir de moldes metálicos de 25 mm de diámetro y 2 mm de espesor. Se utilizaron 20 discos para cada tipo de resina, de ellos, 10 pulidos y 10 sin pulir. Las muestras fueron almacenadas en agua destilada en estufa a 37 °C durante 24 h para hidratarlos. Luego se procedió a la toma del color. Con posterioridad, cada grupo se sumergió en café, manteniéndolos en estufa a 37 °C durante 24 h más. Seguidamente, se realizó la segunda toma del color. Se utilizó el colorímetro Kónica Minolta®, determinando la diferencia total de color ΔE. Para el análisis estadístico se utilizó ANOVA una vía y test de Tukey para identificar la diferencia entre grupos. Resultados: Se observó en el grupo de resina acrílica pulida una diferencia ΔE = 0,82 ± DS = 0,22 y de ΔE = 3,86 ± DS = 0,30 sin pulido. En el grupo de resina bisacrílica pulido se obtuvo ΔE = 4,84 ± DS = 0,25 y, para el no pulido, ΔE = 5,85 ± DS = 0,29. Conclusiones: Se comprobaron diferencias significativas en la estabilidad del color de ambas resinas. La resina bisacrílica fue la menos estable, independientemente del pulido(AU)

Introduction: Provisional prosthesis are restorations used in fixed prostheses for a while, until the definitive prosthesis is cemented. One of the problems posed by this type of restoration is the change in color, which affects esthetics and therefore creates a feeling of displeasure in patients. Objective: Evaluate, in the case of provisional restorations with and without final surface polish, the color stability of two resins when soaked in coffee. Methods: An in vitro experimental study was conducted in the Prosthesis Laboratory at the Dental School of the National University of the Northeast in Corrientes, Argentina, in the year 2019. A comparison was made of an acrylic resin (Duralay®) versus a bisacrylic resin (ProtempIV 3M®) for provisional restorations. Forty resin disks were made from metal molds 2 mm thick and 25 mm in diameter. Twenty disks were used for each type of resin, of which 10 were polished and 10 were not. The samples were stored in distilled water in a stove at 37ºC for 24 h to hydrate them. Color measurements were then taken. Next, each group was soaked in coffee and kept in the stove at 37ºC for another 24 h. A second color measurement was then taken. A Konica Minolta® colorimeter was used to determine total color difference ΔE. Statistical analysis was based on one-way ANOVA and Tukey's test was used to identify the difference between the groups. Results: In the polished acrylic resin group a difference was found of ΔE = 0.82 ± SD = 0.22, whereas in the non-polish group the difference was ΔE = 3.86 ± SD = 0.30. In the polished bisacrylic resin group the difference was ΔE = 4.84 ± SD = 0.25, whereas in the non-polish group the difference was ΔE = 5.85 ± SD = 0.29. Conclusions: Significant differences were found in the color stability of both resins. The bisacrylic resin was the least stable, regardless of polish(AU)

Complete denture hygiene solutions: antibiofilm activity and effects on physical and mechanical properties of acrylic resin

Abstract Appropriated denture hygiene is a predictive factor for longevity of rehabilitation treatment and maintenance of the oral mucosal health. Although, disinfectant solutions are commonly used as denture cleansers, the impact of these solutions on acrylic resin-based dentures remain unclear. Objective To evaluate, in vitro, the antibiofilm activity of complete denture hygiene solutions and their effects on physical and mechanical properties of acrylic resin. Methodology For antibiofilm activity measurement acrylic resin specimens were contaminated with Candida albicans, Candida glabrata and Streptococcus mutans. After biofilm growth, the specimens were assigned to the hygiene solutions: Distilled water (Control); 0.2% Sodium hypochlorite (SH); Efferdent Power Clean Crystals (EPC) and 6.25% Ricinus communis (RC). The viability of microorganisms was evaluated by agar plate counts. In parallel, physical, and mechanical properties of the acrylic resin were evaluated after simulating a 5-year period of daily immersion in the previously mentioned solutions. The changes in surface roughness, color, microhardness, flexural strength, impact strength, sorption and solubility were evaluated. Data were compared by ANOVA followed by the Tukey test or Kruskal-Wallis followed by the Dunn test depending on the distribution (α=0.05). Results Regarding antibiofilm action, SH eliminated all microorganisms while EPC and RC exhibited moderate action against S. mutans (p=0.001) and C. glabrata (p<0.001), respectively. Relative to effects on the physical and mechanical properties of the acrylic resin, RC led to higher values of color change (p=0.030), hardness (p<0.001), surface roughness (p=0.006) and flexural strength (p<0.001). Moreover, RC induced the highest values of changes in solubility (p<0.001). EPC promoted greater changes in surface morphology, whereas immersion in SH retained the initial appearance of the acrylic resin surface. All hygiene solutions reduced the impact strength (p<0.05). Conclusion SH presented the most effective antibiofilm activity. In addition, changes on properties were observed after immersion in RC, which were considered within acceptable limits.

Effect of Different Denture Base Cleansers on Surface Roughness of Heat Polymerised Acrylic Materials with Different Curing Process / Efecto de diferentes limpiadores para dentaduras en la rugosidad de la superficie de acrílicos polimerizados por calor con diferentes procesos de curado

Abstract Avoiding biofilm formation on dentures is associated with maintaining the surface properties of acrylic-based dentures. The aim of the study is to investigate the effects of two different cleaning agents (Corega and Klorhex 0.2% chlorhexidine gluconate) on surface roughness of the denture regarding efficacy of curing procedures. A total of sixty disc-shaped specimens were prepared with two different methods as long and short curing processes. The specimens were divided into subgroups according to the immersion solutions (distilled water, Corega tablet group and Klorhex 0.2% chlorhexidine gluconate group) (n=10). The samples were kept in a solution for 8 hours per day during a month. The average Ra1 (before exposure to the cleanser agent) and Ra2 (after exposure to the cleanser agent) of each sample was measured. A two- way ANOVA and post hoc Tukey test was used for statistical analysis. The solutions significantly increased the Ra values in both acrylic groups (p0.05). The long-term curing time is highly effective in decreasing the surface roughness of the acrylic base material.

Resumen Evitar la formación de biopelículas en las prótesis dentales se asocia con el mantenimiento de las propiedades de la superficie de las prótesis de base acrílica. El objetivo del estudio es investigar los efectos de dos agentes de limpieza diferentes (Corega y Klorhex 0,2% gluconato de clorhexidina) en la rugosidad de la superficie de la dentadura postiza en cuanto a la eficacia de los procedimientos de curado. Se prepararon un total de sesenta muestras en forma de disco con dos métodos diferentes como procesos de curado largos y cortos. Las muestras se dividieron en subgrupos según las soluciones de inmersión (agua destilada, grupo de pastillas Corega y grupo de gluconato de clorhexidina al 0,2%) (n=10). Las muestras se mantuvieron en una solución durante 8 horas al día durante un mes. Se midió el promedio de Ra1 (antes de la exposición al agente de limpieza) y Ra2 (después de la exposición al agente de limpieza) de cada muestra. Para el análisis estadístico se utilizó un ANOVA de dos vías y una prueba post hoc de Tukey. Las soluciones aumentaron significativamente los valores de Ra en ambos grupos acrílicos (p 0,05). El tiempo de curado a largo plazo es muy eficaz para disminuir la rugosidad de la superficie del material de base acrílica.

Strategies for potential toughening of acrylic denture bases polymerized with microwave energy

Abstract Thiourethane additives have been shown to improve properties in several dental polymer applications. The aim of this study was to verify the effect of the addition of thiourethane oligomers and acrylamide or isobornyl-based plasticizers on the physical properties of the denture base acrylic resin polymerized with microwaves. Thiourethane oligomer (TU) was synthetized and added to microwaved acrylic resin in proportions varying between 3 and 14 wt%. Separate experimental groups included the addition of dimethyl acrylamide (DMAM) and isobornyl methacrylate as plasticizers, at concentrations varying from 5 to 20 wt%. Samples were polymerized using microwave energy at 500 Watts for 3 min, deflasked at room temperature, stored in water at 37 °C for 24 h, and evaluated for: linear dimensional change, gloss, Knoop hardness, surface roughness, impact strength, yield strength, elastic modulus, toughness, yield strength, viscosity, glass transition temperature and network heterogeneity, and water sorption/solubility. Data were analyzed with ANOVA/Tukey's post-hoc test (a=5%). The addition of TU led to properties that were similar or worse than the materials to which it was not added, except for dimensional stability. The impact on properties was statistically significant for all materials above 20% addition of TU. The addition of DMAM at 5 wt% or isobornyl methacrylate at 10 wt% improved yield strength and modulus, but increased water sorption and solubility. Except for dimensional stability, the addition of thiourethane oligomers to acrylic denture base materials compromised most tested properties. The use of DMAM and isobornyl methacrylate improved properties for selected compositions.

Resumo Aditivos de tiouretano demonstraram melhorar propriedades de polímeros em diversas aplicações. O objetivo deste estudo foi verificar o efeito da adição de oligômeros de tiouretano, monômeros de acrilamida ou baseados em funcionalidade isobornil na propriedades físicas de bases de dentadura de acrílico polimerizadas em micro-ondas. O oligômero de tiouretano (TU) foi sintetizado e adicionado à resina acrílica em proporções variando de 3 a 14% em peso. Dimetil acrilamida (DMAM) e isobornil metacrilato (IBMA) foram adicionados em formulações separadas como plastificantes em concentrações variando de 5 a 20% em peso. As amostras foram polimerizadas usando energia de micro-ondas (500 Watts oor 3 min), desincluídas da mufla a temperature ambiente, armazenadas em água a 37°C por 24 h, e submetidas aos testes de: alteração dimensional linear, brilho, dureza Knoop, rugosidade superficial, resistência ao impacto, tensão normal de escoamento, módulo de elasticidade, tenacidade, viscosidade, temperatura de transição vítrea e heterogeneidade da rede polimérica, além de sorção de água e solubilidade. Os dados foram analisados com ANOVA e teste de Tukey (a=5%). A adição de TU não afetou ou diminuiu todas as propriedades, exceto pela estabilidade dimensional. O impacto nas propriedades foi estatisticamente significante para todos os materiais em concentrações acima de 20% de TU. Isso pode ser explicado por um encurtamento das cadeias e diminuição do empacotamento das cadeias lineares do PMMA. A adição de 5% de DMAM ou 10% de isobornil metacrilato melhoraram a tensão de escoamento e o módulo, mas aumentaram a sorção de água e solubilidade. Exceto pela estabilidade dimensional, a adição de oligômeros de tiouretano à bases de dentatura compostas por resina acrílica prejudicou todas a propriedades testadas. O uso de DMAM e isobornil metacrilato melhorou as propriedades para composições selecionadas.

Comparative Study of Bisphenol A Release from Various Orthodontic Adhesive and Myofunctional Appliances - An In-Vitro Study.

We wanted to compare & evaluate, regularly used orthodontic materials including adhesives & myofunctional appliances for release of Bisphenol A. MethodsBisphenol - A release was assessed from two materials - orthodontic adhesive resin and heat cure acrylic resin [twin block]. Based on materials used, a total of 40 samples was assigned into two groups; Group A and Group B, each containing 20 samples. For Group A [orthodontic adhesive resin], metal brackets were bonded to 20 bicuspid teeth using adhesive resin and cured with LED light. For group B, 20 twin block appliances made from heat cured acrylic resin were used. Then, samples from both the groups were immersed in artificial saliva and then subjecting to thermal treatment from hot (60 ˚C) to cold (4 ˚C) temperatures, followed by shaking for 5 minutes. The samples were again shaken at (37 ˚C) and 1.0-mL aliquots were removed at 24 hours and 7 days after insertion. Gas chromatography / mass spectroscopy was used for the evaluation of leaching of bisphenol A from artificial saliva. ResultsSignificant results were found after 24 hours of analysis in both groups where 70 % samples from group A had bisphenol A release, whereas 80 % samples from group B had bisphenol A release. However, a non-significant result was obtained after 7 days where 20 % samples from group A had bisphenol A release whereas 60% samples from group B had bisphenol A release. The Heat cure acrylic group showed higher Bisphenol - A than that of orthodontic adhesive resin group. It was seen that the levels were lower than the reference dose which were calculated for daily consumption but were statistically significant. CoclusionsBisphenol A is considered as an endocrine disruptor. Degradation of orthodontic materials results in leaching of Bisphenol-A into oral cavity which is a clinical concern.

Evaluation and comparison of different polymerization techniques, curing cycles, and thicknesses of two denture base materials

Purpose: The study aimed to compare the effect of different materials, thicknesses, and polymerization methods and cycles, on the surface porosity of acrylic denture base resins. Materials and Methods: Conventional heat-polymerized polymethyl methacrylate (PMMA) and specially designed acrylic resin (Acron MC) were used to make 84 rectangular samples. They were divided into three groups to evaluate and compare the polymerization techniques, curing cycles, and thicknesses of the two denture base materials (28 samples each). Group A contained PMMA samples polymerized using water bath method (control group); Group B contained Acron MC samples polymerized by microwave method, and Group C contained PMMA samples polymerized by microwave method. Each group was further divided based on sample thickness and polymerization cycles. Each sample was scanned for surface porosity and area of each pore was measured using optical microscope. Data was analyzed using ANOVA, Bonferroni, and student t-tests. Unpaired student t-test was performed to compare the means of surface porosity with polymerization cycles and thicknesses among the groups. The power of study was kept at 80%. Results: Group C showed highest mean % of porosity depending on method of polymerization, different polymerization cycles (short and long) and polymerization cycles within the group. Group B showed the highest mean % of porosity depending on thickness and thickness within the groups. Conclusions: Microwavable acrylic resin polymerized by microwave energy exhibited statistically insignificant increase in porosity when compared to conventional heat cured acrylic resin by water bath method. Conventional acrylic resin polymerized by microwave energy exhibited high statistically significant porosity irrespective of sample thickness. There was statistically insignificant increase in porosity depending on sample thickness irrespective of material and method of polymerization.

Evaluation of Anti Candida Effect of Melaleuca alternifolia on Heat Cured Acrylic Resin

Objectives: To evaluate the anti-candida properties of tea tree oil as an additive to heat cured acrylic resin. Materials and methods: Total 24 heat cured samples were prepared without the addition of oil (control), and 24 with additives (20% of pure natural tea tree oil). These disks were inoculated with 0.1 mL of Candida albicans standard inoculum and were rinsed with 0.9% NaCl to remove the loosely attached cells from the surface of the discs. Sabouraud’s dextrose agar plate was used for measuring the attached yeast. The control and treated disks have been placed in distilled water for 1 day, 21 days and 42 days and washed daily with wet cotton. Results: CFU the mean colony forming units for control disks were placed in water and cleaned with wet cotton for 1 day, 21 days and 42 days was 1.5000, 5.0000, 1.0000, respectively and CFU for disks with tea tree oil decreased to 0.8750, 1.6250 and 0.3750 after 1 day, 21 days and 42 days. Tea tree oil incorporated specimens were effective in reducing the growth of C. albicans after storage for 42 days in distilled water. Conclusion: There was a significant reduction in the growth of C. albicans after the addition of oil to heat cured acrylic resin which suggests a new oral topical treatment for denture stomatitis.

Evaluation of the effect of denture cleansers on the surface roughness of hard denture base material: An In vitro study

Maintaining the oral hygiene of denture wearers is a challenge faced in modern dentistry. Biofilm formed on dentures has been associated with denture stomatitis, malodor, aspiration pneumonia, infectious endocarditis, gastrointestinal infection, and chronic obstructive pulmonary disease. Objective: The purpose of this study was to evaluate the effect of denture cleansers on the surface roughness of hard denture base material. Materials and Methods: A total of 100 heat-cure acrylic resin specimens were fabricated with dimensions 30 mm × 15 mm × 3 mm in length, width, and thickness, respectively. All specimens were distributed into four groups randomly. Three commonly prescribed denture cleansers were used for immersion in this study. Regular tap water was used for immersion in the control group. Surface roughness was determined before immersion and after immersion in denture cleansing solutions using contact profilometer. The data were subjected to statistical analysis using paired t-test, one-way analysis of variance, and Tukey's multiple post hoc test. Results: The change in surface roughness of acrylic samples immersed in Clanden group was statistically significant (P < 0.05) at individual group level. However, the change in surface roughness of acrylic samples after immersion, when compared between the groups, namely, control, Clinsodent, Clanden, and Fittydent, was not statistically significant (P > 0.05). Conclusion: Within the limitation of this study, the three denture cleansing materials, namely, Clinsodent powder, Clanden tablet, and Fittydent tablet, are safe to be prescribed as denture cleansers.

Influence of indirect reinforcements on the flexural strength of a thermally activated acrylic resin used for complete dentures / Influência de reforços indiretos na resistência a flexão de uma resina acrílica ativada térmicamente utilizada na confecção de próteses totais

Objective: This research aimed to verify the performance of thermally activated acrylic resin (TAAR) combined with a mix of glass and aramid fibers and/or composite resin of indirect use by a tree point bending test. Material and Methods: Ten samples, with 65 x 10 x 2.5 mm, were prepared for each group (n = 10): CO, control of only TAAR; CR, in which an 60 mm indirect composite resin was polymerized together with the acrylic resin during the thermo-polymerization cycle; SS, in which ceramic glass mixed with aramid fibers cut 60 mm in length were incorporated into the samples; and SC, in which the same fibers were incorporated with addiction of the indirect composite resin. A three point flexural strength test was performed with a universal testing machine with a load of 50KgF at a speed of 5 mm/min in the center of the samples supported by a suitable device. The reinforced face was placed to the tensile side. The statistical one way ANOVA and Tukey tests were made with a significance level of 95%. Results: The mean value for the CO was 60,27 ± 24,18 MPa, for CR it was 38,39±12,75 MPa, for SS it was 79,97±12,75 Mpa and for CS it was 32,40±9,05 MPa. Conclusion: The use of glass and aramid fibers at the base of a TAAR increased the three-point flexural strength, however when indirect composite resin was incorporated, a significant drop of this mechanical property was observed. (AU)

Objetivo: Esta pesquisa teve como objetivo verificar o desempenho de uma resina acrílica ativada termicamente (RAAT) combinada com uma mistura de fibras de vidro e aramida e / ou resina composta de uso indireto por um teste de flexão de três pontos. Material e Métodos: Foram preparadas dez amostras, com 65 x 10 x 2,5 mm, para cada grupo (n = 10): CO, controle com apenas RAAT; CR, em que uma resina composta indireta de 60 mm com polimerizada em conjunto com a resina acrílica durante o ciclo de termopolimerização; SS, em que o vidro cerâmico misturado com fibras de aramida cortadas com 60 mm de comprimento foi incorporado nas amostras; e SC, nas quais as mesmas fibras foram incorporadas em conjunto com a resina composta indireta. O teste de resistência à flexão de três pontos foi realizado em uma máquina de teste universal com uma carga de 50 KgF a uma velocidade de 5 mm/min no centro das amostras suportadas por um dispositivo adequado. A face reforçado foi colocado no lado da tração. Os testes estatísticos one-way ANOVA e Tukey foram feitos com um nível de significância de 95%. Resultados: O valor para o CO foi de 60,27 ± 24,18 MPa, para CR foi de 38,39 ± 12,75 MPa, para SS foi de 79,97 ± 12,75 Mpa e para CS foi de 32, 40 ± 9,05 MPa. Conclusão: o uso de fibras de vidro e aramida na base de uma RAAT aumentou a resistência à flexão de três pontos, no entanto, quando a resina composta indireta foi incorporada, observou-se uma queda significativa dessa propriedade mecânica (AU)

Avaliação da atividade antimicrobiana, análise elementar e da lixiviação da resina acrílica autopolimerizável modificada pela incorporação de clorexidina / Evaluation of the antimicrobial, elemental analysis and release of the self-cured acrylic resin modified by the incorporation of chlorhexidine

O objetivo principal do presente estudo, considerando a importância do controle do biofilme, foi avaliar in situ a ação antimicrobiana e análise elementar da incorporação de diacetato de clorexidina(CHX) em resinas acrílicas a base de PMMA. Além disso, avaliar ex vivo o mecanismo de lixiviação da clorexidina por até 14 dias. Primeiramente, foram recrutados 32 indivíduos para utilização de dispositivos acrílicos intraorais palatinos por 24 horas contendo 6 corpos de prova(CPs), sendo subdivididos em 2 grupos: com clorexidina (1%) e sem CHX. A avaliação da atividade antimicrobiana foi realizada por meio de contagem de colônias de microorganismos totais e Estreptococos do grupo mutans. Então, os grupos foram avaliados estatisticamente pelo teste de wilcoxon. A análise estatística aplicada foi o teste de Wilcoxon. No segundo teste, foi feita a análise elementar dos CPs(n=10) por meio das médias das intensidade dos elementos, antes e após o uso do dispositivo, por meio da fluorescência de raio X. Ao final, foi avaliado ex vivo a liberação de clorexidina cumulativa, em meio fechado contendo saliva dos indivíduos(n=5) por até 14 dias, através da ressonância magnética nuclear (RMN). As análises estatísticas da RMN, foram avaliadas pelo programa AMIX e metaboloanalyst. Os resultados mostraram, que para atividade antimicrobiana não houve diferença estatística (p>0,05) entre os grupos. Foi detectado a presença da molécula de clorexidina, antes e após a inserção dos CPs com CHX na cavidade bucal. Já para liberação de clorexidina, foi detectada a droga ao longo de 14 dias em meio fechado para a grupo teste, com liberação maior nas primeiras 24 horas. Conclui-se que, foi comprovada a presença do fármaco na resina acrílica após 24 horas em meio bucal, e seu mecanismo de lixiviação no meio fechado por até 14 dias. Porém, não foram encontrados resultados que confirmem a presença de um potencial antimicrobiano do fármaco, nas concentrações utilizadas nos corpos de prova in situ em 24 horas.

The main objective of the present study, considering the importance of biofilm control, was to evaluate in situ the antimicrobial action and elemental composition of the incorporation of chlorhexidine diacetate (CHX) in acrylic resins based on PMMA. In addition, ex vivo evaluation of the chlorhexidine release mechanism to 14 days. Firstly, 32 individuals were recruited for 24-hour palatal intraoral acrylic devices containing 6 test specimens (SPs), divided into 2 groups: with chlorhexidine (1%) and without CHX. The evaluation of the antimicrobial activity was performed by colonies count of total microorganisms and streptococci mutans group. Then, the groups were statistically evaluated by the wilcoxon test. The statistical analysis applied was the Wilcoxon test. In the second test, elemental analysis of the SPs (n = 10) was done by means of the means intensity of the elements, before and after the use of the device, by X-ray fluorescence. At the end, the release was evaluated ex vivo of cumulative chlorhexidine in a becker containing saliva of the individuals (n = 5) for 14 days, through nuclear magnetic resonance (NMR). The NMR analyzes were evaluated by AMIX and metaboloanalyst. The results showed that for antimicrobial activity there was no statistical difference (p> 0.05) between the groups. The presence of the chlorhexidine molecule was detected before and after the insertion of SPs with CHX in the oral cavity. As for chlorhexidine release, the drug was detected over 14 days in a closed medium for the test group, with a greater release in the first 24 hours. It was concluded that the presence of the drug in the acrylic resin after 24 hours in oral cavity was verified, and its release mechanism in the closed local for 14 days. However, no results were found to confirm the presence of an antimicrobial potential of the drug at the concentrations used in the in situ test specimens in 24 hours

The effect of phase transition process on the characters of transdermal absorption of compound l-carnitine plastics / 中国药学杂志

OBJECTIVE: To explore the effect of phase transition process of compound L-carnitine plastics on the characters of transdermal absorption, provide a theoretical evidence for the penetration enhancing effect produced from phase transition process. METHODS: The accumulated transdermal percentage of capsaicin and L-carnitine were used as measurement indicators, the experiment was finished by improved Franz diffuser and disembodied rabbit skin, the content of different components in transdermal receiving solution and in skin that received in different time was determined by HPLC, the curve of transdermal was drawn been drawn, the rule and the characters of transdermal were analyzed. RESULTS: The transdermal dynamics curve before and after the phase transition of compound L-carnitine plastics is a kind of continuous function, while it become a kind of non-continuous function during the process of the phase transition. The 95% confidence interval of the parameters of transdermal velocity and amount between sample A with transdermal enhancer and sample B without transdermal enhancer shows overlap, the difference shows no statistical significance between sample A and B. It was showed that the sample A have the same transdermal rate and amount as B. While 95% confidence interval of the parameters of transdermal velocity and amount among sample A,B and C (without film-former materials) shows no overlap, the difference shows statistical significance among sample A,B and C. When the capsaicin was used as indicators, the transdermal rate of sample A and B respectively are 1.459 times and 1.450 times of C, the transdermal amount of sample A and B respectively are 2.53 times and 1.907 times of C. When the capsaicin was used as indicators, the transdermal rate of sample A and B respectively are 1.153 times and 1.169 times of C, the transdermal amount of sample A and B respectively are 1.722 times and 1.692 times of C. CONCLUSION: Phase transition process can significantly increase both transdermal rate and transdermal amount of compound L-carnitine plastics, the time increased by phase transition process correspond to film-former time of plastics, the penetration enhancing effect produced from phase transition process is far greater than the penetration enhancing effect produced from transdermal absorption penetration enhancers(P0.05).

Ensaio biomecânico para determinação do diâmetro de barra conectora de polimetilmetacrilato em fixador esquelético externo tipo Ia no úmero de suínos / Biomechanical test to determination the diameter of the polymethylmethacrylate bar in external skeletal fixator type Ia in swine humerusi

Fraturas ósseas podem ser corrigidas com a utilização de fixadores esqueléticos externos (FEE), método de estabilização bastante comum. Para tanto, têm-se utilizado barras conectoras de polimetilmetacrilato (PMMA) sem critério de diâmetro, as quais podem quebrar, se ficarem muito delgadas, ou ocasionar incômodo, quando muito pesadas e volumosas. O objetivo deste trabalho foi testar, por meio de ensaio biomecânico de compressão axial e flexão, qual é o diâmetro ideal da barra conectora de PMMA, correlacionado com o diâmetro ósseo para utilização em FEE tipo Ia. Utilizaram-se 24 úmeros para se realizarem medidas de comprimento, diâmetro, circunferência e ensaios biomecânicos. Após, foram confeccionadas barras de 1,5 vezes a média do diâmetro ósseo (grupo I), do mesmo diâmetro ósseo (grupo II) e de 0,5 vezes o diâmetro (grupo III). Com os resultados obtidos ao se compararem os valores dos ossos com os dos grupos II e III, verificou-se que as barras conectoras do grupo II mostraram-se mais resistentes do que o tecido ósseo no ensaio de compressão. No ensaio de flexão, os ossos resistiram mais quando comparados aos grupos II e III, sendo 4,3 vezes mais resistentes do que o grupo III nesse mesmo ensaio mecânico. Os resultados permitem um direcionamento para confecção de barras considerando-se o diâmetro ósseo como referência.(AU)

Bone fractures can be corrected from external skeletal fixators (ESF) in a fairly common internal stabilization method, in which connector bars polymethylmethacrylate (PMMA) is used. PMMA is used without criterion of diameter, and it can break if it is too thin or too heavy. It can be uncomfortable when bulky. The aim of this study was to test, through biomechanical axial compression and bending which is the ideal connector bar diameter PMMA, correlated to bone diameter for use in type Ia ESF. Twenty-four humerus were used to make measurements of length, diameter, circumference, and biomechanical testing. After the bars confected with 1.5 times the average diameter of the bone (group I), the same diameter (group II) and 0.5 times the diameter of the bone (group III). With the obtained results, using GII and GIII results, it was observed that the connector bars in group II were more resistant than the bones in the compression test. In the bending test, the bones resisted flexion strength when compared to group III and the group II was 4.3 times more resistant than group III in the same mechanical test. The results allow a direction for making bars considering bone diameter as a reference.(AU)

A Narrative Review of Different Types and Processing Methods of Acrylic Denture Base Material

@#Acrylic resin is commonly used to fabricate removable prostheses due to its adequate physical, mechanical properties and cost effectiveness. There has been continuous development of the materials to improve their properties and to widen its application in different clinical setting. To study the history development of the acrylic resin and elaborate on the properties of different types and the processing methods of acrylic resins used to fabricate denture base which are commercially available in the market. This would help the dental clinician in choosing the best material of choice. The authors have summarized the history, development and classification of different types of acrylic resins used in fabricating denture and processing methods based on all the published research available on this topic using published materials available in the Dental Library, University of Malaya and the database (Science Direct, PubMed). Every type of acrylic denture base material has its pros and cons. Therefore, careful selection of material and the processing method is crucial to ensure the best outcome for prosthodontic treatment. Hence, upholding the patients’ best interest and improving their quality of life.

The Effect of Different Curing Condition on the Flexural Strength and Translucency of Orthodontic Acrylic Resin / 대한치과재료학회지

The purpose of this study is to evaluate the effects of polymerization conditions on the flexural strength and transparency of orthodontic acrylic resin. Materials and methods: The specimens were prepared by applying pressure of 1 bar, 2 bar and 4 bar in air, room temperature water, 50℃ water and 70℃ water. The flexural strength of each specimen was measured using a universal testing machine and the translucency parameter (TP) was calculated by measuring the CIE L*a*b* value of each specimen using a spectrophotometer. The flexural strength of orthodontic acrylic resin was the highest in water at 50℃, and the flexural strength was significantly lower in the order of 70℃ water, room temperature water and air (P 0.05). The transparency of orthodontic acrylic resin showed the highest value in air and was significantly lower in the order of room temperature, 50℃ water and 70℃ water (P 0.05). Within the limits of this study, the flexural strength and transparency of the orthodontic acrylic resin differ according to polymerization conditions, but there is no difference according to the pressure.

Novas tendências de combate ao biofilme de Candida em próteses dentárias / New trends to combat Candida biofilm in dental prosthetics

Apesar de a espécie Candida albicans ser efetivamente o microrganismo mais frequentemente associado a estomatite protética, as espécies de Candida não albicans já foram isoladas nas superfícies de dentaduras e da mucosa oral de indivíduos com essa lesão eritematosa. A virulência das espécies de Candida e a capacidade de adesão a polímeros acrílicos são condições prévias para a colonização e o desenvolvimento de biofilmes em superfícies de dentaduras. Estudos recentes focam na tentativa de modificação das resinas acrílicas para diminuir a adesão de cepas patogênicas e formadoras de biofilme do gênero Candida spp. Dentro desse aspecto, esta revisão sistematiza o atual panorama epidemiológico da estomatite protética associada ao uso de próteses dentárias, bem como as atuais e novas opções de combate ao biofilme fúngico especializado na adesão desse tipo de biomaterial. (AU)

Although the Candida albicans species is effectively the microorganism most frequently associated with prosthetic stomatitis, Candida non-albicans species have already been isolated from the denture and oral mucosal surfaces of individuals with this erythematous lesion. The virulence of Candida species and the ability to adhesion to acrylic polymers are preconditions for the colonization and development of biofilms on denture surfaces. Recent studies focus on the attempt to modify the acrylic resins to reduce the adhesion of pathogenic and biofilm forming strains of the genus Candida spp. In this aspect, this review systematizes the current epidemiological panorama of prosthetic stomatitis associated with the use of dental prostheses, as well as new options for combating the fungal biofilm specialized in the adhesion of this type of biomaterial. (AU)