Evaluation of surface roughness, wettability and adhesion of multispecies biofilm on 3D-printed resins for the base and teeth of complete dentures

Abstract Studies evaluating the roughness, wettability and microbial adhesion of 3D-printed resins for complete denture bases and teeth are scarce. Objective This study evaluated the surface roughness, wettability and adhesion of multispecies biofilms (Candida albicans, Staphylococcus aureus and Streptococcus mutans) on 3D-printed resins for complete denture bases and teeth compared to conventional resins (heat-polymerized acrylic resin; artificial pre-fabricated teeth). Methodology Circular specimens (n=39; 6.0 mm Ø × 2.0 mm) of each group were subjected to roughness (n=30), wettability (n=30) and biofilm adhesion (n=9) tests. Three roughness measurements were taken by laser confocal microscopy and a mean value was calculated. Wettability was evaluated by the contact angle of sessile drop method, considering the mean of the three evaluations per specimen. In parallel, microorganism adhesion to resin surfaces was evaluated using a multispecies biofilm model. Microbial load was evaluated by determining the number of Colony Forming Units (CFU/mL) and by scanning electron microscopy (SEM). Data were subjected to the Wald test in a generalized linear model with multiple comparisons and Bonferroni adjustment, as well as two-way ANOVA (α=5%). Results The roughness of the conventional base resin (0.01±0.04) was lower than that of the conventional tooth (0.14±0.04) (p=0.023) and 3D-printed base (0.18±0.08) (p<0.001). For wettability, conventional resin (84.20±5.57) showed a higher contact angle than the 3D-printed resin (60.58±6.18) (p<0.001). Higher microbial loads of S. mutans (p=0.023) and S. aureus (p=0.010) were observed on the surface of the conventional resin (S. mutans: 5.48±1.55; S. aureus: 7.01±0.57) compared to the 3D-printed resin (S. mutans: 4.11±1.96; S. aureus: 6.42±0.78). The adhesion of C. albicans was not affected by surface characteristics. The conventional base resin showed less roughness than the conventional dental resin and the printed base resin. Conclusion The 3D-printed resins for base and tooth showed less hydrophobicity and less adhesion of S. mutans and S. aureus than conventional resins.

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.

Repositioning an Implant-retained Auricular Prosthesis using a Custom Acrylic Base: A Case Report

@#Prosthetic rehabilitation offers an alternative to surgical procedures for repositioning implant-retained auricular prosthesis. This report illustrates a prosthetic rehabilitation of a 15-year- old male with a unilateral microtia who presented with an unfavorable implant-retained left auricular prosthesis. The implants placed seven years ago were drifted posterosuperior away from the ideal ear canal position. The fabrication of a new prosthesis on the existing bar-clip attachment using a custom acrylic base was planned to correct the location. A skin-colour perforated custom acrylic base was fabricated and designed to extend anteriorly, therefore, shifting the prosthesis forwards into a more natural location. The custom base was able to relocate the prosthesis’ position without compromising its retention whilst engaging the existing implant attachment. This in turn enhanced prosthesis acceptability and improved the patient’s confidence. The custom acrylic base serves as a viable option to reposition the prosthesis influenced by age related growth and development.

Carbomer hemorrhoid gel for the treatment of second-degree internal hemorrhoid bleeding / 中国基层医药

Objective:To investigate the clinical efficacy of carbomer hemorrhoid gel in the treatment of second-degree internal hemorrhoid bleeding.Methods:A total of 160 anorectal outpatients with second-degree internal hemorrhoid bleeding who received treatment in Zhuhai Hospital of Integrated Traditional Chinese and Western Medicine from January 2017 to January 2021 were included in this study. They were randomly divided into an observation group and a control group ( n = 80/group). In the observation group, carbomer hemorrhoid gel was used to plug the anus, while in the control group, a hemorrhoid suppository was used to plug the anus. All patients were treated for 7 days. Clinical efficacy was compared between the two groups. Results:After 4 days of treatment, the bleeding score in the observation group was lower than that in the control group [1(0) point vs. 2(1) points, Z = -6.70, P < 0.05). After 7 days of treatment, the bleeding score in the observation group was significantly lower than that in the control group [0(1) point vs. 1(1) point, Z = -4.73, P < 0.05]. After 4 days of treatment, there was no significant difference in the size score of the hemorrhoids between the two groups ( P > 0.05). After 4 days of treatment, the size score of hemorrhoids in the control group did not differ significantly compared with before treatment ( P > 0.05). After 4 days of treatment, the size score of hemorrhoids in the observation group differed significantly compared with before treatment ( Z = -3.16, P < 0.05). After 7 days of treatment, the size score of the hemorrhoids in the observation group was lower than that in the control group [1(1) point vs. 1(0) point, Z = -4.48, P < 0.05]. The total response rate in the observation group was significantly higher than that in the control group [97.5% (78/80) vs. 75% (60/80), Z = -4.50, P < 0.05]. Conclusion:Carbomer hemorrhoid gel is a new drug used to treat hemorrhoids. It has a new dosage form, has no stimulation to the rectum, and is safe to use. Carbomer hemorrhoid gel is highly effective on second-degree internal hemorrhoid bleeding and deserves clinical popularization.

The influence of the retention feature in artificial teeth on its attachment to the thermoplastic resin denture base / Influência da forma de retenção em dentes artificiais de resina acrílica na fixação na base de prótese termoplástica

Objective: Teeth play a crucial role in masticatory efficiency and esthetic harmony making rehabilitation of partially edentulous patients a challenge because of the limitations of conventional removable partial dentures. As a therapeutic alternative, thermoplastic polymers are used in current dental practice either for practical processing purposes or aesthetics. However, it is recognized that the bond between acrylic resin artificial teeth and thermoplastic polymers has no chemical interaction, and depends on retentive features added to the teeth. This study analyzed the efficacy of two retentive forms of features through compressive strength test and as a secondary outcome, fracture and displacement resistance test. Material and Methods: Three groups of samples each with 14 sets of acrylic teeth were compared when two retentive features, single hole and groove retention, and a control group with teeth without any specific form. The experimental unit consisted of six maxillary anterior teeth, positioned in a linear pattern into a polypropylene block, where each tooth was submitted to a static load until its removal, on a universal testing machine. Results: Those specimens with a groove retention presented larger resistance to displacement when compared to the other groups (p <0.05). This was emphasized by the fracture of the tooth tested, with part of the cervical portion remaining embed in the base, and not its displacement as with (or without) the retentive feature. Conclusion: In this study, the type of retention influenced significantly to a better retention considering teeth and thermoplastic polymer base. The data in this study indicates that a groove placed on the artificial tooth offers significantly better retention efficacy to the point where the displacement was only possible after its fracture (AU)

Objetivo: Os dentes são um fator essencial na eficiência mastigatória. A harmonia estética e a reabilitação dos indivíduos parcialmente dentados tornam-se um desafio, frente às limitações das próteses parciais removíveis convencionais. Como uma alternativa terapêutica, os polímeros termoplásticos são utilizados na odontologia contemporânea, tanto para o seu processamento prático como seu apelo estético. Entretanto, pouco se sabe a respeito da união entre a resina acrílica de dentes artificiais e resinas termoplásticas, assim como a influência dos mecanismos de retenção, uma vez que não há interação química entre eles. O objetivo deste estudo foi analisar duas formas de retenção de dentes de resina acrílica a bases de prótese de material termoplástico, por força compressiva e como desfecho secundário, teste de resistência a fratura e deslocamento dos dentes artificiais. Material e Métodos: O presente estudo analisou dois tipos diferentes de retenções: uma cavidade com único ponto e uma canaleta de mesial a distal; e como grupo controle, dentes colocados sem qualquer recurso específico. A unidade experimental consistiu de seis dentes superiores anteriores, posicionados em linha em um bloco de polipropileno. Em cada dente artificial foi aplicada força até a sua remoção, em uma máquina universal de ensaios. Resultados: Os resultados mostraram que a retenção com canaleta apresentou maior força de deslocamento, quando comparado com os outros grupos (p <0,05). Tal fato foi evidenciado pelo teste de fratura e deslocamento, no qual parte da porção cervical do dente artificial permaneceu unida à base, não ocorrendo o deslocamento com (ou sem) a retenção. Conclusão: Neste estudo, o tipo de retenção influenciou de forma significante a retenção de dentes artificiais de resina acrílica a bases de prótese termoplásticas. Os dados deste estudo indicam que a confecção da retenção em canaleta nos dentes artificiais oferece significante aumento na eficiência da retenção, ao ponto em que o deslocamento do dente ocorreu somente após sua fratura (AU).

Effect of Ozonated Water on the Color Stability of Denture Teeth and Heat Polymerized Acrylic Base Resin

Abstract Objective: To determine the effect of ozonated water on the color stability of denture tooth and denture bases. Material and Methods: Thirty denture base discs consisting of 15 Acropars and 15 ProBase Hot specimens with the dimensions of 40 × 5 mm were prepared. Fifteen denture teeth in shade A1 (Ivoclar Vivadent, Schaan, Liechtenstein) were mounted in a specific acrylic jig. All specimens were immersed in three solutions (1% sodium hypochlorite, ozonated water, and distilled water) for four months (one year of clinical use). Color measurements were done with a spectrophotometer and assessed using the CIE L*a*b* colorimetric system (0, 4, 8, 12, and 16 weeks). Data were analyzed using the three-way ANOVA and Tukey test (α=0.05). Results: Tukey's post hoc test revealed a significant change in color in the Acropars denture base for the distilled water group compared to the ozonated water and 1% hypochlorite (p<0.05). Regarding the ProBase Hot denture base, significantly less color change was observed in the 1% hypochlorite group compared to the ozonated water and distilled water (p≤0.001). For the denture teeth, significantly less color change was seen in the distilled water group than in the ozonated water (p=0.015) and 1% hypochlorite (p<0.05) groups. Conclusion: The color change of denture bases and denture tooth in ozonated water are acceptable. Ozonated water can be considered a good disinfectant for cleaning dentures.

Resistência flexural de uma resina para impressão 3D comparada a resinas acrílicas convencionais empregadas para confecção de placas estabilizadoras de mordida / Flexural resistance of 3D printing resin compared to conventional acrylic resins employed to build occlusal bite splints

Introduction: with the technological advance in dentistry, light-polymerized three-dimensional (3D) printing resins had become an alternative for the manufacture of occlusal splint splints. Objective: the present study aimed to analyze the flexural strength of a resin for 3D printing compared to conventional acrylic resins (chemically activated and thermally activated), under the influence of thermocycling. Material and method: 60 specimens were made, which were distributed in six experimental groups (n = 10), according to the resin employed (chemically activated acrylic resin, thermally activated acrylic resin and 3D printing resin) and the treatment received (control and thermocycling). The specimens were submitted to flexural strength by the three-point flexural test. Result: data analysis showed that the material factor (<0.0001) and the thermocycling factor (p = 0.0096) influenced flexural strength, however, the interaction between the two factors did not (p = 0.9728). Conclusion: it was concluded that 3D printing resins presented the lowest flexural resistance to acrylic resins, especially when submitted to thermocycling.

Introdução: com o avanço tecnológico dentro da odontologia, as resinas fotopolimerizáveis para impressão tridimensional (3D) se tornaram uma alternativa para a fabricação de dispositivos interoclusais. Objetivo: o presente trabalho teve como objetivo analisar a resistência flexural de uma resina para impressão tridimensional comparada com resinas acrílicas convencionais (quimicamente ativada e termicamente ativada), sob a influência da termociclagem. Material e método: foram confeccionados 60 corpos de prova, que foram distribuídos aleatoriamente em seis grupos experimentais (n=10), de acordo com a resina utilizada (resina acrílica ativada quimicamente, resina acrílica ativada termicamente e resina para impressão 3D) e com o tratamento recebido (controle e termociclagem). Os corpos de prova foram submetidos ao ensaio de flexão de três pontos para determinação da resistência flexural. Resultado: a análise dos dados demonstrou que o fator material (<0.0001) e o fator termociclagem (p=0.0096) influenciaram a resistência flexural, entretanto, a interação entre os dois fatores não (p=0.9728). Conclusão: deste modo podemos concluir que a resina para impressão 3D apresentou desempenho inferior às resinas acrílicas, especialmente quando submetida a termociclagem.

Effect of different mechanical surface treatments on flexural strength of repaired denture base / Efecto de diferentes tratamientos superficiales mecánicos sobre la resistencia a la flexión de la base de la dentadura reparada

Aim: To assess the effect of different mechanical surface treatments on flexural strength of repaired denture base. Material and Methods: Sixty bar-shaped specimens of heat-polymerized acrylic resin were fabricated, and divided into six groups (n=10). All specimens, except the positive control group (group PC), were sectioned into halves to create a 1-mm clearance. A negative control group with no surface treatment (group NC) was also considered. Other groups underwent different surface treatments: group Laser; treated with erbium: yttrium-aluminum-garnet (Er:YAG) laser, group APA; airborne-particle abrasion (APA), group APA plus Laser; a combination of laser and APA, and group Bur; bur grinding. After measuring surface roughness (Ra) with a profilometer, all sectioned specimens were repaired by auto-polymerizing acrylic resin, and thermocycled afterward. Three-point bending test was performed by a universal testing machine. Data were statistically analyzed (α=0.05). Results: The mean surface roughness of all experimental groups were significantly higher than that of group NC (p<0.05). The mean flexural strength of all groups was significantly lower than that of group PC (p<0.05). Group B had significantly higher flexural strength than the other surface-treated groups (p<0.05). Group Laser had significantly higher flexural strength than groups APA (p=0.043) and APA plus Laser (p=0.023). No significant difference was found between groups APA and APA plus Laser (p=0.684). Conclusion: All surface treatments increased the surface roughness and flexural strength compared with the untreated group. The highest flexural strength was observed in specimens treated by bur grinding and then laser, however, it was still significantly lower than intact specimens.

Objetivo: Evaluar el efecto de diferentes tratamientos superficiales mecánicos sobre la resistencia a la flexión de la base de la prótesis reparada. Material y Métodos: Se fabricaron sesenta especímenes en forma de barra de resina acrílica termo-polimerizada y se dividieron en seis grupos (n=10). Todas las muestras, excepto el grupo de control positivo (grupo PC), se seccionaron en mitades para crear un espacio libre de 1 mm. También se consideró un grupo de control negativo sin tratamiento superficial (grupo NC). Otros grupos se sometieron a diferentes tratamientos superficiales: grupo Láser; tratados con láser de erbio: itrio-aluminio-granate (Er:YAG), grupo APA; abrasión por partículas en el aire (APA), grupo APA más láser; una combinación de láser y APA, y grupo Bur; molienda de fresas. Después de medir la rugosidad de la superficie (Ra) con un perfilómetro, todas las muestras seccionadas se repararon con resina acrílica de autopolimerización y se sometieron a termociclado. La prueba de flexión de tres puntos se realizó con una máquina de prueba universal. Los datos se analizaron estadísticamente (α=0,05). Resultados: La rugosidad superficial media de todos los grupos experimentales fue significativamente mayor que la del grupo NC (p<0,05). La resistencia media a la flexión de todos los grupos fue significativamente menor que la del grupo PC (p<0,05). El grupo B tenía una resistencia a la flexión significativamente mayor que los otros grupos tratados en la superficie (p<0,05). El grupo Láser tuvo una resistencia a la flexión significativamente mayor que los grupos APA (p=0,043) y APA más Láser (p=0,023). No se encontró diferencia significativa entre los grupos APA y APA más Láser (p=0,684). Conclusión: Todos los tratamientos superficiales aumentan la rugosidad de la superficie y la resistencia a la flexión en comparación con el grupo sin tratar. La resistencia a la flexión más alta se observó en las muestras tratadas con fresado y luego con láser; sin embargo, aún era significativamente más baja que las muestras intactas.

Lámina de plástico vs caja de acrílico como dispositivo de barrera durante intubación endotraqueal / Plastic sheet vs. acrylic box as barrier device during endotracheal intubation

Resumen: Introducción: La utilización de dispositivos de barrera adicional para la intubación endotraqueal constituye un reto para la práctica médica durante la actual pandemia. Se pueden utilizar múltiples herramientas para intubación del paciente minimizando la exposición del operador sin afectar la seguridad del procedimiento. El médico debe evaluar y comprender adecuadamente cualquier estrategia adicional, ya que podría interferir con la intubación, aumentando el tiempo de manipulación. Objetivo: Comparar preferencia de los anestesiólogos entre dos dispositivos de barrera, uno diseñado con base en una lámina plástica versus caja de acrílico. Material y métodos: Incluimos 102 pacientes intervenidos de cirugías electivas y de urgencias que aceptaron participar en este estudio prospectivo, transversal y comparativo de manera voluntaria con previo consentimiento informado. Resultados: La lámina de plástico permite un menor tiempo de intubación, menos intentos de laringoscopía y disminuye dificultades de abordaje, además genera un grado de satisfacción mayor en el personal en comparación con dispositivos rígidos como la caja de acrílico. Conclusiones: Es posible obtener buenos resultados para instrumentar la vía aérea cuando se utilizan dispositivos de barrera adicional en personal entrenado. No obstante, teniendo en cuenta los hallazgos de este trabajo existen ventajas con el uso de lámina de plástico.

Abstract: Introduction: The use of additional barrier devices for endotracheal intubation constitutes a challenge for medical practice during the current pandemic. Multiple tools can be used for patient intubation minimizing operator exposure without compromising procedural safety. Any additional strategy must be properly evaluated and understood by the physician as it could interfere with intubation, increasing handling time. Objective: To compare anesthesiologists' preference between two barrier devices, one designed based on a plastic sheet vs an acrylic box. Material and methods: We included 102 patients who underwent elective and emergency surgeries who voluntarily agreed to participate in this prospective, cross-sectional and comparative study with prior informed consent. Results: The plastic sheet allows a shorter intubation time, fewer laryngoscopy attempts and reduces approach difficulties, in addition it generates a higher degree of satisfaction in the personnel compared to rigid devices such as the acrylic box. Conclusions: It is possible to obtain good results to instrument the airway when additional barrier devices are used in trained personnel. However, taking into account the findings of this work, there are advantages with the use of plastic sheeting.

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.

Antibacterial effect of bioactive glass incorporated in acrylic resins against Streptococcus mutans and Lactobacillus acidophilus activity in biofilm / Efeito antibacteriano do vidro bioativo incorporado em resinas acrílicas sobre a atividade de Streptococcus mutans e Lactobacillus acidophilus em biofilme

Objective: The rough surfaces of removable appliances used in pediatric dentistry or orthodontics, may result in an environment for biofilm accumulation, yielding to enamel demineralization. This study aimed to assess the effects of adding nanoparticles of bioactive glass to polymethylmethacrylate to promote the antibacterial activity in acrylic resins. Material and Methods: Acrylic resin specimens (20x20x1mm3) were prepared by adding 2% or 5% bioactive glass. The specimens in the control group without bioactive glass were prepared from the mixture of acrylic powder containing nanoparticles and liquid monomer (n=10 per group). The antibacterial activity of the specimens against Streptococcus mutans and Lactobacillus acidophilus activity in biofilm was investigated through counting colony forming units (CFU). Data were analyzed using a one-way analysis of variance and Tukey's post hoc tests at the significance level of 0.05. Results: The incorporation of 2% (p=0.001) and 5% (p<0.001) bioactive glass in acrylic resin reduced the metabolic activity and CFU of L. acidophilus. For S.mutans, antimicrobial activity was observed only with the 5% concentration of bioactive glass, and this group was statistically different from the control (p<0.001). When L. acidophilus was exposed to polymethyl methacrylate with 5% bioactive glass, significant decrease was observed compared to the control group (p<0.05). Conclusion: Adding bioactive glass nanoparticles into the acrylic resins used for fabricating removable appliances revealed a greater antibacterial effect against cariogenic bacteria tested (AU)

Objetivo: As superfícies rugosas dos aparelhos removíveis utilizados em Odontopediatria ou Ortodontia, podem resultar em um ambiente para acúmulo de biofilme, cedendo à desmineralização do esmalte. Este estudo teve como objetivo avaliar os efeitos da adição de nanopartículas de vidro bioativo ao polimetilmetacrilato para promover a atividade antibacteriana em resinas acrílicas. Material e Métodos: Amostras de resina acrílica (20x20x1 mm3) foram preparadas pela adição de 2% ou 5% de vidro bioativo. Os corpos de prova do grupo controle sem vidro bioativo foram preparados a partir da mistura de pó acrílico contendo nanopartículas e monômero líquido (n=10 por grupo). A atividade antibacteriana dos espécimes sobre a atividade de Streptococcus mutans e Lactobacillus acidophilus em biofilme foi investigada através da contagem de unidades formadoras de colônias (UFC). Os dados foram analisados por meio de análise de variância unidirecional e testes post hoc de Tukey com nível de significância de 0,05. Resultados: A incorporação de 2% (p=0,001) e 5% (p<0,001) de vidro bioativo em resina acrílica reduziu a atividade metabólica e UFC de L. acidophilus. Para S. mutans, a atividade antimicrobiana foi observada apenas com a concentração de 5% de vidro bioativo, sendo este grupo estatisticamente diferente do controle (p<0,001). Quando L. acidophilus foi exposto ao polimetilmetacrilato com 5% de vidro bioativo, foi observada diminuição significativa em relação ao grupo controle (p<0,05). Conclusão: A adição de nanopartículas de vidro bioativo nas resinas acrílicas utilizadas na fabricação de aparelhos removíveis revelou um maior efeito antibacteriano contra as bactérias cariogênicas testadas(AU)

Avaliação in vitro de formulações do óleo essencial de citronela (Cymbopogon nardus) sobre propriedades biológicas, físicas e mecânicas de resina acrílica para prótese dentária / In vitro evaluation of citronella (Cymbopogon nardus) essential oil formulations on biological, physical and mechanical properties of acrylic resin for dental prosthesis

O controle de formação de biofilme deve ser promovido por meio de técnicas diárias de higienização, sendo uma delas o uso de soluções de desinfecção. Dentre as soluções químicas comercialmente disponíveis, algumas podem ocasionar efeitos adversos quando utilizadas em longo prazo. Dessa forma, a busca por métodos alternativos de desinfecção, com soluções que não alterem as propriedades do material e que sejam inertes para o seu usuário torna-se essencial. Este estudo teve como objetivos: avaliar in vitro, a ação antifúngica de formulações de 5 mg/mL à base do óleo de citronela em biofilmes mistos de espécie de Candida em resina acrílica ativada termicamente (RAAT) para base protética por meio de contagem do número de unidades formadoras de colônias (UFC/mL), em dois tempos de exposição (15 e 30 minutos) e avaliar a citotoxicidade das formulações em células da linhagem epitelial HaCat, e verificar a ação destas formulações de citronela a 5 mg/mL na alteração de propriedades físicas e mecânicas de amostras de RAAT. Inicialmente, foram feitas as formulações à base de citronela em forma de emulsão e nanoemulsão. Em seguida, por meio de ensaios de microdiluição em caldo, foi obtida a concentração inibitória mínima (CIM) e concentração fungicida mínima (CFM) das cepas de Candida testadas. Foram confeccionadas amostras de RAAT para a realização dos ensaios, sendo 96 amostras para o ensaio de biofilme, divididas de acordo com os grupos: GI - controle negativo (Biofilme misto C. albicans ATCC + C. glabrata ATCC + C. albicans oral 6892 + C. albicans oral 7037); GII- Nanoemulsão de Citronela 5mg/mL; GIIIControle da Nanoemulsão (Tween 20); GIV- Emulsão de Citronela 5mg/mL; GV- Controle da Emulsão (Goma Xantana); GVI- Clorexidina 0,12% (Periogard), e 20 para o ensaio de viabilidade celular, divididas nos grupos: GI- Nanoemulsão de Citronela 5mg/mL; GII- Controle da Nanoemulsão (Tween 20); GIII- Emulsão de Citronela 5mg/mL; GIV- Controle da Emulsão (Goma Xantana); GV- Clorexidina 0,12% (Periogard). Biofilmes mistos de Candida foram formados sobre as superfícies das amostras, e foram quantificados por meio de contagem de unidades formadoras de colônias (UFCs). Para o teste de viabilidade celular utilizou-se células epiteliais da linhagem HaCaT, avaliadas através da coloração com resazurina. Para avaliação das propriedades físicas e mecânicas foram confeccionadas 50 amostras retangulares e 50 circulares de RAAT, separadas aleatoriamente em 5 grupos, de acordo com a formulação utilizada: GI ­ controle (água destilada); GII ­ saliva artificial; GIII ­ nanoemulsão de citronela a 5mg/mL; GIV - emulsão de citronela a 5mg/mL e GV - Clorexidina 0,12% (Periogard). As amostras foram imersas nas respectivas formulações, simulando a desinfecção de próteses dentarias pelo período de 30 minutos diários, durante 6 meses. Após este período, foi feita a análise da alteração de rugosidade de superfície (Ra - µm), estabilidade de cor (CIEDE 2000), avaliação da microdureza Knoop e resistência a flexão (MPa) das amostras. Os dados obtidos foram submetidos às análises estatísticas (p< 0,05). As formulações fitoterápicas à base de citronela apresentaram valores de CIM e CFM que variaram entre 0,156-1 mg/mL sobre as espécies de Candida e inibiram o crescimento do biofilme misto, apresentando uma redução estatisticamente significativa na contagem de UFC/mL, de até 2,7 Log destes fungos, principalmente quando submetidas ao tempo de exposição de 30 minutos. As formulações fitoterápicas testadas não apresentaram diferenças estatísticas entre si, apresentando viabilidade da célula HaCaT maior que 70%, diferentemente da clorexidina a 0,12%. Não houve diferença nos valores médios de rugosidade de superfície em nenhum dos grupos após serem submetidos à imersão nas formulações testes, com exceção do grupo controle, que apresentou diferença estatística significativa na rugosidade de superfície após o período de imersão. Nos valores de alteração de cor (ΔE00) foi possível observar que não houve diferença estatística significativa entre os grupos experimentais antes e após serem submetidos a imersão nas formulações testes. Nos valores de microdureza Knoop houve diferença estatística significativa apenas entre o grupo controle e o grupo emulsão de citronela. Para os dados de resistência flexural, módulo de elasticidade, força máxima e alongamento não houve diferença estatística significativa entre os grupos após imersão. Em suma, concluiu-se que as formulações fitoterápicas à base de citronela apresentaram efeito antifúngico sobre as diferentes espécies de Candida em superfície de resina acrílica para próteses dentárias, não apresentaram efeito citotóxico sobre células da linhagem epitelial, e se mostraram seguras como formulações antissépticas no que se refere às propriedades físicas e mecânicas estudadas, sendo potencialmente promissoras para serem indicadas como soluções desinfetantes para próteses dentárias(AU)

The control of biofilm formation should be promoted through daily hygiene techniques such as the use of disinfection solutions. Among the commercially available chemical solutions, some can lead to adverse effects in long-term use. Thus, the search for alternative methods of disinfection with solutions that do not interfere with properties of the material and those inert to the user becomes essential. This study aimed to: evaluate, in vitro, the antifungal effect of 5 mg/mL formulations based on citronella oil on mixed biofilms of Candida species in thermally activated acrylic resin (TAAR) for prosthetic base by counting the number of colony forming units (CFU/mL), in two exposure times (15 and 30 minutes) and to evaluate the cytotoxicity of the formulations in cells of the HaCat epithelial lineage, and to verify the action of these formulations of citronella at 5 mg/mL in the alteration of physical and mechanical properties of TAAR samples. Initially, citronella-based formulations were prepared as emulsion and nanoemulsion. Then, by means of broth microdilution assays, the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the tested Candida strains were obtained. For the biofilm test, 96 TAAR samples were prepared and assigned to the groups, as follows: GI - negative control (Mixed biofilm C. albicans ATCC + C. glabrata ATCC + C. albicans oral 6892 + C. albicans oral 7037); GII- Citronella Nanoemulsion 5mg/mL; GIII- Nanoemulsion Control (Tween 20); GIV- Citronella Emulsion 5mg/mL; GVEmulsion Control (Xanthan Gum); GVI- Chlorhexidine 0,12% (Periogard). For the cell viability assay, 20 samples were prepared and assigned to the following groups: GI- Citronella Nanoemulsion 5mg/mL; GII- Nanoemulsion Control (Tween 20); GIII- Citronella Emulsion 5mg/mL; GIV- Emulsion Control (Xanthan Gum); GV- Chlorhexidine 0,12% (Periogard). Mixed Candida biofilms were formed on the surfaces of the samples, and were quantified by counting colony forming units (CFUs). For the cell viability test, epithelial cells of the HaCaT lineage were used, evaluated by staining with resazurin. To evaluate the physical and mechanical properties, 50 rectangular and 50 circular samples of TAAR were prepared and randomly assigned into 5 groups, according to the formulation used: GI ­ control (distilled water); GII ­ artificial saliva; GIII ­ citronella nanoemulsion at 5mg/mL; GIV ­ citronella emulsion at 5mg/mL and GV ­ chlorhexidine 0,12% (Periogard). The samples were immersed in the respective formulations, simulating the disinfection of dental prostheses for a period of 30 minutes daily, for 6 months. After this period, the analysis of surface roughness change (Ra - µm), color stability (CIEDE 2000), evaluation of Knoop microhardness and flexural strength (MPa) of the samples was performed. The data obtained were submitted to statistical analysis (p< 0,05). The phytotherapic formulations based on citronella presented MIC and MFC values that varied between 0,156-1 mg/mL on Candida species and inhibited the growth of mixed biofilm, showing a statistically significant reduction in the CFU/mL counts, up to 2,7 Log of these fungi, mainly when subjected to an exposure time of 30 minutes. The phytotherapic formulations tested did not show statistical differences between them, showing HaCaT cell viability greater than 70%, unlike 0,12% chlorhexidine. There was no difference in the mean values of surface roughness in any of the groups after being subjected to immersion in the test formulations, except for the control group, that presented a statistically significant difference in surface roughness after the immersion period. Regarding color change (ΔE00) it was possible to observe that there was no statistically significant difference between the experimental groups before and after being subjected to immersion in the test formulations. In the Knoop microhardness values, there was a statistically significant difference only between the control group and the citronella emulsion group. For data on flexural strength, modulus of elasticity, maximum force and stretching, there was no statistically significant difference between the groups after immersion. In summary, it can be concluded that phytotherapic formulations based on citronella had an antifungal effect on different Candida species on acrylic resin surfaces for dental prostheses, besides not presenting a cytotoxic effect on cells of the epithelial lineage, and proved to be safe as antiseptic formulations in the which refers to the physical and mechanical properties studied, being potentially promising to be indicated as disinfectant solutions for dental prostheses(AU)

Evaluation of biofilm formation on acrylic resin surfaces coated with silicon dioxide: an in situ study

Abstract Biofilm on acrylic resin dental prostheses may cause gingival inflammation. This study evaluated the influence of a silicon dioxide coating layer applied onto acrylic resin on the adhesion of microorganisms. Blocks (5 x 5 x 3 mm) of acrylic resin were evaluated for surface roughness and divided into two groups: control (CG) and coated with silicon dioxide (LG group). The specimens were evaluated by scanning electron microscopy (n = 1) and by contact angle analysis (n = 3). For the in situ study, 20 volunteers wore acrylic palatal devices containing three samples from each group (n = 60) for 2 days. The biofilm formed was quantified by metabolic activity and total biomass using the crystal violet assay. The results were subjected to Bartlett's normality test and Gamma model with random effect for the response variable (α = 5%). The mean contact angle of the coated group was significantly lower than that of the uncoated group (p < 0.05). The metabolic activity of microorganisms in the biofilm on the blocks treated with coating was significantly lower than that of control blocks (p = 0.02). Regarding the amount of extracellular matrix produced by the microorganisms, there was no difference between the CG and LG group (p = 0.05). The application of a silicon dioxide coating on acrylic resin reduced the activity of the polymicrobial biofilm formed in situ. This coating may be advantageous for patients with conventional complete dentures or implants made of acrylic resin and who have motor difficulties that prevent them from cleaning their prostheses properly.

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)

Avaliação qualitativa de dentes artificiais de resina acrílica após escovação simulada / Qualitative evaluation of artificial acrylic resin teeth after simulated brushing

Introdução: os dentes artificiais de resina acrílica são amplamente utilizados na confecção de próteses, por apresentarem propriedades físicas, mecânicas e biológicas, além de características de fácil manuseio. No entanto, devido sua característica de baixa resistência à abrasão, a escovação pode levar à perda de massa dos dentes artificiais e aumento da rugosidade. Objetivo: avaliar de forma qualitativa a rugosidade superficial e polimento de dentes artificiais das marcas Hereaus Premium; Trilux e Vita, após período de 1 ano de escovação, com fotografias em Lupa Estereoscópica. Metodologia: para a realização deste estudo, serão utilizados 10 dentes artificiais de cada marca comercial (Trilux, Vita e Hereaus Premium). Os dentes serão fixados com resina ortoftálica em tubo de PVC de 15 mm de espessura. Para o teste de abrasão, será usada uma máquina de escovação simulada com escovas de dentes de cerdas macias e solução de pasta de dente. As imagens serão obtidas com câmera digital acoplada a lupa estereoscópica. A rugosidade superficial e o polimento serão analisados antes da escovação simulada e após 12 meses de escovação através das imagens. Resultados: após o teste de abrasão foi observado a presença de um desgaste superficial e/ou ranhuras na superfície dos dentes artificiais em todos os grupos. Porém não houve um padrão similar entre os corpos de prova de um mesmo grupo. Conclusão: Pode-se concluir que a escovação provocou o aumento da rugosidade superficial e alteração no polimento em todos os dentes artificiais utilizados.

Introduction: acrylic resin artificial teeth are widely used in the manufacture of dentures, as they have physical, mechanical and biological properties, in addition to easy handling characteristics. However, due to its characteristic of low abrasion resistance, brushing can lead to loss of mass of artificial teeth and increase in roughness. Objective: qualitatively evaluate the surface roughness and polishing of artificial teeth of Hereaus Premium brands; Trilux and Vita, after a 1-year brushing period, with photographs using a Stereoscopic Magnifying Glass. Methodology: for this study, 10 artificial teeth of each commercial brand will be used (Trilux, Vita and Hereaus Premium). Teeth will be fixed with orthophthalic resin in a 15 mm thick PVC tube. For the abrasion test, a simulated brushing machine with soft bristle toothbrushes and toothpaste solution will be used. Images will be obtained with a digital camera coupled to a stereoscopic magnifying glass. Surface roughness and polishing will be analyzed before simulated brushing and after 12 months of brushing through the images. Results: after the abrasion test, the presence of surface wear and/ or grooves on the surface of the artificial teeth was observed in all groups. However, there was no similar pattern between the specimens of the same group. Conclusion: it can be concluded that brushing caused an increase in surface roughness and change in polishing in all artificial teeth used.

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)

Efecto de la exposición a bebidas carbonatadas en la dureza superficial de resinas acrílicas / Effect of Exposure to Carbonated Beverages on the Surface Hardness of Acrylic Resins

ABSTRACT: The purpose of this study was to evaluate and compare the effect of carbonated beverage on the surface microhardness of two acrylic materials used to fabricate temporary restorations. The study was experimental in vitro. Forty blocks of acrylic resins used in provisional restorations were made, 20 from Alike® (GC AMERICA INC., Lot 1712161) and 20 from Acryptemp® (Zhermack S.P.A., Lot 302334). After that, the blocks were immersed in distilled water for 24 hours. After this time, the initial surface microhardness was measured. Then the 20 samples of the experimental group were immersed in a carbonated drink (coca cola - soda) for 12 minutes per day, for 5 days. Finally, the final surface microhardness was measured using the Vickers microdurometer. Measures of central tendency and dispersion were used, and the Student's t test and ANOVA were performed. A mean surface microhardness of 8.8 and 7.2HV was found for the PMMA resin group (Initial and final respectively), and 9.5 and 8HV for the bisacrylate group. Statistically significant differences were found when comparing the beginning and end of each group and when comparing the two materials. The acrylic resin of polymethylmethacrylate (Alike® GC AMERICA INC.) Presented higher surface microhardness compared to the bis acrylic resin (Acrytemp® Zhermack S.P.A), after being exposed to a carbonated drink.

RESUMEN: El propósito de este estudio fue evaluar y comparar el efecto de la bebida carbonatada en la microdureza superficial de dos materiales acrílicos utilizados para confeccionar restauraciones provisionales. El estudio fue experimental in vitro. Se confeccionaron 40 bloques de resinas acrílicas utilizadas en provisorios, 20 de Alike® (GC AMERICA INC., Lote 1712161) y 20 de Acryptemp® (Zhermack S.P.A., Lote 302334). Posterior a ello, se sumergió los bloques en agua destilada por 24 horas. Pasado este tiempo se procedió a medir la microdureza superficial inicial. Luego las 20 muestras del grupo experimental se sumergieron en una bebida carbonatada (coca cola-gaseosa) durante 12 minutos por día, durante 5 días. Por último se midió la microdureza superficial final mediante el microdurómetro de Vickers. Se utilizaron medidas de tendencia central, dispersión y se realizaron la prueba t de Student y ANOVA. Se encontró una microdureza superficial media de 8,8 y 7,2HV para el grupo de resina PMMA (Inicial y final respectivamente), y 9,5 y 8HV para el grupo de bisacrilato. Se halló diferencias estadísticamente significativas al comparar el inicio y final de cada grupo y al comparar los dos materiales. La resina acrílica de polimetilmetacrilato (Alike® GC AMERICA INC.) presentó mayor microdureza superficial en comparación con la resina bis acrílica (Acrytemp® Zhermack S.P.A), después de ser expuestas a una bebida carbonatada.

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)

Resistencia al impacto de dos acrílicos convencionales y dos de alto impacto para prótesis total / Impact resistance of two conventional and two high impact acrylics for dentures / Resistência ao impacto de dois acrílicos convencionais e dois acrílicos de alto impacto para próteses totais

Resumen Introducción y objetivo: las resinas acrílicas son los materiales idóneos para la elaboración prótesis totales, sin embargo, las caídas o golpes los hace susceptibles de fracturas. Conocer las propiedades y limitaciones de los acrílicos en nuestro entorno, nos permite realizar tratamientos con los mejores materiales. El objetivo de este estudio fue comparar la resistencia al impacto de dos acrílicos convencionales y dos de alto impacto para bases protésicas. Materiales y métodos: se realizaron 40 barras en cera para base para ser enmufladas de acuerdo con especificaciones de cuatro marcas de acrílicos (n=10), Lucitone199®, Masterdent acrylic resin, Veracril alto impacto® y convencional. La resistencia impacto se evaluó mediante la prueba de Charpy (Máquina ITC-XJU-22), con masa de péndulo de 0.237 Kg y fuerza de impacto de 1J. se realizó análisis estadístico por ANOVA a una vía y prueba de tukey. Resultados: los valores de resistencia al impacto fueron 16.5, 10.8, 9.3 y 5.9 KJ/m2 para Lucitone199®, Veracril alto impacto®, Veracril convencional® y Masterdent acrylic resin. Conclusiones: con las limitaciones de esta investigación, los acrílicos de alto impacto se pueden considerar como una alternativa más viable para la elaboración de prótesis totales ante los acrílicos convencionales, en busca de disminuir el riesgo de fracturas por accidentes o cargas repentinas de impacto.

Abstract Introduction and objective: acrylic resins are the ideal materials for the elaboration of dentures and removable prostheses, although the falls or blows make them susceptible to fractures. Knowing the properties and limitations of acrylics in our environment, allows us to carry out treatments with the best materials. The objective of this study was to compare the impact resistance of two conventional and two high impact acrylics for prosthetic bases. Materials and methods: 40 bars were made in base-wax and processed in muffles according to specifications of four trademarks of acrylics (n=10), Lucitone199®, Masterdent acrylic resin®, Veracril alto impacto® and convencional®. The impact resistance was evaluated by the Charpy test (Machine ITC-XJU-22), with a pendulum mass of 0.237 Kg and an impact force of 1J. One-way ANOVA and tukey test were performed for statistical analysis was performed. Results: the impact resistance values were 16.5, 10.8, 9.3 and 5.9 KJ / m2 for Lucitone199®, Veracril alto impacto®, Veracril convencional® and Masterdent acrylic resin®. Conclusions: with the limitations of this investigation, high impact acrylics can be considered as a more viable alternative for the elaboration of dentures compared to conventional acrylics, in order to reduce the risk of fractures due to accidents or sudden impact loads.

Resumo Introdução y objetivo: as resinas acrílicas são os materiais ideais para a elaboração de próteses totais, porém as quedas ou golpes os tornam suscetíveis a fraturas. Conhecer as propriedades e limitações dos acrílicos em nosso ambiente, permite realizar tratamentos com os melhores materiais.. O objetivo deste estudo foi comparar a resistência ao impacto de d ois acrílicos convencionais e dois de alto impacto para bases protéticas. Materiais e métodos: foram feitas 40 barras de cera para que a base seja silenciada de acordo com as especificações de quatro marcas de acrílicos (n=10), Lucitone199®, resina acrílica Masterdent, Veracril high impact® e convencional. A resistência ao impacto foi avaliada pelo teste de Charpy (Máquina ITC-XJU-22), com uma massa pendular de 0.237 kg e uma força de impacto de 1J. Foi realizada análise estatística ANOVA unidirecional e teste de tukey. Resultados: os valores de resistência ao impacto foram de 16.5, 10.8, 9.3 e 5.9 KJ/m2 para a resina acrílica Lucitone199®, Veracril high impact®, Veracril convencional® e Masterdent. Conclusões: com as limitações desta investigação, os acrílicos de alto impacto podem ser considerados uma alternativa mais viável para a elaboração de próteses totais em comparação aos acrílicos convencionais, a fim de reduzir o risco de fraturas devido a acidentes ou cargas de impacto repentinas.