Effect of incorporation of 2-tert-butylaminoethyl methacrylate on flexural strength of a denture base acrylic resin

Polymethyl methacrylate (PMMA) resins have commonly been used as a denture base material. However, denture bases may act as a reservoir for microorganisms and contribute to oral diseases in denture wearers. It is hypothesized that the 2-tert-butylaminoethyl methacrylate (TBAEMA) incorporated to acrylic resins should have antimicrobial activity related to the presence of amino groups on acrylic resin surface. OBJECTIVES: The objectives of this study were to evaluate the presence of amino groups on acrylic resin surface and the influence on flexural strength after incorporation of TBAEMA. MATERIAL AND METHODS: Six groups were divided according to the concentration of TBAEMA incorporated to acrylic resin (Lucitone 550): 0, 0.5, 1.0, 1.5, 1.75 and 2%. Specimens surface were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA) to detect the presence of amino groups, represented by nitrogen ratios. Flexural strength of the specimens was tested and results were analyzed by ANOVA and Tukey's test (α=0.05). RESULTS: Different nitrogen ratios were observed on specimen surfaces: 0, 0.13, 0.74, 0.66, 0.92 and 0.33% for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively. Significant differences were found for flexural strength (

Effect of an acrylic resin combined with an antimicrobial polymer on biofilm formation

OBJECTIVES: The purpose of this study was to evaluate the antimicrobial activity of an acrylic resin combined with an antimicrobial polymer poly (2-tert-butylaminoethyl) methacrylate (PTBAEMA) to inhibit Staphylococcus aureus, Streptococcus mutans and Candida albicans biofilm formation. MATERIAL AND METHODS: Discs of a heat-polymerized acrylic resin were produced and divided according to PTBAEMA concentration: 0 (control), 10 and 25%. The specimens were inoculated (10(7) CFU/mL) and incubated at 37ºC for 48 h. After incubation, the wells were washed and each specimen was sonicated for 20 min. Replicate aliquots of resultant suspensions were plated at dilutions at 37ºC for 48 h. The number of colony-forming units (CFU) was counted and expressed as log (CFU+1)/mL and analyzed statistically with α=.05. RESULTS: The results showed that 25% PTBAEMA completely inhibited S. aureus and S. mutans biofilm formation. A significant reduction of log (CFU+1)/mL in count of S. aureus (control: 7.9±0.8A; 10%: 3.8±3.3B) and S. mutans (control: 7.5±0.7A; 10%: 5.1±2.7B) was observed for the group containing 10% PTBAEMA (Mann-Whitney,

One-year prospective clinical study comparing patient satisfaction and masticatory performance of mandibular overdentures supported by one versus two implants

There is a lack of clinical evidence on mandibular overdentures (MOD) supported by a single implant. Objective: To compare patient satisfaction and masticatory performance in MOD supported by one versus two implants in a two-group parallel randomized clinical trial. Material and Methods:Twenty-one patients wearing new maxillary and mandibular complete dentures (CDs) were randomly divided to receive one (GI, n = 11) or two (GII, n = 10) implants in the mandibular arch. Four months after implant placement, o-ring abutments were installed in the implants, and matrix attachments were placed in the lower complete dentures. Patient satisfaction with their dentures and masticatory performance were compared at baseline, 3, 6, and 12 months after the procedure. Data on patient satisfaction were analyzed using the Friedman test and the Mann-Whitney U test. Data on masticatory performance were analyzed using one-way repeated measures analysis of variance (ANOVA) and Student's t test (α=0.05). Results: Both groups exhibited a significant increase in overall patient satisfaction in all periods evaluated (p<0.05), except for GI after 12 months, which had values similar to baseline (p=0.74). Satisfaction levels of GI and GII were similar at baseline, 3 and 6 months, but GII showed higher satisfaction levels (p=0.01) than GI at 12 months. GI and GII exhibited a significant increase (p<0.05) in masticatory performance for all periods relative to baseline. However, GII had higher masticatory performance with dentures than GI, regardless of the period (p<0.05). Conclusion: MOD supported by two implants demonstrated better patient satisfaction in the follow-up at 12 months and better masticatory performance than MOD supported by one implant. &nbsp

Evaluation of quality of life, sleep, and sleepiness in dental students during active learning and remote emergency learning

Objective: This study aimed to evaluate the quality of life (QoL), quality of sleep, and sleepiness index in undergraduate dentistry students between their active learning (AL) and emergency remote learning (ERL) due to social distancing imposed during the COVID-19 pandemic. Methods: Information was collected using the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36-BR), Epworth Sleepiness Scale (ESS-BR), and Pittsburgh Sleep Quality Index (PSQI-BR) questionnaires administered before and during the COVID-19 pandemic. A comparison regarding the type of education, demographic factors, academic performance, PSQI-BR, ESS-BR, and SF-36-BR between the groups was performed, considering a significance level of 0.05. Results: A total of 55 students were from AL, while 45 students were from ERL. The sample consisted of 74 women and 26 men aged 21–30 years. The academic coefficient of these students ranged from 7 to 8 points (AL= 38.2% and ERL= 57.8%).  In addition, a large proportion of the students reported having no failures (AL=60% and ERL= 66.7%). Regarding QoL, the students presented a greater impairment in functional capacity (p = 0.01), followed by limitations in social aspects, general health perception, body pain, and vitality. According to the ESS-BR scores (p = 0.04), the students presented a lower quality of sleep. Conclusion: Dentistry students had the worst QoL panoramas and poor relative sleep quality before and during the COVID-19 pandemic. Furthermore, QoL instruments were reliable for quantifying health-related QoL in AL and ERL.

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Incorporação do metacrilato 2-tert-butilaminoetil a uma resina acrílica para a base protética: caracterização química e efeito sobre a resistência flexural

A fim de prevenir infecções bucais e consequentemente melhorar a qualidade de vida dos usuários de prótese, diversas tentativas de incorporar agentes antimicrobianos a resinas acrílicas tem sido relatadas na literatura. A incorporação do metacrilato 2-tert-butilaminoetil (TBAEMA) a uma resina acrílica para base protética seria uma alternativa plausível no intuito de se reduzir ou eliminar a colonização dessa superfície por microrganismos patogênicos, pois esta substância apresenta grupos amina em sua composição, o que poderia indicar uma possível atividade antimicrobiana da base protética. Objetivo: O objetivo deste trabalho foi investigar a interação química entre o TBAEMA e a resina acrílica bem como a presença de grupos amina na superfície da resina, e ainda avaliar a temperatura de transição vítrea e a resistência à flexão da resina após a incorporação de TBAEMA. Material e método: Os espécimes foram divididos em cinco grupos de acordo com as concentrações de TBAEMA incorporadas à resina Onda-Cryl: 0%, 1%, 2%, 3% e 4%. A superfície dos espécimes foi avaliada por meio de Espalhamento Superficial de Elétrons com Análise Química (XPS-ESCA) para detectar a presença de grupos amina, representado por índices de nitrogênio. As análises de Espectroscopia de Infravermelho por Transformada de Fourier (FTIR) e Calorimetria Diferencial de Varredura (DSC) foram utilizadas para avaliar o processo de polimerização da resina 17 acrílica na presença do TBAEMA e a influência da incorporação do TBAEMA na temperatura de transição vítrea (Tg) da resina, respectivamente. A resistência à flexão dos espécimes também foi avaliada e os resultados foram analisados por meio de análise de variância a um fator (ANOVA) seguido pelo teste de Tukey ( <0.05). Resultados: Foram observados diferentes índices de nitrogênio: 0,36%, 0,54%, 0,35% e 0,20% para...With a purpose of to prevent oral infections and therefore improve the quality of life of dentures wearers, several attempts to incorporate antimicrobial agents into acrylic resins have been reported in the literature. The incorporation of 2-tert-butylaminoethyl methacrylate (TBAEMA) into denture base acrylic resin would be a plausible alternative in order to reduce or eliminate colonization of that surface by pathogenic microorganisms, on this account this substance has amine groups in their composition, which could indicate a possible antimicrobial activity of the denture base. Purpose: The purpose of this study was to investigate the chemical interaction between the TBAEMA and acrylic resin and the presence of amine groups in the resin surface, and assess the glass transition temperature and flexural strength of the resin after the incorporation TBAEMA. Material and Method: The specimens were divided in five groups according to the concentration of TBAEMA incorporated to Onda-Cryl: 0%, 1%, 2%, 3% and 4%. Specimens surfaces were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA) to detect the presence of amino groups, represented by nitrogen ratios. Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) analysis were used to evaluate the polymerization process of acrylic resin in the presence of TBAEMA and the influence of the incorporation of TBAEMA on the glass transition temperature (Tg) of acrylic resin, respectively. Flexural strength of the... (Complete abstract click electronic access below)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Effect of incorporation of 2-tert-butylaminoethyl methacrylate on flexural strength of a denture base acrylic resin

Polymethyl methacrylate (PMMA) resins have commonly been used as a denture base material. However, denture bases may act as a reservoir for microorganisms and contribute to oral diseases in denture wearers. It is hypothesized that the 2-tert-butylaminoethyl methacrylate (TBAEMA) incorporated to acrylic resins should have antimicrobial activity related to the presence of amino groups on acrylic resin surface. Objectives: The objectives of this study were to evaluate the presence of amino groups on acrylic resin surface and the influence on flexural strength after incorporation of TBAEMA. Material and Methods: Six groups were divided according to the concentration of TBAEMA incorporated to acrylic resin (Lucitone 550): 0, 0.5, 1.0, 1.5, 1.75 and 2%. Specimens surface were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA) to detect the presence of amino groups, represented by nitrogen ratios. Flexural strength of the specimens was tested and results were analyzed by ANOVA and Tukey's test (alpha=0.05). Results: Different nitrogen ratios were observed on specimen surfaces: 0, 0.13, 0.74, 0.66, 0.92 and 0.33% for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively. Significant differences were found for flexural strength (p<0.001). The mean flexural strength values were 98.3 +/- 3.9, 93.3 +/- 3.2, 83.9 +/- 2.1, 82.8 +/- 5.2, 71.2 +/- 5.1 and 17.3 +/- 3.2 MPa for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively. Conclusion: Within the limitations of this study, the incorporation of TBAEMA results in the presence of the potentially antimicrobial amino groups on specimen surfaces, but affect the flexural strength, depending on the concentration of TBAEMA.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP