Action of chitosan-based solutions against a model four-species biofilm formed on cobalt-chromium and acrylic resin surfaces.

OBJECTIVE: To evaluate the anti-biofilm action of chitosan, nanoparticulate chitosan, and denture cleanser Nitradine™ against biofilms comprising Candida albicans, Candida glabrata, Staphylococcus aureus, and Streptococcus mutans. BACKGROUND: Biofilm removal from removable partial dentures (RPD) is important for success in prosthetic rehabilitation. MATERIALS AND METHODS: The anti-biofilm action of the experimental chitosan-based solutions and Nitradine™ was evaluated on acrylic resin and cobalt-chromium alloy through assessing cell viability, cell metabolism, residual aggregated biofilm, and extracellular polymeric substance and biofilm morphology. RESULTS: Only chitosan reduced the viability of C. albicans on cobalt-chromium alloy surface, by 98% (a 1.7 log10 reduction in cfu). Chitosan-based solutions neither promoted substantial alteration of the metabolic activity of the four-species biofilm nor reduced the amount of the aggregated biofilm. After immersion in chitosan and nanoparticulate chitosan, viable microorganisms and extracellular polymeric substances distributed over the entire specimens' surfaces were observed. Nitradine™ reduced the viability and metabolic activity of biofilm grown on both surfaces, but it did not remove all aggregated biofilm and extracellular polymeric substances. After immersion in Nitradine™, approximately 35% of the specimens' surfaces remained covered by aggregated biofilm, mainly composed of dead cells. CONCLUSION: Although chitosan and Nitradine™ promoted changes in the viability of microorganisms, neither solution completely removed the four-species biofilm from the Co-Cr and acrylic resin surfaces. Thus, isolated use of hygiene solutions is not indicated for biofilm control on RPDs; this requires complementary mechanical removal.

Effect of Cleanser Solutions on the Retention Force of O'ring Attachment: An in Vitro Study.

The aim of this study was to evaluate the effect of cleaning solutions on the retention force of o-ring-type overdenture attachments. The effect of four solutions on nitrile rings were evaluated: Cepacol (C), Cepacol with fluoride (CF), Listerine (L) and 0.05% sodium hypochlorite (SH); deionized water (DW) was used as a control. Matrices containing two implants and abutments and acrylic specimens with the metal capsules were obtained and divided into the groups. A simulation of 90 overnight immersions (8 h) was performed, and the tensile strength value was obtained at the beginning (T0) and in every 30 days (T1, T2 and T3) (n=6). In order to analyze o-ring surface damage after the immersions, a scanning electron microscopy (SEM) was used (n=1). For statistical analysis of the results, analysis of variance (ANOVA) and multiple comparisons with Bonferroni adjustment (test power=1.000; a=0.05) were used. There was a significant difference for the factors time (p<0.001), solution (p<0.001) and for the interaction time × solution (p<0.001). Considering the times of each solution, only for DW there was no significant loss of retention over time. Comparing the solutions in each moment, there was no difference among the solutions in T0. From T1, CF and SH provided less retention than DW (p<0.005). Through SEM it was possible to observe changes in the surface of the CF and SH nitrile o-rings. CF and SH should be avoided due to deleterious action in o-rings.

Effect of cleanser solutions on the retention force of oring attachment: an in vitro study

Abstract The aim of this study was to evaluate the effect of cleaning solutions on the retention force of o-ring-type overdenture attachments. The effect of four solutions on nitrile rings were evaluated: Cepacol (C), Cepacol with fluoride (CF), Listerine (L) and 0.05% sodium hypochlorite (SH); deionized water (DW) was used as a control. Matrices containing two implants and abutments and acrylic specimens with the metal capsules were obtained and divided into the groups. A simulation of 90 overnight immersions (8 h) was performed, and the tensile strength value was obtained at the beginning (T0) and in every 30 days (T1, T2 and T3) (n=6). In order to analyze o-ring surface damage after the immersions, a scanning electron microscopy (SEM) was used (n=1). For statistical analysis of the results, analysis of variance (ANOVA) and multiple comparisons with Bonferroni adjustment (test power=1.000; a=0.05) were used. There was a significant difference for the factors time (p<0.001), solution (p<0.001) and for the interaction time × solution (p<0.001). Considering the times of each solution, only for DW there was no significant loss of retention over time. Comparing the solutions in each moment, there was no difference among the solutions in T0. From T1, CF and SH provided less retention than DW (p<0.005). Through SEM it was possible to observe changes in the surface of the CF and SH nitrile o-rings. CF and SH should be avoided due to deleterious action in o-rings.

Resumo O objetivo do estudo foi avaliar o efeito de soluções higienizadoras sobre a força de retenção de encaixes do tipo o-ring. Foram avaliadas quatro soluções: Cepacol (C); Cepacol com flúor (CF), Listerine (L), hipoclorito de sódio 0,05% (HS) e água deionizada (controle/AD) em o-rings de nitrilo. Matrizes contendo dois implantes e pilares e espécimes em acrílico com as cápsulas metálicas foram obtidas e divididas entre os grupos. Foi realizada a simulação de 90 imersões noturnas (8 h), sendo obtido o valor da resistência à tração no início e a cada 30 dias (T0, T1, T2 e T3) por meio da máquina de ensaios mecânicos (n=6). Microscopia eletrônica de varredura (MEV) foi utilizada para análise de danos na superfície do o´ring após a imersão (n=1). Para análise estatística dos resultados foi utilizada análise de variância (ANOVA) e múltiplas comparações com ajuste de Bonferroni (poder do teste=1,000; a=0,05). Houve diferença significante para os fatores tempo (p<0,001), solução (p<0,001) e para interação de tempo × solução (p<0,001). Considerando-se os tempos de cada solução, apenas AD não apresentou perda significativa de retenção ao longo do tempo. Comparando as soluções em cada momento, não houve diferença entre as soluções em T0. A partir de T1, CF e HS propiciaram menor retenção quando comparados à AD (p <0,005). Através do MEV foi possível observar alterações nas superfícies dos o-rings de nitrilo imersos em CF e HS. O Cepacol com flúor e hipoclorito de sódio devem ser evitados devido à ação deletéria nos o-rings.

In Vitro Antimicrobial Activity of Effervescent Denture Tablets on the Components of Removable Partial Dentures.

PURPOSE: To evaluate the antimicrobial activity of effervescent tablets on the surfaces of cobalt-chromium (Co-Cr) and heat-polymerized resin. MATERIALS AND METHODS: From a metal matrix, 55 circular wax patterns (Ø 12 × 3 mm) were obtained and cast in Co-Cr alloy. Muffles for acrylic resin were prepared from circular wax patterns (Ø 20 × 5 mm). The metal specimens were positioned in the muffle, and the resin was pressed into its surroundings to simulate the composition of a removable partial denture (RPD). The mixed specimens were sterilized and contaminated with Streptococcus mutans, Staphylococcus aureus, Candida albicans, and Candida glabrata, composing a multispecies biofilm, and subsequently immersed according to the manufacturer's instructions in four cleansing solutions: Polident 3 Minute denture cleanser (P3M), Polident for Partials (PP), Corega Tabs (CT), and NitrAdine (Ni); as well as distilled water (positive control) and no contamination (negative control). After cleansing, viable microorganisms were quantified by counting the number of colony-forming units (CFU/mL). From the CFU values, log10(CFU + 1) values were calculated for statistical analysis. Kruskal-Wallis test with Dunn post hoc test were performed (α = .05). RESULTS: There was a significant reduction (P = .001) of S mutans after immersion in Ni (median [95% CI] 3.27 [2.92; 3.45]) compared to the CT (3.86 [3.75; 4.01]) and control (4.08 (3.73; 4.22]) groups, while the PP (3.63 [3.28; 4.11]) and P3M (3.83 [3.61; 4.04]) groups presented an intermediate action. The effervescent tablets did not present antimicrobial action against S aureus (P = .537), C albicans (P = .795), or C glabrata (P = .519). CONCLUSION: Ni exhibited moderate antimicrobial action. The effervescent tablets did not promote reduction of multispecies biofilm, and their daily use should be carefully considered.

Effect of Denture Cleansers on Cobalt-Chromium Alloy Surface: A Simulated Period of 5 Years' Use.

PURPOSE: To compare the effect of solutions of effervescent tablets (ET), cetylpyridinium chloride (CPC), and experimental solutions of Ricinus communis on the surface of cobalt-chromium (Co-Cr) alloys. MATERIALS AND METHODS: Fifty-five specimens of Co-Cr were prepared by the lost-wax casting method using circular patterns (∅12 × 3 mm). The specimens were randomly divided into 5 groups: deionized water (control); 2% R. communis; 10% R. communis; ET, and CPC. The surface roughness of specimens (n = 10) was evaluated before immersion (baseline), and at simulated times of ½, 1, 2, 3, 4, and 5 years, by laser confocal microscope (Sa, µm) and profilometer (Ra, µm). The surface topography and chemical composition (n = 1) was qualitatively analyzed with scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS). Data were subjected to Kruskal-Wallis followed by Dunn tests, and Friedman followed by Wilcoxon tests (α = 0.05). RESULTS: For Sa, there was no difference for the solution factor. For the time factor a significant difference was found with 2% R. communis solution among baseline and ½, 2, 3, and 5 years (p < 0.001) and with 10% R. communis solution between 1 and 2 years (p = 0.007), with decreasing roughness over time. For Ra, cetylpyridinium chloride exhibited less roughness than 10% R. communis solution in ½ (p = 0.048) and 5 years (p = 0.013). In the SEM and EDS analysis the solutions did not present deleterious effects or changes in the chemical composition on the surfaces. CONCLUSIONS: Although a significant difference was found for the roughness, the results, below 0.2 µm, are clinically acceptable. Thus, all solutions can be used safely in removable partial denture cleaning for a period of 5 years.

Effect of Alkaline Peroxides on the Surface of Cobalt Chrome Alloy: An In Vitro Study.

PURPOSE: Removable denture hygiene care is very important for the longevity of the rehabilitation treatment; however, it is necessary to analyze the effects that denture cleansers can cause on the surfaces of prostheses. Thus, this study evaluated the effect of alkaline peroxide-effervescent tablets on the surface of cobalt-chromium alloys (Co-Cr) used in removable partial dentures. MATERIALS AND METHODS: Circular metallic specimens (12 × 3 mm) were fabricated and were immersed (n = 16) in: control, Polident 3 Minute (P3M), Steradent (S), Efferdent (E), Polident for Partials (PFP), and Corega Tabs (CT). The surface roughness (µm) (n = 10) was measured before and after periods of cleanser immersion corresponding to 0.5, 1, 2, 3, 4, and 5 years. Ion release was analyzed (n = 5) for Co, Cr, and molybdenum (Mo). Scanning electron microscopy (SEM) analysis and an Energy-dispersive X-ray spectroscopy (EDS) were conducted in one specimen. The surface roughness data were statistically analyzed (α = 0.05) with the Kruskal-Wallis test to compare the solutions, and the Friedman test compared the immersion durations. Ion release analysis was performed using 2-way ANOVA and Tukey's test. RESULTS: There was no significant surface roughness difference when comparing the solutions (p > 0.05) and the immersion durations (p = 0.137). Regarding ion release (µg/L), CT, E, and control produced a greater release of Co ions than S (p < 0.05). CT produced a greater release of Cr ions than control, S, and P3M (p < 0.05). Finally, E caused the greatest release of Mo ions (p < 0.05). SEM confirmed that the solutions did not damage the surfaces and EDS confirmed that there were no signs of oxidation. CONCLUSION: The various solutions tested did not have any deleterious effects on the Co-Cr alloy surface. Steradent, however, presented the smallest ionic release.

Avaliação do conhecimento de professores sobre avulsão dentária / Evaluation of teachers's knowlwdge concerning tooth avulsion

Objetivo: Avaliar o conhecimento de professores do ensino fundamental sobre as condutas nos casos de avulsão dentária em escolares. Materiais e Métodos: O estudo descritivo foi realizado em uma amostra de conveniência com 52 professores, de quatro escolas de ensino fundamental em Ribeirão Preto, SP, e queresponderam a um questionário com perguntas sobre os seus dados pessoais e os conhecimentos sobre aavulsão dentária. Resultados: Os participantes do estudo tinham, em média, 41 (±9,4) anos de idade, e 96,2% eram do gênero feminino. Sobre os procedimentos a tomar em caso de avulsão dentária, 73,1% disseram quenão os conheciam, 40,4% já haviam testemunhado uma avulsão no ambiente escolar, no entanto, apenas 23,5%tentariam fazer o reimplante. Recolheriam o dente avulsionado e levariam a criança e o dente ao dentista para o diagnóstico correto, 34,6% dos participantes, contudo, apenas 9,6% deixariam o dente menos de 1 hora fora da cavidade bucal. Material seco (gaze, jarra de vidro, algodão) foi a escolha de 42,6% dos entrevistadospara transportar o dente ao dentista, enquanto a água e o leite tiveram menor percentual de resposta (13,1%).Conclusão: O conhecimento dos professores sobre as condutas mais apropriadas a serem tomadas frente àavulsão dentária é inadequado e a maior capacitação desses profissionais poderia levar ao correto tratamentoe ao melhor prognóstico.