Microbiological evaluation for antifungal activity of some metal oxides nanofillers incorporated into cold cured soft lining materials: clinical based study / Avaliação microbiológica da atividade antifúngica de algumas nanopartículas de óxidos metálicos incorporadas em materiais de revestimento macio curados a frio: estudo clínico

Objetivo: O objetivo do presente estudo foi avaliar a eficácia da adição de nanopartículas de óxido de zircônio (ZrO2), óxido de titânio (TiO2) e óxido de sílica (SiO2) a um material de revestimento macio curado a frio na adesão de Candida albicans (CA). Material e Método: Cinquenta e quatro pacientes foram selecionados e divididos em três grupos de acordo com a modificação do revestimento com nanopartículas de ZrO2, TiO2 e SiO2 (18 cada). Cada paciente recebeu prótese total maxilar com três cavidades, as cavidades foram revestidas com forro macio curado a frio modificado com diferentes concentrações (0%, 3% e 7%) de nanopartículas de óxido metálico. Nos dias 14 e 28, as trocas foram retiradas do local de realinhamento e imediatamente cultivadas para avaliação fúngica. O número de colônias foi contado, os dados coletados e explorados para normalidade usando o teste de Shapiro-Wilk e a transformação logarítmica da contagem de CA foi realizada. ANOVA para medidas repetidas e de uma via (one-way) foram usados, seguidos por teste de Tukey (HSD). O teste t independente foi usado para comparar as contagens de CA em diferentes períodos. Resultados: A adesão do CA foi significativamente diminuída pela adição de nanopartículas de ZrO2, TiO2 e SiO2 em comparação com o grupo controle, também a cobertura antifúngica aumentou com o aumento da concentração de nanopartículas (p <0,005). A maior contagem de CA foi identificada no grupo SiO2 seguido por ZrO2, enquanto TiO2apresentou a menor contagem de CA (p <0,001). Conclusão: Adição de diferentes nanopartículas; ZrO2, TiO2 e SiO2para revestimento macio curado a frio é um método eficaz para reduzir a adesão de CA (AU)

Objective: The aim of the current study was to evaluate the efficacy of addition of zirconium oxide (ZrO2), titanium oxide (TiO2), and silica oxide (SiO2) nanoparticles to cold-cured soft liner on adhesion of Candida albicans (CA). Material and Methods: Fifty-four patients had been selected and divided into three groups according to the modification of soft liner with ZrO2, TiO2, and SiO2 nanoparticles (18 each of). Each patient received maxillary complete denture having three cavities, the cavities were lined using cold cured soft liner modified with different concentration (0%, 3%, and 7%) of metal oxide nanoparticles. On days 14 and 28, swaps were taken out from relining site and immediately cultured for fungal evaluation. The number of colonies were counted, data collected and explored for normality using Shapiro-Wilk test, logarithmic transformation of CA count was performed. Repeated and one-way ANOVA were used followed by Tukey HSD. Independent-t test used to compare between CA counts at different periods. Results: The CA adhesion was significantly decreased by the addition of ZrO2, TiO2 and SiO2 nanoparticles in comparison with control group, also the antifungal coverage increased with nanoparticles concentration increased (P<0.005). The highest CA count was identified in group SiO2 followed by ZrO2, while TiO2 showed the lowest CA count (P <0.001). Conclusion: Addition of different nanoparticles; ZrO2, TiO2 and SiO2 to cold-cured soft liner is an effective method for reducing CA adhesion. (AU)

Estimation of the autoclave and different surface treatments on microleakage between soft liner and heat-cured acrylic / Estimativa da autoclavagem e diferentes tratamentos de superfície na microinfiltração entre o soft liner e o acrílico termopolimerizável

Objective: The present study was oriented to estimate the effect of different surface treatments on the microleakage between the soft liner and acrylic with and without the use of autoclave as disinfection method. Material and Methods: Sixty samples were split into two groups: the autoclaved groups and non-autoclaved groups. Each one subdivided into three groups: first one without any treatments as a control group; in the second group surface of the samples were treated with CO2 laser (10.6 nm wavelength for 15 seconds), and in the third group the surface was treated with sandblasting (250 µm Al2O3). All the samples exposed to thermocycling, then the microleakage test was evaluated by gauging dye penetration depth between the soft liner and acrylic disc using a digital microscope. Data analyzed statistically by One-way ANOVA and Tukey's post-hoc tests. In addition, t-test was used for comparison between two groups (P-value ≤ 0.05). Results: The maximum mean values for the microleakage were observed in the untreated group (control) followed by the group treated by CO2 laser and the lowest mean value of microleakage was related to the third group for both non-autoclaved and autoclaved groups with significant differences among them. In addition, depending on the use of autoclave, there was non-significant in all studied groups. Conclusions: There was a decrease in the microleakage when the surface treated with CO2laser and sandblast. The use of autoclave did not badly change the microleakage between the soft liner and denture base. (AU)

Objetivo: O presente estudo teve como objetivo estimar o efeito de diferentes tratamentos de superfície na microinfiltração entre o soft liner e o acrílico usando ou não a autoclve como método de desinfecção. Material e Métodos: Sessenta amostras foram divididas em dois grupos: grupo com uso da autoclave e grupo sem uso da autoclave. Cada um subdivide em três grupos: o primeiro sem nenhum tratamento como grupo controle; no segundo grupo, a superfície das amostras foi tratada com laser de CO2 (comprimento de onda de 10,6 nm por 15 segundos) e, no terceiro grupo, a superfície foi tratada com jateamento (250 µm Al2O3). Todas as amostras foram expostas à termociclagem, em seguida o teste de microinfiltração foi realizado medindo-se a profundidade de penetração do corante entre o soft liner e o disco de acrílico em microscópio digital. Os dados foram analisados estatisticamente por One-way ANOVA e testes post-hoc de Tukey. Além disso, o teste t foi usado para comparação entre dois grupos (P-valor ≤ 0,05). Resultados: Os valores médios máximos de microinfiltração foram observados no grupo não tratado (controle) seguido pelo grupo tratado com laser de CO2 e o valor médio mínimo de microinfiltração foi relacionado ao terceiro grupo para ambos os grupos não autoclavado e autoclavado com diferenças significativas entre eles. Além disso, dependendo do uso de autoclave, não houve significância em todos os grupos estudados. Conclusão: Houve diminuição da microinfiltração quando a superfície foi tratada com laser de CO2e jateamento. O uso de autoclave não alterou a microinfiltração entre o soft liner e a base da prótese (AU)

Surface morphology and in vitro leachability of soft liners modified by the incorporation of antifungals for denture stomatitis treatment

Abstract Objective: To evaluate the surface morphology and in vitro leachability of temporary soft linings modified by the incorporation of antifungals in minimum inhibitory concentrations (MIC) for Candida albicans biofilm. Methodology:Specimens of soft lining materials Softone and Trusoft were made without (control) or with the addition of nystatin (Ny), miconazole (Mc), ketoconazole (Ke), chlorhexidine diacetate (Chx), or itraconazole (It) at their MIC for C. albicans biofilm. The surface analyses were performed using Confocal laser scanning microscopy after 24 h, 7 days, or 14 days of immersion in distilled water at 37ºC. In vitro leachability of Chx or Ny from the modified materials was also measured using Ultraviolet visible spectroscopy for up to 14 days of immersion in distilled water at 37ºC. Data (µg/mL) were submitted to ANOVA 1-factor/Bonferroni (α=0.05). Results: Softone had a more irregular surface than Trusoft. Morphological changes were noted in both materials with increasing immersion time, particularly, in those containing drugs. Groups containing Chx and It presented extremely porous and irregular surfaces. Both materials had biexponential release kinetics. Softone leached a higher concentration of the antifungals than Trusoft (p=0.004), and chlorhexidine was released at a higher concentration than nystatin (p<0.001). Conclusions: The surface of the soft lining materials changed more significantly with the addition of Chx or It. Softone released a higher concentration of drugs than Trusoft did, guiding the future treatment of denture stomatitis.

Surgical and nonsurgical treatment of papillary hyperplasia: A case report / Tratamiento quirúrgico y no quirúrgico de la hiperplasia papilar inflamatoria: Reporte de Caso

Dentures with dental plaque predispose recurrent hyperplasia on the palatal mucosa. Surgical procedures for the treatment of inflammatory papillary hyperplasia involve postsurgical discomfort and morbidity. This repot describes clinical and histologic aspects of a patient with severe akantolitic inflammatory papillary hyperplasia. The palatal mucosa was treated with a surgical bur with a low-speed handpiece. A new removable denture was performed and adapted. A follow-up of 4 years showed staility of health at palatal mucosa. Patient referred low discomfort and morbidity when using bur technique. Control of removable denture was critical for long-term healing and soft tissue stability.

Las prótesis dentales con placa bacteriana predisponen a la hiperplasia recurrente en la mucosa palatina. Los procedimientos quirúrgicos para el tratamiento de la hiperplasia papilar inflamatoria implican molestias y morbilidad posquirúrgicas. Este reporte describe los aspectos clínicos e histológicos de un paciente con hiperplasia papilar inflamatoria acantolítica severa. La mucosa palatina fue tratada con una fresa quirúrgica con una pieza de mano de baja velocidad. Se realizó y adaptó una nueva prótesis parcial removible. Después de un seguimiento de 4 años, se encontró estabilidad de la salud de la mucosa palatina. El paciente se refirió a la baja incomodidad y morbilidad al usar la técnica de la fresa. El control de la prótesis parcial removible fue crítico para la cicatrización a largo plazo y la estabilidad de los tejidos blandos, evitando la recidiva de la hiperplasia papilar inflamatoria.

Evaluation of the effect of coating vertex denture lining material with plant oils on microbial growth and hardness

Aims: To evaluate the effect of surface coating with natural plant oils (Salvia officinalis, ginger and eucalyptus) on Candida growth and the hardness of Vertex denture lining material. Materials and method: Forty five specimens were prepared from soft acrylic lining material, twenty five of which were 10x10x2mm in size for testing antifungal activity, and twenty samples were 20mm in diameter and 12mm in thickness, for testing shore A hardness after coating samples with three types of natural oils (Salvia officinalis, ginger and eucalyptus oils). Significant differences among the groups at (p≤0.05) level of significance were determined statistically with one way analysis of variance and Duncan's multiple range test Result: Antifungal assay showed a significant difference between five groups regarding Candida albicans growth (p≤ 0.05). For the hardness test, comparing different times of storage in water (1, 7, 14, 30 days) revealed a significant difference within all groups (p≤0. 05). While comparing the groups coated with natural oils with the control group, significant differences were found between different times of storage in water (1, 7, 30 day) (p≤0.05), except at 14 days of water storage there was no significant difference between groups (p>0.05). Conclusion: All tested natural oils were effective as fungicidal agents and increased the softness and duration of soft acrylic lining material.

Beneficial effects of ethyl-cyanoacrylate coating against candida albicans biofilm formation

Abstract The aim of this study was to verify whether modifications made in a hard chairside reline resin by an ethyl-cyanoacrylate adhesive, ECA (Super Bonder®, Loctite, Itapevi, SP, Brazil) would be able to inhibit or reduce Candida albicans biofilm formation on its surface, comparing to a commercial surface sealant (BisCover®, Bisco, Schaumburg, USA). Reline resin specimens were fabricated and randomly divided into 6 groups (n=8): CG (control group), no surface treatment; ECA1, ECA coating on the surface before sterilization; ECA2, ECA coating after sterilization; ECA3, ECA incorporated in the resin bulk; DPE1, BisCover® coating before sterilization; DPE2, BisCover® coating after sterilization. Specimens were inoculated with C. albicans SC5314 (1x107 cells/mL) and incubated for 24 h. Then, the biofilm were stained with LIVE/DEAD® BaclightTM L7007 Kit and analyzed by Confocal Laser Scanning Microscopy. The images were evaluated by bioImageL® v.2.0 software and total biovolume (µm3), viable cells (%), and covered area (%) were calculated. Data were statistically analyzed by Kruskal-Wallis and Dunn tests (p<0.05). Results showed that ECA-coated groups presented better results, reducing C. albicans biofilm formation. Acquired images revealed that these groups (ECA1 and ECA2) presented a reduced number of cells, mostly in yeast form (less pathogenic), while the other groups presented higher number of cells, mostly in hyphae form (more pathogenic). Based on these findings, a beneficial effect of Super Bonder® coating reline resins surface could be demonstrated, suggesting a promising way to prevent fungal biofilm formation on dentures.

Resumo O objetivo deste estudo foi verificar se as modificações feitas com o adesivo etil cianoacrilato, ECA (Super Bonder ®, Loctite, Itapevi, SP, Brasil) sobre as resinas acrílicas para reembasamento, poderiam inibir ou reduzir a formação de biofilmes de C.albicans sobre sua superfície quando comparado com um selante de superfície comercial (BisCover®, Bisco, Schaumburg, EUA). Amostras de resina acrílica para reembasamento foram fabricadas e divididas aleatoriamente em 6 grupos (n=8): CG (grupo controle), sem tratamento superficial; ECA1, revestimento de ECA na superfície antes da esterilização; ECA2, revestimento de ECA após esterilização; ECA3, ECA incorporado no volume da resina; DPE1, revestimento de BisCover® antes da esterilização; DPE2, revestimento de BisCover® após esterilização. Os espécimes foram inoculados com C. albicans SC5314 (1x107 células/mL) e incubados durante 24 h. Seguidamente, o biofilme foi corado com LIVE/DEAD® BaclightTM L7007 Kit e analisado no microscópio confocal de varredura a laser. As imagens foram avaliadas pelo software bioImageL® v.2.0, no qual foram calculados o biovolume total (μm3), as células viáveis (%) e a área coberta (%). Os dados foram analisados estatisticamente pelos testes de Kruskal-Wallis e Dunn (p<0,05). Os resultados mostraram que os grupos revestidos com ECA apresentaram os melhores resultados, reduzindo a formação do biofilme de C. albicans. As imagens adquiridas revelaram que esses grupos (ECA1 e ECA2) apresentaram um número reduzido de células, principalmente na forma de levedura (menos patogênico), enquanto os outros grupos apresentaram um maior número de células, principalmente na forma de hifas (mais patogênicas). Com base nessas descobertas, encontra-se um efeito benéfico na aplicação do adesivo ECA sobre as superfícies das resinas acrílicas para reembasamento, sugerindo assim uma nova alternativa de prevenir a formação de biofilme fúngico em próteses dentárias.

Antibiofilm activity of an experimental ricinus communis dentifrice on soft denture liners

Abstract The disadvantage of liners materials is the difficulty of biofilm control. It was compared an experimental dentifrice contained Ricinus communis, with commercials dentifrices as antibiofilm activity against microorganisms on denture liner. Six hundred specimens were distributed in 5 groups (n=18/ microorganism): water; experimental dentifrice; specific dentifrice for denture and two conventional dentifrices against C. albicans; C. glabrata; S. mutans; S. aureus; E. coli. Each group had a negative (n=5; without contamination) and positive control (n=15/ microorganism; without cleaning). The antibiofilm activity was evaluated by the method of biofilm formation in triplicate. The specimens were contaminated in a standard way and incubated. After that, manual brushing was performed (60 s), washed with PBS, immersed in liquid culture medium for resuspension and sowing in solid medium. The results (mean of triplicates) were expressed in CFU/mL. The data was submitted to Shapiro-Wilk, ANOVA and Tukey test (p<0.05). The specific dentifrice (1.27±1.20) was the most effective against S. mutans, followed by conventional (Trihydral, 3.13±0.88; Colgate, 2.16±2.02) and experimental (3.81±1.37) dentifrices, which were similar to each other (p=0.008). All of them were different from water (4.79±1.42). The specific (0.21±0.21) and experimental (0.36±0.25) dentifrices were similar against S. aureus, with a higher mean of CFU when compared to conventional (Colgate, 0.06±0.13), which was more efficient (p=0.000). For C. albicans, C. glabrata and E. coli, all dentifrices were similar to water (p=0.186). It was concluded, that the experimental dentifrice was effective against S. aureus and had not efficacy against Candida spp.; S. mutans; E. coli, as occurred with the commercials dentifrices.

Resumo A desvantagem dos materiais resilientes é a dificuldade de controle do biofilme. Este estudo comparou um dentífrico experimental contendo Ricinus communis, com dentifrícios comerciais quanto atividade contra biofilme formado em reembasador de próteses totais. Seiscentos espécimes foram distribuídos em 5 grupos (n=18/microrganismo): água; dentifrício experimental; dentifrício específico para próteses totais e dois convencionais; contra C. albicans; C. glabrata; S. mutans; S. aureus; E. coli. Cada grupo teve um controle negativo (n=5; sem contaminação) e um positivo (n=15/ microrganismo; sem higienização). A atividade contra biofilme foi avaliada pelo método de formação do biofilme, em triplicata. Os espécimes foram contaminados, padronizadamente, e incubados. Posteriormente, foi realizada escovação manual (60 s), lavagem em PBS, imersão em meio de cultura líquido para ressuspensão e semeadura em meio sólido. Os resultados (média das triplicatas) foram expressos em UFC/mL. Os dados foram submetidos aos testes Shapiro-Wilk, ANOVA e Tukey (p<0,05). O dentifrício específico (1,27±1,20) foi o mais eficaz contra S. mutans, seguido dos convencionais (Trihydral, 3,13±0,88; Colgate, 2,16±2,02) e experimental (3,81±1,37), que foram semelhantes entre si (p=0,008). Todos eles foram diferentes da água (4,79±1,42). O dentifrício específico (0,21±0,21) e o experimental (0,36±0,25) foram semelhantes contra S. aureus, com maiores médias de UFC quando comparado ao convencional (Colgate, 0,06±0,13), que foi mais eficiente (p=0,000). Para C. albicans, C. glabrata e E.coli, todos os dentifrícios foram similares à água (p=0,186). Conclui-se que o dentifrício experimental foi efetivo somente contra S. aureus e não foi eficiente perante Candida spp.; S. mutans; E. coli, como ocorrido com os dentifrícios comerciais.

Effects of relining materials on the flexural strength of relined thermoplastic denture base resins

PURPOSE: The aim of this study was to evaluate the effects of relining materials on the flexural strength of relined thermoplastic denture base resins (TDBRs). MATERIALS AND METHODS: For shear bond strength testing, 120 specimens were fabricated using four TDBRs (EstheShot-Bright, Acrytone, Valplast, Weldenz) that were bonded with three autopolymerizing denture relining resins (ADRRs: Vertex Self-Curing, Tokuyama Rebase, Ufi Gel Hard) with a bond area of 6.0 mm in diameter and were assigned to each group (n=10). For flexural strength testing, 120 specimens measuring 64.0×10.0×3.3 mm (ISO-1567:1999) were fabricated using four TDBRs and three ADRRs and were assigned to each group (n=10). The thickness of the specimens measured 2.0 mm of TDBR and 1.3 mm of ADRR. Forty specimens using four TDBRs and 30 specimens using ADRRs served as the control. All specimens were tested on a universal testing machine. For statistical analysis, Analysis of variance (ANOVA) with Tukey's test as post hoc and Spearman's correlation coefficient analysis (P=.05) were performed. RESULTS: Acry-Tone showed the highest shear bond strength, while Weldenz demonstrated the lowest bond strength between TDBR and ADRRs compared to other groups. EstheShot-Bright exhibited the highest flexural strength, while Weldenz showed the lowest flexural strength. Relined EstheShot-Bright demonstrated the highest flexural strength and relined Weldenz exhibited the lowest flexural strength (P < .05). Flexural strength of TDBRs (P=.001) and shear bond strength (P=.013) exhibited a positive correlation with the flexural strength of relined TDBRs. CONCLUSION: The flexural strength of relined TDBRs was affected by the flexural strength of the original denture base resins and bond strength between denture base resins and relining materials.

Surface Properties of Temporary Soft Liners Modified by Minimum Inhibitory Concentrations of Antifungals

Abstract Evaluating the addition of minimum inhibitory concentrations (MICs) of antifungals for Candida albicans biofilm on the hardness and roughness of temporary denture soft liners. Specimens (n=8; 36×7×6 mm) of tissue conditioner (Softone) and resilient liner (Trusoft) were produced either without (control) or with incorporation of drugs at MICs: nystatin (0.032 g/mL), chlorhexidine diacetate (0.064 g/mL), ketoconazole (0.128 g/mL), miconazole (0.256 g/mL) and itraconazole (0.256 g/mL). Specimens were stored in distilled water at 37 °C for 24 h, 7 days and 14 days prior to the hardness/roughness measurements. Data were analyzed by 3-way ANOVA and Tukey HSD test (α=0.05). The addition of the antifungals into both materials demonstrated no evident hardness change or decrease of this property compared with the control, except for miconazole in Softone, which increased the hardness after 14 days (p=0.003). The addition of nystatin into both materials, chlorhexidine in Trusoft and ketoconazole in Softone resulted in no significant changes of roughness compared with the control, after 7 days and 14 days (p>0.05). In these periods, itraconazole increased the roughness of both materials (p<0.001). The addition of all antifungals, except for the miconazole in Softone, resulted in no deleterious effects on the materials’ hardness over the evaluation time. The MICs of nystatin in both temporary soft lining materials, ketoconazole in Softone and chlorhexidine in Trusoft resulted in no deleterious effects for roughness up to 14 days.

Resumo Avaliar a adição de antifúngicos nas mínimas concentrações inibitórias (MCIs) para o biofilme de Candida albicans sobre a dureza e rugosidade da reembasadores resilientes temporários. Foram confeccionados corpos de prova (n=8; 36×7×6 mm) a partir de um condicionador de tecido (Softone) e um reembasador resiliente (Trusoft), sem (controle) ou com a incorporação de fármacos nas MCIs: nistatina (0,032 g/mL), diacetato de clorexidina (0,064 g/mL), cetoconazol (0,128 g/mL), miconazol (0,256 g/mL) e itraconazol (0,256 g/mL). Os corpos de prova foram armazenados em água destilada a 37 °C durante 24 h, 7 dias e 14 dias antes das mensurações de dureza e rugosidade. Os dados foram analisados por ANOVA 3-fatores e teste de Tukey HSD (α=0,05). A adição dos antifúngicos em ambos os materiais não demonstrou nenhuma alteração evidente na dureza ou diminuiu esta propriedade em comparação com o controle, exceto para o miconazol no Softone que aumentou a dureza após 14 dias (p=0,003). A adição de nistatina aos dois materiais, clorexidina no Trusoft e cetoconazol no Softone não resultou em alterações significativas de rugosidade em comparação com o controle após 7 e 14 dias (p>0,05). Nestes períodos, o itraconazol aumentou a rugosidade de ambos os materiais (p<0,001). A adição de todos os antifúngicos, exceto para o miconazol no Softone, não resultou em efeitos deletérios sobre a dureza dos materiais ao longo do tempo de avaliação. As MCIs de nistatina em ambos os materiais reembasadores resilientes temporários, cetoconazol no Softone e clorexidina no Trusoft não produziram efeitos deletérios para a rugosidade em até 14 dias.

Prevalence of Candida albicans and Streptococcus aureus on maxillary obturators, maxillary defects and in saliva: A cross-sectional study / Prevalência de Candida albicans e Streptococcus aureus em obturadores superiores, nos defeitos maxilares e na saliva: Um estudo transversal

Objetivo: este estudo investigou a incidência da adesão de Candida albicans e Staphylococcus aureus em próteses superiores obturadoras com materiais de reembasamento macio utilizados por protesistas. Material e Métodos: entre os anos 2013 e 2014, foram avaliados clinicamente, pacientes com defeitos maxilares devido a cirurgia para remoção de tumores e usuários de próteses obturadoras (n = 21, grupo de estudo) e, as consequências microbiológicas foram comparadas com usuários de prótese total superior (n = 21, controle grupo). Os dados foram coletados sobre características demográficas, tipo histológico de câncer, emprego de quimioterapia ou radioterapia, identificação dos materiais reembasamento macio utilizados e métodos de limpeza praticados nas próteses obturadoras e totais. A presença de Candida albicans foi determinada nos materiais de reembasamento macio ou nas superfícies de polimetilmetacrilato e na cavidade bucal e, Staphylococcus aureus na mucosa nasal e na saliva. Os dados foram analisados utilizando os testes Kruskal Wallis, Fisher-Freeman-Halton (p<0,05). Resultados: A maior quantidade de Candida albicans foi encontrada nas superfícies das próteses, na saliva, nos defeitos no palato duro e no material de reembasamento macio definitivo com 90%, 90% e 70%, respectivamente. A maior quantidade de Staphylococcus aureus foi observada na saliva e na cavidade nasal no grupo de material de reembasamento macio definitivo (50%). Conclusão: o curto período de renovação dos materiais de revestimento pode causar menos colonização de Candida albicans e estomatite protética na cavidade bucal. Os pacientes que sofreram maxilectomia foram mais propensos à colonização de Staphylococcus aureus.(AU)

Objective: This study investigated on the incidence of Candida albicans and Staphylococcus aureus adhesion onto maxillary obturator prostheses with soft lining materials placed by prosthodontists. Material and Methods: Between years 2013 and 2014, patients with maxillary defects due to maxillary tumor surgery and acquired obturator prostheses (n = 21, study group) were clinically evaluated and microbiological outcomes were compared with complete maxillary denture wearers (n = 21, control group). Data were collected on demographic features, histological type of cancer, presence of chemotherapy or radiotherapy, identification of soft lining materials used on obturator prostheses, cleansing methods practiced for obturator and maxillary complete prostheses. The presence of Candida albicans was determined on soft lining materials or polymethylmethacrylate surfaces and in the oral cavity, and Staphylococcus aureus in nasal mucosa and saliva. Data were analyzed using Kruskal Wallis, Fisher-Freeman-Halton tests (p<0.05). Results: The highest amount of Candida albicans was found on surfaces of prostheses, in the saliva and on maxillary defects on the hard palate and on definitive soft lining material with 90%, 90%, and 70%, respectively. The highest amount of Staphylococcus aureus was observed in the saliva and nasal cavity in the definitive soft lining material group (50%). Conclusion: Short renewal period of lining materials may cause less Candida albicans colonisation and denture stomatitis in the oral cavity. Patients who have undergone maxillectomy were more prone to Staphylococcus aureus colonisation.(AU)

Porosity of temporary denture soft liners containing antifungal agents

ABSTRACT Incorporation of antifungals in temporary denture soft liners has been recommended for denture stomatitis treatment; however, it may affect their properties. Objective: To evaluate the porosity of a tissue conditioner (Softone) and a temporary resilient liner (Trusoft) modified by minimum inhibitory concentrations (MICs) of antifungal agents for Candida albicans biofilm. Material and Methods: The porosity was measured by water absorption, based on exclusion of the plasticizer effect. Initially, it was determined by sorption isotherms that the adequate storage solution for specimens (65×10×3.3 mm) of both materials was 50% anhydrous calcium chloride (S50). Then, the porosity factor (PF) was calculated for the study groups (n=10) formed by specimens without (control) or with drug incorporation at MICs (nystatin: Ny-0.032 g, chlorhexidine diacetate: Chx-0.064 g, or ketoconazole: Ke-0.128 g each per gram of soft liner powder) after storage in distilled water or S50 for 24 h, seven and 14 d. Data were statistically analyzed by 4-way repeated measures ANOVA and Tukey's test (α=.05). Results: Ke resulted in no significant changes in PF for both liners in water over 14 days (p>0.05). Compared with the controls, Softone and Trusoft PFs were increased at 14-day water immersion only after addition of Ny and Chx, and Chx, respectively (p<0.05). Both materials showed no significant changes in PF in up to 14 days of S50 immersion, compared with the controls (p>0.05). In all experimental conditions, Softone and Trusoft PFs were significantly lower when immersed in S50 compared with distilled water (p<0.05). Conclusions: The addition of antifungals at MICs resulted in no harmful effects for the porosity of both temporary soft liners in different periods of water immersion, except for Chx and Ny in Softone and Chx in Trusoft at 14 days. No deleterious effect was observed for the porosity of both soft liners modified by the drugs at MICs over 14 days of S50 immersion.

Efeito da incorporação de agentes antifúngicos na resistência à tração e porosidade de materiais resilientes temporários para base de próteses / Effect of incorporation of antifungal agents on the ultimate tensile strength and porosity of temporary soft denture liners

Este estudo investigou a resistência à tração (ou limite de resistência à tração- LRT) e a porosidade de reembasadores resilientes temporários modificados por concentrações inibitórias mínimas (CIMs) de agentes antifúngicos para o biofilme Candida albicans (SC5314). Para os testes de LRT, corpos de prova em forma de halteres (n=7) com uma área transversal de 33 mm x 6 mm x 3 mm foram produzidos para os materiais resilientes (Trusoft e Softone) sem (controle) ou com incorporação de cinco fármacos em suas CIMs: nistatina- 0,032 g; diacetato de clorexidina- 0,064; cetoconazol- 0,128 g; miconazol- 0,256 g; itraconazol-0,256 g (grama de fármaco por grama de pó de material resiliente). Após a plastificação, as amostras foram imersas em água destilada a 37°C durante 24 h, 7 e 14 dias e, então, testadas em tensão em uma máquina universal de ensaios (EMIC DL-500 MF) a 40 mm/min. A porosidade foi mensurada por absorção de água, com base na exclusão do efeito plastificante. Inicialmente, determinou-se por isotermas de sorção, que a solução de armazenagem adequada para os corpos de prova (65 mm x 10 mm x 3,3 mm) de ambos os materiais foi o cloreto de cálcio anidro a 50% (S50). Assim, o fator de porosidade (FP) foi calculado para os grupos de estudo (n=10) formados por espécimes sem (controle) ou com incorporação de fármaco em suas CIMs (nistatina, clorexidina ou cetoconazol) após a armazenagem em água destilada ou S50 por 24 h, 7 e 14 dias. Os dados de resistência à tração (MPa) e percentagem de alongamento (%) foram submetidos à ANOVA de 3 fatores seguida pelo teste de Tukey (=0,05). Os dados de porosidade foram analisados estatisticamente por ANOVA de medidas repetidas para 4 fatores e teste de Tukey (=0,05). Ao final de 14 dias, a resistência à tração para ambos os materiais foi significativamente menor nos grupos modificados pelo miconazol e itraconazol em relação aos outros grupos (P<0,0001), que não mostraram diferenças significativas entre si (P>0,05). Após 7 e 14 dias em água, o miconazol e itraconazol adicionados a ambos os materiais resultaram em percentagens significativamente menores de alongamento em comparação com os outros fármacos e ao controle (P<0,0001), que foram semelhantes entre si (P>0,05). O cetoconazol não resultou em alterações significativas no FP para ambos os materiais resilientes em água ao longo de 14 dias (P>0,05). Em comparação aos controles, houve aumento dos FPs do Softone e Trusoft aos 14 dias de imersão em água somente após a adição de nistatina e clorexidina e de clorexidina, respectivamente (P<0,05). Ambos os materiais não apresentaram alterações significativas no FP em até 14 dias de imersão na S50, em comparação aos controles (P>0,05). Em todas as condições experimentais, os FPs do Softone e Trusoft foram significativamente menores quando imersos em S50 em comparação com a água destilada (P<0,05). Concluiu-se que a adição de nistatina, clorexidina e cetoconazol nas CIMs para o biofilme de C. albicans não resultou em efeitos deletérios na resistência à tração e na percentagem de alongamento dos materiais resilientes temporários para base de prótese até o período de 14 dias. A adição de antifúngicos nas CIMs não resultou em efeitos adversos à porosidade de ambos os materiais resilientes temporários em diferentes períodos de imersão em água, com exceção da clorexidina e nistatina no Softone e clorexidina no Trusoft aos 14 dias. Não foram observados efeitos deletérios para a porosidade de ambos os materiais resilientes modificados com as CIMs dos fármacos durante os 14 dias de imersão na S50.(AU)

This study investigated the tensile strength (ultimate tensile strength- UTS) and porosity of temporary soft denture liners modified by minimum inhibitory concentrations (MICs) of antifungal agents for Candida albicans biofilm (SC5314). For UTS tests, dumbbell-shaped specimens (n=7) with a central cross-sectional area of 33 mm x 6 mm x 3 mm were produced by resilient materials (Trusoft and Softone) without (control) or with incorporation of five drugs at MICs: nystatin- 0.032 g; chlorhexidine diacetate-0.064 g; ketoconazole- 0.128 g; miconazole- 0.256 g; itraconazole- 0.256 g (each per gram of soft liner powder). After plasticization, specimens were immersed in distilled water at 37°C for 24 h, 7 and 14 days, and then tested in tension in a universal testing machine (EMIC DL-500 MF) at 40 mm/min. The porosity was measured by water absorption, based on exclusion of the plasticizer effect. Initially, it was determined by sorption isotherms that the adequate storage solution for specimens (65 mm x 10 mm x 3.3 mm) of both materials was 50% anhydrous calcium chloride (S50). Then, the porosity factor (PF) was calculated for the study groups (n=10) formed by specimens without (control) or with drug incorporation at MICs (nystatin, chlorhexidine or ketoconazole) after storage in distilled water or S50 for 24 h, 7 and 14 days. Data of tensile strength (MPa) and elongation percentage (%) were submitted to 3-way ANOVA followed by Tukey's test (=0.05). Data of porosity were statistically analyzed by 4-way repeated measures ANOVA and Tukeys test (=0.05). At the end of 14 days, the tensile strength for both materials was significantly lower in the groups modified by miconazole and itraconazole compared to the other groups (P<0.0001), which showed no significant difference between them (P>0.05). After 7 and 14 days in water, miconazole and itraconazole added into both materials result in significant lower elongation percentages compared to the other drugs and control (P<.0001), which were similar to each other (P>0.05). Ketoconazole resulted in no significant changes in PF for both liners in water over 14 days (P>0.05). Compared to the controls, Softone and Trusoft PFs were increased at 14-day water immersion only after addition of nystatin and chlorhexidine, and chlorhexidine, respectively (P<0.05). Both materials showed no significant changes in PF in up to 14 days of S50 immersion, compared to the controls (P>0.05). In all experimental conditions, Softone and Trusoft PFs were significantly lower when immersed in S50 compared to distilled water (P<0.05). It was concluded that the addition of the nystatin, chlorhexidine and ketoconazole at MICs for C. albicans biofilm resulted in no harmful effects on the ultimate tensile strength and elongation percentage of the temporary soft denture liners up to 14-day period. The addition of antifungals at MICs resulted in no detrimental effects for the porosity of both temporary soft liners in different periods of water immersion, except for chlorhexidine and nystatin in Softone and chlorhexidine in Trusoft at 14 days. No deleterious effect was observed for the porosity of both soft liners modified by the drugs at MICs over 14 days of S50 immersion.(AU)

Biocompatibilidade in vivo de material resiliente temporário para base de prótese modificado por antimicrobianos para tratamento da estomatite protética / Biocompatibility in vivo of temporary soft denture liner for denture base modified by antimicrobials agents for denture stomatitis treatment

Reembasadores resilientes temporários contendo fármacos antifúngicos foram sugeridos como um tratamento adjunto para estomatite protética. No entanto, antes de utilizar clinicamente estes reembasadores modificados em humanos, é importante avaliar a sua biocompatibilidade em modelos animais. Este estudo avaliou a biocompatibilidade in vivo de um reembasador resiliente temporário para base de prótese (Trusoft) modificado por agentes antimicrobianos em suas mínimas concentrações inibitórias (MCIs) para biofilme de Candida albicans. Dispositivos acrílicos intra-orais (DIOs) foram confeccionados individualmente para 60 ratos Wistar. Os ratos foram divididos em 6 grupos (n=5): 3 grupos controle (Negativo: sem DIO; Geral: DIO sem reembasamento; Positivo: DIO reembasado com Trusoft sem fármacos) e 3 grupos experimentais (DIOs reembasados com Trusoft modificados por fármacos em suas respectivas MCIs: 0,032 g de nistatina, 0,064 g de diacetato de clorexidina e 0,128 g de cetoconazol). Os ratos com ou sem os DIOs foram eutanasiados após 7 e 14 dias de avaliação. A análise histopatológica qualitativa foi realizada comparando-se fotomicrografias de secções histológicas, que foram obtidas utilizando um microscópio óptico que abrangeu transversalmente a região intermolares. As alterações morfológicas no epitélio e queratina foram analisadas quantitativamente através da realização de planimetria computadorizada. Os dados quantitativos foram analisados utilizando ANOVA 2-fatores e teste de Tukey (=0,05). A análise quantitativa mostrou que apenas o grupo com DIO contendo cetoconazol diminuiu significativamente a espessura e a área do estrato córneo em comparação com os outros grupos (p<0,05), que não apresentaram diferenças significativas entre si (p>0,05). Estes resultados estiveram de acordo com os obtidos para análise qualitativa. A incorporação de MCIs de nistatina e diacetato de clorexidina no Trusoft não induziram alterações histopatológicas na mucosa palatina de ratos, sugerindo a biocompatibilidade in vivo deste protocolo para o tratamento de estomatite protética.(AU)

Temporary resilient denture liners containing antifungal drugs have been suggested as an adjunct treatment for denture stomatitis. However, before clinically using these modified liners in humans, it is important to assess their biocompatibility in animal models. This study evaluated the in vivo biocompatibility of a temporary soft denture liner (Trusoft) modified by antimicrobial agents at their minimum inhibitory concentrations (MICs) for biofilm formation by Candida albicans. Methods: Acrylic intraoral devices (IODs) were individually made for 60 Wistar rats. The rats were divided into the following 6 groups (n=5): 3 control groups (Negative: without IOD; General: IOD without relining; Positive: IOD relined with Trusoft without drugs) and 3 experimental groups (IOD relined with Trusoft modified by drugs at MICs: 0.032 g for nystatin, 0.064 g for chlorhexidine diacetate, and 0.128 g for ketoconazole). The rats with or without the IODs were sacrificed after 7 or 14 days of evaluation. Histopathological qualitative analysis was performed by comparing photomicrographs of histological sections, which were obtained using an optical microscope that transversely covered the inter-molar region. Morphological changes in the epithelium and keratin were quantitatively analyzed by performing computerized planimetry. Quantitative data were analyzed using 2-way ANOVA and Tukey's test (=0.05). Quantitative analysis showed that only the group with IOD containing ketoconazole significantly decreased the thickness and area of the stratum corneum compared with the other groups (p<0.05), which showed no significant differences between each other (p>0.05). These results were in accordance with those obtained for qualitative analysis. Incorporation of MICs of nystatin and chlorhexidine diacetate in Trusoft did not induce histopathological changes in the palatal mucosa of rats, suggesting the in vivo biocompatibility of this protocol for treating denture stomatitis.(AU)

A influência da incorporação de clorexidina nas propriedades mecânicas de resinas macias para bases de dentaduras / The influence of chlorhexidine incorporation on the mechanical properties of soft resin for denture bases

A incorporação do diacetato de clorexidina em resinas macias para o reembasamento de próteses removíveis pode se tornar um método eficaz no combate à Candida albicans, principal agente causador da Estomatite Protética. Dessa forma, este trabalho teve como objetivo avaliar os efeitos da incorporação do diacetato de clorexidina nas propriedades mecânicas e na rugosidade superficial de duas resinas macias, uma à base de polimetilmetacrilato (PMMA) e outra à base de polietilmetacrilato (PEMA), nas seguintes concentrações: 0% (Controle), 1% (C1) e 2% (C2). Com exceção dos corpos de prova utilizados no tempo T0, os demais foram armazenados em água destilada a 37ºC durante 2, 7 e 14 dias e então analisados quanto a resistência à tração, ao cisalhamento e quanto a rugosidade superficial. Após 14 dias de imersão em água destilada, os resultados do teste de tração indicaram um aumento na resistência dos grupos que receberam diacetato de clorexidina em relação ao grupo Controle, em ambas as resinas (p<0,05). Neste mesmo período, o teste de cisalhamento indicou não ter havido diferença estatísticamente significante entre os grupos quando a resina à base de PEMA foi testada (p>0,05), ao passo que a resina à base de PMMA demonstrou uma dimnuição da resistência do grupo C2, em relação aos demais.Após 14 dias, os testes de rugosidade superficial indicaram que para a resina à base de PMMA, houve uma diminuição da rugosidade superficial do grupo C1 em relação ao grupo C2 (p<0,05). Para a resina à base de PEMA foi possível verificar uma diminuição da rugosidade superficial em ambos os grupos incorporados com diacetato de clorexidina, em relação ao grupo Controle, no 14ºdia de imersão em água destilada (p<0,05). Dessa forma, é possível concluir que a incorporação do diacetato de clorexidina não afetou negativamente as propriedades mecânicas e a rugosidade superficial das resinas macias testadas.

The incorporation of chlorhexidine diacetate in soft resins for the relining of removable dentures can become an effective method against Candida albicans, the main causative agent of Prosthetic stomatitis. Thus, this study aimed to evaluate the effects of incorporation of chlorhexidine diacetate on the mechanical properties and surface roughness of two soft resins, one based on polymethylmethacrylate (PMMA) and another based on polyethyl methacrylate (PEMA), the following concentrations : 0% (control), 1% and 2% . Except for specimens of control group (0%), the others were stored in distilled water at 37 ° C for 48 hours, 7 days and 14 days and then analyzed for tensile strength, shear strength and the surface roughness. After 14 days of immersion in distilled water, the results of tensile testing indicated an increase in resistance of the groups that received chlorhexidine diacetate in relation to the control group in both resins (p <0.05). In the same period, the shear test indicated there was no statistically difference between the groups when the PEMA based resin was tested (p> 0.05), while the PMMA based resin showed a decreased of resistance to 2% group, compared to the others. After 14 days, the surface roughness tests indicated that for the PMMA based resin, there was a decrease of surface roughness of the 1% group compared to the 2% group (p <0.05). For PEMA based resin, was verified a decrease in surface roughness in both groups incorporated with chlorhexidine diacetate, compared to the control group, from the seventh day of immersion in distilled water (p <0.05). Thus, it can be concluded that incorporation of chlorhexidine diacetate did not negatively affect the mechanical properties and the surface roughness of the tested soft resins.

Effect of thermocycling in a hard denture liner and acrylic resin after different chemical and mechanical polishing / Efeito da termociclagem em reembasador rígido para prótese e resina acrílica após polimento químico e mecânico

Objective: To evaluate the effect of aging in a hard denture reline (New Truliner) and an acrylic resin (Classic) after chemical and mechanical polishing. Methods: Eighty specimens were made, divided randomly between 8 groups: G1.Acrylic Resin Classic (RAC)/Mechanical Polishing (PM); G2.RAC/PM + thermocycling (TR); G3) RAC/Chemical Polishing (PQ); G4.RAC/PQ + TR; G5.New Truliner (NT)/PM; G6.NT/PM + TR; G7. NT/PQ; G8.NT/PQ + TR. The surface hardness was measured before and after polishing, and after TR. The impact resistance tests were measured after all applied treatments. The data were submitted to ANOVA and Tukey test (a=5%). Results: Regardless of the polishing, it was noted that RAC presented significantly higher surface hardness than NT; PM had higher hardness in both materials compared with PQ; on both polishing, the impact resistance of the RAC was higher than NT. Independently of TR test, the impact resistance of the materials that received PQ was higher than received PM. The PQ caused greater changes in properties than the PM. Conclusion: Aging and chemical and mechanical polishing influenced the physical and mechanical properties of hard denture reline and acrylic resin.

Objetivo: Avaliar o efeito da termociclagem em reembasador rígido para próteses totais (New Truliner) e resina acrílica (Clássico) após polimento químico e mecânico. Métodos: Foram confeccionados 80 corpos de prova, divididos de forma randomizada entre 8 grupos: G1. Resina Acrílica Clássico (RAC)/Polimento mecânico (PM); G2. RAC/PM + termociclagem (TR); G3.RAC/Polimento químico (PQ); G4.RAC/PQ + TR; G5.New Truliner (NT)/PM; G6.NT/PM + TR; G7. NT/PQ; G8. NT/PQ + TR. A dureza superficial foi mensurada antes e após os polimentos, e após a TR. Os ensaios de resistência ao impacto foram mensurados após todos os tratamentos. Os dados foram submetidos à análise de variância e Tukey (a=0,05). Resultados: Independente do polimento verificou-se que RAC apresentou resultados de dureza superficial significativamente mais altos que NT; PM gerou superfícies mais duras em ambos os materiais quando comparado ao PQ; em ambos os polimentos, os valores de resistência ao impacto da RAC foram maiores que os do NT. Independentemente da realização da TR, a resistência ao impacto dos materiais que receberam PQ foi maior que a dos que receberam PM. PQ causou maior alteração nas propriedades do que PM. Conclusão: A termociclagem e os polimentos químico e mecânico influenciam as propriedades físicas e mecânicas do reembasador rígido e da resina acrílica.

Effect of the addition of propolis on a soft denture liner on bond strength with an acrylic resin / Efeito da adição de própolis em um reembasador resiliente de prótese na resistência de união com resina acrílica

Objective ­ To evaluate the effect on bond strength of an acrylic resin and thermoatived resilient denture liner material with different concentrations of propolis. Methods ­ Fourty eight specimens of acrylic resin (Lucitone 550, Dentsply) were made and united with the soft liner (Coe Soft, GC America) with different concentrations of propolis: group 1 (control) ­ only Coe Soft; Group 2 ­ Coe Soft + 75 mg of propolis; Group 3 ­ Coe Soft + 150 mg of propolis, and Group 4 ­ Coe Soft + 300 mg of propolis. The union traction resistance test was performed, and the type of fracture was evaluated. The data were analyzed descriptively and by one-way ANOVA, followed by Tukey's test (p=0.05). Results ­ There was no difference between the control group and when 75 mg of propolis was added (p>0.05), while the group with 150 mg of propolis showed lower bond strength (p<0.05), However, group 4 did not differ from the others (p>0.05). Regarding the kind of fails, the control group and group 2 showed the same failures: 91.7% cohesive and 8.3% adhesive. Group 3 showed only cohesive failure, and group 4 had cohesive failures (58.4%), adhesive (8.3%) and mixed (33.3%). Conclusions ­ It can be concluded that 75 mg of propolis extract may be considered the most suitable concentration to be added in the soft denture liner, considering that the properties of soft denture liner was not changed.

Objetivo ­ Avaliar o efeito na resistência de união entre resina acrílica e reembasador resiliente de prótese termoativado com diferentes concentrações de própolis. Métodos ­ Quarenta e oito espécimes de resina acrílica (Lucitone 550, Dentsply) foram confeccionados e unidos ao reembasador resiliente (Coe Soft, GC América) com diferentes concentrações de própolis: Grupo 1 (controle) ­ apenas o Coe Soft, Grupo 2 ­ Coe Soft + 75 mg de própolis; Grupo 3 ­ Coe Soft + 150 de própolis e Grupo 4 ­ Coe Soft + 300 mg de própolis. Foi realizado o teste de resistência à tração e o tipo de fratura foi avaliado. Os dados foram analisados de forma descritiva e através de análise de variância a um critério, seguido pelo teste de Tukey (p=0,05). Resultado ­ Não houve diferença entre o grupo controle e quando 75 mg de própolis foi adicionao (p>0,05), enquanto o grupo com 150 mg de própolis mostrou menor resistência de união (p<0,05). No entanto, o grupo 4 não diferiu dos demais (p>0,05). Em relação ao tipo de falha, o grupo controle e o grupo 2 apresentaram as mesmas falhas: 91,7% coesivas e 8,3% adesivas. O grupo 3 obteve apenas falha coesiva, e o grupo 4 teve falhas coesivas (58,4%), adesivas (8,3%) e mistas (33,3%). Conclusões ­ Conclui-se que 75mg de extrato de própolis pode ser considerada a concentração mais adequada para ser adicionada ao reembasador de prótese, considerando-se que as propriedades deste reembasador resiliente de prótese não foram alteradas.

Comparative evaluation of tensile bond strength of silicone‑based denture liners after thermocycling and surface treatment.

Purpose: To examine, evaluate, and compare the tensile bond strength of two silicone‑based liners; one autopolymerizing and one heat cured, when treated with different chemical etchants to improve their adhesion with denture base resin. Materials and Methods: Hundred and sixty test specimens of heat‑cured polymethyl methacrylate (PMMA) were fabricated; out of which 80 specimens were tested for tensile bond strength after bonding it to autopolymerizing resilient liner (Ufigel P) and rest 80 to heat‑cured resilient liner (Molloplast B). Each main group was further divided into four subgroups of 20 specimens each, one to act as a control and three were subjected to surface treatment with different chemical etchants namely dichloromethane, MMA monomer, and chloroform. The two silicone‑based denture liners were processed between 2 PMMA specimens (10 mm × 10 mm × 40 mm) in the space provided by a spacer of 3 mm, thermocycled (5–55°C) for 500 cycles, and then their tensile strength measurements were done in the universal testing machine. Results: One‑way ANOVA technique showed a highly significant difference in the mean tensile bond strength values for all the groups. The Student’s t‑test computed values of statistics for the compared groups were greater than the critical values both at 5% and at 1% levels. Conclusion: Surface treatment of denture base resin with chemical etchants prior to the application of silicone‑based liner (Ufigel P and Molloplast‑B) increased the tensile bond strength. The increase was the highest with specimens subjected to 180 s of MMA surface treatment and the lowest with control group specimens.

Soft denture liners and sodium perborate: sorption, solubility and color change

Abstract Aim: To evaluate the sorption, solubility and color change in two lining materials after 120 days of immersion in either sodium perborate or artificial saliva. Methods: Thirty disk-shaped specimens (15×3 mm) of each material, Mucopren(r) soft (MS) and Elite(r) soft (ES) were manufactured and divided into two groups. The specimens in the control group (CG, n=15) were stored in artificial saliva at 37 °C. The specimens in the experimental group (EG, n=15) were stored in artificial saliva at 37 °C and immersed in sodium perborate daily for 5 min. The analysis of sorption and solubility was based on the initial dry weight and on the wet and dry weights after immersion. The color was assessed with a portable spectrophotometer and the NBS system. ANOVA and Tukey test (p<0.05) were used to analyze color and sorption. The solubility was analyzed by KruskalWallis test (p<0.05). Results: Sorption was higher in the EG group (0.31±0.08) than in the control group (0.26±0.05), and higher in Elite(r) soft relining (0.34±0.07) than in Mucopren(r) soft (0.23±0.06). There was no interaction between the factors. Elite(r) Soft presented a higher solubility when immersed in artificial saliva (CG: 0.16±0.07 and EG: 0.13±0.06; p=0.00). Mucopren(r) soft showed no solubility in either treatment. Regarding the color changes, there was a significant difference between the groups (CG: 9.2±1.2 and EG: 9.9±1.2; p=0.025) but not between the materials (Mucopren(r) soft: 9.4±1.3 and Elite(r)soft: 9.7±1.0; p=0.34). Using the NBS system, we verified that both materials presented a high color change. Conclusions: The daily use of sodium perborate promoted changes in the liners' sorption and color. Elite(r) soft relining was more prone to changes than Mucopren(r) soft.

Candida albicans biofilms and MMA surface treatment influence the adhesion of soft denture liners to PMMA resin

The effect of Candida albicans biofilms and methyl methacrylate (MMA) pretreatment on the bond strength between soft denture liners and polymethyl methacrylate (PMMA) resin was analyzed. Specimens were prepared and randomly divided with respect to PMMA pretreatment, soft liner type (silicone-based or PMMA-based), and presence or absence of a C. albicans biofilm. Samples were composed of a soft denture liner bonded between two PMMA bars. Specimens (n = 10) were incubated to produce a C. albicans biofilm or stored in sterile PBS for 12 days. The tensile bond strength test was performed and failure type was determined using a stereomicroscope. Surface roughness (SR) and scanning electron microscopy (SEM) analysis were performed on denture liners (n = 8). Highest bond strength was observed in samples containing a silicone-based soft liner and stored in PBS, regardless of pretreatment (p < 0.01). Silicone-based specimens mostly underwent adhesive failures, while samples containing PMMA-based liners predominantly underwent cohesive failures. The silicone-based specimens SR decreased after 12 days of biofilm accumulation or PBS storage, while the SR of PMMA-based soft liners increased (p < 0.01). The PMMA-based soft liners surfaces presented sharp valleys and depressions, while silicone-based specimens surfaces exhibited more gentle features. In vitro exposure to C. albicans biofilms reduced the adhesion of denture liners to PMMA resin, and MMA pretreatment is recommended during relining procedures.

Effect of silica coating and silane surface treatment on the bond strength of soft denture liner to denture base material

OBJECTIVE: This study investigated the effects of different surface treatments on the tensile bond strength of an autopolymerizing silicone denture liner to a denture base material after thermocycling. MATERIAL AND METHODS: Fifty rectangular heat-polymerized acrylic resin (QC-20) specimens consisting of a set of 2 acrylic blocks were used in the tensile test. Specimens were divided into 5 test groups (n=10) according to the bonding surface treatment as follows: Group A, adhesive treatment (Ufi Gel P adhesive) (control); Group S, sandblasting using 50-µm Al2O3; Group SCSIL, silica coating using 30-µm Al2O3 modified by silica and silanized with silane agent (CoJet System); Group SCA, silica coating and adhesive application; Group SCSILA, silica coating, silane and adhesive treatment. The 2 PMMA blocks were placed into molds and the soft lining materials (Ufi Gel P) were packed into the space and polymerized. All specimens were thermocycled (5,000 cycles) before the tensile test. Bond strength data were analyzed using 1-way ANOVA and Duncan tests. Fracture surfaces were observed by scanning electron microscopy. X-ray photoelectron spectrometer (XPS) and Fourier Transform Infrared spectrometer (FTIR) analysis were used for the chemical analysis and a profilometer was used for the roughness of the sample surfaces. RESULTS: The highest bond strength test value was observed for Group A (1.35±0.13); the lowest value was for Group S (0.28±0.07) and Group SCSIL (0.34±0.03). Mixed and cohesive type failures were seen in Group A, SCA and SCSILA. Group ...