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.

Efficacy of citric acid denture cleanser on the Candida albicans biofilm formed on poly(methyl methacrylate): effects on residual biofilm and recolonization process.

BACKGROUND: It is well known that the use of denture cleansers can reduce Candida albicans biofilm accumulation; however, the efficacy of citric acid denture cleansers is uncertain. In addition, the long-term efficacy of this denture cleanser is not well established, and their effect on residual biofilms is unknown. This in vitro study evaluated the efficacy of citric acid denture cleanser treatment on C. albicans biofilm recolonization on poly(methyl methacrylate) (PMMA) surface. METHODS: C. albicans biofilms were developed for 72 h on PMMA resin specimens (n = 168), which were randomly assigned to 1 of 3 cleansing treatments (CTs) overnight (8 h). CTs included purified water as a control (CTC) and two experimental groups that used either a 1:5 dilution of citric acid denture cleanser (CT5) or a 1:8 dilution of citric acid denture cleanser (CT8). Residual biofilms adhering to the specimens were collected and quantified at two time points: immediately after CTs (ICT) and after cleaning and residual biofilm recolonization (RT). Residual biofilms were analyzed by quantifying the viable cells (CFU/mL), and biofilm architecture was evaluated by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Denture cleanser treatments and evaluation periods were considered study factors. Data were analyzed using two-way ANOVA and Tukey's Honestly Significant Difference (HSD) test (α = 0.05). RESULTS: Immediately after treatments, citric acid denture cleansing solutions (CT5 and CT8) reduced the number of viable cells as compared with the control (p < 0.01). However, after 48 h, both CT groups (CT5 and CT8) showed biofilm recolonization (p < 0.01). Residual biofilm recolonization was also detected by CLSM and SEM analysis, which revealed a higher biomass and average biofilm thickness for the CT8 group (p < 0.01). CONCLUSION: Citric acid denture cleansers can reduce C. albicans biofilm accumulation and cell viability. However, this CT did not prevent biofilm recolonization.

Influência das propriedades de superfícies dos implantes com as respostas dos tecidos moles e formação de biofilme / The influence of implant surface properties with soft tissue response and biofilm formation

Uma conexão estável entre a superfície de titânio do implante e os tecidos bucais a sua volta é um importante pré-requisito para o seu sucesso a longo prazo. Assim, tal superfície deve possuir propriedades que minimizem a colonização por microrganismos patogênicos da cavidade oral ao mesmo tempo em que permita boa adesão dos tecidos bucais. O objetivo deste estudo foi realizar uma revisão da literatura que buscasse relacionar as diferentes propriedades de superfícies dos implantes e suas características com as respostas dos tecidos moles peri-implantares, bem como com a formação de biofilme sobre sua superfície. Estudos in vitro e in vivo indicaram que a rugosidade e a textura de superfície do implante influenciam em adesão, orientação, proliferação, metabolismo das células epiteliais e células de tecido conjuntivo. Foi descrito também que a rugosidade superficial e a molhabilidade têm um impacto significativo na formação de biofilme, sendo que a influência da rugosidade foi dita como sendo mais significativa do que a molhabilidade. Sendo assim, nota-se que a otimização das superfícies dos implantes ainda é necessária. Tornando-se importante analisar o papel das propriedades de diferentes superfícies com relação à composição química e à microestrutura, avaliando o desempenho biológico dos diferentes tratamentos de superfícies e as propriedades químicas que eles promovem na superfície dos implantes dentários.

A stable connection between the titanium surface and the oral tissue around them is an important prerequisite for long-term dental implant success. Thus, this surface should minimize the bacterial colonization while allowing a good adhesion of the oral tissues. The aim of this study was to review the literature and to relate the properties of implant surfaces and their characteristics with the responses of oral soft tissues around implants, as well as the biofilm formation on its surface. In vitro and in vivo studies indicated that the roughness and texture of the implant surface influences the adhesion, orientation, proliferation, and metabolism of epithelial cells and connective tissue. It was also described that the surface roughness and wettability, have a significant impact on the biofilm formation, but the influence of roughness was said to be more significant than the wettability. In summary, it appears that an optimization of implant surfaces is still necessary. It is therefore important to systematically evaluate the role of different surface properties (chemical composition as well as microstructure) and to assess the biological performance of different implant materials.