Nanotopography and oral bacterial adhesion on titanium surfaces: in vitro and in vivo studies

Abstract The present study aimed to evaluate the influence of titanium surface nanotopography on the initial bacterial adhesion process by in vivo and in vitro study models. Titanium disks were produced and characterized according to their surface topography: machined (Ti-M), microtopography (Ti-Micro), and nanotopography (Ti-Nano). For the in vivo study, 18 subjects wore oral acrylic splints containing 2 disks from each group for 24 h (n = 36). After this period, the disks were removed from the splints and evaluated by microbial culture method, scanning electron microscopy (SEM), and qPCR for quantification of Streptococcus oralis, Actinomyces naeslundii, Fusobacterium nucleatum, as well as total bacteria. For the in vitro study, adhesion tests were performed with the species S. oralis and A. naeslundii for 24 h. Data were compared by ANOVA, with Tukey's post-test. Regarding the in vivo study, both the total aerobic and total anaerobic bacteria counts were similar among groups (p > 0.05). In qPCR, there was no difference among groups of bacteria adhered to the disks (p > 0.05), except for A. naeslundii, which was found in lower proportions in the Ti-Nano group (p < 0.05). In the SEM analysis, the groups had a similar bacterial distribution, with a predominance of cocci and few bacilli. In the in vitro study, there was no difference in the adhesion profile for S. oralis and A. naeslundii after 24 h of biofilm formation (p > 0.05). Thus, we conclude that micro- and nanotopography do not affect bacterial adhesion, considering an initial period of biofilm formation.

Effect of iodonium salt and chitosan on the physical and antibacterial properties of experimental infiltrants

Abstract Resinous infiltrants are indicated in the treatment of incipient carious lesions, and further development of these materials may contribute to greater control of these lesions. The aim of this study was to analyze the physical and antibacterial properties of experimental infiltrants containing iodonium salt and chitosan. Nine experimental infiltrants were formulated by varying the concentration of the diphenyliodonium salt (DPI) at 0, 0.5 and 1 mol%; and chitosan at 0, 0.12 and 0.25 g%. The infiltrants contained the monomeric base of triethylene glycol dimethacrylate and bisphenol-A dimethacrylate ethoxylate in a 75 and 25% proportion by weight, respectively; 0.5 mol% camphorquinone and 1 mol% ethyl 4-dimethylaminobenzoate. The degree of conversion was evaluated using Fourier transformer infrared spectroscopy, and the flexural strength and elastic modulus using the three-point bending test. Sorption and solubility in water, and antibacterial analysis (minimum inhibitory concentration and minimum bactericidal concentration) were also analyzed. Data was analyzed statistically by two-way ANOVA and Tukey's test (p<0.05), with the exception of the antibacterial test, which was evaluated by visual inspection. In general, the infiltrant group containing 0.5% DPI and 0.12% chitosan showed high values of degree of conversion, higher values of elastic modulus and flexural strength, and lower sorption values in relation to the other groups. Antibacterial activity was observed in all the groups with DPI, regardless of the concentration of chitosan. The addition of DPI and chitosan to experimental infiltrants represents a valid option for producing infiltrants with desirable physical and antibacterial characteristics.

In vitro effects of Melaleuca alternifolia essential oil on growth and production of volatile sulphur compounds by oral bacteria

ABSTRACT Objective Halitosis can be caused by microorganisms that produce volatile sulphur compounds (VSCs), which colonize the surface of the tongue and subgingival sites. Studies have reported that the use of natural products can reduce the bacterial load and, consequently, the development of halitosis. The aim of this study was to evaluate the antimicrobial activity of the essential oil of Melaleuca alternifolia on the growth and volatile sulphur compound (VSC) production of oral bacteria compared with chlorhexidine. Material and Methods The effects of these substances were evaluated by the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) in planktonic cultures of Porphyromonas gingivalis and Porphyromonas endodontalis. In addition, gas chromatography analyses were performed to measure the concentration of VSCs from bacterial cultures and to characterize M. alternifolia oil components. Results The MIC and MBC values were as follows: M. alternifolia - P. gingivalis (MIC and MBC=0.007%), P. endodontalis (MIC and MBC=0.007%=0.5%); chlorhexidine - P. gingivalis and P. endodontalis (MIC and MBC=1.5 mg/mL). M. alternifolia significantly reduced the growth and production of hydrogen sulfide (H2S) by P. gingivalis (p<0.05, ANOVA-Dunnet) and the H2S and methyl mercaptan (CH3SH) levels of P. endodontalis (p<0.05, ANOVA-Dunnet). Chlorhexidine reduced the growth of both microorganisms without altering the production of VSC in P. endodontalis. For P. gingivalis, the production of H2S and CH3SH decreased (p<0.05, ANOVA-Dunnet). Conclusion M. alternifolia can reduce bacterial growth and VSCs production and could be used as an alternative to chlorhexidine.

Atividade do óleo de melaleuca alternifólia sobre o crescimento e expressão gênica de Porphyromonas gingivalis / Evaluation of Melaleuca alternifolia activity on growth and gene expression of Porphyromonas gingivalis

As doenças periodontais são infecções causadas por microrganismos que colonizam a superfície dental na margem gengival ou abaixo dela. Entre eles estão os patógenos periodontais, como Porphyromonas gingivalis. Estudos demonstraram que o óleo essencial extraído de Melaleuca alternifolia tem atividade inibitória e bactericida contra microrganismos da cavidade oral. Este estudo teve como objetivo avaliar a interferência do óleo de Melaleuca (MO) sobre o crescimento e virulência de P. gingivalis, comparando com a atividade da clorexidina (CL). Culturas dessa bactéria foram expostas a diferentes concentrações de MO e CL a fim de avaliar a atividade antimicrobiana através dos testes de concentração inibitória mínima (CIM) e concentração bactericida mínima (CBM). Foi realizada uma análise da expressão diferencial de genes relacionados ao estresse oxidativo e à virulência de P. gingivalis através da técnica de RT-PCR, utilizando concentrações sub-CIM de MO e CL. As CIM e CBM encontradas para MO foram de 0,007% e para CL 1,5 μg/mL. O óleo de melaleuca reduziu significativamente a expressão dos genes de virulência kgp e ragA, e do estresse oxidativo dps, oxyR e sodB, enquanto que a CL reduziu a expressão do gene tpx (ANOVA, Bonferroni, p<0,05). O presente estudo concluiu que o óleo de Melaleuca possui ótima atividade inibitória e bactericida contra a bactéria P. gingivalis, além de reduzir de forma significante a expressão dos genes relacionados à virulência e ao estresse oxidativo, podendo ter um valor terapêutico futuro, principalmente no tratamento das periodontites.

Periodontal diseases are infections caused by microorganisms that colonize the tooth surface at the gingival margin or beneath it. Porphyromonas gingivalis is considered an important pathogen for chronic periodontitis. Studies have shown that the essential oil extracted from Melaleuca alternifolia has inhibitory and bactericidal activity against microorganisms from the oral cavity. Therefore, this study aimed to evaluate the effects of Melaleuca essential oil (MO) on growth and virulence of P. gingivalis, comparing to the activity of chlorhexidine (CL). Cultures of P. gingivalis were exposed to different concentrations of CL and MO to evaluate the antimicrobial activity by testing the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). An analysis of differential expression of genes related to oxidative stress and virulence of P. gingivalis was carried out through RT-PCR method, using sub-MIC concentrations of MO and CL. The MIC and MBC were found to be 0.007% for MO and 1.5 μg/mL for CL. MO significantly reduced the expression of virulence genes kgp and ragA, and oxidative stress genes dps, oxyR and sodB, while CL reduced the expression of the tpx gene (ANOVA, Bonferroni, p<0.05). This study concluded that Melaleuca essential oil presents an excellent inhibitory and bactericidal activity against the bacterium P. gingivalis, and significantly reduces the expression of genes related to virulence and oxidative stress, so may have a therapeutic value, particularly for periodontitis.