Probiotic Effect of Streptococcus dentisani on Oral Pathogens: An In Vitro Study.

Probiotics, including Streptococcus dentisani, have been proposed as an alternative to re-establish the ecology of the oral cavity and inhibit the formation of pathogenic biofilms. The main objective of this work was to assess the probiotic ability of S. dentisani against Streptococcus mutans, Streptococcus mitis, and Candida albicans biofilms. The ability of the strains to form a monospecies biofilm and the probiotic potential of S. dentisani using the competition, exclusion, and displacement strategies were determined. All strains were moderate biofilm producers. The ability of S. dentisani to compete with and exclude S. mutans and S. mitis during biofilm formation was not significant. However, S. dentisani significantly reduced pathologic streptococcal biofilms using the displacement strategy. Also S. dentisani reduced the formation of the C. albicans biofilm mainly through competition and displacement. In vitro, S. dentisani exhibited probiotic potential to reduce the formation of potentially pathogenic biofilms. Further investigation is required to understand the biofilm-inhibiting mechanisms exhibited by this probiotic strain.

Assessment of Polydopamine to Reduce Streptococcus mutans Adhesion to a Dental Polymer.

Bacterial adhesion to the surface of materials is the first step in biofilm formation, which will lead to conditions that may compromise the health status of patients. Recently, polydopamine (PDA) has been proposed as an antibacterial material. Therefore, the objective of the current work was to assess and compare the adhesion of Streptococcus mutans to the surface of poly(methyl methacrylate) (PMMA) discs that were modified using PDA following a biomimetic approach versus smooth PDA-coated PMMA surfaces. In addition, an assessment of the growth inhibition by PDA was performed. PMMA discs were manufactured and polished; soft lithography, using the topography from the Crocosmia aurea leaf, was used to modify their surface. PDA was used to smooth-coat PMMA discs by dip-coating. The growth inhibition was measured using an inhibition halo. The surfaces were characterized by means of atomic force microscopy (AFM), the contact angle (CA), and Fourier-transform infrared spectroscopy (FTIR). Polydopamine exhibited a significant antibacterial effect when used directly on the S. mutans planktonic cells, but such an effect was not as strong when modifying the PMMA surfaces. These results open the possibility of using polydopamine to reduce the adhesion and growth of S. mutans, which might have important consequences in the dental field.

Translucency of a Dental Porcelain Mixed by Two Ceramic Slurry Methods: A Bayesian Comparison.

Background: The ceramics industry produces porcelain pastes using a controlled ratio of water and porcelain powder. Two methods are used to produce a dental porcelain paste: one-step mixing or incremental mixing. Objective: To evaluate the optical properties of a feldspathic dental ceramic using two different ceramic paste preparation methods using a Bayesian approach. Materials and Methods: Two groups of feldspathic porcelain discs, an incremental mixing group (n = 40) and a one-step mixing group (n = 40), were assessed. Groups were evaluated using spectrophotometry, and the translucency parameter (TP) of each sample was calculated. Surfaces were characterized by AFM and SEM. Statistical analysis was performed using a Bayesian approach. Results: Translucency parameter values of the incremental mixing group ranged from 1.65 to 3.41, while values for the one-step mixing group ranged from 3.62 to 5.74, this difference being statistically significant. The lowest roughness was obtained on the surface of discs in the one-step mixing group. Conclusions: Feldspathic porcelain with lower translucency and higher roughness was obtained using the incremental mixture method.

Bioinspired Topographic Surface Modification of Biomaterials.

Physical surface modification is an approach that has been investigated over the last decade to reduce bacterial adhesion and improve cell attachment to biomaterials. Many techniques have been reported to modify surfaces, including the use of natural sources as inspiration to fabricate topographies on artificial surfaces. Biomimetics is a tool to take advantage of nature to solve human problems. Physical surface modification using animal and vegetal topographies as inspiration to reduce bacterial adhesion and improve cell attachment has been investigated in the last years, and the results have been very promising. However, just a few animal and plant surfaces have been used to modify the surface of biomaterials with these objectives, and only a small number of bacterial species and cell types have been tested. The purpose of this review is to present the most current results on topographic surface modification using animal and plant surfaces as inspiration to modify the surface of biomedical materials with the objective of reducing bacterial adhesion and improving cell behavior.

Chemical, structural and mechanical characterization of bovine enamel.

OBJECTIVE: The purpose of this investigation was to establish microstructure, microhardness, fracture toughness, chemical composition, and crack repair of bovine enamel and to compare these features with their human counterparts. DESIGN: Bovine enamel fragments were prepared and optical microscopy and atomic force microscopy were used to establish microstructure; Raman spectroscopy was used to estimate composition and microindentation using Vickers testing was performed to evaluate hardness. RESULTS: A strong dependence between indentation load and microhardness values was observed, as was the case in human enamel. Similar microstructure and chemical composition between bovine and human enamel, 7.89% lower microhardness and 40% higher fracture toughness values for bovine enamel were found. CONCLUSION: From a structural and mechanical standpoint, bovine enamel is a suitable alternative to human enamel for in vitro testing of dental products.

A novel approach to create an antibacterial surface using titanium dioxide and a combination of dip-pen nanolithography and soft lithography.

Soft lithography and Dip-Pen Nanolithography (DPN) are techniques that have been used to modify the surface of biomaterials. Modified surfaces play a role in reducing bacterial adhesion and biofilm formation. Also, titanium dioxide has been reported as an antibacterial substance due to its photocatalytic effect. This work aimed at creating patterns on model surfaces using DPN and soft lithography combined with titanium dioxide to create functional antibacterial micropatterned surfaces, which were tested against Streptococcus mutans. DPN was used to create a master pattern onto a model surface and microstamping was performed to duplicate and transfer such patterns to medical-grade stainless steel 316L using a suspension of TiO2. Modified SS316L plates were subjected to UVA black light as photocatalytic activator. Patterns were characterized by atomic force microscopy and biologically evaluated using S. mutans. A significant reduction of up to 60% in bacterial adhesion to TiO2 -coated and -micropatterned surfaces was observed. Moreover, both TiO2 surfaces reduced the viability of adhered bacteria after UV exposure. TiO2 micropatterned demonstrated a synergic effect between physical and chemical modification against S. mutans. This dual effect was enhanced by increasing TiO2 concentration. This novel approach may be a promising alternative to reduce bacterial adhesion to surfaces.