Background: The purpose of the study is to assess the antiadherent and antibacterial properties of surfacemodified different orthodontic brackets with silver nanoparticles against Streptococcus mutans and Streptococcus sobrinus, using radiomarker. Methods: In this study evaluated quantitatively the adherence of Streptococci to orthodontic brackets, 300 samples of orthodontic brackets were selected and classified in to 10 groups as follow: GIn (InVu-Roth), GIIn (System-AlexanderLTS), GIIIn (Gemini-Roth), GIVn (NuEdge-Roth), GVn (Radiance plus-Roth), GVI (InVu-Roth), GVII (System-AlexanderLTS), GVIII (Gemini-Roth), GIX (NuEdge-Roth), GX (Radiance plus-Roth). All the samples were sonicated and Streptococci were cultivated by gender. A radioactive marker (3 H) was used to codify the bacteria and measure them. After that, the brackets were submerged in a radiolabelled solution, and the radiation was measured. The statistical analysis was calculated with ANOVA test (Sheffè post hoc). Results: The results showed significant differences were found among the groups. GIIIn shown the lowest scores for both bacteria; in contrast, GIX for Streptococcus mutans and GVI for Streptococcus sobrinus were the highest values. Conclusions: Surface modification of orthodontic brackets with silver nanoparticles can be used to prevent the accumulation of dental plaque and the development of dental caries during orthodontic treatment.

In Orthodontics, fixed appliances placed in the oral cavity are colonized by microorganisms.ObjectiveThe purpose of this study was to quantitatively determine the independent bacterial colonization of S. mutans and S. sobrinus in orthodontic composite resins. Material and methodsSeven orthodontic composite adhesives for bonding brackets were selected and classified into 14 groups; (GIm, GIs) Enlight, (GIIm, GIIs) Grengloo, (GIIIm, GIIIs) Kurasper F, (GIVm, GIVs) BeautyOrtho Bond, (GVm, GVs) Transbond CC, (GVIm, GVIs) Turbo Bond II, (GVIIm, GVIIs) Blugloo. 60 blocks of 4x4x1 mm of each orthodontic composite resin were made (total 420 blocks), and gently polished with sand-paper and ultrasonically cleaned. S. mutans and S. sobrinus were independently cultivated. For the quantitative analysis, a radioactive marker was used to codify the bacteria (3H) adhered to the surface of the materials. The blocks were submerged in a solution with microorganisms previously radiolabeled and separated (210 blocks for S. mutans and 210 blocks for S. sobrinus) for 2 hours at 37ºC. Next, the blocks were placed in a combustion system, to capture the residues and measure the radiation. The statistical analysis was calculated with the ANOVA test (Sheffè post-hoc). ResultsSignificant differences of bacterial adhesion were found amongst the groups. In the GIm and GIs the significant lowest scores for both microorganisms were shown; in contrast, the values of GVII for both bacteria were significantly the highest. ConclusionsThis study showed that the orthodontic composite resin evaluated in the GIm and GIs, obtained the lowest adherence of S. mutans and S. sobrinus, which may reduce the enamel demineralization and the risk of white spot lesion formation.

Silver nanoparticles (AgNPs) are used for their powerful antibacterial effect and their ability to adhere to surfaces due to their size; they are used in different areas of life, mainly in the area of health as medicine. More recently, in dentistry, the synthesis and characterization of AgNPs attracted significant attention due to their antibacterial properties. In this study, the AgNPs were synthesized using the most effective method on different orthodontic brackets (metallic and esthetic) and characterized by scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) and transmission electron microscopy (TEM). Their antimicrobial effect was tested against the widely used standard human pathogens Staphylococcus aureus (Gram-negative) and Escherichia coli (Gram-positive). Our results showed that, via a simple chemical method, AgNPs can be synthesized on the surface of orthodontic brackets with good antimicrobial activity and the possibility of reducing dental decay, periodontal disease and white spots generated during orthodontic treatment.

The surface roughness, morphology and shear bond strength (SBS) of dental zirconia using three different surface treatment techniques were evaluated. Three groups of sintered zirconia blocks were treated as follow, 1) Airborne-particle abrasion (APA) group (G1-APA), 50-µm Al2O3; 2) APA and 9% hydrofluoric acid etching (G2-HF); 3) APA and Sodium Hydroxide (G3-NaOH). The specimens were evaluated for roughness [atomic force microscope (AFM)], morphology [Scanning Electron Microscope (SEM)] and for SBS in the universal testing machine. The AFM revealed changes in the roughness after the surface treatments, however there was not Ra difference between groups, SEM analysis revealed changes in surface morphology for all surface treated specimens. For SBS, significant difference was found between G1-APA=8.4±2.7 MPa and G2-HF=3.3±0.6 MPa (p<0.05) and G2-HF and G3-NaOH=9.0±3.0 MPa (p<0.05). The main fracture mode was mixed failure (63%) for G1-APA and G3-NaOH groups. G2-HF showed 100% adhesive failure. SBS was improved with NaOH, however application of HF significantly decreased SBS.

Laser irradiation has been proposed as a preventive method against dental caries since it is capable to inhibit enamel demineralization by reducing carbonate and modifying organic matter, yet it can produce significant morphological changes. The purpose of this study was to evaluate the influence of Er:YAG laser irradiation on superficial roughness of deciduous dental enamel and bacterial adhesion. Fifty‐four samples of deciduous enamel were divided into three groups (n = 18 each). G1_control (nonirradiated); G2_100 (7.5 J/cm2) and G3_100 (12.7 J/cm2) were irradiated with Er:YAG laser at 7.5 and 12.7 J/cm2, respectively, under water irrigation. Surface roughness was measured before and after irradiation using a profilometer. Afterwards, six samples per group were used to measure bacterial growth by XTT cell viability assay. Adhered bacteria were observed using confocal laser scanning microscopy (CLSM) and a scanning electron microscopy (SEM). Paired t‐, one‐way analysis of variance (ANOVA), Kruskal‐Wallis and pairwise Mann–Whitney U tests were performed to analyze statistical differences (p < .05). Before treatment, samples showed homogenous surface roughness, and after Er:YAG laser irradiation, the surfaces showed a significant increase in roughness values (p < .05). G3_100 (12.7 J/cm2) showed the highest amount of Streptococcus mutans adhered (p < .05). The increase in the roughness of the tooth enamel surfaces was proportional to the energy density used; the increase in surface roughness caused by laser irradiation did not augment the adhesion of Streptococcus sanguinis; only the use of the energy density of 12.7 J/cm2 favored significantly the adhesion of S. mutans.