Quantitative analysis of S. mutans and S. sobrinus cultivated independently and adhered to polished orthodontic composite resins

In Orthodontics, fixed appliances placed in the oral cavity are colonized by microorganisms. OBJECTIVE: The purpose of this study was to quantitatively determine the independent bacterial colonization of S. mutans and S. sobrinus in orthodontic composite resins. MATERIAL AND METHODS: Seven 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). RESULTS: Significant 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. CONCLUSIONS: This 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

Microscopy: advances in scientific research and education

Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Sperctroscopy (EDS) are two analysis techniques that are widely used to study all kinds of solid samples, from inorganic to biological. They are used to determine morphological features of interest at a micron and sub-micron level as well as to study the chemical composition of the samples in terms of the amount of each element present. Although these analytical techniques are “routine work” in many research areas, it is not the case of the dental area, mainly because the lack of this equipment in the dental research institutes and in dental schools. Therefore, in this chapter we show the SEM/EDS techniques applied to human dental samples when irradiated with a laser Er:YAG to prevent caries. The intention of this work is to show step by step this analysis showing the key variables to consider when working with this type of biological samples. We explain the SEM conditions to obtain satisfactory images especially when it is important to follow a sequence of steps of a treatment in-vitro that changes the morphological structure of the teeth surface. Also, we discuss the EDS analysis to semiquantitatively determine the elements and their abundance in the dental samples

ADHESION OF Candida albicans AND Streptococcus mutans TO SILVER NANOPARTICLE-MODIFIED POLYMETHYLMETHACRYLATE

"This in vitro study independently evaluated the adhesion of Candida albicans (ATCC 18804) and Streptococcus mutans (ATCC 25175) to polymethylmethacrylate (PMMA) blocks modified with silver nanoparticles (AgNPs). A total of 160 samples were used, separat