In situ bacterial accumulation on dental restorative materials. CLSM/COMSTAT analysis.

PURPOSE: To evaluate the influence of different restorative materials on the biofilm structure accumulated in situ. METHODS: 15 discs of each material (ceramic; resin composite; resin-modified and conventional glass-ionomers; amalgam) were adapted to palatal devices in order to accumulate biofilm in situ, under a cariogenic challenge (20% sucrose solution, 10x/day). After 7 days, the specimens were carefully removed and visualized by confocal laser scanning microscopy (CLSM). The images were analyzed qualitatively (descriptive analysis about cell viability and architecture) and quantitatively using COMSTAT software (area, bio-volume, mean thickness, maximum thickness and roughness coefficient of the biofilm). The statistical analysis was performed by using the Kolmogorov-Smirnov and Kruskal-Wallis tests (P ≤ 5%). RESULTS: The medians of the biofilm parameters analyzed showed no statistical difference regarding different materials. However, qualitatively, glass-ionomer cements and amalgam showed visually a prevalence of non-viable cells forming small clusters distributed by the biofilm, and voids were presented in smaller proportion in the biofilm volume compared to composite and ceramic.

Determination of the properties of an experimental glass polyalkenoate cement prepared from niobium silicate powder containing fluoride.

OBJECTIVES: The purpose of this paper is to modify the conventional calcium fluoro-alumino-silicate glass, which is used in the formation of glass ionomer cements (CIGs) by the niobium addition and to study the properties of GICs obtained. MATERIALS AND METHODS: Sol-gel process was used to prepare the powder at lower temperature than fusion method. Glass-ceramic powder obtained in this way was used to prepare the GICs. The properties such as working and setting times, microhardness and diametral tensile strength were evaluated for the experimental GICs and a commercial luting cement. RESULTS: The ideal powder:liquid (P:L) ratio determined to prepare the experimental GICs was equal to 1:1. The cements prepared using this ratio showed working and setting times similar to the commercial GICs. In mechanical tests it was observed that microhardness and diametral tensile strength of the experimental GICs decreased significantly with the reduction of P:L ratio. On the other hand, the results obtained in microhardness tests indicated that the presence of niobium was a positive factor. SIGNIFICANCE: The chemical process allows the development of glass-ceramic powder at 600 degrees C which is the goal of the present paper. It was concluded that GICs containing niobium might be used in dental applications and these results encourage further researches on other compositions.

Advances in Dental Materials through Nanotechnology: Facts, Perspectives and Toxicological Aspects.

Nanotechnology is currently driving the dental materials industry to substantial growth, thus reflecting on improvements in materials available for oral prevention and treatment. The present review discusses new developments in nanotechnology applied to dentistry, focusing on the use of nanomaterials for improving the quality of oral care, the perspectives of research in this arena, and discussions on safety concerns regarding the use of dental nanomaterials. Details are provided on the cutting-edge properties (morphological, antibacterial, mechanical, fluorescence, antitumoral, and remineralization and regeneration potential) of polymeric, metallic and inorganic nano-based materials, as well as their use as nanocluster fillers, in nanocomposites, mouthwashes, medicines, and biomimetic dental materials. Nanotoxicological aspects, clinical applications, and perspectives for these nanomaterials are also discussed.