Evaluation of biofilm formation on acrylic resin surfaces coated with silicon dioxide: an in situ study.

Biofilm on acrylic resin dental prostheses may cause gingival inflammation. This study evaluated the influence of a silicon dioxide coating layer applied onto acrylic resin on the adhesion of microorganisms. Blocks (5 x 5 x 3 mm) of acrylic resin were evaluated for surface roughness and divided into two groups: control (CG) and coated with silicon dioxide (LG group). The specimens were evaluated by scanning electron microscopy (n = 1) and by contact angle analysis (n = 3). For the in situ study, 20 volunteers wore acrylic palatal devices containing three samples from each group (n = 60) for 2 days. The biofilm formed was quantified by metabolic activity and total biomass using the crystal violet assay. The results were subjected to Bartlett's normality test and Gamma model with random effect for the response variable (α = 5%). The mean contact angle of the coated group was significantly lower than that of the uncoated group (p < 0.05). The metabolic activity of microorganisms in the biofilm on the blocks treated with coating was significantly lower than that of control blocks (p = 0.02). Regarding the amount of extracellular matrix produced by the microorganisms, there was no difference between the CG and LG group (p = 0.05). The application of a silicon dioxide coating on acrylic resin reduced the activity of the polymicrobial biofilm formed in situ. This coating may be advantageous for patients with conventional complete dentures or implants made of acrylic resin and who have motor difficulties that prevent them from cleaning their prostheses properly

Translucency parameter of conventional restorative glass-ionomer cements.

OBJECTIVE: To evaluate the translucency parameter (TP) and contrast ratio (CR) of different conventional restorative glass-ionomer cements (GICs). MATERIALS AND METHODS: Eighteen brands of GICs were evaluated. Five disks of each material were made following ISO 9917-1. The luminous reflectance and Central Bureau of the International Commission on Illumination parameters of disks were evaluated using a colorimeter, against backings of white and black, to obtain the translucent parameter and contrast ratio of different brands of glass-ionomer cements. The correlation between translucency parameter and contrast ratio was assessed with the Pearson correlation test. The translucent and contrast ratio parameters values were submitted to the one-way ANOVA and Tukey test for multiple comparisons (p < 0.05). RESULTS: There was a strong inverse relationship between CR and TP (r2 = 0.94, p < 0.001). The contrast ratio decreased as translucency increased. There were significant differences in TP and CR among brands (p < 0.001). CONLUSIONS: GICs exhibit different translucency and contrast ratio behavior. Some brands of GICs presented very low TP and this condition would be unacceptable for areas with esthetic demands. In addition, TP and CR showed a strong linear relationship. CLINICAL SIGNIFICANCE: The results found in this study demonstrated that the knowledge of the translucency and CR of different conventional restorative GICs is important in order to guide clinicians in the selection of restorative GICs for anterior teeth

The relationship between smile attractiveness and esthetic parameters of patients with lateral agenesis treated with tooth recontouring or implants

Luciana Manzotti De-Marchi,1 N&amp;uacute;bia Inocencya Pavesi Pini,2 Renata Corr&amp;ecirc;a Pascotto31Department of Dentistry, University Center of Maring&amp;aacute;-CESUMAR, Maring&amp;aacute;-PR/Brazil; 2Piracicaba Dental School, State University of Campinas, Piracicaba-SP/Brazil; 3Department of Dentistry, State University of Maring&amp;aacute;, Maring&amp;aacute;-PR/BrazilBackground: The purpose of this study was to associate smile esthetic judgment with dentofacial attributes of patients with unilateral and bilateral agenesis of maxillary lateral incisors treated with recontouring of canines or implants and patients with no agenesis (control).Material and methods: Forty-six participants were divided into two groups: those treated with recontouring (N = 26) and those treated with implants (N = 20). The participants in the control group (N = 22) were selected among dentistry students at the State University of Maring&amp;aacute;, Brazil. Photographs of posed smiles (17 cm &amp;times; 10 cm) were evaluated with a 100-mm Visual Analog Scale. Smile attractiveness was judged by two groups: laypersons and dentists (N = 20 in each group). Judgment was classified into Unpleasant and Pleasant. Measurements of 11 smile attributes were done with ImageTool Version 3.0. These measurements were correlated with the type of judgment using the Pearson correlation coefficient.Results: The two groups of evaluators showed no rating difference (analysis of variance, P = 0.64), thus they were placed into a single group. No significant correlation was found between esthetic judgment and six smile attributes (incisor exposure, interlabial gap, width 3 to 3, smile index, right buccal corridor, and buccal corridor ratio). The control group showed more correlations with the unpleasant judgment type than the other groups.Conclusion: Some correlations between smile attributes and esthetic judgment were found, but other features of smiles not evaluated in this study may interfere in smile attractiveness.Keywords: esthetic, dental agenesis, attractiveness, dental implants, composite resin, perceptio

Mechanical and optical properties of conventional restorative glass-ionomer cements - a systematic review.

OBJECTIVES: To perform a systematic review of test methodologies on conventional restorative glass-ionomer cement (GIC) materials for mechanical and optical properties to compare the results between different GICs. MATERIAL AND METHODS: Screening of titles and abstracts, data extraction, and quality assessments of full-texts were conducted in search for in vitro studies on conventional GICs that follow the relevant specifications of ISO standards regarding the following mechanical and optical properties: compressive strength, flexural strength, color, opacity and radiopacity. SOURCES: The Latin American and Caribbean Health Sciences (LILACS), Brazilian Bibliography of Dentistry (BBO) databases from Latin-American and Caribbean System on Health Sciences Information (BIREME) and PubMed/Medline (US National Library of Medicine - National Institutes of Health) databases were searched regardless of language. Altogether, 1146 in vitro studies were selected. Two reviewers independently selected and assessed the articles according to pre-established inclusion/exclusion criteria. Among all the properties investigated, only one study was classified as being of fair quality that tested compressive strength and was included. It was observed that many authors had not strictly followed ISO recommendations and that, for some properties (diametral tensile strength and microhardness), there are no guidelines provided. CONCLUSIONS: It was not possible to compare the results for the mechanical and optical properties of conventional restorative GICs due to the lack of standardization of studies