Ana Maria Martins Brandão

In vitro analysis of shear bond strength and adhesive remnant index comparing light curing and self-curing composites

OBJECTIVE To evaluate, in vitro, the shear bond strength of self-curing (ConciseTM - 3M and Alpha Plast - DFL) and light-curing composites (TransbondTM XT - 3M and Natural Ortho - DFL) used in orthodontics bonding, associated to Morelli metal brackets, with further analysis of adhesive remnant index (ARI) and enamel condition in scanning electron microscopy (SEM). METHODS Forty human premolars, just extracted and stored in physiologic solution 0.9 % were used. Randomly, these samples were divided in four groups: G1 group, the brackets were bonded with ConciseTM - 3M composite; in G2 group, Alpha Plast - DFL composite was used; in G3 group, TransbondTM XT - 3M was used; in G4 group, Natural Ortho - DFL composite was used. These groups were submitted to shear strength tests in universal testing machine, at 0.5 mm per minute speed. RESULTS Statistical difference between G3 and G4 groups was recorded, as G4 showing higher strength resistance than G3. In the other hand, there were no statistical differences between G1, G2 and G3 and G1, G2 and G4 groups. ARI analysis showed that there was no statistical difference between the groups, and low scores were recorded among then. The scanning electron microscopy (SEM) analysis revealed the debonding spots and the enamel surface integrity. CONCLUSIONS Shear bond strength was satisfactory and similar between the composites, however Natural Ortho - DFL revealed best comparing to TransbondTM XT - 3M.

Does the bracket composition material influence initial biofilm formation

CONTEXT Orthodontic treatment has been reported to contribute to the development and accumulation of dental biofilm, which is commonly found on bracket and adjacent surfaces. AIMS The aim of this work is to test the hypothesis if there are differences in dental biofilm formation on the surface of orthodontic brackets according to the type of composition material. SUBJECTS AND METHODS Three bracket types (metallic, composite, and ceramic) had been evaluated. Subjects wore acrylic palatal orthodontic appliances, containing 6 brackets each, for two 3-day cycles. On the end of first cycle, the amount of dental biofilm formed on the samples was extracted using 1.0-M NaOH and analyzed by spectrophotometry for quantification. An additional cycle was carried out to verify the dental biofilm formation using scanning electronic microscope analysis. STATISTICAL ANALYSIS USED Three-way ANOVA was used to analyze the difference among the materials (metallic, ceramic and composite) concerning the dental biofilm absorbance spectrum. Multiple comparisons were made using the Tukeys test (α =0.05). RESULTS Composite brackets showed greater values concerning biofilm formation, when compared with the metallic and ceramic ones, both of which presented similar scores. The hypothesis is accepted. There are differences on the biofilm formation according to the type of material. CONCLUSIONS The in situ model tested was found to be effective in evaluating the accumulation and development of biofilm on orthodontic brackets. In the quantitative analysis, composite brackets showed greater biofilm adhesion values while metallic and ceramic presented similar biofilm absorbance spectrum.

Evaluation of ionic degradation and slot corrosion of metallic brackets by the action of different dentifrices

OBJECTIVE To evaluate the in vitro ionic degradation and slot base corrosion of metallic brackets subjected to brushing with dentifrices, through analysis of chemical composition by Energy Dispersive Spectroscopy (EDS) and qualitative analysis by Scanning Electron Microscopy (SEM). METHODS Thirty eight brackets were selected and randomly divided into four experimental groups (n = 7). Two groups (n = 5) worked as positive and negative controls. Simulated orthodontic braces were assembled using 0.019 x 0.025-in stainless steel wires and elastomeric rings. The groups were divided according to surface treatment: G1 (Máxima Proteção Anticáries®); G2 (Total 12®); G3 (Sensitive®); G4 (Branqueador®); Positive control (artificial saliva) and Negative control (no treatment). Twenty eight brushing cycles were performed and evaluations were made before (T0) and after (T1) experiment. RESULTS The Wilcoxon test showed no difference in ionic concentrations of titanium (Ti), chromium (Cr), iron (Fe) and nickel (Ni) between groups. G2 presented significant reduction (p < 0.05) in the concentration of aluminium ion (Al). Groups G3 and G4 presented significant increase (p < 0.05) in the concentration of aluminium ion. The SEM analysis showed increased characteristics indicative of corrosion on groups G2, G3 and G4. CONCLUSION The EDS analysis revealed that control groups and G1 did not suffer alterations on the chemical composition. G2 presented degradation in the amount of Al ion. G3 and G4 suffered increase in the concentration of Al. The immersion in artificial saliva and the dentifrice Máxima Proteção Anticáries® did not alter the surface polishing. The dentifrices Total 12®, Sensitive® and Branqueador® altered the surface polishing.

Percepções de estudantes de graduação em Odontologia sobre o Sistema de Saúde Brasileiro

Oral health policies prior to implementation of the Unified Health System (SUS), were considered mutually exclusive and directed to healing practices. Indicators showed little contribution to the improvement of oral health. The SUS institution allowed the direction of Brazilian public health to preventive, humane and integrated actions. The aim of this study was to analyze the profile of the dental student of the Federal University of Para according with the professional interests and the performance in the SUS. We used an inductive approach with procedure statistical-comparative and extensive direct technique observation through a questionnaire. From the sample universe of 478 students enrolled of 1st to 10th semester, extracted a sample of 240 students (confidence level 95%). It was found that for 93.8% the SUS construction dependent of the union of users, government and professionals interested in offering best services. The students say that training in dentistry at is directed to the work in the SUS and the human sciences are important for professional practice. The subjects addressed and practical activities developed were considered insufficient for professional practice.