Rodrigo Matos de Souza

Nickel, chromium and iron levels in the saliva of patients with simulated fixed orthodontic appliances.

OBJECTIVE To assess the in vivo release of nickel, chromium, and iron ions into saliva by different metallic brackets. MATERIALS AND METHODS Thirty volunteers wore removable appliances with bonded brackets and were divided according to the brand of brackets: group A, 3M/Unitek (AISI 303); group B, American Orthodontics (AISI 316L); and group C, Dentaurum (AISI 316L). The appliances were worn for 60 days, and saliva samples were collected at the following time points: T1, before placement of the appliance; T2, after 10 minutes; T3, 24 hours; T4, 7 days; T5, 30 days; and T6, 60 days after insertion of the removable appliance. Saliva samples were analyzed for nickel, chromium, and iron by atomic absorption spectrophotometry. Statistical analysis was performed by nonparametric tests (Friedman, Mann-Whitney, Kruskal-Wallis). RESULTS Saliva evaluation revealed a large variation in concentration of these ions between individuals. The results also appeared to indicate an increase in nickel and chromium ions immediately after placement of the appliance (T2), but this was statistically significant only for groups B and C. There was no increase in iron levels. A tendency for increases in nickel and chromium concentrations was verified immediately after placement of the appliance, but these values are probably reduced because of biofilm formation regardless of the bracket used. CONCLUSION Nickel and chromium ion concentrations increased immediately after placement of the appliance in the mouth for all study groups. There were no significant differences in the nickel, chromium, and iron levels released by the three groups of appliances at all study periods.Abstract Objective: To assess the in vivo release of nickel, chromium, and iron ions into saliva by different metallic brackets. Materials and Methods: Thirty volunteers wore removable appliances with bonded brackets and were divided according to the brand of brackets: group A, 3M/Unitek (AISI 303); group B, American Orthodontics (AISI 316L); and group C, Dentaurum (AISI 316L). The appliances were worn for 60 days, and saliva samples were collected at the following time points: T1, before placement of the appliance; T2, after 10 minutes; T3, 24 hours; T4, 7 days; T5, 30 days; and T6, 60 days after insertion of the removable appliance. Saliva samples were analyzed for nickel, chromium, and iron by atomic absorption spectrophotometry. Statistical analysis was performed by nonparametric tests (Friedman, Mann-Whitney, Kruskal-Wallis). Results: Saliva evaluation revealed a large variation in concentration of these ions between individuals. The results also appeared to indicate an increase in nickel and chromiu...

Biodegradação de braquetes ortodônticos: análise por microscopia eletrônica de varredura

OBJECTIVES: The purpose of this study was to analyze, with the aid of scanning electron microscopy (SEM), the chemical and structural changes in metal brackets subjected to an in vitro biodegradation process. METHODS: The sample was divided into three groups according to brackets commercial brand names, i.e., Group A = Dyna-Lock, 3M/Unitek (AISI 303) and Group B = LG standard edgewise, American Orthodontics (AISI 316L). The specimens were simulated orthodontic appliances, which remained immersed in saline solution (0.05%) for a period of 60 days at 37°C under agitation. The changes resulting from exposure of the brackets to the saline solution were investigated by microscopic observation (SEM) and chemical composition analysis (EDX), performed before and after the immersion period (T0 and T5, respectively). RESULTS: The results showed, at T5, the formation of products of corrosion on the surface of the brackets, especially in Group A. In addition, there were changes in the composition of the bracket alloy in both groups, whereas in group A there was a reduction in iron and chromium ions, and in Group B a reduction in chromium ions. CONCLUSIONS: The brackets in Group A were less resistant to in vitro biodegradation, which might be associated with the type of steel used by the manufacturer (AISI 303).

Clinical characteristics, lung function and airway inflammatory patterns of Brazilian children with severe therapy-resistant asthma

Results 20 children with STRA (mean age: 11.3±2.9 years; 62% males) were included, and paired with 70 children with mild asthma and 27 healthy controls. 18/20 (90%) STRA children were atopic, and only 2/20 (10%) were sensitized to pets. Lung function from children with STRA was not different from the other groups studied. From 13 STRA children with induced sputum obtained, we have found seven, four and two neutrophilic, eosinophilic and paucigranulocytic patterns, respectively. The number/percentage of inflammatory cells and pattern of sputum inflammation were not different between children with STRA (n=13) and milder asthma (n=70). From 5 sputums repeated in STRA children, 4 (80%) had the inflammatory pattern changed. Six STRA patients are under omalizumab treatment. Conclusion Children with STRA have nearly normal lung function and their airway inflammatory pattern seems not to be different from children with milder asthma. The mechanisms involved in the uncontrolled disease of children with STRA are not clear and should be better addressed in future studies.