RESUMO
Background: Orthodontic treatment makes the patient susceptible to the development of white spot lesions (WSL) due to the greater accumulation of bacterial plaque. The purpose of this in-vitro study was to evaluate the preventive effect of two resin materials on the incidence of these lesions in the region adjacent to the fixed bracket bonded under a WSL-treated area by two resin materials. Material and Methods: 36 extracted human molars presenting natural WSL were included. They were randomly divided into 2 groups for intervention: IC (Infiltration resin Icon®) and PS (resin sealant Pro Seal ®). Braces were bonded just above the WSL. The enamel surface around the brace was treated by one of the tested materials, leaving another part to be control. The samples were submitted again to a cariogenic challenge. The exposed enamel non-treated area from booth groups comprised the control group (E). For morphological analysis, confocal images were taken at baseline, after treatment, and after pH cycling of each sample. Lesion depth were measured (µm) and compared to the enamel thickness to calculate a demineralization index. All groups were compared using the Kruskal Wallis test and Dunn's post-test. Results: PS group showed the lowest demineralization index (0.27 µm) when compared to the control area (0.39 µm) (p<0.05). IC presented a slightly higher percentage of lesions when compared to PS, however, did not differ significantly from the control exposed area. Conclusions: The resin sealant Pro Seal® had a positive protective effect under white spot environmental area and Icon® infiltrant, although showed some protection, did not statistically differ from controls. Key words:Dental Caries, Orthodontics, Dental Enamel, Sealants.
RESUMO
E-waste recycling remains a major source of livelihood for many urban poor in developing countries, but this economic activity is fraught with significant environmental health risk. Yet, human exposure to the toxic elements associated with e-waste activities remains understudied and not evidently understood. This study investigates the impact of informal e-waste processing on the blood lead levels (BLLs) of e-waste workers and non-e-waste workers (mainly females working in activities that serve the Agbogbloshie e-waste site), and relates their lead exposure to socio-demographic and occupational characteristics. A total of 128 blood samples were analysed for lead levels. Surprisingly, the mean BLL (3.54µg/dL) of non-e-waste workers was slightly higher than that of e-waste workers (3.49µg/dL), although higher BLLs ranges were found among e-waste workers (0.50-18.80µg/dL) than non-e-waste workers (0.30-8.20µg/dL). Workers who engaged in e-waste burning tended to have the highest BLLs. In general, the BLLs are within the ABLES/US CDC reference level of 5µg/dL, although 12.3% of the workers have elevated BLLs, i.e. BLL ≥5µg/dL. The study concludes that the impact of e-waste recycling is not limited to workers alone. Traders and residents within the Agbogbloshie enclave are equally at risk through a range of environmental vectors. This calls for increased public awareness about the effects of human exposure to lead and other toxic elements from e-waste recycling. A key contribution is that government and stakeholder projects for safe e-waste infrastructure should disaggregate the e-waste value chain, recognize differential risk and resist one-size-fits-all strategies.
