RESUMO
Obesity and dental caries are increasingly widespread pathologies. The former is growing so rapidly that the WHO classified its trend as an "epidemic". Both are triggered by a number of well known common etiologic factors sharing also the high added sugar amount since childhood. Because of its fermentation and pH lowering, dietary sugar allows the cariogenic bacteria to damage the tooth enamel provoking the carious lesions. WHO guidelines recommend reducing sugar intake to 10% of the total daily energy need, and highlight that there is evidence which suggests cuttingthis value down to 5% at least. The American guidelines addressing paediatric age put the limit to 25gr a day with a total ban on sugar in those aged 2 or less.
RESUMO
Orthodontic treatment is strongly dependent on the loads developed by metal wires, and the choice of an orthodontic archwire should be based on its mechanical performance. The desire of both orthodontists and engineers would be to predict the mechanical behavior of archwires. To this aim, Gum Metal (Toyota Central R&L Labs., Inc.), TMA (ORMCO), 35°C Copper NiTi (SDS ORMCO), Thermalloy Plus (Rocky Mountain), Nitinol SE (3M Unitek), and NiTi (SDS ORMCO) were tested according to dynamic mechanical analysis and differential scanning calorimetry. A model was also developed to predict the elastic modulus of superelastic wires. Results from experimental tests have highlighted that superelastic wires are very sensitive to temperature variations occurring in the oral environment, while the proposed model seems to be reliable to predict the Young's modulus allowing to correlate calorimetric and mechanical data. Furthermore, Gum Metal wire behaves as an elastic material with a very low Young's modulus, and it can be particularly useful for the initial stage of orthodontic treatments.
