RESUMEN
OBJECTIVE: (1) To evaluate the corrosion resistance of four different orthodontic archwires and to determine the effect of 0.5% NaF (simulating high fluoride-containing toothpaste of about 2250 ppm) on corrosion resistance of these archwires. (2) To assess whether surface roughness (Ra) is the primary factor influencing the corrosion resistance of these archwires. MATERIALS AND METHODS: Four different archwires (stainless steel [SS], nickel-titanium [NiTi], titanium molybdenum alloy [TMA], and ion-implanted TMA) were considered for this study. Surface characteristics were analyzed using scanning electron microscopy, atomic force microscopy (AFM), and energy dispersive spectroscopy. Linear polarization test, a fast electrochemical technique, was used to evaluate the corrosion resistance, in terms of polarization resistance of four different archwires in artificial saliva with NaF concentrations of 0% and 0.5%. Statistical analysis was performed by one-way analysis of variance. RESULTS: The potentiostatic study reveals that the corrosion resistance of low-friction TMA (L-TMA) > TMA > NiTi > SS. AFM analysis showed the surface Ra of TMA > NiTi > L-TMA > SS. This indicates that the chemical composition of the wire is the primary influential factor to have high corrosion resistance and surface Ra is only secondary. The corrosion resistance of all wires had reduced significantly in 0.5% acidic fluoride-containing artificial saliva due to formation of fluoride complex compound. CONCLUSION: The presence of 0.5% NaF in artificial saliva was detrimental to the corrosion resistance of the orthodontic archwires. Therefore, complete removal of residual high-fluorinated toothpastes from the crevice between archwire and bracket during tooth brushing is mandatory.
RESUMEN
BACKGROUND: The various soft tissue traits that contribute to an aesthetically pleasing face. This should be considered during orthodontic treatment. The aim of the present study was to propose soft tissue norms for Central Indian (Malwa) female population. MATERIALS AND METHODS: Facial photographs of 78 patients of age group 18-26 years were taken in Department of Orthodontics, Rau, Indore, which were then subjected to a selection process and 30 top scorers (30 females) were selected. Lateral cephalograms of individuals were taken and soft tissue profile as well as related osseous and dental structures standard tracing were made on the acetate matte tracing paper. Then eighteen soft tissue traits were studied as described by Bergman. RESULTS: The present study showed that, a mild convexity of the face and the resulting tendency toward Class II in females is acceptable esthetically. A fuller upper lip is considered balanced and esthetic. Increase in lip incompetency is considered unaesthetic. CONCLUSION: A mild convexity of the face and the resulting tendency toward Class II in females is acceptable esthetically. Individual norms are necessary for a population in order to plan and deliver quality treatment.
