A comparative evaluation of frictional resistance and surface roughness of silver coated and uncoated stainless-steel bracket wire assembly- An in-vitro study

BACKGROUND: Silver ions act as potent antimicrobial agents. Silver coating of brackets and the archwires can help reduce the formation of white spot lesions and caries which is commonly seen with fixed orthodontic treatment. However, this may affect the friction and surface roughness of the bracket-wire assembly which in turn affects the biological tooth movement. MATERIAL AND METHODS: A total of 60 samples were included in the study which was divided into four groups. Group-1: • 15 silver coated 0.022 x 0.028” slot MBT prescription maxillary central incisor brackets • 15 silver coated 0.019 x 0.025” stainless-steel wires; Group-2: • 15 uncoated 0.022 x 0.028” slot MBT prescription maxillary central incisor brackets • 15 silver coated 0.019 x 0.025” stainless-steel wires; Group-3: • 15 silver coated 0.022 x 0.028” slot MBT prescription maxillary central incisor brackets • 15 uncoated 0.019 x 0.025” stainless-steel wires; Group-4: • 15 uncoated 0.022x0.028” slot MBT prescription maxillary central incisor brackets • 15 uncoated 0.019 x 0.025” stainless-steel wires. All brackets and wires used were of American Orthodontics, St. Paul, USA. Surface modification of wires and brackets was carried out using the Vacuum Coating Unit model by Thermal Vacuum Evaporation method with silver nanoparticles (10 nm size). The frictional resistance of all brackets and wires was checked using Universal Testing Machine. RESULTS: On comparison of maximum load, it was found that friction was highest in group 3, followed by group 1, group 4 and group 2. The mean difference between all groups was found to be statistically significant with a P value < 0.05. The Scanning Electron Microscope studies showed that the surface roughness of silver-coated wires and brackets before the friction test was less compared to uncoated wire-bracket assembly. The surface roughness of the bracket and wire after the friction test was as follows: •Bracket roughness: Group 4> Group 1> Group 2> Group 3 •Wire roughness: Group 4> Group 1> Group 2> Group 3. CONCLUSIONS: This study concluded that friction was least when only the wire was coated with silver and the bracket was uncoated and it was the most when the bracket was coated and the wire was uncoated. The surface roughness after the friction test was the least when the wire was uncoated. Key words:Silver nanoparticles, Frictional Resistance, Surface Roughness.