Abstract:
Compares the mechanical properties comprising ultimate tensile strength, fracture strength, yield strength, percentage elongation and toughness of surface-treated bands and those of untreated orthodontic bands. Samples were the biggest size of lower right molar bands drawn from two manufacturing companies. Bands from the first company were photoetced and non-photoetched orthodontic bands. Bands from the second company were sandblasted and non-sandblasted orthodontic bands. Each sample was cut and rolled by Hydrolic press at 10 Newton prior to cutting into the standard form for tensile test by wire cut technique. Each of standard form of band was examined under stereomicroscope for finding the defect due to wire cut technique. Thirty pieces of the bands in each group were selected by purposive random sampling for tensile test. The aforementioned properties of each band were the recorded by Lloyd universal testing machine. The differences in mechanical properties between the two kinds of band were evaluated by students t-test at 0.05 significant level. The results indicate that the photoetched band has significant higher ultimate tensile strength (635.87 Mpa), yield strength (290.40 Mpa), toughness (335.25 J/m3) and percentage elongation (61.85%) than those of the non-photoetched band. Whereas the sandblasted band has significant lower toughness (231.60 J/m3) and percentage elongation (59.10%) than those of non-sandblasted band. In conclusion surface treatment procedure for increasing retention of the band has effects some mechanical properties under tensile test