THE EFFECTS OF DIFFERENT SECTIONAL ARCHES IN CANINE RETRACTION

The purpose of the present study was to compare the effects of Gjessin g's canine retraction arch with a sectional arch including a reverse c losing loop, which are both used for canine retraction in extraction c ases. Our study involved both the maxilla and the mandible independent ly. After upper first premolar extractions and levelling of the teeth with 0.018-inch slot standard Edgewise appliances on 12 subjects, with a mean age of 15 years, the right maxillary canines were retracted by 0.016 x 0.022-inch sectional arches including a reverse closing loop, for a mean period of 7.75 months whereas the left maxillary canines w ere retracted by 0.016 x 0.022-inch Gjessing retraction arches for a m ean period of 6.25 months. Following lower first premolar extractions and levelling of the teeth in eight subjects with a mean age of 13 yea rs 7 months, the right mandibular canines were retracted by 0.016 x 0. 022-inch sectional arches with reverse closing loop for a mean period of 7.75 months and the left mandibular canines were retracted by 0.016 x 0.022-inch Gjessing arches for a mean period of 6 months. The prese nt study was carried out on 40 lateral cephalometric films of 20 subje cts taken prior to and at the end of canine retraction. The difference s between the mean changes of the sectional arch including reverse clo sing loop and Gjessing retraction arch groups were found to be statist ically significant for the amount of upper canine crown retraction, me sial movement of upper first molar crown and duration and rate of uppe r canine distal movement. The differences between the two groups were also found to be significant for the distal movement of the apex of th e lower canine root, mesial movement of the apex of the lower first mo lar root, and the duration and rate of canine movement.