Sarocha Poolkerd. In vivo study of orthodontic elastomeric chains for canine retraction. Master's Degree(Orthodontics ). Mahidol University. : Mahidol University, 2009.
In vivo study of orthodontic elastomeric chains for canine retraction
Abstract:
The purposes of this study were: (1) to investigate the force delivery of
elastomeric chains through 28 days of clinical use for canine retraction; (2) to compare
the force delivery between Tuff® and Dynaflex® elastomeric chains; (3) to compare
the force delivery among different study periods from each brand of elastomeric
chains; and (4) to compare the force delivery between the upper and lower arch from
each brand of elastomeric chains. All 32 subjects (12 male, 20 female; mean age 21.4
years) wore the pre-adjusted edgewise appliances in 0.022 х 0.028-inch slot brackets
and passive 0.016 х 0.022 inch stainless steel archwires. Elastomeric chains were used
as the canine retraction force to close symmetrical first premolar extraction sites. The
length of elastomeric chains was used at approximately 70% to 75% of the actual
canine retraction distance (distance between the auxiliary hook of the first molar tube
and the distal aspect of distal wings of the canine bracket). For each subject, Tuff® and
Dynaflex® elastomeric chains were used randomly in different arches and opposing
quadrants (split-mouth study design). All subjects were divided into four groups by
different study periods. Each group consisted of eight subjects. In group A, the force
delivery was measured at initial placement and one hour; after that the elastomeric
chain was changed for a new elastomeric chain and the force delivery was measured at
initial placement and 28 days. In group B, the force delivery was measured at initial
placement and 7 days. In group C, the force delivery was measured at initial placement
and 14 days. In group D, the force delivery was measured at initial placement and 21
days. The results showed that: (1) the mean of force delivery of both elastomeric
chains was in the proper range for canine retraction from 350 grams to 100 grams
through 28 days of study period; (2) The force delivery between Tuff® and Dynaflex®
elastomeric chains was significantly different at initial measurement and there were no
significant differences in other study periods at P value < 0.05; (3) Both elastomeric
chains generated nearly constant force delivery between 14 days to 28 days of the
study period; (4) The force deliveries of each elastomeric chain in the upper and lower
arch were clinically similar.