In vitro testing of elastomeric modules.

This study describes the in vitro testing of elastomeric modules. Measurements were first made from study models to establish the clinical distance over which modules are used for canine retraction. From this preliminary study, a typodont, banded with 0.018" x 0.025" standard edgewise brackets, was set up with the canine-molar distance at 28 mm. Modules for canine retraction were then fitted by 11 clinicians. The applied force ranged from 125 to 310 g (221 +/- 51 g). A similar, but more extensive study using six different types of modules and two clinician groups (experienced and less experienced clinicians) was then undertaken. Mean force values for different module types ranged from 195 +/- 45 g to 318 +/- 90 g. There was no statistically significant difference between the force values applied by experienced and less experienced clinicians.