Elastomeric Modules Research Articles

Evaluation of friction between ceramic brackets and orthodontic wires of four alloys

The purpose of this investigation was to determine the frictional resistance offered by ceramic brackets used in combination with wires of different alloys and sizes during in vitro translatory displacement of brackets. Findings with ceramic brackets were also compared with outcomes of treatment with stainless steel brackets. Stainless steel, cobalt-chromium, beta-titanium, and nickel-titanium wires of different cross-sectional sizes were tested in medium-twin monocrystalline ceramic brackets with both 0.018-inch and 0.022-inch slot sizes. The wires were ligated into the brackets with elastomeric modules. Brackets were moved along the wire by means of an Instron universal testing machine, and frictional force was measured by a compression cell and recorded graphically on an xy recorder. Wire friction in the ceramic brackets increased as wire size increased, and rectangular wires produced greater friction than round wires. Beta-titanium and nickel-titanium wires were associated with higher frictional forces than stainless steel or cobalt-chromium wires. These findings follow the same general trends as those found with stainless steel brackets; however, wires in ceramic brackets generated significantly stronger frictional force than did wires in stainless steel brackets.

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.

Semi-pneumatic energy absorbing bumper system for motor vehicles

Disclosed is a pneumatic energy absorbing bumper system for interposition between two objects at least one of which is movable including an inflatable elastomeric module means for receiving an external force, support means for mounting said module means to at least one of said objects, means for hermetically sealing the module means to the support means to form a cavity therebetween closed to the atmosphere, and means for permitting selective communication between the cavity and the atmosphere upon the application of an external force of predetermined magnitude to the module means.