Force decay of orthodontic elastomeric chains by using three different mechanisms simulating canine retraction

الملخص EN

Background : The ideal force-delivery system must: provide optimal tooth moving forces that elicit the desired effects, be comfortable and hygienic for the patient, require minimal operator manipulation and patient cooperation and provide rapid tooth movement with minimal mobility during orthodontic therapy, the elastomeric chains have the greatest potential to fulfill these requirements. Materials and Methods : This in vitro study was designed to determine the effect of three different mechanisms for canine retraction : (6-3 , 6-5-3 and chain loop ) on the load relaxation behavior of three types of elastomeric chains : (maximum clear , maximum silver and extreme silver) from the same company (Ortho Technology company) with two different brand configurations: closed loop and open (short filament) chains under effect of time at (zero time, 24hr., 7, 14 , 21 and 28 days) in artificial saliva. Results : Statistical analysis showed that there was a highly significant difference in the mean percentage force decay for the three different mechanisms (P≤ 0.001).For all the three types, the 6-3 mechanism had the smallest mean percentage force decay.

There was a highly significant difference in the mean percentage force decay for the different types (P ≤ 0.001).

For all three mechanisms, extreme silver elastomeric chains had the smallest percentage force decay while maximum silver elastomeric chains had the highest percentage force decay. Conclusion : This study illustrated that for all the three types of elastomeric chains, the (6-3) mechanism had the smallest mean percentage force decay.

This finding suggests that it may be most efficient to retract a canine utilizing elastomeric chain directly from the molar hook to the canine bracket.

The chain loop mechanism may not be indicated for space closure in vivo due to the excessive physiological force values involved with this mechanism.