Force distributions associated with different elastic traction methods for maxillary dentition distalization by clear...

The aim of this study was to examine the distribution patterns of orthodontic and reactive forces on each tooth during dentition distalization using clear aligners (CAs), and to assess the impact of different elastic traction methods.

Three sets of aligners for maxillary dentition distalization were fabricated, targeting different tooth movements: simultaneous distalization of the first molars and second premolars; simultaneous distalization of the first premolars and canines; and simultaneous retraction of incisors. An in vitro orthodontic simulator, consisting of 14 three-dimensional sensors, was used to evaluate mechanical changes in each tooth. The orthodontic and reactive forces exerted by aligners, along with additional pulling forces from 1/4 inch 3.5oz elastic using different elastic traction methods (with hooks or buttons), were measured and subjected to comparative analysis.

The initial orthodontic force exerted by CAs varied across different teeth, ranging from 1.52 N to 6.77 N. Concurrently, the primary anchorage teeth experience reactive forces within a range of 1 N to 6.48 N. While the traction force on these teeth generally remained significantly smaller, staying below 0.6 N. The traction force exerted via hooks decayed to 84.3% and was primarily concentrated on the canines, whereas traction force applied via buttons transmitted approximately 96.1% and was more readily distributed to other teeth.

Elastic traction is not sufficient to completely counteract the initial reactive forces produced by the deformation of CAs. It is advisable to use stronger elastics or extend aligner wear time to ensure sufficient anchorage protection. Utilizing traction with buttons can reduce mechanical loss and enhance the transmission of traction force to other teeth.