Comparison of Occlusion Settling in Orthodontic Patients after Using Essix and Hawley Retainers by T-Scan III

Occlusion stability following orthodontic treatments is a daunting challenge for orthodontists and this stability is maintained using retainer devices after the active phase of treatments. Although Hawley retainer has a wide application in retention objectives, the use of Essix retainers has been on a rise in recent years. The present study aimed to compare occlusal settling in orthodontic patients after using Essix and Hawley retainers using the T-Scan III technique for bite recordings in the retention period.

In this observational-analytical trial, 46 orthodontic patients (24 for Hawley and 22 for Essix retainers) were selected at the end of the active phase of the treatment. The patients used Hawley and Essix retainers at both jaws for 1 year, and the occlusal settling (occlusal contacts) was recorded by the T-Scan III technique at the initial time (T0), as well as 6 months (T1) and 1 year (T2) after retention. The intragroup and intergroup changes (percent) that occurred in occlusal contacts in different time intervals were statistically analyzed by paired t-test and student t-test, respectively.

In the Hawley retainer group, the occlusal contacts significantly increased in the posterior teeth (7.708±13.5; P=0.008) and significantly decreased in the anterior teeth (7.416±11.791; P=0.005). On the other hand, in the Essix retainer group, occlusal contacts decreased in the posterior teeth (10.19±14.884; P=0.008) and significantly increased in the anterior teeth (10.381±18.591; P=0.005). 

AS evidenced by the obtained results, both Hawley and Essix retainers caused changes in the occlusal contacts and relative vertical movement of posterior teeth in the patients after 6 months and 1 year of retention, compared to the initial time. Nonetheless, Hawley retainer seemed to ring about more posterior changes (settling) than Essix retainer. Due to the increase in posterior tooth contact and the decrease in anterior tooth contact with the use of Holly retainer, this retainer can be a better choice in deep bite cases. Furthermore, due to the reduction of posterior contacts in the first 6 months in the Essix license plate, it is suggested that the full-time use of this retainer be shortened.