Purpose: The purpose of this investigation was to: 1) use the peer assessment rating (PAR), the index of complexity, outcome, and need (ICON), and the American Board of Orthodontics objective grading system (ABO-OGS) indexes to access the quality of orthodontic outcome using temporary skeletal anchorage devices (TSAD) to distalize the mandibular dentition in Class III non-growing patients; 2) to evaluate the dental movement of the mandibular first molars, second premolars, and incisors between subjects; and 3) to identify predictable characteristics in pretreatment subjects that resulted in greater dental movement.
Methods: Subjects were evaluated who finished mandibular arch distalization treatment using TSAD anchorage in the last 5-yrs from the Department of Orthodontics and Dentofacial Orthopedics and Oral Biology at the National Taiwan University. A total of 27 subjects (14 males, 13 females) met this requirement, but only 20 subjects (10 females, 10 males) met our inclusion/exclusion criteria. PAR, ICON, and ABO-OGS indices were recorded on pretreatment and post-treatment dental cast models to evaluate outcomes of orthodontic care. To assess distalization and predictability of distalization, superimposition of pretreatment and posttreatment lateral head films was completed on the Total Interactive Orthodontic Planning System (TIOPS, Denmark). Accuracy of mandibular first molar and second premolar positions was confirmed on occlusalgrams traced from pretreatment and post-treatment dental cast models.
Results: The majority of subjects treated with mandibular arch distalization using TSAD anchorage resulted in successful outcomes as defined by the PAR, ICON, and ABO-OGS indexes. The average treatment time was 28.3 months. The treatment in this subject population resulted in significant changes of the occlusal plane, overjet, maxillary incisor proclination, maxillary to mandibular molar and incisor angulation, nasolabial angle, and upper lip position. All mandibular dental movement was highly significant except for the horizontal and tipping of the mandibular incisors. On average, the mandibular molars were distalized bodily -1.95mm and tipped -6.05 degrees, and the second premolars were distalized -2.27mm and tipped -4.99 degrees. Seven of these subjects experienced greater then 2-mm of molar bodily distalization. It was found that in these seven subjects, distal movement of greater then 2-mm was significantly correlated with before treatment ANB, upper incisor proclination, and maxillary to mandibular incisal angulation.
Conclusion: In a mild Class III non-growing patient, distalization of the mandibular dentition using TSAD anchorage can predictably achieve a successful orthodontic outcome.
