Investigation of the association between vertical skeletal patterns and the timing of failure of temporary anchorage devices

Abstract

Temporary anchorage devices (TADs) have become increasingly popular as orthodontic treatment measures for anchorage or distal movement of molars. However, TAD failure is a major limitation, and the aim of this study was to examine the effects of various factors on the timing of TAD failure. This study included 467 TADs implanted on the buccal side of the molar region in 197 patients undergoing orthodontic treatment. The relationship between failure and sex, age, jaw (maxilla or mandible) , side (left or right) , Frankfort mandibular plane angle (FMA) , point A-nasion-point B angle (ANB) , overbite, and overjet was examined. The time (number of days) until failure was also investigated. The failure rates were significantly higher in men compared to women (23.9％ vs. 13.6％ ; p-value ＝ 0.024) , and in the mandible compared to the maxilla (28.2％ vs. 11.8％ ; p-value ＜ 0.001) . A significant difference by agegroup was also observed (p-value ＜ 0.029) , with the failure rates being highest among patients aged ≥ 30 years (29.8％) . Approximately half (47.6％) of the maxillary failures occurred by day 120, and more than half (58.1％) of the mandibular failures occurred by day 60. Moreover, the failure rate by day 120 was higher in the maxilla when the FMA was smaller. The failure rates of TADs implanted on the buccal side of the molar region were influenced by sex, age, and location (i.e., mandible or maxilla) . Failure tended to occur more rapidly and readily in mandibular compared to maxillary implants. Moreover, when considering the vertical skeletal pattern, failure rates ＜ 120 days after implantation tended to increase when the FMA decreased.

The Orthodontic Mini-Implants Failures Based on Patient Outcomes: Systematic Review

“…34 Meanwhile, the result of Kim et al study to evaluate the failure rate of orthodontic mini-implants in the implant failure rate (IFR) and patient failure rate (PFR) showed that IFR and PFR were higher in men than women, although the difference was not significant. 13 Similar to the others, Yoshida et al 35 and Malik et al 25 study also showed that the failure rates of implant were significantly higher in males compared to females. According to Ono et al, the cortical bone between first molar and the second premolar is often the site of implantation thicker in men than in women.…”

“…Xin et al 36 conclude that younger people with removable appliances that implant inserted in the retromaxillary or retromandibular regions had a higher progressive susceptibility to loosening, while the result of Yoshida et al 35 study showed that the failure rate was highest among patients aged more than or equal to 30 years compared to less than 20 years group.…”

“… 33 The higher failure rate in men may be related to anatomic and hormonal differences 34 and the presence of thicker and denser cortical bone, leading to the application of excess torque during implantation. 35 …”

“…This may be related to variations in bone structure such as alveolar cortical bone thickness and mineral density. 35 …”

“…22 Similar to Aly et al, the results of Chang et al study on 840 patients with mandibular buccal shelf miniscrews showed that failure occurred in patients with a mean age of 14 AE 3 years, which was below the overall mean age (16 AE 5 years). 65 Xin et al 36 conclude that younger people with removable appliances that implant inserted in the retromaxillary or retromandibular regions had a higher progressive susceptibility to loosening, while the result of Yoshida et al 35 study showed that the failure rate was highest among patients aged more than or equal to 30 years compared to less than 20 years group. Some studies reported that a greater failure rate generally occurs at a younger age because they have less dense cortical bone, where bone quality is a major factor in the success of orthodontic mini-implants.…”