Clinical effects of different prescriptions on the inclination of maxillary and mandibular incisors by using passive self-ligating brackets

Abstract

Objective: Controlling the incisal inclination is fundamental in orthodontics. However, the relationship between the inclination prescription and its clinical outcome is not obvious, and the incisal inclination changes generated by different bracket prescriptions were investigated.

Methods: Twenty-eight non-extraction dental Class II patients (15 females, 13 males; mean age = 12.9) were retrospectively analyzed. Patients were treated using passive self-ligating fixed appliances with three inclination prescriptions for maxillary incisors (high, standard, low), and two for mandibular incisors (standard, low). Clinical outcomes were compared among different prescriptions, and regression analysis was used to explain the effects of bracket prescriptions and to understand the prescription selection criteria (α = 0.05).

Results: For maxillary central incisors, low and high prescriptions were related to linguoversion (p = 0.046) and labioversion (p = 0.005), respectively, while standard prescription maintained the initial dental inclination. Maxillary lateral incisors did not show significant changes. For mandibular incisors, low prescription led to linguoversion (p = 0.005 for central incisors, p = 0.010 for lateral incisors), while standard prescription led to labioversion (p = 0.045 for central incisors, p = 0.005 for lateral incisors). The factors affecting inclination changes were the imposed change and selected prescription, while prescription selection was influenced by the initial dental inclination and initial intercanine distance.

Conclusions: The direction of correction of incisal inclination can be controlled by choosing a certain prescription, but the final inclination may show limited consistency with it. The amount of imposed inclination change was the most relevant predictor of the clinical outcome.

Keywords: Digital models; Incisor; Orthodontic brackets; Tooth movement.

Figure 1

Example of maxillary digital cast analysis, where incisors to second molars were included, and five points were recorded for each tooth (points are highlighted in green).

Figure 2

Comparison between initial inclination (Tin, full box) and final inclination (Tfin, striped box) of maxillary (A) and mandibular (B) incisors in relation to the inclination prescription. Tsel, selected inclination prescription; NS, not significant. *p < 0.05; **p < 0.01.

Figure 3

Low (green), standard (blue), and high (red) inclination prescriptions for maxillary incisors. Correlation between the final inclination (Tfin) and initial inclination (Tin) (A). Correlation between the change in inclination (ΔT) and differential inclination applied (Tsel-Tin) (B). Tsel, selected inclination prescription.

Figure 4

Low (green) and standard (blue) inclination prescriptions for mandibular incisors. Correlation between the final inclination (Tfin) and initial inclination (Tin) (A). Correlation between the change in inclination (ΔT) and differential inclination applied (Tsel-Tin) (B). Tsel, selected inclination prescription.