Three-dimensional assessment of the relative position of the roots of the teeth in the anterior lower jaw for treatment planning for class III occlusion anomalies using mini-implants

Relevance. The use of skeletal support in orthodontics led to the use of elastic traction and mini-implants for upper jaw traction in class III treatment, however, when planning the placement, clinicians did not take into account the anatomical structures of individual areas, that could lead to iatrogenic damage to the endodontium and periodontium.

The aim of this study is a three-dimensional assessment of the relative position of the roots of mandibular canines and incisors when planning treatment for anomalies of class III occlusion using mini-implants.

Materials and methods. We examined 27 cone beam computed tomography (CBCT) scans in patients aged 20 to 36 years. First, the divergence angle of the longitudinal axes of the canines and lateral incisors was measured on coronary sections of CBCT. Then, according to the bisector of the angle from the anatomical cervix of the tooth, the distances between the roots were measured at the following points: 3 mm, 5 mm, 8 mm and 10 mm. Similar measurements were performed between the central incisors.

Results. The average divergence angle between the lateral incisor / canine on the right was 13.8 ± 2.82 degrees, between the lateral incisor / canine on the right 14.68 ± 2.68 degrees and 10.76 ± 2.47 degrees. The average distance between the lateral incisor / canine totaled 2.45 ± 0.4 mm at a level of 5 mm, at a level of 8 mm this distance is 2.9 ± 0.5 mm, and at a level of 10 mm – 3.26 ± 0. 6 mm.

Conclusion. The mini-implant placement in mandibula in the area between the roots of lateral incisors and canines should be carried out more apically from the anatomical cervix of the tooth more than 8 mm.

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