Evaluation of Maxillary Molar Distalization Supported by Mini-Implants with the Advanced Molar Distalization Appliance (amda®): Preliminary Results of a Prospective Clinical Trial

Abstract

Background: Class II is considered one of the most common malocclusions, influencing 37% of schoolchildren in Europe and 33% of orthodontic patients in the United States. When this type of malocclusion is combined with increased overjet with proclined teeth and maxillary excess, then moving maxillary molars distally is suggested. According to the recent literature, modern appliances that lack patient cooperation can be combined with temporary anchorage devices to provide absolute and skeletal anchorage while supporting the non-compliance appliances to eliminate their side effects, such as anterior and posterior anchorage loss along with maxillary molar inclination and rotation. To counteract these limitations, the Advanced Molar Distalization Appliance (amda^®), a non-compliance appliance for maxillary molar distalization supported by two mini-implants (MIs) with anterior abutments, was recently developed. Methods: In this preliminary prospective clinical trial, eight consecutive patients treated with the amda^® are evaluated through lateral cephalometric radiographs, while its application, construction, and anchorage is presented and discussed. The evaluation of dentoalveolar and skeletal changes has been made with 14 variables measured on the pre- and post-cephalometric radiographs before and immediately after maxillary molar distalization (T₀ and T₁, respectively), along with cephalometric superimpositions by the structural method. Results: In total, the mean distal molar movement was 4.2 ± 1.37 mm, the mean distal tipping was 1.7 ± 1.9 degrees, and the vertical movement was 1.6 ± 2.6 mm. Conclusions: The amda^® seems to provide an ideal option for treating patients with Class II malocclusion, achieving bodily movement of the maxillary molars with only minimal distal tipping and no anchorage loss.

Keywords: Class II malocclusion; amda®; distalization; mini-implants; non-compliance appliances.

Figure 1

The amda^® on two mini-implants (2.0 × 10 mm; Tomas Pin EP; Dentaurum, Germany).

Figure 2

Two mini-implants were placed in the paramedian region. Transferred caps placed on the two mini-implant heads.

Figure 3

Mini-implant analogs were placed into the alginate impression to deliver to the laboratory. The amda^® in a plaster cast model with bands and lab analogs adjusted.

Figure 4

Placement of two mini-implants through the gingival tissue in the paramedian region of the palate, 3–6 mm from the midpalatal suture and 3–6 mm posterior to the incisive foramen. Figure taken with permission from Papadopoulos, M.A. (Ed.) Skeletal Anchorage in Orthodontic Treatment of Class II Malocclusion; Elsevier, Mosby: Edinburgh, UK, 2015 [14].

Figure 5

(A) The constructed centroid point of the maxillary first molar. (B) Cephalometric dentoalveolar linear measurements. (C) Cephalometric dentoalveolar angular measurements. Figure taken with permission from Papadopoulos MA, Melkos AB, Athanasiou AE [6].