Effects of maxillary molar distalization with Zygoma-Gear Appliance

Abstract

Objective: To evaluate the dentoalveolar, skeletal, and soft tissue effects of the Zygoma-Gear Appliance (ZGA) when used for bilateral distalization of the maxillary molars.

Materials and methods: The study group included 15 patients (mean age, 15.87 ± 1.09 years; range: 14-18 years) treated with the ZGA system supported with zygomatic anchorage miniplates. The changes due to the distalization were evaluated from the lateral cephalometric films taken before and after distalization by means of a paired t-test.

Results: The mean treatment period required to achieve a Class I molar relationship was 5.21 months. The distalization amount of the maxillary molars was 4.37 ± 2.15 mm (P < .001), and, thus, the rate for the distal movement of the molars was 0.84 mm per month. Maxillary first molars showed a slight intrusion (0.50 mm) (P > .05), while distal tipping was only 3.30° ± 2.31° (P > .05). Furthermore, there was a decrease in overjet (-0.50 mm) (P > .05), indicating that there was no anchorage loss with use of the ZGA.

Conclusions: Maxillary molar distalization without anchorage loss can be achieved in a short time with ZGA.

Figure 1

Zygomatic anchor plate used for distalization.

Figure 2

Modified inner bow used for the distalization.

Figure 3

Schematic illustration of the components of the Zygoma-Gear Appliance.

Figure 4

Intraoral photographs of a patient before (A), during (B), and immediately after (C) the distalization.

Figure 5

Lateral cephalometric radiographs of a patient before (A) and immediately after (B) the distalization.

Figure 6

Soft tissue and angular skeletal measurements: (1) SNA (°); (2) SNB (°); (3) ANB (°); (4) MP/PP (°); (5) SN/MP (°); (6) FMA (°); (7) SN/PP (°); (8) UL-E (mm); (9) LL-E (mm); and (10) nasolabial angle (°).

Figure 7

Linear skeletal measurements (mm): (1) A point to Nasion perpendicular; (2) Pg point to Nasion perpendicular; (3) N-ANS; (4) ANS-Me; (5) N-Me; (6) S-Go; (7) A-HRL; (8) B-HRL; (9) Pg-HRL; (10) A-VRL; (11) B-VRL; and (12) Pg-VRL.

Figure 8

Linear and angular maxillary and mandibular dentoalveolar measurements: (1) Overbite (mm); (2) Overjet (mm); (3) Wits (mm); (4) U1/PP (°); (5) L1/MP (°); (6) HRL-U1 (°); (7) HRL-U6 (°); (8) HRL-U1 (mm); (9) HRL-U6 (mm); (10) VRL-U1 (mm); and (11) VRL-U6 (mm).

Figure 9

Schematic illustration of the dentoalveolar changes due to the distalization.