An Active,Skeletally Anchored Transpalatal Appliance for Derotation,Distalization and Vertical Control of Maxillary First Molars

Abstract

Objective

The objective of this investigation was to evaluate treatment outcomes of the skeletally anchored ‘Frog’ appliance.

Design

A single-centre, retrospective study was performed.

Setting

Private orthodontic practice.

Participants

Patients who had undergone comprehensive orthodontic treatment with the skeletally anchored ‘Frog’ appliance.

Methods

43 participants (20 males and 23 females) who had received treatment with the skeletally anchored ‘Frog’ appliance where included. In order to explore dentoalveolar and skeletal treatment outcomes, pre- (T1) and post- (T2) treatment measurements were performed on patients’ plaster models and cephalometric images. Comparisons between T1 and T2 were made by means of a Student's t-test. All statistical analyses were conducted at the 0·05 level of statistical significance.

Results

Study model analysis revealed a statistically significant derotation of maxillary molars (μ_ΔT2−T1 = 9·5°, P<0·001) as well as an increase in transverse arch dimensions at the end of treatment (μ_ΔT2–T1 = 2·2 mm, P<0·001). Cephalometric changes included bodily distalization of maxillary molars (μ_Δ(T2–T1) = −1·9 mm, P<0·001), as well as noticeable angular displacement (μ_ΔT2–T1 = 4·1°, P = 0·004). No significant anchorage loss was observed, as displayed by the limited change in maxillary incisor position (μ_Δ(T1–T2) = 0·2 mm, P = 0·45). In addition, excellent vertical control of the maxillary molars was achieved, with no change in the mandibular plane (ML/NSL) angle (μ_ΔT2–T1 = 0·3°, P = 0·38).

Conclusions

The skeletal ‘Frog’ is effective in derotating and distalizing maxillary molars without anchorage loss and with excellent vertical control.