# A comparative three-dimensional analysis of skeletal and dental changes induced by Herbst and PowerScope appliances in Class II malocclusion treatment: a retrospective cohort study

## TL;DR

This study compares two appliances for correcting jaw misalignment, finding that one causes more skeletal changes while the other causes more dental changes.

## Contribution

A 3D comparative analysis of skeletal and dental outcomes between Herbst and PowerScope appliances in Class II malocclusion treatment.

## Key findings

- Herbst appliances caused greater anterior displacement at B-point and Pogonion compared to PowerScope.
- PowerScope resulted in reduced SNA angle while Herbst increased SNB angle, indicating different skeletal effects.
- Herbst led to less lower incisor proclination and more upper incisor distal movement compared to PowerScope.

## Abstract

Skeletal Class II malocclusion is commonly treated using mandibular advancement appliances during growth. Evaluating the comparative effectiveness of different appliances can help optimize treatment outcomes.

This study aimed to compare dental and skeletal outcomes of Class II malocclusion treatment using Herbst and PowerScope appliances in conjunction with fixed orthodontic therapy.

This retrospective comparative study included 46 consecutively treated patients in two university clinics: 26 with PowerScope and 20 with Herbst MiniScope. CBCT scans were obtained before and after treatment. Skeletal and dental changes were analyzed using maxillary and mandibular voxel-based regional superimpositions and cranial base registrations, aided by AI-based landmark detection. Measurement bias was minimized through the use of a calibrated, blinded examiner. No patients were excluded from the analysis. Due to the study’s retrospective nature, no prospective registration was performed; the institutional review board granted ethical approval.

The Herbst group showed greater anterior displacement at B-point and Pogonion than PowerScope (2.4 mm and 2.6 mm, respectively). Both groups exhibited improved maxillomandibular relationships, with PowerScope’s SNA angle reduced and Herbst’s SNB increased. Vertical skeletal changes were observed at points A, B, and Pog in both groups. Herbst also resulted in less lower incisor proclination and more pronounced distal movement of upper incisors.

Both appliances effectively corrected Class II malocclusion. Herbst promoted more pronounced skeletal advancement, while PowerScope induced greater dental compensation. These findings may be generalizable to similarly aged Class II patients in CVM stages 3–4.