How Similar are the Dentoskeletal Characteristics of Class III Double-Jaw Surgery Patients with Ideal Post-Treatment Profiles and Class I Subjects?

Abstract

Objective: To define the dental and skeletal characteristics of Class III surgery patients with ideal final soft-tissue profiles, and to compare them with those of Class I subjects. Also, to show how soft-tissues respond to surgical jaw movements and contribute to the outcome.

Methods: This short-term, retrospective study was conducted using pre-treatment (T0), pre-surgery (T1), and post-treatment (T2) records of 50 double-jaw Class III surgery patients who presented with ideal cephalometric characteristics in sagittal (Holdaway and soft-tissue convexity angles) and vertical dimensions (GoGn. SN angle and upper-to-lower face harmony) at the end of treatment, and 50 control subjects.

Results: At T2, the horizontal distance between the vertical reference plane (a perpendicular plane to the horizontal reference plane that is angulated 7° clockwise to the SN plane) and hard-tissue A, B and Pog points, lower lip, soft-tissue B, and pogonion points were greater, Wits appraisal was more negative, U1.PP was higher, IMPA was lower, and soft-tissue chin (Pog-Pog') was thicker in Group 1 when compared to Group 2 (p<0.05). Moreover, upper lip and subnasal (A-A') thicknesses were decreased, and chin thickness (Pog-Pog') was increased significantly (p<0.05).

Conclusion: Dentoskeletal characteristics of an ideally-treated Class III surgery patient differed from a Class I subject concerning a protrusive maxilla and soft-tissue pogonion, and incisors that were not fully-decompensated. Soft-tissues hindered the actual surgical correction to 66% and 73% in the mid- and lower-faces, respectively.