Analysis of pretreatment factors associated with stability in early class III treatment

Radiographic Imaging for the Diagnosis and Treatment of Patients with Skeletal Class III Malocclusion

Skeletal Class III malocclusion is one type of dentofacial deformity that significantly affects patients' facial aesthetics and oral health. The orthodontic treatment of skeletal Class III malocclusion presents challenges due to uncertainties surrounding mandibular growth patterns and treatment outcomes. In recent years, disease-specific radiographic features have garnered interest from researchers in various fields including orthodontics, for their exceptional performance in enhancing diagnostic precision and treatment effect predictability. The aim of this narrative review is to provide an overview of the valuable radiographic features in the diagnosis and management of skeletal Class III malocclusion. Based on the existing literature, a series of analyses on lateral cephalograms have been concluded to identify the significant variables related to facial type classification, growth prediction, and decision-making for tooth extractions and orthognathic surgery in patients with skeletal Class III malocclusion. Furthermore, we summarize the parameters regarding the inter-maxillary relationship, as well as different anatomical structures including the maxilla, mandible, craniofacial base, and soft tissues from conventional and machine learning statistical models. Several distinct radiographic features for Class III malocclusion have also been preliminarily observed using cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI).

Influence of differences in mandibular incisor inclination on skeletal stability after orthognathic surgery in patients with skeletal Class III malocclusion

OBJECTIVE

The preoperative inclination angle of mandibular incisors was crucial for surgical and postoperative stability while the effect of proclined mandibular incisors on skeletal stability has not been investigated. This study aimed to evaluate the effects of differences in presurgical mandibular incisor inclination on skeletal stability after orthognathic surgery in patients with skeletal Class III malocclusion.

METHODS

A retrospective cohort study of 80 consecutive patients with skeletal Class III malocclusion who underwent bimaxillary orthognathic surgery was conducted. According to incisor mandibular plane angle (IMPA), patients were divided into 3 groups: retroclined inclination (IMPA < 87°), normal inclination (87° ≤ IMPA < 93°) and proclined inclination (IMPA ≥ 93°). Preoperative characteristics, surgical changes and postoperative stability were compared based on lateral cephalograms obtained 1 week before surgery (T0), 1 week after surgery (T1), and at 6 to 12 months postoperatively (T2).

RESULTS

The mandible demonstrated a forward and upward relapse in all three groups. No significant differences in skeletal relapse were observed in the 3 groups of patients. However, the proclined inclination group showed a negative overbite tendency postoperatively compared with the other two groups and a clinically significant mandibular relapse pattern. Proclined IMPA both pre- and postoperatively was correlated with mandibular relapse.

CONCLUSION

Sufficient presurgical mandibular incisor decompensation was of crucial importance for the maintenance of skeletal stability in patients with skeletal Class III malocclusion who subsequently underwent orthognathic surgery.

Long-term skeletal and dentoalveolar effects of hybrid rapid maxillary expansion and facemask treatment in growing skeletal Class III patients: a retrospective follow-up study

BACKGROUND

Regardless of the treatment protocol, stability in Class III patients always represents a major concern. The aim of this study was to assess the short and long-term skeletal and dentoalveolar modifications in a group of class III patients treated with hybrid rapid maxillary expander (RME) and facemask (FM). Indeed, no long-term studies have been conducted yet with the objective of evaluating the effects of this kind of approach when applied to patients who have already gone thought their peak of growth.

MATERIAL AND METHODS

27 patients with skeletal Class III malocclusion were treated using hybrid RME according to alternating rapid maxillary expansion and constriction (ALT-RAMEC) protocol, followed by 4 months of facemask therapy. After the orthopaedic phase, each patient underwent orthodontic treatment with fixed multibracket appliances. A mean follow-up of 7 years, 10 months was performed. Pre-treatment (TO), post-treatment (T1) and follow up (T2) cephalometric tracing were analysed, comparing dental and skeletal measurements.

RESULTS

Point A advanced by a mean of 3.5 mm with respect to VerT, then relapsed by 0.7 in the post-facemask period, thereby yielding of a mean advancement of 2.7 at T2. The sagittal relationship significantly changed after RME + facemask protraction (3.8° of ANB and 5.189 mm of Wits). Although both Wits and ANB values worsened over time, the improvement from T0 is still appreciable at T2.

CONCLUSION

Despite the physiological relapse due to mandibular growth, the long-term cephalometric follow-up confirms the maintenance of all positive outcomes of the previous orthopaedic treatment with hybrid RME and facemask.