Condylar volume changes in class II division 2 cases treated with unlocking the mandible using clear aligners

Area of Science:

• Orthodontics
• Craniofacial Biology
• Biomaterials

Background:

• Class II Division 2 malocclusion is characterized by retroclined maxillary incisors and deep overbite.
• Mandibular retrusion often accompanies this malocclusion.
• Treatment involves "unlocking" the mandible via maxillary incisor proclination, deep bite correction, and maxillary expansion.

Purpose of the Study:

• To evaluate three-dimensional changes in condylar volume after using Invisalign® clear aligners to "unlock" the mandible in growing patients with Class II Division 2 malocclusion.
• To determine if Invisalign® treatment influences condylar volume.
• To assess the correlation between condylar volume changes and malocclusion correction.

Main Methods:

• Cone-beam computed tomography (CBCT) data from 22 adolescent patients (11 treatment, 11 control) were analyzed at pre-treatment (T1) and 1.5-2 years post-treatment (T2).
• Dolphin imaging software facilitated cephalometric tracing.
• 3D Slicer and ITK-SNAP software were used to calculate condylar volume.
• Repeated measures ANOVA and Pearson's Correlation Coefficient were employed for statistical analysis.

Main Results:

• Both the treatment and control groups exhibited significant increases in condylar volume from T1 to T2.
• No significant differences in condylar volume were observed between the groups at T1 or T2.
• The change in ANB angle did not correlate with the increase in condylar volume in the treatment group.

Conclusions:

• "Unlocking" the mandible using Invisalign® effectively corrected Class II Division 2 malocclusion.
• Observed condylar volume increases in both groups were likely a result of normal adolescent growth, not the orthodontic treatment.
• Condylar volume changes were not correlated with the degree of malocclusion correction achieved.