Rapid Maxillary Expansion May Improve Condyle-Fossa Relationship and Intercondylar Symmetry

Condylar volume comparison after rapid maxillary expansion by Haas and Hyrax in growing patients: A retrospective cross-sectional study

PURPOSE

This study aimed to evaluate the condylar volume of growing patients after rapid maxillary expansion (RME) by Haas and Hyrax appliances.

METHODS

This retrospective cross- sectional study assessed the records of patients diagnosed with transversal maxillary deficiency and with incomplete maturation of midpalatal suture. RME was performed with Haas or Hyrax appliances. Condylar volume was obtained by segmentation of DICOM images from cone-beam computerized tomographys before (T1) and after one year (T2) of RME. The results were compared between the experimental times, sex, and appliances by parametric tests (alpha=5%).

RESULTS

Twenty-seven patients were included (128±21 months old). There were no statistical differences in condylar volume between experimental times (T1 and T2), sex, and appliances to the right and left condyle (P>0.05).

CONCLUSION

RME by Haas or Hyrax does not impact the condylar volume of growing patients.

Analysis of changes and correlation in condyle-fossa relationship after maxillary skeletal expansion

OBJECTIVE

To investigate the changes in condyle-glenoid fossa relationship after maxillary skeletal expansion (MSE) and to verify the correlation between the condyle positional changes and expansion effect.

METHODS

In this study, 20 patients (mean age 21.1 ± 5.7 years, 8 male, 12 female) with maxillary transverse deficiency (MTD) were treated with the MSE appliance, which contained molar bands and a expander with four micro-implants. The CBCT images were taken before expansion (T0), after expansion (T1) and after 6 months of maintenance (T2). The posterior TMJ space (PS), superior TMJ space (SS), anterior TMJ space, coronal lateral TMJ space (CLS), coronal medial TMJ space (CMS), condyle axis angle, maxillary basal bone width (BWM), inter-molars width, nasal bone width, molar inclination and molar palatal cusp height (U6H) were measured using Dolphin Imaging.

RESULTS

At T1, compared with T0, the PS and SS significantly increased by 0.41 mm (P = .008) and 0.3 mm (P = .007). But only the SS significantly increased by 0.21 mm (P = .025) at T2. There was a significant difference of 0.37 mm (left-right, P = .014) between the left and right SS at T0, but no significant difference at T1 and T2. The increased BMW showed weak positive correlations with the change of PS (P = .015) and CMS (P = .031), and the decreased U6H showed weak negative correlations with the change of PS (P = .015) and CLS (P = .031) at T1.

CONCLUSIONS

The use of MSE led to an increase in the SS and PS, which were weakly correlated with BWM and U6H. But this effect in the TMJ space gradually diminished after 6 months of maintenance, and the symmetry of the condyle-fossa relationship was preserved.