UCSF

Three Dimensional Analyses of the Effects of Rapid Maxillary Expansion Using Either the Hyrax, Haas or SARPE Approaches

Erik Swanson

PURPOSE

To quantify and understand the immediate and subsequent skeletal and dental effects of rapid maxillary expansion (RME) with either the Hyrax or Haas appliances or Surgically Assisted Rapid Palatal Expansion (SARPE) evaluated by cone beam computed tomography (CBCT).

METHODS

Twenty-three patients (11 Hyrax, 7 Haas, 5 SARPE) were recruited for this study. Patient age was 11-16 years old for the appliance categories and 16-20 years old for the SARPE. Three CBCT scans were taken at specific time points: prior to expansion, immediately following active expansion, and 6 months post-expansion. As a continuation from a previous study, an additional fourth scan was taken 12 months later for the Hyrax group. Multiplanar slices were used to measure: linear transverse dimensions, inclinations of the teeth, and the palatal sutural split.

RESULTS

Analysis confirmed RME increased all transverse dimensions of the maxilla except the external nasal floor. Rapid maxillary expansion also produced differences in the amount of expansion decreasing in magnitude from anterior to posterior. RME led to buccal tipping of posterior teeth in all groups with SARPE having the least amount of tipping. High rates of incidences of bone liabilities were observed in all groups with Hyrax>SARPE>Haas.

CONCLUSION

Rapid maxillary expansion significantly increased transverse dimensions of the maxilla, decreasing in magnitude from anterior to posterior and inferior to superior. Minimal amounts of relapse were observed in all groups due to retention of the expansion with fixed appliances during healing. High rates of incidences of bone liabilities were observed in all groups in both pre-treatment as well as post-treatment images. Repair of bone liabilities were observed in all groups.