Remodelling of the palatal dome following rapid maxillary expansion (RME): laser scan-quantifications during a low growth period.

OBJECTIVES

To evaluate changes in the palatal vault after rapid maxillary expansion (RME) with bonded splint appliances.

SETTING AND SAMPLE POPULATION

The sample comprised 24 children (12 boys and 12 girls) with mixed dentition (mean age 8.3 years; range 6.4-10.4 years).

MATERIALS AND METHODS

Following expansion, the splint appliance was used as a retainer for 6 months and then removed. Study casts were taken before RME (T0) and when the appliance was removed (T1). Then, 3D laser scans were taken to build complete 3D jaw models. Frontal cross sections were constructed at 53-63, 55-65 and 16-26, exported as coordinates, and finite element calculated to quantify their area, width and height. Maxillary length was also determined.

RESULTS

Paired t-tests indicated statistically significant increases in the average palatal width (T1-T0=6.53-6.79 mm) and cross-sectional area (T1-T0=20.39-21.39 mm2) after RME (p<0.001). However, small but statistically significant reductions were observed in palatal height (T1-T0=-0.49 mm, only at 55-65; p<0.001) and length (T1-T0=-0.54 mm; p<0.01). Linear regression analysis showed statistically significant (p<0.001) direct correlations between the widths and respective cross-sectional areas. Age did not influence any measurement. The reliability of the measurements was examined with an intraclass correlation coefficient (ICC). We found an ICC>0.99 (p<0.001) for all tested parameters.

CONCLUSIONS

Rapid maxillary expansion distinctly increased mean palatal widths and cross-sectional areas. However, palatal height (55-65) and maxillary length decreased to a small extent.