Three-Dimensional assessment of morphological changes of the maxillary arch: A comparison of two kinds of Palatal Expanders

Objectives: The objective of this study was to analyze the three-dimensional changes resultant from Rapid Maxillary Expansion obtained by two different kinds of appliances; Haas (HA) (tissue-borne) and Hyrax (HY)® (tooth-borne). Methods: Casts were obtained before treatment and after a retention period of 3 months. Both devices were cemented on children, mean age of 11.5 years old. Before and after treatment casts were duplicated and coded. The sample size was 9 HA and 10 HY. 3D measurements of surface distances, total expansion, palatal depth, total area, total volume and first molar tipping, were taken from images obtained with a 3D surface laser scanner (Minolta Vivid 700, MINOLTA, USA). One well-trained operator developed the analytical procedure. T test was used for statistical analysis. Results: The results demonstrated no significant molar tipping in either treatment. There was an increase in all surface distances from before to after expansion, relatively larger on HA casts. Palatal depth was significant decreased for both devices while total area and volume, although increased in both groups, were slightly more increased in the HA. Conclusions: This 3D methodology generated a better visualization of the effects of two different palatal expanders. Molar tipping was not relevant in either treatment, which significantly differs from other studies. The expansion action of these two kinds of appliances affected primarily the posterior region. Both appliances were effective in enlarging palatal area and volume.