[COMPARATIVE TRANSVERSAL EVALUATION OF UPPER JAW FOLLOWING RAPID MAXILLARY EXPANSION IN THE MIXED DENTITION PERIOD....

The aim of this study was to assess the dynamics of changes of the transversal dimensions of upper jaw at different levels following rapid maxillary expansion in child cases during the mixed dentition period according to the medium field of view (FOV) of Cone-Beam Computed Tomography (CBCT). Thirty-seven children aged 7 to 12 were included in this study. The median age was 8.9 years. All patients underwent rapid palatal expansion with the appliance for rapid maxillary expansion (RME) according to orthodontic indications. For each case, cone beam computed tomography (CBCT) data was obtained and evaluated before orthodontic treatment and three to six months after completion of maxillary expansion. Determination of anatomical landmarks and linear transversal measurements of the upper jaw at different levels were carried out using the i-CAT Vision software. The transversal dimensions of the upper jaw were measured, the linear dimensions of the width of the dental, alveolar and basal arch were estimated at the molar level, and at the level of the floor of the nasal cavity exectly between the large palatine canals and at the level of pyriform aperture on the CBCT images obtained before treatment and after rapid maxillary expansion. The greatest maxilla transversal expansion was observed on the level of dental arch and pyriform aperture, on average in 7.1% and 6.03% respectively. The smallest increase in the transversal dimensions of the upper jaw after RME was observed on the level of vestibular cortical plate of the first permanent molars as well as on the level of the centre of molar resistance (on average 3.7%). CBCT data makes it possible to reliably assess the dynamics of changes in the transversal dimensions of the upper jaw at different levels during the mixed dentition following RME, as well as to assess the expansion of the upper jaw at the level of the floor of the nasal cavity. This, in turn, can affect the characteristics of the airflow at the nasal level.