A study of the maxillary apical base and its relationship with maxillary dental arch parameters in orthognathic bite

The size of the apical base plays a role in the formation of dental arches and normal occlusion. It is often one of the factors that is implicated in certain orthodontic malocclusions and is essential for determining the treatment plan and the stability of the results.

The aim of this study was to determine the size of the maxillary apical base in orthognathic bite and examine its relationship with some dental arch parameters (surface area, sum of the incisors, frontal arch length and perimeter of the dental arch) using our own diagnostic method.

We studied upper jaw models of 30 untreated subjects of both sexes with orthognathic occlusion of the permanent dentition. A method for obtaining the image of the apical base was developed for this purpose in which orthodontic plaster models were radiographically scanned. Using the Image J software on the scanned X-ray image, we mapped out the outlined area of the apical base and calculated its size.

The mean area of the apical base in the upper jaw in orthognathic bite was 1517.6910 +/- 161.8284 mm2, its adjacent dental arch was 1542.4457 +/- 148.36318 mm2. The mean ratio of the surface area of the dental arch to the apical base area was 1.0180 +/- 0.05833. There was no significant difference between the mean apical base area and the adjacent dental arch. A strong correlation was found between the area of the apical base in the upper jaw and the area of its dental arch, the sum of the incisors, frontal arch length and perimeter of the dental arch.

The preliminary reference data provided by this study for the areas of the dental arch and apical base and their ratios in the upper jaw in orthognathic bite, as well as the established mathematical model for calculating the apical base area can be used for diagnostic purposes and in treatment planning.