Image processing techniques for assessment of dental trays

A tray selected for the dental patient must adapt to the curvature of the teeth and allow the impression material to be in appropriate thickness everywhere. Generally, the impression trays are selected by the practitioner via testing them in the mouth. The present study was conducted to develop an automated technique for the selection of an appropriate tray for the patient. This technique was used for the alignment of six brands of perforated metal trays with 170 lower arch cast models collected from patients having Angle Class I type occlusion with minor malocclusions. The cast models and trays were scanned into a computer and critical points of casts and skeleton of the tray bases were collected. After alignment of casts and trays using a distance based alignment routine, the trays which most adopted the curvature of the casts were evaluated using the residual distance of alignment The alignment was repeated for selected subsets of the points and minimum point set that is necessary for identification of the correct tray was identified. This method can be used in a routine setting eliminating trial and error or to design better trays to fit the needs of a given population.