Quantitative evaluation of the effect of bolus size and number of chewing strokes on the intra-oral mixing of a two-colour chewing gum.

One of the major aims of the dental profession is the maintenance of oral function, specifically chewing ability. However, there are no generally accepted measures of chewing ability or even general agreement as to what level of tooth loss is deemed to require clinical intervention. There is therefore a need for simple objective tests of oral function. In this study a modification of the two-colour chewing gum test devised by Liedberg & Owall (1991, 1995) is described. In this test chewing gum containing two contrasting colours is chewed. On removal from the mouth the bolus is placed in a transparent plastic bag, flattened and a digital image is taken. Several image processing techniques are described and evaluated as measures of the amount of mixing present in the chewed gum. Flattening the gum was found to increase the accuracy of subjective evaluation, which was similar to that achieved by the image processing techniques.