Analysis of chewing movement using elliptic Fourier descriptors

Mandibular kinesiography measures and records the plot of jaw movements in the three spatial planes; this technique not only offers to investigators information about the dynamics of chewing, but also opens important prospects of quantifying dysfunction. At present, chewing patterns are compared on a qualitative basis only, and their morphologic analysis is not accurate. It is therefore necessary to use suitable mathematical algorithms that can manage the data supplied by modern image analyzers without losing the large amount of information they contain. A mathematical model that, by using a Fourier description of the plots of jaw movements, analyzes and characterizes different chewing classes has been developed. As an example of the possible applications, the variability of the exclusively morphologic aspect of the frontal plane plots of the chewing cycle of some subjects under standard conditions was studied and quantified. A morphologic distance between the Fourier coefficients that characterize each plot and the coefficients of a reference plot was also calculated. On these bases it will be possible to define and measure a "normal" chewing cycle under standard conditions and to make an eventual diagnosis of dysfunctional chewing based on a true morphoquantitative evaluation. Moreover, by deepening the analysis of the more occlusal part of the cycle, the model could aid in the identification of unapparent malocclusions.