Signal Processing of Intraoral Pressure Curves

Human teeth are susceptible to pressure exertion ; the exertion of a constant low force between 0.1 and 0.5 N results in a change in tooth position ( Prof t, 1978 ). Therefore, tooth alignment in subjects who have not undergone orthodontic treatment is a product of an equilibrium of forces exerted on the teeth. Beside pressure from the lips ( Thüer and Ingervall, 1986 ), the cheeks , and the tongue ( Thüer et al. , 1999 ), a rarely considered factor is subatmospheric intraoral pressure. Subatmospheric pressures arise naturally in intraoral compartments, e.g. in the subpalatal space (SPS) and interocclusal space (IOS ; Engelke et al. , 2010 ), and can be measured by a digital measuring instrument ( Fröhlich et al. , 1991 ; Figure 1 ). Pressures are measured within a prede ned time interval, yielding time-dependent pressure curves that can be denoted by p t ( t = 1, . . . , T ). Curves from patients with different forms of malocclusion can be compared by certain characteristics, for example, the average ( Thüer et al. , 1999 ) or maximum ( Kieser et al. , 2008 ) pressure. Further curve characteristics are for example the area under the curve (AUC) and the number of swallowing peaks and plateau phases ( Engelke et al. , 2010 ; Knösel et al. , 2010 ). Statistical s ignal p rocessing m ethods for i ntraoral p ressure