Biological and biomechanical perspectives of normal dental occlusion

From a biological or morphological perspective, it has been accepted that normal dental occlusion requires an even and simultaneous contact of all possible teeth. On the other hand, from a biomechanical perspective, normal dental occlusion also requires adequately distributed occlusal loads on the dental arch and axial loading of occlusal force on each tooth. However, the scientific basis for this theory is fairly new, since the actual scheme of normal occlusion was recently put forth by the quantitative analyses of the number, distribution, and intensity of occlusal tooth contacts. These analyses were enabled by two diagnostic systems. The first system consists of an EMG biofeedback trainer and an image-processing device. The former enables the minimization of jaw muscle activities during light tooth tapping. The tooth contact position during the tapping is termed as the "physiological centric position" (PCP) because it is very stable and representative. The latter captures the translucent image of the check-bite, which is taken in the PCP, and quantitatively analyzes the number, position, and distribution of occlusal contacts. The other system is the bite force analyzing system that enables simultaneous recording of forces at multiple occlusal contact points during forceful clenching. In this paper, the author has described an actual scheme of normal dental occlusion based on these systems. The scheme includes parameters such as even and simultaneous contact of all posterior teeth, bilaterally symmetrical distribution of tooth contacts and occlusal loads, and larger and more intense tooth contact of the posterior teeth as compared with the anterior teeth. Based on these parameters, the biological-biomechanical interface of dental occlusion is discussed.