An evaluation of incisal guidance and its influence in restorative dentistry

Abstract

UNCTIONAL COORDINATION of the occluding surfaces of the teeth has been spoken of as one of the most important sciences in the practice of dentistry. The incisal guidance, which is normally the inclination of the lingual surfaces of the six upper anterior teeth, might be considered as the key to a harmonious functional relationship of the natural dentition, or the key to functional occlusion. It might clarify our thinking to outline some differences in our concept of the ideal functional relationship of teeth of the complete denture from that of the natural dentition. In complete dentures, the six upper and six lower anterior teeth seldom make contact in the centric maxillomandibular relation; this contact is not necessary for the most favorable distribution of stress over the maximum denture-bearing area. In the natural dentition, contact of the six upper and lower anterior teeth is most common and is essential for the most favorable distribution of occlusal forces over the maximum number of teeth. In complete dentures, the three point balancing contacts in all eccentric positions, lateral and protrusive, are essential for the maximum functional stability of the dentures and the most favorable distribution of stresses. In the natural dentition, balancing contacts, that is, contacts of the posterior teeth in the protrusive relation, or contact of teeth on the nonfunctioning side in the lateral eccentric relation, seem to be not only nonessential for the most favorable distribution of functional forces, but these balancing contacts are a common contributing cause for the loss of alveolar support about the posterior teeth or for pathology of the temporomandibular joint. It is so extremely difficult to differentiate the nondestructive balancing contacts of the natural dentition from the destructive ones that their elimination would seem to be a reasonable measure of prevention. They should always be eliminated in the treatment of periodontal disturbances of the teeth involved, or of a dysfunction of the temporomandibular joint.