What dentition assures oral function?

OBJECTIVE: To evaluate the relationship between dentition and oral function. MATERIAL AND METHODS: A search of the English literature was undertaken using PubMed and appropriate keywords. Citations were identified and hand sorted to confirm their validity against our inclusion criteria. Four specific areas of oral function were addressed; (I) masticatory function, (II) aesthetics, satisfaction and psychosocial ability, (III) occlusal support and stability and (IV) other functionality including tactile perception, phonetics and taste. RESULTS: From an initial pool of 1460 citations, 83 articles met the inclusion criteria. These were summarized and relevant data extracted for incorporation into the review. Masticatory efficiency (assessed as comminution efficiency) and masticatory ability (self-reported) are both linked to the number of teeth. A minimum of 20 teeth with nine to 10 pairs of contacting units (including anterior teeth) is associated with adequate efficiency and ability. Tooth numbers below that level yield impaired masticatory efficiency and are likely to result in reduction in reported masticatory ability. Aesthetics and satisfaction are markedly impaired with loss of anterior teeth. Satisfaction is most likely to be achieved in people who also retain a premolar dentition. Further, there is little increase in satisfaction seen in subjects who retained molar teeth. However, there are marked variations in subjective measures of aesthetics and psychosocial comfort between age groups, social classes, cultures, regions and countries. For most people, occlusal support and stability are obtained with three to four functional posterior units with a symmetrical pattern of tooth loss or five to six units with an asymmetrical pattern. There was no relationship between occlusal factors and symptoms of temporomandibular dysfunction. Phonetics may be maintained even with large anterior restorations. Patients generally attribute a low significance to phonetics, tactile perception and taste compared with mastication and appearance. CONCLUSIONS: The World Health Organization goal for the year 2000, namely to maintain a natural dentition of not less than 20 teeth throughout life, is substantiated by the current literature review as this proposed dentition will assure an acceptable level of oral function.