Incisal guidance of natural teeth in adults

Incisal guidance is the path on the lingual surface of the maxillary anterior teeth along which the mandibular anterior teeth glide, in neutro- or distoocclusion. If there is anterior contact in mesioocclusion, the lingual surface of the mandibular anterior teeth glides along the incisal edge and/or labial surface of the maxillary anterior teeth. Incisal guidance along with the temporomandibular joints, the related musculature, and the associated neuromuscular mechanisms are important in controlling anterior, posterior, vertical, and sometimes lateral movements of the mandible when the teeth are in contact. An unfavorable incisal guidance contributes significantly to anterior alveolar bone loss and tooth mobility when there are susceptible periodontal tissues and excessive forces. Incisal guidance is the result of four components: (1) horizontal overlap, (2) incisal level, (3) labiolingual curve, and (4) vertical overlap. The horizontal overlap is far more significant than the vertical overlap in influencing the health of the anterior teeth.