Tooth Contacts During Mandibular Movement

When depicting the occlusal contact points in detail, it is essential to view these contacts in articulation or establish the paths they follow during mandibular movement. The articular movements of the centric stops run on precisely fixed occlusal guidance paths of their antagonists (Fig 7-30).

During protrusive movement, the working cusps with their centric stops slide out of their analogous contact areas, the approximal marginal ridges or central fossae, in the central developmental groove in a sagittal direction. The movement paths tend to point distally in the mandible and mesially in the maxilla.

In lateral movements, the movement paths must be regarded separately for the working and nonworking sides for both the maxilla and the mandible. On the working side in the maxilla, the centric stops of the antagonizing cusps slide out of the contact areas via the approximal furrows or the buccal notches of the molars in a vestibular direction (Fig 7-31). The occlusal guidance paths are the palatally directed oblique surfaces of the triangular ridges of the buccal cusps.

• The buccal cusps of the mandibular premolars and the mesiobuccal cusps of the mandibular molars slide in a vestibular direction in the ap-proximal marginal ridges of the maxillary teeth; contact is not lost until there is a wide deflection of movement.
• The distobuccal cusps of the mandibular molars slide out of the central fossae along the main developmental groove on the triangular ridges of their antagonists in a vestibular direction. On the working side in the mandible, the centric stops of the antagonizing cusps slide out of the contact areas, such as approximal furrows or the central fossae, in a lingual direction (Fig 7-32). The occlusal guidance paths in the mandible are on the buccal oblique surfaces of the triangular ridges of the lingual cusps.
• The palatal cusps of the maxillary premolars and the distopalatal cusps of the maxillary molars slide in the approximal marginal ridges of the mandibular teeth in a lingual direction; contact is not lost until there is a wide deflection of movement.
• The mesiopalatal cusps of the maxillary molars slide out of the central fossa along the main developmental groove on the triangular ridges of their antagonists in a lingual direction. On the nonworking side in the maxilla, the centric stops slide out of the contact areas (approximal furrows, central fossae) in a lingual direction. The occlusal guidance paths in the maxilla are the buccally directed oblique surfaces of the triangular ridges of the maxillary palatal cusps. The lingual movement paths lose contact in regular in-tercuspal conditions, which is taken into account in permanent restoration work.
• The buccal centric stops of the mandibular premolars and the mesiobuccal cusps of the mandibular molars slide from the approximal marginal ridges of the maxillary antagonists on the cusp ridges to the cusp tips in a lingual direction.
• The distobuccal cusps of the mandibular molars slide out of the central fossae on the mesial triangular ridges of the maxillary mesiopalatal molar cusps in a lingual direction. On the nonworking side in the mandible, the centric stops slide out of the contact areas in a vestibular direction. The occlusal guidance paths in the mandible are the lingually directed oblique surfaces of the buccal cusps.
• The palatal cusps of the maxillary premolars and the distopalatal cusps of the maxillary molars slide from the approximal marginal ridges of the mandibular teeth along the mesial triangular ridges of the mesiobuccal mandibular cusps.
• The mesiobuccal cusps of the maxillary molars slide out of the central fossae on the mesial articulation surfaces of the distobuccal cusps of the mandibular molars.

In complete dentures, the stabilizing balancing contacts lie on the palatal cusps in the maxilla or on the vestibular cusps in the mandible. If guidance by a particular group of teeth (canine or anterior guidance) is being constructed, all the contact areas of the other teeth are raised.