A study of anterior guidance.

PURPOSE: This study focuses on the curvature and inclination of the lingual surfaces of the maxillary anterior teeth from the transition point on the cingulum to the incisal edge. MATERIALS AND METHODS: On 32 sets of mounted casts, 768 measurements were made of the curvature of the lingual surfaces utilizing radius gauges. The inclination of the lingual surface relative to the occlusal plane was recorded. The relationship of the incisal edge of the mandibular teeth to the transition point on the cingulum of the maxillary teeth was determined. Centric occlusion contact was noted on each tooth. RESULTS: Significant differences were found between the measured areas of any one tooth and between the types of teeth. The average radius ranged from 20.5 mm on the mesial ridge of the canine to 5.3 mm in the fossa of the central. The average inclination of the lingual surfaces was 46 degrees. In centric occlusion, 97% of the canines and 59% of the centrals and laterals were in contact with the opposing teeth. These contacts occurred 2.8 mm incisal to the transition point. The centrals contracted two opposing teeth (45%), and canines contacted one opposing tooth (53%). CONCLUSIONS: The function and curvature of the incisor teeth vary considerably from those of the canines. Overcontouring the lingual surfaces of the maxillary incisors to gain contact is not normal and may be detrimental.

Analysis of jaw movements in patients with temporomandibular joint click.

Although TMJ click is common, its relationship to subjective and objective evaluation and the position of the click within the envelope of motion is not fully understood. This study attempted to correlate these entities in 21 patients. Although specific conclusions are difficult to make from this study, the findings suggest the following: The most important etiologic factors in the click are bruxism, clenching, an occlusal slide from centric relation to centric occlusion of more than 1 mm, and lateral deviation. The most important clinical sign of TMJ clicking is palpable soreness in the lateral pterygoid and temporal muscles. Over 50% of patients with a click have bilateral click. A click occurs least often in retruded closing movement (7%) and most often in habitual movement (37%). Although it appears that closure in the retruded position may avoid click, further evaluation of the presence of click in retruded opening movement is indicated. A mean mandibular lateral deviation of 2.2 mm anteriorly is observed at the time of click.

Fabrication of a crown and fixed partial denture remount cast.

A technique has been described for fabricating an accurate working cast in which the finished crowns are easily removable.

Border molding in mandibular denture impressions.

A modification of the border molding technique for lower dentures has been presented to increase the accuracy of this procedure.

Procedural problems in using the Denar pantograph as a transfer-bow.

A method has been described for using zinc-oxide/eugenol paste as an interclutch support when the Denar pantograph is used as a transfer-bow. Using this technique a stable centric relation position can be maintained during the maxillary cast mounting procedure and the subsequent setting of the articulator to the pantographic recordings.

Computerized analysis and duplication of mandibular motion.

A new digital system has been devised to analyze and duplicate jaw motion. The arrangement of the electronic system offers a range of versatility which includes graphic as well as numerical data analysis. The duplicator linkage is identical to the sensor linkage which, together with an accurate model transfer system, results in an encouraging level of accuracy in jaw-motion duplication. The data collected from normal subjects should offer some new knowledge in the normal motions of the mandible as well as establish a reference for comparison with abnormal masticatory function.