Florian J. Knap

Study of Mandibular Motion in Six Degrees of Freedom

A great deal of effort has been expended in the past 50 years to gain basic information on jaw motion, condylar action, neuromuscular activity, and occlusion. The methods used in gaining this information include photography, radiography, pantography. cinefluorography, and electromyography. McCollum and Stuart,1 using the pantographic method, have formulated many of the concepts used in dentistry today. Recent work with an electronic apparatus by Beck and Morrison,2 and later by Messerman,3 has revealed some of the advantages of these methods. The objective of this study was to obtain simultaneous, three-dimensional data on mandibular motion.

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.

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.

Evaluating occlusal relationships, mandibular dysfunction, and temporomandibular joint pain by palpation

Abstract The strength and sequence of contraction of the muscles that elevate the mandible and the location of tender regions in the muscles involved in maxillomandibular movements provided significant clinical information regarding occlusal relations. The 12 step examination sequence is easy to perform and valuable to diagnosis of oral relations and evaluation of treatment procedures (Table I).

Reliability of fully adjustable articulators using a computerized analysis

1. Statistical analysis of the graphic data showed no significant difference between the Denar D5A and Hanau 130-21 articulators for the five subjects tested. 2. The average horizontal Gothic arch angle (beta) at incision was 135 degrees. 3. The functional stroke for the subjects was approximately 5 mm. in the incisor region and 2.5 to 3 mm. in each molar region. 4. Both the Denar D5A and Hanau 130-21 articulators adequately reproduced jaw motion for the five subjects tested.

Analysis of occlusion before and after occlusal adjustment

Abstract This study investigated the movement between the initial occlusal contact when the mandible was in centric relation and the intercuspal position on the sagittal plane before and upon completion of occlusal adjustment in ten patients. Digital data were compiled to ascertain the stability of the adjusted dentition two months after the final adjustments were complete. Important findings included the following: 1. Mandibular jaw motion from occlusal contact in centric relation to the intercuspal position was greater in the vertical plane than in the horizontal plane when measured in front of the anterior teeth. The ratio was 2.3 to 1 (vertical to horizontal). 2. Mandibular motion from retruded contact to the intercuspal position when analyzed at the point of first interceptive contact occurred at a ratio of 1.4 to 1 (vertical to horizontal). 3. The mean digital relapse of the adjusted occlusion was 0.29 mm. in the vertical component and 0.22 mm. in the horizontal component. 4. The mean relapse of the adjusted occlusion was 28.9 per cent in the vertical component and 30.1 per cent in the horizontal component. However, both represent relatively small digital values. 5. Clinically, the percentage relapse is not indicative of the therapeutic value of the occlusal adjustment.

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.

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.

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.