Observations on the use of the Denar pantograph and articulator.

An investigation was undertaken to determine the reproducibility of articular settings from graphic records of simulated mandibular movement using the Denar pantograph and the Denar D4-A articulator. The results of the study showed that most of the articulator adjustments were reproducible with a reasonable degree of accuracy, although not quite to the extent one would hope for. The rear-wall and top-wall adjustments are of questionable value in reproducing mandibular movements with this technique, since the results for these adjustments in the present study were unreliable. However, familiarity with the technique gave better results, as shown in the third experiment. It would, therefore, seem that much of the basis for adverse reports depended upon results obtained by operators with insufficient experience in the technique.     

Potential errors when using a computerized pantograph

This study determined the effect on articulator settings of using an arbitrary hinge axis as compared with the terminal hinge axis in orienting a computerized pantograph on a patient. The effect of an error in measuring the reference plane angle or clutch angle was also determined. Two subjects were pantographed 30 times by using the terminal hinge axis and 30 times by using the arbitrary hinge axis. Statistically the articulator settings obtained by using the arbitrary hinge axis and the terminal hinge axis were different, but the difference was small. One subject was pantographed on 18 occasions by using different reference plane angle and clutch angle settings. Analysis showed that 1-degree change in the reference plane angle setting produced approximately 0.9-degree change in the protrusive and orbiting path articulator settings. A 1-degree change in the clutch angle setting produced approximately 0.9-degree change in the progressive side shift settings. It was concluded that the terminal hinge axis should be used as the posterior reference point and the reference plane angle and clutch angle should be carefully recorded.     

The Denar system and its application in everyday dentistry.

The Denar System is far more than just a pantograph and a fully adjustable articulator. These are just a small portion of the system. Today and system includes instruments for occlusal treatment, educational programs, protocol for dentist-laboratory relations, and laboratory support. Prior to the Denar System, effective occlusal treatment was available only to a select few and it was rendered with the expenditure of considerable time and expense by those few dentists who, after many years of concentrated effort, developed the required skills and eventually overcome the obstacles to providing this service. Today, the Denar System provides the profession not only with the tools but also with the means to acquire, in a few short months, basic occlusal treatment and management skills that took predecessors many years of concentrated effort to develop. Because of the continuing efforts of many of our colleagues in dental education there is currently an increasing level of awareness of the role of occlusion in modern dental practice. These significant educational activities can now be supported by commercial organizations, such as the Denar Corporation, who possess the resources needed to develop whatever instruments or services are required to enable more dentists to implement principles of occlusion in their treatments on a routine basis and to enable them to do so within the economic framework of a modern dental practice.     

Comparison of the intercondylar distance and the interfacial width as used with the electronic pantograph.

The electronic pantograph (Pantronic) records mandibular movements and computes the articulator settings. The Pantronic pantograph does not determine the intercondylar distance but approximates it from the interfacial width at the condyles. An average distance of 12.5 mm is subtracted from each side to determine the intercondylar distance. This study recorded 45 patients' articulator intercondylar distances that had been set from a mechanical pantograph and they were compared with the Pantronic's approximation. The difference between the interfacial width and the actual intercondylar distance was 15.1 mm on the right side and 14.9 mm on the left side. A numerical value of 15.0 mm was statistically superior to the Pantronic's 12.5 mm in estimating the average distance between the intercondylar distance and the surface of the skin at the condyle. No statistically significant difference was found between the differences of interfacial width and intercondylar distance values for men and women (p greater than 0.05). The mean intercondylar distance was 56.5 mm on the right side and 56.7 mm on the left side. A statistically significant difference was found between the mean intercondylar distances of men and women (p less than 0.05).     

Influence of TMJ dysfunction on Bennett movement as recorded by a modified pantograph. Part I: Literature review

This review has pointed out the difficulties in studying the lateral side shift of the mandible (Bennett movement) as well as the many contradictory results that have evolved from investigations.Based on the studies reported, it seems reasonable to conclude that Bennett movement accompanies most subject's lateral jaw movements,^{2, 8, 21, 33, 36, 45} but its amount and “timing” varies between individuals^{33, 45, 46, 52} and may be influenced by muscle incoordination and TMJ dysfunction.^24–27 Furthermore, the axis around which all lateral movements occur may be oblique rather than vertical and perpendicular to the subject's hinge axis.^{43, 49}The importance of Bennett movement has often been emphasized. Disagreement and controversy still exist regarding (1) the immutability of its magnitude throughout occlusal therapy^24–27 and (2) the possible relationship between TMJ dysfunction and Bennett movement.^{24, 25, 27}A clinical study has been completed and will be reported in subsequent articles to give insight into the possible influence of the neuromusculature on the lateral side shift of the mandible.     

Errors incurred in programming a fully adjustable articulator with a pantograph

The ability of experienced and inexperienced dentists to follow graphic tracings of known value was compared. The mean differences from known values were low for the settings of condylar inclination, progressive side shift, and immediate side shift. Errors were high in both groups when the parameters of the top wall and rear wall were evaluated. Further work is necessary to determine the clinical significance of these errors.     

Influence of TMJ dysfunction on Bennett movement as recorded by a modified pantograph. Part III: Progress report on the clinical study

The purpose of this investigation was to provide further insight into the characteristics of the induced and voluntary Bennett movement by determining the influence of TMJ dysfunction on the lateral side shift of the mandible as recorded by a modified pantograph.Twelve subjects were examined using pantographic tracings quantitated with the PRI to establish a baseline pattern of dysfunction for each subject.The PRI was used to categorize the subjects as to the degree of dysfunction. Following categorization, eight subjects were used as an experimental group and four subjects as a control group. On all subjects, induced and voluntary Bennett movement registrations were taken at the initial and final adjustment. Only the experimental subjects underwent an occlusal therapy consisting of an occlusal splint and an occlusal adjustment. Success of the therapy was monitored via the PRI. Following occlusal therapy, the reduction in PRI scores and categorization for the experimental group was significant to the 0.0042 level. There was no significant change in the scores for the control group.Post-treatment Bennett movement registrations (voluntary and induced) indicated a statistically significant increase of the movement at the 0.043 level. The control group showed no significant change. Furthermore, on all subjects studied in this investigation, the voluntary Bennett movement was always within the borders of the induced Bennett movement, suggesting that the subject's neuromus-culature was an important component in registering the lateral side shift of the mandible.     

Condylar determinants in a patient population:electronic pantograph assessment

summary Posterior condylar determinants play a key role in the establishment of a stable and harmonious occlusal scheme. Various methods exist to record the posterior condylar factors. The Denar electronic pantograph® computes these condylar determinants automatically after the execution of a pantographic tracing. Research has validated the accuracy and reliability of this electronic pantograph. Electronic pantographic analysis was carried out on 55 patients referred for various prosthodontic consultations. Values for condylar determinants were recorded and statistically appraised. Values for these condylar determinants were variable with a large range. The variability in condylar values suggests the importance of determining an individual's condylar determinants rather than relying on average values.     

Differences in the transport systems between cementocytes and osteocytes in rats using microperoxidase as a tracer.

Microperoxidase (MP) tracer was injected intravenously into rats to investigate any differences in transport pathways of tissue fluids in the lacunae and canaliculi of cementum and bone. Light microscopically, in deep cementum lacunae, pericellular spaces contained a large amount of MP, while close to the cementum surface, the spaces contained scarcely any. In bone, MP was detected throughout all pericellular spaces. MP was detected intracellularly as granular reaction products in most cementocytes and osteocytes. Electron microscopically, MP was found in the pericellular spaces of cementum and bone lacunae, particularly on collagen fibrils and amorphous material. MP deposits were also intense along the plasma membrane of cementocytes in the deep cementum and along the innermost edge of the deep cementum matrix and bone matrix. In uptake of MP by cementocytes, although extracellular tracer was deposited extensively along the plasma membrane of the deeply positioned cementocytes, uptake by these deep cementocytes was less than that of those close to the surface. However, in bone, most osteocytes showed uniform uptake. These results suggest that the transport pathways for tissue fluids in cementum are in the pericellular spaces, but that cementum has an uneven circulation of tissue fluid. In cementum, although there seems to be a well-developed canalicular system to transport tissue fluid into the deep regions, the deep cementocytes had less endocytotic ability than those close to the surface.     

Procedural due process in the dismissal of residents

Legal commentators and court decisions have defined, generally, procedural due process for students and faculty in institutions of higher learning. Dental residents (GPRs, oral surgery residents, etc.) occupy a unique niche in this educational structure. On the one hand they are students pursuing advanced training; on the other, they are employees and instructors in a hospital or similar institution. As advanced student-clinicians, residents have significant autonomy in patient care. Those who are charged with monitoring a resident's care can be held liable for the resident's negligence. Hospital administrators and residency program directors have concerns about minimizing the chances of malpractice liability, while simultaneously having to observe procedural due process guarantees when a resident's performance mandates dismissal or suspension. This article will briefly review procedural due process issues concerning dismissal or suspension of students and faculty. Court decisions involving dismissal of medical and dental residents will be analyzed to see if the courts follow the student model or faculty model. The cases will demonstrate that the courts generally follow the faculty due process model when residents are suspended or dismissed. Key administrative law decisions will briefly be reviewed that point out the differences of opinion existing over the student/employee status of residents. Also, it will be shown that when patient safety is at stake, procedural due process guarantees can be modified to allow immediate suspension or dismissal of the resident.