[Interocclusal clearance and changes in occlusal position in dentate and edentulous jaws. 1]. / Interokklusalabstand und Bisslageänderung beim Bezahnten und Zahnlosen. Teil 1: Zur Reproduzierbarkeit der Ruheschwebelage.

Six methods of assessing the resting position were evaluated in this study of 22 patients with teeth and 10 edentulous patients. None of these methods yielded reproducible results. The resting position is not a fixed, constant value, but depends on the method used. As could be shown by means of the standard deviation the method used to determine the resting position has a considerable influence on the distribution, and hence on the margin of error when the vertical relation is being determined. Small ranges of distribution were achieved: a) by means of the closest speaking distance when the patient spoke the numbers from 60 to 70 in a natural voice, b) after prompt relaxation of the lower jaw when the patients were asked to relax their jaws, c) when the interocclusal distance was measured after the mouth had been opened a little and the lips subsequently touched again lightly. Since there is little difference in the values with any one patient the three methods can be recommended for practical use.

[Cuspid protection and muscular reaction]. / Eckzahnführung und muskuläre Reaktion.

In an epidemiological study we found bilateral cuspid guidance in only 4, and unilateral cuspid guidance in 3 patients out of 247 patients examined. This suggest that cuspid guidance is a rare form of articulation. In the experimental part of this study the electric activity of the masseter and anterior temporal muscles was measured during empty mastication before and after the canines were treated with build-ups in a patient group with muscular and TMJ problems and matched against the results obtained in a control group of 10 healthy probands. Apart from the mean muscle activity also the path of excursion was recorded. Both values were combined in activity/path diagrams providing information on the muscular response to different forms of occlusion. Existing balancing contacts in mediotrusion, for instance, may produce high activities. With cuspid build-ups allowing correct cuspid guidance the patients with muscular and TMJ problems were symptom-free after just three days. After approx. one year the patients and the probands were recalled for a follow-up check. These and other results are discussed.

[Studies on the perception of periodontal stimuli]. / Untersuchungen zur Wahrnehmung parodontaler Reize.

The stimulation of the periodontium causes a reflex response of the jaw muscles and at the same time a perceptive reaction of the central nervous system. The aim of our study was to develop a method for the objective assessment of the subjective perception experienced after stimulating the periodontium. Seven healthy volunteers took part in these experiments in the course of which mechanical stimuli (2.5 N, 750 microseconds) were applied perpendicular to the tooth, thus leading to a stimulation of the periodontium. Sensory evoked potentials of the periodontium (SEP-PA) elicited from the EEG served as an objective measure of perception. A computerized analysis of the data thus obtained allows an assessment of the change in perception following repeated periodontal stimulation at different rates.

[Masticatory forces and maximum jaw closure forces of complete denture wearers before and after bite opening]. / Kaukräfte und maximale Kieferschliesskräfte von Totalprothesenträgern vor und nach Bisshebung.

The maximum jaw closure forces and the masticatory forces during the comminution of soft and though food were measured with changing vertical dimensions. The maximum jaw closure force was reduced by a mean 25% in all patients after the vertical dimension had been increased. Significant reductions in the masticatory forces were found only on the working side with the forces decreasing rather during the chewing of soft than tough food. Thus, in chewing sour drops the average masticatory force was 32.9 N as against 46.6 N, whereas in chewing bread it dropped to 21.3 N as against 42.8 N. The study showed that increasing the vertical dimension in endentulous patients up to an interocclusal clearance of 0 mm resulted in a functional impairment of speech and mastication and, above all, in sore spots and inflammations of the mucosa.

[Electronic measurements of the masticatory muscles. 1: Methods of recording]. / Zu elektronischen Messungen an der Kaumuskulatur. Teil 1: Methodik der Ableitung.

The application of surface electromyography as an aid in diagnosing craniomandibular dysfunction requires that pathological or treatment-induced changes of the EMG be distinguished with sufficient probability from random variations due to methodological or biological reasons. It was the aim of this study to determine the range of variability of elevator muscle EMG, to find experimental methods for improving reproducibility, and to establish evaluation procedures that allow the recognition of treatment-induced effects in the EMG even in the presence of great random variations. For this we measured the voltage/tension relation of the elevator muscles of 42 persons in the range of 20 to 500 N on up to 20 different days under constant experimental conditions. The majority of measurements revealed a non-linear correlation between EMG activity and resulting force, hence second order polynomials proved to be more appropriate than straight lines for representing the activity/tension correlation. Muscle activity was found to vary randomly from day to day within each individual. These fluctuations appeared as varying axis intersections, initial slopes and curvatures which are the determinants of the voltage/tension curves. In ten selected subjects random fluctuations were significantly higher when electrodes were repositioned by palpation of the muscle belly than with the aid of tattoos.

[The influence of brushing methods on wedge-shaped defects]. / Einflüsse der Zahnputztechnik auf die Entstehung keilförmiger Defekte.

By experimentally brushing 20 teeth vertically to the tooth axis under a pressure of 2 N only lesions in cementum or dentine could be obtained. There was no case in which enamel was damaged by our brushing experiments. Therefore, defects appearing clinically cannot be explained by wrong tooth brushing techniques. There were several parallel lesions (similar to a saw blade) to be found as well as confluent hard tissue losses. Both indicate the direction of the movement of the tooth brush. The smallest defect to be measured in coronal-apical direction was 2.25 mm, the biggest 6.7 mm. The depth of the defects ranged front 239.9 microns to 493.2 microns. A correlation between Vicker's hardness and substance abrasion could not be proved, nor was the clinical appearance of wedge-shaped defects to be achieved by means of our experimental device. The formation of enamel defects cannot be explained by mere mechanical abrasion due to tooth brushing. In our opinions the formation of wedge-shaped defects implies a multicausal process.