The effect of anteroposterior inclination of the occlusal plane on biting force.

With the experimental design of this study the following conclusions were reached. 1. Biting force during maximum clenching was the greatest when the occlusal plane was made parallel to the ala-tragus line. It decreased when the occlusal plane was inclined about 5 degrees anteriorly or about 5 degrees posteriorly. 2. The efficiency of biting force exertion during maximum clenching showed the best value when the occlusal plane was made parallel to the ala-tragus line. 3. Muscle activity during clenching at various given forces was least when the occlusal plane was made parallel to the ala-tragus line. The anteroposterior inclination of the occlusal plane tends to affect the biting force, and the method with the ala-tragus line seems to be the most reasonable for occlusal plane orientation.

Ventilatory responses to CO2 rebreathing at rest and during exercise in untrained subjects and athletes.

Ventilatory responses to CO2 during rest and exercise were studied in 10 marathon runners and 14 untrained subjects by the rebreathing method. The average responses of the untrained subjects and athletes at rest as meausred by the slope of VE-PACO2 curves were 1.86 and 1.12 liters/min-mmHg, the difference being statistically significant (p less than 0.05). During exercise the slope of VE-PACO2 decreased from 1.86 to 0.62 in the controls, and from 1.12 to 0.62 in the athletes (p less than 0.01). The mean slope obtained in the athletes, at rest and during exercise, was about 50-60% of that in untrained subjects (p less than 0.05). The difference in the VE-PACO2 curves between the athlete and the untrained group may be due to a reduced exitability of the respiratory center and/or by a reduced input signal.