Zum initialen Einfluss weiter Mundöffnungen bei zahnärztlicher Behandlung auf das Bewegungsmuster der Mandibula

The following clinical experimental study addresses a possible influence of long-lasting wide opening of the mouth, as usual during dental treatment, to the individual moving pattern of the lower jaw. Fifteen male test persons with healthy dental conditions and chewing functions, aged between 19 and 26, participated in this test series. A total of two measuring cycles have been evaluated for every proband. The first measuring cycle has been carried out in a relaxed condition directly before the approx. 30 minutes lasting wide mouth opening. The second measuring cycle has been recorded straight after the mouth opening phase. The following movements have been documented with the computer aided JMA-Registration System of the Zebris company: Closing motion from wide mouth opening, dental leaded excursive protrusion and laterotrusion to the right and left. Possible variations of movements have been specified in horizontal and sagittal plane with the angles α (for adduction), β (left-laterotrusion), γ (right-laterotrusion) and δ (protrusion). The comparison of both measuring cycles resulted under long-lasting mouth opening in a significant reduction of: 1. the closing angle α by 2,1°, 2. the laterotrusion angle β by 1,7° and γ by 2.1° as well as 3. the protrusion angle δ by 1,6°. The changed moving traces result inevitably in an at least temporary alteration of the occlusal compasses. The results of occlusal controls, which are carried out directly after a long-lasting dental treatment, should be therefore interpreted with reservation. Apparent occlusal interferences could be the implication of a changed moving pattern of the mandible through mouth opening. This circumstance should be considered also for the selective occlusal grinding-in as well as the centric jaw relation determination and the protrusive and laterotrusiven check-bite for the programming of the articulator.