Abstract
AimsTooth-contact sensations are considered essential to boost jaw adductor muscles during mastication. However, no previous studies have explained the importance of the inhibitory reflex of human anterior-tooth (ANT)-contacts in mastication. Here I present the “reciprocal reflex-control-hypothesis” of mammalian mastication.Subjects and setting of the studyI demonstrate the hypothesis with the live kinematics of free jaw-closures as inferred from T-Scan recordings of dental patients.ResultsThe jaw-closures started with negligible force, predominantly with ANT-contacts (the AF-bites). The first ANT-contact inhibited the first kinematic tilt of the mandible, whereas the bites starting from a back-tooth (BAT)-contact (the BF-bites) accelerated the first tilt. The second tilt established a low-force static tripod of the ANT- and bilateral BAT-contacts for a fixed mandible-maxilla relation. Thereafter, semi-static bite force increased rapidly, relatively more in the BAT-area.Discussion and ConclusionsIn the vertical-closure phase of chewing, the primate joint-fulcrum (class 3 lever) conflicts with the food-bolus-fulcrum in the BAT-area (class 1 lever). The resilient class 3 and 1 lever systems are superseded by an almost static mechanically more advantageous class 2 lever with a more rigid fulcrum at the most anterior ANT-contact. For humans, the class 2 levered delivery of force also enables forceful horizontal food grinding to be extended widely to the BAT-area.
Highlights
From studies comparing the chewing capacity of natural, and implant-supported dentitions, it has been concluded that the periodontal mechanoreceptor (PMR) -elicited added muscle activity is essential to enhance human masticatory performance.[1]
In the present study I make the assumption of reciprocity of the be crushed almost entirely by the original class 3 lever with the immediate reflex actions between the ANT- or BAT-contacts of temporomandibular joint (TMJ)-area as its fulcrum (Fig. 1, left mastication to explain the selective activation of the antagonistic panel)
The “ANT is not BAT” -dichotomy of PMR sensory inputs According to the main hypothesis of this study, the “reciprocal reflex-control-hypothesis”, a sensory signal is required from BATcontacts for the temporal and masseter muscles to activate, whereas ANT-contacts cause an immediate inhibition of the same muscles
Summary
From studies comparing the chewing capacity of natural, and implant-supported dentitions, it has been concluded that the periodontal mechanoreceptor (PMR) -elicited added muscle activity is essential to enhance human masticatory performance.[1]. In this study the teeth of the human dental arches were first contacts in both ANT-, and BAT -areas (the SIM-bites) during the first 10 ms of the recorded bite.[22] dichotomised to belong either to the “immediately inhibitory ANT”. In the present study I make the assumption of reciprocity of the be crushed almost entirely by the original class 3 lever with the immediate reflex actions between the ANT- or BAT-contacts of temporomandibular joint (TMJ)-area as its fulcrum (Fig. 1, left mastication to explain the selective activation of the antagonistic panel). 1. The timepoints and the force parameters of this study tZ – the time-point of the first, uninterrupted, anterior area tooth contact of each bite, leading to a complete occlusion in all parts of dentition.
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