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In vivo bone strain in the mandible of Galago crassicaudatus
Author(s) -
Hylander William L.
Publication year - 1977
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/ajpa.1330460212
Subject(s) - galago , strain gauge , bite force quotient , biting , anatomy , mandible (arthropod mouthpart) , strain (injury) , lever , isometric exercise , tension (geology) , wheatstone bridge , materials science , compression (physics) , biomedical engineering , biology , orthodontics , medicine , composite material , primate , botany , physiology , ecology , physics , quantum mechanics , neuroscience , voltage , resistor , genus
Single element foil strain gages were bonded to mandibular cortical bone in eight specimens of Galago crassicaudatus . The gage was bonded below the Pm 4 or M 2 adjacent to the lower border of the mandible. The bonded strain gage was connected to form one arm of a Wheatstone bridge. Following recovery from the general anesthetic, the restrained Galago bit either a piece of wood, a food object, or a bite force transducer. During these biting episodes, mandibular bone strain deformed the strain gage and the resulting change in electrical resistance of the gage caused voltage changes across the Wheatstone bridge. These changes, directly proportional to the amount of bone strain along the gage site, were recorded by a strip chart recorder. Bone strain was measured on both the working and balancing sides of the jaws. Maximum values of bone strain and bite force were 435 microstrain (compression) and 8.2 kilograms respectively. During bending of the mandible, the correlation between bone strain (tension or compression) and bite force ranged from ‐0.893 (tension) to 0.997 (compression). The experiments reported here demonstrate that only a small percentage of the Galago bite force is due to balancing side muscle force during isometric unilateral molar biting. In addition, these experiments demonstrate that the Galago mandible is bent in a predictable manner during biting. The amount of apparent mandibular bone strain is dependent on (1) the magnitude of the bite force and (2) the position of the bite point.