Chewing kinematics are well-documented in several mammal species with fused mandibular symphyses, but relatively understudied in mammals with an unfused symphysis, despite the fact that more than half of extant Mammalia have an unfused mandibular symphysis. The Wistar brown rat (Rattus norvegicus) is widely used in human health research, including studies of mastication or neurological studies where mastication is the output behavior. These animals are known to have unfused mandibular symphyses and proal jaw (rostrocaudal) motion during occlusion, but the lack of high resolution, 3-dimensional analysis of rat chewing leaves the functional significance of symphyseal mobility unknown. We used biplanar fluoroscopy and the X-ray reconstruction of moving morphology workflow to quantify chewing kinematics in 3 brown rats, quantifying overall jaw kinematics, including motions about the temporomandibular joint and unfused mandibular symphysis. During occlusion, the teeth and the mandibular condyle translate almost exclusively anteriorly (proal) during occlusion, with little motion in any other degrees of freedom. At the symphysis, we observed minimal flexion throughout the chew cycle. Overall, there are fundamental differences in jaw kinematics between rats and other mammals and therefore rats are not an appropriate proxy for ancestral mammal jaw mechanics. Additionally, differences between humans and rat chewing kinematics must be considered when using rats as a clinical model for pathological feeding research.
McParland, E. D., et al. "The Kinematics of Proal Chewing in Rats." Integrative Organismal Biology, vol. 6, no. 1, Jul. 2024. https://doi.org/10.1093/iob/obae023
McParland, E. D., Mitchell, J. K., Laurence-Chasen, J. D., Aspinwall, L. C., Afolabi, O., Takahashi, K., Ross, C. F., & Gidmark, N. J. (2024). The Kinematics of Proal Chewing in Rats. Integrative Organismal Biology, 6(1). https://doi.org/10.1093/iob/obae023
McParland, E. D., Mitchell, J. K., Laurence-Chasen, J. D., et al., "The Kinematics of Proal Chewing in Rats," Integrative Organismal Biology 6, no. 1 (2024), https://doi.org/10.1093/iob/obae023
@article{osti_2471201,
author = {McParland, E. D. and Mitchell, J. K. and Laurence-Chasen, J. D. and Aspinwall, L. C. and Afolabi, O. and Takahashi, K. and Ross, C. F. and Gidmark, N. J.},
title = {The Kinematics of Proal Chewing in Rats},
annote = {Chewing kinematics are well-documented in several mammal species with fused mandibular symphyses, but relatively understudied in mammals with an unfused symphysis, despite the fact that more than half of extant Mammalia have an unfused mandibular symphysis. The Wistar brown rat (Rattus norvegicus) is widely used in human health research, including studies of mastication or neurological studies where mastication is the output behavior. These animals are known to have unfused mandibular symphyses and proal jaw (rostrocaudal) motion during occlusion, but the lack of high resolution, 3-dimensional analysis of rat chewing leaves the functional significance of symphyseal mobility unknown. We used biplanar fluoroscopy and the X-ray reconstruction of moving morphology workflow to quantify chewing kinematics in 3 brown rats, quantifying overall jaw kinematics, including motions about the temporomandibular joint and unfused mandibular symphysis. During occlusion, the teeth and the mandibular condyle translate almost exclusively anteriorly (proal) during occlusion, with little motion in any other degrees of freedom. At the symphysis, we observed minimal flexion throughout the chew cycle. Overall, there are fundamental differences in jaw kinematics between rats and other mammals and therefore rats are not an appropriate proxy for ancestral mammal jaw mechanics. Additionally, differences between humans and rat chewing kinematics must be considered when using rats as a clinical model for pathological feeding research.},
doi = {10.1093/iob/obae023},
url = {https://www.osti.gov/biblio/2471201},
journal = {Integrative Organismal Biology},
issn = {ISSN 2517-4843},
number = {1},
volume = {6},
place = {United States},
publisher = {Oxford University Press},
year = {2024},
month = {07}}