Mandibular movement and muscle activity during mastication in the guinea pig (Cavia porcellus)

Abstract

Optoelectronic analysis of mandibular movement and electromyography (EMG) of masticatory muscles in Cavia porcellus indicate bilateral, unilateral, and gnawing cycles. During bilateral and unilateral cycles, the mandibular tip moves forward, lateral, and down during the lingual phase of the power stroke to bring the teeth into occlusion. EMG activity is generally asymmetric, with the exception of activity of the temporalis muscle during bilateral cycles. During gnawing cycles, the mandible moves in an anteroposterior direction that is opposite that during bilateral and unilateral chew cycles. Bilateral and unilateral cycles of pellets were significantly longer than carrot. With the exception of the width of bilateral cycles, the magnitude of cycle width, length, and height during the mastication of carrots was greater than that during the mastication of pellets. Significant differences exist between EMG durations during mastication of pellets and carrots. The lateral pterygoid displays continuous activity during gnawing cycles. Significant differences also exist in the duration of EMG activity between the working and balancing side during all three cycle types. High level of activity of balancing side temporalis and anterior belly of digastric (ABD) during bilateral cycles occurs during rotation and depression of the mandible during the power stroke. The temporalis apparently provides a "braking" or compensatory role during closing and power strokes. Differences between Cavia masticatory patterns and those shown by Rattus and Mesocricetus are apparently due to differences in dental morphology, occlusal relationships, and, possibly, the poorly developed temporalis in Cavia. The large number and wide diversity of rodent groups afford students of mammalian mastication an opportunity to investigate and compare different masticatory specializations.

Response of the Mandibular Joint to Loss of Incisal Function in the Rat

“…Since the molar and incisor teeth cannot be occluded simultaneously in a rodent, the lower jaw must be protruded considerably front the position of molar-to-molar contact in order to grasp an object between the incisors. Studies of rodent feeding behavior [8][9][10][11] have demonstrated that incisal preparation of food is an integral part of the masticatory cycle. During incisal biting, the lower jaw is depressed and protruded prior to elevation and food contact.…”

Biplanar X-ray motion analysis of the lower jaw movement during incisor interaction and mastication in the beaver (Castor fiber L. 1758)

“…Also for cats phases of mandibular cycle are at least partially determined by the consistency of food (Thexton et al 1980) and the same was seen in Tupaia (Scandentia, Fish and Mendel 1982). Similarly for the rodent Cavia porcellus cycle lengths varied with food type from about 319 ± 33 to 310 ± 32 ms in bilateral and 174 ± 16 to 153 ± 15 ms in unilateral cycles (Byrd 1981). For the beaver the actual lateroanterior power stroke was about 140 ms; the sequence from maximal gape position to cheek teeth interaction and reaching maximal gape position again is about 360 ms.…”

“…Hiiemäe 1967;Weijs andDantuma 1975, 1981;Crompton and Hiiemäe 1970;Byrd 1981;Hiiemäe and Crompton 1971;Hiiemäe and Ardran 1968;Hiiemäe and Kay 1973;Luschei and Goodwin 1974;Gans and de Vree 1974;Oron and Crompton 1985), reviewed by Hiiemäe (1978). She distinguished "three components or strokes in a single cycle: a closing stroke (fast close) in which the teeth are converging and the lower jaw is moving rapidly upwards; a power stroke in which work, i.e.…”

Mammalian Oral Rhythms and Motor Control

“…Orthodontic brackets or custom clutches with small footprints are often attached to teeth for holding jaw tracking markers (Flavel et al, 2002;Gerstner & Fehrman, 1999;Gerstner & Kinra, 1999;Gerstner & Parekh, 1997;Hiiemae et al, 1996;Plesh et al, 1993;Wintergerst et al, 2004). More invasive tracking methods such as anchored bone markers or cineradiography are easily used in non-human mammals (Byrd, 1981;Gerstner & Goldberg, 1991;Hylander et al, 1987;Kobayashi et al, 2002a;Schwartz et al, 1989;Yamada et al, 1988). The development of X-ray reconstruction of moving morphology (XROMM) has been used to study oral movements and promises to revolutionize comparative biomechanical studies of oral function (Brainerd et al, 2010).…”