Bite Jaw Research Articles

Jaw Bite Force to Predict Masseter Muscle Thickness and Swallowing Functions

Jaw Bite Force to Predict Masseter Muscle Thickness and Swallowing Functions

Letter to the Editor.

Dear Editor,The oral implantologist's goal is a long term functional and esthetic outcome.1 In planning for this, various data are collected and evaluated. One parameter that has not been seriously considered in the past is the patient's bite force capability (BFC).Treatment planning centers around function, esthetics, and loading. This is accomplished by implant size selection, implant positioning, and prosthetic design. Jaw bite force is generally 2–3 times greater in the posterior jaws than the anterior. Overloading the supporting bone is a basic caveat. Thus, implant size and position are important to prevent an overload of the supporting bone.2–6 Nonetheless, the patient's BFC is the vector behind this occlusal load. It is important, then, for the clinician to have this value to consider implant size, position, and prosthetic occlusal scheme.2–6Patient bite force capability ranges from 50 to 300 N. Thus, a patient with a low BFC may not require a large long diameter implant in the anterior jaw, but a large BFC may require a long large diameter implant to resist a greater load: larger diameter, long implants may be necessary to prevent an overload. The wider the implant, the less per square millimeter load there is on the supporting bone.2–6 However, implants placed in the anterior Class I maxilla will be subjected to a lingual off-axial load from the mandibular anterior teeth. There may not be generous site length in this area for a large implant. A smaller diameter implant may be required. The prudent clinician may measure the BFC as a guide to implant length and width. A prophylactic lingual relief may be needed to ensure mitigation from that load.2–6Implants placed in the posterior jaws can be subjected to extreme functional and parafunctional loads. Thus, larger diameter and longer length implants may be required to resist these loads and BFC may be appropriate for proper planning.2–6 A patient with a low BFC may do well with almost any occlusal scheme, but a greater BFC may require an anterior guided occlusal scheme to protect posterior implants from an off-axial load.2–6A tooth size may present a lever to the opposing dentition. The force on such a lever may impart a magnified load on the supporting bone, thus the clinician should take BFC into account during planning.2–6Of all the diagnostic parameters, the most important datum may be the BFC. This value influences all the other parameters to a minor or major extent. It may be the primary consideration for a long-term function and esthetic outcome.2–6

Development of evaluation methods and determination of hardness variation with leaf order and tissue type of Kimchi cabbage during summer harvest

The texture of Kimchi cabbage was investigated by determining the hardness variation of midribs by leaf order and midrib position and analyzing the hardness characteristic by probe type. The objective of this research was the development of assessment methods for hardness of Kimchi cabbages in cropping types of summer season production. The hardness of the midrib of Kimchi cabbage leaves varied depending on the degree of development of the internal and external epidermis and the vascular tissues. The midrib hardness of Kimchi cabbage leaves did not differ significantly among cultivation types and tended to be lower toward the inner leaf. Using the Volodkevich bite jaws probe or blade set probe to measure the cutting force proved to be a suitable approach for examining the texture characteristic of Kimchi cabbage. The peak force of hardness in volodkevich bite jaw probe test the smallest distance and the second and third peak force intervals distance showed shortest among all the tested probes. In addition, hardness force tests with inside and outside results pattern was similar. When measuring the cutting force of midrib by these probes, it is preferable to measure from the outer epidermis to the inner epidermis of the leaf midrib, at 40–50 mm from the leaf stalk, on the 2nd to 6th outer leaves of Kimchi cabbage head formation.

Effect of sward height on short-term intake by steers grazing winter oat pastures

Sward structure and animal grazing behaviour are key variables in determining herbage intake. The present study was carried out with the objective of evaluating the effect of different sward heights (SH) on the short-term ingestive behaviour variables, in steers grazing winter oats (Avena sativa cv. Calén). Six Holstein-Friesian steers (196 ± 4 kg LW), grouped into three pairs, grazed on swards with different surface heights (SH): 40 cm (SH40), 50 cm (SH50), and 60 cm (SH60). Short-term intake rates (IR) were estimated during grazing sessions of 1 h by the double-weighing technique with correction for insensible weight losses. The number of grazing jaw movements (GJM) and bite jaw movements were measured using the acoustic recorder technique. Measurements were conducted along three consecutive days. On each day, the pairs of steers grazed on one of the SH (1 pair per SH per d). Sound files were analysed visually and aurally. Number of GJM and BJM were determined during three 5-min periods, from minute 5 to 10, from minute 27 to 32 and from minute 50 to 55 of the 1 h grazing session. Bite mass (BM) was calculated as the quotient between IR and the number of bites. Variables of grazing behaviour were analysed by ANOVA according to a 3 × 3 Latin Square design. Classes included in the model were treatment, pair of animals, day, observation time window, and the interaction between treatment and observation time window. Unexpectedly, BM was not affected by the SH (P = 0.97; 0.59, 0.61 and 0.60 g DM bite−1, for SH40, SH50 and SH60, respectively). Similar BM were the result of a numerical, non-significant, decrease in IR (P = 0.65; 30.2, 29.6 and 26.3 g DM min−1, for SH40, SH50 and SH60, respectively), together with a decrease in bite rate (BR; P< 0.001; 51.8, 49.1 and 44.3 bite min−1, for SH40, SH50 and SH60, respectively) with increasing SH. The rate of GJM was similar among treatments (P = 0.50; 88.4, 90.4 and 89.7 GJM min−1, for SH40, SH50 and SH60, respectively). Similar rates of GJM and different BR resulted in increasing numbers of GJM per bite as SH increased (P< 0.001; 1.73, 1.88 and 2.05 GJM per bite, for SH40, SH50 and SH60, respectively) showing than more manipulative grazing jaw movements were needed to form a bite when the steers grazed on the taller swards.

Bite force is limited by the force–length relationship of skeletal muscle in black carp,Mylopharyngodon piceus

Bite force is critical to feeding success, especially in animals that crush strong, brittle foods. Maximum bite force is typically measured as one value per individual, but the force-length relationship of skeletal muscle suggests that each individual should possess a range of gape height-specific, and, therefore, prey size-specific, bite forces. We characterized the influence of prey size on pharyngeal jaw bite force in the snail-eating black carp (Mylopharyngodon piceus, family Cyprinidae), using feeding trials on artificial prey that varied independently in size and strength. We then measured jaw-closing muscle lengths in vivo for each prey size, and then determined the force-length relationship of the same muscle in situ using tetanic stimulations. Maximum bite force was surprisingly high: the largest individual produced nearly 700 N at optimal muscle length. Bite force decreased on large and small prey, which elicited long and short muscle lengths, respectively, demonstrating that the force-length relationship of skeletal muscle results in prey size-specific bite force.

The implications of compound chew–bite jaw movements for bite rate in grazing cattle

Many aspects of the management of grazing systems are directly or indirectly related to the rate of herbage intake achieved by the animal. Intake rate depends, in part, on the time budget of the process, which derives from the basic behavioural component—the jaw movement. Chewing and biting jaw movements have generally been considered mutually exclusive, but acoustic monitoring has demonstrated the existence of the compound chew–bite jaw movement. We used a simple model to examine the implications of chew–bites for the forage-intake time budget, and tested it empirically. The model defines the total number of jaw movements per bite ( α) and the number of chew actions per bite ( β) in relation to the allocation of jaw movements between chews, bites and chew–bites. We examined empirically the variation among animals in the allocation of jaw movements for cattle ( Bos taurus L.) grazing leafy, uniform swards in two separate studies. Grazing sessions were recorded on video, with the sound track originating from a forehead microphone. Each sound burst produced by a jaw movement was classified as a bite, chew or chew–bite. Jaw movements in these segments generated a virtually uninterrupted, regular succession of bite, chew and chew–bite sounds. Among individual animals, the variation in the rate of jaw movement was extremely low (Study 1: mean = 78.9 min −1, CV = 6%; Study 2: mean = 77.9 min −1, CV = 4%), but variation in the allocation of jaw movements was high (CV of proportion of jaw movements allocated to bites, chews and chew–bites = 58, 21 and 50%, respectively, for Study 1; 32, 12 and 32%, respectively, for Study 2). The proportions of chews and bites traded off directly against chew-biting. As the proportion of chew–bites increased, the number of jaw movements per bite declined and therefore the bite rate increased. Different combinations of the three types of jaw movement conformed to an isocline of a constant number of chew actions per bite (CV = 11 and 9% for Studies 1 and 2, respectively). Furthermore, this ratio was close to unity (1.27 and 1.24 chews per bite for Studies 1 and 2, respectively), and was similar for different levels of herbage mass in the range 145–255 g m −2. The possible implications of these findings for the regulation of bite weight and diet quality are discussed.

Observation of bolus position with standardized test foods and fluoroscopic technique

SUMMARY Sugar and agar balls containing barium were made for the fluoroscopic observation of the bolus position during habitual side chewing in 13 adult males (aged from 20 to 28 years) who had a complete dentition and healthy masticatory system. The test foods had constant size, shape, weight and known hardness, i.e. type 1, 20 kg; type 2, 40 kg; type 3, 1.0 kg and type 4, 0.5 kg. These four types of test foods were chewed randomly in a fluoroscopic room. The jaw separation distance and the bolus position during first bite and crushing bite were observed. The influence of the chewing order of four types of test foods on the bolus position was also recorded. It was found that both hard and soft test foods were most often crushed at the first molar area, and the separation distance during the crushing bite was only slightly wider than the diameter of the food. The first bite jaw separation distance for hard food chewing was significantly wider than soft food chewing and the later in the chewing order the wider the separation distance. The effect of chewing order was not significant on the position and jaw separation distance of the crushing bite.

Functional morphology of the pharyngeal jaw apparatus in perciform fishes: An experimental analysis of the haemulidae.

A new mechanical model for function of the pharyngeal jaw apparatus in generalized perciform fishes is developed from work with the family Haemulidae. The model is based on anatomical observations, patterns of muscle activity during feeding (electromyography), and the actions of directly stimulated muscles. The primary working stroke of the pharyngeal apparatus involves simultaneous upper jaw depression and retraction against a stabilized and elevating lower jaw. The working stroke is characterized by overlapping activity in most branchial muscles and is resolved into three phases. Four muscles (obliquus dorsalis 3, levator posterior, levator externus 3/4, and obliquus posterior) that act to depress the upper jaws become active in the first phase. Next, the retractor dorsalis, the only upper jaw retracting muscle, becomes active. Finally, there is activity in several muscles (transversus ventrales, pharyngocleithralis externus, pharyngohyoideus, and protractor pectoralis) that attach to the lower jaws. The combined effect of these muscles is to elevate and stabilize the lower jaws against the depressing and retracting upper jaws. The model identifies a novel mechanism of upper jaw depression, here proposed to be the primary component of the perciform pharyngeal jaw bite. The key to this mechanism is the joint between the epibranchial and toothed pharyngobranchial of arches 3 and 4. Dorsal rotation of epibranchials 3 and 4 about the insertion of the obliquus posterior depresses the lateral border of pharyngobranchials 3 and 4 (upper jaw). The obliquus dorsalis 3 muscle crosses the epibranchial-pharyngo-branchial joint in arches 3 and 4, and several additional muscles effect epibranchial rotation. Five upper jaw muscles cause upper jaw depression upon electrical stimulation: the obliquus dorsalis 3, levator posterior, levator externus 3/4, obliquus posterior, and transversus dorsalis. This result directly contradicts previous interpretations of function for the first three muscles. The presence of strong depression of the upper pharyngeal jaws explains the ability of many generalized perciform fishes to crush hard prey in their pharyngeal apparatus.

A possible relationship between aspects of dentition and feeding in the centrarchid and anabantoid fishes

Certain components of dentition — teeth on the third basibranchial in the Centrarchidae and on the parasphenoid in the anabantoids (sensu lato) — are very rare elsewhere in higher teleostean fishes. Though these basibranchial and parasphenoid teeth in the two fish groups are on opposite sides of the oral cavity, it is hypothesized that they both developed as adaptations for gripping a particular category of food items, namely strong-clawed, hard-shelled, active animals that, once within the oral cavity, would try to crawl out again. A corollary to this hypothesis is that higher teleosts with extensive dentition in the central part of the oral cavity have a grasping jaw bite, which, unlike a piercing, shearing, or crushing jaw bite, does not necessarily kill the prey that is taken into the oral cavity.

Responses of monkey precentral cortical cells during a controlled jaw bite task.

Responses of monkey precentral cortical cells during a controlled jaw bite task.

The regulation of the jaw bite force in man

Experiments were carried out on 12 adult subjects to measure their ability to grade forces between their anterior teeth when using different conditions of perceptual reference. The subjects placed their anterior teeth across a force transducer to produce isometric forces corresponding to a series of integers called by the experimenter in random order every two seconds. The value zero was taken to be zero force and the largest integer as their maximum comfortable bite. The results, which were analyzed by a technique based upon information theory, demonstrated that the mean performance of the subjects as a group was 2.5 bits, S.D. ± 0.3 (approximately 5 discrete levels) when 10 levels were attempted. When reinforcing references were regularly interspersed between the test integers, the mean performance was raised to 2.8 bits, S.D. ± 0.2 (approximately 6 levels). The use of 20 input levels raised the performance of 4 selected subjects to 3 bits (approximately 8 levels). The results suggest that bite force discriminatory ability is much better when an immediately preceding reference is used, than when an overall conceptual reference is employed.