Masticatory force or force of mastication is the

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a p ...

created by the dynamic action of the masticatory muscles during the act of chewing.

Masticatory muscles

The muscles that power the jaw movements during chewing are known as the muscles of mastication or masticatory muscles, and are functionally classified as: * Jaw elevators: the

masseter In human anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it ...

temporalis In anatomy, the temporalis muscle, also known as the temporal muscle, is one of the muscles of mastication (chewing). It is a broad, fan-shaped convergent muscle on each side of the head that fills the temporal fossa, superior to the zygomatic a ...

, medial pterygoid and superior belly of the lateral pterygoid * Jaw depressors; the anterior digastrics,

geniohyoid The geniohyoid muscle is a narrow muscle situated superior to the medial border of the mylohyoid muscle. It is named for its passage from the chin ("genio-" is a standard prefix for "chin") to the hyoid bone. Structure It arises from the infe ...

, mylohyoid and inferior belly of the lateral pterygoid

Measuring masticatory force

The first device for measuring masticatory force ( gnathodynamometer) was created by Black in 1893. He determined that

periodontal Periodontology or periodontics (from Ancient Greek , – 'around'; and , – 'tooth', genitive , ) is the specialty of dentistry that studies supporting structures of teeth, as well as diseases and conditions that affect them. The supporting ...

tissue is an important issue, which impacts the amount of force. Morill found out that masticatory muscles stop their contraction differently upon the appearance of pain signals from the periodontal tissue. Shreder used local

anaesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), am ...

to ignore the periodontal response to measure the maximum force of mastication. His research showed that a 21-year-old man without any periodontal

pathology Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in ...

who could produce approximately of force, increased the amount of that force to following local anaesthesia. Weber worked out that 1 cm² surface of perpendicular slide of any masticatory muscle can produce approximately force. The following surfaces were found *

– 8 cm² *

– 7.5 cm² * medial pterygoid – 4 cm² Thus, the total average surface area of perpendicular masticatory muscles slide is about .

Forces

Nankali studied chewing in multiple individuals. He found variation in the amount of masticatory force. The masticatory forces changes at eating time according to mouthful characteristic and size. This has various effects on the maxilla and mandible via the teeth. The periodontal system automatically controls the measure of mastication force. The jaw elevator muscles develop the main forces used in mastication. The force generated during routine mastication of food such as carrots or meat is about . The maximum masticatory force in some people may reach up to . The study of masticatory force in patients with polymyositis and dermatomyositis shows that hyposalivation and mucosal alterations can be related to the pathology of masticatory system.

Force distribution

Nankali systematized masticatory force distribution. According to this system, force is divided in two main groups, with physiological or pathological conditions. The physiological masticatory force is divided into three subgroups according to their localizations: anterior, general (covering the entire arch) and posterior part of arch, which is also divided into two different groups; unilateral and bilateral. Producing a maximum masticatory force uses the general subgroup of this systematization.

Masticatory muscles

Measuring masticatory force

Forces

Force distribution

References

Further reading