The idea that chewing gum can increase the size of the jaw is often fueled by the desire for a more defined facial structure. For the vast majority of people, chewing gum will not lead to substantial enlargement of the jaw. While the repetitive motion does engage the chewing muscles, any increase in muscle tone is usually minor. The overall shape of the jawline is determined by both the underlying bone structure and the size of the associated muscles.
The Jaw Muscles: What Chewing Engages
The process of chewing involves several powerful muscles that work together to move the lower jawbone. The most prominent is the masseter muscle, which is responsible for closing the jaw with considerable force. This muscle is located on the side of the face, running from the cheekbone down to the lower jaw.
When this muscle enlarges, a condition known as masseter muscle hypertrophy, it can create the appearance of a wider or more square jawline. The temporalis muscle, which is situated on the side of the head above the ear, is also involved in the chewing process. Both are part of the group known as the muscles of mastication.
These muscles are skeletal muscles, meaning they respond to stimulation and resistance similar to muscles in the arms or legs. Repetitive use or clenching can cause them to become overworked, which can sometimes lead to a noticeable increase in muscle bulk. This increase in size is a muscular change, not a change to the underlying bone structure.
Does Gum Provide Enough Resistance for Hypertrophy?
Muscle enlargement, or hypertrophy, requires high resistance and progressive overload. Chewing gum provides a relatively low level of resistance compared to eating tough, fibrous foods or performing intentional jaw exercises. Conventional chewing gum is designed to be soft and pliable, offering minimal challenge to the masseter muscle.
While some individuals who chew gum excessively may experience a slight increase in muscle tone, significant enlargement is relatively uncommon and often linked to other factors. A clinical trial found that six months of consistent gum chewing increased maximum occlusal force but did not lead to a statistically significant difference in masseter muscle thickness or mandibular shape in healthy adults. This suggests that the resistance provided by standard gum is insufficient to drive major muscle growth.
The appearance of a larger jawline due to muscle hypertrophy is highly dependent on genetic predisposition. For adults, the bone structure of the mandible, or lower jaw, is fully developed and will not change shape from chewing gum. Any perceived change in jaw size is purely a soft tissue change involving the muscle, not the bone. Some specialty gums are marketed with higher resistance to promote masseter growth, but the long-term effectiveness and safety of these products are topics of ongoing discussion.
Consequences Beyond Size: Excessive Chewing
While chewing gum may not dramatically increase jaw size, excessively frequent or prolonged chewing can lead to health issues. The repetitive motion places strain on the temporomandibular joint (TMJ), the hinge connecting the jawbone to the skull. Overuse can lead to temporomandibular joint dysfunction (TMD), characterized by pain, clicking, popping, or a restricted range of motion in the jaw.
Constant chewing can cause the jaw muscles to become fatigued, tight, or even spasm. This overuse contributes to tension headaches, as the masseter and temporalis muscles are strained for extended periods. Studies indicate that people who chew gum for more than three hours a day face a higher risk of developing TMD symptoms.
Some individuals unconsciously favor one side of their mouth while chewing, which can lead to muscular imbalances and uneven stress on the joints. For those who grind or clench their teeth (bruxism), excessive gum chewing can exacerbate the condition by keeping the chewing muscles constantly activated. Prolonged chewing may also increase wear on tooth enamel or strain existing dental work.