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Grinding and Clenching

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Why do people grind their teeth?

You can tell someone grinds their teeth by looking at the biting surfaces. It may look smoothed down in particular spots as if someone had consistently rubbed sandpaper over the surface. Usually, this is done subconsciously during the night, and the force is much stronger than one would grind during the normal eating process. The contributing factors can be varied. 


Some common reasons: 


- Dysfunctional bite

- Sleep Disordered Breathing, Upper Airway Resistance, or Obstructive Sleep Apnea

- Improper tongue placement, causing the tongue to be between the teeth. This area needs more research, but the theory states that a low tongue posture, where the tongue rests partially or fully on the teeth during the night, can result in a reflexive impulse to bite down/grind what is between the teeth (which would normally be food). 

- Can be a symptom of parasitic infection, reflux, and is present in those with neurological or sensor-neural disorders

- Correlation found with patients who grind and tongue-tie issue (tethered oral tissue under the tongue)


Dental splints or night guards can be worn on the upper or lower arch. This appliance creates a smooth surface, much like a skating rink for the teeth to glide against to help prevent against further wear of the tooth surface. Unfortunately, splints/night guards are more of a band-aid than a cure. A thorough assessment should be performed to determine the root cause of this negative night-time habit.


Grinding the teeth assists the body in regaining homeostasis following an apnea episode. (Dr. Darick Nordstrom, DDSIf airway issues pose a problem during the night, often due to the tongue and other soft tissue falling back into the airway, our bodies are equipped with self-preservation mechanisms. We are hard-wired to maintain the essential task of breathing, even if those mechanisms have negative consequences. While grinding, the tongue moves forward, out of the airway space, but unfortunately, it maintains a low position. This low position causes a multitude of problems, including altering how the face, mouth, and sinuses develop, and how a person has a tendency to breath (a low tongue posture can lead to breathing through the mouth). According to the Journal of Dental Sleep Medicine; Link between Sleep Bruxism, Sleep Disordered Breathing and Temporomandibular Disorders - Balasubramaniam et al. in addition to wearing away teeth, grinding can cause tension or pain in the face and jaw muscles, tooth chipping, fracture, and mobility, dry mouth, failure of dental implants due to excessive forces, hypersensitivity to hot and cold, scalloped tongue, and exacerbation of periodontal disease.* 


*controversial issue - commonly associated with bruxism by clinicians, based on clinical experience, but more research is needed to determine cause and effect.

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Why do people clench their teeth?

Almost everyone who grinds their teeth also clenches, but not everyone who clenches their teeth also grinds. Unlike grinding, which takes place primarily at night, clenching can occur anytime during the day or night. Increased clenching and grinding has traditionally been correlated to stress. According to the Registered Dental Hygienist Magazine (United States), when we clench, a small amount hormone called oxytoxin is released (the same hormone that is released during a hug). This habit, unfortunately, has negative side affects. The symptoms are similar to grinding - head aches and tension, or pain in the face/ jaw muscles.


Almost everyone who clenches, has stress - but not everyone who has stress, clenches. The most accurate causation factor for clenching is the lack of space between the upper and lower molars. This space, called "free-way space," should ideally be 2-3mm apart. When there is a lack of space, it usually results in clenching. When there is too much space, it presents as the lips slightly separated, often resulting in mouth breathing. It is difficult for the body to constantly maintain a proper freeway space, unless the muscles, especially the tongue, are in their proper oral posture and preforming functionally. 


Bone grows in the presence of pressure. A common sign in those who grind or clench are bony protrusions along the ridges of the upper and lower jaws due to the excessive forces applied to the bones. These are called tori or exostosis. Their presence is significant and is recorded during an orofacial myofunctional assessment. 

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