Most of us have experienced a sharp “zing” in a tooth while chewing or biting something hard like ice, candy, or a popcorn kernel. That sudden “zing” causes our jaw muscles to instantly stop contracting and activate the jaw opening muscles unconsciously. That reflex is one of the strongest in the body and is part of a protection of the mouth – being a means of survival by eating, breathing, and speaking.
The zing in our teeth is a small fracture that either injures the tooth nerve or flexes the tooth (yes, teeth can flex just like steel) which irritates the nerve. It takes a tremendous amount of force to crack an intact tooth (one without a filling). Cracked teeth are typically painful/sensitive to cold (81%). Pain with biting down (intermittently) is the second most common symptom (35%) of a cracked tooth and spontaneous pain (28%) is the third symptom of a cracked tooth according to a study in the Journal of Dentistry Dec 28, 2017. Cracks can be difficult to find and repair. Sometimes the tooth requires a crown and/or root canal.
What can cause a tooth to crack?
Sometimes we can crack teeth from bruxing or clenching. These unconscious forces often happen during sleep when our reflexes aren’t fully intact to protect the teeth. Teeth with fillings of varying size are more prone to fracture while chewing or clenching/grinding at night.
2/3rds of patients report cracked teeth were from grinding or clenching at night, the study reports. Nighttime clenching/grinding are one of the most common signs of a Sleep Breathing Disorder such as sleep apnea or some of the variant sleep breathing disorders. Activating the jaw closing muscles during clenching or bruxing stiffens the airway and can quickly open it during an apnea (airway closure while sleeping) event or hypopnea (partial closing).
If you clench your teeth or have cracked teeth from clenching your dentist probably made you a nightguard to protect the teeth. Nightguards have been shown in studies (previously written about this) to worsen sleep breathing disorders thereby increase clenching and bruxing (grinding teeth). If you have cracked teeth, wear a nightguard and find you bite harder on that than without, you are likely to have an underlying sleep breathing disorder that is causing the clenching and grinding.
