The question of whether back teeth should touch is a common source of confusion, largely because the answer changes depending on what the jaw is doing. Dentists refer to how the upper and lower teeth meet as occlusion. Your back teeth should only touch briefly and lightly during active functions, remaining slightly separated the rest of the time. Whether your teeth are meeting healthily depends on if your jaw is in a state of rest or function.
The Ideal Resting Position
In a healthy individual, the jaw and its associated muscles are designed to be in a relaxed state for most of the day, a condition known as the physiological rest position. During this time, the back teeth should not be in contact. A small vertical gap should exist between the chewing surfaces of the upper and lower teeth, referred to as the freeway space, or the interocclusal rest space.
This space is typically between 2 to 4 millimeters when the jaw is relaxed and the person is sitting upright. Maintaining this separation allows the powerful jaw muscles to rest and recover from chewing and speaking. If the teeth were constantly touching, the muscles would be perpetually strained, which can lead to discomfort and fatigue. The freeway space also helps protect the temporomandibular joints (TMJs) and the tooth enamel by preventing constant wear.
Essential Moments of Functional Contact
While the resting state requires separation, there are specific moments when the back teeth are designed to touch. The primary function requiring contact is mastication, or the process of chewing food. Molars and premolars are shaped to grind food into smaller, swallowable pieces, requiring forceful, momentary contact. During chewing, rhythmic jaw movements bring the cusps of the upper and lower teeth together to crush and shear the food bolus. Contact also occurs briefly during deglutition, or swallowing, helping to stabilize the lower jaw against the skull and providing a firm base for the swallowing muscles.
Understanding Excessive Contact
Excessive or prolonged contact between the back teeth, occurring outside of chewing and swallowing, represents a pathological state. The most common form is bruxism, the involuntary clenching or grinding of the teeth. This habit can occur while a person is awake (awake bruxism) or while they are asleep (sleep bruxism). Awake clenching often happens during periods of concentration or tension, while sleep grinding can be particularly forceful.
The consequences of this excessive contact are both immediate and long-term. Constant grinding wears down the protective enamel layer, leading to flattened surfaces and increasing tooth sensitivity. The immense forces can cause teeth to chip, fracture, or become loose, and damage existing dental restorations. Sustained muscle activity can also result in chronic muscle fatigue, frequent tension headaches, and the development of pain and dysfunction in the jaw joint, referred to as Temporomandibular Joint Disorder (TMD).
When to Seek Professional Guidance
You should consult a dentist or specialist if you notice symptoms suggesting your back teeth are contacting too often or too forcefully. Common signs include waking up with soreness, stiffness, or pain in the jaw, temples, or face. Headaches that start near the temples and occur frequently in the morning are also a strong indicator of sleep bruxism.
Other physical signs requiring professional attention include visible damage to the teeth, such as chips, cracks, or increased sensitivity to hot and cold. A clicking, popping, or grating sound when moving the jaw, or difficulty opening or closing the mouth, suggests a problem with the temporomandibular joint. A dentist diagnoses excessive contact through physical examination, assessing wear patterns, and feeling jaw muscles for tenderness. Common non-surgical treatments include custom-fitted night guards, which protect the teeth and help distribute force evenly across the jaw.