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Why does my tooth feel pressure when I bite it?

Have you ever bitten down on something hard like an ice cube or hard candy and felt an uncomfortable pressure or even pain in your tooth? This sensation is caused by the forces that are applied to the tooth when you bite down. Understanding why teeth feel pressure and pain during biting can help explain how your teeth work and why dental problems like cavities, cracked teeth, and root infections develop.

Human teeth are complex structures composed of multiple layers of mineralized tissues. Each tissue layer plays an important role. Here are the key anatomical components of a tooth:

Enamel

The outermost layer of the tooth made of the hardest substance in the body. Enamel is >95% mineral, with very little water or organic material.

It ranges from 2-3 mm thick and covers the visible crown portion of the tooth.

Enamel helps protect the inner tooth layers from bacterial acids and physical wear. It distributes bite forces across the underlying dentin.

Dentin

The layer immediately under the enamel that forms the bulk of the tooth structure.

Dentin contains 70% minerals like hydroxyapatite crystals reinforced with an organic collagen matrix. This gives dentin more flexibility than enamel.

It has tiny fluid-filled tubular structures leading towards the pulp that allow for sensory transmission.

Pulp

The innermost chamber filled with soft connective tissues, blood vessels, nerves, and lymphatic vessels.

The pulp provides nourishment to keep the tooth alive and sensory innervation.

It extends like a funnel down through the tooth roots. The openings at the root ends are called apical foramina.

Cementum

This bone-like calcified substance covers the dentin of the tooth roots.

It is softer than enamel and dentin but helps anchor the periodontal ligament fibers.

Cementum is produced continually to compensate for wear, keeping the attachment strong.

Periodontal ligament

The periodontal ligament is a dense fibrous connective tissue that essentially suspends the tooth in the jawbone socket and attaches via cementum.

This ligament has an excellent blood supply and contains mechanoreceptor nerve endings that provide sensory feedback.

It allows the tooth to withstand chewing forces and provides proprioceptive information about tooth positioning.

Why Do Teeth Feel Pressure When Bitten?

When you bite down, the force is transmitted through the enamel and dentin layers towards the pulp chamber. The pressure then compresses the soft pulp tissue, including the nerve fibers inside. This compression causes the nerve endings to fire and send signals indicating tooth pressure up to the brain via the trigeminal nerve.

The fluid in the dentin tubules also shifts, which bends and stimulates the nerve fibers near the pulp border to generate pressure sensations. Even slight stresses on the teeth may induce fluid flows inside the dentin that are perceived by the nerves.

The exact mechanisms that cause teeth to feel pressure include:

Force transmission

Enamel and dentin distribute and transfer bite force inwards towards the pulp chamber. This effectively squeezes the pulp.

Nerve compression

The pulp contains bundles of sensory nerves that are compressed by inward pressure on the tooth. This deformation of nerve fibers triggers electrochemical signals.

Fluid shifts

Pressure generates fluid shifts and flows inside dentin tubules and the pulp that stimulate nerve fibers.

Tooth deformation

Stress and strain deform the hard tooth structure slightly, activating nerve endings.

Periodontal sensation

Fibers of the periodontal ligament are also compressed and stimulated, contributing to pressure signals.

Odontoblast stimulation

The cells that line the pulp chamber (odontoblasts) may release signaling molecules in response to deformation, heightening nerve sensitivity.

Factors Affecting Pressure Sensation

Several factors can influence the intensity and location of the pressure feeling when biting down on a tooth:

Bite force

Harder bites exert more force and pressure on the teeth. More force equals more nerve stimulation.

Tooth health

Structural defects like cracks, caries, and large restorations reduce the enamel integrity. This results in less even force distribution and higher pressures on the pulp.

Restorations

Dental work like metal or ceramic fillings, inlays, onlays, crowns, bridges, and implants all transmit biting forces differently than natural tooth structure. More force may be placed on particular areas of the tooth, heightening sensitivity.

Occlusion patterns

The way the upper and lower teeth contact (occlude) affects how forces are distributed across and between teeth. Irregular contacts concentrate more pressure in certain areas.

Tooth type

The size, shape, and nerve density of different teeth affects pressure sensation. Incisors often feel more sensation than molars when loaded.

Age

As the pulp chamber naturally shrinks and dentin thickens with age, there may be progressively less sensation of pressure from biting.

Individual factors

People have varying levels of sensation in their teeth based on the neurologic structure. Some are just more sensitive.

Why is Pressure Sensation Important?

The ability to sense pressure and forces applied to our teeth is extremely important for several reasons:

Biting and chewing adjustment

Pressure provides feedback to the brain, allowing you to subconsciously adjust bite force and chewing to prevent damage to teeth. You bite hard enough to chew effectively but not so hard as to fracture teeth.

Tactile information

Along with touch receptors in the tongue, lips and cheeks, tooth pressure contributes to the detailed sensory information about food objects in the mouth. This guides positioning for effective chewing.

Dental disease detection

Unusual pressure sensations can provide an early warning of underlying dental problems like cracks, leaking fillings, or pulp inflammation. Catching issues early prevents more extensive damage.

Tooth vitality sensing

Monitoring nerve vitality through electric pulp testing relies on the teeth sensing pressure and transmitting those signals. A lack of sensation indicates the tooth pulp may be necrotic or compromised.

Protective neural reflexes

Extreme pressure sensed by the pulp nerves triggers reflexes to rapidly open the jaws and avoid fracture or periodontal injury.

Tooth eruption and development

Forces sensed by the periodontal ligaments help guide the emergence of teeth into proper alignment. Proper occlusion depends on this feedback.

When to Seek Help

While minor temperature or pressure sensitivity is common and not concerning, you should consult your dentist promptly if you experience:

Persistent sensitivity lasting more than 2-3 weeks

Pain that disrupts sleep or eating

Sensitivity with no apparent cause like cracks, erosion, or gingival recession

Sudden sharp sensitivity while drinking hot or cold fluids

Loosening teeth or changes in occlusion

Swelling of gums indicating potential infection

Any mouth pain that cannot be explained

Getting evaluated quickly allows early intervention before major pulp or root damage occurs. Not all sensitivity requires immediate treatment, but a dentist can monitor it for changes over time.

Conclusion

The sensation of pressure when biting arises from the innervation and force transmission properties of the tooth structure interacting with the oral environment.

This sensitivity is important for controlling bite forces, detecting dental issues early, and preserving tooth vitality.

Loss of pressure sensation can have serious consequences like excessive biting, unchecked infections, and unnecessary tooth loss.

Restorations aim to prevent damage in numb teeth or regenerate some sensory function.

In other cases, sensitivity results from exposed dentin rather than actual pulpal damage. Dietary acids, gum disease, and bruxism often contribute to this type of sensitivity.

Managing factors like brushing habits, enamel wear, and occlusal strains can help reduce discomfort from pressure sensitivity.

Severe or persistent sensitivity should be promptly evaluated by a dentist to check for underlying disease.

The intricacies of tooth anatomy and neurology determine the sensations perceived during biting and chewing. With proper home care and professional dental treatment, your natural pressure detectors can remain sensitive yet resistant to damage for decades to come.

(09/02/2024)
by CDHP Dental Health Project

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