Introduction

Definition of tooth pulp and its importance in dental health

The tooth pulp is a tissue in the centre of the tooth containing nerves and blood vessels. The tooth pulp keeps your tooth alive; without the pulp, the tooth is dead. The blood vessels within the pulp are crucial in providing nutrients to our teeth, such as oxygen and glucose, and removing any harmful waste products. Your tooth pulp’s role in dental health extends further to helping repair any damage to the gums surrounding your teeth, as well as repairing dentin, the softer tissue underneath our teeth’s enamel.¹

Anatomy of tooth pulp

Location within the tooth

The tooth pulp lives within the centre of the tooth and is the innermost layer. Surrounding the tooth pulp is a layer of dentin, and the outermost layer of the tooth is enamel, which we can see.² The below image shows the anatomy of the tooth:

The tooth pulp is composed of nerves, blood vessels, and loose connective tissue, which is produced by specialized cells known as fibroblasts. The anatomy of the tooth pulp can be divided into the following four sections:

Nerve and blood supply

Many blood vessels and nerves supply the dental pulp. The blood supply to the tooth pulp arises from small branches of an artery, known as arterioles, which branch to the smallest blood vessels in the body, which are known as capillaries. The network of capillaries usually remains under the odontoblastic layer of the tooth.²

The tooth pump is innervated by the fifth cranial nerve called the trigeminal nerve. The nerve cells (neurons) enter the pulp via the bottom of the tooth via a structure known as the apical foramen, and these neurons branch off to form the nerve plexus of Raschkow (which is a network of intersecting nerves). The nerve supply of the pulp is made up of two different nerve fibres, known as A fibres and C fibres, which have the following roles:

Functions of tooth pulp

Sensory function

The nerves in the dental pulp have a sensory function that detects any changes in temperature and pressure. Surrounding the pulp is a structure called dentin, which is made of thousands of very small fluid filled channels called dentinal tubules. When the tooth detects a change in temperature or pressure the fluid that resides in these tubules moves to the pulp. The fluid places pressure on the nerves within the pulp, which in turn causes tooth sensitivity.

Transmitting pain signals

As previously discussed, the nerve fibres within the pulp can be A-fibers, which send signals to the brain when a hot or cold stimulus is applied to the tooth, resulting in shooting pain. There are also C-fibers, which can cause us a dull, aching pain. C-fibers respond to much more intense stimuli, such as hot and cold. Signals from these nerve fibres are transmitted from the pulp via the trigeminal nerve to the brain stem to a part of the brain known as the trigeminal nuclei, where the signal can be interpreted by our brain.⁵

Nutrient supply

As mentioned previously, our dental pulp has lots of blood vessels, which keep blood flowing to the tooth, providing nutrients such as oxygen and glucose. This also prevents the tooth from becoming brittle by keeping the tooth rich with nutrients.

Formation of dentin

The pulp also has a role in the formation of dentin, which is what surrounds the dental pulp. When our teeth experience trauma the pulp forms reparative dentin in response .

Role in dental health

Response to dental injuries

If the pulp is damaged, the initial response is inflammation. If the inflammation is left untreated, this will result in pulp necrosis (death of the pulp) and infection. The inflammation will also begin to spread to the alveolar bone in the mouth.⁶

Pulpitis and its causes

Pulpitis can be caused by having a dental cavity. This allows bacteria to enter the tooth and get into the pulp, resulting in inflammation, which is known medically as pulpitis. As mentioned previously, if left untreated this can result in pulp necrosis. Pulp necrosis is where the pulp tissue dies.

As well as dental cavities, there are other causes of pulpitis, which include:

• A cracked tooth
• Tooth injury
• Dental procedures- which are unsuccessful, or multiple dental procedures that  weaken the tooth and make it  susceptible to bacteria entering the pulp
• When the enamel of the teeth is worn, it exposes the dentin of the teeth, allowing bacteria to enter the teeth and the pulp. Wearing down the enamel can occur when you grind your teeth together or brush your teeth too hard, eroding the enamel.

Common dental issues related to tooth pulp

Tooth decay and pulp involvement

Tooth decay begins with the initial demineralization of enamel, where minerals such as calcium and phosphate are removed from the enamel and broken down by acid. If this process is allowed to continue, it results in enamel decay, where black/brown cavities begin to form. Once the enamel has decayed, the tooth dentin is exposed. Dentin is much softer than enamel, and the process of decay here is much faster. Once the dentin has decayed, it exposes our pulp, which is what keeps the tooth alive and causes tooth pain due to the nerves in the pulp. Here, the pulp will start to become irritated and inflamed. Visible symptoms of pulp decay include swelling and pressure from the swelling on the nerves, which can cause pain. As the pulp decay continues, this may result in bacteria entering the pulp, causing an infection. Infections can result in further inflammation and lead to an abscess filled with pus forming at the bottom of the tooth. If you suspect that you have a tooth abscess, you should see your dentist immediately as the infection may spread to other areas of the body, including the head and neck, and treatment may involve removing the infected tooth.

Root canal infections

A root canal removes the dental pulp, including blood vessels, nerves, and connective tissues. Root canal is performed when the pulp has become either infected or has been subject to tooth decay. Root canal infections are rare and may occur due to many different reasons. If pain persists  one week after root canal treatment, this may indicate an infection and you should seek out advice from your dentist.

Pulpitis and its symptoms

If you have pulpitis, the tooth pulp will be inflamed, and it usually arises when the tooth becomes irritated or contracts an infection due to bacteria entering the tooth via a crack or a cavity. There are two different types of pulpitis, which are listed below:

• Reversible pulpitis, which a dentist can treat using a filling
• Irreversible pulpitis, which will lead to the death of the pulp (pulp necrosis)

Symptoms of both reversible and irreversible pulpitis include sensitivity to cold. However, for reversible pulpitis, there is no pain when the dentist taps the infected tooth, but pain is present if this is irreversible pulpitis. Those with irreversible pulpitis also experience sensitivity to heat as well as cold.

Diagnosis and treatment

Clinical examination for pulpitis and tooth decay

When you are suspected to have a condition such as pulpitis the dentist will examine your teeth to see where the tooth decay has occurred.

X-rays and imaging for pulpitis and tooth decay

Clinical examinations can only take the dentist so far when diagnosing pulpits, and they will use X-rays to see the extent of the tooth decay through the pulp and the level of inflammation.

Root canal therapy

Root canal treatment is necessary when X-rays show that the pulp has been inflamed due to a bacterial infection, which can occur as a result of tooth decay reaching through to the tooth pulp. The pulp that has been infected is removed to save the tooth during a root canal treatment. 

Pulpotomy and pulp capping

A pulpotomy is a procedure performed on both adults and children when the pulp has become subject to tooth decay, but it is more common in children. During a pulpotomy only the pulp that is in the crown of the tooth is removed. The crown is the visible part of our teeth. Any remaining pulp in the root canal remains (Very Well Health).

Pulp caps may be used when the enamel and dentin of the tooth have decayed, but the tooth remains healthy. There are two different types of pulp cap:

Tooth extraction as a last resort

As a last resort, those with irreversible pulpitis may opt to have the infected tooth removed and [possibly have a dental implant or bridge.

Prevention of tooth pulp problems

Good oral hygiene practices

Brushing your teeth twice and flossing every day are good hygiene procedures.

Regular dental check-ups

Seeing your dentists regularly for check-ups and teeth cleaning can help diagnose any tooth pulp conditions early and spot tooth decay, preventing it from spreading to the pulp.

Avoiding excessive sugar intake

Bacteria in your mouth feed on the sugar we eat and produce acids that erode the enamel on our teeth, starting tooth decay, which may spread to the dentin and then the tooth pulp. Avoiding excessive sugar intake prevents the formation of cavities and the decay spreading to the pulp.

Summary

• The tooth pulp is the innermost structure of the tooth, containing nerves, blood vessels, and connective tissue.
• The tooth pulp is what keeps the tooth alive, and detects any pain, transmitting pain signals to the brain.
• The tooth pulp has a regenerative role in the tooth, produces reparative dentin in the event of trauma and nourishes the tooth.
• A lack of proper dental care, including brushing, flossing and avoiding high-sugar contact, can result in tooth decay reaching the pulp.
• Tooth decay reaching the pulp makes the tooth susceptible to infection from bacteria, and this can lead to pulpitis.
• Diagnosis of pulp-related issues involves clinical examinations and X-rays
• Treatment for pulpitis is typically root canal treatment