The What and Why of Tooth Pain

To understand the concept of tooth pain, it is important to first understand the structure of tooth.

The tooth has three major layers:

1. Enamel – It is the outermost covering of the tooth and is is avascular and non-nervous.
2. Dentine – This layer is situated in between the outer enamel and the innermost pulp layer. This layer is well supplied with sensory nerves and responds well to the stimuli.
3. Dental Pulp – This is the innermost layer of dental pulp and is abundant in blood vessels and nerves. This layer is responsible for the reaction of tooth to various external stimuli.

The food that we consume (refined carbohydrates),is detrimental to the dental health.

The food in it’s various attributes, affect the tooth health. These attributes are –

i. form (carbohydrates) – refined carbohydrates are acted upon by some bacteria, already present in the mouth. This produces acids in the mouth, thereby creating a drop in pH values and causing mineral dissolution of the teeth.

ii. frequency of sugar intake – plays an important role in causing tooth decay.

iii. consistency (stickiness and viscosity) – sticky foods (banana, eclairs, etc) are more cariogenic (decay causing) as clearance from the pits and fissures of the teeth is difficult.

iv. time of intake (after meals or in between meals) – consumption of sugars with meals is better than in between meals. Sugar intake in between meals leads to continuous drop in the pH values of the mouth which further enhances the mineral dissolution.

Superficial Cavities

Inadequate tooth cleaning leads to initiation of bacterial activity on the food residue.

This leads to dissolution of the mineral content of the tooth and eventually a breakdown of the organic matrix of the tooth enamel.

This marks the beginning of tooth cavitation.

These cavities are often called “Incipient cavities“. They often appear as bluish-black lesions beneath mostly unaffected enamel.

Since, dental enamel is a non-nervous tissue, at this stage, the patient experiences no symptoms.

The lost tooth structure can be replaced by dental restorative materials.

Early Dentinal Caries

As the carious decay approaches the superficial layers of dentin, there are changes in the hydrodynamic movement of the dentinal fluid, within the dentinal tubules (Hydrodynamic Theory of Dentin sensitivity).

These fluid changes manifest as tooth sensitivity to the patient.

This sensitivity is describes as a “short, sharp, shock” like pricking pain, lasting only for the duration of externally applied stimulus. This pain subsides on removal of the stimulus.

The pain is caused due to:

1. Transmission of pain producing stimuli as a result of opened dentinal apertures, often associated with abrasion, erosion and root planing.
2. Pain maybe due to sour substances (Citric, concentrated solution of salt or sugar). These substances dehydrate the dentinal tubules by means of OSMOSIS and hence, cause rapid outward movement of dentinal fluid. This causes deformation of nerves within the tubules.

This Hyper-reactive dentin is more sensitive to the pulp tester, that is, they require lower levels of electrical stimulation.

Late Dentinal Caries

With the progressing decay, the deeper layers of dentine, closer to the dental pulp are affected.

This produces a prolonged painful response, caused due to external stimulus.

This is also called “Reversible Pulpitis” or “Hyperalgesia”

The Hyperemic response in a localised part of the pulp maybe accompanied by incipient inflammatory response, which maybe mild to moderate.

This is an initial and potentially reversible pulpal response.

This localised increase in the inflammatory response, leads to an increase in the intra pulpal pressure.

Hyperemia maybe accompanied by Hypersensitive dentin but the presence of hypersensitive dentin does not mean the presence of Hypermia

Treatment of such a condition is aimed at blocking the opened dentinal tubules. There are various ways to achieve this:

Desensitising Agent – Compounds like pottasium nitrate, strontium chloride present in various desensitising tooth pastes like “Protect”, “Sensodyne” and “Thermodent” produce calcium oxalate/ strontium phosphate crystals of different particle sizes within the tubules. It’s effectiveness of a single application lasts for upto 6 months.

Flouride Iontophoresis – A 2% solution of sodium flouride is used to block the open dentinal tubules.

The other modality is to remove the decay and replace the lost tooth structure with a filling material. This enables the removal of infection and preserves the health of the underlying pulp.

Irreversible Pulpitis

As the decay progresses further, the dental pulp becomes irreversibly inflamed. These inflammatory changes cannot be treated with a dental filling and needs treatment of the pulp itself – Root Canal Treatment.

The pain at this stage is unbearable. The tooth is more sensitive to heat than to cold. Sipping on to ice makes the pain better.
The intrapulpal pressure within the closed dental pulp increases and is reflected as DENTAL PAIN.

Further delay in the treatment may cause the pain to reduce in intensity, leading to ‘gnawing’ sort of pain and a discomfort in eating and chewing. This condition may also lead to a swelling around the tooth which may be uncomfortable.

The tooth gives visual and perceptual warnings at every stage of infection. Treatment is based on the stage you visit your doctor.

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