Tooth sensitivity is tooth discomfort in one or more teeth that is triggered by hot, cold, sweet, or sour foods and drinks or even by breathing cold air. The pain can be sharp, sudden, and shoot deep into the nerve endings of your teeth. Teeth become sensitive when the enamel wears out or gums recede exposing the nerve fibres to the external environment. The roots, which are not covered by hard enamel, contain thousands of tiny tubules leading to the tooth's nerve center (the pulp). These dentinal tubules (or channels) allow the stimuli -- for example, the hot, cold, or sweet food -- to reach the nerve in your tooth, which results in the pain you feel.
Tooth sensitivity is due to the wasting diseases of teeth, namely attrition, abrasion and erosion. These diseases cause loss of tooth structure causing the dentin nerve fibres to get exposed, thus triggering sensitivity. Gum recession is also another reason for hypersensitivity.
Dentinal hypersensitivity or cervical dentinal sensitivity, is a significant clinical problem. It is defined as pain arising from exposed dentine typically in response to thermal, chemical, tactile or osmotic stimuli. Hypersensitivity means a signal that the dentin is exposed and the pulp is vulnerable to damage.
Sensitive teeth mean that, one gets mild to severe discomfort for several hours. This is an early warning sign of more serious dental problems. The part of the tooth we see is covered by a layer of enamel that protects the softer dentine underneath. If the dentine is exposed, a tooth can become sensitive. This usually happens at the meeting place for the tooth and the gum meet, the enamel layer is thinner here.
Brushing too hard can cause enamel to be worn away, particularly where the teeth meet the gums. The freshly exposed dentine then become sensitive. Dental erosion is also caused by acid attacks from food and drinks. If enamel is worn away the dentine underneath is exposed, which leads to sensitivity.
Gums may recede (shrink back) exposing the roots and become more sensitive, as they do not have an enamel layer for protection. Build-up of plaque or tartar can cause the gum to recede and even destroy the bony support of the tooth. Pockets can form in the gums around the tooth thus worsening the problem. Tooth grinding is a habit which involves clenching and grinding the teeth together. This causes the enamel to be worn away, making the teeth sensitive.
A cracked tooth or filling This can run from the biting surface of a tooth down towards the root. Extreme temperatures, especially cold may cause discomfort.
Some patients have sensitivity for a short time during or after having their teeth bleached.
Treatment would be the sealing of the exposed tubules using agents in severe cases using dental cements or composites. It can also be reduced by using toothpastes specially made for sensitive teeth. Dentists also suggest application of fluoride sealant on the crown of the teeth. The sealant covers the exposed dentin and as a barrier against pain. If the above treatments are not effective then root canal therapy is recommended. This can make the tooth non vital to pain and protected by crowning it.
In severe cases the restoration of the tooth is done with dental cements or composites.