The average adult has 32 teeth (16 up and 16 down). A tooth has three sections (crown, neck and root) and four main parts:- enamel, dentine, cementum and pulp. The enamel is the strongest structure in the human body; it has neither blood vessels nor nerves. It is the part of the tooth that is exposed with its colour varying from light yellow to grayish white. Underneath the enamel is the dentine; this is softer than the enamel but harder than bone. The dentine covers the pulp which has a lot of blood vessels and nerves. The dentine has no nerves but it has a lot of tiny tubules/channels which lead to the pulp. Through these tiny tubules the pulp which has a lot of nerves is exposed to temperature changes, food and liquids. In other words 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 occurs when the underlying layer of your teeth –the dentin – becomes exposed.
1. Brushing too hard.
Tooth brushes can be hard, medium or soft. Using hard brush and brushing your teeth too vigorously for a long time can wear down enamel and cause the dentin to be exposed. It can also cause recession of the gums (the gum tissue pulls away from the teeth). This is more likely to occur if you brush twice a day.
2. Tooth decay near the gum line.
Tooth decay occurs when foods containing carbohydrates (sugars and starches), such as breads, cereals, milk, soda, fruits, cakes, or candy are left on the teeth. Bacteria that live in the mouth digest these foods, turning them into acids. The bacteria, acid, food debris, and saliva combine to form plaque, which clings to the teeth. The acids in plaque dissolve the enamel surface of the teeth, creating holes in the teeth called cavities.
3. Gum Recession due to Periodontal disease etc.
Gum recession can be due to conditions such as periodontal disease, and vigorous tooth brushing over a long period. The gum is the red layer that covers the root of the tooth, with gum recession (the gum tissue pulls away from the teeth) the root surface becomes exposed. The roots, which are not covered by hard enamel, contain thousands of tiny tubules leading to the tooth’s nerve center (the pulp). This causes tooth sensitivity.
4. Gum disease (gingivitis).
Inflamed and sore gum tissue may cause sensitivity due to the loss of supporting ligaments and gum recession which expose the root surface that leads directly to the nerve of the tooth.
5. Cracked teeth.
Chipped or broken teeth may expose the dentine which has a lot of tiny tubules connected to the pulp which contains a lot of nerves as stated above.
6. Acidic foods.
Regular consumption of foods with high acid content such as oranges, tomatoes, and tea can cause enamel erosion.
7. Poor Dental Hygiene.
Bacteria can work on the sugar in the mouth to form thick substances (plaques) that stick to the teeth. These plaques in turn aid the activities of the bacteria to create more cavities.The presence of plaque on the root surfaces can cause sensitivity. Good oral practice removes food debris from the mouth.
8. Dental Treatment/Care
Tooth-whitening products such as hydrogen peroxide may be major contributors to sensitive teeth. They could erode the enamel and dentine.
Some over-the-counter mouthwashes which contain acids if used over a long period can worsen tooth sensitivity if you have exposed dentin. The acids further damage the dentin layer of the tooth.
Sensitivity can occur following teeth cleaning, root planning, crown placement, and tooth restoration but this does not last more than six weeks.