A tooth can be sensitive to cold or hot for many reasons. If you are getting symptoms, it always best to see a dentist to check what is the cause of your sensitive tooth. For all cases, the sensitivity to temperature is the nerve in the tooth pulp being triggered. If your pulp has a reason to be inflamed, this can happen all the time, for example with a cavity caused by tooth decay or a cracked tooth. Both of these cause inflammation in the pulp, making it “nervy”. However sometimes there is no reason for the nerve to be inflamed, yet you can still get sensitivity in the tooth. This is called dentine hypersensitivity and is due to exposed dentine, the tooth substance under the enamel. The most common sensitivity is to cold. Obviously, for Surry Hills and Darlinghurst residents that like Gelato Messina’s awesome gelato and ice cream, this can be a huge problem!
Why is my tooth sensitive to hot and cold?
Tooth sensitivity is caused by damage to the tooth, exposing the dentine. Exposed dentine can be caused by either recession of the gum, or damage to the enamel. It is usually a combination of factors that cause this, although which is the important factor varies from person to person.
Brushing hard, or using a hard toothbrush can cause abrasion of the tooth and recession of the gum. This is mechanical damage to the tooth and gums from repeated trauma to them, usually with your toothbrush. Avoid using hard toothbrushes, instead use a soft toothbrush or medium toothbrush with gentle pressure and a careful technique. Scrubbing your teeth hard just damages them, with no additional cleaning benefit. Abrasive toothpastes, such as whitening toothpastes, will worse this problem. Moreover as the enamel is further worn away, your tooth will actually appear darker and yellower. The enamel is the white part of your tooth and as you wear it down, you can see more of the dentine shining through, which is yellow. Some people even notice this and start to brush even harder, making it worse! Sensitive toothpastes are specially formulated to have low abrasion.
Acid wear causes the enamel to dissolve chemically. This is called erosion. At the gumline, the enamel is thinnest, so this area wears out completely first, exposing the dentine underneath. This worn area then spreads with further acids, causing a cratering of the tooth, or a little notch. Erosion can affect all surfaces of the teeth and sometimes there can be pitting of the occlusal surfaces, the biting surface of your tooth. Acids can be dietary, due to acidic food and drinks. This includes juices, fizzy drinks as well as citrus fruits, beer and wine. Acid wear and erosion can also be related to stomach problems, particularly for those who get heartburn or gastric oesophageal reflux. Asthmatics using a bad inhaler technique can also cause damage.
Clenching and grinding your teeth can also cause the enamel to get worn. The teeth rubbing over each other causes wear where the teeth meet each other. This is called attrition. During normal chewing and talking our teeth do not normally touch, but stop a little short of each other. In grinding the teeth rub over each other. This can occur daytime, for instance at times of stress or concentration. It can also occur in your sleep at night time. The flexing of your teeth under force can cause chipping at the neck of the tooth. This is called abfraction. Using your teeth in this way is usually a subconscious habit. Bruxism is the term for grinding.
Tooth whitening can also cause sensitivity, so is best carried out be a dentist to assess your risk. Other causes of sensitivity include a cracked tooth, dental decay, broken or lost fillings, as well as others. For this reason it is important to mention any symptoms when you see your dentist for your dental check up.
Is my nerve exposed? It certainly feels like it.
The nerve is not usually actually exposed. It just feels like the nerve is exposed as the cold sensitivity, in particular, can be quite severe. As well as being sensitive to cold and hot, the tooth can also be sensitive to touch, sensitive to brushing, sensitive to sweet things, sensitive to salty things and even sensitive to air, for instance breathing on a cold day. Those affected often avoid cold drinks or ice cream. After brushing, they rinse with tepid water rather than cold water.
The dentine has lots of tiny channels, called tubules, that extend from the nerve and pulp through the dentine. These tubules contain water. It is thought that the movement of the water inside these tubules is what causes the pain. Hot and cold things cause expansion of the water, triggering the nerve to feel pain. Air and salt cause movement in the water, so again, you feel pain. The severity of the pain can be much worse than the actual damage caused, which is why it is an exaggerated response. This is where the name dentine hypersensitivity comes from. The tooth is hyper sensitive to normal stimulants.
How can I stop the pain and sensitivity?
The first step to treating dentine hypersensitivity is treating the cause. Your dentist will discuss with you any habits, both deliberate and subconscious that you might have that is causing the problem. You should brush gently, with a soft or medium brush. Avoiding dietary acids and investigation of any stomach problems with your GP will reduce erosion. After consuming any dietary acids, it is important not to brush for at least 30 minute. Waiting up to an hour is even better. This allows your saliva to restrengthen your tooth, minimising the risk of abrasion from overbrushing. Any daytime grinding or parafunctional habits should be stopped and if there is night time bruxism, an occlusal splint should be worn. All of these changes will help prevent the problem from getting worse.
To manage the symptoms, sensitive toothpaste can be used. The potassium formula and microscopic silica particles help to desensitise the tooth and block the open tubules. This can take a few weeks to months of use. Application of a topical remineralising and desensitising agent, such as Tooth Mousse, is also effective. If these measures are insufficient, your dentist can apply a desensitising agent. For more moderate or severe cases, a bonded filling in the affected area both protects it from further damage and also acts as a barrier to stop the sensitivity to stimulants.