Dentin hypersensitivity is dental pain which is sharp in character and of short duration, arising from exposed dentin surfaces in response to stimuli, typically thermal, evaporative, tactile, osmotic, chemical or electrical; and which cannot be ascribed to any other dental disease.
Many of us say we have “sensitive teeth.” We usually mean that we feel twinges of pain or discomfort in our teeth in certain situations. These may include:
- Drinking or eating cold things
- Drinking or eating hot things
- Eating sweets
- Touching the teeth with other teeth or the tongue
There are two types of tooth sensitivity:
Dentinal sensitivity occurs when the dentin (middle layer) of a tooth is exposed. Normally, the dentin is covered by enamel above the gumline and by cementum below the gumline. Dentin contains tiny openings called tubules. Inside each tubule lies a nerve branch that comes from the tooth’s pulp (the nerve center of the tooth). When the dentin is exposed, cold or hot temperature or pressure can affect these nerve branches. This causes sensitivity.
Dentin becomes exposed when the outer protective layers of enamel or cementum wear away. This can affect one or more teeth. Some causes of dentin exposure include:
- Brushing your teeth too hard. This can wear away the enamel layer.
- Poor oral hygiene. This may allow tartar to build up at the gum line.
- Long-term tooth wear
- Untreated cavities
- An old filling with a crack or leak
- Receding gums that expose the tooth’s roots. Receding gums often are caused by periodontal diseases or by brushing too hard.
- Gum surgery that exposes a tooth’s roots
- Tooth whitening in people who have tooth roots that already are exposed
- Frequently eating acidic foods or drinking acidic liquids
Pulpal sensitivity is a reaction of the tooth’s pulp. The pulp is a mass of blood vessels and nerves in the center of each tooth. Pulpal sensitivity tends to affect only a single tooth. Causes include:
- Decay or infection
- A recent filling
- Excessive pressure from clenching or grinding
- A cracked or broken tooth
If you feel a sharp pain upon biting, you may have a broken or cracked filling. Pain when you release a bite is a sign of a cracked tooth.
The pain is sharp and sudden, in response to an external stimulus. The most common trigger is cold, with 75% of people with hypersensitivity reporting pain upon application of a cold stimulus. Other types of stimuli may also trigger pain in dentin hypersensitivity, including:
- Thermal – hot and cold drinks and foods,cold air, coolant water jet from a dental instrument.
- Electrical – electric pulp testers.
- Mechanical–tactile – dental probe during dental examination, periodontal scaling and root planing, toothbrushing.
- Osmotic – hypertonic solutions such as sugars.
- Evaporation – air blast from a dental instrument.
- Chemical – acids, e.g. dietary, gastric, acid etch during dental treatments.
- The frequency and severity with which the pain occurs are variable.
Your dentist will look at your dental history and will examine your mouth. You also will need X-rays to show if there is decay or a problem with the nerve. The dentist will ask about your oral habits. Grinding or clenching your teeth can contribute to sensitivity. Your dentist also will look for decay, deep fillings and exposed root surfaces. He or she may use an explorer — a metal instrument with a sharp point— to test teeth for sensitivity.
A tooth may be sensitive to cold for several weeks after you get a filling. The metals in amalgam (silver) conduct the cold very well, transmitting it to the pulp. Bonded (tooth-colored) fillings require etching the tooth with acid before the filling is placed. In some cases, this etching removes enough enamel to make the tooth sensitive. However, advances in bonding now make it less likely to cause tooth sensitivity.
Your dentist or endodontist can do tests to see if you need root canal treatment.
If your tooth becomes sensitive after a deep filling is placed, the problem may go away in several weeks. Sometimes the filling is too high. That puts too much pressure on the tooth when you bite down. Your dentist can reduce the height of the filling. If the sensitivity does not go away over time, the tooth probably needs a root canal.
Sensitivity in more than one tooth may disappear in a short time or it may continue. It depends on the cause of sensitivity. Every case is different. Some people have sensitive teeth for only a month or two. Others have the condition for years.
Dentinal sensitivity — You might be able to reduce your chances of dentinal sensitivity by:
- Brushing twice a day and flossing daily
- Using a soft or ultrasoft toothbrush and brushing gently up and down, rather than side to side
- Using a fluoride toothpaste and mouth rinse
- Using a toothpaste that provides protection against sensitivity
- Getting treatment for grinding or clenching your teeth (bruxism)
Pulpal sensitivity — If a tooth needs root canal treatment, there is no good way to prevent pulpal sensitivity other than to get the needed treatment. Delaying root canal treatment is not recommended. It may result in further problems.
Dentinal sensitivity is quite treatable, whatever the cause.
Your dentist or dental hygienist will clean your teeth. If your teeth are too sensitive to be cleaned, your dentist may use a local anesthetic or nitrous oxide before the cleaning.
After a cleaning, your dentist may apply a fluoride varnish to protect your teeth. This temporarily reduces sensitivity. It also strengthens your teeth. Your dentist may apply an in-office treatment for sensitivity. These products block the openings (tubules) in dentin and reduce sensitivity. A newer approach is to use a dental laser. The laser treatment also alters the tubules to reduce sensitivity.
Using fluoride toothpastes and fluoride mouth rinses at home will help to reduce sensitivity. You also can buy toothpastes just for sensitive teeth.
Talk to your dentist about which fluoride rinses you should use. Some over-the-counter rinses are acidic. Others are not. You should choose a fluoride mouth rinse that uses neutral sodium fluoride.
Pulpal sensitivity will be treated with a root canal if the tooth’s nerve is damaged or dying. Your dentist will remove the nerve and place a non-reactive substance (gutta percha) in the space where the nerve was. The tooth no longer will have a continuous barrier of enamel to protect it. Therefore, it will be restored with either a composite filling or a crown.
To reduce pain due to grinding or clenching, the dentist will make a plastic night guard. Use the guard while you sleep.
When To Call a Professional
If sensitivity lasts for longer than a few weeks, contact your dentist. If you have a scheduled cleaning coming up soon, talk to your dentist then about your sensitivity. Most cases of tooth sensitivity are easy to treat.
The outlook is different depending upon the cause of the sensitivity.