9 Reasons You Have Tooth Sensitivity

Unsurprisingly, tooth sensitivity has many causes and these are the most likely causes.

1. Gum recession (without gum or periodontal disease)
2. Gum recession in the presence of gum disease or periodontal disease
3. After new filling or crown
4. Leaking from an Old Crown or an old filling
5. After the placement of a new white filling or a composite filling
6. Dental decay or caries
7. After scale and polishing or a course of gum treatment
8. After a tooth whitening treatment
9. Tooth wear

We will look at the above causes of sensitive teeth in more detail. But first, we will talk about:

How teeth become sensitive from an anatomical and physiological perspective

The mechanism of tooth sensitivity.

In very simple terms, a tooth is made up of three different structures. These structures are the enamel, the dentine and the dental pulp.

Tooth enamel is the hardest substance in the body and it is a hard crystalline structure consisting of hydroxyapatite crystals.  Tooth enamel does not have a nerve supply. This means that any damage to the enamel is not painful however any Sensation from the enamel can be transmitted or conducted to the underlying tooth structure which does have a nerve supply. The underlying tooth structure consists of dentine dental pulp.

Tooth dentine

Tooth dentin is also a hard substance like enamel but it is not quite as hard as enamel. It is probably more like the structure of bone. Unlike tooth enamel, tooth dentine does Respond to stimuli such as heat, cold, sweet and pressure. The mechanism for this can be described as the following. Tooth dentine is not a uniform structure and microscopically it contains thousands of tubes called dentinal tubules.  The dentinal tubules run from the centre of the tooth where the pulp is, to the outside where the enamel is.  The dentinal tubules contain fluid. It is the movement of this fluid in response to stimuli that causes a response into the pulp which then gets registered as pain.  In very simple terms, tooth sensitivity is just an expression of dental pain. Dental pain can obviously have various degrees from extremely mild to agonisingly painful.

The dental pulp

This is commonly described as the nerve of the tooth. Dental pulp consists of nerves, lymph vessels and blood vessels. It provides information to the brain on the state of the tooth and any stimuli subjected to it including heat, cold, pressure, pain and sweet.

Tooth sensitivity, therefore, occurs when there is any movement of fluid within the dental tubules. Tooth sensitivity may be transmitted directly onto the tooth dentine or indirectly via the tooth enamel.

Most causes of tooth sensitivity occur when the dentine of the tooth is stimulated directly. This can occur when the enamel is very thin or the enamel is breached.

Cervical sensitivity.

A common term for tooth sensitivity is cervical sensitivity. The neck of a tooth is known as the cervical region. It is the area around the gum line where the enamel meets the underlying root of the tooth. Normally the root of a tooth is covered with a substance called cementum however cementum is a relatively soft composition and easily wears away hence exposing the dentine directly to the oral environment. When this dentine is stimulated, it causes sensitivity due to movement of the fluid within the dentinal tubules.

1. Gum recession (without gum or periodontal disease)

Gum recession causes tooth sensitivity because when the gums recede, the underlying Part of the tooth called dentine, which detects pain or sensations, becomes triggered.

This is most commonly exposed around the neck of the tooth near the gum line called the cervical region of the tooth.

 In dental terminology, we say that at the tooth dentine is exposed and the condition is called dentinal sensitivity or dentinal hypersensitivity or cervical sensitivity. All of these three terms are the same.

Causes of gum recession in the absence of gum, periodontal disease or periodontitis can be due to several factors.

These factors include the following.

• An incorrect brushing action.
• An incorrect brushing action will cause gums to recede more than what would naturally happen by wear and tear as mentioned in paragraph (f) below. There are several methods of brushing your teeth that dentists often describe and instruct. Regardless of any particular technique, it must be able to remove plaque effectively and at the same time it must reduce damage to the delicate gum tissue. Common names of techniques are the Bass, Modified bass and the Stillman technique.
• A method which many patients use and which is incorrect is the “side to side scrubbing” manner of cleaning. This is similar to when polishing shoes or when scrubbing a kitchen floor. It is basically like using a hacksaw. Scrubbing method, when used in conjunction with the other factors mentioned below i.e using a hard toothbrush, brushing too much and using an over abrasive toothpaste, will exacerbate the damage. When patients have been brushing their teeth in this way, as a dentist, I will see deep V-shaped grooves at the cervical region of the canines and premolars. In addition, the tooth wear will be worse on the left-hand side for a right-handed person and worse on the right-hand side for a left-handed person. The tooth wear has resulted in the loss of cementum and enamel causing dentine to be exposed which results in teeth being sensitive.

Fortunately, it is relatively easy to get a patient to change an incorrect action of brushing into a better action such as the Bass, Modified bass ot the Stillman technique. The dentine and enamel which has been worn away cannot be replaced but there are several ways to manage the dentine sensitivity.

Using a hard toothbrush will certainly cause the hard tooth substance at the neck of a tooth to be worn away more rapidly. It is generally the less well-known brand of toothbrushes that fall into the category. This is not to say however that you should not be using toothbrushes other than the main brand. On the contrary, there are often excellent low priced well-made toothbrushes. As a dentist, I ask every patient to bring in their toothbrush and advise them accordingly to change it if necessary.

Brushing too much is also a cause of excessive exposure of tooth dentine. If you are brushing twice a day properly, then there really is no need to brush any more frequently. Unfortunately, there is something called OCD where patients become obsessed at brushing too much. I have seen cases where patients brush 12 times a day and more.

Using an abrasive toothpaste will result in a rapid wearing away of root cementum and cervical enamel. Usually, these toothpastes are termed smokers or stain removing toothpaste by less well-known brands.

Having delicate Gums or gingivae. There are differences between the gums of different patients. Some patients have thick, tough and fibrous gingivae which are more resistant to recession than a patient who has more delicate gums.

Natural wear and tear. Gum recession occurs naturally with age but does not necessarily result in dentinal hypersensitivity because with time, a deposition of secondary dentine occurs and narrowing of dentinal tubules which reduces the pulpal response to stimuli.

2. Gum recession in the presence of gum disease or periodontal disease.

Chronic periodontal disease or periodontitis results in the destruction of the periodontal tissues which causes gum recession. The resulting hypersensitivity makes brushing painful which exacerbates the gum disease. Treatment aims to reduce inflammation and stop the further destruction of the periodontal ligament.

3. After new filling or crown.

It is normal and not surprising to experience a degree of tooth sensitivity after a new filling or after having a crown fitted. This is because fresh dentine has been cut into and these new wide tubules have been exposed to heat from the drilling, cold from the 3 in 1 syringe and bacteria in saliva. Normally, this calms down over a few days or perhaps a few weeks. If the pulp cannot recover, the sensitivity will continue resulting in permanent damage to the pulp. When sensitivity continues, it is necessary to remove the filling and crown and investigate the problem with appropriate treatment.

4. Leaking from an Old Crown or an old filling.

All filling and crowns will eventually leak resulting in a gap with access to the dentine. When this occurs, it is necessary to remove the filling and crown and replace with a new one.

5. After the placement of a new white filling or a composite filling.

It is much more common to get sensitivity immediately after you have had a white filling placed as opposed to a silver amalgam filling. There are a number of reasons why you have more chances of getting post-operative sensitivity after a composite filling in contrast to an amalgam filling. Firstly, the technique of placing a white filling is much more technically demanding and as there are various steps that need to be done particularly, so there is more room for error. When you do get consistent lingering sensitivity after you have had a white filling, first, it is usually necessary to have it removed and a temporary filling placed to allow the tooth to settle down. Once the tooth settles down, then the filling can be placed back again.

6. Dental decay or caries.

Dental decay causes damage to the tooth enamel hence exposing the underlying dentin. Of course,  if caries is untreated or undetected it will then carry on deeper into the dentine causing more pain and more sensitivity. By the time the Decay has gone into most of the dentine and is close to the Pulp, the sensitivity will be unbearable. The remedy here is to treat the decay.

7. After scale and polishing or a course of gum treatment.

Many patients complain that their teeth have become too sensitive after they have had a course of gum treatment or they have had their teeth scaled and polished.  Usually, this is only temporary and it disappears within a short period such as a few days or even a couple of weeks. Scaling especially root planing removes tartar from the root surface to where it is attached and that’s why post-operative sensitivity occurs as dentinal tubules are now exposed to the oral environment.

8. After a tooth whitening treatment.

 Teeth can become very sensitive after a course of tooth whitening treatment. Overall, an intensive course of tooth whitening carried out at the dental surgery will have more sensitivity than a treatment that is carried out at home using tooth whitening trays. It is the dentine that acts in response to the hydrogen peroxide.  The sensitivity is usually temporary and disappears after 1 or 2 days.

9. Tooth wear.

 Tooth wear consists of wearing away of enamel and dentine. When the enamel has worn away and the dentine becomes exposed, due to abrasion attrition or erosion, this will cause sensitivity.

The treatment of tooth sensitivity.

 Treatment for tooth sensitivity can be divided into 3 main phases.

1.  The first phases to try to remove the cause of the sensitivity.
2.  The second phase is to try to alleviate the symptoms of sensitivity.
3.  The third phase is to prevent further sensitivity from reoccurring.

The first phase is where we try to remove the cause of sensitivity. This could be instructing the patient in a correct tooth brushing technique or by asking the patient to eat less foods that are causing erosion of the enamel. Each case is individual depending on the cause. Often, the cause is multifactorial.

The second phase is to try to alleviate the symptoms of sensitivity. This can be done at home and it can also be done in the surgery.  Treatment at home usually consists of using a sensitive type of toothpaste. For more effective and rapid relief, the toothpaste can be applied or dabbed directly onto the tooth and left without rinsing.

Treatments carried out at the surgery include using varnishes which block and deposit chemicals inside the dentinal tubules and reducing that sensitivity. Where the dentine defect is deep, glass ionomer cement or glass ionomer Restorations are extremely effective at reducing sensitivity.

The third phase is to prevent further sensitivity from reoccurring. This is done by making sure that all the causes of sensitivity have been removed and any treatment that has been instigated, goes into a maintenance phase. That maintenance phase could be for example to continue using a sensitive toothpaste on the regular basis.