What Causes Sensitive Teeth After Filling?

Have you just got a tooth cavity filled recently and noticed that your teeth have become sensitive to heat and cold? Here are the causes, and what you can do...
Cavities damage the internal structure of teeth. So filling them is necessary to prevent tooth loss. Cavity filling procedure involves, first of all, removing the decayed portions of the tooth, and then filling the holes so that bacteria cannot enter, and cause further decay. There are various types of fillings such as gold, silver amalgam, composite resins, and porcelain fillings which are used, depending upon a number of factors such as the extent of repair needed, the allergies a person may have towards certain metals, and also the cavity filling cost involved. The cavity filling procedure may cause toothache and sensitivity for a period of a few weeks. In case it persists, it may be due to one of the following reasons, and needs to be checked out by the dentist, at the earliest..
Persistent Problems in the Internal Parts of the Tooth
A tooth has four parts namely dentin, pulp, enamel, and cementum. The dentin is permeable and extends on all sides of the pulp. If the tooth decay is closer to the dental pulp, some bacteria could be present in the dentin. Because of the porous nature of the dentin, the bacteria may spread from the dentin to the filling and the tooth. This bacteria causes tooth infection, which leads to sensitivity. A detailed dental examination is needed in this case, as the teeth may require further treatment like a root canal. An inflamed dental pulp is another reason for sensitivity. Dental pulp is a component of the tooth, made up of living soft tissue and certain other cells. Sometimes a cavity may cause inflammation of the pulp. In general practice, any inflammation or pain has to be completely eradicated before any tooth treatment. But sometimes this is overlooked. Thus, this inflammation may not go away even after the cavity filling procedure. This leads to deterioration of the teeth from the inside, and thus, causes sensitive teeth after cavity filling.
Irritation Due to Filling Action
Sensitive teeth after cavity filling could actually be influenced by the size of the cavity filled. If the size of the cavity is big, it means that the cavity is close to the nerves. The corresponding filling will be big too and may irritate the nerves further, thus causing sensitivity. Usually a tooth filling is necessary due to tooth decay. When a filling is done, the already sensitive tooth is acted upon again, and gets further irritated, resulting in tooth pain. The tooth does get better on its own, though it may take several days. Thus, having a sensitive tooth after filling is quite normal. You may ask your dentist to put some medicated filling in order to prevent sensitivity and toothache. Or alternately you may use certain home remedies for toothache pain relief like applying peppermint oil, ice packs or ginger pulp over the affected area.
Badly Molded Fillings
During a teeth decay filling, the dentist usually asks the patient to show him his biting action by clenching the two jaws together. This done so that the dentist is able to fill the tooth in a manner that the jaws can be closed properly after the completion of the filling procedure. But a patient's mouth is numb when the fillings are being done due to the use of anesthesia. So he may not be able to bite correctly. Thus, correct filling shape and fitting might not be achieved. This is one of the major sensitive teeth causes. A simple bite adjustment procedure can be done to avoid sensitive teeth after a filling.
Sensitivity to Certain Filling Components
Sometimes if a metal is used for filling a very damaged dental cavity, it may lead to sensitive teeth, as metallic fillings can channelize hot and cold sensations to the tooth center. This usually lasts for a maximum of 2 months. If it lasts beyond that, consult a dentist as there could be some other cause of your sensitive tooth after filling. Teeth with silver fillings may develop some internal cracks. These cracks which are very difficult to discover may irritate a nerve. In this case, the entire filling has to be removed and a new filling has to be done.
Improper Techniques Adopted for Fillings
White composite filling is generally done on the lingual (inner) surface of the teeth. If the dentist is not properly trained in the technique for this kind of filling, it causes sensitive teeth. Take a second opinion from a trained cosmetic dentist, as a general dentist may not be well-trained in this field, and thus, create circumstances for sensitive teeth. Sensitivity may also be the result of bonding failure. Bonding is a technique of using composite resin filling to cover teeth flaws such as teeth stains, crooked teeth, or cavities. Sometimes, these composite fillings may cause acute pain to the patient, especially when food is chewed. Contamination of bonding substances or bonding technique failure by the dentist are the major causes for teeth sensitivity. In order to fill cavities, the teeth is prepared first in order to remove active decay. Tooth preparation involves using either of these procedures - drilling of the tooth, laser treatment, or air-abrasion. All these processes can sometimes cause sensitivity.
There are numerous reasons for having sensitive teeth after a filling. A proper dental care routine is necessary to maintain dental health and to avoid cavities in future. As far as the cavities you already have are concerned, it is normal to develop some minor sensitivity after a filling, but if it does not go away in a few days, a proper dental examination is recommended.