Persistent tooth pain after filling

A persistent tooth pain after having a dental filling should be considered as a sign of possible complications. Although a mild sensitivity after a filling is normal, if you experience a continued or/and intense pain you must visit your dentist for examination of the possible causes.

There are several conditions that may cause persistent tooth pain after filling that will eventually need the intervention of the dentist to resolve the problem. These include:

Bonding failure of the dental filling

When the tooth surface where the filling material will be added is not etched and dried properly, or becomes contaminated with saliva or water, there is increased case of bonding failure. In this case the filling will not be bonded properly to the tooth tissue. Even a hair-like gap between them can allow the external stimulations to reach the pulp and cause a toothache. Except of causing tooth pain, bonding failure increases the risk of new decay and if the gap is deep it can provide a gate for bacteria to enter the pulp and infect it. The symptoms of bonding failure resemble to those of a cracked tooth.

This type of tooth pain after filling is a complication more common with composite tooth-colored fillings that require a more complicated technique for their placement than traditional silver amalgam fillings.

Fillings not shaped/smoothed properly

If the edges of the dental filling are not shaped properly or they are purely smoothed, the adjacent teeth or gums may become irritated and cause a tooth pain after filling.

The inter-proximal areas between the filling material and the adjacent tooth is the usual suspect for this kind of problems. A filling that is larger than expected, coming in contact and pressing on the tooth next to it, will not only cause a toothache but will also increase the risk of additional caries in both teeth because the area will be difficult to clean.

Sharp edges of the filling material that are not polished properly, especially in the gum margin area where the tooth crown meets the gums, can cause gums irritation and severe discomfort.

Incorrect bite

A common but easy to correct cause of tooth pain after filling is the incorrect bite, when either the filling is made higher than the original tooth or one or more of the cusps are not shaped properly. In this case when you bite down the biting force is not exercised evenly among all teeth, but most of it is exercised on the filled tooth or one of its cusps. The excessive force causes an intense tooth pain when chewing.

The dentist must shape carefully the upper biting surface of the restored tooth so that it comes in perfect contact with the opposite tooth of the other jaw, to avoid having problems of malocclusion that can cause toothache after the filling.

Galvanism effect

Oral galvanism is a condition when two different metals in the mouth come in contact, such as an existing silver crown and a new amalgam filling, creates an electrical charge that causes tooth pain similar to that of sensitive teeth. Usually the condition resolves in its own after some time, but if it continues it is possible that one of the restorations must be replaced using another material.

Damaged pulp during the filling procedure

While some irritation of the pulp tissues can be expected during a dental filling procedure, sometimes the pulp is severely damaged. The risk is higher as closer to the pulp has reached the tooth decay or other damage that made necessary the tooth restoration. Excessive use of a high speed drill close to the pulp or inadequate water spray cooling can cause the temperature inside the pulp to rise into critical levels. If the remaining dentin layer between the pulp and the area that is being prepared for the filling is less than 1.5mm, the pulp may get damaged even if the dentist takes the necessary precautions.

Severe tooth pain after filling will also occur if the dentist accidentally drills into the pulp chamber without noticing it. In both cases the tooth will most likely need a root canal therapy to stop the toothache.

Infected pulp tissue

A common cause of persistent toothache after filling is that tooth decay bacteria may have reached the pulp chamber and infected it. This could happen if the dentist does not remove successfully all the decayed tissue before filling the tooth allowing the decay to continue to destroy the tooth under the filling. The toothache is usually constant, especially when eating.

Another possibility is that the decay was too close to the pulp and some bacteria had already managed to reach the pulp through the porous dentine but had not given symptoms of tooth infection until the tooth was filled. Whatever the cause of the tooth infection, a root canal is necessary to save the tooth and relieve the pain.

Post root canal pain

If the filling is used to restore the tooth after a root canal therapy, it is more likely to experience a toothache after filling. Although in most cases the tooth pain is caused by the irritation of the periodontal tissues around the apex of the tooth roots and will subside in a few weeks, a persistent intense pain may indicate a root canal failure. Post root canal pain usually appears as a referred pain coming from another tooth adjacent to the treated one.

Allergic reaction

A rare complication of a filling procedure is the development of an allergic reaction to the silver amalgam used in the filling. Other common allergy symptoms as itching or rash may also be present along with the toothache after filling the tooth. Replacing the silver filling with a composite filling will resolve the condition.