There was a time when a person with a small cavity in a tooth with an existing filling would need the complete removal of both the cavity and filling to treat the tooth. In fact, this was considered the “standard of care” for dental treatment. The dilemma is that this type of treatment is sometimes unnecessary, and could place the tooth at an increased risk for further dental problems in the future. To better understand when a tooth should be treated more conservatively (only removing the cavity, not the existing filling) we need to know a little bit more about the different parts of the tooth.
Dentists use a type of shorthand when describing teeth. Teeth are identified by numbers, 1-32, and the parts or surfaces of the teeth by letters, B,D,I,L,M, and O. For example, “M” mesial, or “D” distal, is the front or back part of the tooth, respectively. An “O” occlusal, is the top or biting surface of a back tooth (molar or premolar), and an “I” incisal, is the biting edge of front teeth (incisors and canines). A “B” buccal, is the part of the tooth towards the cheek, and an “L” lingual, is the part of the tooth towards the tongue. So if the dentist says number 3, M-O-D, you’ll know that your molar has a cavity involving the front, top, and back parts of the tooth.
Cavities can appear on any part of the tooth, and often occur in close proximity to an existing filling. One common place for this to happen is on the top or biting surface of a molar. Often the cavity can be removed and repaired while leaving the existing filling partly or completely intact. The benefits of this type of conservative treatment can be substantial. From the patient’s perspective, there is less drilling, which can translate into less potential discomfort during and after the procedure. Another benefit of leaving the existing filling intact is that less healthy tooth will need to be removed. This can have the benefit of keeping the tooth more structurally strong, which may make it less susceptible to damage in the future, avoiding more extensive dental treatment.
Unfortunately, in many cases, the existing filling must be removed during treatment of a cavity. This decision is made on an individual basis, with the discretion of your dentist. Even so, conservative treatment of cavities is becoming the new “standard of care”, and may prevent the need for more extensive dental treatment in the future.