An indirect pulp cap procedure is used when bacterial decay has reached near to the pulpal chamber, causing inflammation and threatening the survival of the tooth. Since maintaining pulpal health is paramount when saving a tooth, your dentist may use a pulp cap to kill bacteria in the area, and stimulate the tooth to lay down more dentin just above the pulpal chamber. There are two types of pulpal caps available. An indirect cap, which is used in treating a tooth without any exposed pulp tissue, and a direct cap, which is used when the pulp has already been exposed. This dental code desceription refers to an indirect pulp cap.
Similar to a sedative filling, an indirect pulp cap is used when a deep cavity is present. It differs however, in the type of therapeutic compounds used, and because, on occasion, a portion of the decay near the pulp may be left in place to be removed at a later date, or left in place indefinitely.
As mentioned previously, when damage extends deep within the tooth, the most critical step a dentist can make to avoid tooth loss is to protect the pulp from the encroaching bacteria of a cavity. The dentist employs the most unlikely of partners in this battle – the tooth itself. Recognizing the threat to its own survival, the tooth reacts by having cells along the pulpal wall begin laying down fresh dentin to keep bacteria at bay. In doing so, the size of the pulpal chamber is decreased from the top down, as a new layer of dentin is created. This provides your dentist with a safe barrier from which to eliminate the encroaching decay. Think of it as if the tooth were placing a shield between its valuable pulp and the bacteria that want to destroy it, and continually making that shield thicker and thicker as the bacteria got nearer.
In order for these cells to get ahead of the damage occurring just above the pulp, however, they need the assistance of the dentist to remove the bacteria burrowing downward. This is the precise reason why a pulp cap is often employed. By excavating decay from the tooth and properly medicating the tooth with a filling that protects the pulp, these cells (called odontoblasts), can work at laying down this additional layer of dentin without fear of penetration from bacterial decay.
Unlike traditional amalgam or composite resin fillings made of metal or acrylic, such fillings are made first by layering a coating of calcium hydroxide at the deepest point of decay just above the pulpal chamber, and then often filling above that with a mix of oil of clove (eugenol) and zinc oxide. The natural properties of these two materials allow them to effectively “sedate” the tooth, (or, allow it to calm down) and work together with the calcium hydroxide to allow the tooth to heal itself.
While historically a two-step procedure, indirect pulp caps have matured into a single visit event where dentists allow a fraction of decay to remain since research suggests the alkalinity of calcium hydroxide's kills off this fraction of remaining bacteria. Doing so also ensures there is no accidental entry into the pulpal chamber with dental tools. Some dentists may still perform this procedure in two steps, with the second being to remove the temporary filling, excavate any remaining decay, and then to re-fill it once the dentist is assured of the tooth's overall health.
In cases when this is a two-step procedure, the filling is commonly left within a tooth for at least one month, sometimes three. Regardless of the allotment of time needed, once sufficient, your dentist will be looking for signs the tooth is experiencing less, or no, inflammation, and has begun laying down an additional layer of dentin. If these conditions are favorable, and you are asymptomatic, a root canal may be averted, and instead, a crown might be placed on the tooth. If, on the other hand, the pulp is determined to be too badly damaged, and not “live” or “vital,” root canal treatment, or extraction might be necessary.