There are two types of pulp caps, indirect and direct. An indirect pulp cap is a procedure that Dr. McArdle performs for you before placing a direct restoration (filling) after his removal of decay from one of your teeth leaves its nerve chamber precariously close to the surface. A direct pulp cap is performed before placing a filling when the nerve chamber of your tooth is in fact encroached upon by the process of decay removal (an event indicated by bleeding from the nerve chamber). Dr. McArdle does not perform direct pulp caps because in his experience the long term chances for survival of nerves so breached are poor. Under these circumstances, Dr. McArdle will place a medicated temporary filling material in your tooth to calm the injured nerve and shield it until it can either be removed by the endodontist (root canal specialist) as part of root canal therapy or you have the tooth removed, at your discretion.
Your tooth is ordinarily organized into three layers with the outermost layer being either enamel (normally found above the gum line) or cementum (the outer coating of your tooth's root). The middle layer is a substance called dentin and the inner core of your tooth is a compartment containing its nerve (along with blood vessels and connective tissue) called the pulp chamber. The terms pulp and nerve are synonymous when speaking of your teeth. When decay penetrates through the enamel of your tooth into dentin, it will progress (at varying rates) toward the pulp. This is because dentin is much less mineralized (and so softer) than enamel and decay will traverse dentin much more certainly and rapidly than it will enamel. For this reason any decay that has involved the dentin of one of your teeth must be removed and the tooth structure that is lost in the process must be replaced with some type of dental restorative (such as a filling, an inlay/onlay or a crown).
If your tooth is decayed extensively, removing the decay may leave its nerve covered by only a scant layer of dentin. In this situation (usually when less than one millimeter of dentin is left covering it) your nerve is referred to as a "blushing pulp" and it indeed may be visibly discernable through the dentin with the naked eye. In this instance, very discreet elimination of the last traces of decay is crucial to the pulp's survival as is the use of special restorative materials to insulate the nerve against irritation and strengthen the remaining veneer of dentin. This is what an indirect pulp cap is. Dr. McArdle uses an adhesive liner under a base of unique low-viscosity bonding material to achieve the required insulation and has written about his technique in the dental journals. A definitive dental restoration can then be placed to seal your tooth and restore it to function.
The deepest part of a cavity preparation post decay removal. The reddish area is the visible nerve,
but the absence of bleeding indicates it has not been breached.
Pulp caps do not always succeed in sparing your tooth's nerve as the pulpal irritation generated during excavation of decay may inflame the nerve beyond its capacity to heal. However, it has been Dr. McArdle's experience that when pulp caps are skillfully accomplished, they succeed more often than not. If the pulp cap cannot allow the nerve in your tooth to heal, it will eventually succumb to the irritation and then it can become abscessed (infected) which may cause you to have an old-fashioned toothache. At this point you will need to decide whether your expired pulp will be removed endodontically (through root canal treatment) or by extraction. These are the only two ways in which a diseased nerve can be disposed of.
The same preparation after the extra pulp cap material has been placed. The additional insulator now covers the "blushing" pulp.
You should be aware that most dental benefit plans will not cover a pulp cap when it is completed at the same visit in which your tooth is definitively restored. They require that a provisional restoration be placed over your pulp cap at this visit and that your tooth be definitively restored later at a separate visit. Dr. McArdle disagrees with this policy as he believes that the nerve in your tooth, which has already been aggravated by the initial eradication of decay, should not be further agitated by a second (and ultimately unnecessary) procedure. Dr. McArdle also believes that you should not be forced to incur the added expense and inconvenience that this piecemeal approach entails.
The same tooth with its definitive restoration over the pulp cap now in place.
IF YOU HAVE ANY QUESTIONS ABOUT ANY ASPECT OF PULP CAPPING, PLEASE ASK DR. MCARDLE!