Cavities in baby teeth progress faster and affect the nerve sooner than in permanent teeth. Long before a cavity becomes visible in a baby molar, it grows inside the dentin before the overlying enamel collapses and reveals a “hole” in the tooth. The true extent of the cavity at this stage is usually three times as large as what it appears to be from the outside.
What is a pulpotomy?
A pulpotomy (partial amputation of a nerve) is the procedure of choice for treating large cavities in baby molars that have invaded the nerve. At this stage, the nerve (pulp) is still alive, there is little or no pus, frequently no pain, but bacterial invasion has occurred and it is only a matter of time before an abscess forms and the tooth must be prematurely extracted.
Why bother to treat baby teeth if they are to be replaced?
We want to keep primary molars for as long as possible to maintain not only space for the incoming teeth, but vertical bite support as well. These two factors are essential in proper orthopedic and orthodontic development of the teeth and jaws. Most parents underestimate the time that these molars will persist in their child’s mouth. Primary molars are replaced between the ages of 11 and 13, long after the incisors are replaced. If a large cavity appears at age 4, for example, that tooth will have to be preserved for at least another 7 years. If that cavity is ignored for such a long period, it will certainly cause an abscess and tooth loss within a year.
How does a pulpotomy differ from a root canal?
In a pulpotomy procedure, the part of the nerve within the canals inside the actual roots is preserved, while the tissue in the pulp chamber within the top part of the tooth is amputated. Due to the large blood supply within baby teeth, the remaining tissue in the canals is kept alive. In a root canal procedure, however, which is usually performed on adult teeth, the complete nerve and pulp are removed, resulting in a dead tooth.
What materials are used in a traditional pulpotomy?
After the decay is removed and the pulp chamber is amputated by drilling the nerve tissue away with a bur, the opening to the nerve canals is treated with formocresol for a few minutes, in order to create a fixed, dead and sterile layer as a barrier between the top chamber and the live canal tissues. A clove-oil based cement is used to fill the void chamber. The tooth is then restored with a stainless steel crown which is adapted to fit around the tooth to serve as a protective cover. In the past decade, many authors have debated the formocresol technique due to the material’s highly toxic and mutagenic (cancer-producing) nature.
What is a laser/MTA pulpotomy?
We use an electric drill to remove the top part of the decayed tooth. We then use the Waterlase to remove the pulp. Because there is no physical contact and mechanical trauma, coupled with the natural sterilizing effect of the laser, the chances of the remaining nerve staying alive is much greater. After gently rinsing with hydrogen peroxide, we seal the exposed nerve with MTA, that acts as an inert and sterile barrier between the live nerve and the top part of the restoration. We use a glass ionomer cement to cover the MTA, and after it sets, we restore the tooth with a bonded composite resin. If bonded correctly, this will last the few years before the tooth is shed.
What is the success rate of laser/MTA pulpotomy and how does it compare to traditional pulpotomies?
More than ten years of this procedure in our office have resulted in a much lower failure rate (5%) than traditional pulpotomies (10-20%). The scientific literature confirms the efficacy of MTA being the most biocompatible of materials, showing the least in-vitro toxicity compared to other cements (1), and superior in success rate than formocresol (2, 5). In fact, MTA has been shown to be superior in forming a desired “dentine bridge” over the underlying live nerve compared to other materials such as the highly toxic formocresol (3), which reportedly causes half of the nerve to die within the canal space. A summary of many studies in another publication also outlines the efficacy and success rate of MTA vs Formocresol (4). Lasers have become increasingly popular in soft and hard tissue procedures and naturally pulpotomies are excellent candidates for laser use (6).
The Procedure in Pictures
In a group of images Dr. Sarkissian demonstrates how a pulpotomy is performed on a child’s primary molar. (Warning: There is a bit of blood visible in those images.)
- J Clin Pediatr Dent. 2009;33(3):217-21
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- LASERS IN MEDICAL SCIENCE Volume 23, Number 4, 443-450, DOI: 10.1007/s10103-007-0505-3