Q. Could you define perforations and describe their etiology?
A. Perforations represent pathologic or iatrogenic communications between the root canal space and the attachment apparatus. The causes of perforations are resorptive defects, caries, or iatrogenic events that occur during and after endodontic treatment. Regardless of etiology, a perforation is an invasion into the supporting structures that initially incites inflammation and loss of attachment and ultimately may compromise the prognosis of the tooth.

Q. What are the factors influencing perforation repair?
When evaluating a perforated tooth, there are a number of factors that must be considered individually and collectively to properly guide treatment. Treating clinicians must identify the four dimensions of a perforation and understand how each of these entities critically affects treatment selection and prognosis.

1) Level: Perforations occur in the coronal, middle and apical one-thirds of roots. More coronally positioned perforations threaten the sulcular attachment and pose different treatment challenges than more apically occurring perforations. In general, the more apical the perforation, the more favorable the prognosis.

2) Location: Perforations occur circumferentially on the buccal, lingual, mesial and distal aspects of roots. The location of the perforation is not so important when nonsurgical treatment is selected but its position is critical if a surgical repair is considered.

3) Size: The size of a perforation greatly affects the clinician's ability to establish a hermetic seal. The area of a circular shaped perforation can be mathematically described as "pi.r.squared". Therefore, doubling the perforation size with any bur or instrument increases the surface area to seal by four-fold. Compounding the challenge to efficiently seal a perforation is that many of these defects are ovoid in shape due to their nature of occurrence.

4) Time: Regardless of etiology, a perforation should be repaired as soon as possible to discourage further loss of attachment and prevent sulcular breakdown. Chronic perforations exhibiting a loss of sulcular attachment pose treatment challenges that potentially escalate to surgical correction and efforts directed towards guided tissue regeneration procedures.

Q. What are the best materials available for repairing perforations?
A. In general, ProRoot (Dentsply Tulsa Dental) is the restorative material of choice to repair virtually all perforation defects. The original ProRoot was only available as a grayish-colored material which may have precluded its use when there was an esthetic consideration. Fortunately, however, ProRoot has recently become available in a tooth-colored material as well. Other tooth-colored restoratives, such as a dual cured composite, require the placement of a barrier so the material is not contaminated by moisture during use. A barrier serves as a "hemostatic" and a "backstop" so a restorative material can be placed into a clean, dry preparation with control. Calcium sulfate is the barrier of choice when using the principles of wet bonding, is biocompatible, osteogenic, resorbable, and following placement, sets brick-hard. When set, calcium sulfate is trimmed back to the cavo surface of the root. A dual cured, tooth-colored restorative can now be placed against the barrier and utilized to seal a root defect.

Q. I perforated a canal while I was preparing it for root canal obturation. What would you do in this case?
A. In general, when a tooth is perforated, the defect should be repaired as quickly as possible to protect the periodontal attachment. From your question, I could not tell if you are dealing with an apical or midroot strip perforation. Depending on where the perforation is will determine treatment sequence. However, the material of choice to repair and seal a perforation is Mineral Trioxide Aggregate (MTA), commercially known as ProRoot. For further information regarding the mixing, delivery and placement of ProRoot, see the FAQ section of this site entitled Transportations. In addition, I also refer you to my Ruddle on Retreatment DVD "Management of: Blocks, Ledges, Transportations & Perforations " to explain the precise clinical technique necessary for repairing perforations.

Q. What are the most popular pulp cap materials?
A. ProRoot. This material has virtually replaced all other pulp capping agents.