MANY ARTICLES about the success and failure of endodontically treated teeth are concerned about the occlusal seal. The current thinking is that many endodontic failures are due to coronal leakage. One of the reasons that I pursued one-visit root canal treatment was to eliminate interappointment leakage of the temporary filling (Cavit) and there-by to eliminate iatrogenic infections. One-visit treatment of all teeth has been very successful with regard to this issue. It has been a long time since we have seen an iatrogenic infection in the office.
However, several patients per year fail to return to their general dentist in a timely fashion. They seem to get lost for six months to a year. This is a very long time for a temporary filling to hold back the ravages of the oral environment. Once the temporary starts to leak, the tooth gets infected in a short time (within several weeks). With this in mind, we have used the following materials as temporaries:
1-Cavit Easy to use but will dissolve out in some mouths within two weeks.
2-Temrex and IRM Both ZOE based materials—stronger than Cavit and will last longer—a month or two. We mix them thick—to the consistency of Cavit.
3-Durelon (Polycarboxalate) Better, but still hard to mix.
4-Zinc Phosphate cement Very hard, can last up to six months, works well in the access of PFM crowns, hard to mix thick, quick working time.
5-Glass Ionomer Very hard, lasts several months, releases fluoride, weak bond to tooth structure, seals well, hard to mix, long setting time.
As with most aspects of dentistry nothing is perfect. I was looking for a cement that would not wash out, was easy to use, and was wear-resistant enough to last close to a year. It was in front of my nose all along. I now use the dual cure Ti-Core® to seal the occlusal access opening. It comes in tooth color and a new stark white shade to be released early in October. The white gives you great contrast to the root’s yellow color for easy preparation in the posterior region and yet maintains the esthetics of any future restoration. Certainly, there is no doubt about strength. It is a hybrid Bis-GMA composite and will last many years as an access restoration.
Lastly, you can create a great seal. You can either place a bonding agent first or just etch the dentin. Since it is a non-vital tooth, we are not worried about sensitivity. Therefore, generally I just etch all the dentin with 37 percent phosphoric acid for 20 seconds. This will open up the tubules and intratubular dentin and allow bonding to occur. This creates a great strong seal. No iatrogenic infections here, even if the patient forgets about getting the permanent restoration for several months.
by : dr.Allan Deutsch