INTRODUCTION
Success Versus Survival
Endodontic therapy under modern treatment protocols has been shown to have long-term clinical success rates in the range of 81% to 97%.1,2 The “success” rates can go to either extreme of that range depending on whether we are evaluating healed versus nonhealed under the strict guidelines that the endodontic literature holds for success. Or, is the tooth being held to the looser evaluation criteria set forth when discussing “survival”? Even with the high clinical success rate of initial endodontic treatment, it’s obvious to see this leaves clinicians with a 19% incidence (on the very high side) of encountering post-treatment disease in our patient population.
Post-Treatment Disease
No matter what criteria we use, it becomes obvious when we evaluate the prognostic indicators in the literature that some of these “failures” could have been avoided with proper restorative treatment. One large study in particular found a 97% survival rate for initial endodontic therapy.2 When some of the prognostic indicators are evaluated, such as a good coronal restoration, we can see that a large number of these failures can be attributed to an inadequate coronal seal. Of the 3% of failures in this particular study, 85% of the teeth presenting with post-treatment disease had no full coronal coverage. Other common causes of post-treatment disease can also be iatrogenic in origin, while others are related to more complicated microbiological and host response factors including persistent or reintroduced intraradicular micro-organisms, extraradicular infection, foreign body reaction, and true cysts.3 There are a multitude of reasons for any of the above clinical situations to arise.
Advanced Imaging Aids Treatment Planning
As clinicians, the questions that are left for us to answer through radiographic imaging and clinical testing are (1) what is the etiology, and (2) what is the prognosis of any suggested treatment? There have been countless articles in the literature that have shown no correlation between clinical and radiographic testing and histological findings.4 Some authors, though, have suggested the potential to correlate 3-D imaging with histological findings.5 For many years, 2-D radiographs have aided in diagnosis of dental disease, with the first dental radiograph claiming to have been taken in 1896. However, as with all technology, there are limitations. When reviewing cases for nonsurgical retreatment, surgical retreatment (apicoectomy), or extraction, I prefer to piece the puzzle together using all the potential diagnostic information available. I routinely take a narrow-field CBCT image of any teeth exhibiting post-treatment disease with an uncertain etiology.
This article will present 2 cases that were retreated with the aid of CBCT imaging (CS 9000 [Carestream Dental]), along with appropriate CBCT followup scans. In my office, all cases are treated using enhanced magnification and illumination with a surgical operating microscope (Global Surgical).
CASE REPORTS
Case 1
A 31-year-old male presented to the office on referral from his general dentist for evaluation of a periapical radiolucency related to the maxillary left first molar, tooth No. 14. Upon initial evaluation, appropriate radiographs were taken (Figure 1). Clinical testing was preformed and the recommendation was made to take a narrow-field CBCT image of tooth No. 14 to gain better insight into the etiology of the presenting post-treatment disease (Figures 2 and 3). The axial view (Figure 2) reveals an untreated mesial buccal-2 (MB2) canal on No. 14 with the sagittal view (Figure 3) revealing apical periodontitis related to the MB, distal buccal (DB), and palatal (P) roots of No. 14 as well. The sagittal view also shows a short fill related to the MB, DB, and P roots, meaning the entire canal space may not have been properly shaped and cleaned. With the CBCT imaging, we now have a better understanding of why No. 14 is presenting with post-treatment disease. This information is extremely important whenever we plan to discuss etiology and prognosis with our patients. Based upon current nonsurgical retreatment literature, we can expect a success rate for our proposed treatment plan of approximately 86.5%,6 assuming that the patient follows up and has a final restoration placed in a timely manner.
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At the patient’s next appointment, the nonsurgical retreatment of tooth No. 14 was begun. After proper anesthesia and rubber dam isolation, access was gained using a surgical operating microscope (Global Surgical). Conservative access was gained through the occlusal of tooth No. 14. Upon access, it was noted that the MB, DB, and P canals were obturated with Thermafil plastic carriers (Dentsply Sirona). The untreated MB2 canal was located with the aid of the operating microscope along with an ultrasonic unit (Satelec) and treated. The Thermafil carriers were removed from the other canals with the aid of irrigants, Hedstrom files, and ultrasonic instruments (Figures 4 and 5). All 4 canals were treated with a calcium hydroxide paste for 10 days. At the patient’s next visit, No. 14 remained asymptomatic. After proper irrigation and additional cleaning and shaping, the tooth was obturated and a temporary Cavit (3M) seal was placed (Figure 6). It is important to remind our patients that endodontic therapy is not complete until they have had a permanent restoration (ensuring coronal seal) placed by their referring dentist. Generally speaking, I do not routinely take a CBCT followup until after the patient’s one-year recall. For this particular case, I was eager to see the patient for a 6-month recall to observe the extent of healing that can be achieved after a shorter recall period. With the use of a narrowfield CBCT (CS 9000) unit, the effective dose for the patient when imaging a maxillary posterior tooth is not significantly different than taking a conventional periapical (PA) radiograph for their follow-up exam. In my opinion, this, coupled with that fact that the CBCT imaging can give us better insight into the patient’s healing, warrants CBCT imaging for follow-up when the patient initially presented with a large PA radiolucency. The patient was unable to make a 6-month recall but reported after 9 months for the follow-up CBCT image (Figures 7 and 8). The sagittal view shows almost complete bony healing of the previous PA lesion related to tooth No. 14 in only 9 months; and the axial view now shows an obturated MB2 canal as well. We can only assume to expect complete bony healing in the following months based on the current progress of the case. A well-fabricated final restoration by the patient’s general dentist (Figure 9) aids in the pronounced healing that we see. The patient will be followed for regular recall examination at my office.
Case 2
A 50-year-old male presented to the office complaining of pain and swelling in the upper left posterior quadrant. His general dentist had referred him for evaluation of his maxillary left first and second molars, teeth Nos. 14 and 15 (Figure 10). After clinical evaluation and testing, it was noted that there was an intraoral P swelling between Nos. 14 and 15. Testing revealed a necrotic pulp diagnosis for No. 14, and No. 15 had been previously treated endodontically. The periradicular diagnosis of acute apical abscess needed to be further investigated with 3D imaging (CS 9000) (Figures 11 and 12). After evaluation of the CBCT scan, it was clear to see that the acute apical abscess was related to the P root of tooth No. 14 and that there was a less than ideal initial endodontic treatment of No. 15.
After the proper periradicular diagnosis was made for both teeth in question, the decision was made to nonsurgically retreat tooth No. 15—as the etiology was clear, thanks to the advanced imaging that was provided by the CBCT unit—and to provide initial treatment for No. 14. At the same appointment, No. 15 was accessed; the MB root presented with gutta-percha and was retreated. The untreated DB and P roots were located and treated, and then all canals were medicated with calcium hydroxide paste (Figure 13). At this point, No. 14 was accessed (Figure 14), and after careful review of the CBCT image, all 4 canals were located. After both teeth were medicated with calcium hydroxide for 10 days, the patient returned for his obturation visit. Upon clinical exam, the P swelling had resolved and the patient was symptom-free. Obturation was completed and conventional post-op radiographs were taken (Figure 15); the MB2 being seen on the completion film for Nos. 14 and 15. The patient presented for a 22-month recall, and at this appointment, a follow-up CBCT image centered on Nos. 14 and 15 was obtained (Figures 16 and 17). Again, the full bony healing of the lesion can be seen. From the recall radiograph (Figure 18), one can also see that the patient received an excellent coronal seal from his general dentist, vital to the long-term success of this case.
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DISCUSSION
After proper diagnosis and testing, aided with CBCT imaging, treatment plans for these patients were decided upon with input from each patient’s general dentist. In the author’s opinion, the treatment plans chosen were minimally invasive and cost effective in both cases presented. The patients will be evaluated with annual recall visits in the endodontic office to evaluate their long-term success. Both patients received informed consent prior to treatment, explaining that, due to the size of the lesions, an additional procedure of apical surgery may be needed. All patients should receive a proper informed consent prior to finalizing the suggested treatment plan. Judging by the complete healing attained at 9 months for case 1, and at 22 months for case 2, any additional procedures will likely not be needed to maintain the teeth in question.
CLOSING COMMENTS
Endodontic therapy for a diseased tooth, whether it be initial treatment or nonsurgical retreatment, is the best option that we have to save the natural dentition. Some important components to success include consistently taking a team approach when devising the patient’s treatment plan. Another important step is to always assure that the patient is well informed and understands all aspects of the treatment plan. The patient should know in advance of the treatment what steps will come next after the endodontic therapy is complete, such as the need for a final coronal restoration. When this approach is taken it greatly increases our chance for longterm endodontic success.
References
- Friedman S, Abitbol S, Lawrence HP. Treatment outcome in endodontics: the Toronto Study. Phase 1: initial treatment. J Endod. 2003;29:787793.
- Salehrabi R, Rotstein I. Endodontic treatment outcomes in a large patient population in the USA: an epidemiological study. J Endod. 2004;30:846850.
- Nair PN. On the causes of persistent apical periodontitis: a review. Int Endod J. 2006;39:249281.
- Seltzer S, Bender IB, Ziontz M. The dynamics of pulp inflammation: correlations between diagnostic data and actual histologic findings in the pulp. Oral Surg Oral Med Oral Pathol. 1963;16:969977.
- Aggarwal V, Logani A, Shah N. The evaluation of computed tomography scans and ultrasounds in the differential diagnosis of periapical lesions. J Endod. 2008;34:13121315.
- Gorni FG, Gagliani MM. The outcome of endodontic retreatment: a 2-yr follow-up. J Endod. 2004;30:14.
Dr. McCormack received his DDS from Stony Brook (NY) School of Dental Medicine. After completion of a general practice residency at Northport Veterans Affairs Medical Center, he went on to complete his endodontic training at Stony Brook School of Dental Medicine. He currently works full time in his private practice in Stony Brook. He is involved in research related to dental trauma, nonsurgical endodontic retreatment, and 3-D imaging. He teaches as an attending endodontist at St. Charles Hospital, general practice residency, as well as in the postdoctoral endodontic program at Stony Brook University. He lectures on current endodontic treatment protocols. He can be reached at (631) 7511400 or via email at advancedendoli@gmail.com.
Disclosure: Dr. McCormack reports no disclosures.
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