Retreatment vs Extraction and Implant: Making Sound Clinical Treatment Decisions

The Hippocratic Oath was written sometime between 500 and 300 BCE by Hippocrates. Its principles have survived to this day, and when dental students graduate, a dental version of the oath is often taken that reads something like this:

“As a student of dentistry and as a dentist, I will conduct myself with competence and integrity, with candor and compassion, and with personal commitment to the best interests of my patients. I shall care for my patients, as I would be cared for. The health and well-being of my patients will be my first consideration. I shall obtain consultation when it is appropriate. I shall include my patients in all important decisions about their care….”

As dentists, we face questions and challenges every day regarding our patients’ oral health. Oftentimes, there are cases that appear simple but end up being very complex (Figure 1). Every clinician should have a relationship with a specialist to assist in making appropriate treatment decisions. Becoming a “Super Generalist” should not be the goal of any general dentist. It does not do our profession or our patients any good if we don’t provide the most evidence-based and best clinical care possible. Unfortunately, in my opinion, these care concepts are becoming lost due to fast-paced production dentistry, high student loan debt, and no real accountability.

To extract the tooth or not is the million dollar question that many dentists frequently have to answer. In fact, most endodontically treated teeth are rarely extracted due to endodontic reasons (< 8.6%); they are primarily extracted as a result of restorative (32.0%) or periodontal (59.4%) failures.¹ The root canal procedure will only be as good as the restorative outcome and periodontal support (Figure 2). Technical advances and new dental materials in endodontics (such as mineral trioxide aggregate, surgical microscopes, microsurgical instruments, bioceramic technology, heat-treated NiTi files, ultrasonics, innovative irrigation techniques, and CBCT) have made it possible to save teeth that would have previously been extracted years ago.

Overall, Endodontics Has a High Success Rate
Endodontic therapy is the saving grace for millions of teeth each year and has a success rate of up to 97%.² Non-surgical retreatment root canal therapy has a success rate of up to 95%.³ However, there are times in which a retreatment case presents with problems or retreatment becomes impossible due to a separated instrument, a large post, or inadequate access. At that time, an apical surgery can be performed in order to try to save the tooth. In a comparison of surgical outcomes, Kim et al⁴ found a successful outcome of 95.2% for cases classified without a periapical lesion and 77.5% success with cases of endodontic-periodontal combined lesions. In addition, there are studies that compare the success rates of the general dentist (GP) performing a root canal vs an endodontist. Both have very high success rates. However, it was reported by Alley et al⁵ that the treatments provided by endodontists were statistically higher in success rate (98.1%) than those done by GPs (89.7%).

Post-treatment Disease
Post-treatment endodontic disease is occasionally an unfortunate reality. But that does not mean the tooth always requires an extraction and implant. Studies show that a restored endodontically treated tooth and a single-unit restored implant have similar success rates (94% and 95%, respectively). However, implant cases have more long-term post-treatment issues (such as abutment loosening and implants not properly osseointegrating) due to bisphosphonates and antidepressants as well as traumatic occlusion⁶ (Figure 3). Smoking, general health problems, and attachment levels have also been found to be important factors affecting bone loss around implants.⁷ A 5-year survival rate of 99% was found in a study in which all the patients treated with dental implants were healthy nonsmokers.⁸

Post-treatment disease was a term coined by Shimon Friedman. Instead of saying the root canal failed, could it be possible that the patient failed to heal?

Could it be possible that the crown is leaking? Could it be possible there is a missed canal, vertical root fracture, weak obturation, perforations, incomplete instrumentation, or inadequate irrigation during the original treatment (Figure 4)? Absolutely! However, there are some cases that were performed in textbook fashion, and the patient still did not heal completely. Likewise, there are cases that were carried out well below a scientifically acceptable standard and yet provided long-term success (Figure 5).

Post-treatment disease has 4 possible etiologies⁹:

1. Microorganisms that aren’t eradicated during previous treatment

2. Bacterial recontamination into the canal system

3. Microorganisms that survive in the apical tissues outside the canal system and are protected by a bacterial plaque or foreign body reactions in the apical tissues

4. The presence of true periapical cysts

Diagnosis and Treatment Planning Considerations
A thorough examination is necessary to make an accurate diagnosis prior to initiating retreatment. It is important to take very good diagnostic radiographs of various angles, including a bite-wing of the area in question. Bite-wing radiographs are useful for determining periodontal bone height and looking for caries under restorations or fractures. Even though radiographs may be a critical aid to the clinician, they should never be the sole support for a conclusive diagnosis since the information that they can provide is only one piece of the puzzle in determining endodontic etiology. The recent introduction of 3-D imaging has aided in endodontic treatment planning. If there is not enough information to make the proper clinical judgment from 2-D radiographs, limited field of view (FOV) CBCT is the imaging modality of choice for teeth with post-treatment disease (Figure 6).

Limited FOV CBCT is useful in:

1. Identifying untreated canals, root perforations, and separated instruments
2. Assessing complex anatomy, such as fused roots and resorptive defects
3. Visualizing bone loss patterns that are consistent with apical or marginal periodontitis and furcation involvement¹⁰

Using this technology, things can often be discovered that would give endodontic retreatment little or no chance of success, thus avoiding a procedure that would result in a negative outcome. However, CBCT does have its limitations:

1. The image resolution can’t pick up microcracks or small vertical root fractures. These are the Achilles’ heels in determining the longevity of a root canal-treated tooth.¹¹

2. CBCT images do not have high enough resolution around root-filled teeth or teeth with metal posts and crowns. Scatter and beam hardening continue to be a challenge compared to 2-D radiographs. If this scattering and beam hardening is within, or close to, the tooth being assessed, the resulting CBCT images will be of minimal diagnostic use.¹²

3. CBCT scans may be of minimal benefit in assisting with the location of a calcified canal as the resolution is significantly worse than that of a periapical radiograph. Therefore, if conventional radiography does not reveal a canal, it would not likely be visible with a CBCT scan. In addition, a recent study demonstrated that CBCT scans are not effective in locating the MB2 canals of maxillary molars compared to direct access.¹³

After making a diagnosis, it’s treatment decision time. There are essentially 4 options for treatment of a tooth that has post-treatment disease:

1. Do nothing

2. Extraction

3. Nonsurgical retreatment

4. Surgical treatment

Deciding whether or not to do nonsurgical or surgical retreatment to retain the tooth can be challenging. The American Association of Endodontists (AAE) has generated a guide to help clinicians with these topics called Treatment Options for the Compromised Tooth: A Decision Guide (available at aae.org/treatmentoptions). The decision to save a tooth is based upon the following: the restorability of the tooth, its strategic location, periodontal health, the patient’s health history, motivation, patient finances, and the skill level and experience of the dentist. When indicated, and when the teeth are treated properly, the complete healing rates for nonsurgical retreatment are high, ranging from 74% to 98%¹⁴ even in the presence of a seemingly immunocompromised patient with HIV (Figure 7). The patient’s quality of life and normal mastication is rapidly restored, and nonsurgical retreatment is more economical compared to an implant. Implant success is very high as well, but studies show they have more postoperative complications over 5 to 10 years. Mechanical complications, such as implant abutment loosening due to biomechanical overloading, screw loosening/implant fractures, and veneering porcelain fractures are to be considered.¹⁵ Biological complications, such as peri-implantitis, are also an issue. It usually takes about 5 years for peri-implant disease to progress and exhibit clinical signs and symptoms. Peri-implantitis is usually very difficult to completely eradicate.¹⁶

CLOSING COMMENTS
It is estimated that 15.1 million root canal treatments are performed annually. The AAE has found that 72% of nonsurgical endodontic procedures are done by GPs. In cases presenting with post-treatment disease, a referral to an endodontist for a consultation should be made. In cases where the tooth cannot be predictably restored or other issues exist, such as a poor crown-to-root ratio or extended periodontal concerns, then an extraction and implant placement can be considered. With current technology/training, endodontists are best equipped to address retreatment and ensure the best chance for patients to save their natural teeth for a lifetime (Figure 8).

References

1. Vire DE. Failure of endodontically treated teeth: classification and evaluation. J Endod. 1991;17:338-342.
2. Salehrabi R, Rotstein I. Endodontic treatment outcomes in a large patient population in the USA: an epidemiological study. J Endod. 2004;30:846-850.
3. Fristad I, Molven O, Halse A. Nonsurgically retreated root filled teeth—radiographic findings after 20-27 years. Int Endod J. 2004;37:12-18.
4. Kim E, Song JS, Jung IY, et al. Prospective clinical study evaluating endodontic microsurgery outcomes for cases with lesions of endodontic origin compared with cases with lesions of combined periodontal-endodontic origin. J Endod. 2008;34:546-551.
5. Alley BS, Kitchens GG, Alley LW, et al. A comparison of survival of teeth following endodontic treatment performed by general dentists or by specialists. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004;98:115-118.
6. Iqbal MK, Kim S. For teeth requiring endodontic treatment, what are the differences in outcomes of restored endodontically treated teeth compared to implant-supported restorations? Int J Oral Maxillofac Implants. 2007;22(suppl):96-116.
7. Baelum V, Ellegaard B. Implant survival in periodontally compromised patients. J Periodontol. 2004;75:1404-1412.
8. Bornstein MM, Schmid B, Belser UC, et al. Early loading of non-submerged titanium implants with a sandblasted and acid-etched surface: 5-year results of a prospective study in partially edentulous patients. Clin Oral Implants Res. 2005;16:631-638.
9. Farzaneh M, Abitbol S, Friedman S. Treatment outcome in endodontics: the Toronto study. Phases I and II: orthograde retreatment. J Endod. 2004;30:627-633.
10. Rodríguez G, Patel S, Durán-Sindreu F, et al. Influence of cone-beam computed tomography on endodontic retreatment strategies among general dental practitioners and endodontists. J Endod. 2017;43:1433-1437.
11. Patel S, Brady E, Wilson R, et al. The detection of vertical root fractures in root filled teeth with periapical radiographs and CBCT scans. Int Endod J. 2013;46:1140-1152.
12. Schulze R, Heil U, Groβ D, et al. Artefacts in CBCT: a review. Dentomaxillofac Radiol. 2011;40:265-273.
13. Parker J, Mol A, Rivera EM, et al. CBCT uses in clinical endodontics: the effect of CBCT on the ability to locate MB2 canals in maxillary molars. Int Endod J. 2017;50:1109-1115.
14. Friedman S, Mor C. The success of endodontic therapy—healing and functionality. J Calif Dent Assoc. 2004;32:493-503.
15. Goodacre CJ, Bernal G, Rungcharassaeng K, et al. Clinical complications with implants and implant prostheses. J Prosthet Dent. 2003;90:121-132.
16. Rashid H, Sheikh Z, Vohra F, et al. Peri-implantitis: a review of the disease and report of a case treated with allograft to achieve bone regeneration. Open Dent J. 2015;2:87-97.

Dr. Short earned his DMD degree in 1999 at the Medical College of Georgia School of Dentistry. He earned his postdoctorate degree in endodontics from Nova Southeastern University in 2002 and became a Diplomate of the American Board of Endodontics in 2009. Dr. Short is an expert consultant in endodontics for the Georgia Board of Dentistry, an author, a speaker, and an assistant clinical professor at the Dental College of Georgia in Augusta. His private practice, Apex Endodontics PC, is located in Smryna, Ga. He can be reached at dr.short@yahoo.com.

Disclosure: Dr. Short reports no disclosures.

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