Implant Wisdom: An Endodontist’s Approach

INTRODUCTION
As a practicing endodontist for more than 25 years, I have seen the incorporation and transformation of implant dentistry into clinical practice. All specialties of dentistry have benefitted in multiple ways. Treatment plans have become multidisciplinary in nature. Complex and invasive procedures are now more routine and predictable. Aesthetic demands are being met with the incorporation of 3-dimensional (3-D) analysis within all phases of treatment planning, surgery, and prosthetic rehabilitation.
However, it is my contention that a gap exists in preimplant diagnosis, and there needs to be an evidence-based approach. Implant treatment planning should begin when an individual abutment is deemed nonrestorable, or when its success rate is unacceptable or unpredictable. Instead, anecdotal information is used routinely in dentistry to condemn certain abutments in favor of implant placement. An evidence-based approach would allow a more complete appreciation of abutment success or failure.

The Role of the Endodontist
An endodontist has a unique ability and perspective in the critical analysis of any individual tooth. The enhanced use of surgical microscopes and illumination allows clinical visualization of pathology, fractures, and broken instruments. During the past decade, cone beam computed tomography (CBCT) has become an indispensible part of routine endodontic care and will soon become a necessary armamentarium addition. A CBCT is not a replacement for conventional radiography.¹ This technology offers surprisingly low amounts of absorbed radiation.2 A CBCT with a small field of view (FOV) (such as the PaX-Duo3D (Vatech) used in my office) allows for hundreds of images to be taken at one time within seconds. This 3-D image can then be reconstructed to allow for visualization and diagnosis in all 3 dimensions. The information encapsulated in this FOV gives the clinician data not possible to attain from any other source. This ability to see in the third dimension standardizes care and turns anecdotal information into an evidence-based approach to dental delivery.^1-4 I have often called this technology virtual surgery. In addition, the exposed radiation to the patient depending on the FOV can be as low as 2 or 3 digital dental radiographs. It is my contention that incorporation of a CBCT scan, on a case-selective basis in order to determine abutment restorability or success, is a necessary part of preimplant diagnosis.
If the cornerstone of our profession is to retain our patients’ natural dentition, then every effort should be made by general dentists and specialists to offer treatment plans that are building blocks to help in that endeavor. Natural teeth should not be viewed as space savers for future dental implants. Of course, complex anatomy or prosthodontic consideration can, at times, alter this philosophy. However, it is my contention that certain abutments are being sacrificed without an accurate preimplant abutment prognosis and incorporation of the entire multidisciplinary team.

An Evidence-Based Approach is Clearly Required
So where do we begin? It is clear that as professionals, we must be guided by evidence-based, scientific fact; and not on comments like, “that won’t work” or “in my hands, that choice works best.” As an endodontist who incorporated implant dentistry into my practice years ago, I can visualize various alternatives to my patients and offer a unique perspective in this arena. My goals are to try to save every tooth with an endodontic issue. However, I am equally capable of determining abutment success or failure and switching treatment options to implant dentistry, once a complete preimplant diagnosis and prognosis is made.
Many studies have consistently determined that endodontic success is equal to implant success at around 95%. Therefore, a decision whether to do endodontic therapy or place an implant needs to be made on factors other than treatment outcome.⁵ A goal of evidence-based dentistry is to establish appropriate treatment decisions based on the best available clinical evidence, the individual factors of each particular case, the clinician’s expertise, and the patient’s informed consent.⁵ It should be clear to all our dental colleagues, unless there are extenuating circumstances, that routine endodontic treatment should be instituted as a first choice option before extraction and dental implant placement.
There are a number of key factors that need to be considered in depth and may alter our treatment plan (Table).

The age of a patient should not be viewed as a negative in determining whether endodontic pathology will heal more slowly in older adults. In most circumstances, unless a patient is medically compromised, success rates are statistically similar with a younger adult. Advancing age of a patient may actually be a negative factor in influencing us not to perform multiple surgical procedures such as extraction, bone grafting, and eventual surgical placement of a dental implant in certain older adults.
The size of an endodontic lesion does not in most cases determine degree of success. In other words, a large periapical lesion should not mean low endodontic success. This is especially true in single-rooted teeth, where there isn’t a large dehiscence through the buccal cortex. In multirooted teeth, periapical lesions that extend into furcations may alter success rates deleteriously.
Abutment analysis becomes more complex when analyzing success of previously treated endodontic teeth. Multiple options are always being considered, including retreatment, apicoectomy, and extraction and implant placement. It is critical to first understand why an individual tooth has failed. A CBCT needs to be an integral part of this diagnosis. Unfortunately, it often appears that a perfunctory diagnosis of endodontic failure is made with a “cookbook” formula for then simply extracting that tooth. Oftentimes, a thorough analysis will show either missed extra canals, which can be deemed patent with a CBCT and therefore retreated with a high success rate. There is also strong evidence that a sizable number of endodontic failures are truly prosthodontic failures caused by leaky restorations. It is the quality of the permanent restoration that serves as an important predictor of long-term success of root canal treatment.⁵ These failures can also be corrected with retreatment since bacterial invasion can be arrested with disassembly of ill-fitting restorations and retreatment of the root canal system all with a high success rate.
Endodontic retreatment may have a guarded or poor prognosis when it is clear that iatrogenic issues make it impossible to offer the patient an ideal result. Crack lines that are clinically evident extending to or below the cemento-enamel junction make implant therapy a better option. A CBCT analysis, with verified crack lines subcrestal, also make endodontic retreatment a poor choice.
Another treatment alternative with failing endodontic teeth is an apicoectomy. This treatment modality seems to be in disfavor amongst a growing number of our dental colleagues. There appears to be a misconception of the true success rate of an apicoectomy. In case specific situations, an apicoectomy gives our patients a relatively high success rate with minimal bone destruction. Utilization of surgical microscopes and microinstrumentation and microsutures allows for minimal osseous destruction. An apicoectomy may be a primary treatment choice in certain medically compromised patients who cannot have an implant placed. This treatment choice is a cost-effective procedure that does not necessitate further prosthetic costs after the surgical procedure, as would extraction and implant placement.
A patient’s parafunctional habits must be addressed during an abutment analysis, because those same habits will be there after an extraction as well. Bruxism, extensive recession, mobility, and a person’s genetic biotype must all be critically interpreted at a comprehensive consultation. In these complex situations, a multidisciplinary approach is mandatory before a final decision is made about an abutment’s long-term success. In essence, without a clear diagnosis, failure will ensue whether it is of an endodontic, prosthodontic, or implant derivation.
There is no exact formula to determine abutment success or failure. What is necessary is the incorporation of vital data into the analysis so that objective criteria can be utilized in determining the best treatment plan for every patient.
Let’s look at some clinical cases exemplifying an approach that is balanced in assessing abutment versus implant treatment plans.

CASE REPORTS
Case 1
This case involves a patient who had successful endodontic treatment on tooth No. 13 in August of 2000 (Figures 1a and 1b). Ten years later, the patient returned to my practice with a very large radiolucency circumscribed around teeth Nos. 12 and 13 (Figure 1c). This patient had been told that both teeth were not restorable and that extractions and implant therapy were his best treatment option. A CBCT scan was taken and, although it was extremely large, it did not penetrate into the maxillary sinus or the palatal cortex (Figures 1d and 1e). A complete analysis did not reveal a vertical fracture of either abutment.
A decision was made to do an apicoectomy along with guided-tissue regeneration (Figures 1f and 1g). A 2-year follow up reveals complete healing and quality bone regeneration above Nos. 12 and 13 (Figure 1h). This case represents a good example to verify that the size of a lesion does not correlate well with success rate. An accurate and complete preimplant diagnosis prevented this patient from losing 2 natural teeth.

Figure 1a. (Case 1) Dexis 8/18/2000: Tooth No. 13 periapical radiograph reveals carious exposure; patient referred for root canal treatment.	Figure 1b. (Case 1) Dexis 8/25/2000: Tooth No. 13 routine endodontic therapy was completed.
Figure 1c. (Case 1) Dexis 8/2/2010: Development of large PAP, teeth Nos. 12 and 13. Patient was told by another dentist that both teeth should be extracted and implants placed.	Figure 1d. (Case 1) CAT scan: Due to complexity and size of lesion, a cone beam computed tomography (CBCT) scan reveals 1.5 cm x 1.5 cm cystic lesion.
Figure 1e. (Case 1) CAT scan: Although the lesion is extremely large, it does not penetrate the maxillary sinus or the palatal cortex and is circumscribed.	Figure 1f. (Case 1) Dexis 8/5/2010: Decision was made to do an apicoectomy on teeth Nos. 12 and 13.
Figure 1g. (Case 1) Dexis 8/5/2010: Guided-tissue regeneration and bone graft performed during surgical procedure.	Figure 1h. (Case 1) Dexis 2/21/2012: Complete resolution of periapical lesion with normal osseous trabeculation.

Case 2
A patient presented to our practice with tooth No. 19 having +2 mobility and was depressible in the socket. A thorough clinical and radiographic examination revealed this tooth to be necrotic. A J-shaped lesion surrounding the distal root with probing to the apex was verified (Figure 2a). The patient was previously presented with a treatment plan that included extraction and implant placement due to a concern of a vertical fracture. Upon examination, it was determined that this tooth had a good success rate. She did not have any other generalized periodontal problems and her contralateral tooth was intact. The patient agreed with conservative endodontic therapy, which was completed in our practice (Figure 2b). Upon recall examination, this large and suspicious lesion resolved uneventfully because the preimplant diagnosis showed this lesion to be completely of endodontic origin (Figure 2c).

Figure 2a. (Case 2) Dexis 8/9/2012: Pre-op +2 mobility, necrotic, depressible in socket, no vertical fracture seen.	Figure 2b. (Case 2) Dexis 8/20/2012: Conservative endodontic therapy performed.

Figure 2c. (Case 2) Dexis 2/21/2013: Recall revealed complete healing of PAP due to lesion being of endodontic origin.

Case 3
A 13-year-old male presented to our practice in September 2011 with massive swelling in the maxillary left anterior region, obliterating the mucobuccal fold. A previous history of trauma was verified, but the clinical and radiographic exam did not support a diagnosis of cracked tooth (Figure 3a). Tooth No. 10 was evaluated and pulp tested (EPT) nonvital. Due to the size of the lesion, a CBCT was taken (Figure 3b). A multidisciplinary conference and treatment plan were developed with the pediatric dentist and oral surgeon; this included a one-visit root canal, with a concomitant apicoectomy performed by the oral surgeon. The CB revealed the lesion to be tremendous in size, measuring approximately 3 cm x 2 cm and extending almost to the palatal cortex. Both the oral surgeon and our office coordinated treatment and root canal therapy (RCT), and apicoectomy was done on September 26, 2011 (Figure 3c). A 6-month follow up verified the quality healing in the No. 10 periapical area, but a periapical radiolucency now appeared around tooth No. 9 (Figure 3d). EPT verified a diagnosis of necrotic pulp. Conservative endodontic therapy was done in March 2012 (Figure 3e). A recall radiograph in January 2013 clearly shows complete healing of lesions apical to both teeth Nos. 9 and 10 (Figure 3f).

Figure 3a. (Case 3) Dexis 9/21/2011: A 13-year-old male presents with tremendous swelling obliterating the mucobuccal fold localized to No. 10. History of trauma and tooth was necrotic on EPT.	Figure 3b. (Case 3) CAT scan: CBCT revealed 3 cm x 2 cm lesion almost perforating palatal and sinus cortex. A multidisciplinary approach with pedodontist and oral surgeon was developed including one visit root canal therapy, and apicoectomy and marsupialization of lesion.
Figure 3c. (Case 3) Dexis 9/26/2011: One visit root canal therapy performed prior to same day referral to oral surgeon.	Figure 3d. (Case 3) Dexis 3/26/2012: Dramatic healing around tooth No. 10, but PAP now appears around No. 9. EPT verified necrotic pulp.
Figure 3e. (Case 3) Dexis 3/29/2012: Root canal completed on tooth No. 9.	Figure 3f. (Case 3) Dexis 1/3/2013: Recall reveals complete healing of teeth Nos. 9 and 10.

Case 4
A patient, referred by her restorative dentist, presented for RCT on tooth No. 21. Clinical and radiographic examination revealed external resorption on the buccal extending close to the crest of bone (Figure 4a). Moderate periodontal disease existed in this quadrant, including some loss of furca bone around tooth No. 19. In order to ascertain a complete picture of this lesion, a CBCT was taken, which verified the extent of tooth destruction and level of resorption to the crest of bone No. 21 (Figures 4b and 4c). Two treatment options were presented, which included RCT, crown-lengthening surgery followed by restoration with a crown. A second option was extraction and implant placement. After careful analysis and consultation with the restorative dentist, it was determined that crown lengthening surgery in the quadrant to expose healthy root structure could possibly jeopardize bone levels of adjacent teeth. Therefore, extraction and implant placement was performed in this case as a best alternative (Figures 4d to 4g).

Figure 4a. (Case 4) Dexis 10/5/2011: Patient was referred for root canal therapy on tooth No. 21. Clinical and radiographic exam revealed external resorption on buccal extending close to crest of bone.

Figure 4d. (Case 4) Dexis 10/19/2011: Extraction and bone graft of tooth No. 21 site.	Figure 4e. (Case 4) Dexis 2/7/2012: A 4-month healing showing intact graft and good osseous healing.
Figure 4f. Case 4 Dexis 6/5/2012: Tapered Groovy (Nobel Biocare) dental implant placed, stage II visit.	Figure 4g. Case 4 Dexis 6/5/2012: Tapered Groovy (Nobel Biocare) dental implant placed, stage II visit.

Case 5
A patient in severe pain was referred for RCT on tooth No. 30. Clinical and radiographic examination revealed a tooth painful to touch with mucobuccal swelling. Evaluation and pulp testing revealed necrotic pulp. A large radiolucency existed periapically as well as in the furcation (Figure 5a). This tooth was also painful on release of a tooth sleuth. A tentative diagnosis of acute abscess with a cracked tooth syndrome was made. It was suggested that a definitive diagnosis could be more clearly ascertained with the removal of a clinical crown. Upon removal of this old restoration, a clear mesiodistal crack line was visualized. Unfortunately, we were able to place an instrument through this crack into the furca (Figure 5b). The patient was told that this tooth was not restorable and treatment options were discussed including a 3-unit bridge versus a dental implant. The patient chose to have this tooth extracted and the site grafted for a future dental implant (Figure 5c). Complete resolution of the acute abscess and good bone healing can be seen at stage II uncovering (Figure 5d). This patient benefitted from a sequential approach to diagnosis and treatment, and was able to have the extraction and grafting done on the same day, minimizing multiple office visits.

Figure 5a. (Case 5) Dexis 12/1/2011: Patient was referred for root canal therapy due to pain in tooth No. 30. Pre-op large PAP and furca radiolucency—no pocketing evident, although pain on release of tooth sleuth.	Figure 5b. (Case 5) Dexis 12/22/2011: Removal of crown was suggested to verify MD crack—a clear crack line existed with ability to penetrate crack into furca. This tooth was deemed nonrestorable.
Figure 5c. (Case 5) Dexis 12/22/2011: Surgical extraction of fractured segments was performed on same day to alleviate pain, minimize excessive trauma to area. Bone graft was placed into socket.	Figure 5d. (Case 5) Dexis 09/10/2012: Stage II uncovering of Replace Tapered Groovy (Nobel Biocare) 5 x 10 dental implant.

CLOSING COMMENTS
Implant dentistry has become a fantastic and predictable treatment choice in dental practices today. As all pendulums swing back and forth, it is my contention that not all cases warrant extraction and implant placement. When a multidisciplinary approach is utilized, with all dental practitioners involved in an evidence-based approach, a more objective treatment plan will be realized. CBCT should become a gold standard in complex treatment decisions involving abutment success or failure. An endodontist’s unique perspective in dealing with these complex or strategic teeth offers the patient and restorative dentist the necessary objective information to help determine the most appropriate treatment plan for any compromised abutment.

References

1. The SEDENTEXCT Project. Radiation protection: cone beam CT for dental and maxillofacial radiology. Provisional guidelines (v1.1, May 2009). sedentexct.eu/system/files/sedentexct_project_provisional_guidelines.pdf. Accessed April 26, 2013.
2. Ludlow JB, Ivanovic M. Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;106:106-114.
3. Roth JS. CBCT technology: endodontics and beyond, Part 2. Dent Today. 2011;30:78-83.
4. Nesari R, Rossman LE, Kratchman SI. Cone-beam computed tomography in endodontics: are we there yet? Compend Contin Educ Dent. 2009;30:312-318.
5. American Association of Endodontists. Treatment planning: comparing the restored endodontic tooth and the dental implant. Endodontics: Colleagues for Excellence. Summer 2007:3-4.

Dr. Roth maintains a full-time endodontic practice in Manhattan, NY. He is a Diplomate of the International Congress of Oral Implantology, an assistant clinical professor at Columbia College of Dental Medicine, a Fellow of the American College of Dentists, consultant at the Manhattan Veterans’ Administration Hospital, and serves on the dental advisory board of Dentistry Today. He lectures extensively on various topics in endodontics and implantology. He can be reached at (212) 838-2011 or drroth@newyorkendodontics.com.

Disclosure: Dr. Roth reports no disclosures.