Microscopes & Management of Root Canal Perforation

As discussed in Dr. Justin Parente's previous post, dental operating microscopes can prevent procedural error in endodontic treatment.

There are those who may debate this, but in my opinion, microscopes are the standard of care in endodontics. Molar endodontics should be done using a microscope. In our practice, we use microscopes on every case. Perforations happen, missed canals happen, but with a microscope (and other advanced imaging systems - but that is another post) they are much less likely to occur.

The following case is that of a root perforation, it's microscopic retreatment, repair using MTA and the 6 month recall showing healing.

This patient was referred to Superstition Springs Endodontics with the complaint of "constant pain on lower right". Our diagnostics found #30 with Prior RCT and symptomatic apical periodontitis (SAP). He reports that this root canal was done 1.5 yrs earlier by a general dentist.
As you can see in the radiograph, there is a large pa lesion on the distal root and a radiolucency in the furcation area - likely caused by furcal perforation.
We discussed options and recommended retreatment with probable perforation repair in the pulpal floor.

Upon access, we found a furcal perforation that had been covered with resin buildup material.

RCT retreatment was completed. By using a microscope, we were able to locate a 4th canal that had previously been left untreated in the distal root. We also repaired the pulpal floor perforation using MTA.

At 6 month recall, you can see that the periapical lesion has healed very nicely. The bone loss in the furcation area has also improved. The patient is functioning on this tooth and is asymptomatic. He occasionally reports some swelling adjacent to the tooth, but upon our clinical exam today, probings are normal and there is no sign of irritation or infection.

Prevention of root perforation is always better for the long term prognosis than perforation repair. Use of magnification and lots of light (microscope), understanding pulp & canal anatomy, proper use of high & slow handpieces and ultrasonics, recognizing buildup material from dentin of the pulpal floor are all important factors to help prevent root perforation. With that said, if perforation occurs, the patient should be informed and the perforation should be repaired immediately with MTA. Proper management following root perforation can allow the tooth to be retained. Endodontists are specialists in saving teeth.

The Dental Operating Microscope Prevents Procedural Errors in Challenging Teeth

In case you are a new reader, it merits repeating that the dental operating microscope is the most valuable tool available for providing endodontic care.  The light and magnification provided are critical to success.  With this post, I will present two recent cases where two different clinicians had difficulty locating canal anatomy and perforated the root structure.  Each case was originally treated by a general dentist within the last year or two. With the use of a dental operating microscope, I was able to locate the missed canals and repair the perforations.  Hopefully, our clinician readers who are not microscope trained will become motivated to invest in one.

Case 1

This patient described an on and off awareness of her tooth since root canal treatment by her general dentist.  Her symptoms began to worsen, and she noticed a bump on the gums that drained.  Her general dentist had admitted to difficulty locating a challenging ML canal.

Preoperative Distal Shift
Note the ML canal is obturated a few millimeters below the orifice.

Preoperative Straight
Note the furcation radiolucency and absence of apical problems.

There was no clinical sign of swelling or of a sinus tract at our appointment.  The tooth was tender to percussion and uncomfortable to palpation in the furcation area.  Probing depths were 2-3mm with some bleeding and serous drainage on probing in the furcation area on the buccal.

A diagnosis of previous root canal treatment with a chronic furcation abscess was made.  I discussed the findings and treatment options at length with the patient.  When a perforation exists for a long time and then becomes infected, our success rate with retreatment drops by some indeterminate margin, and the treatment was not without risk.  The patient opted to take a chance on saving her tooth.

Upon access, purulent drainage was found pushing up from the gutta percha in ML area.

Upon removal of the gutta percha, a perforation was found that drained. 

After irrigating the perforation site with saline, and drying, the ML canal was located lingual to where the previous clinician had been looking.  It was high on the wall.

I was surprised to find the ML canal to not merge with the MB canal.

The location of ML was confirmed.  (ML not MB2!)

After two weeks of calcium hydroxide treatment, the patient returned symptom free and with improvement in the periodontal health.  You can see on our post op radiographs just how large the perforation was.

At a second visit two weeks later, the canal was obturated and the perforation repaired with MTA.
While the MTA extruded into the furcation is not ideal, the area should continue to heal.

Post operative image distal shift.

At a follow up visit, the patient remained symptom free and the periodontal health continued to look good.  The extruded MTA does not appear to have affected the outcome, which is consistent with the findings of others. For example, see this case of a large furcation perforation repair by Dr. Hales: http://www.theendoblog.com/2008/06/herodontics.html

Case 2

This patient initially presented with a chief complaint of minor soreness to bite forces and an intermittent dull pressure ache that she described as emanating from between the teeth #13 and #14.  Her symptoms were described as unchanged with root canal treatment by her general dentist within the last six months.  She described an improvement in symptoms when flossing and flushing between her teeth with Peridex.

Preoperative image.

The tooth was slightly tender to bite forces and percussion, but there was again no signs of swelling or a sinus tract. The probing depths were 2-3mm with a 7mm pocket on the MB and a 6mm pocket on the DB.  Because of the bilateral probing and bone loss, and the symptoms unchanged with root canal treatment, I recommended a periodontal evaluation.  I knew that there was an untreated MB2, but the periodontal symptoms did not match up.  After periodontal treatment, the pocket on the distal resolved, and there was a short-term improvement in symptoms, but they soon returned.  At this point, I was suspicious of a perforation.  A CBCT would certainly help confirm the diagnosis and be of value, but a decision was made to access and investigate.

Upon access, gutta percha was found in the location of the MB2.  Beneath, a perforation was found, just as in the previous case.

A file was inserted and a radiograph taken to confirm the perforation location.

Here you can see a 6 file entering the true MB2 canal.  It was located angling toward the mesial and buccal from the perforation.

The canal opened up a little.

A file inserted confirms the MB2 location.

Now, the MB2 can clearly be visualized after proper orifice shaping.

A gutta percha cone was inserted into the canal, and the others blocked with cotton while MTA was used to repair the perforation.

At the first visit, the patient was made aware of a fracture from the mesial to the distal that dramatically decreased the prognosis for the tooth.   After the first visit, the patient's symptoms resolved, and she could chew comfortably.  A case could be made to have the tooth immediately extracted, but the patient opted to finish the treatment even with the uncertainty involved.

Unfortunately, this tooth also exhibited a fracture across the floor of the pulp chamber.  These fractures are  very bad for the longevity of the tooth. 

Post operative radiograph

In each of these cases, it is clear from the preoperative radiographs, that the clinicians who originally treated these teeth had good command over the processes of instrumentation and obturation.  Both cases are instrumented to length (with the exception of the DB of #14), and appear well obturated with Thermafil carriers.  Both clinicians were aware of the missed anatomy, but could not locate the ML and MB2 canals respectively.  They were certainly difficult ones to find; they were not immediately obvious upon access, and while I do have extra training in endodontics, the microscope is what enabled these teeth to be saved.  The long-term prognosis of either tooth is not great, especially the fractured #14, which could fail in the short-term, but the patient's were well educated and appreciate the risks involved.  The patient with tooth #14 is now prepared for the eventuality of a dental implant in that site.

The success of perforation repairs depends on many factors, such as the time since perforation, the location within in the tooth, the size of the perforation, and the materials used for repair.  The smaller and more recent the perforation, the better the chance of success.  The farther apical the perforation, the generally better success with repair, as long as the true canal path can be recaptured.  Furcation perforations are the easiest to access for repair, and have the best surrounding tooth structure.  Perforations in the gingival attachment level have a decreased prognosis due to difficulty controlling materials and the increased risk of a periodontal defect.  In the Toronto studies (Friedman 2004), a prospective longitudinal study of the success of endodontic retreatment, of the 8 cases, roughly half of the retreatments with perforation exhibited healing.  However, the materials used for repair in this this study were glass ionomers.  In another study, 16 out of 16 cases repaired with MTA exhibited healing at a minimum of 1 year (Torabinejad 2004).

For tips on the placement of MTA, see this other post by Dr. Hales: http://www.theendoblog.com/2008/04/placement-of-mta.html

Example of a case of perforation repair in the lateral gingival attachment.  I used MTA for this case, and the perforation was repaired non-surgically.  The patient's restorative dentist used glass ionomer as a restoration on top. A case for a different treatment plan involving crown lengthening could be made.

All three teeth in this posted here I consider to have guarded long-term prognosis.  However, all three patients continue to chew and function in the absence of disease.  If you have any questions or input, please let us know.

Any suggestions for future topics or posts are also welcome!



Farzaneh M, Abitbol S, Friedman S. Treatment Outcome in Endodontics: The Toronto Study.  Phases 1 and 2: Orthograde Retreatment. J Endod. 2004;30: 627-33.

Main C, Mirzayan N, Shabahang S, Torabinejad M. Repair of root perforations using mineral trioxide aggregate: a long-term study.  J Endod. 2004;30: 80-83.

Root Canals and Dental Implants: The Rest of the Story

At a recent local implant seminar, the clinician speaker, a representative of a leading implant manufacturer, reportedly told the audience that endodontic retreatment had a success rate of 46% in comparison to implant success rates at 98%. This speaker was terribly misinformed or choosing to misrepresent endodontic retreatment in an effort to promote implant placement on behalf of the implant manufacturer.

A recent blog post discussed a recent surge of misinformation regarding endodontic retreatment among the general population as well as the dental community. Anyone close to the dental industry is familiar with the massive marketing efforts of the implant manufacturers. Typically, these marketing efforts are in the form of clinician representatives speaking on behalf of the implant manufacturer in a continuing education presentation.

As endodontists, it is our responsibility to educate the public and our professional colleagues regarding this issue.

To see the outcomes evidence regarding retreatment, click here. (an accurate estimate of retreatment success is 80-85%)

That is not the only point that is misrepresented by implant marketers. There are some important points that are routinely overlooked when comparing endodontic and implant research. You will not hear these points at your next implant seminar.

Teeth and Implants are not the same which makes direct comparison difficult.

• Teeth are natural, have a periodontal ligament for proprioception, are asked to carry tremendous occlusal forces and failure is usually due to infection.
• Implants are man-made, do not have a periodontal ligament for proprioception, are usually given light occlusion and failure is usually due to inflammation or biomechanical forces disrupting the osseointegration (fusion of implant to the bone)

Success is defined differently.

• Root canal success has traditionally been defined as a tooth that is fully functional, with no symptoms or signs of infection (drainage or sinus tracts) including complete radiographic healing.

• Implant success has traditionally been defined by much less stringent criteria. Many studies define implant success as simply implant survival - meaning still in the mouth.

In a systematic review of outcomes of single implants and endodontically treated teeth, Iqbal and Kim (2007) restricted their outcome measurement to survival. After reviewing 13 studies involving RCT, 55 studies with implants, and 1 study directly comparing the two, their meta-analysis found 94% survival of RCT and 96% survival of single implants at 5 years. Their study revealed no significant difference between the root canals and single implants.

After reviewing the root canal and implant outcomes, Zitzmann et. al. (2009) noted, "Due to similar outcomes of implant treatment and RCT, the decision to treat a tooth endodontically or replace it with an implant, must be based on factors other than anticipated treatment outcome alone."

Comparing endodontic "success" with implant "survival" is like comparing apples and oranges. There are also a number of differences between endodontic and implant studies which may make proposed implant "success" rates artificially high. The following are a few examples.

Treatment Failure

• In root canal studies, failure is typically defined as any sign or symptom of infection or failure to heal radiographically. A tooth may be fully functional and asymptomatic, but considered "failing".

• In implant studies, implant failure is divided into early failures (failure during the healing period or loading) and late failures (failures after osseointegration). Many implant studies fail to include the early failures in the results of the study. For example, in a 2010 study by Lee et al. "any implant that was not set in the final prosthetic was excluded".

These are two VERY different ways of determining statistical success. If you remove any early failure, your statistics at the end of the study are skewed and misleading.

Periodontal Ligament

• Root canal treatment preserves the periodontal ligament and the important relationship with the alveolar bone. If you lose the ligament, you will lose bone. The periodontal ligament is the home to important cells such as osteoclasts, osteoblasts, fibroblasts, cementoblasts, cementoclasts, undifferentiated mesenchymal cells (stem cells). These cells are all important in the dynamic relationship between the tooth and the bone. These cells are important in orthodontic movement or extrusion. The periodontal ligament and its associated cells may be the best way to preserve bone and stimulate bone growth. Preserving the tooth and its periodontal ligament preserves preserves the crestal bone.

• Loss of crestal bone around a dental implant is expected over time. Lundgren (2011) states that "some continuous loss of marginal bone is generally accepted, but the question remains as to what extent it must occur". Significant crestal bone loss can compromise prognosis and lead to failure. Loss of crestal bone also creates esthetic issues that are difficult to resolve. The location of the abutment interface to the crestal bone, the crown/implant ratio and the non-axial forces placed on the implant and bacterial affinity for the implant surface are some of the possible reasons for crestal bone loss. Patients should be informed of the expected loss of crestal bone following implant placement the the potential effect that may have on the prognosis and esthetics over a long period of time.

To review the importance of the periodontal ligament, click here.


Restorative Failures

• In endodontics, it is common knowledge that restorative failure is a common reason for endodontic failure. Any bacterial leakage from recurrent decay, open margins, untimely restoration of the tooth is usually defined as a "failed"root canal. In all fairness, in this situation, the restorative failure caused the root canal failure.

• In implants, restorative failure is also a challenge. Hannahan et. al. (2008) reported that while outcomes are almost identical, "implants required additional intervention more frequently than endodontically treated teeth." Fractured porcelain, loose abutment screws and improper angulation of implant preventing proper restoration are all restorative complications/failures that are not typically considered when discussing implant success/failure. Roos-Jansaker et. al. (2006) also reported progressive peri-implant bone loss associated with soft tissue inflammatory response as a "common" occurance in implants.

• We typically do not consider esthetic failures, but with the expected marginal bone loss around a dental implant in the anterior esthetic zone, patients need to be informed of the potential changes in the marginal bone and corresponding gingival tissue over time. While this tooth may be fully functional, and integrated, the esthetics could be considered a failure.

Patients who think that removing a tooth and replacing it with an implant will resolve all their dental problems are mis-informed.


Patient pools are different.

• Root canal studies typically include all patients.

• Implant studies typically exclude patients with systemic disease, poor quality bone, removable prosthesis, smokers, alcohol abuse, diabetes and parafunctional habits etc.

Bain et. al. reported the comparative incidence of implant failure in smokers vs. non-smokers at 11.28% to 4.28% and De Bruyn et. al. reported the same at 31% to 4%.

These are two VERY different groups of patients. Exclusion of non-ideal patients in a study likely creates a higher "success" rate than would be seen in an average population.

Occlusal Forces

• Root canal therapy allows the natural tooth to remain in full normal function immediately following the procedure.

• Implant therapy removes the tooth from function during integration and typically restored to a light occlusion with minimal excursive contacts.

These are two VERY different types of occlusal function. Once again, because teeth and implants are not the same, we ask and expect very different type of function from each group.

Specialist vs. Generalist

In any study, it is important to look at the clinicians performing the study. Are the procedures performed by dental students, residents, general practitioners or specialists? Historically, many endodontic studies have been performed by dental students. It is well known that general dentists perform a majority of the root canals every year. Hull et. al. (2003) reported that according to the dental claims in Washington in 1999, 64.7% of the root canals were performed by general dentists. Alley et. al.(2004), in a survey of survivability regarding root canals done by general dentists and specialists, reported that the specialist had significantly greater success (98.1%) than the general dentists (89.7%). In contrast, most dental implants have historically been placed by specialists. With the growing trend of implant placement by general dentists, the success rates previously reported cannot be assumed accurate in the clinical setting by general dentists.

Not all research is equal.

We all want to make sure that our treatment recommendations are in line with current scientific evidence. However, not all scientific studies provide the same level (quality) of evidence. Melnyk's hierachy of evidence ranks the quality of evidence based upon the type of study performed. For example, systematic review or randomized, controlled, double blind study has the highest level of evidence, while on the other hand, an expert opinion, is at the other end of the spectrum and provides the lowest level of evidence. In a systematic review of the endodontic literature, Torabinjad et. al. (2005) examined endodontic articles related to the success of endodontic treatment and found only 6 of 306 articles that were considered in the highest level (level 1 of 5) of evidence (randomized, clinical trials). 26 were considered level 2 (low quality randomized control trials, cohort studies), 5 were level 3 (case-controlled studies, systematic review of case-controlled studies), 82 were level 4 (low quality cohort studies, case-control studies, case series), and 178 were level 5 (case reports, epidemiological studies, expert opinion, literature reviews). This does not reflect well for evidence based treatment recommendations based upon this body of evidence. However, Torabinejad et. al. (2007), in another systematic review of outcome studies involving root canals and single implants found that the quality of endodontic studies higher than that of the implant studies, which were case series analysis 64% of the time. Erkert et. al. (2005) reported that the six major ADA-certified dental implant manufacturers, when asked for research validating their implant system, submitted evidence generally derived from level 4 case series studies, rather than controlled clinical trials or cohort studies.

As professionals, we are responsible for understanding and interpreting the scientific research in order to provide our patients with evidence based treatment recommendations. With much of the current continuing education provided/sponsored by the dental industry, we are tasked with the responsibility of deciphering what is marketing hype from what is valid, scientific, data.

In our practice we routinely recommend implant therapy for patients who have missing teeth or teeth that are non-restorable. If you are unsure regarding the restorability of a tooth, team up with your endodontist. He/She should have the technology, including microscopes and CBCT and experience to help make this important decision.

References

Alley BS, Kitchens GG, Alley LW, Eleazer PD (2004) "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, 98, p 155-188.

Bain CA, Moy PK. (1993) "The Association Between the Failure of Dental Implants and Cigarette Smoking" Int J Oral Maxillofac Implants, 8, p. 609-615.

De Bruyn H, Collaert B (1994) "The Effect of Smoking On Early Implant Failure", Clin Oral Implants Res, 5:4, p. 260-264.

Doyle SL, Hodges JS, Pesun IJ, Baisden MK, Bowles WR. (2007) "Factors Affecting Outcomes for Single-Tooth Implants and Endodontic Restorations", JOE 33:4, p. 399-402.

Ekert SE, Choi YG, Sanches AR, Koka S. (2005) "Comparison of Dental Implant Systems: Quality of Clinicial Evidence and Prediction of 5 Year Survival" Int J Oral Maxillofacial Implants 20, p. 406-415.

Hannahan, JP, Eleazer PD (2008) "Comparison of Success of Implants versus Endodontically Treated Teeth", JOE 34:11, 1302-1305.

Hull TE, Robertson PB, Steiner JC, del Aguila MA. (2003) "Patterns of Endodontic Care for a Washington State Population", JOE 29, 553-556.

Iqbal MK, Kim S. (2007) "For Teeth Requiring Endodontic Treatment, What Are the Differences in Outcomes of Restored Endodontically Treated Teeth Compared to Implant-Supported Restorations?" Int J Oral Maxillofacial Implants 22(suppl.), 96-116.

Lee, Eui-Hee, Ryu, Sun-Mi, Kim, Jwa-Young, Cho, Byoung-Ouck, Lee, Yong-Chan, Park, Young-Ju, Kim, Seong-Gon. (2010) "Effects of Installation Depth on Survival of an Hydroxyapatite-Coated Bicon Implant for Single-Tooth Restoration", JOMS 68:6, 1345-1352.

Lundgren LL, (2011) "Marginal Bone Level Changes at Dental Implants After 5 Years in Function: a meta-analysis", Clin Implant Dent Relat Res 13(1), p. 19-28.

Roos-Jansaker AM, Renvert H, Lindahl CH, et. al. (2006) "Nine to Fourteen Year Follow-Up of Implant Treatment: Part III" J Clin Periodontology 33, p. 296-301.

Torabinejad M, Kutsenko D, Machnick TK, IsmailA, Newton CW. (2005) "Levels of Evidence for the Outcome of Nonsurgical Endodontic Treatment" JOE 31, p. 637-646.

Torabinejad M, Anderson P, Bader J. et. al. (2007) "Outcomes of Root Canal Treatment and Restoration, Implant-Supported Single Crowns, Fixed Partial Dentures, and Extraction Without Replacement: A Systematic Review". J Prosth Dent 98, p. 285-311.

Zitzman NU, Krastl G, Hecker H, Walter C, Weiger R. (2009) "Endodontics or Implants? A Review of Decisive Criteria and Guidelines for Single Tooth Restorations and Full Arch Reconstructions", International Endodontic Journal 42:9, p.757-774.