Using CBCT to Identify Vertical Root Fractures - Use of Filters

When we incorporated CBCT at Superstition Springs Endodontics, we hoped that it would be useful in identifying vertical root fractures.  There is a significant learning curve with the use of CBCT and identifying vertical root fractures may be one of the most difficult things to interpret.  The partnership with a good oral radiologist has also been an important part of learning to interpret CBCT.

In the past we have had to use clinical judgement, including presence of long, narrow periodontal pockets, j-shaped lesions as possible signs of vertical root fracture. However, those signs alone may also be caused by other conditions, not related to root fracture. Microscopic visualization was the most certain way to make this diagnosis. Too often, vertical root fracture is used as an excuse to remove a tooth without adequate evidence.

After more than two years of experience using high resolution, focus field CBCT in root fracture diagnosis, many consultations with the OMF Radiologist, we are more comfortable in diagnosing root fracture using CBCT, but the reality is that it is not always possible to see root fractures using CBCT.

Since the diagnosis of vertical root fracture (VRF) typically leads to extraction, it is our responsibility to be confident in that diagnosis.  In order to definitely see a root fracture using CBCT, it seems the fracture has to open up to some degree.  The more separation between fractured pieces, the better chance of making a definitive radiographic diagnosis. However, most vertical root fractures I see, do not have separated pieces.

Another challenge with identifying root fractures with CBCT is interpreting the difference between artifact (radiographic scatter) and actual fracture in the root.

Sometimes, a fracture cannot be seen with CBCT, but the bone loss pattern adjacent to a fracture can be seen. These bone loss patterns, not evident in traditional 2D imaging, can help identify the presence of a vertical root fracture.  Even with CBCT, all information has to be evaluated and weighed and a judgment to be made.  The only sure way is to see the fracture.  CBCT does allow us to "see" the fracture in certain instances but not all.

CASE REPORT

The following case would be typically diagnosed as a root fracture due to the bone loss pattern in the crestal area and into the furcation area as well as a long, narrow 8mm perio pocket on the ML surface.  There is however, coronal leakage under the mesial margin which could be a source of re-contamination of the root canal.

CBCT shows a long, periodontal breakdown on the lingual surface of the MB root - typical of a VRF.  Axial view also show the narrow bone loss in the same area - suggestive of a VRF.

Closer look at the axial view shows what appears to be a separation of the palatal side of the MB root.  This is a VRF - seen clearly on CBCT.

Rotation of the image, giving a palatal view of #14, shows a horizontal fracture in the MB root.

With these radiographic findings as well as the clinical findings, a confident diagnosis of vertical root fracture can be made.  Extraction was recommended in this case.

9.5 Year Recall of Apicoectomy

Last post, talked about how apicoectomies can be used to save teeth and the periodontium - tissues whose form and function are never truly replaced by dental implants. As a follow up to that post, here's a 9.5 year recall on an apicoectomy.

 This patient has crowns on #6-#11.  Tooth #6 is causing a localized ache, affected by pressure and chewing. #6 is sensitive to percussion with normal probings. DX:  Prior RCT with Symptomatic Apical Periodontitis (SAP). The margins are suspicious, but apical surgery was chosen to address the infection without disturbing the existing crown.

Apicoectomy completed, no root fractures seen with microscope. MTA retrofill.

9.5 year recall.  Tooth is fully functional, asymptomatic with radiographic healing.  Apicoectomy has preserved the tooth and the periodontium for an extended period of time.

Apicoectomies Save Teeth

Endodontic surgery has an established record of success.  Modern materials and equipment (microsurgery) make it even more successful.

In a recent updated meta-analysis of the literature regarding endodontic surgery (Tsesis et. al.), a successful outcome of endodontic surgery was seen in 89% of patients at 1 year.  It also pointed out that modern materials and equipment (MTA and microscopes) are associated with better outcomes.

The following case shows the benefit of endodontic surgery, use of CBCT in surgical planning, and the surgical correction of endodontic overfill.

This root canal was done by her general dentist 3 months earlier.  As you can see it is overfilled, post placed, crown prepped and ready for new crown, but patient continues to have symptoms with the tooth.

CBCT taken to evaluate the root morphology. It is clear that this is a single root/canal.  (The canal has an oblong shape)  It was chosen to treat this tooth with apical surgery to preserve the restorative work that has been completed and assure that the overextened gutta percha is removed.

Apicoectomy completed with MTA retrofill.

9 month recall show complete healing of the periapical lesion, tooth is fully functional and asymptomatic.  This procedure saves the patient significant time and money over extraction and implant placement.

SOURCES:

Outcomes of Surgical Endodontic Treatment Performed by a Modern Technique: An Updated Meta-analysis of the Literature
Igor Tsesis, Eyal Rosen, Silvio Taschieri, Yoel Telishevsky Strauss, Valentina Ceresoli, Massimo Del Fabbro

Journal of endodontics 1 March 2013 (volume 39 issue 3 Pages 332-339 DOI: 10.1016/j.joen.2012.11.044) 

Teeth & Dental Implants: Not the Same

At the recent AAE Convention, Dr. Hessam Nowzari presented a lecture on implant outcomes.  Dr. Nowzari is a diplomate of the American Board of Periodontology and the former director of advanced periodontics at USC from 1995 to 2012.

Dr. Nowzari discussed the difference between the tooth and an implant from a unique perspective. Often left out of the discussion regarding implants is the importance of the periodontium and how loss of the the periodontium (tooth, periodontal ligament, dental papilla, supracrestal fibers, lamina dura) affects the remaining gingival esthetics, including the esthetics around the dental implant.

It is well known that anterior gingival esthetics around an implant are one of the most challenging parts of implant dentistry.  The reason this is so challenging, is that the natural periodontal tissues (see image) that give the gingiva it's phenotype (appearance) are gone.  An implant's best chance at "natural-looking" gingiva/papilla is a natural tooth next door!  Dental papilla belong to teeth. 

While implants have an important part in dentistry, an implant can never effectively reform the periodontium.  The bundle bone and the family of fibers (dentogingival, dentoperiosteal, alveologingival, periosteogingival, interpapillary, intergingival, circular, semicircular, transgingival, intercircular, transeptal fibers) that create the architecture of the dental papilla all belong to the tooth.

This debate between implants and endodontics should not exist.  Implants and root canals are not alternative treatments.  If a tooth and its surrounding periodontium is in tact, we should make every effort to preserve them, because an implant cannot restore these periodontal tissues and loss of these tissues leads to a host of other challenges.

 Dr. Nowzari hosts a periodontal & implant symposium that may be one of the few (if only) implant CE events that is not sponsored or underwritten with any commercial interest (also available for download).  It may also be the only of its type where endodontists and implant surgeons are participate together.  We would highly recommend you check it out.

Successful Endodontics in Your General Practice

Successful endodontic treatment in the general dentist's office is based upon proper case selection.

Proper case selection will allow endodontics to be a profitable, enjoyable procedure and provide a valuable service to your patients that will build your practice.

Failure to perform proper case selection will result in:

1. Frustration

2. Loss of patient confidence

3. Loss of practice revenue

4. Additional costs incurred with retreatment or repair of iatrogenic damage

The American Association of Endodontists has prepared an assessment form to help clinicians evaluate the level of difficulty associated with endodontic treatment to help the clinician decide when to refer. (click here)

To summarize this assessment form, here's a breakdown of the type of cases that are considered minimal, moderate and high difficulty level.

MINIMAL DIFFICULTY

1. Pt is healthy, cooperative, minimal pain and/or swelling

2. Diagnostics are clear and pulpal/peripaical diagnosis made without complication

3. Tooth is easily accessible for treatment. (anteriors/premolars w/ slight inclination or rotation)

4. Canal is open, not calcified, mature apex, no resorption

5. No previous RCT

6. Root has slight curvature

7. Periodontium is healthy

MODERATE DIFFICULTY

1. Pt has minimal health issues, anxious - but cooperative, moderate pain and/or swelling

2. Diagnostics requiring additional evaluation (sinuses, TMD, electric pulp testing on calcified teeth)

3. Tooth accessibility is difficult - 1st molars, moderate inclination, rotation, crown, bridge, extensive decay

4. Canal is reduced in size, pulp stones, wide apex

5. Prior RCT without complication

6. Root has moderate curvature

7. Moderate periodontal disease

HIGH DIFFICULTY

1. Complex health issues, difficulty cooperating, severe pain and/or swelling

2. Diagnostics difficult - confusing complex signs & symptoms, chronic oro-facial pain

3. Tooth accessibility is difficult - 2nd & 3rd molars, severe inclination, severe rotation, crown/bridges with alignment irregularities

4. Canal is calcified (not visible), S or C-shaped, canal divides in middle or apical thirds, additional roots (3 rooted bicuspid), apex is open

5. Prior RCT with complication

6. Root has severe curvature

7.History of traumatic injury (avulsion, horizontal fracture, luxation)

Each clinician must evaluate the difficulty level and select cases that match his/her skill level and cases for which they have adequate instrumentation.  Pick cases that you can do in a timely manner, without complications.  As you become more and more comfortable, select slightly more difficult cases to challenge you, always being aware of that some cases are better managed under the microscope and with the aid of CBCT.

 

 The following case demonstrates the benefit of proper case selection.

Root Canal on a C-shaped, 2nd molar, through a crown with mild angulation and calcified canals makes this root canal a "HIGH DIFFICULTY" level.  The clinician performing this treatment had challenges due to these issues.  Access was difficult, interpreting the c-shaped canal was difficult and C-shaped canal all led to the mesial perforation.  The calcified canals also made it difficult to instrument/fill to the apex.  The perforation was improperly managed by sealing with gutta percha and patient was not informed of the complication.

CBCT view of the issues

Retreatment completed with MTA repair of mesial perforation.

  Prognosis: Fair

Proper case selection also helps you to build relationships with your endodontist.  When you have a good working relationship with your endodontist, you can rely on him/her to help you advance your endodontic skills and experience as well as help in difficult case management.

Missed Canals Cause Root Canal Failure

Endodontic therapy has a well documented rate of success.  There are situations where initial endodontic therapy fails.  In a previous post, we discussed the role of bacteria in root canal failure despite the separation of a rotary instrument.

Root canal failure, as well as failure of any dental treatment, is often associated with bacteria. Bacteria that is incompletely removed from the canal system during endodontic treatment will cause root canal failure. Unfortunately, sometimes that failure is not identified until months or years later and then some people condemn root canal therapy as unsuccessful, when the cause may be incomplete root canal therapy leaving bacteria behind in the canals.

The following example is a root canal that was done 13 months ago by an associate dentist in a general dental practice.  This can sometimes create a difficult situation for the owner dentist, when the patient returns with an abscess a year later.

Root canal done 13 months earlier.  Large periapical lesion on mesial root.  Short root canal filling on mesial canals.  The prognosis for this tooth was poor at the time of completion because the MB canal was not cleaned and obturated. Bacterial left behind will continue to cause periapical disease.

CBCT shows missed MB canal and short ML canal filling.

Missed MB canal located immediately with microscope.

All canals cleaned and shaped.  This tooth now has good prognosis for success.

As mentioned, bacteria left behind will cause failure of root canal treatment.  Root canal failure is most often caused by failure to completely remove bacteria from the canal system or failure to seal out bacteria from re-entering the canal system.

CBCT as Aid In Removal of Separated File

Removal of a separated instrument is rarely a simple task.  The closer to the apex, the more difficult the removal.  In this case, tooth #19 had a separated instrument 6 yrs earlier. The tooth had become symptomatic and the patient was having extensive crown and bridge work done.

A CBCT was taken to evaluate the separation in 3D.  This image was very helpful because it told us the anatomy of the mesial root. It shows clearly that the mesial root is a single root, rather than two separate roots.  With this information, we can plan to remove some tooth structure between the MB and ML canals in our attempt to access and remove the separated instrument.  It also showed us that there were 2 separated instruments in the MB canal.  This information is crucial in our ability to remove the spearated instrument. (The radiographic imaging also warned us not to remove any dentin mesial to the prepared space to prevent root perforation)

This treatment can only be accomplished with the use of the dental operating microscope and use the of ultrasonic instrumentation.  Approximately 1 hour of treatment time was used in removing the separated instruments.

2 separated instruments

Final obturation.

Take home message from this case...

Always easier to prevent a separation than remove a separation.

Patients should be informed if an instrument separation occurs.

Advanced imaging (CBCT) provides valuable information that affects the course of treatment.

Microscopes are an indispensable tool in modern endodontic therapy.

Remembering James H.S. Simon DDS (1934-2013)

On Sunday, Feb 3, 2013, Dr. James H.S. Simon passed away. Dr. Simon was one of the pioneers of modern endodontics.  He dedicated his career to education and was truly an amazing teacher, mentor and friend.  I'm grateful for my association with Jim and the things he taught me about endodontics.

Dr. Simon (Chief) and his posse at Jackson Hole, WY - Oct 2012 meeting of American College of Endodontists.

The following bio was provided by Dr. Ilan Rotstein of USC.

 

Dr. Simon was born in 1934 in Boston. Between the ages of 14-18 he attended the Phillips Exeter Academy in New Hampshire, known for its excellence in education, and graduated from the Academy in 1953. Between the ages of 18-22 Dr. Simon attended Bowdoin College in Brunswick, Maine, where he majored in biology. He spent the next 4 years in Temple University School of Dentistry in Philadelphia obtaining his D.D.S degree. Following dental school Dr. Simon spent 2 years at Boston University School of Medicine where he studied oral pathology and endodontics with Henry Goldman, Kurt Thoma and Herb Schilder and received his certificate in endodontics. For the next 3 years he was engaged in a private practice in Quincy, Massachucetts, where he limited his practice to endodontics. After 3 years of private practice, Dr. Simon joined the Veteran’s Administration in White River, Vermont, treating endodontic cases and in addition serving as a research associate at Dartmouth Medical School in Hanover, New Hampshire.

In 1968 Dr. Simon joined the VA Medical Center in Long Beach, California, in order to start the first endodontic residency program there. For the next 32 years, Dr. Simon was the Director of the Endodontic Residency Program at the VA Long Beach where he mentored and trained more than 60 residents. This period of 32 years was the longest full-time teaching program under one director in the nation. During that period, Dr. Simon also held a part-time teaching position at USC School of Dentistry where he taught together with Al Frank, Dudley Glick, John Ingle and others. In 1974, he joined the faculty at Loma Linda School of Dentistry as part-time faculty. In July 2001, Dr. Simon was recruited to USC where he served as Professor of Clinical Dentistry and Director of the Advance Endodontics program. During that time he mentored and trained more than 110 advance endodontic students.

Dr. Simon was a Diplomate of the American Board of Endodontics, President of the College of Diplomates of the American Board of Endodontics, Director and President of the American Board of Endodontics, Fellow of the American College of Dentists and

Fellow of the International College of Dentists. He was member of many prestigious dental organizations and held leadership positions in the American Association of Endodontists. Dr. Simon published extensively in the dental and endodontic literature and in 2005 he received the Louis I. Grossman Award by the American Association of Endodontists. This most prestigious award is given to an author for cumulative publication of significant research studies that have made an extraordinary contribution to endodontics. Dr. Simon was an international authority in the field of endodontics and used to lecture extensively at universities and professional meetings in the United States and throughout the world.

Jim is survived by Helen, his wife of 53 years, his children Jeffrey, Linda and David, and his grandchildren Alexis, Morgan, Jake, Jordan and Jason.

Bacteria Cause Root Canal Failure - Not Separated Instruments

Bacteria are the main cause of endodontic infection and endodontic failure.  If we can remove the bacteria and prevent its re-entry into the canal space, then we can expect success.  Separation of an endodontic instrument does not cause root canal failure, rather the incomplete removal of bacterial causes endodontic failure.  The follow case demonstrates this very clearly. File separation occurred with initial endodontic treatment. The separated file prevented complete cleaning and shaping of the canal.  Upon retreatment, the separated file was not removed, but rather pushed apically. However, the canal was cleaned, shaped and filled to the apex with the separated instrument left in the tooth.  The periapical lesion healed and the tooth is asymptomatic and functional.  I often explain to patients that a separated instrument is not a big problem, unless it prevents us from completely cleaning and shaping the canal.

Prior RCT w/ apical lesion. Small file separation preventing complete shaping and cleaning.

Separated file pushed apically and not retrievable.

Complete cleaning and obturation to the apex. Separated file at the apex.

Removal of bacteria has led to complete healing despite the presence of the separated instrument.

Lateral Portals of Exit

As clinician readers know, the canal anatomy of teeth is rarely simple. Lateral portal of exits (lateral canals) are a significant challenge to clean and are present in many of the teeth we see for root canal therapy. In a previous post, I discussed the use supplemental irrigation and ultrasonic instrumentation to clean isthmus tissue. That post can be found here: http://www.theendoblog.com/2012/07/the-isthmus.html I use these same techniques to address lateral portal of exits. These lateral exits are very common, but with proper irrigation, they can be predictably addressed.

Sometimes, as in this #19 below, the exit can be found at the apex in the form of a sharp distal turn or delta. Direct instrumentation may or may not be possible with small, pre-bent files (6 or 8).

These exits can also be found in the furcation region. If untreated and contaminated with bacteria, they can feed furcation radiolucencies and cause attachment loss (probing). Here is a straightforward #30.

 

 

Untreated, you will see radiolucencies centered on the exit as in this #9 retreated below. I measured to the depth of the lateral canal and focused my irrigation and irrigant activation at that level.

 

 

 

 

Always be aware that the potential for more anatomy exits. With this #28, I found 3 canals splitting at midroot and thought I had found all the anatomy. Fortunately, extensive irrigant activation picked up a lateral exit off the mesial buccal canal in the apical third. Tooth #29 is scheduled for retreatment.

 

In summary, do not believe for a second that sticking a file in a canal completely cleans a canal system.

 

Merry Christmas!

 

Justin Parente

Alpharetta Endodontics

www.Alpharettaendo.com

www.facebook.com/alpharettaendo