Using CBCT to Diagnose the Depth of a Cracked Tooth

 One of the many uses of CBCT is to help us determine the depth of a crack - seen on the occlusal surface of a tooth, but uncertain as to how deep it goes down the root.  Obviously the deeper the crack goes below the CEJ, the poorer the long term prognosis.

This patient was mostly asymptomatic until he recently bit into something and has had pain ever since.

Periapical film

2 Cracks seen on the MMR - with staining

CBCT shows a narrow, bony defect identifying a crack in the axial (Z) view.  The sagittal (Y) view shows the depth of the crack.  A new crown would have to go past this depth to cover the crack up.  This view helps us make a determination of the restorability of the tooth.

In this case, the crack would never be completed removed or covered up by the crown making the long term prognosis poor.  CBCT allows us to make this evaluation without having to remove the amalgam filling and chase the crack - saving the patient (and us) time and money.

Dental Computed Tomography (CBCT) to Identify Dental Sources of Maxillary Sinusitis

CBCT by J. Morita Veraviewepocs 3De

As endodontists, the use of CBCT (Cone Beam Computed Tomography) has allowed us to cross this barrier and diagnose dental pathology which is adversely affecting the maxillary sinuses.  These images also allow us to communicate more effectively with patients and physicians who are trying to manage and treat these chronic sinus issues.  In order for dental and medical specialists to work together, new paths of communication must be developed.  CBCT (3D imaging) is helpful in bridging the communication gap between dentistry and medicine.

The following cases demonstrate the usefulness of CBCT in identifying odontogenic sources of chronic sinusitis.  Several radiographic findings are pointed out which help identify odontogenic sources for chronic sinusitis.  These common findings seen with high resolution CT imaging include:

1. Perforation of the floor of the Mx sinus
2. "Halo effect" elevation of the floor of the Mx sinus
3. Thickening of sinus membrane adjacent to odontogenic infection
4. Air bubbles in the sinus suggested of an acute sinusitis

CBCT for DIAGNOSIS
CBCT (J. Morita Veraviewepocs 3De) demonstrates a large periapical radiolucency around the buccal roots of #15.  The sagittal view shows elevation in the floor of the sinus (halo effect).  Coronal view shows arrow pointing to a missed mesio-buccal canal causing the endodontic infection. Air bubbles seen in the maxillary sinus are indicative of an acute sinusitis. Endodontic retreatment is required BEFORE sinus treatment.  Failure to address the odontogenic source of the sinus infection will result in recurrent sinus infections.

CBCT for DIAGNOSIS
CBCT (J. Morita Veraviewepocs 3De) demonstrates a large periapical radiolucency around the mesio-buccal root.  The sagittal and coronal views both show elevation in the floor of the sinus (halo effect) as well as perforation of the floor of the sinus.  Endodontic treatment is required BEFORE sinus treatment.  Failure to address the odontogenic source of the sinus infection will result in recurrent sinus infections.

CBCT for DIAGNOSIS
CBCT (J. Morita Veraviewepocs 3De) demonstrates a large periapical radiolucency around the buccal roots of #3.  The sagittal and coronal views both show elevation in the floor of the sinus (halo effect) as well as perforation of the floor of the sinus.  Endodontic treatment is required BEFORE sinus treatment.  Failure to address the odontogenic source of the sinus infection will result in recurrent sinus infections.

Fortunately, these high definition images also identify the problems with previous endodontic treatment and the solutions to remove the odontogenic source of infection.  These common endodontic findings include:

1. Missed (untreated) canals in a previously treated root canal
2. Short filled canals in a previously treated root canal
3. Iatrogenic damage in a previously treated root canal

Proper endodontic treatment of the dental infection is the first step in addressing the chronic sinusitis of odontogenic origen.  If sinus symptoms persist, following endodontic treatment, then referral to ENT is recommended.

CBCT in Endodontics to Treat Difficult Anatomy & Preserve Teeth

A patient recently came to SSE for a second opinion. She had a root canal on #21 just a month earlier by an endodontist.  After the root canal, she continued to have pain and the root canal was retreated shortly thereafter.  The patient was then sent to a periodontist who recommended extraction and placement of an implant.  Aware of endodontic surgical options, her general dentist recommended she come for an additional evaluation.  The patient was highly motivated to save her natural tooth.

Our exam found #21 normal to percussion, normal probings and swelling on the buccal.  An additional canal was suspected, so CBCT was taken for further review.

CBCT clearly shows an additional lingual canal.  CBCT mapping allowed us to determine where the canal would be located and confirm that it had its own apical foramen.  With greater understanding of the canal anatomy, available only through 3D imaging, we recommended non-surgical retreatment to address the missed lingual canal.

With the aid of the microscope, we were able to locate and treat the missed lingual canal.

Because a canal was missed, retreatment (rather than apicoectomy) was the treatment recommended. Prognosis is good. Proper endodontic therapy will save this patient time and money.  Fortunately, this patient's dentist suggested a second consultation for endodontic surgery rather than the extraction and implant placement. Endodontists are specialist is saving teeth.

Do We Really Need a Cone Beam Scan?

A recently published article discussed the widespread acceptance of dental implants, and the pressure upon general dentists to provide these dental services to their patients.  CBCT is marketed as the solution to remove the barriers that stop many general dentists from placing implants in their practice.  The article then went on to discuss the reasons why CBCT is often overused and its popularity is fueled by misinformation regarding its necessity, safety and efficacy.  While this argument was made regarding use of CBCT for placement of dental implants, the same argument could be made against the use of CBCT in endodontics.

Some of the points argued against the use of CBCT are as follows:

• Risks of ionizing radiation include cancer, burns & other injuries
• Dentists can order CT scans at any frequency with no regard to patient's prior radiation exposure
• Dental offices with CBCT are seven times more likely to prescribe a CBCT scan compared to those offices without CBCT
• CBCT scans are too expensive for the average patient
• Poor ROI (return on investment) for a small dental practice with CBCT
• CBCT scanner require additional office space
• CT may soon require additional registration and documentation

While each of these points of argument may have some validity, the counter argument would be:

• Not all CBCT scans are the same (click here).  Focused field, low dose radiation scans are available which limits the amount of radiation.  CBCT is a fraction of the radiation compared with conventional medical CT's.
• CBCT can prevent a host of complications that can cause short and long term problems
• CBCT can reduce the cost of treatment by preventing complications and the need for treatment revision
• Dentists without access or experience with CBCT are less likely to understand and appreciate all the potential applications/benefits of 3D imaging
• Dentists are expected everyday to put their patient's best interest first over any financial benefit.

In my opinion, in regards to endodontics, CBCT will be required to provide the highest levels of care.  Just as a microscope improves the quality of care, CBCT improves the imaging providing a higher level of endodontic care.

I think the only way to appreciate the benefit of 3D imaging over traditional 2D imaging is to see it.

The following videos are an attempt to show how CBCT imaging provides valuable information that improves diagnosis and treatment in endodontics.  The videos are made with a screen capture software. I did notice that the video recording of the screen is a little jumpy. Hopefully you'll get the idea...

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.

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) 

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.

Apexification using Pulpal Regeneration - 2 Yr Results

At Superstition Springs Endodontics, we are leaders in novel endodontic treatments including pulpal regeneration. The traditional treatment for immature roots of CaOH apexification fails to strengthen the root of the tooth and leaves the root more prone to fracture over the lifespan of the tooth. 

Pulpal regeneration allows "pulp-like" tissue to re-grow into the immature root and continue the development of the root. This provides the root with stronger, thicker root walls. Here's another successful case of pulpal regeneration.

 

This young patient had a traumatic incident to tooth #9 5 months earlier. At our initial evaluation, the tooth responded normal to thermal testing. We decided to monitor the tooth over time. At a follow up visit, #9 exhibited no response to thermal testing with an open apex.

Pulpal regeneration was started. Complete pulpectomy was performed with minimal instrumentation to the apex, and irrigation with 5.25% NaOCl. A blood clot was initiated into the canal, a collagen plug was placed and an (white) MTA coronal barrier was placed below the level of the CEJ.

At six month recall, the tooth is asymptomic and functional. The radiograph shows dentinal bridging apical to the MTA placed intracoronally.

 

A sagittal view using CBCT also clearly shows the dentinal bridging below the MTA plug.

At the 2 yr recall of #9, the tooth is asymptomatic, fully functional and orthodontic treatment has been completed.

CBCT Reveals Root Resorption Unseen in Regular Radiography

The following case shows the advantage of CBCT in endodontic diagnosis.


The following patient returned to our office today for re-evaluation of #14. We previously looked at #14 which had some gingival swelling, yet we could not definitively diagnose the tooth as necrotic. We assumed the swelling was a periodontal abscess and had given him an antibiotic. He returned reporting no relief with the antibiotic and short, spontaneous episodes of severe pain. Once again our diagnostics were inconclusive. Normal to palpation, normal to percussion, normal to probing, responsive to cold on the lingual and unresponsive on the buccal, normal response to EPT. The canals were obviously calcified and the pdl looked normal around the roots. We decided we would take a CBCT to see if we could see any additional radiographic changes.

The CBCT clearly shows a resorptive defect on the palatal. The CBCT also tells us the location (mesio-palatal), the size of the defect which allows us to make a restorative call.

Look again at the initial film. There is no sign of this resorption with traditional 2D imaging. CBCT continues to surprise me.

Use of CBCT to Detect Small Apical Lesions & Length Determination in Endodontics

Two recents studies published highlight some of potential applications of CBCT in endodontics.

The first study by Tsai et. al. supports our clinical experience with CBCT, that it is more effective than traditional periapical films at detecting small lesions.

This study was designed to test the effectiveness of CBCT in detecting very small apical lesions created using small burs on human cadavers. It also compared the Kodak 9000 3D (now called Carestream with the demise of Kodak) and the J. Morita Veraviewepocs 3De. This study showed that both CBCT units were fair-good at detecting simulated lesions with a diameter between 0.8-1.4mm and excellent accuracy with simulated lesion >1.4mm diameter. Traditional periapical films were poor at best, in detecting lesions of these sizes. Another interesting find in this study was that there was no statistically significant difference between the two CBCT units evaluated. These two CBCT units are by far the most common in use by endodontists because of there focused field size, lower radiation dosage and high resolution.

The second study by Jeger et. al. indicate that CBCT may be an effective tool for measuring working length in anterior teeth compared to electronic apex locators. The patients in this study had previously received a CBCT and then required endodontic treatment on an anterior tooth included in the scan. The root canal length was measured by an endodontist using an apex locator. This length was compared with a measurement taken from the CBCT in a vestibulo-oral and mesio-distal CBCT slices by an examiner not involved in the endodontic treatment.

The Pearson correlation coefficient (r) comparing the the CBCT measurements with the apex locator was 0.97. The CBCT also showed higher intrarater reliability 0.99.

With the incorporation of CBCT into our practice of endodontics at Superstition Springs Endodontics, we have found many uses for CBCT that we did not initially plan on. Length determination using CBCT prior to treatment is just another potential application of CBCT in endodontics.

For a clinical example, let me share one of my cases that demonstrates both of these applications.

Tooth #29 has what looks like a fairly normal pdl. Whild some condensing osteitis is noted, without symptoms, I would consider this WNL.

CBCT clearly show periapical lesion on #29 with cortical plates in tact. A clear example of ability of CBCT to show more accurately the minor changes in the bone.

With this added radiographic evidence, the tooth was diagnosed as necrotic pulp and endodontic treatment was completed. My working length was 20.0mm.

After completion of RCT, I went back to CBCT and measured length, from coronal height to radiographic apex in a coronal and sagittal views. The length determined by CBCT was 20.5mm and my working length as determined by Root ZX - 0.5 mm short of apex - was 20.0mm.

This particular case shows the ability of CBCT to help detect small lesions and determine working length.

CBCT is the future of endodontics!

Sources:

Tsai P, Torabinajad M, Rice D, Azevedo B. "Accuracy of Cone-Beam Computed Tomagraphy and Periapical Radiography in Detecting Small Peripaical Lesions". JOE 2012, 38:7, p 965-970.

Jeger F.B., Janner S.F.M., Bornstein M.M., Lussi, A. "Endodontic Working Length Measurement with Preexisting Cone-Beam Computed Tomography Scanning: A Prospective, Controlled Clinical Study". JOE 2012, 38:7, p 884-888.

Cone Beam CT in Endodontic Diagnosis

Cone Beam Computed Tomography (CBCT) is a valuable radiographic tool in endodontic diagnosis. With traditional 2D radiography, you see only a coronal view. Historically in endodontics, we have taken the shift shots to try and give us an "angled" view of the tooth. Remember the rule of SLOB?

With CBCT, you can evaluate the tooth from sagittal, coronal & axial views. You also have a volume of data that can be manipulated by the computer to rotate the tooth 360 degrees and look at the tooth from any angle. The longer I use this technology, the more convinced I become of its importance and value.

The following case demonstrates the benefit of CBCT in endodontic diagnosis.

This patient presented to Superstition Springs Endodontics with chief complaint of "pressure to biting and sensitive to brushing". Root canals on #14 and #15 were done approximately 10 years ago.

Our exam found mild palpation tenderness over #14 and #15. Both teeth were percussion sensitive and perio probings were normal. A large pa lesion was noted on the palatal root of #14, but since #15 was also so symptomatic, we decided to take a CBCT for more detailed radiographic exam.

This CBCT slice through #14 shows the extent of the pa lesion on the palatal root. It also shows the elevation of the floor of the sinus and the thickened adjacent sinus membrane. This appears to be a sinusitis of dental origin.

This CBCT slice through #15 shows a definite pa lesion on the MB root of #15. This also exhibits a halo effect. This image confirms the diagnosis of Symptomatic Apical Periodontitis on #15. Without this image, I would have recommended initiating treatment on #14 only. This image allows us to make a more confident diagnosis on #15 and treat both teeth simultaneously.

As an interesting side note, an inverted, impacted wisdom tooth is noted. This made the original radiograph difficult to read and see the MB lesion.

At Superstition Springs Endodontics, we are leaders in the use of CBCT in endodontics.

Finding Missed Canals Using Cone Beam Computed Tomography (CBCT)

We have had lots of discussion regarding the use of CBCT in endodontic diagnosis and treatment planning. CBCT is the future of endodontics. 3D imaging as an adjunct to 2D imaging is superior to 2D imaging alone. The ability to evaluate a tooth in a sagittal and axial plane (in additional to the traditional coronal view of standard radiographs) provides valuable information that will lead to the preservation of teeth by improved endodontic treatment, endodontic retreatment and endodontic surgery.

There will be many who think this statement is over the top. However, I would compare the advent of focus-field, high resolution CBCT to the introduction of the operating microscope in endodontics. While there was initial resistance to adoption of the microscope, and still some continued resistance by a few in our specialty, the microscope has undoubtedly improved the quality of endodontic care. CBCT is the same. There will be some who argue that they don't need it, however, it undoubtedly will improve the quality of endodontic care and help preserve teeth.

As an example of the benefits of CBCT in improving endodontic diagnostics and treatment, I present the follow 4 cases. Each case completed by a different endodontist. All of these clinicians are highly skilled endodontists using microscopes. However, in each case, canals were missed and the patient continued to have issues. They have different stories, but all ended up in our office for an evaluation or second opinion. I have included myself as one of these 4 endodontists. (One of the cases is my own)

CASE #1

#31 is the symptomatic tooth. Two canals have been filled to a good length.

CBCT slice of mesial root shows the two mesial canals join and exit at one apex.

This is another slice of mesial roots showing the buccal filling and the ML missed canal. The sagittal view tells us where to look when we retreat this tooth. Axial view also demonstrates the missed canal. Using these two views, when I retreat this tooth, I will know where to explore without perforating the root.

This particular endodontist refunded the patient and preferred that we retreat the tooth at our office.

CASE #2

This root canal was treated by another endodontist and then retreated after symptoms failed to resolve. She came to Superstition Springs Endodontics for a second opinion. The obturated roots look filled to an ideal length.

CBCT reveals a missed MB#2 canal. Blue outline shows an axial slice of the MB root. The pear-shaped root outline reveals the missed canal.

The sagittal view also shows the MB#1 canal is off center of the long axis of the root. A lesion into the sinus cavity is noted. Note the distinct MB lesion visible in the CBCT. I explained to the patient that it would be the other endodontist would likely retreat this tooth at no charge, but this patient has elected to retreat the tooth in our office.

CASE #3

This root canal done in 2007. Recently became symptomatic.

CBCT shows lesion on MB and DB with elevation of floor of sinus. This corresponds to chronic sinus issue patient has been dealing with.

Cross sectional slice (axial) through the MB root shows the missed MB#2 canal. The pear-shaped or figure-8 shape of the MB root reveals the missed MB#2 canal.

This sagittal view shows that the missed MB#2 canal is actually a separate root. While the roots are fused all the way down, it has its own apex.

The CBCT is a map for retreatment. It tells us exactly where to look to find the missing canal.

This patient returned to her previous endodontist for retreatment.

I know each one of these endodontists, and they all do excellent work. I confidently suggested to each of these patients that they return to their previous endodontist for evaluation. Using the CBCT map for retreatment, I am confident each one of these endodontists will find the additional canal. One endodontist is retreating at no charge, one endodontist is refunding patient and she will have treatment in our office, and the third patient did not want to return and has elected to pay for retreatment in our office.

CASE #4 - My Missed Canal Found with CBCT

I completed this RCT in Nov 2011. Palatal lesion seemed to improve, but patient symptoms returned. In this particular case, I found only 2 canals. After extensive searching under the microscope, I determined that this must be one of those tricky 2 rooted Mx molars. Since symptoms returned, we took CBCT to see if I missed anything.

CBCT reveals that I did miss a DB canal. However, looking closely at the axial view, my assumption that this is a 2 rooted molar was correct. The palatal and DB roots were fused as one. Sagittal view shows the missed DB canal. Axial view shows the missed DB as well. The CBCT is now a map for retreatment.

As explained, the axial and sagittal view provided by CBCT is invaluable. More information provides for better treatment. This post should demonstrate the level of complexity of molar endodontic therapy even with the use of the operating microscope and the benefit of 3D imaging over 2D imaging alone.