One thing in endodontics that isn’t fixable (most of the time) is a vertical root fracture. Two common signs that are associated with vertical root fractures are a “J-shaped” radiolucency, and a deep periodontal probing in the area. These are clues that a VRF may be present, but they are not pathognomonic of a VRF. Since a VRF usually dooms a tooth for extraction, it is critical to arrive at the correct diagnosis.
This first case was referred to Dr. Boehne for a second opinion by her friend. The patient was told by an endodontist that the tooth had a vertical root fracture and needed to be extracted. Tooth # 30 was a root canal treated tooth with periodontal probings extending to the apex and a classic J-shaped periradicular lucency. Initially, endodontic disassembly was performed so that the internal root structure could be examined through the surgical operating microscope. No fractures were visible. Although a fracture could not be viewed through the microscope, it didn’t rule out the possibility of an apical VRF, beyond the line of sight. To get a better understanding of the prognosis, this tooth was cleaned out three times over three months. The case was not filled until the periodontal probing returned to normal and radiographic signs of osteogenesis were present. At the three month recall healing is almost complete.
The second case (below) did not have a previous RCT, but still presented with a J-shaped radiolucency and periodontal probing to the apex. This patient was worried that her tooth would have to be extracted. This tooth was treated in a single visit while the patient was visiting home from college. EndoVac irrigation technology was utilized as part of the treatment protocol. The recall shows how root canal therapy was successful at preserving the patient’s natural tooth.
When completing root canal therapy it is important to clean the canals to their apical terminations. Severe apical curvatures can make this challenging. It is often difficult to follow the natural path of the curved canal without causing iatrogenic damage. If the canal path can be maintain, file separation is a significant risk. In this case, I was able to create a reproducible glide path with hand files prior to using rotary files in an alternating crown-down technique. ProTaper Next X2 files were taken to length in all four canals (even the U-turn in the MB), with a brand new file being used in each canal to minimize fracture risk resulting from accumulated cyclic fatigue. A stainless steel post was placed with the bonded composite buildup, and I was able to prepare the subgingival distal crown margin under the microscope for the referring dentist.
Premolars often have wild anatomical variations in their pulpal anatomy. Not only do we need to locate and adequately clean this anatomy for successful treatment, but we need to do so without needlessly weakening the tooth. Premolars will often branch from one to two or three canals. When they do this in a single-rooted tooth, there will often be deep concavities on the external root surface. These concavities mean that the dentinal walls surrounding the canals are thin in this area, and strip perforations are very common when “standardized” shaping techniques are used.
Pre-operative CBCT evaluation can be used to identify these risky cases, and root-form appropriate cleaning and shaping techniques can be used to conservatively locate the secondary anatomy and avoid iatrogenic errors.
I treated this tooth in November of 2011. Pt presented with class III mobility, with the chief complaint of being able to depress the tooth. This tooth was so loose that the patient felt that it would fall out. Initially, a periodontal probe could reach the apex of the tooth. At recall, we can see that osseous regeneration is complete (on the PA radiograph and CBCT images). Mobility and periodontal probings have both returned to normal.
Many teeth are needlessly taken out that are savable with endodontic treatment. Part of the problem is that we are conditioned to think that a certain look is an appropriate gauge for biologic success. A second reason is that dentists don’t feel comfortable treatment planning around complex cases, as the outcome is less predictable.
This patient presented with 9/10 pain from the apical periodontitis associated with the post perforation in the distal root. After the post was removed, canal negotiated and cleaned his symptoms completely resolved. In order to gain treatment planning predictability, the case was monitored (and re-cleaned) until bone-fill was evident. The 1.5-year recall shows complete healing (note regeneration of a continuous PDL space and lamina dura). Notice that the mesial roots were not negotiable on the re-treatment, but healing still occurred since the biology was treated, as opposed to the radiographic esthetics. This patient was very happy to predictably save his tooth.
On average, the minor foramen is 0.5 mm coronal to the major foramen, which is 0.5 mm from the radiographic apex (Kuttler 1955). Gutta percha cannot seal beyond the narrowest diameter of the root shape, or into a divergent apex(Weine 1975). Gutta percha beyond this point certainly won’t help, and although tolerated by tissues (Seltzer 1975), extruded filling material is associated with delay healing (Molven 2002). Cone Beam Computed Tomography can help to determine where the actual minor constriction is in relation to the radiographic apex. This way, treatment can be more precise than “filling” every case to the radiographic apex to achieve “the look”, and deleterious effects can be avoided. Note how in the case above, the pre-op PA does not indicate where the minor constriction is. The CBCT view shows that the minor constriction is 3.2 mm coronal to the radiographic apex. The case was filled to the minor constriction, and excellent healing is evident at the 1-year recall.
This case follows the premolar post below, and highlights the importance of treating complex endodontic anatomy. Leaving canal branches untreated can lead to endodontic failures. When retreating a case like this, it is beneficial to locate the missed anatomy. Shaping a tapered apical preparation will aid in the disinfection and obturation as well. Warm vertical compaction techniques help to obturate these spaces when the heat source can be carried down to 3mm from the canal terminus.
Below is another retreatment case, where the original RCT failed because apical anatomy was not addressed. It is an example of how CBCT helped to determine that an apical perforation had occurred, and the location of the actual canal. Again, failing to treat this complex apical anatomy contributed to the original treatment failure.
Every tooth is important. Some teeth may carry more weight than others. For example, the tooth in this case is the distal abutment for a three unit bridge, and the posterior left occlusion hinges on whether or not this tooth can be saved.
Treatment planning these case types can be challenging for the general dentist because the reported success rates for endodontic retreatment are lower than for initial treatment. Furthermore, this tooth has a 7mm probing depth and lateral radiolucency on the mesial surface of the mesial root. Combined with this tooth being a distal abutment, this tooth is highly suspicious of having a non-restorable vertical root fracture. The pre-operative prognosis is guarded.
The treatment planning options for this tooth include:
1. Endodontic retreatment, saving the existing bridge.
2. Extraction, without replacing the teeth, leaving no left molar occlusion.
3. Extraction, replacing occlusion with a removable partial denture.
4. Extraction, replacing with two implants, two implant crowns, and a new crown on # 20.
Obviously, the best option is to save the natural tooth with endodontic retreatment, assuming we can be assured of a favorable prognosis. This option is the least invasive, most functional, and a fraction of the cost of replacement with dental implants.
Treating teeth with a questionable prognosis in multiple visits allows us to evaluate healing prior to completing the case. Confirming that a case will heal prior to finishing takes the guesswork out of treatment planning around questionable teeth. For this case, we were able to confirm success by confirming that the perio probing depth healed to 3mm, and osseous regeneration has occured. Now, treatment planning is straight forward. The tooth has been saved, so we can retain the tooth and the existing bridge.
In my office, if we cannot save the tooth in question, we do not charge the patient for the treatment, thus eliminating the financial risk for the patient and referring doctor. There is no additional fee for this service.
This case illustrates how modern technology, modern techniques, and new materials can be used to save teeth that would have been slated for extraction in the past.
This patient presented with a previously root canal treated tooth with iatrogenic perforations and an untreated MB2 canal. It became symptomatic, with a chronic apical abscess.
Cone Beam Computed Tomography aided in locating two perforations in this tooth, that occurred during the original treatment. The first was a strip perforation in the MB1 canal into the furcation. The second perforation was in the palatal canal, and a gutta percha cone was extruded through the perforation. CBCT also helped to locate a previously untreated MB2 canal.
The surgical operating microscope allowed for visualization of the perforations and the MB2 canal during all phases of treatment.
Endovac negative pressure irrigation was used to clean and disinfect the perforations.
Mineral Trioxide Aggregate allowed for predictable repair of the perforations.
The patient was very happy to save her tooth from extraction!
Although the literature may show that there is no difference in treating cases in one vs. two visits, I almost always treat cases with symptomatic apical periodontitis in multiple visits. The main reason is for predictability: I can make sure that we are able to resolve the symptoms prior to finishing the case. A second reason is that we can use calcium hydroxide to help disinfect the root canal system. In the last few years, technological advancements in irrigation have been shown to increase the efficacy of irrigants at disinfecting canals. For patients who have difficulty tolerating dental treatment, the potential exists to treat these case types in a single visit.
Above is a two year recall of #12. The tooth initially presented with a necrotic pulp and an acute apical abscess (acute exacerbation of chronic apical periodontitis, or “Phoenix Abscess”), and a buccal space infection. EndoVac apical negative pressure irrigation was used and treatment was completed in one visit for this 82 year old. Note that the canal shapes are still conservative (30-06). A fiber post was bonded into each canal. The two year recall shows success, with resolution of the periapical radiolucency, and the return of the radiographic PDL space and lamina dura.
In this case, an indirect pulp cap was done by the patient’s dentist years ago, and recently became symptomatic. Clinical photo of the complex microvasculature in a vital coronal dental pulp. This # 30 had five canals, with the fifth being a mid-distal. Endovac apical negative pressure irrigation is useful even in this case type. Although the main canals were only shaped to a 20-07 and the mid-distal to a 20-04, the microcannula reached beyond where the distal canals merged and allowed for a high flow of irrigants through each canal, to effectively remove vital tissue from the anastamosis. Fiber post bonded in the DL canal.
Tooth #20 presented with previous RCT and persisting Symptomatic Apical Periodontitis. The periapical radiolucency is bi-lobed, suggesting two portals of exit. It is important to locate and clean complex anatomy in order to heal the disease. The location of the “lobes” of the lesion give the location of the anatomy away, as the POEs tend to be centered in each lesion. I almost always complete re-treatment cases in multiple visits, to utilize calcium hydroxide as an inter-appointment medicament. There have been a few recent studies suggesting a good efficacy of negative pressure irrigation (the Endovac) in aiding canal cleanliness, even in one visit. This was my fist case using the Endovac in a one-step re-treatment. The shape was finished at 40-08, which is bigger than I would shape it to today. After debriding the accessory canal and flowing high volumes of irritant to the apex, the two year recall shows an excellent result with complete regeneration of the periapical tissue.
Two year recall: “Strindberg” success.
Gemenated molars often have unique endodontic anatomy. The pulpal system in this tooth was confluent with the gemination.
Patients are always happy to save their natural teeth. Even many teeth with significant defects resulting from External Cervical Invasive Resorption (ECIR) can be predictably saved.
ECIR is a non-inflammatory resorptive process that can occur when clastic cells have access to dentin following damage to the cementum / PDL protective layers of the root. After clastic cells remove dentin, PDL-like tissues invade the tooth. These lesions may become large because incipient lesions are difficult to detect, owing to the fact that they initiate within the periodontium, so are sub-gingival. The process is not related to the pulp of the tooth. Many cases are detected once the resorption reaches the pulp however, when the pulp becomes subsequently infected with oral microorganisms through the resorptive defect. At that point, patients will experience the typical symptoms of irreversible pulpitis.
The case below is an example of an extensive ECIR defect on the palatal of # 15. The patient’s chief complaint was lingering sensitivity to cold. A surgical approach from the palatal was used to debride and restore the area of resorption. Root Canal Therapy was completed because the pulp had become secondarily infected. When the patient returned for her one year recall, she reported that her tooth and gums were completely asymptomatic and functional, and she expressed her appreciation to be able to save her natural tooth.
Much of the success of endodontic therapy is determined by the ability to remove pathogenic microorganisms from the root canal system. In most cases this can be accomplished through orthograde root canal therapy. When apical complexities that aren’t treatable from an occlusal approach harbor persisting microorganisms, they are often predictably treatable with a surgical approach. Second molars are often difficult to access surgically, which makes intentional extraction followed by root-end resection, retro-preparation, retrofill, and replantation a viable option.
The case below illustrates this case type. Endodontic retreatment was performed due to Symptomatic Apical Periodontitis. Patency was not achievable due to ledging / transportation from the initial treatment. Consequently, sysmptoms persisted following retreatment due to bacteria remaining in the apical anatomy. Rather than extracting the tooth and being left with an edentulous area or prosthetic implant, the root canal treatment was completed ex-vivo and the tooth was replanted back into it’s natural site.
One year recall shows complete osseous regeneration of the Apical Periodontitis lesion. This tooth is free of symptoms, without mobility and is completely functional. The patient was extremely happy to be able to keep her natural tooth.
Perforation of a tooth during access used to have a poor prognosis, and often led to the extraction of the affected tooth. Fortunately, with modern materials and techniques teeth with perforations can now be predictably saved.
This case was started by a dentist, using the classic access design from the palatal toward the facial. An iatrogenic perforation was created through the facial aspect of the cervical third of the root while searching for the calcified canal. The sagittal view of the cone beam image demonstrates how this orientation for access will inherently lead to this type of perforation. The sagittal view also shows how the more appropriate straight line access is right through the incisal edge.
This tooth was treated in two visits. The perforation was repaired with white MTA, a glass ionomer orifice barrier was placed, and sodium perborate was sealed in the access as a walking bleach technique. An access through the incisal edge in the direction of the long access of the root was used to locate and treat the calcified canal on the second visit.
When a coronally loose #10 K-file won’t slide the last couple of millimeters to patency, as seen in the WL radiograph, it is almost never due to an apically calcified canal. If a hard, abrupt impediment is felt, it will either be the outer wall of a curve or an apical split. DB roots of maxillary molars are notorious for apical dilacerations to the distal. In this case, the file is hitting against the outer wall of the apical curve in the WL radiograph. Patency was achieved with a pre-bent #6 K-file (UR rad, squint), and the shape was completed with hand files, including a pre-bent GT 20-06 rotary hand file. A pre-bent master cone was fit to length and obturation was completed.
This patient presented with Symptomatic Chronic Apical Periodontitis resulting from a necrotic tooth # 19. Our ability to resolve Apical Periodontitis is dependent on our ability to disinfect and seal all aspects of the root canal system. This tooth presented with severe calcification of both the mesio-buccal and mesio-lingual canals, which makes locating and treating these canals particularly challenging.
Root canal systems in mesial roots of lower molars are never straight. From the pulp chamber, going apically, the canals begin in the mesial direction and curve around to exit towards the distal in most cases. This curvature makes deep troughing for a patent lumen in a calcified canal risky. Since “drilling” is only possible in a straight line, any specific morphologic information obtainable is critical to decrease the chances of iatrogenic perforation or excessive gouging while attempting to locate canals by troughing deep into the root.
Further complicating this case type is the lack of anatomical landmarks. Natural extra-coronal landmarks are lost when prosthetic crowns are fabricated. The intra-pulpal dentin map becomes less useful as troughing continues further down a curved root.
In this case, both pre-operative and inter-operative CBCT scans were indispensable in locating the highly calcified mesial canals. Since the distal canal was easily located, it was used as a landmark to find the others. The distance and direction to look for the ML in relation to the D was determined using the CBCT axial view at the first appointment. After locating the ML, and troughing 4mm into the MB to no avail, CaOH2 was placed and an interoperative CBCT was taken. This scan was then used to find the MB canal in relation to the previously located canals and the area already troughed. The crown was removed and a provisional was fabricated during the first appointment.
This approach allowed for complete treatment of the root canal system. Importantly, the CBCT guided troughing allowed for a conservative removal of tooth structure to locate the calcified canals, which significantly increases the long term prognosis compared to blind drilling and gouging.
Although many text books will describe premolars as having one canal, anybody who practices endodontics will tell you that this is almost never the case. In fact, premolars can often be more difficult to treat than molars due to their anatomic variability and often skinny root and crown forms.
Maxillary second premolar root canal casts from Hess’ classic 1921 study:
Below are cases completed by Dr. Boehne demonstrating considerable variability in premolar anatomy. Note that the portals of exit in these cases range from one to eight. The number of canals are often variable within the same root as canals split and merge and re-split; note the 1:2:1:2 system in the upper right case. Root lengths and curvatures may differ vastly in the same tooth. Premolars commonly have apical bifurcations and even trifurcations and deltas. Contemporary endodontic techniques, and a lot of care, allow for the successful treatment of this challenging anatomy without the need for subsequent apical surgery.
The case below demonstrates a Root Canal Treatment that failed because the apical anatomy was not treated by the original treating dentist. Good osseous healing is evident at 10 months, after the apical bifurcation was addressed.
The Surgical Operating Microscope not only helps with locating and treating canals (primary endodontic anatomy), but it can also be a useful tool for locating and treating secondary endodontic anatomy. The case below demonstrates a deep apical bifurcation in the palatal root of # 2. This root was relatively straight, allowing for direct visualization of the bifurcation with the magnification and co-axial lighting provided by the SOM.
This 11yof had a traumatic fall, resulting in a complicated crown fracture on tooth # 9 and an uncomplicated fracture on # 24. One day of pulp exposure following the fracture caused Irreversible Pulpitis in # 9, and # 24 tested WNL to pulp sensibility testing. RCT was completed on # 9, and the tooth was restored with a fiber post and an esthetic bonded composite restoration. Tooth # 24 was restored with composite, and the occlusion was adjusted to light centric contacts without excursive interferences.
A “fast break” is a term used to describe a situation where a root canal disappears on a radiograph as you move apically. This happens when the main canal splits into multiple smaller canals that are not discernible on a radiograph. CBCT axial views are indispensable determining the number and location of these canals. Tooth # 13 (seen at the top of the CBCT axial view) branches into three canals. Note how a conservative access can be used to locate even multiple canals when their location is known prior to starting the case, significantly increasing the long term prognosis by preserving peri-cervical tooth structure.
The axial view of the CBCT image is extremely beneficial for determining the number of canals in a tooth. Even minor anatomy can be visualized on some cases. In this particular case, my assistant was able to identify the MB3 canal as the image loaded. Treatment of this tooth with a supernumerary canal was straight forward and predictable following pre-operative case assessment utilizing CBCT.
A “fast break” is a term used when a root canal seems to disappear on a radiograph as you move apically. It is often mistaken for a “calcification”, but in reality these are areas where the main canal bifurcates into multiple smaller canals that are too small to be discernable on a radiograph. CBCT can be useful to verify the location of this secondary anatomy. Note how on the PA, the canal is not discernable in the apical 2mm, whereas on the CBCT both apical canals are evident. CBCT technology facilitated the location, shaping, cleaning and filling of this complex anatomy.
A 31mm second molar with anatomy that makes both shaping and filling the root canal system a challenge.