The Lateral Puff in Endodontics: Clinically Significant or a Storyteller of Anatomy and Etiology? – A Case Report Series

by Mahmood Reza Kalantar Motamedi, DDS, MSc (Endo); Brett Gilbert, DDS, FICD, Diplomate, American Board of Endodontics

In modern endodontic practice, the focus has shifted from traditional cleaning, shaping, and filling methods to prioritizing conservative canal shaping first, opening the canals, and using advanced disinfection protocols with irrigation, enabling more effective cleaning before three-dimensional filling.1

To be more accurate and descriptive of root canal anatomy, it is recommended to use the term “root canal system” instead of simply referring to a “root canal.” The path from the coronal orifice to the apical terminus is not a straight and single route, and there are various accessory pathways throughout the system.2 Ramifications and accessory anatomy are found in different parts of the root, with 73.5% in the apical third, 11% in the middle third, and 15% in the coronal third.3

The root canal system’s complex structure makes it impossible for any known chemical or mechanical technique to sterilize it completely. Therefore, the treatment objective should be to remove biological tissues and reduce microbial contamination as much as possible, followed by the creation of an effective three-dimensional seal to encapsulate any remaining microorganisms.1

Lateral canals leading to portals of exit along the root surface at various locations serve as potential pathways for bacteria or their byproducts to reach the periodontal ligament (PDL) and cause disease. Similarly, bacteria from periodontal pockets can reach the pulp from the outside.4 Cleaning, disinfecting, and filling lateral canals and apical ramifications during treatment can be challenging and unpredictable. The clinical significance of sealing these lateral anatomical structures with sealer has long been a topic of debate among clinicians and researchers who ponder whether there is a correlation between the presence of a lateral canal filling with sealer and the overall healing of the accompanying peri-
radicular lesion.

Is It Necessary to Clean and Fill Lateral Canals?

The verification of the sealing of lateral canals and their portals of exit with sealer on imaging is a desirable objective of treatment by clinicians. The presence of the sealer in these spaces confirms that enough cleansing of the intracanal dentinal walls was accomplished during the root canal procedure. The only main significance of sealing these canal structures is when there is a chance that bacterial contamination from the inside of the canal system travels to the PDL, often resulting in a lateral lesion positioned at the portal of exit.4 However, clinical experience shows that lateral lesions can heal even without filling the lateral canals.4,5 A cadaver study by Barthel et al. reported no relationship between unfilled lateral canals and inflammation in the surrounding tissues.6

However, it must be stated that lateral canals and apical ramifications have been implicated with endodontic treatment failure when they are sufficiently large enough to harbour significant numbers of bacteria and provide these bacteria with unimpeded access to the peri-radicular tissues.4 Therefore, disinfecting these structures is important in cases of pulp necrosis and apical and/or lateral periodontitis. Efforts should be made to incorporate therapeutic strategies targeting these areas during disinfection.

In clinical practice, while filling lateral canals may not always be necessary for success, the presence of a filled lateral canal or lateral sealer puff on the final image can provide valuable confirmation that a lesion is a lesion of endodontic origin. This phenomenon indicates that the canal system walls have been debrided well enough to expose the lateral canal opening inside the root wall and allow the sealer to flow into and through the lateral canal portal of exit, reaching the lateral lesion. The presence of a sealed lateral canal can be valuable in terms of providing a more accurate prognosis for a given case. In essence, we can extrapolate that the sealer extrusion through the lateral canal to the coincident lesion serves as a storyteller to confirm a lesion is of endodontic origin and that sufficient cleaning was accomplished to allow sealer flow into this space.

This study presents some interesting case reports of lateral canals filled with a sealer extending into the lateral lesions. Our purpose is to show how these lateral canal fills and sealer puffs can tell a story about the pulp system anatomy and the etiology of lateral lesions and confirm the effective debridement and three-dimensional sealing of the root canal system.

Case Report 1

A 31-year-old male presented with a chronic abscess of tooth #18. Five years prior, Dr. Mehmood Motamedi (Dr. MM) performed primary root canal treatment on this tooth, but it presented with post-treatment disease. The coronal seal appears to be intact. There are no radiographic signs of periapical radiolucency or widening of the PDL (Fig. 1A). However, there is a buccal sinus tract that was traced with gutta-percha (GP) and extends towards the furcation (Fig. 1B). This raised the suspicion of a crack, but probing depths were within normal limits. After discussing this with the patient, it was decided that the patient should proceed with non-surgical orthograde retreatment. No crack was observed in the pulp chamber floor during the procedure, so treatment continued. The previous root-filling materials were removed, and 5% NaOCl was ultrasonically activated using UltraX (Eighteeth, Changzhou, China) to improve irrigation quality. The canals were then obturated using the warm vertical condensation technique and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). This case was completed in a single visit. Immediately after obturation, a lateral sealer puff was observed in the area previously traced with GP (Fig. 1C). This may indicate the origin of the endodontic lesion and the reason for the failure of the previous treatment. One-year post-operative radiograph shows a normal periapical appearance; the tooth is functional and asymptomatic (Fig. 1D).

Fig. 1A

 Case 1 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)
Case 1 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)

Fig. 1B

 Case 1 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)
Case 1 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)

Fig. 1C

 Case 1 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)
Case 1 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)

Fig. 1D

 Case 1 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)
Case 1 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)

Case Report 2

A 64-year-old female patient presented with pain in biting tooth #5. An enlarged apical lesion was noted extending coronally to the mid-root level on the distal (Fig 2A & 2B). The diagnosis for tooth #5 was pulp necrosis with symptomatic apical periodontitis. Root canal treatment was completed using rotary instruments to a final canal preparation size of 18/.04 in the buccal and palatal canals with ExactTaperHDC (SS White Dental, Lakewood, NJ). Copious irrigation with Triton (Brasseler USA, Savannah, GA) and activation with laser-assisted endodontic irrigation protocol using the EdgePro laser (EdgeEndo, Albuquerque, NM). Obturation with GP and BC Hi Flow sealer (Brasseler USA, Savannah, GA) using a single cone hydraulic condensation technique. A permanent access filling was placed. This case was completed in a single visit. Two exit portals are noted to be curving toward the distal aspect, and a third lateral portal of exit is visible more coronally and with a sealer fill (Fig 2C). The visual confirmation of the lateral canal portal of exit tells a story of anatomy and etiology, providing context and understanding as to the etiology of the large lesion as a manifestation of the intracanal pulpal necrosis extruding into the PDL space vial the lateral canal on the distal side of the root.

Fig. 2A

Case 2 by Dr. Brett E. Gilbert
Case 2 by Dr. Brett E. Gilbert

Fig. 2B

Case 2 by Dr. Brett E. Gilbert
Case 2 by Dr. Brett E. Gilbert

Fig. 2C

Case 2 by Dr. Brett E. Gilbert
Case 2 by Dr. Brett E. Gilbert

Case Report 3

An 80-year-old female presented with a chronic apical abscess. Tracing of the sinus tract revealed tooth #30 as the responsible tooth (Fig. 3A). However, both adjacent teeth, #29 and #31, were also necrotic with asymptomatic apical periodontitis. Unfortunately, tooth #31 was not salvageable due to heavy destruction of the crown, and it was referred for extraction.

After administering local anesthesia and isolating with a dental dam, access cavities were prepared for both teeth #29 and #30 at the same time (in this case report, we are only focusing on tooth #29). Throughout the root canal instrumentation, the irrigant of choice was 5% NaOCl. A crown-down approach was performed with T-pro rotary files (Shenzhen Perfect Medical Instruments Co. Ltd., Guangdong, China). The final preparation size of the root canal for tooth #29 was 40/.04. NaOCl was activated with UltraX for a few minutes before obturation. Due to the proximity of the apex of tooth #29 to the mental foramen, the master GP cone was placed 1mm short of the working length, along with the least amount of AH Plus sealer. A warm vertical obturation technique was carried out. Post-obturation radiograph revealed a small amount of sealer extrusion from a lateral canal toward the lateral lesion. The tooth was temporized and referred for permanent restoration. A follow-up of 3 months shows favourable healing of the peri-radicular lesion and complete resolution of the sinus tract.

Fig. 3A

Case 3 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)
Case 3 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)

Fig. 3B

Case 3 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)
Case 3 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)

Fig. 3C

Case 3 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)
Case 3 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)

Fig. 3D

Case 3 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)
Case 3 by Dr. Mahmood Reza Kalantar Motamedi. (Restoration by Dr. Pardis Doosti)

Case Report 4

A 72-year-old female patient presented with pain in the upper right quadrant for one week, which was exacerbated by biting pressure. The diagnosis was tooth #3 pulp necrosis with symptomatic apical periodontitis. An enlarged apical lesion was noted on the palatal root extending coronally within the apical third of the palatal root on the distal (Fig 3A & 3B). RCT was completed using rotary instruments to a final canal preparation size of 18/.04 in the mesiobuccal and distobuccal canals (no 2nd mesiobuccal canal was present) and to a size 30/.04 in the palatal canal with ExactTaperHDC. Copious irrigation with Triton and activation with a laser-assisted endodontic irrigation protocol using the EdgePro laser. Obturation with GP and BC Hi Flow sealer using a single cone hydraulic condensation technique. A permanent access filling was placed. This case was completed in a single visit. The primary portal of exit on the palatal canal was directed toward the distal, and a lateral portal of exit on the distal aspect of the palatal root in the apical third was noted in the final image (Fig 4C). The visual confirmation of the lateral canal tells the story of the reality of the pulp system anatomy and etiology, providing context and confirmation that this is a lesion of endodontic origin and its position on the distal aspect of the palatal root was directed by the location of the lateral portal of exit of the necrotic canal.

Fig. 4A

Case 4 by Dr. Brett E. Gilbert
Case 4 by Dr. Brett E. Gilbert

Fig. 4B

Case 4 by Dr. Brett E. Gilbert
Case 4 by Dr. Brett E. Gilbert

Fig. 4C

Case 4 by Dr. Brett E. Gilbert
Case 4 by Dr. Brett E. Gilbert

Discussion

Lateral canals are typically not visible in preoperative radiographs, except in cases where there is a localized thickening of the PDL on the root’s lateral surface or the presence of a lateral periodontal lesion.4 The use of cone beam computed tomography can help to identify these structures in some cases. Lateral canal anatomy can be visualized on radiographs after root canal obturation when root filling material is forced into the ramifications, a phenomenon that we consider a “storyteller,” highlighting pulpal system anatomy and verification of the etiology of lateral peri-radicular lesions.

The complete cleaning of these ramifications, without leaving any tissue residue or infected debris, is a challenge. Complete cleaning of accessory or lateral canals is not likely feasible.7 However, in endodontic practice, the goal is to minimize the intracanal bacterial load as much as possible. Visual evidence of lateral sealer puffs helps confirm this has occurred during treatment.

If the pulpal tissue in these accessory innervations is necrotic and infected, leading to apical and lateral periodontitis, it becomes crucial to thoroughly clean and disinfect these lateral canals rather than simply filling them with an inert material. The shaping phase alone cannot reach these spaces, highlighting the importance of irrigation in three-dimensional cleaning. After shaping, the use of irrigants such as sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA), along with various activation techniques like subsonic activation, sonic activation, ultrasonic activation, laser-assisted and ultrasonic activation, can aid in the removal of pulp tissue remnants and hard tissue debris. The ultrasonic activation technique is a highly effective technique that does not require expensive devices for the activation of irrigation.8

Once the main root canal is adequately cleaned, it is ready for obturation. Some studies have shown that warm obturation techniques can effectively fill the previously cleaned lateral canals.9,10 Moreover, high-flow sealers can be helpful in filling lateral canals. In the cases presented in this study, BC sealers with a single-cone hydraulic condensation technique and AH-plus sealers with a warm vertical condensation technique were utilized for obturation.

Summary

Based on the literature, it appears that cleaning the lateral canals is more important than filling them. However, in clinical practice, when we observe the final image and see the sealer protruding into the lateral lesion, it indicates and confirms that the lesion originated from an extrusion of necrotic debris from the lateral canal. This also suggests that the lateral canal has been cleaned significantly enough for the sealer to pass through. Sealer travels more likely through a lateral canal that has been cleaned rather than a non-cleaned one. This tells the clinician a story confirming the presence of lateral anatomy and the likelihood that in necrotic cases, a peri-radicular lesion laterally adjacent to the root is of endodontic origin. 

Reprinted with permission from Endodontic Practice US (endopracticeus.com)

Disclosure: Dr. Motamedi and Dr. Gilbert have not received financial compensation for writing this article.

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Mahmood Reza Kalantar Motamedi received his dental degree from the Isfahan University of Medical Sciences in Isfahan, Iran in 2014. He completed his postgraduate program in endodontics at Azad University in Isfahan, Iran in 2020. He operates a private endodontics practice in Isfahan, Iran. 

Brett E. Gilbert graduated from the University of Maryland Dental School (DDS 2001, Endo, 2003). He is a professor at the University of Illinois at Chicago. He is a Diplomate of the American Board of Endodontics and founder of Access Endo and host of On The Cusp podcast. He has a private practice, King Endodontics PLLC, in Niles, Illinois.

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