Lauren Kuhn Nuth, DMD, MSD
A 63-year-old female patient presented with localized swelling and pain buccal to tooth #30 (FDI Tooth #46). The patient was seen earlier that day by her general dentist, who referred her for emergency endodontic treatment.
The patient presented with pulp necrosis and acute apical abscess. External cervical resorption was visible on the pre-operative PA radiograph and CBCT. Root canal treatment was performed in two appointments and was obturated with gutta-percha and BioRoot® Flow. At the second appointment, the external cervical resorption was accessed via the root canal system (internal, non-surgical approach), and the resorptive tissue was removed to the PDL level. The resorption was then repaired with Biodentine® and the access was sealed with composite. The patient presented for a 14.5-month follow-up and the apical bone was fully healed and the external cervical resorption remained well-repaired and had not recurred; all periodontal findings were also normal.
External cervical resorption—also called external invasive resorption—presents challenges for dentists and endodontists. The goals of treatment include halting resorption progression, maintaining as much natural tooth structure as possible, and repairing the resorption with a biocompatible material that supports both the periodontal health and the stability of the remaining tooth structure. Biodentine serves as a dentin substitute and helps clinicians predictably repair damaged and missing tooth structure. In addition, BioRoot Flow sealer builds on the legacy of Biodentine and serves as a bioactive root canal sealer which leads to excellent healing of the apical tissues.
BioRoot Flow and Biodentine are bioactive materials that can help save natural teeth.
A 63-year-old female patient presented with localized swelling and pain buccal to tooth #30 (FDI Tooth #46). The patient was seen earlier that day by her general dentist, who referred her for emergency endodontic treatment.
Figure 1a – Pre-op PA Radiograph Provided by Patient’s Dentist.
The patient awoke with critical pain and swelling of the alveolus buccal to tooth #30 (FDI #46). A lithium disilicate crown had been placed in 2017 due to a crack that crossed both the mesial and distal marginal ridges. The patient denied any pain until January 2022, when the tooth started feeling “different”. The patient’s general dentist exposed a periapical (PA) radiograph (Figure 1a). The dentist informed the patient of a “large infection” and possible “resorption”. The patient was then referred for an emergency endodontic appointment. The patient was prescribed Amoxicillin (500mg, 3x daily) by the dentist.
Diagnosis – Clinically, there was intra-oral fluctuant swelling and erythema confined to the alveolus, buccal to #30 (8 x 10mm). #30 was restored with a non-metallic crown, no caries were detected, and the crown had intact margins. The oral cancer screening was non-remarkable. With the consent of the patient, a limited field of view CBCT was exposed to the mandibular right posterior (see Figures 1b and 1c).
Pre-treatment Diagnosis: Pulpal necrosis with acute apical abscess.
Procedure and treatment – Emergency Treatment: Incision and drainage (I&D); Pulpal Debridement and Intracanal Medicament
Definitive Treatment: Root canal treatment and repair of external cervical resorption
Alternative Treatment Offered: Extraction
Therapy: The patient requested to move forward with endodontic treatment, and declined the alternative option of extraction.
Local anesthetic was placed, followed by an incision and drainage with a sterile size 15 blade. Tissue was dissected with a spoon excavator, and irrigated with 6mL sterile saline, followed by pressure to decompress the swelling. Hemostasis was observed. A dental dam with an 8a clamp was placed on the second molar, to improve access and visualization. Using a dental operating microscope (Zeiss Pico), the pulp chamber was accessed with a diamond bur, and all canal orifices were identified. Working length measurements were obtained for the four (4) canals: MB, ML, DB, and DL.
Patency was obtained on all canals, up to a size 15 k-file. The canals and chamber were irrigated with 10 mL of 6% NaOCI (30-gauge, side-vented needle). Cleaning and shaping were performed up to size 25/.06. The canals were irrigated with 6% NaOCl between all files. EndoActivator was used for 20 seconds in each canal. This process was completed twice. The canals were dried with negative pressure (microcapillary tip and surgical suction) and paper points. Calcium hydroxide was placed to the apex of each canal. A sterile cotton pellet was placed on the pulpal floor. Finally, 4+ mm of Cavit temporary restoration was placed in access and the occlusal surface was cleaned. The dental dam was removed, and a PA radiograph was exposed to document calcium hydroxide placement (Figure 2).
Figure 2 — Calcium Hydroxide radiograph at end of 1st appointment.
Post-operative instructions were reviewed. Pain management instructions were: 600 mg ibuprofen and 500 mg acetaminophen (paracetamol) should be taken in combination, every 6 hours.
The patient returned and stated, “Everything feels normal!” Clinically, there were no signs of lymphadenopathy, swelling, erythema, or sinus tract(s).
The incision was well-healed. The crown and temporary restoration were intact and sealed. Reviewed plan for an appointment, including the need to re-anesthetize, remove temporary restoration, re-clean the canals, obturate, and repair the external cervical resorption. The plan included sealing the access with composite, as long as the crown remained intact and well-sealed.
Local anesthetic was placed, followed by rubber dam isolation. Using a dental operating microscope, accessed through temporary restoration, and removed cotton. Removed calcium hydroxide from canals and chamber using NaOCl irrigation and sonic activation. Irrigated with 6% NaOCl. Repeated rotary instrumentation to working length to size 25/.06 (MB and ML), 35/.06 (DB and DL), and finished with the XP-3D shaper (all canals). Re-irrigated with 6% NaOCl between files.
Master cone radiograph was exposed, and adjustments were made to the gutta-percha, as needed. Performed final irrigation with 6% NaOCl and 17% EDTA and sonic activation. Injected BioRoot Flow sealer to mid-root of canals using the provided tip. Coated the master gutta-percha cones in the sealer and seated to working length. PA radiograph was exposed to verify that gutta-percha and sealer were in an optimal position (Figure 3).
Figure 3 – BioRoot Flow sealer and gutta-percha.
A heated plugger was used to sear gutta percha at the orifice level of all canals. Gutta-percha was compacted with Buchanan pluggers. A size 2 round discovery bur was used to remove gutta percha in the distal canals to the level of the external cervical resorption. A PA radiograph was exposed, and it was determined that some gutta percha remained near the resorptive defect and should be removed, in order to fully access the area (Figure 4).
Figure 4 – Check radiograph demonstrates that some gutta-percha remains near the resorptive defect and should be removed.
Used the dental operating microscope and a size 1 round discovery bur, the resorptive defect was cleaned to remove all gutta-percha. The bur was then used to remove dentin and resorptive tissue to the level of the periodontal ligament (PDL). A bleeding site was visible with the dental operating microscope, confirming the entry point for resorptive cells. The coronal portion of the distal canals was then cleaned with 6% NaOCl, sterile saline, and paper points.
Biodentine was placed incrementally in the distal root and over the pulp chamber floor (to serve as dentin replacement). A PA radiograph was exposed to confirm the location and density of the Biodentine placement (Figure 5).
Figure 5- Check radiograph to confirm location and density of Biodentine.
Biodentine was placed in bulk to serve as a dentin substitute, and the access was restored with composite. The rubber dam was removed, occlusion was adjusted, and post-operative PA radiographs were exposed (Figures 6a and 6b).
Figure 6a (left) and 6b (right). Immediate postoperative PA radiographs showing obturation of the canals with gutta-percha and BioRoot Flow sealer, resorption repair with Biodentine, and occlusal composite restoration.
The patient returned for a follow-up 14.5 months after completion of treatment. A PA radiograph and a limited field-of-view CBCT scan were exposed (see Figures 7a-c). The patient was asymptomatic, and all clinical findings were normal, including normal periodontal probings, normal mobility, lack of percussion, and biting sensitivity. Radiographically, the apical radiolucencies had healed and the external cervical resorption remained well-sealed and had not recurred.
External cervical resorption—also called external invasive resorption—occurs when osteoclastic/odontoclastic cells degrade dentin. This usually occurs when precementum–which protects the tooth structure from external cervical resorption—is missing. Precementum is non-mineralized, causing osteoclasts to be unable to bind to the root surface. However, in cases where there is a missing or damaged precementum, osteoclastic cells may mistake tooth structure for bone. Therefore, degradation of cervical dentin can occur. The clastic cells enter the tooth apical to the cemento-enamel junction and then spread through the dentin, as the dentin is degraded. The resultant resorption grows with time and has a vascular supply from the periodontium. However, if the entry point (apical to the CEJ) for osteoclasts or blood/vascularity is blocked, the resorption will stop.
Treatment of external cervical resorption presents challenges for dentists and endodontists. Since the entry point for osteoclasts is on the external tooth surface, many treatments are surgical in nature. Surgical treatments allow the provider to directly visualize the location where osteoclasts have entered the tooth; this entry point is then repaired/sealed by the clinician, to halt the resorption process. However, some locations may be difficult or impossible to treat in a conservative or predictable manner. Locations, where external cervical resorption is challenging to treat, include interproximal surfaces and the distal surface of second molars. In addition, surgical treatments may require crown lengthening—the removal of healthy and/or supportive bone—in order to facilitate visualization and repair of the resorption. While surgical repairs certainly have their place and are a critical skill set, there are cases where a non-surgical repair for external cervical resorption may provide a predictable outcome, without the need for incisions, crown lengthening, or other surgical steps.
A non-surgical repair of external cervical resorption requires an accurate diagnosis, a clear understanding of where the resorption began (entry point for osteoclasts), high magnification, and provider skills of patience and dexterity. If the provider does not use a small instrument—such as an ultrasonic or small round bur—to remove resorption and reach the level of the PDL space, then he/she cannot adequately seal and block the location where osteoclasts are entering the tooth.
In this case, a surgical operating microscope (Zeiss Pico) was utilized, and the clinical findings were matched against the CBCT images. The goals of treatment, in this case, were two-fold: 1) Perform a high-quality root canal treatment that would allow healing of the apical periodontium and acute apical abscess; this was accomplished through root canal treatment and obturation with gutta-percha and BioRoot Flow sealer. 2) Repair and stop external cervical resorption progression, while maintaining as much natural tooth structure as possible. A slow-speed, round discovery bur was used to clean and access the resorption all the way to its entry point at the PDL. The resorption was then cleansed with sodium hypochlorite (NaOCl), dried, and repaired with Biodentine.
Using high-quality materials and having a thorough plan for treatment success can provide patients with long-term results. In this case, both BioRoot Flow and Biodentine were well-tolerated by the patient and the periodontal and periapical tissues. The 14.5-month follow-up shows the results of treatment: healing of the periapical radiolucencies and acute apical abscess, as well as repair of external cervical resorption, without recurrence.
BioRoot Flow and Biodentine are bioactive materials that can help save natural teeth, even in cases with large apical radiolucencies, infection, and external cervical resorption.
Dr. Lauren Kuhn Nuth is a graduate of the Harvard School of Dental Medicine (DMD) and the Medical University of South Carolina (MSD in Endodontics). She is a board-certified endodontist (Diplomate of the American Board of Endodontics) and is active in hosting webinars and in-person educational events for dentists. She has been an Adjunct Assistant Professor at the University of Minnesota School of Dentistry since January 2020. She has published case-based research in the Southeast Case Research Journal and co-authored publications in Dental Materials, The Journal of Advanced Prosthodontics, and Decisions in Dentistry. In 2019, Dr. Kuhn traveled to Jamaica with the Christian Dental Society, where she performed endodontic treatment for patients in need.
Address for correspondence – laurenkuhn1@gmail.com
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