Internal and external inflammatory root resorption: Report of two cases and their endodontic management

Case 1

Inflammatory non-perforating internal root resorption

A 25-year-old female presented with dull pain in the left maxillary anterior region for one week. The patient reported a history of dental trauma 10 years earlier and previous dental treatment in the same region. Her medical history was non-contributory.

Intraoral examination revealed a fixed prosthesis extending from teeth #11 to #22, which was removed for further evaluation [Figure 1a]. Teeth #11, #12, #21, and #22 had previously undergone root canal treatment. Tooth #22 exhibited mild tenderness to percussion, while no swelling, sinus tract, periodontal pocketing, or abnormal mobility was observed. As tooth #22 had been previously endodontically treated, pulp sensibility testing was not indicated.

Close

Figure 1 Case 1: Internal inflammatory resorption (a) Preoperative photograph. (b) Preoperative IOPAR (c) Preoperative panoramic radiograph. (d) Preoperative CBCT image showing a sagittal view of tooth 22 with an internal resorptive defect. CBCT: Cone-beam computed tomography, IOPAR: Intra-oral periapical radiograph

Export to PPT

Preoperative intraoral periapical radiography revealed an irregular radiolucent enlargement involving the middle and apical thirds of the root canal space of tooth #22, suggestive of an internal resorptive defect. A periapical radiolucency was also evident, indicating persistent apical pathology [Figure 1b]. Teeth #11, #12, and #21 demonstrated inadequate obturation with associated periapical radiolucencies [Figure 1c]. Although these teeth were asymptomatic and were not considered the primary source of the patient’s chief complaint, the radiographic findings suggested persistent apical disease requiring nonsurgical retreatment.

Cone-beam computed tomography (CBCT) using a 5 × 5 cm field of view confirmed the presence of a non-perforating internal resorptive defect involving the middle and apical thirds of tooth #22, along with an associated periapical radiolucency [Figure 1d]. The three-dimensional assessment provided by CBCT enabled accurate characterization of the lesion and exclusion of external root resorption or root perforation.

Based on the clinical findings, radiographic examination, and CBCT evaluation, tooth #22 was diagnosed as a previously treated tooth with a non-perforating internal root resorption defect associated with symptomatic apical periodontitis. Teeth #11, #12, and #21 were diagnosed as previously treated teeth with persistent apical periodontitis secondary to inadequate obturation. Considering the strategic importance of the anterior region and the presence of adequate remaining tooth structure, a conservative nonsurgical treatment approach was planned, including retreatment of all affected teeth.

Treatment procedure

First visit

After obtaining informed consent, local anesthesia was administered using 2% lignocaine with 1:80,000 adrenaline (Lignox 2% A, Warren Indoco Remedies Ltd., Mumbai, India), and rubber dam isolation was achieved. Following access cavity preparation using an Endo-Access bur (Dentsply Maillefer, Ballaigues, Switzerland), the working length was determined using an electronic apex locator (Root ZX Mini, Model RCM-7; J. Morita Mfg. Corp., Kyoto, Japan) and confirmed radiographically [Figure 2a].

Close

Figure 2 Case 1: Internal inflammatory resorption (a) Working length established. (b) Sectional obturation was done in the apical 1/3rd of the canal. (c) The remaining portion of the canal was filled with MTA, followed by a post-endodontic restoration (d) 12-month follow-up radiograph demonstrating reduction in periapical radiolucency and evidence of periapical healing. MTA: Mineral trioxide aggregate.

Export to PPT

Biomechanical preparation was carried out using a crown-down technique with rotary nickel–titanium instruments (ProTaper Gold; Dentsply Sirona, Ballaigues, Switzerland) up to size F3. Copious irrigation was performed using 2.5% sodium hypochlorite and normal saline. To enhance the debridement of the irregular resorptive defect, passive ultrasonic irrigation was performed using IrriSafe ultrasonic tips (Acteon Group, Mérignac, France). Calcium hydroxide paste (UltraCal XS; Ultradent Products Inc., South Jordan, UT, USA) was placed as an intracanal medicament to eliminate residual bacteria, dissolve necrotic tissue, and inhibit clastic activity. The access cavity was sealed with Cavit-G temporary restorative material (3M ESPE, Seefeld, Germany).

Second visit

At the two-week recall, the patient was asymptomatic with no tenderness to percussion. The intracanal medicament was removed using 10% citric acid solution (CitoCid; Ammdent, Mohali, Punjab, India) with passive ultrasonic irrigation activated using an Ultra X ultrasonic activator (Eighteeth/ Changzhou Sifary Medical Technology Co., Ltd., Changzhou, Jiangsu, China) for thorough debridement. Considering that the resorptive defect involved the middle third of the canal, a hybrid obturation strategy was employed. The apical one-third of the canal was obturated with gutta-percha cones (Dentsply Sirona, Ballaigues, Switzerland) using a sectional obturation technique to establish an apical seal [Figure 2b]. The remaining canal space, including the resorptive defect, was filled with mineral trioxide aggregate (ProRoot MTA; Dentsply Sirona, Tulsa, OK, USA) to achieve a three-dimensional seal and reinforce the weakened root structure [Figure 2c]. Teeth #11, #12, and #21 were retreated and obturated using lateral compaction with gutta-percha cones (Dentsply Sirona, Ballaigues, Switzerland) and a bioceramic sealer (Bio-C Sealer; Angelus, Londrina, Paraná, Brazil).

Follow-up

At the 12-month follow-up, the patient remained asymptomatic. Clinical examination revealed no tenderness to percussion or palpation. Radiographic evaluation demonstrated a reduction in periapical radiolucency, evidence of periapical healing, and arrest of the resorptive process, indicating a favorable treatment outcome [Figure 2d]. Continued long-term monitoring has been advised to assess the stability of healing and the long-term prognosis of the treated tooth.

Case 2

External inflammatory apical root resorption

A 24-year-old female presented with intermittent pain in the lower right posterior region involving tooth 46, aggravated on mastication. The tooth had undergone root canal treatment and full-coverage crown placement seven years earlier. Her medical history was non-contributory.

Intraoral examination showed a crown-restored mandibular right first molar (tooth 46) that was tender on vertical percussion, indicating symptomatic apical inflammation. No sinus tract, swelling, periodontal pocketing, or mobility was observed.

Preoperative orthopantomogram showed a previously treated tooth 46 with periapical radiolucency at both mesial and distal apices, along with root shortening, irregular external surfaces, loss of apical contour, and widened foramina— consistent with external inflammatory apical root resorption [Figure 3a]. Intraoral periapical radiograph confirmed these findings [Figure 3b].

Close

Figure 3: Case 2: External inflammatory apical root resorption. (a) Preoperative orthopantomography (OPG) of crown-restored tooth #46 showing periapical radiolucency at both root apices with apical shortening, irregular root surfaces, open foramina, and loss of apical contour, consistent with external inflammatory apical root resorption. (b) Intraoral periapical radiograph after removal of the crown and previous restorative/root filling material. (c) Clinical photograph after crown removal showing the underlying core structure and access cavity for retreatment. (d) Clinical photograph under rubber dam isolation showing access opening during retreatment after removal of previous obturation material, canal location, and initiation of biomechanical preparation.

Export to PPT

Based on clinical and radiographic findings, tooth 46 was diagnosed as a previously treated tooth with symptomatic apical periodontitis and external inflammatory apical root resorption secondary to persistent intracanal infection. Considering its strategic importance, adequate remaining structure, and the patient’s preference, nonsurgical endodontic retreatment was planned.

Treatment procedure

First visit

After informed consent, the crown was removed under local anesthesia (Lignox 2% A, Warren Indoco Remedies Ltd., Mumbai, India). Examination revealed the underlying core and access cavity [Figure 3c]. Previous restorative material was removed, access was refined, and canal orifices were located. The old root canal filling was retrieved under rubber dam isolation [Figure 3d]. Working length was established using an apex locator (Root ZX Mini, Model RCM-7; J. Morita Mfg. Corp., Kyoto, Japan) and confirmed radiographically, followed by biomechanical preparation with copious sodium hypochlorite and saline irrigation.

Due to active resorption and persistent periapical pathology, a freshly prepared antibiotic–corticosteroid intracanal medicament (prepared by crushing minocycline tablet(100 mg) as the antibiotic and triamcinolone tablet (4 mg) as the corticosteroid, mixed in a 1:1 ratio by weight with sterile saline as the vehicle to obtain a paste of suitable consistency) was placed and periodically replaced over three months to suppress inflammation, inhibit osteoclastic activity, and reduce residual microbial load.

Interappointment phase

After symptom resolution, the intracanal medicament was replaced with calcium hydroxide (UltraCal XS; Ultradent Products Inc., South Jordan, UT, USA) as a second-stage dressing to create an alkaline environment, inhibit osteoclastic activity, provide antibacterial action, and promote periapical healing.

Final obturation visit

At recall, the patient was asymptomatic with no percussion tenderness. Due to severely resorbed, open apices, conventional gutta-percha obturation was not feasible; hence, MTA (ProRoot MTA; Dentsply Sirona, Tulsa, OK, USA) obturation was performed under rubber dam isolation [Figure 4a].

Close

Figure 4: Case 2: Nonsurgical retreatment, restoration, and follow-up of tooth #46. (a) Obturation with mineral trioxide aggregate (MTA) under rubber dam isolation. (b) Placement of a glass ionomer cement layer over MTA to facilitate composite bonding. (c) Postoperative radiograph showing MTA obturation and completed composite restoration (d) Clinical photograph showing completed composite restoration. (e) Six-month follow-up radiograph of the crown-restored tooth showing reduction in periapical radiolucency and evidence of healing. (f) 12-month follow-up radiograph showing further reduction in periapical radiolucency and continued healing in relation to tooth #46; root canal treatment with definitive restoration was also completed in tooth 47.

Export to PPT

A glass ionomer cement layer (Ketac Molar Easymix; 3M ESPE, Seefeld, Germany) was placed over the MTA to aid composite bonding [Figure 4b], followed by composite restoration (Tetric N-Ceram; Ivoclar Vivadent AG, Schaan, Liechtenstein). Postoperative radiograph confirmed satisfactory obturation and restoration [Figure 4c], and clinical examination showed a completed restoration [Figure 4d]. The tooth was then prepared and restored with a full-coverage crown, achieving satisfactory form and occlusion.

Follow-up

At the six-month follow-up, the patient was asymptomatic with no tenderness to percussion or palpation. Radiographs of the crown-restored tooth showed reduced periapical radiolucency, re-established bone density, and arrest of resorption [Figure 4e].

At 12-month follow-up, further reduction in periapical radiolucency and continued healing were observed, indicating a favorable outcome [Figure 4f]. Root canal treatment with definitive restoration was also completed in tooth 47.

The overall clinical course, diagnostic process, therapeutic interventions, and follow-up outcomes of the present case series are summarized in a CARE guidelines–based flowchart [Figure 5].

Close

Figure 5: CARE guidelines–based clinical flowchart summarizing patient presentation, diagnostic workflow, treatment interventions, and follow-up outcomes of the two reported cases. RCT: Root canal treatment, CBCT: Cone-beam computed tomography, GP: Gutta percha, MTA: Mineral trioxide aggregate.

Export to PPT

Internal inflammatory root resorption

Internal inflammatory root resorption (IIRR) is an uncommon, progressive condition caused by damage to the odontoblastic layer and predentine, often due to trauma or chronic pulpal inflammation. Bacterial contamination with residual vital inflamed pulp sustains clastic activity, leading to intraradicular dentin loss. Radiographically, it appears as a symmetrical, round or oval “ballooning” of the root canal space.^[9]

In Case 1, a history of trauma and prior dental treatment— known risk factors—were present. The lesion was largely asymptomatic with mild percussion tenderness, consistent with reports that internal resorption often remains silent until secondary apical periodontitis develops. CBCT was valuable in confirming the non-perforating nature and extent of the lesion. It is recommended that conventional radiographs cannot clearly differentiate internal from external resorption or assess perforation.^[10]

Management of IIRR involves the removal of inflamed or necrotic pulp to arrest clastic activity. In this case, calcium hydroxide was used as an intracanal medicament for its antibacterial effect and alkaline pH, which inhibits resorptive cells. MTA obturation was used to fill the resorptive defect due to its superior sealing ability and suitability for irregular defects, preserving tooth structure while eliminating pathology.^[11]

External inflammatory apical root resorption

External inflammatory root resorption (EIRR) occurs when damage to the cementum or periodontal ligament combines with root canal infection. Bacterial by-products diffuse through dentinal pathways, triggering inflammation and activating clastic cells on the external root surface. This process commonly follows trauma such as luxation or avulsion injuries, but may also occur in teeth with longstanding pulpal necrosis and apical periodontitis.^[12]

Case 2 showed external inflammatory apical root resorption localized to the apex, consistent with reports that chronic pulpal infection more commonly causes apical rather than lateral resorption. Radiographically, these lesions show apical shortening, irregular root contours, ragged apices, and periapical radiolucency. As early stages are often asymptomatic, diagnosis mainly depends on radiographic examination.^[3]

The primary aim in EIRR is to eliminate intracanal infection and remove the inflammatory stimulus. Timely root canal treatment can arrest resorption and promote healing, whereas delayed intervention may lead to extensive structural loss, perforation, or extraction.^[5] Therefore, the successful management of Case 2 reinforces the importance of prompt diagnosis and immediate endodontic disinfection once EIRR is recognized.

Differentiating internal from external resorption on two-dimensional radiographs is challenging: internal lesions remain centered on the canal, while external lesions shift on angled views. Overlapping anatomy can obscure this distinction. CBCT provides a three-dimensional assessment of lesion location, extent, perforation, and remaining dentin, improving diagnosis and treatment planning; it was essential in Case 1 and useful for evaluating external defects.^[11] The principal differences between internal inflammatory root resorption and external inflammatory root resorption are summarized in Table 1.

These two cases emphasize that inflammatory resorption is not a single disease entity but a group of biologically distinct pathologies requiring individualized management. Internal resorption requires removal of the vital inflamed pulp tissue sustaining the lesion, whereas external inflammatory resorption requires elimination of infection diffusing through the canal system to the periodontal tissues. Despite different mechanisms, both lesions share a common principle: early endodontic intervention can preserve natural teeth that might otherwise be lost. Long-term follow-up is important in inflammatory root resorption to confirm arrest of resorptive activity and sustained periapical healing. Both cases showed favorable clinical and radiographic outcomes during follow-up, supporting the effectiveness of timely endodontic intervention. This report of two cases followed the CARE Guidelines, ensuring transparent, complete, and methodologically sound reporting, with clear documentation of history, diagnosis, treatment, outcomes, and follow-up.^[13]