Treatment of a first molar with external root resorption in the middle third using endodontic microsurgery and vital pulp therapy: a case report

Abstract

Background

External root resorption is a pathologic process starting from the root surface of the tooth. At present, there are few reports about the treatment of vital pulp preservation in the tooth with external root resorption.

Case presentation

A 14-year-old Asian female visited the hospital of the present authors, complaining of the dentition was irregular. The results of CBCT revealed extensive ERR in the middle third of the root of tooth #16 and tooth #15 was impacted. After treatment, tooth #15 was removed, and the vital pulp of tooth #16 was preserved. The patient had no discomfort and was ready for future orthodontic treatment.

Conclusion

This paper reports the cases of extracorporeal resorption of tooth #16 caused by impacted tooth #15 combined with EMS and VTP during impacted tooth extraction. This report aimed to describe the causes of ERR and provide a viable potion to treat ERR in selected cases. Nevertheless, further clinical trials are needed for its long-term result.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-025-06514-0.

Background

The American Association of Endodontics (AAE) defines “resorption” as a physiological or pathological process that results in the loss of dentin, cementum, or bone tissue [1]. The inducing factors of external root resorption (ERR) are complex and varied. The common factors of ERR are mechanical injury or inflammation [2]. It is often seen that impacted tooth embedded in bone lead to root resorption of adjacent tooth [3–6]. The incidence of impacted premolars is approximately 0.5%. In the early stage of the process of ERR caused by impacted tooth, the characteristic clinical manifestations are often lacking, and are often detected after the pulpitis or mobility of the adjacent tooth. If the resorptive process persists, there will be an additional loss of dental hard tissue. Should ERR not be managed effectively, it may render the tooth irreparable and perforation of the root canal, ultimately necessitating extraction. Therefore, the factors leading to ERR should be removed as early as possible such as removal of an impacted tooth [7]. For the middle third of the root with inflammation, because root canal therapy is not possible, endodontic microsurgery (EMS) can be used to expose the resorption area, so as to control the infection and promote the healing of periapical bone [8].

However, treatment for non-inflammatory resorption in the root third of the tooth is less common. Herein, we report an unusual case of vital pulp with severe root resorption of the tooth #16. a new vital pulp therapy approach using the iRoot BP Plus through the EMS was designed in this case report as an effective method for the treatment of ERR with vital pulp, in which the details of the surgery process and considerations about the technique were discussed.

Case report

A 14-year-old Asian female visited the hospital of the present authors, complaining of the dentition was irregular. The patient was found to have the impacted tooth #15 during the preoperative examination of treatment in the Department of Orthodontics (Fig. 1). The Orthodontist was recommended to consider orthodontic treatment after removing the tooth #15. Then, the patient was transferred to Department of Oral and Maxillofacial Surgery, where a cone beam computed tomography (CBCT) was performed. The results of CBCT revealed extensive ERR in the middle third of the root of tooth #16 (Fig. 2), Since there is currently no gold standard for ERR, physician recommend that patients consider surgical extract tooth of #16 and surgical exposure of the impacted tooth #15 with orthodontic alignment (New Tom VGi, Italy, voxel size 0.15 mm). The other option was extracting tooth #16 and tooth #15 at the same time, and wait until the patient is an adult to undergo dental implant treatment. The option of removing the tooth #16 was discussed with the patient. She preferred to retain the tooth #16, then she was referred to the Department of Cariology and Endodontics for evaluation of the preservation value of the tooth #16. The patient had a Class I occlusion, and the tooth #16 was stable. The results of pulp vitality tests and pulp sensibility tests showed that the pulp was vital. If only the affected tooth #15 is extracted without addressing the ERR portion of tooth #16, there is a possibility that tooth #16 may develop pulpitis in the future due to decay or other contributing factors. ERR can make root canal treatment more difficult, and patients need to pay a lot of time and money. Therefore, it is a challenge to achieve the treatment of the tooth #16 with ERR while preserving its vital pulp.

Fig. 1.

(A) Buccal photo of the right maxillary teeth, tooth #15 is completely impacted. (B) The tooth #16 Superficial caries in the dental crown. (C) Palatal photographs showed good periodontal condition of the right maxillary teeth

Fig. 2.

(A-B) CBCT showing an impacted tooth #15 between the tooth #16 and tooth #14. (C-D) Three-dimensional reconstructions from different angles show the position of impacted tooth #15. (E-F) The tooth #15 was obstructed on the palatine side of tooth#16, and the crown of tooth #15 was located inside the root canal of the palatine root of tooth #16. (Red arrow shows impacted tooth #15)

Based on a thorough analysis of the patient’s complain, clinical manifestations, imaging findings and routine blood tests, we choose a conservative treatment approach. A multidisciplinary team involving experts from endodontics, oral surgery and orthodontics recommended extracting tooth #15, then tooth #16 direct pulp capping treatment was performed. A written informed consent for tooth #15 and tooth #16 was obtained from the patient’s guardian after explaining the treatment procedure, benefits, and risks.

The anaesthesia was secured through local infiltration with the 3.4 ml 4% articaine hydrochloride with 1:100,000 epinephrine (Produits Dentaires Pierre Rolland, France) was administered. A vertical incision was made at the mesial of the tooth 14#, and a horizontal incision was made at the palatal gingival margin from the tooth #14 to the tooth #17 (Fig. 3A). Preparation of full thickness mucoperiosteal flap was reflected to expose the site of the impacted tooth #15, then removed using odontomy and delivered from the socket (Fig. 3B).

Fig. 3.

(A) Flap surgery revealed tooth #15 crown. (B) Removal of the tooth #15. (C) Pulp tissue in the palatal root canal of tooth #16. (White arrow shows vital pulp) (D-E) Part of the pulp tissue of tooth #16 was removed and retention cavity was prepared. (F) The iRoot BP Plus was used to seal the area of ERR. (G) iRoot BP Plus fitted with palatal root surface. (H) CGF overlayed on iRoot BP Plus surface. (I) Sutures were placed

After removal of tooth #15, it can be observed that the external root resorption site of 16 is inclined (Fig. 3C). The middle root canal and pulp tissue of tooth #16 were exposed in the extraction pit, and the pulp tissue was slightly bleeding. After rinsing with saline, applied mild pressure with a sterile cotton pellet to stop bleeding. The exposed pulp tissue was removed with an ultrasonic tip and the retention form was prepared (Fig. 3D-E). The prepared root canal cavity was gently air-dried and filled with Bioceramic iRoot BP Plus (Innovative BioCeramix, Canada) (Fig. 3F-G).

To prepare concentrated growth factors (CGF), the venous blood was collected from the patient using sterile vacuum tubes. First, a venous blood sample of approximately 10 mL was collected from the patient and injected into a sterile centrifuge tube. The centrifuge tubes were then immediately placed into the CGF Medifuge centrifuge device (Silfradent Srl, Sofia, Italy) and subjected to centrifugation following a specific protocol: 30 s of acceleration, 2 min at 2700 rpm (600 g), 4 min at 2400 rpm (400 g), another 4 min at 2700 rpm (600 g), followed by 3 min at 3000 rpm, and finally, a deceleration period of 36 s. This process resulted in the separation of the blood into three distinct layers from top to bottom, with the middle layer representing the CGF layer.

After centrifugation, CGF gel in the middle layer and was carefully isolated from the red blood cell clots. Following the capping of the root canal and the residual pulp tissue, the wound was thoroughly covered with CGF gel (Fig. 3H). Subsequently, the flap was repositioned coronally and securely sutured using non-resorbable sutures (Fig. 3I).

The sutures in the surgical area were removed 7 days after the procedure (Fig. 4A-C). Because the patient was worried about the wound pain caused by brushing, the oral hygiene of the operative area was slightly poor, and there was no obvious discomfort in addition.

Fig. 4.

(A) Buccal photos showed some soft scale attached to the crown surface. (B) The photo of the occlusal surface showed that the position of tooth #16 had no change compared with that before operation. (C) Palatal photographs show no periodontal tissue swelling in the operative area

The panoramic film was performed after the operation (Fig. 5A). One month after surgery, the periapical X-ray showed an increase in bone density at tooth #15 extraction pits (Fig. 5B). The patient was followed-up for 6 months with radiographic signs of continuous dense periodontal membrane images of the tooth #16 palatal root (Fig. 5C), and the tooth#16 was no pain to palpation and percussion at the time of clinic assessment. CBCT scans at the 12-month follow up revealed a continuous and dense palatine bone plate of tooth #16. The palatine root canal of tooth #16 showed high density iRoot BP Plus image, and iRoot BP Plus was closely fitted to the root canal, without dislocation and other problems (Fig. 5D-F). Clinical evaluations revealed normal responses to percussion and palpation tests, have a periodontal probe ≤ 3, and the tooth was responsive to the electric pulp test. An occlusion with a Class I molar relationship (Fig. 5G-I), The patient was very satisfied with the treatment results and chose to complete the orthodontic treatment plan. Further follow-up examinations were planned. The patient was very satisfied with the treatment results and chose to complete the orthodontic treatment plan. Further follow-up examinations were planned.

Fig. 5.

(A) High density image of the palatal root of tooth #16 sealed with iRoot BP Plus. (B) The image of bone healing at the tooth #15 extraction pit. (C) The periodontal membrane at the tooth #16 palatal root is dense and continuous. (D) CBCT, coronal view showing iRoot BP Plus is located in the middle root canal of the tooth #16 palatal roots and palatine alveolar bone height is normal. (E) Axial and sagittal. (F) tomography images showing iRoot BP Plus closely adhered to the tooth #16 palatal root, and the bone density around the palatal root increased. (G) No obvious abnormality was found in the palatal gingiva of tooth #16. (H) The patient’s occlusal photo showed that the midline of the upper and lower dentition was not aligned. (I) Class I occlusal relationship. (White arrows showing the iRoot BP Plus)

Discussion

Using CBCT for the initial evaluation and diagnosis of resorption, in addition to two-dimensional radiography, is essential. Previous studies on ERR have relied on root canal sections and panoramic radiographs to make judgments, with the detection rate of ERR ranging from 0.3–7.0% [9–11].Some scholars have found that CBCT has a higher detection rate for ERR and a higher accuracy in diagnosing ERR [12]. In the current case, given the extent of the root resorption given the extent of the root resorption reached the pulp, the final diagnosis was established as severe resorption [13].There are many mechanical or chemical stimuli that can lead to the pathological process of ERR, such as infection, pressure from impacted teeth or tumors, trauma, and orthodontic movement. Different causes of ERR require different treatment plans. The main reason for the neighboring teeth ERR caused by impacted teeth is the pressure exerted on the neighboring root by the impacted teeth, and the progress of neighboring teeth ERR can be interrupted by removing the impacted teeth adjacent to it [2].

While the removal of tooth #15 without addressing tooth #16 presents an alternative approach for managing external resorption, it is important to note that tooth #16 may not exhibit any pulp tissue inflammation post-surgery. However, considering the patient’s young age, there exists a possibility that tooth #16 could develop caries or even pulpitis as she continues to grow [14]. Consequently, root canal therapy for tooth #16 may become unfeasible due to the healing process of the palatine bone.

In cases of surgical intervention to treat progressive external root resorption, treatment is required to prevent tooth loss or even broken roots. We did not choose to truncate the apical segment of the palatal root directly because the disproportion of the crown and root may lead to loosening of the teeth in the long term. Therefore, it was decided only to remove the pulp of resorptive area and rebuild that part of the root with iRoot BP Plus. In the previously reported cases of external resorption, the different materials have been used to restore ERR cavities. These include amalgam [15], composite resin [16], mineral trioxide aggregate (MTA) [17], and glass ionomer [1]. The iRoot-BP Plus exhibited good biocompatibility, sealing ability and antibacterial activity. It has also been reported to be successfully used for procedures such as pulpotomy, pulp floor perforation repair and used as a pulp capping material for vital pulp therapy [18, 19]. Therefore, we chose to utilize iRoot-BP Plus to perform EMS in this case. Recent reports indicate that the combination of CGF and iRoot-BP Plus exhibits a synergistic effect on anti-inflammatory properties, resulting in enhanced pulp healing compared to either CGF or iRoot-BP Plus used independently [20]. Therefore, we also covered the iRoot-BP Plus with CGF, and at the same time, it could prevent the iRoot-BP Plus from falling off from the root canal. Further follow-up studies will indicate if the use of CGF and iRoot-BP Plus were advantageous in the long term.

At the 12-month follow-up examination, the patient remains asymptomatic, the tooth #16 maintained good pulp vitality (Clinical evaluations revealed normal responses to percussion and palpation tests, and the tooth was responsive to the electric pulp test), which may be because the process of ERR begins in the periodontal ligament and is unrelated to the pulp, and during the ERR process, the pulp is not infected by bacteria [21, 22]. Moreover, only the interruption of the blood supply leads to the necrosis of the pulp, as long as there is blood supply, the pulp can maintain vitality [23]. The blood supply of the pulp comes from small arteries that pass through the apical foramen and lateral root branches and form a capillary network in the pulp chamber, through accompanying veins that drain back, the capillary network is located below the layer of odontoblastic cells and does not enter the dentin. Theoretically, multiple roots can compensate for the blood supply of the damaged root and ensure the survival of the pulp, the blood supply to the upper part of the palatine root may come from capillary network, while the blood supply to the apical part may come from the arteriole through the apical foramen. Therefore, the age of the patient is one of the important factors in the success of this case [24–26]. Additionally, during the extraction of impacted teeth, it should be minimally invasive by dividing the teeth to reduce resistance, so as to minimize the mechanical force on the neighboring tooth root during the operation. By minimizing the amount of bone removed, the impact on the bone microenvironment of the root area of the neighboring tooth is minimized in order to minimize the inflammation of the root apex and periodontal tissue of the neighboring tooth caused by the surgical trauma. The limitation of this case is that the current follow-up time is short, and it is not possible to determine the long-term past effect of treatment. At present, the patient has not started orthodontic treatment.

Conclusion

This case represents the first instance demonstrating that the use of EMS in conjunction with vital pulp therapy may provide a significant opportunity for severely affected teeth with an uncertain prognosis to remain functional and free from signs and symptoms. This finding confirms the efficacy of this procedure as a viable treatment option in selected cases. However, it is important to note that the prognosis associated with this method may be influenced by factors such as the patient’s age and tooth development status. Further clinical trials are warranted to assess its long-term outcomes.

Electronic supplementary material

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Author contributions

Leiying Miao and Sufeng Zhao performed the clinical diagnosis and treatment. Yue Zhao and Shuangshuang Ren drafted the manuscript. Mingyue Cheng and Chao Liu collected clinical data and was involved in writing the manuscript. All authors read and approved the final manuscript prior to submission.

Funding

This study was supported by “2015” Cultivation Program for Reserve Talents for Academic Leaders of Nanjing Stomatological School, Medical School of Nanjing University (number 0223A203), Nanjing Clinical Research Center for Oral Diseases (number 2019060009); and the Natural Science Foundation of Jiangsu under Grant (number BK20221177).

Data availability

All data analyzed during this study are included in this published article.

Declarations

Ethics approval and consent to participate

Surgery procedures were approved by the Ethics Committee of Nanjing Stomatological Hospital (contract awarded to NJSH-2024NL-031, Nanjing, China); Consent to participate was obtained from the patient.

Consent for publication

Written informed consent for publication was obtained from the patient and her parents for the publication of this case report.

Competing interests

The authors declare no competing interests.

Conflict of interest

The authors declare no conflict of interest.