Spontaneous remission of internal root resorption during orthodontic treatment: A clinical follow-up report

Internal root resorption (IRR) is a pathologic process that occurs because of external stimuli that affect the pulp and result in the loss of dentinal tissue. The occurrence of IRR is considered relatively rare, and the etiology is not fully understood, although trauma is believed to be the main etiologic agent. The current study presented a case report of spontaneous remission of an IRR lesion diagnosed during orthodontic treatment. The lesion was characterized by a circular and delimited radiolucent image, located in the apical third of the root canal of the maxillary right lateral incisor diagnosed during orthodontic treatment. After the diagnosis, clinical and radiographic follow-up was performed without any intervention. The follow-up radiographic images showed loss of contour definition and reduction in the size of the lesion. At the end of orthodontic treatment, 27 months after diagnosis, the space of the lesion had been filled by tissue with similar radiopacity to the adjacent dentin, and the tooth did not change its color and response to mechanical and thermal stimuli. Eight years after the end of the treatment, the maxillary right lateral incisor still presented normal responses to vitality tests and color stability; therefore, it was impossible to notice the root canal space. The reported patient presents a possible behavior of the IRR characterized by spontaneous remission of the lesion. However, nonendodontic treatment after diagnosis should not be the routine therapy adopted for IRR because of the potential risk to the tooth.


  • Internal root resorption lesions are generally asymptomatic.

  • They are often detected during routine radiological examinations.

  • Early diagnosis allowed observation and spontaneous regression of the resorption.

  • The space gradually filled with less organized tissue.

Internal root resorption (IRR)—also known as intracanal resorption, odontobastoma, and endodontic or internal granuloma—is a pathologic process that occurs inside the pulp cavity, toward the outer surface of the crown or root, in which the dentin and the odontoblast layer are removed by the action of multinuclear cells with odontoclastic action. , Such lesions are characterized by a symmetrical, ovoid or circular, and delimited radiolucent area which can be present in any region of the root canal system being histologically characterized by vascularized granulation tissue, infiltrated by lymphocytes, histiocytes, and leukocytes. ,

The etiology and pathogenesis of IRR have not yet been fully understood. It is believed that the etiologic factors might be trauma injuries, chronic inflammation of infectious origin in pulp or periodontal tissues, surgical procedures, excessive pressure on an impacted tooth, a chronic pulp tumor or inflammation, in addition to mechanical, chemical, or thermal injuries that have been suggested as causative agents of this condition. ,

IRR lesions are generally asymptomatic and detected during routine radiological examinations, requiring a careful differential diagnosis to proceed with the appropriate therapy. When symptomatic, they can present spontaneous, intense pain similar to pulpitis in the initial phase. In a later phase, the pulp can become necrotic, causing symptoms of periapical pathologies, with almost always pulsatile pain, dental mobility, and sensitivity to percussion.

The objective of this article is to describe a clinical patient, with an 8-year follow-up, of an IRR lesion on the maxillary right lateral incisor, which had been diagnosed and presented spontaneous regression later on during orthodontic treatment.

Case report

At the beginning of the treatment, the patient, a 22-year-old female dentist, was in good general health and presented complete permanent dentition, Class II dental and skeletal malocclusion, marked lack of space in the maxillary and mandibular dental arches, and the maxillary right lateral incisor in crossbite. To obtain enough space in the dental arches to correct malocclusion, the left first molars and the right first premolars were extracted in both arches. This patient’s orthodontic treatment was described previously, and full treatment records are available in the original article.

In the 22nd month of orthodontic treatment, in a radiographic routine examination, a circular and delimited radiolucent image was observed in the apical third of the root canal system of the maxillary right lateral incisor suggestive of IRR ( Fig 1 ). This alteration had not been noted on previous radiographic examinations, which were performed every 6 months. At the time the alternation was noted, the tooth showed pulp vitality in addition to similar responses to the left lateral incisor in clinical tests.

Fig 1
Periapical radiography of the maxillary right lateral incisor with image of the internal root resorption lesion 22 months after the beginning of orthodontic treatment.

The patient was informed about the lesion and (together with the orthodontist and endodontist) decided on clinical and radiographic monitoring without endodontic intervention. Periodic radiographic monitoring of the lesion (every 6 months) was done while orthodontic treatment was completed. Control periapical radiographies were performed 5 months ( Fig 2 , A ) and 11 months ( Fig 2 , B ) after the diagnosis of resorption, showing maintenance of the lesion contour and dimensions. Thirteen months after the diagnosis, the IRR lesion showed a reduction in size and lack of definition of its limits ( Fig 2 , C ), becoming less evident in the subsequent image at 21 months ( Fig 2 , D ).

Dec 24, 2021 | Posted by in Orthodontics | Comments Off on Spontaneous remission of internal root resorption during orthodontic treatment: A clinical follow-up report
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