in vivo 34 : 1875-1882 (2020) doi:10.21873/invivo.11983 Radiological and Histopathological Features of Internal Tooth Resorption TILL KOEHNE 1, JOZEF ZUSTIN 2, MICHAEL AMLING 2 and REINHARD E. FRIEDRICH 3 1Department of Orthodontics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; 2Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; 3Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany Abstract. Background: Internal root resorption is an hyperplasia and massive bacterial colonization. Conclusion: endodontic disease characterized by progressive resorption Our analyses demonstrate that internal root resorption is a of dentin from the inside of the pulp chamber. It is a multifaceted dental disease with considerable variability in comparatively rare finding in the permanent dentition, and the rate of the underlying inflammatory changes. Oral the underlying pathology is not fully understood. Case surgeons should take this into consideration when evaluating Report: A 45-year-old patient was referred to our the need for extraction of teeth with internal root resorption. Department for the evaluation of the lower right canine and the upper left wisdom tooth. Pulp sensitivity tests, cone-beam Resorption of calcified tissues, such as bone, dentin, and tomography, and magnetic resonance imaging were used to cementum, is a prerequisite for skeletal homeostasis and determine the extent of lesions of the affected teeth. The teeth tooth eruption. Resorption of permanent teeth, however, is a were subsequently extracted due the extent of the lesions. pathological condition that may result in the loss of the The same was the case for the upper right canine, which affected teeth. Tooth resorption can occur externally on the developed a severe internal resorption 10 months later. root surface or internally within the pulp chamber. External Micro-computed tomography of the extracted teeth revealed and internal tooth resorption should be considered as discrete that all lesions had a well-defined border with no evidence entities which differ in terms of prevalence and etiology. of sclerosis or hypomineralization. Pulp stones were evident External tooth resorption may affect up to 5% of all inside the pulp chamber. Ground sectioning of the upper permanent teeth, and it is usually caused by trauma, ectopic right canine revealed pulp necrosis and an acute infection teeth, or orthodontic tooth movement (1). In contrast, that had gradually moved in the apical direction. Large internal tooth resorption (IR) is a comparatively rare finding, multi-nucleated resorbing cells were found on the dentin and its etiology has not been fully elucidated (2). IR is surface. Importantly, the apical half of the pulp exhibited predominantly a lesion within the upper third of the pulp comparatively normal tissue without substantial chamber and may affect both the crown and the root of the inflammatory changes. Decalcified histology of the upper left tooth. The initial finding is resorption of the inner wall of wisdom tooth demonstrated a completely different the root canal that progresses in a centrifugal direction. histopathological appearance characterized by chronically Accompanying changes such as the resorption of the root inflamed granulation tissue with pseudoepitheliomatous surface or the alveolar bone may occur, but are not mandatory findings in IR. In fact, the diagnosis of IR can only be made if external factors such as root caries or cervical resorptions can be excluded. This article is freely accessible online. There are several studies describing radiological and histological features of teeth with IR (3-7). However, some Correspondence to: Dr. Till Koehne, DMD, Ph.D., Department of of these reports need to be interpreted with caution, since Orthodontics, University Medical Center Hamburg-Eppendorf, they were based on two-dimensional radiographs, where Martinistr. 52, 20246 Hamburg, Germany. Tel: +49 40741054398, internal and external resorption can often not be clearly Fax: +49 40741054887, e-mail: [email protected] distinguished. Moreover, only a few reports performed a Key Words: Magnetic resonance imaging, cone beam computed thorough histological analysis. tomography, micro-computed tomography, pulp histology, pulp The aim of this study of a case was therefore to describe inflammation, internal root resorption. three-dimensional radiographic characteristics of teeth with 1875 in vivo 34 : 1875-1882 (2020) Figure 1. Cone-beam computed tomography. Reconstructed views (sagittal, axial, and coronal) demonstrating large, well-defined radiolucencies within the pulp chambers of the upper left wisdom tooth (A-C) and the lower right canine (D-F). Note that at this time point, there was only a small lateral lesion of the upper right canine (G-I), which might also be an artifact. IR using cone-beam tomography (CBCT), magnetic The oral examination revealed that the lower first and resonance imaging (MRI), and micro-computed second molars, as well as the lower left first bicuspid, were tomography (micro-CT). In addition, we performed missing. Pulp sensitivity tests (Henry Schein, Langen, decalcified histology and ground sectioning to describe the Germany) produced no response from the lower right different histopathological stages of IR. canine and the upper left wisdom tooth, whilst all other teeth responded to cold without lingering. No caries were Case Report clinically detected. CBCT was performed using a CBCT scanner (3D A 45-year-old man was referred to the Department of Oral Accuitomo 170, MCT-1 EX-1 F17; Morita MFG Corp., and Maxillofacial Surgery, University Medical Center Kyoto, Japan). Imaging was carried out with an exposure Hamburg-Eppendorf, for evaluation of resorption of the time of 18 seconds (360˚), slice thickness of 1 mm, voxel lower right canine and the upper left wisdom tooth. The size of 80-250 μm, and exposure volume of 170×120 mm. medical history was non-contributory. A review of the dental CBCT of the jaws indicated resorption within the lower right history revealed that the patient had been involved in an canine and upper left wisdom teeth that were connected to assault about 15 years earlier that resulted in a fracture of the surrounding periodontal ligament ( Figure 1 A-F). The the upper left central incisor. The tooth had been restored by upper right canine, which was also later affected by IR, was a general dentist. unremarkable at this stage (Figure 1G-I). 1876 Koehne et al : Study on Internal Tooth Resorption Figure 2. Magnetic resonance imaging. Axial T2-weighted images of the upper (A-C) and lower (D-F) jaws revealed abnormal high signal intensity inside the upper left wisdom tooth and the lower right canine. The regions marked by the white rectangles in B and E are shown at higher magnifications in C and F, respectively. MRI has proven to be a sensitive method for detecting wisdom tooth were indicated. Patient consent was obtained changes in pulp vascularization (8). It was therefore used to after a comprehensive discussion of the complications and examine the vascularization of the diseased teeth and to risks of surgical treatment and the need for prosthetic exclude a general disorder of pulp vascularization ( Figure 2 ). rehabilitation. The healthy, vital teeth produced a slightly hyperintense signal The extraction of both teeth was performed under local of threadlike (coronal or sagittal section) or point-like (axial anesthesia without complication, although the teeth fractured. section) shape, which was homogeneously surrounded by a A partial ankylosis of the lower right canine was noted. A non-stimulated (black) region identified as the dental hard part of the pulp and the surrounding periodontal tissue were tissues. MRI signals of the pulp at the site of the IR differed preserved for histological analysis. The healing of the from the control teeth both in shape and intensity. In the axial wounds was uneventful. Ten months later, the patient cross-section, the hyperintense signal was present in almost returned to the Outpatient Department for evaluation of large the entire crown area. The signal was significantly more IR within the upper right canine. The tooth was considered intense in the area of the inflammatory pulp as compared to as not worth preserving after the evaluation of a radiograph those of the vital teeth. Irregularly distributed hypointense performed by the patient’s general dentist (not shown). The signals were present within these hyperintense regions. The IR extraction of the tooth was performed under local anesthesia lesions were also hyperintense in short-tau inversion recovery, without complication. It was possible to extract the tooth in and T1- and T2-weighted sequences, and gave positive signals one piece. A lateral perforation at the cervix was noted in diffusion-weighted whole-body imaging with background (Figure 3 A). body signal suppression (data not shown). The extracted teeth were fixed in 3.7% phosphate-buffered Due to the extent of the lesions and the perforation, saline-buffered formaldehyde. Contact radiography extraction of the lower right canine and the upper left (Faxitron ® MX-20, Faxitron Bioptics, Hennef, Germany) of 1877 in vivo 34 : 1875-1882 (2020) Figure 3. Ex-vivo specimens imaging. Photography (A) and contact radiography (B) of the upper right canine. A small perforation is evident at the tooth cervix (arrow). Micro-computed tomography of all extracted teeth