- Email: [email protected]
Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor
pediatric dental journal xxx (xxxx) xxx
Available online at www.sciencedirect.com
Pediatric Dental Journal journal homepage: www.elsevier.com/locate/pdj
Case Report
Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor Masako Toda Nakamura a, Kyoko Oka a,*, Hana Harada a, Kayoko Ogata b, Satoru Matsuo a, Mihoko Rikitake a, Shirabe Ohki a, Tetsuya Kumagai a, Yoko Kato c, Atsuko Baba a, Masao Ozaki a a
Section of Pediatric Dentistry, Department of Oral Growth and Development, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka, 814-0193, Japan b Section of Functional Structure, Department of Morphological Biology, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka, 814-0193, Japan c Kato Dental Office for Children, Sawara-ku, Fukuoka, Japan
article info
abstract
Article history:
A girl attended our clinic with inflammation of the marginal gingiva. The surfaces of
Received 21 June 2019
central incisors had severe enamel defects caused by trauma to the primary incisors.
Received in revised form
Swollen but non-ulcerated gingiva was present on the surface of the left central incisor.
3 October 2019
The gingival mass was surgically removed. Immunohistochemical analyses revealed that
Accepted 10 November 2019
the resected mass included epithelial tissue expressing odontogenic ameloblast-associated
Available online xxx
protein (ODAM), which is a marker of junctional epithelium. It was likely ectopic junctional epithelium that had formed due to disorganization of the enamel organ during develop-
Keywords: Epulis granulomatosa
ment caused by dental trauma to the primary incisors. © 2020 Published by Elsevier Ltd on behalf of Japanese Society of Pediatric Dentistry.
Junctional epithelium ODAM
1.
Introduction
Dental trauma to primary teeth often affects the development of the successor permanent teeth resulting in dislocation, delayed eruption and enamel hypoplasia [[1]]. Therefore, dental trauma to a primary tooth necessitates careful monitoring until normal eruption of the permanent successor tooth is observed. Here we report a case of a central incisor with enamel hypoplasia and ectopic adhesion of gingival
epithelium, which had developed after dental trauma to the primary incisors. Although the histopathological diagnosis was epulis granulomatosa, the adhered gingival tissue was not typical of an epulis mass on clinical examination, and it was hardly tear off crown surface with enamel defect. Therefore, we hypothesized that this ectopic gingiva included junctional epithelium (JE) as one of its components. Generally, gingival epithelium is classified into gingival oral epithelium, sulcular epithelium and JE. JE exhibits a specialized epithelial structure known as the dento-gingival
* Corresponding author. E-mail address: [email protected] (K. Oka). https://doi.org/10.1016/j.pdj.2019.11.002 0917-2394/© 2020 Published by Elsevier Ltd on behalf of Japanese Society of Pediatric Dentistry. Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
2
pediatric dental journal xxx (xxxx) xxx
unit that adheres to the cervical region of an erupted tooth [2]. Initially, the primary JE is formed by fusion of the reduced enamel organ and connective tissue during the crown stage of development and is composed of reduced ameloblasts and papillary cells [3]. Therefore, JE could form ectopically if the enamel organ becomes disorganized by traumatic force during the crown stage of development. Odontogenic ameloblast-associated protein (ODAM) has been reported to be a marker of JE [4]. ODAM was originally cloned from the human KATO III cell line [5] and has been detected in calcifying epithelial odontogenic tumorassociated amyloid [6]. ODAM expression in ameloblasts is first observed during the transition stage of ameloblast differentiation and is further detected in the supranuclear region and at the ameloblast-enamel layer interface during the maturation stage [7]. During JE regeneration in animal experiments using rat, ODAM is detected first at the leading wound edge and then in the regenerating JE [8,9]. In the present case, we performed immunohistochemical analyses using various differentiation markers, including Cytokeratin-14 for epithelium, Periostin for periodontal ligament and ODAM for JE, to obtain a histopathological diagnosis and better understand the potential mechanism underlying the ectopic formation of gingival tissue that was adhered to the crown surface.
2.
Case report
A Japanese girl aged 7 years and 4 months was referred by a local pediatric dentistry practitioner to our pediatric dentistry department for consultation regarding inflammation and irregularity of the marginal gingiva of the left maxillary central incisor. The Hellman dental age was IIIA, and the surfaces of both central incisors had severe enamel defects (Fig. 1c and f). Swollen but non-ulcerated gingiva was observed on the surface of the left central incisor (Fig. 1f, arrow). Air blowing caused sharp pain in the left central incisor. The dental record described severe dental trauma at the age of 3 years and treatment for necrotic maxillary primary central incisors, which were eventually extracted because of
apical periodontitis. After eruption, the maxillary permanent central incisors showed enamel hypoplasia and responded to air or cold water with sharp pain. Dental x-ray imaging showed immature root formation and a line of low x-ray attenuation in the crown region with uneven crown shape (Fig. 2a). In cone-beam computed tomography (CBCT) images, the enamel layer lining the incisor crowns was observed discontinuously on the buccal surface of the maxillary incisors (Fig. 2b and c, arrowhead). The CT value of this buccal surface was variable, lower than that of normal enamel and comparable to that of dentin (Fig. 2b and c, arrowhead). The ectopic gingiva was surgically removed from the crown under local anesthesia (Fig. 3a and b), and the biopsy sample was sent for histopathological analysis. The region of enamel hypoplasia was repaired using composite resin (Fig. 3c). Follow-up observations were conducted at 1 month (Fig. 3d and e) and 6 months (Fig. 3f and g), and no notable clinical problems have arisen during the 2 years since treatment.
3.
Histopathology
The biopsy sample was stored in 10% formalin and embedded in paraffin without decalcification, processed for histological analyses based on hematoxylin/eosin (HE) staining and immunohistochemistry (Fig. 4). Rabbit antiODAM polyclonal antibody (Abcam Japan, Tokyo, Japan), mouse anti-cytokeratin-14 polyclonal antibody (Proteintech Japan, Tokyo, Japan) and rabbit anti-periostin polyclonal antibody (Abcam Japan, Tokyo, Japan) were diluted 1:100 and used as the primary antibodies for the immunohistochemical analysis. Secondary antibody, biotin-conjugated goat anti-mouse/rabbit immunoglobulin G (IgG) was diluted 1:100. The specimens were sensitized using streptavidin peroxidase (Vector Laboratories, Burlingame, CA, USA) and visualized using a DAB kit (Nichirei Biosciences, Inc.,Tokyo, Japan). It was performed using a secondary antibody only (no primary antibody) as negative control. It was examined no visual background.
Fig. 1 e Intraoral images obtained in a girl aged 7 years and 4 months. (a, b) Occlusal views of the maxillary and mandibular arch. (c) Frontal view in occlusion. (d, e) Lateral buccal view in occlusion. (f) Higher-magnification view of the buccal surface of the maxillary central incisor. Arrow indicates the region of swollen gingiva. Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
pediatric dental journal xxx (xxxx) xxx
3
Fig. 2 e X-ray and cone-beam computed tomography (CBCT) images of the left maxillary central incisor. (a) Oral x-ray image showing immature root formation and a line of low x-ray attenuation (arrow) in the crown. (b, c) CBCT images showing occlusal and sagittal views. (d) Three-dimensional reconstruction of the left maxillary central incisor. Arrowhead displays a discontinuous region in the calcified enamel surface.
Fig. 3 e Treatment and sequential observations of the left maxillary central incisor. (a) Surgical removal of the ectopic gingiva. (b) The buccal surface after removal of the ectopic gingiva. (c) The buccal surface after restoration with resin. (d, e) Oral photographs and x-ray images obtained one month after treatment. (f, g) Oral photographs and x-ray images obtained six months after treatment.
Fig. 4 e Histological findings following staining with hematoxylin/eosin (HE) or immunohistochemistry (IHC). (a, e) HEstained section showing granulation tissue with infiltration of inflammatory lymphocytes. (b, f) Immunohistochemical analysis of cytokeratin-14 expression. (c, g) Immunohistochemical analysis of periostin expression. (d, h) Immunohistochemical analysis of odontogenic ameloblast-associated protein (ODAM) expression. (e), (f), (g) and (h) show higher-magnification views of the dotted squares in (a), (b), (c) and (d), respectively. Scale bars: 300 mm. Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
4
pediatric dental journal xxx (xxxx) xxx
In HE-stained sections, the surface layer of the mass was covered with stratified squamous epithelium (Fig. 4a and e), and the mesenchymal tissue contained fibrous connective tissue and blood vessels with extensive infiltration of chronic inflammatory cells. A histopathological diagnosis of epulis granulomatosa was made based on the HE-stained sections. However, the cervical region of the mass was not a typical epulis on clinical examination because it was not derived from the gingiva but instead was adhered to the buccal surface of an incisor crown. Therefore, immunostaining was performed to further characterize the resected tissue. Cytokeratin-14 expression was observed not only in the hypertrophic stratified squamous epithelium on the surface of the mass but also in the cervical region that had been adhered to the crown surface (Fig. 4b and f). Periostin expression was observed in the region adjacent to the epithelial tissue (Fig. 4c and g). Interestingly, ODAM was strongly expressed only in the region of epithelium that had adhered to the crown (Fig. 4d and h). Since ODAM is a marker of junctional epithelial cells, these results indicate that ectopic JE was a component present in the cervical region of the mass that had been attached to the crown.
The enamel surface during crown formation is covered by the reduced enamel epithelium, which consists of reduced ameloblasts and cells remaining from the other aligned layers of the enamel organ. The JE originates from the reduced enamel epithelium prior to the emergence of the tooth into the oral cavity. Therefore, it is possible that intrinsic or extrinsic factors could cause ectopic formation of JE during tooth development. The patient described in this case report had initially experienced dental trauma to the primary central incisor when she was three years old. We propose that the epithelium of the enamel organ in the permanent central incisor was physically damaged during this incident, which subsequently triggered enamel hypoplasia. Furthermore, damaged reduced enamel epithelium likely resulted in the ectopic formation of JE in the left central incisor. The patient exhibited a good recovery after restorative treatment of the enamel hypoplasia. The JE reformed and adhered to the tooth surface. However, an accurate diagnosis was obtained only after the examination of HE-stained tissue and use of an immunohistochemical analysis.
5. 4.
Conclusion
Discussion
The clinical definition of an epulis is hyperplasia of the gum predominantly situated at an interdental papilla region. An epulis generally originates from the periodontium and periosteum and is most commonly found in elderly patients with a female preponderance [10]. In the current case, the pathological diagnosis based on HE staining was epulis granulomatosa. However, since epulis is a purely clinical term and does not reflect the histopathological diversity of the lesions, we performed immunohistochemical analyses to further characterize the resected gingival tissue. An epulis is generally found in connective tissues such as gums, alveolar prostheses and the periodontal membrane [10]. However, in the current case, the cervical (lower) region of the mass was strongly attached to the surface of the crown of an incisor. Therefore, we hypothesized that the cervical region of this mass might include a component found in the enamel organ of incisor tooth germ such as JE. JE is found in the cervical region of the tooth crown and is crucial for maintaining periodontal health against microorganisms and their products during eruption of the crown. The innermost cells of the JE form and maintain a tight seal against the mineralized tooth surface, which is known as the epithelial attachment [11]. ODAM has been implicated in diverse processes such as ameloblast differentiation, enamel maturation and tumor growth (7). ODAM expression emerges during the developmental continuum between ameloblast maturation and formation of normal JE but is reduced after damage to the JE (9). Therefore, we performed an immunohistochemical analysis of the resected mass to determine ODAM expression in the current case. We detected clear ODAM expression in the cervical region of the mass that had been attached to the crown surface. Thus, we conclude that ectopic JE had formed and adhered to the buccal surface of the crown during eruption of the left maxillary incisor.
We have presented a rare case of an epulis on the buccal enamel surface of a crown. Abnormal formation of gingiva was observed on a central incisor that was affected during its development by dental trauma to the primary incisor. The gingiva was integrated into the buccal crown surface, which showed enamel hypoplasia. ODAM, a marker of JE, was clearly expressed in the region of the dissected gingiva that had been attached to the tooth crown. We conclude that the ectopic formation of JE in this case was due to the disorganized formation of gingival tissue caused by dental trauma to the primary incisor.
Declaration of Competing Interest The authors declare that there is no conflict of interest regarding the publication of this article.
Acknowledgement For the presentation of this case, informed consent was given to the patient’s parents and Written and verbal consent was obtained. This study was supported in part by Grant-in-Aid for Young Scientists B (No. 17K17344 to MN) from the Japan Society for the Promotion of Science (JSPS). The authors thank OXMEDCOMMS (www.oxmedcomms. com) for writing assistance.
references
[1] Bardellini E, Amadori F, Pasini S, Majorana A. Dental anomalies in permanent teeth after trauma in primary dentition. J Clin Pediatr Dent 2017;41(1):5e9.
Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
pediatric dental journal xxx (xxxx) xxx
[2] Schroeder HE, Listgarten MA. The gingival tissues: the architecture of periodontal protection. Periodontol 2000 1997;13:91e120. [3] Ten Cate AR. Development of the periodontium. In: Ten Cate AR, editor. Oral histology. Development, structure, and function. St. Louis: Mosby; 1998. p. 236e52. [4] Lee HK, Park SJ, Oh HJ, Kim JW, Bae HS, Park JC. Expression pattern, subcellular localization, and functional implications of ODAM in ameloblasts, odontoblasts, osteoblasts, and various cancer cells. Gene Expr Patterns 2012;12(3e4):102e8. [5] Sekiguchi M, Sakakibara K, Fujii G. Establishment of cultured cell lines derived from a human gastric carcinoma. Jpn J Exp Med 1978;48(1):61e8. [6] Solomon A, Murphy CL, Weaver K, Weiss DT, Hrncic R, Eulitz M, et al. Calcifying epithelial odontogenic (Pindborg) tumor-associated amyloid consists of a novel human protein. J Lab Clin Med 2003;142(5):348e55. [7] Lee HK, Lee DS, Ryoo HM, Park JT, Park SJ, Bae HS, et al. The odontogenic ameloblast-associated protein (ODAM)
[8]
[9]
[10]
[11]
5
cooperates with RUNX2 and modulates enamel mineralization via regulation of MMP-20. J Cell Biochem 2010;111(3):755e67. Nishio C, Wazen R, Moffatt P, Nanci A. Expression of odontogenic ameloblast-associated and amelotin proteins in the junctional epithelium. Periodontol 2000 2013;63(1):59e66. Nishio C, Wazen R, Kuroda S, Moffatt P, Nanci A. Expression pattern of odontogenic ameloblast-associated and amelotin during formation and regeneration of the junctional epithelium. Eur Cells Mater 2010;20:393e402. Truschnegg A, Acham S, Kiefer BA, Jakse N, Beham A. Epulis: a study of 92 cases with special emphasis on histopathological diagnosis and associated clinical data. Clin Oral Investig 2016;20(7):1757e64. Schroeder HE. Histopathology of the gingival sulcus. In: Lehner T, editor. The borderland between caries and periodontal disease. London: Academic Press; 1977. p. 43e78.
Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
Available online at www.sciencedirect.com
Pediatric Dental Journal journal homepage: www.elsevier.com/locate/pdj
Case Report
Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor Masako Toda Nakamura a, Kyoko Oka a,*, Hana Harada a, Kayoko Ogata b, Satoru Matsuo a, Mihoko Rikitake a, Shirabe Ohki a, Tetsuya Kumagai a, Yoko Kato c, Atsuko Baba a, Masao Ozaki a a
Section of Pediatric Dentistry, Department of Oral Growth and Development, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka, 814-0193, Japan b Section of Functional Structure, Department of Morphological Biology, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka, 814-0193, Japan c Kato Dental Office for Children, Sawara-ku, Fukuoka, Japan
article info
abstract
Article history:
A girl attended our clinic with inflammation of the marginal gingiva. The surfaces of
Received 21 June 2019
central incisors had severe enamel defects caused by trauma to the primary incisors.
Received in revised form
Swollen but non-ulcerated gingiva was present on the surface of the left central incisor.
3 October 2019
The gingival mass was surgically removed. Immunohistochemical analyses revealed that
Accepted 10 November 2019
the resected mass included epithelial tissue expressing odontogenic ameloblast-associated
Available online xxx
protein (ODAM), which is a marker of junctional epithelium. It was likely ectopic junctional epithelium that had formed due to disorganization of the enamel organ during develop-
Keywords: Epulis granulomatosa
ment caused by dental trauma to the primary incisors. © 2020 Published by Elsevier Ltd on behalf of Japanese Society of Pediatric Dentistry.
Junctional epithelium ODAM
1.
Introduction
Dental trauma to primary teeth often affects the development of the successor permanent teeth resulting in dislocation, delayed eruption and enamel hypoplasia [[1]]. Therefore, dental trauma to a primary tooth necessitates careful monitoring until normal eruption of the permanent successor tooth is observed. Here we report a case of a central incisor with enamel hypoplasia and ectopic adhesion of gingival
epithelium, which had developed after dental trauma to the primary incisors. Although the histopathological diagnosis was epulis granulomatosa, the adhered gingival tissue was not typical of an epulis mass on clinical examination, and it was hardly tear off crown surface with enamel defect. Therefore, we hypothesized that this ectopic gingiva included junctional epithelium (JE) as one of its components. Generally, gingival epithelium is classified into gingival oral epithelium, sulcular epithelium and JE. JE exhibits a specialized epithelial structure known as the dento-gingival
* Corresponding author. E-mail address: [email protected] (K. Oka). https://doi.org/10.1016/j.pdj.2019.11.002 0917-2394/© 2020 Published by Elsevier Ltd on behalf of Japanese Society of Pediatric Dentistry. Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
2
pediatric dental journal xxx (xxxx) xxx
unit that adheres to the cervical region of an erupted tooth [2]. Initially, the primary JE is formed by fusion of the reduced enamel organ and connective tissue during the crown stage of development and is composed of reduced ameloblasts and papillary cells [3]. Therefore, JE could form ectopically if the enamel organ becomes disorganized by traumatic force during the crown stage of development. Odontogenic ameloblast-associated protein (ODAM) has been reported to be a marker of JE [4]. ODAM was originally cloned from the human KATO III cell line [5] and has been detected in calcifying epithelial odontogenic tumorassociated amyloid [6]. ODAM expression in ameloblasts is first observed during the transition stage of ameloblast differentiation and is further detected in the supranuclear region and at the ameloblast-enamel layer interface during the maturation stage [7]. During JE regeneration in animal experiments using rat, ODAM is detected first at the leading wound edge and then in the regenerating JE [8,9]. In the present case, we performed immunohistochemical analyses using various differentiation markers, including Cytokeratin-14 for epithelium, Periostin for periodontal ligament and ODAM for JE, to obtain a histopathological diagnosis and better understand the potential mechanism underlying the ectopic formation of gingival tissue that was adhered to the crown surface.
2.
Case report
A Japanese girl aged 7 years and 4 months was referred by a local pediatric dentistry practitioner to our pediatric dentistry department for consultation regarding inflammation and irregularity of the marginal gingiva of the left maxillary central incisor. The Hellman dental age was IIIA, and the surfaces of both central incisors had severe enamel defects (Fig. 1c and f). Swollen but non-ulcerated gingiva was observed on the surface of the left central incisor (Fig. 1f, arrow). Air blowing caused sharp pain in the left central incisor. The dental record described severe dental trauma at the age of 3 years and treatment for necrotic maxillary primary central incisors, which were eventually extracted because of
apical periodontitis. After eruption, the maxillary permanent central incisors showed enamel hypoplasia and responded to air or cold water with sharp pain. Dental x-ray imaging showed immature root formation and a line of low x-ray attenuation in the crown region with uneven crown shape (Fig. 2a). In cone-beam computed tomography (CBCT) images, the enamel layer lining the incisor crowns was observed discontinuously on the buccal surface of the maxillary incisors (Fig. 2b and c, arrowhead). The CT value of this buccal surface was variable, lower than that of normal enamel and comparable to that of dentin (Fig. 2b and c, arrowhead). The ectopic gingiva was surgically removed from the crown under local anesthesia (Fig. 3a and b), and the biopsy sample was sent for histopathological analysis. The region of enamel hypoplasia was repaired using composite resin (Fig. 3c). Follow-up observations were conducted at 1 month (Fig. 3d and e) and 6 months (Fig. 3f and g), and no notable clinical problems have arisen during the 2 years since treatment.
3.
Histopathology
The biopsy sample was stored in 10% formalin and embedded in paraffin without decalcification, processed for histological analyses based on hematoxylin/eosin (HE) staining and immunohistochemistry (Fig. 4). Rabbit antiODAM polyclonal antibody (Abcam Japan, Tokyo, Japan), mouse anti-cytokeratin-14 polyclonal antibody (Proteintech Japan, Tokyo, Japan) and rabbit anti-periostin polyclonal antibody (Abcam Japan, Tokyo, Japan) were diluted 1:100 and used as the primary antibodies for the immunohistochemical analysis. Secondary antibody, biotin-conjugated goat anti-mouse/rabbit immunoglobulin G (IgG) was diluted 1:100. The specimens were sensitized using streptavidin peroxidase (Vector Laboratories, Burlingame, CA, USA) and visualized using a DAB kit (Nichirei Biosciences, Inc.,Tokyo, Japan). It was performed using a secondary antibody only (no primary antibody) as negative control. It was examined no visual background.
Fig. 1 e Intraoral images obtained in a girl aged 7 years and 4 months. (a, b) Occlusal views of the maxillary and mandibular arch. (c) Frontal view in occlusion. (d, e) Lateral buccal view in occlusion. (f) Higher-magnification view of the buccal surface of the maxillary central incisor. Arrow indicates the region of swollen gingiva. Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
pediatric dental journal xxx (xxxx) xxx
3
Fig. 2 e X-ray and cone-beam computed tomography (CBCT) images of the left maxillary central incisor. (a) Oral x-ray image showing immature root formation and a line of low x-ray attenuation (arrow) in the crown. (b, c) CBCT images showing occlusal and sagittal views. (d) Three-dimensional reconstruction of the left maxillary central incisor. Arrowhead displays a discontinuous region in the calcified enamel surface.
Fig. 3 e Treatment and sequential observations of the left maxillary central incisor. (a) Surgical removal of the ectopic gingiva. (b) The buccal surface after removal of the ectopic gingiva. (c) The buccal surface after restoration with resin. (d, e) Oral photographs and x-ray images obtained one month after treatment. (f, g) Oral photographs and x-ray images obtained six months after treatment.
Fig. 4 e Histological findings following staining with hematoxylin/eosin (HE) or immunohistochemistry (IHC). (a, e) HEstained section showing granulation tissue with infiltration of inflammatory lymphocytes. (b, f) Immunohistochemical analysis of cytokeratin-14 expression. (c, g) Immunohistochemical analysis of periostin expression. (d, h) Immunohistochemical analysis of odontogenic ameloblast-associated protein (ODAM) expression. (e), (f), (g) and (h) show higher-magnification views of the dotted squares in (a), (b), (c) and (d), respectively. Scale bars: 300 mm. Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
4
pediatric dental journal xxx (xxxx) xxx
In HE-stained sections, the surface layer of the mass was covered with stratified squamous epithelium (Fig. 4a and e), and the mesenchymal tissue contained fibrous connective tissue and blood vessels with extensive infiltration of chronic inflammatory cells. A histopathological diagnosis of epulis granulomatosa was made based on the HE-stained sections. However, the cervical region of the mass was not a typical epulis on clinical examination because it was not derived from the gingiva but instead was adhered to the buccal surface of an incisor crown. Therefore, immunostaining was performed to further characterize the resected tissue. Cytokeratin-14 expression was observed not only in the hypertrophic stratified squamous epithelium on the surface of the mass but also in the cervical region that had been adhered to the crown surface (Fig. 4b and f). Periostin expression was observed in the region adjacent to the epithelial tissue (Fig. 4c and g). Interestingly, ODAM was strongly expressed only in the region of epithelium that had adhered to the crown (Fig. 4d and h). Since ODAM is a marker of junctional epithelial cells, these results indicate that ectopic JE was a component present in the cervical region of the mass that had been attached to the crown.
The enamel surface during crown formation is covered by the reduced enamel epithelium, which consists of reduced ameloblasts and cells remaining from the other aligned layers of the enamel organ. The JE originates from the reduced enamel epithelium prior to the emergence of the tooth into the oral cavity. Therefore, it is possible that intrinsic or extrinsic factors could cause ectopic formation of JE during tooth development. The patient described in this case report had initially experienced dental trauma to the primary central incisor when she was three years old. We propose that the epithelium of the enamel organ in the permanent central incisor was physically damaged during this incident, which subsequently triggered enamel hypoplasia. Furthermore, damaged reduced enamel epithelium likely resulted in the ectopic formation of JE in the left central incisor. The patient exhibited a good recovery after restorative treatment of the enamel hypoplasia. The JE reformed and adhered to the tooth surface. However, an accurate diagnosis was obtained only after the examination of HE-stained tissue and use of an immunohistochemical analysis.
5. 4.
Conclusion
Discussion
The clinical definition of an epulis is hyperplasia of the gum predominantly situated at an interdental papilla region. An epulis generally originates from the periodontium and periosteum and is most commonly found in elderly patients with a female preponderance [10]. In the current case, the pathological diagnosis based on HE staining was epulis granulomatosa. However, since epulis is a purely clinical term and does not reflect the histopathological diversity of the lesions, we performed immunohistochemical analyses to further characterize the resected gingival tissue. An epulis is generally found in connective tissues such as gums, alveolar prostheses and the periodontal membrane [10]. However, in the current case, the cervical (lower) region of the mass was strongly attached to the surface of the crown of an incisor. Therefore, we hypothesized that the cervical region of this mass might include a component found in the enamel organ of incisor tooth germ such as JE. JE is found in the cervical region of the tooth crown and is crucial for maintaining periodontal health against microorganisms and their products during eruption of the crown. The innermost cells of the JE form and maintain a tight seal against the mineralized tooth surface, which is known as the epithelial attachment [11]. ODAM has been implicated in diverse processes such as ameloblast differentiation, enamel maturation and tumor growth (7). ODAM expression emerges during the developmental continuum between ameloblast maturation and formation of normal JE but is reduced after damage to the JE (9). Therefore, we performed an immunohistochemical analysis of the resected mass to determine ODAM expression in the current case. We detected clear ODAM expression in the cervical region of the mass that had been attached to the crown surface. Thus, we conclude that ectopic JE had formed and adhered to the buccal surface of the crown during eruption of the left maxillary incisor.
We have presented a rare case of an epulis on the buccal enamel surface of a crown. Abnormal formation of gingiva was observed on a central incisor that was affected during its development by dental trauma to the primary incisor. The gingiva was integrated into the buccal crown surface, which showed enamel hypoplasia. ODAM, a marker of JE, was clearly expressed in the region of the dissected gingiva that had been attached to the tooth crown. We conclude that the ectopic formation of JE in this case was due to the disorganized formation of gingival tissue caused by dental trauma to the primary incisor.
Declaration of Competing Interest The authors declare that there is no conflict of interest regarding the publication of this article.
Acknowledgement For the presentation of this case, informed consent was given to the patient’s parents and Written and verbal consent was obtained. This study was supported in part by Grant-in-Aid for Young Scientists B (No. 17K17344 to MN) from the Japan Society for the Promotion of Science (JSPS). The authors thank OXMEDCOMMS (www.oxmedcomms. com) for writing assistance.
references
[1] Bardellini E, Amadori F, Pasini S, Majorana A. Dental anomalies in permanent teeth after trauma in primary dentition. J Clin Pediatr Dent 2017;41(1):5e9.
Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002
pediatric dental journal xxx (xxxx) xxx
[2] Schroeder HE, Listgarten MA. The gingival tissues: the architecture of periodontal protection. Periodontol 2000 1997;13:91e120. [3] Ten Cate AR. Development of the periodontium. In: Ten Cate AR, editor. Oral histology. Development, structure, and function. St. Louis: Mosby; 1998. p. 236e52. [4] Lee HK, Park SJ, Oh HJ, Kim JW, Bae HS, Park JC. Expression pattern, subcellular localization, and functional implications of ODAM in ameloblasts, odontoblasts, osteoblasts, and various cancer cells. Gene Expr Patterns 2012;12(3e4):102e8. [5] Sekiguchi M, Sakakibara K, Fujii G. Establishment of cultured cell lines derived from a human gastric carcinoma. Jpn J Exp Med 1978;48(1):61e8. [6] Solomon A, Murphy CL, Weaver K, Weiss DT, Hrncic R, Eulitz M, et al. Calcifying epithelial odontogenic (Pindborg) tumor-associated amyloid consists of a novel human protein. J Lab Clin Med 2003;142(5):348e55. [7] Lee HK, Lee DS, Ryoo HM, Park JT, Park SJ, Bae HS, et al. The odontogenic ameloblast-associated protein (ODAM)
[8]
[9]
[10]
[11]
5
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Please cite this article as: Nakamura MT et al., Ectopic junctional epithelium adhered to the buccal crown surface of an upper central incisor, Pediatric Dental Journal, https://doi.org/10.1016/j.pdj.2019.11.002