Int J Stomatol

Int J Stomatol ›› 2025, Vol. 52 ›› Issue (6): 713-721.doi: 10.7518/gjkq.2025098

• Cariology and Endodontics • Previous Articles     Next Articles

The formation mechanism, clinical diagnosis, and treatment strategies of ectopic enamel

Shiya Wang1(),Guohua Yuan2,Jing Zou1()   

  1. 1.State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Dept. of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
    2.State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Dept. of Pediatric Dentistry, School & Hospital of Stomatology, Wuhan University, Wuhan 430079, China
  • Received:2024-08-20 Revised:2025-07-07 Online:2025-11-01 Published:2025-10-23
  • Contact: Jing Zou E-mail:wangshiya@stu.scu.edu.cn;zoujing@scu.edu.cn
  • Supported by:
    National Natural Science Foundation of China(82170947)

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Abstract:

Ectopic enamel is a type of abnormal dental development, which can be divided into two categories: enamel pearls and cervical enamel projections. The formation of ectopic enamel may be related to ameloblasts in the Hertwig’s epithelial root sheath and Malassez epithelial rest. Mechanical and genetic factors may also play a role in the formation of ectopic enamel. Radiographic examination can identify ectopic enamel, assess its condition, and guide clinical diagnosis and treatment. This article reviews the clinical characteristics, formation mechanisms, diagnosis, and treatment strategies of ectopic enamel to provide references and a clinical basis for its diagnosis and treatment.

Key words: ectopic enamel, enamel pearl, cervical enamel projections, periodontitis

CLC Number: 

  • R322.4+1

TrendMD: 

Tab 1

Summary of differences in characteristics between enamel pearls and CEPs"

特征釉珠CEP
定义牙根表面釉质的异常沉积釉质在CEJ的根方异位沉积，呈指状突起
分类根据结构不同分为釉质型釉珠、釉质-牙本质型釉珠、釉质-牙本质-牙髓型釉珠；根据部位不同分为外在性釉珠和内在性釉珠Ⅰ类：指向根分叉方向延伸至CEJ下方；Ⅱ类：比Ⅰ类更靠近但未到达根分叉区；Ⅲ类：进入根分叉内部
发生率各研究差异大，多为1.1%~5.7%总体发生率变异大，从8.3%~45.2%
发生牙位上颌磨牙根部多见，尤其是上颌第三磨牙下颌磨牙多见，尤其是第一、第二磨牙
形态球形、圆锥形、卵形、泪滴形、不规则形漏斗状，底部与牙冠釉质相延续
微观结构棱柱形，不规则区域主要在牙颈部；存在Retzius条纹、Hunter-Schreger条纹钙和磷酸盐含量较低，矿化程度低；结构缺陷，有扭曲的棱柱和不规则的间隔条纹
显微硬度大釉珠与冠部釉质相近；小釉珠显著低于冠部釉质

Tab 2

Differences in characteristics between external enamel pearls and internal enamel pearls"

特征外在性釉珠内在性釉珠
发病率较低罕见
位置上颌磨牙多见磨牙、前磨牙、尖牙均可发生
发生部位主要出现在根分叉区域多出现于冠部牙本质内
起源可能来源于Hertwig上皮根鞘和Malassez上皮剩余可能来源于釉结、颈环或内釉上皮

Fig 1

Classification of CEPs"

Fig 2

Mechanism of ectopic enamel formation"

Fig 3

The influence of mechanical factors on ectopic enamel"

Fig 4

Mechanism of internal enamel pearls formation"

[1] Marsico C, Grimm JR, Renteria C, et al. Characte-rizing the microstructures of mammalian enamel by synchrotron phase contrast microCT[J]. Acta Biomater, 2024, 178: 208-220.
[2] Wei R, Guo S, Meng Z, et al. Mediator1 involved in functional integration of Smad3 and Notch1 promo-ting enamel mineralization[J]. Biochem Biophys Res Commun, 2023, 663: 47-53.
[3] Saini T, Ogunleye A, Levering N, et al. Multiple enamel pearls in two siblings detected by volume-tric computed tomography[J]. Dentomaxillofac Radiol, 2008, 37(4): 240-244.
[4] Grine FE, Holt S, Brink JS, et al. Enamel pearls: their occurrence in recent human populations and earliest manifestation in the modern human lineage[J]. Arch Oral Biol, 2019, 101: 147-155.
[5] Zengin AZ, Sumer AP, Ozturk G, et al. Imaging characteristics of enamel pearls on CBCT and their co-relation with supernumerary tooth[J]. Oral Ra-diol, 2022, 38(3): 370-377.
[6] Cavanha AO. Enamel pearls[J]. Oral Surg Oral Med Oral Pathol, 1965, 19: 373-382.
[7] Kaugars GE. Internal enamel pearls: report of case[J]. J Am Dent Assoc, 1983, 107(6): 941-943.
[8] Akgül N, Caglayan F, Durna N, et al. Evaluation of enamel pearls by cone-beam computed tomography (CBCT)[J]. Med Oral Patol Oral Cir Bucal, 2012, 17(2): e218-e222.
[9] Hou GL, Tsai CC. Cervical enamel projection and intermediate bifurcational ridge correlated with molar furcation involvements[J]. J Periodontol, 1997, 68(7): 687-693.
[10] Risnes S, Segura JJ, Casado A, et al. Enamel pearls and cervical enamel projections on 2 maxillary molars with localized periodontal disease: case report and histologic study[J]. Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 2000, 89(4): 493-497.
[11] Pedersen PO. The East Greenland Eskimo dentition, numerical variations and anatomy[M]. Copenhagen: Biance Lunos Press, 1949.
[12] Moskow BS, Canut PM. Studies on root enamel (2). Enamel pearls. A review of their morphology, loca-lization, nomenclature, occurrence, classification, his-togenesis and incidence[J]. J Clin Periodontol, 1990, 17(5): 275-281.
[13] Darwazeh A, Hamasha AA. Radiographic evidence of enamel pearls in jordanian dental patients[J]. Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 2000, 89(2): 255-258.
[14] Loh HS. A local study on enamel pearls[J]. Singapore Dent J, 1980, 5(1): 55-59.
[15] Gašperšič D. Histogenetic aspects of the composition and structure of human ectopic enamel, studied by scanning electron microscopy[J]. Arch Oral Biol, 1992, 37(8): 603-611.
[16] Kaminagakura E, Salmon CR, Fonseca DC, et al. Prevalence and microscopic features of enamel pearls from permanent human molars[J]. Braz J Oral Sci, 2011, 10(4): 268-271.
[17] Anderson P, Elliott JC, Bose U, et al. A comparison of the mineral content of enamel and dentine in human premolars and enamel pearls measured by X-ray microtomography[J]. Arch Oral Biol, 1996, 41(3): 281-290.
[18] Gašperšič D. Enamel microhardness and histological features of composite enamel pearls of different size[J]. J Oral Pathol Med, 1995, 24(4): 153-158.
[19] Kim HJ, Kim SY. Cervical enamel projections from a periodontal perspective: a scoping review[J]. Clin Anat, 2024, 37(3): 353-365.
[20] Marshall G, Verdelis K, Peters OA. Morphology of pulpal mineralizations: a scoping review[J]. J Dent, 2023, 139: 104745.
[21] Swan RH, Hurt WC. Cervical enamel projections as an etiologic factor in furcation involvement[J]. J Am Dent Assoc, 1976, 93(2): 342-345.
[22] Ko MJ, Cho CM, Jeong SN. Characteristics of the molar surface after removal of cervical enamel projections: comparison of three different rotating instruments[J]. J Periodontal Implant Sci, 2016, 46(2): 107-115.
[23] Bissada NF, Abdelmalek RG. Incidence of cervical enamel projections and its relationship to furcation involvement in Egyptian skulls[J]. J Periodontol, 1973, 44(9): 583-585.
[24] Blanchard SB, Derderian GM, Averitt TR, et al. Cervical enamel projections and associated pouch-like opening in mandibular furcations[J]. J Periodontol, 2012, 83(2): 198-203.
[25] Kalnins V. Origin of enamel drops and cementicles in the teeth of rodents[J]. J Dent Res, 1952, 31(4): 582-590.
[26] Bower RC. Furcation development of human mandibular first molar teeth. A histologic graphic reconstructional study[J]. J Periodontal Res, 1983, 18(4): 412-419.
[27] Shroff NP, Xu P, Kim S, et al. Proliferation-driven mechanical compression induces signalling centre formation during mammalian organ development[J]. Nat Cell Biol, 2024, 26(4): 519-529.
[28] Kim EJ, Kim HY, Li L, et al. Cuspal shape alterations by bmp4 directing cell proliferation and apoptosis[J]. J Dent Res, 2023, 102(7): 825-834.
[29] Germen M, Baser U, Lacin CC, et al. Periodontitis prevalence, severity, and risk factors: a comparison of the AAP/CDC case definition and the EFP/AAP classification[J]. Int J Environ Res Public Health, 2021, 18(7): 3459.
[30] Emery DC, Cerajewska TL, Seong J, et al. Comparison of blood bacterial communities in periodontal health and periodontal disease[J]. Front Cell Infect Microbiol, 2021, 10: 577485.
[31] Aleksijević LH, Aleksijević M, Škrlec I, et al. Porphyromonas gingivalis virulence factors and clinical significance in periodontal disease and coronary artery diseases[J]. Pathogens, 2022, 11(10): 1173.
[32] Wang BY, Cao A, Ho MH, et al. Identification of microbiological factors associated with pe-riodontal health disparities[J]. Front Cell Infect Microbiol, 2023, 13: 1137067.
[33] Shahoumi LA, Saleh MHA, Meghil MM. Virulence factors of the periodontal pathogens: tools to evade the host immune response and promote carcinogenesis[J]. Microorganisms, 2023, 11(1): 115.
[34] Matthews DC, Tabesh M. Detection of localized tooth-related factors that predispose to periodontal infections[J]. Periodontol 2000, 2004, 34: 136-150.
[35] Atkinson SR. Changing dynamics of the growing face[J]. Am J Orthod, 1949, 35(11): 815-836.
[36] Masters DH, Hoskins Jr SW. Projection of cervical enamel into molar furcations[J]. J Periodontol, 1964, 35(1): 49-53.
[37] Hou GL, Tsai CC. Relationship between periodontal furcation involvement and molar cervical enamel projections[J]. J Periodontol, 1987, 58(10): 715-721.
[38] Machtei EE, Wasenstein SM, Peretz B, et al. The relationship between cervical enamel projection and class Ⅱ furcation defects in humans[J]. Quintessence Int, 1997, 28(5): 315-320.
[39] Chan HL, Oh TJ, Bashutski J, et al. Cervical enamel projections in unusual locations: a case report and mini-review[J]. J Periodontol, 2010, 81(5): 789-795.
[40] Goldstein AR. Enamel pearls as contributing factor in periodontal breakdown[J]. J Am Dent Assoc, 1979, 99(2): 210-211.
[41] Kvaratsthelia S. Prevalence of dentition, dental ar-ches and dental anomalies[J]. Georgian Med News, 2024(347): 177-180.
[42] Hou L, Acharya K, Ghimire B, et al. Clinical and imaging analysis of 22 cases of supernumerary teeth in the mandibular region[J]. J Stomatol Oral Maxillofac Surg, 2024, 125(4S): 101525.
[43] AlHadidi A, Lam PPY, Hassona Y. Developmental and acquired abnormalities of the teeth[J]. Dent Clin North Am, 2024, 68(2): 227-245.
[44] Lisman D, Drath J, Zielińska G, et al. The evidential value of dental calculus in the identification process[J]. Sci Rep, 2023, 13(1): 21666.
[45] Li Q, Luo K, Su Z, et al. Dental calculus: a repository of bioinformation indicating diseases and human evolution[J]. Front Cell Infect Microbiol, 2022, 12: 1035324.
[46] Kao MC, Lin CL, Kung CY, et al. Miniature endoscopic optical coherence tomography for calculus detection[J]. Appl Opt, 2015, 54(24): 7419-7423.
[47] Hsiao TY, Ho YC, Chen MR, et al. Disease activation maps for subgingival dental calculus identification based on intelligent dental optical coherence tomography[J]. Transl Biophotonics, 2021, 3: e202100-001.
[48] Ishikawa M, Kanzaki H, Kodera R, et al. Early diagnosis of aortic calcification through dental X-ray examination for dental pulp stones[J]. Sci Rep, 2023, 13(1): 18576.
[49] Zahran SS, Alamoudi RA. Radiographic evaluation of teeth with pulp stones and pulp canal obliteration: characteristics, and associations with dental parameters[J]. Libyan J Med, 2024, 19(1): 2306768.
[50] Jolivet G, Huck O, Petit C. Evaluation of furcation involvement with diagnostic imaging methods: a systematic review[J]. Dentomaxillofac Radiol, 2022, 51(8): 20210529.
[51] 邢攀峰, 孙俊毅. CBCT在根分叉病变诊疗中的准确性和实用性—文献系统性回顾: 2020年中华口腔医学会口腔颌面放射专业委员会第十八次全国口腔颌面医学影像学专题研讨会论文汇编[C]. 北京: 中华口腔医学会, 2020.
Xing PF, Sun JY. Accuracy and practicality of CBCT in the diagnosis and treatment of root bifurcation lesions—a systematic review of literature: Compilation of Papers from the 18th National Symposium on Oral and Maxillofacial Medical Imaging organized by the Oral and Maxillofacial Radiology Professional Committee of the Chinese Stomatological Association in 2020[C]. Beijing: Chinese Stomatological Association, 2020.
[52] Tsao YP, Neiva R, Al-Shammari K, et al. Factors influencing treatment outcomes in mandibular Class Ⅱ furcation defects[J]. J Periodontol, 2006, 77(4): 641-646.
[53] Mukherjee M, Nair V, Phull T, et al. Biometric analysis of furcation area of molar teeth and its relationship with instrumentation[J]. BMC Oral Health, 2024, 24(1): 436.
[54] Roussa E. Anatomic characteristics of the furcation and root surfaces of molar teeth and their significance in the clinical management of marginal pe-riodontitis[J]. Clin Anat, 1998, 11(3): 177-186.
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