Separate apical root formation of injured immature teeth: a case series and literature review

This report presents three cases of separated root tip formation following traumatic injury with or without inflammation. The first case showed continued separate apical root formation; however, development of the main root with bony ingrowth was absent. The second case showed that separated root formation continued under the 2-year inflammatory conditions, even after apexification. The third patient showed partially connected root tip formation after apexification. By summarizing previously reported similar cases, we assessed the injury type, prevalence age, treatment performed and pattern of root development. This phenomenon may be elucidated by the special features of the apical papilla (AP). Understanding the capability of AP could help with treatments, such as regenerative endodontic procedures and trauma management for immature permanent teeth.

Apical papilla; Hertwig’s epithelial root sheath (HERS); Separated root tip; Trauma; Inflammation

[1] Flores MT, Andersson L, Andreasen JO, Bakland LK, Malmgren B, Barnett F, et al. Guidelines for the management of traumatic dental injuries. II. Avulsion of permanent teeth. Dental Traumatology. 2007; 23: 130–136.

[2] Sonoyama W, Liu Y, Yamaza T, Tuan RS, Wang S, Shi S, et al. Characterization of the apical papilla and its residing stem cells from human immature permanent teeth: a pilot study. Journal of Endodontics. 2008; 34: 166–171.

[3] Kim TH, Bae CH, Lee JC, Ko SO, Yang X, Jiang R, et al. β-catenin is required in odontoblasts for tooth root formation. Journal of Dental Research. 2013; 92: 215–221.

[4] Cate ART. The role of epithelium in the development, structure and function of the tissues of tooth support. Oral Diseases. 1996; 2: 55–62.

[5] Li J, Parada C, Chai Y. Cellular and molecular mechanisms of tooth root development. Development. 2017; 144: 374–384.

[6] Im Y, Kim Y, Kim H, Nam S. Invasion of alveolar bone into root canal after traumatic injury. Journal of the Korean Academy of Pediatric Dentistry. 2011; 38: 399–406.

[7] Driesen RB, Gervois P, Vangansewinkel T, Lambrichts I. Unraveling the role of the apical papilla during dental root maturation. Frontiers in Cell and Developmental Biology. 2021; 9: 665600.

[8] Welbury R, Walton AG. Continued apexogenesis of immature permanent incisors following trauma. British Dental Journal. 1999; 187: 643–644.

[9] Kumar N, Kumari R, Gauba K. An aberrant root development in severely extruded immature young permanent tooth: a case report. Journal of South Asian Association of Pediatric Dentistry. 2020; 3: 84–87.

[10] Jung IY, Kim ES, Lee CY, Lee SJ. Continued development of the root separated from the main root. Journal of Endodontics. 2011; 37: 711–714.

[11] Korolenkova MV, Rakhmanova MS. Phantom root as dental trauma complication in immature teeth (systematic literature and clinical cases review). Stomatologiya. 2021; 100: 53–57. (In Russian)

[12] Andreasen JQ, Ravn JJ. Epidemiology of traumatic dental injuries to primary and permanent teeth in a Danish population sample. International Journal of Oral Surgery. 1972; 1: 235–239.

[13] Lee JE, Kim YJ, Kim HJ, Nam SH. Continued root development after avulsion of immature teeth. Journal of the Korean Academy of Pediatric Dentistry. 2013; 40: 127–132.

[14] Gibson AC. Continued root development after traumatic avulsion of partly-formed permanent incisor. British Dental Journal. 1969; 126: 356–357.

[15] Barker BC, Mayne JR. Some unusual cases of apexification subsequent to trauma. Oral Surgery, Oral Medicine, Oral Pathology, and Oral Radiology. 1975; 39: 144–150.

[16] Arrow P. An unusual healing of a replanted permanent lateral incisor. Australian Dental Journal. 2009; 54: 57–60.

[17] Andreasen JO, Kristerson L, Andreasen FM. Damage of the Hertwig’s epithelial root sheath: effect upon root growth after autotransplantation of teeth in monkeys. Dental Traumatology. 1988; 4: 145–151.

[18] Jiang X, Liu H. An uncommon type of segmental root development after revitalization. International Endodontic Journal. 2020; 53: 1728–1741.

[19] Palma PJ, Martins J, Diogo P, Sequeira D, Ramos JC, Diogenes A, et al. Does apical papilla survive and develop in apical periodontitis presence after regenerative endodontic procedures? Research Journal of Applied Sciences. 2019; 9: 3942.

[20] Wu ZF, Lu LJ, Zheng HY, Tu Y, Shi Y, Zhou ZH, et al. Separated root tip formation associated with a fractured tubercle of dens evaginatus: a case report. World Journal of Clinical Cases. 2021; 9: 2944–2950.

[21] Yang SF, Yang ZP, Chang KW. Continuing root formation following apexification treatment. Dental Traumatology. 1990; 6: 232–235.

[22] Huang GT, Sonoyama W, Liu Y, Liu H, Wang S, Shi S. The hidden treasure in apical papilla: the potential role in pulp/dentin regeneration and bioroot engineering. Journal of Endodontics. 2008; 34: 645–651.

[23] Levitan ME, Himel VT. Dens evaginatus: literature review, pathophysiology, and comprehensive treatment regimen. Journal of Endodontics. 2006; 32: 1–9.

[24] Palma PJ, Ramos JC, Martins JB, Diogenes A, Figueiredo MH, Ferreira P, et al. Histologic evaluation of regenerative endodontic procedures with the use of chitosan scaffolds in immature dog teeth with apical periodontitis. Journal of Endodontics. 2017; 43: 1279–1287.

[25] Tamanna S, Rehman A, Tewari RK, Mishra SK. A segmental root development as an unusual healing response to the revitalization of mandibular second premolar. Journal of Indian Society of Pedodontics and Preventive Dentistry. 2022; 40: 94.

[26] Nair PN. Apical periodontitis: a dynamic encounter between root canal infection and host response. Periodontology 2000. 1997; 13: 121–148.

[27] Smith BE, Thaler MN. Detached root apexogenesis. Oral Surgery, Oral Medicine, Oral Pathology, and Oral Radiology. 1992; 73: 129.

[28] Goel BR, Goel S. Detached root formation following trauma—a case report. Endodontology. 1993; 5: 7–8.

[29] Abirami R, Revathy V, Abharna R. Aberrant root formation—an unreported complication of dental trauma. Journal of Indian Society of Pedodontics and Preventive Dentistry. 2018; 36: 216–219.