Clinical efficacy of early intervention timing for inversely impacted maxillary central incisors

Background: Maxillary Impacted Central Incisors are a common oral issue among children with mixed dentition. This study evaluates the effectiveness of early traction treatment, which is vital for clinical treatment and management. Methods: This study included 59 patients with maxillary impacted central incisors, who were divided into three groups based on Nolla’s method: the early group (Nolla 6–7), middle group (Nolla 8), and late group (Nolla 9–10). Mimics software was used to create 3 Dimensions (3D) reconstructions of postoperative Cone-beam computed tomography (CBCT) scans, which were used to compare the tooth volume and surface area between the impacted and contralateral teeth, as well as sagittal measurements of root length and loss of height on the labial-palatal aspects of the alveolar bone. Doppler laser flowmetry was used to assess pulpal blood flow in impacted and contralateral teeth three months after surgery. Results: Significant differences in root length, tooth volume, and surface area were observed between impacted and contralateral teeth in the middle and late groups (p < 0.05). The early group, however, showed significant differences in the labial-palatal height differential of the alveolar bone between the impacted teeth and their contralateral counterparts compared to the middle and late groups (p < 0.05). The study found no significant differences in pulpal vitality among the three groups (p > 0.05). Conclusions: The study’s results indicate that orthodontic treatment during Nolla stages 6–7 is more beneficial in the development of impacted teeth in patients. This study supports the early orthodontic treatment approach in clinical practice.

Impacted tooth; Early intervention; Three-dimensional reconstruction; Pulp blood flow volume

[1] Seehra J, Yaqoob O, Patel S, O’Neill J, Bryant C, Noar J, et al. National clinical guidelines for the management of unerupted maxillary incisors in children. British Dental Journal. 2018; 224: 779–785.

[2] Tan C. Prevalence, characteristic features, and complications associated with the occurrence of unerupted permanent incisors. PLOS ONE. 2018; 13: e199501.

[3] Lana Mattiello FD, Deon Rizzatto SM, Macedo de Menezes L, Araújo EA, Kim KB, Martinelli de Lima E. Dimensional and morphologic characteristics of unilateral impacted maxillary central incisors. American Journal of Orthodontics and Dentofacial Orthopedics. 2022; 162: 340–347.

[4] Lyu J, Lin Y, Lin H, Zhu P, Xu Y. New clues for early management of maxillary impacted central incisors based on 3-dimensional reconstructed models. American Journal of Orthodontics and Dentofacial Orthopedics. 2018; 154: 390–396.

[5] Hui J, Niu Y, Jin R, Yang X, Wang J, Pan H, et al. An analysis of clinical and imaging features of unilateral impacted maxillary central incisors: a cross-sectional study. American Journal of Orthodontics and Dentofacial Orthopedics. 2022; 161: e96–e104.

[6] Mockute G. The morphology of impacted maxillary central incisors: a systematic review. Medicina. 2022; 58: 462.

[7] Weissheimer T, Silva EJNL, Pinto KP, Só GB, Rosa RA, Só MVR. Do orthodontic tooth movements induce pulp necrosis? A systematic review. International Endodontic Journal. 2021; 54: 1246–1262.

[8] Wang XC. Cone-beam CT analysis on the treatment efficacy in the vertically impacted maxillary central incisors. Chinese Journal of Stomatology. 2019; 54: 739–744. (In Chinese)

[9] Sun H, Hu R, Ren M, Lin Y, Wang X, Sun C, et al. The treatment timing of labial inversely impacted maxillary central incisors: a prospective study. The Angle Orthodontist. 2016; 86: 768–774.

[10] Wu G, He S, Chi J, Sun H, Ye H, Bhikoo C, et al. The differences of root morphology and root length between different types of impacted maxillary central incisors: a retrospective cone-beam computed tomography study. American Journal of Orthodontics and Dentofacial Orthopedics. 2022; 161: 548–556.

[11] Botelho S, Perussolo J, Misawa M, Zadeh H, Araújo M. The basal bone and alveolar process in the maxillary anterior region in humans: a cone beam computed tomographic study. The International Journal of Periodontics & Restorative Dentistry. 2020; 40: 907–914.

[12] Kim Y, Park JU, Kook Y. Alveolar bone loss around incisors in surgical skeletal class III patients. The Angle Orthodontist. 2009; 79: 676–682.

[13] Ma H, Li W, Xu L, Hou J, Wang X, Ding S, et al. Morphometric evaluation of the alveolar bone around central incisors during surgical orthodontic treatment of high-angle skeletal class III malocclusion. Orthodontics & Craniofacial Research. 2021; 24: 87–95.

[14] Wang XM, Ma LZ, Yan MF, Zheng J, Wang M, Hui X. The variation in crown-root morphology of anterior teeth assessed with cone-beam computed tomography. Dental Press Journal of Orthodontics. 2022; 27: e222079.

[15] Yang K, Guo F, Zhou Z, Hui Z, Wang Z, Wang J, et al. Laser doppler flowmetry to detect pulp vitality, clinical reference range and coincidence rate for pulpal blood flow in permanent maxillary incisors in Chinese children: a clinical study. BMC Oral Health. 2023; 23: 283.

[16] Pan W, Yu L, Chen S, Zhou J, Chi J, Voliere G, et al. Morphometric evaluation of alveolar bone after orthodontic treatment of multiple impacted teeth in the unilateral maxillary anterior region. American Journal of Orthodontics and Dentofacial Orthopedics. 2023; 164: 783–792.

[17] Sun H, Wang Y, Sun C, Ye Q, Dai W, Wang X, et al. Root morphology and development of labial inversely impacted maxillary central incisors in the mixed dentition: a retrospective cone-beam computed tomography study. American Journal of Orthodontics and Dentofacial Orthopedics. 2014; 146: 709–716.

[18] Park M, Kim S, Jeon M, Jung U, Lee J, Choi H, et al. Evaluation of the apical complex and the coronal pulp as a stem cell source for dentin-pulp regeneration. Journal of Endodontics. 2020; 46: 224–231.e3.

[19] Xu L, Tang L, Jin F, Liu XH, Yu JH, Wu JJ, et al. The apical region of developing tooth root constitutes a complex and maintains the ability to generate root and periodontium-like tissues. Journal of Periodontal Research. 2009; 44: 275–282.

[20] Wang Y, Chen X, Zhou D, Zheng L, Li X, Peng Y. Appropriate timing of treatment contributes to better root development of impacted anterior teeth in children. American Journal of Orthodontics and Dentofacial Orthopedics. 2024; 165: 18–26.

[21] Cao D, Shao B, Izadikhah I, Xie L, Wu B, Li H, et al. Root dilaceration in maxillary impacted canines and adjacent teeth: a retrospective analysis of the difference between buccal and palatal impaction. American Journal of Orthodontics and Dentofacial Orthopedics. 2021; 159: 167–174.

[22] Ahlbrecht CA. Three-dimensional characterization of root morphology for maxillary incisors. PLOS ONE. 2017; 12: e178728.

[23] Yordanova G. Impacted upper central incisors—frequency and factors complicating the treatment protocol. Folia Medica. 2021; 63: 405–412.

[24] Ozcan G, Sekerci A. Classification of alveolar bone destruction patterns on maxillary molars by using cone-beam computed tomography. Nigerian Journal of Clinical Practice. 2017; 20: 1010.

[25] Becker A, Brin I, Ben-Bassat Y, Zilberman Y, Chaushu S. Closed-eruption surgical technique for impacted maxillary incisors: a postorthodontic periodontal evaluation. American Journal of Orthodontics and Dentofacial Orthopedics. 2002; 122: 9–14.

[26] Calil LR. Periodontal status of maxillary central incisors after orthodontic traction: a longitudinal follow-up. Journal of Applied Oral Science. 2022; 30: e20210492.

[27] Uğur-Aydın Z, Kılınç H, Akbaş Y, Usta SN. Evaluation of the effect of different desensitizers on pulpal blood flow after full crown preparation using laser Doppler flowmetry: a randomized clinical trial. Odontology. 2024; 112: 272–278.

[28] Naoum S, Goonewardene M, Abbott PV, Karunanayake K, Budgeon C. Changes in pulp blood flow and pulp sensibility resulting from surgically assisted rapid maxillary expansion: a clinical study. American Journal of Orthodontics and Dentofacial Orthopedics. 2019; 155: 632–641.

[29] Lima TFR, dos Santos SL, da Silva Fidalgo TK, Silva EJNL. Vitality tests for pulp diagnosis of traumatized teeth: a systematic review. Journal of Endodontics. 2019; 45: 490–499.

[30] Vitali FC, Cardoso IV, Mello FW, Flores-Mir C, Andrada AC, Dutra-Horstmann KL, et al. Association between orthodontic force and dental pulp changes: a systematic review of clinical and radiographic outcomes. Journal of Endodontics. 2022; 48: 298–311.