Autotransplantation of immature second premolar combined with alveolar ridge splitting: A long‐term (6‐year) follow‐up case report

Abstract

This case report describes a successful autotransplantation procedure for an impacted mandibular left second premolar with incomplete root formation. Despite caries and root resorption, the patient's mandibular left second primary molar was retained. Furthermore, the severe impaction of the mandibular left second premolar ruled out orthodontic realignment. Due to the young age of the patient, dental implantation was not feasible, leading to the selection of autotransplantation as the preferred method for replacing the retained primary molar. To address the insufficient buccolingual width of the recipient site, a combination of piezosurgery‐assisted alveolar ridge splitting and guided bone regeneration techniques was employed in this autotransplantation procedure.

INTRODUCTION

The second mandibular premolar displayed a notable incidence of impaction. Among impacted teeth, a significant proportion (29.3%) were discovered to have a retained primary tooth [1]. To tackle this issue, general recommendations have been proposed, delineating four main courses of action: retention, modified retention, extraction followed by space closure and extraction with prosthetic replacement [2]. When a primary tooth exhibits a poor prognosis due to factors such as root resorption, caries, periodontal or periapical disease or insufficient aesthetics, the most appropriate approach is extraction followed by prosthetic replacement using conventional bridges or implants. Dental implants are generally discouraged for paediatric patients due to their potential negative effects on alveolar bone growth and subsequent compromise in the positioning of implant‐supported crowns, which correlates with the passive eruption of adjacent teeth [3].

Autogenous tooth transplantation, commonly referred to as autotransplantation, entails surgically moving a tooth from one location within the oral cavity to another in the same individual. This method presents several advantages over alternative treatments, such as fixed partial prostheses or dental implants [4]. The successful implementation of autotransplantation can facilitate the restoration of normal periodontal healing and the preservation of proprioceptive function, encompassing the perception of natural chewing motions and biologic responses to external stimuli. Particularly in young patients, this procedure enables the conservation of pulp vitality through revascularization, consequently promoting complete root formation and osseous development, ultimately yielding aesthetically pleasing results [5].

The periodontal ligament of a transplanted tooth has the potential to stimulate bone formation. However, in instances where donor teeth are placed in recipient sites with insufficient buccolingual spacing, resulting in root protrusion through a bone dehiscence, it becomes necessary to apply graft materials over the exposed root to promote new bone growth. When the alveolar ridge width is insufficient for the planned implant diameter, various horizontal ridge augmentation techniques such as onlay bone grafting, guided bone regeneration (GBR) and alveolar ridge splitting are utilised to ensure proper implant positioning [6]. The alveolar ridge splitting technique is acknowledged as a reliable method for horizontally augmenting atrophic alveolar ridges [7]. This case study presents a treatment approach that integrates autotransplantation in cases of incomplete root formation, assisted by piezosurgery for alveolar ridge splitting and guided bone regeneration techniques, yielding remarkable outcomes.

CASE REPORT

In 2017, a healthy 15‐year‐old girl was referred to our department for the extraction of a problematic mandibular left second molar. Clinical examination revealed extensive caries on tooth #75 with Class II tooth mobility (Miller classification), and the mandibular left second premolar (#35) was missing (Figure 1a,b). A panoramic radiographic examination revealed that tooth #35, with incomplete root formation, was impacted below the root of the mandibular left first molar (#36) along with a dentigerous cyst extensively associated with the inferior alveolar nerve (Figure 1c). Cone beam computed tomography (CBCT) examination showed that the immature tooth #35 was impacted beneath the root of tooth #36, accompanied by a cyst penetrating the lingual inferior cortical bone of the mandible (Figure 1d–f). The diagnosis unveiled a retained deciduous tooth #75 (residual crown), impacted tooth #35 and a dentigerous cyst in the left mandible.

FIGURE 1.

(a, b) Intraoral view displaying extensive caries on tooth #75. (c) Preoperative panoramic radiograph showing inverted impaction of #35 with a pericoronal low‐density image. (d–f) Preoperative CBCT three‐dimensional image revealing obstruction of #35, incomplete development of the apical foramen, proximity of the coronal part to the inferior alveolar nerve canal, with the red line indicating the inferior dental nerve.

The treatment options were thoroughly explained to the patient and her parents, who ultimately opted for the extraction of the impacted tooth and primary molar, followed by autogenous tooth transplantation to replace the lost tooth. Informed consent was obtained prior to the surgery. Based on the CBCT data, the recipient socket had sufficient vertical bone width for autogenous tooth transplantation but lacked horizontal width (Figure 2a–d). Horizontal ridge augmentation was planned and performed under local anaesthesia using lidocaine and 1:100000 epinephrine. A lingual sulcular incision was made from tooth #75 to tooth #36, accompanied by a relieving vertical incision (Figure 2e). A minimally invasive dental elevator was employed to delicately extract the donor tooth, with utmost care to preserve the periodontal ligament. Subsequently, the cyst was excised, and tooth #75 was extracted (Figure 2f). A full‐thickness buccal mucoperiosteal flap was raised from tooth #34 to #37 to expose the buccal alveolar bone. A sagittal symmetrical alveolar split osteotomy, approximately 11 mm in length, was then performed to facilitate subsequent splitting of the buccal cortical bone plate (Figure 2g). The osteotomy was conducted using a piezoelectric surgical device, extending the buccal transverse vertical osteotomy through the cancellous bone until reaching the lingual bone plate. This resulted in an increase in the horizontal width of the recipient socket from 8 mm to 11 mm (Figure 2h,i). Dental implant drills with progressively larger diameters were used to prepare the recipient alveolar socket, into which the donor teeth were immediately transplanted (Figure 2j,k). Autogenous bone chips harvested during the osteotomy were combined with concentrated growth factors (CGF) and implanted into the buccal splitting area. Two CGF membranes were then applied to cover the surface of the autogenous bone implants (Figure 2l–n). Finally, the surgical site was sutured, including through the periosteal release incision (Figure 2o). Resin‐bonded fibre‐reinforced composites were utilised to stabilise the grafted teeth directly on the buccal surface of the adjacent teeth and adjust the graft occlusion (Figure 2p). Post‐operative care consisted of broad‐spectrum antibiotic therapy (amoxicillin 750 mg every 8 h) for 7 days and anti‐inflammatory and analgesic therapy with dexketoprofen (25 mg every 8 h) for 5 days.

FIGURE 2.

(a, b) Preoperative sagittal sectional scan indicating that the length and width of the donor tooth root were approximately 10.4 and 7.2 mm, respectively. (c, d) Preoperative cross‐sectional view revealing that the vertical and horizontal widths of the recipient socket were approximately 13.4 and 7.8 mm, respectively. (e) Lingual sulcular incision made from tooth #75 to #37. (f) Extraction of teeth #75 and #35, with preservation of the epithelial root sheath at the apex of #35. (g) Sagittal split of the alveolar bone at the buccal plate of the recipient socket. (h, i) Expansion of the horizontal width from 8 to 11 mm. (j) Recipient socket prepared for dental implant surgery. (k) Accurate placement of the donated tooth into the recipient socket. (l) Mixture of autogenous bone chips and CGF. (m) Preparation of CGF membranes. (n) Application of CGF membranes. (o) Buccal and lingual views after suturing. (p) Stabilization of the transplanted tooth with resin‐bonded fibre‐reinforced composite.

During follow‐up visits (at intervals of 1, 3, 6, 9, 12, 18, 24 and 72 months), clinical assessments revealed no signs or symptoms of spontaneous pain, pain on percussion or palpation‐related discomfort (Figure 3a–p). The transplanted tooth exhibited normal physiological mobility and a periodontal probing depth of less than 3 mm at intervals of 6, 12, 18 and 24 months (Figure 3q–x). Radiographic examinations demonstrated a continuous intact periodontal ligament (PDL), continuous lamina dura and ongoing root development without any signs of inflammation or resorption (Figure 4a–h). Pulp vitality tests were conducted at 6, 12 and 18 months post‐surgery, with results from the pulp electrical vitality test indicating normal pulp vitality of the transplanted teeth (Figure 4i–k). Cross‐sectional CBCT images taken immediately after surgery revealed an increase in ridge width to 12.4 mm, which decreased to 11.1 mm, 12 months post‐surgery (Figure 4l,m).

FIGURE 3.

(a–p) Buccal and occlusal views at 1, 3, 6, 9, 12, 18, 24 and 72 months post‐operation. (q, r) Normal periodontal probing at 6 months post‐surgery. (s, t) Normal periodontal probing at 12 months post‐surgery. (u, v) Normal periodontal probing at 18 months post‐surgery. (w, x) Normal periodontal probing at 24 months post‐surgery.

FIGURE 4.

(a–h) Radiographs taken at 1, 3, 6, 9, 12, 18, 24 and 72 months post‐operatively, demonstrating gradual closure of the apical foramen, good periodontal condition and healing of the ridge split line. (i) Pulp electrical vitality test result at 6 months post‐surgery indicated a value of 37. (j) Pulp electrical vitality test result at 12 months post‐surgery indicated a value of 40. (k) Pulp electrical vitality test result at 18 months post‐surgery indicated a value of 16. (l) Cross‐sectional view taken immediately post‐operation showing a post‐operative crest width increase to 12.4 mm. (m) Cross‐section taken 1 year after surgery revealing a reduction in post‐operative alveolar ridge width to 11.1 mm.

DISCUSSION

In children and adolescents, autografting offers potential benefits such as osteoinduction, restoration of the normal alveolar process and regeneration of periodontal tissue, encompassing the periodontal ligament, nerve and alveolar bone [8]. Research indicates that post‐operative root development and pulp vascular reconstruction do not occur following transplantation of mature teeth. Therefore, if a tooth is planned for transplantation, root canal treatment should be carried out beforehand. Alternatively, if root canal treatment is not completed prior to transplantation, it should commence 1–2 weeks afterwards to mitigate the risk of potential inflammatory root resorption stemming from necrotic pulp [9]. In contrast, autotransplantation of teeth with incomplete root formation offers the advantage of pulp revascularization and reinnervation, thereby eliminating the need for endodontic treatment [10]. Andreasen and colleagues conducted a study determining that autografting is a suitable treatment option for immature teeth ranging from Stage 2 (representing half of the root length) up to Stage 4 (representing three‐quarters to less than four‐quarters of the root length). However, teeth at Stage 5 (indicating complete root formation and semiapical retraction) are not recommended due to the high likelihood of pulpal necrosis development [11]. In this case, the transplanted tooth exhibited normal pulp viability in the last three pulp tests. Favourable healing of the periodontal ligament depends on the preservation of viable cells on the root. Studies have suggested that Hertwig's epithelial root sheath may be an explanatory factor for variations in root growth [12, 13]. The preservation of the epithelial root sheath in this case may significantly contribute to the continued obliteration of the apical foramen in the transplanted tooth.

The recipient site should possess ample bone support with sufficient attached keratinised tissue to facilitate tooth stabilization, free from any signs of inflammation or infection. [14] In this case, we opted to utilise a ridge splitting technique to widen the mandibular alveolar ridge, addressing inadequate bone width at the implant site. Alveolar ridge splitting is a technique for bone expansion used in the treatment of atrophic ridges with horizontal deficits. Clinical experience has shown that the ridge splitting technique can be a useful method for managing a narrow ridge. An average gain of 3.8 mm in thickness of the alveolar ridge can be expected [15]. Guided bone regeneration (GBR) assists in maintaining bone height and width during the alveolar ridge splitting/expansion technique. Despite advancements in bone substitute materials, autogenous bone grafts remain the ‘gold standard’ due to their osteogenic, osteoinductive and osteoconductive properties, as well as their nonimmunogenic nature [16]. CGF has shown efficacy in enhancing cell proliferation, migration and differentiation, as well as in promoting angiogenesis and osteogenesis, thus demonstrating significant potential in the realm of tissue regeneration [17, 18]. In this case, we employed a combination of harvested autogenous bone fragments and CGF during surgery to enhance osteogenesis and facilitate soft tissue healing.

CONCLUSION

Autologous dental grafting serves as a reliable alternative to dental implants, particularly for adolescent patients with insufficient alveolar ridge bone width in the implantation area. Autologous tooth transplantation with incompletely developed tooth roots, along with piezoelectric surgery‐assisted alveolar ridge splitting and guided bone regeneration technology, can maintain dental pulp vitality and promote the completion of root development through revascularization. Additionally, preserving the epithelial root sheath promotes complete tooth root development, resulting in improved functionality and aesthetics.

AUTHOR CONTRIBUTIONS

Conceptualization, Y.W. and L.C.; methodology, Y.W., Y.P., C.F., L.C., Z.S. and J.W.; writing—original draft preparation, Y.P. and C.F.; writing—review and editing, Y.W., L.C., C.F., Z.S. and J.W. All authors have read and agreed to the published version of the manuscript.

FUNDING INFORMATION

This research was supported by Fujian Provincial Department of Finance Special Fund [Grant No. 22SCZZX010; 2023CZZX04], Fujian Provincial Health Technology Project [Grant No. 2020CXB031], Fujian Provincial Department of Science and Technology [Grant No. 2021J01805] and Clinical Research Center for Oral Tissue Deficiency Diseases of Fujian Province, School and Hospital of Stomatology, Fujian Medical University [Grant No. 2024Clin004].

Supporting information

Appendix S1.

Feng C, Pan Y, Chen L, Wang J, Shi Z, Wu Y. Autotransplantation of immature second premolar combined with alveolar ridge splitting: A long‐term (6‐year) follow‐up case report. Aust Endod J. 2024;50:693–699. 10.1111/aej.12886

DATA AVAILABILITY STATEMENT

Patient data for this autotransplantation case report were collected and documented in Appendix S1, in accordance with the guidelines established by Nagendrababu et al. [19]. For further details on patient‐related data collection and reporting, please refer to Appendix S1.