Tooth Germ Autotransplantation With 24 Months of Follow-up: A Case Report

Dental autotransplantation is an accepted treatment option for the replacement of missing or compromised teeth. It involves the transference of a donor tooth from its original position to a recipient site within the same patient.¹ A primary goal of this procedure is the maintenance of vitality of periodontal ligament cells in the donor tooth to avoid ankylosis.¹ Another pivotal objective, though rarely reached by the clinician, is the maintenance of pulp vitality in the autotransplanted tooth. The stage of root development of the donor tooth is the key factor for successful pulp revascularization. Autotransplantation of a tooth germ with incomplete root formation and an open apex has been reported to offer a greater likelihood of pulp revascularization, thus avoiding the need for additional endodontic treatment.^2,3 Performing the surgical treatment when the patient is at an early age positively impacts the prognosis.⁴ Obtaining revascularization in an autotransplanted tooth germ affords its roots the opportunity to develop and reach complete root formation.²

The following case report describes the autotransplantation of a tooth germ to replace a compromised mandibular first molar in a young patient. Periapical radiographs of the case are shown in Figure 1 through Figure 3, while Figure 4 through Figure 8 provide occlusal views of the various stages of the autotransplantation procedure.

One-and-a-half years after receiving an initial autotransplantation of tooth No. 32 to the No. 19 position, an 18-year-old female patient presented to the authors' clinic for treatment of caries on tooth No. 30 (Figure 4). A periapical radiograph confirmed an unfavorable prognosis of this tooth (Figure 1). Tooth No. 31, meanwhile, was missing. A previous orthopantomogram revealed the presence of an unerupted tooth germ at the No. 1 site. The incomplete formation of the root of the tooth germ and its open apex made it an excellent candidate for autotransplantation to the No. 30 site.

The clinical situation and therapeutic options were explained to the patient, and she agreed with the clinician's suggestion to receive a second autotransplantation. Endodontic treatment was considered but was rejected due to mobility and cavity involvement of tooth No. 30. Implant placement also was discussed but was disregarded because of the relatively young age of the patient.

To reduce the intraoral bacteria load, a professional oral hygiene cleaning and scaling session was performed along with antiseptic therapy (0.12% chlorhexidine mouthrinse), starting 1 week and 3 days, respectively, before the surgical procedure. A prophylaxis with 2 grams of amoxicillin plus clavulanic acid was administered 1 hour before the surgery to reduce the risk of postoperative infection.

The surgical procedure was performed with the patient under local anesthesia (mepivacaine 2% and 1:100,000 adrenaline). Tooth No. 30 was atraumatically extracted (Figure 5). Then, a triangular incision on the vestibular side of the maxillary tuber was elevated to expose the tooth germ at site No. 1. After the atraumatic extraction of the tooth germ No. 1 it was transplanted into the recipient site No. 30 while ensuring that the remaining part of the follicle and the developing roots were left untouched so as to prevent damaging the periodontal ligament cells. A slight alveoloplasty was necessary to prepare the recipient socket (No. 30) to fit the donor tooth (No. 1) (Figure 6). To ensure a proper engagement of the donor tooth, a flowable composite was used to temporarily fixate it to the adjacent tooth.

To avoid subjecting the donor tooth to excessive trauma, selective grinding was performed until a condition of minimal subocclusion was achieved. Several stitches were made using a resorbable 4-0 suture to permanently stabilize the donor tooth after autotransplantation (Figure 7). A postoperative periapical control radiograph was taken at the conclusion of the procedure.

The following postoperative therapies were prescribed for the patient: antibiotic therapy with amoxicillin plus clavulanic acid for 6 days at a dosage of 1 gram every 12 hours; rinsing with 0.12% chlorhexidine mouthrinse for 20 days, starting 24 hours after surgery; and local applications of 1% chlorhexidine gel, 2 times a day for 10 days.

In autotransplantation cases, during follow-up, the viability of the transplanted tooth should be assessed by thermal testing. Data obtained for up to 3 months after autotransplantation is not indicative of the long-term prognosis of the transplanted tooth due to the incidence of false-positive and false-negative results that may occur because of the possibility of pulp shock postoperatively.⁵ In the present case, after 3 months of follow-up, the donor tooth exhibited a positive response to thermal testing.

Six months after the procedure, radiographic examination demonstrated that the transplanted tooth had a radicular contour similar to any other tooth, and the periodontal line spacing and bundle bone were well represented (Figure 2). The tooth exhibited no pathological features at both clinical and radiological examinations at 6, 12, 18, and 24 months' follow-up (Figure 3 and Figure 8) and demonstrated physiological mobility (Table 1).

Autotransplantation in young patients, as in the present case, represents a valid and preferable alternative to the insertion of a dental implant for several reasons. Implants may not be an ideal treatment in young patients because of their residual jaw growth. Furthermore, autotransplantation is typically more economically feasible, as this treatment option does not require the use of biomaterials, implants, or prosthetic crowns, which contribute to increasing the cost of the rehabilitation. Another factor that influenced the choice of treatment in this case was the open apex of the transplanted tooth.

Immature teeth are ideal candidates for transplantation because of their root growth potential and their higher probability of maintaining pulp vitality postoperatively.⁶ According to Mendes and Rocha, wisdom teeth with incomplete root development have a pulp healing rate of 96% compared with 15% for grafted teeth with complete root formation.⁷

Because of the presence of an open apex in an immature tooth, the regeneration capacity of the pulpal vascular tissue preserves the vital tooth after the self-transplantation.⁸ The diameter of the apical foramen is a faithful predictor of pulpal revascularization. Indeed, donor teeth with an apical diameter greater than 1 mm have a reduced risk of necrosis because postoperative revascularization is more likely to be successful.⁹ On the contrary, in teeth with closed apices, pulp revascularization occurs less frequently, with endodontic treatment being required.¹⁰

Preservation and maintenance of the vitality of periodontal ligament cells in the donor tooth are the keys to a successful clinical outcome.^11,12 A study and retrospective survey of dental autotransplantations emphasize the importance of an atraumatic surgical procedure to ensure minimal trauma to the root surface and prevent ankylosis.^13,14 Indeed, natural reorganization of the periodontal fibers occurs when their vitality is preserved.¹² The careful and precise extraction of the donor tooth, therefore, is highly critical for the preservation of the periodontal ligament.¹⁵

Periodontal healing is usually completed after 8 weeks post-treatment and appears radiographically as a continuous space around the root, with an absence of root resorption and the presence of lamina dura.⁹

In the present case, after 24 months of follow-up, two key determinants of a successful autotransplantation were noted: the preservation of pulp vitality and the absence of ankylosis. The success of the autotransplantation performed in this patient may be attributed to the carefully performed surgical procedure, which was executed in an atraumatic fashion to preserve the periodontal ligament of the transplanted tooth, and the incomplete stage of root development of the donor tooth, which helped enable its complete revascularization.

Luigi Tagliatesta, DDS
Specialist in Oral Surgery, Unit of Oral Surgery, Department of Health Sciences, Santi Paolo & Carlo Hospital, University of Milan, Milan, Italy

Federico Guerri, DDS
Resident of Oral Surgery, Department of Health Sciences, Santi Paolo & Carlo Hospital, University of Milan, Milan, Italy

Anna Paola Iannone, DDS
Doctor in Dental Surgery, Department of Health Sciences, Santi Paolo & Carlo Hospital, University of Milan, Milan, Italy

Nadim Oliva, DDS
Resident of Oral Surgery, Department of Health Sciences, Santi Paolo & Carlo Hospital, University of Milan, Milan, Italy