Autotransplantation of teeth as an alternative to dental implantation

Abstract

Autotransplantation of teeth is a considerable option for tooth replacement in adults who are to undergo orthodontic treatment. Being compared with dental implantation, this procedure is more preferable as a grafted tooth functions as a normal one. In this case report, we describe successful autotransplantation of the third molar with complete root formation. To provide better adaptation of the donor tooth, we used its preoperatively printed replica. The donor tooth was immediately placed to the recipient site and splinted for 28 days. Endodontic treatment was initiated 2 weeks after transplantation. Clinical and radiographic findings at 6 and 12 months of follow-up are compared with the results described in the literature.

Background

Nowadays, autotransplantation of teeth is a considerable option for tooth replacement. However, it has not been popular until recently since the rate of surgical complications (eg, inflammatory root resorption and ankylosis) was significantly higher due to the lack of existing knowledge.¹ The prognostic factors of the procedure were analysed in a series of studies.^1–10 Despite some minor distinctions, different researchers share the opinion that the maintenance of periodontal ligament (PDL) cells is of crucial importance.

In 1982, Lindskog and Blomlöf scrutinised the process of periodontal healing. They discovered that PDL is sensitive to changes in osmotic potential and acidity. They also found that fibroblasts die under prolonged exposure to an extraoral environment.¹¹ As a result, inflammatory, replacement or cervical root resorption may occur; in such case a tooth may be lost.^{1 7}

Recipient site preparation requires a considerable amount of time, with a donor tooth being kept extraorally. To decrease this time significantly (up to 30 s), the use of three-dimensional printed replicas was suggested.¹² They also simplified the procedure, so interest in this treatment was revived.

Here, we describe the case of tooth autotransplantation using its stereolithographic replica.

Case presentation

A 34-year-old woman presented to the clinic with mild tenderness in tooth 4.6 when chewing. The previous dental history indicated that a root canal therapy of tooth 4.6 had been performed 2 years earlier. There were neither relevant medical problems nor allergies. The family history was unremarkable.

Investigations

On examination, we found that the crown of tooth 4.6 was fractured (figure 1). Periodontal probing revealed the pocket of 6 mm in depth on the mesial side of the tooth. No pain was detected on percussion, and the mobility of the tooth was normal.

Figure 1.

Preoperative photograph showing crown fracture of tooth 4.6.

Cone beam CT (CBCT) demonstrated localised vertical bone loss. The root canals seemed to be partially obturated (figure 2). Nevertheless, no periapical radiolucency was evident. Based on these findings, we diagnosed vertical root fracture.

Figure 2.

Cone beam CT scan showing marginal bone resorption.

Treatment

We considered several treatment options including dental implantation, prosthetics and orthodontic space closure. As the patient was planning orthodontic treatment and the third molars were to be extracted, the patient was proposed for autotransplantation of a wisdom tooth to the edentulous area.

To determine the adaptability of the donor tooth to the recipient site, we carefully measured the dimensions of the recipient site and potential donor teeth using CBCT images. We selected tooth 3.8 due to its simple root anatomy and correct arch position (figure 3). The CBCT data were exported as a Digital Imaging and Communications in Medicine file and converted into a Standard Triangulation Language file. The replica was printed with the use of acrylic resin and sterilised in autoclave (for 15 min at 121°C).

Figure 3.

Measurements of the donor tooth and the recipient site.

The patient was prescribed with amoxicillin/clavulanic acid 875 mg/125 mg 1 hour prior to surgery. Under local anaesthesia with 4% articaine hydrochloride plus 1:100 000 epinephrine, tooth 4.6 was separated and its fragments were gently extracted with dental elevator. Granulation tissue was removed and the socket was prepared with a carbide bur in accordance with the shape of the donor tooth replica (figure 4). Abundant rinsing with 0.05% chlorhexidine gluconate and sterile saline was performed to eliminate debris. Tooth 3.8 was gently extracted with periotomes and dental elevators and meticulously examined (figure 5). The absence of fractures having been ensured, the tooth was immediately placed into the recipient site and splinted with two fibre posts and flowable resin as there were some concerns about tooth stability (figure 6). Polypropylene 6-0 sutures were used for better soft tissues adaptation (figure 7). The occlusal adjustment of the donor tooth was performed to remove any interferences. The surgical time was 45 min, with the time from extraction of the donor tooth until its placement to the recipient site being less than 1 min.

Figure 4.

Preparation of the recipient site in accordance with the donor tooth replica.

Figure 5.

Extraction of the donor tooth.

Figure 6.

The donor tooth is splinted with two fibre posts and flowable resin.

Figure 7.

Soft tissue adaptation.

After surgery, the patient was prescribed with amoxicillin/clavulanic acid 875 mg/125 mg two times per day for 5 days and nimesulide 100 mg when necessary. Patient was instructed to rinse with 0.2% chlorhexidine gluconate two times per day for a week.

We initiated endodontic treatment 14 days after transplantation. Root canals were medicated with a calcium hydroxide paste and filled with gutta percha, 2 and 4 weeks after surgery, respectively (figure 8). The splint was also removed 4 weeks postoperatively. The overlay ceramic restoration was cemented 12 months later (figure 9).

Figure 8.

Radiograph showing endodontic treatment of the donor tooth.

Figure 9.

One-year follow-up photograph of the tooth after restoration.

Outcome and follow-up

Patient was recalled at 2 weeks, 1, 3, 6 and 12 months following surgery. The mobility of the tooth and the soft tissue contour were assessed. Radiographs were taken immediately after surgery and 6 and 12 months postoperatively. Immediate postsurgical radiographs showed the tooth within the socket with periodontal space of around 1 mm.

After 14 days, the patient presented with no pain or tenderness, with soft tissue healing being satisfactory.

At 1 month postoperatively, no soft tissue inflammation was evident. The splint was removed and the mobility of the tooth was grade 2.

Three months after surgery, the mobility of tooth normalised to grade 1. Six months after surgery, bone tissue was assessed with radiographs. No bone resorption was observed, and periodontal space was clearly seen. On examination, the tooth showed grade 1 mobility.

After 1 year, the tooth remained asymptomatic, the mobility was within normal limits, tenderness to percussion was negative and no probing depths of more than 3 mm were present around the tooth (figure 9). The periapical radiograph showed no inflammation, bone resorption or disappearance of periodontal space (figure 10).

Figure 10.

One-year follow-up radiograph.

Discussion

Teeth are often lost because of complications of caries. The mostly affected teeth are the first permanent molars since they erupt early and have complex anatomy of the occlusal surface.¹³ Being the first key to normal occlusion, they should be restored as soon as possible.¹⁴

At the moment, there are many options for tooth replacement, with autotransplantation being among them. If it is performed properly, a grafted tooth functions as a normal one.⁸ It is particularly important in orthodontic patients since grafted teeth can be moved orthodontically.

The surgery should meet the following requirements: the recipient site should be prepared in accordance with the donor tooth shape; the time of the recipient site preparation should be minimised and the number of fitting attempts with the use of the donor tooth should be as little as possible; the donor tooth should be gently extracted.⁹

Many researchers report that PDL preservation is mandatory for successful autotransplantation of teeth.^{6 15 16} Andreasen showed that fibroblasts are more likely to die in case of prolonged extraoral exposure. They determined that inflammatory root resorption and ankylosis may occur if dry time exceeds 30 and 60 min, respectively.⁶ Leite and Okamoto obtained the similar results.¹⁷ Therefore, when performing surgery, we tried to minimise this time as much as possible.

Park et al reported that careful and atraumatic donor tooth extraction is of crucial importance in terms of PDL preservation. An intraoperative injury to a donor tooth is minimal if it has a single root with simple anatomy.⁹ Sugai et al also showed that autotransplantation of single-rooted molars is more predictable than that of multirooted teeth.⁸ According to these data, we have selected tooth 3.8 for transplantation.

Good adaptation of the recipient site to the donor tooth plays an important role in terms of the overall success. This process can be simplified and fastened with the use of its prototype, not a donor tooth itself. Nowadays, it is possible to take a CBCT scan before surgery and to obtain the necessary data on the donor tooth to design and manufacture its replica.¹⁸ Tooth-like surgical templates are accurate to within 0.25 mm, which is satisfactory in the majority of cases.^{10 19} CBCT imaging also makes diagnosis and planning more simple and surgery more predictable and controllable.²⁰

In some studies, it was hypothesised that using a donor tooth replica to shape the recipient site prior to tooth extraction can dramatically decrease the iatrogenic damage of a donor tooth PDL and increase the success rate of the surgery.^{12 19 21} Nevertheless, Verweij et al found no significant difference between autotransplantation with and without tooth-like templates.¹⁰ However, in practice, tooth replicas can help simplify the procedure and shorten the surgical time.

Different types of surgical guide sterilisations were suggested, with chemical, steam heat and gas plasma sterilisation being among them.²² The effect of sterilisation on the accuracy of the template is still discussed; however, some papers showed no significant dimension changes of templates after steam heat and gas plasma sterilisation.^{22 23} Therefore, we decided to use steam-heat sterilisation in accordance with the instructions of the manufacturer.

The effect of the fixation type on the periodontal healing remains controversial.² Mendes and Rocha stated that splints may affect oral hygiene and lead to some complications, for example, inflammatory root resorption or ankylosis. Therefore, long-term results of the procedure may be compromised.²⁴ Armstrong et al summarised different stabilisation techniques, with short-term flexible splinting being more favourable. It was proposed to stabilise the donor tooth with sutures or even not to use any type of stabilisation, with the success rates of all these procedures being high (over 81.4%).⁵ However, more rigid splinting is also possible if the donor tooth shows low stability.^{4 7}

In previous studies, only teeth with incomplete root formation were preferred for transplantation.⁴ This conception was determined by a possibility of pulp vitality preservation through the process of revascularisation.²⁵ But choosing only such teeth significantly limits the indications for autotransplantation since in most adults root formation in the third molars has already been completed. Therefore, it was suggested to transplant mature teeth and perform endodontic treatment afterwards.³ Nevertheless, Murtadha and Kwok observed the potential for revascularisation of pulp in teeth with complete root formation, so root canal treatment can be omitted in some cases.²⁶ However, we decided to administer a conventional treatment to decrease a risk of postoperative complications.

Patient’s perspective.

That day was just like any other day. I was eating my lunch when suddenly I heard a crack and felt some resistance in my tooth. Biting and chewing abruptly became uncomfortable and I was really scared. I was conscious that a part of my lower molar was absent. I rushed to the dentist to crown the tooth. Unfortunately, I did not realise the seriousness of my problem, so I was shocked when I was told that the tooth was not restorable and the only option would be an extraction.

You would think I could just get rid of the tooth, then place an implant and get over the situation. The thing is, I was thinking about orthodontic treatment and my orthodontist warned me that dental implants might hamper treatment or even make it impossible. Dental implants were, in fact, almost unthinkable for me and I did not really know what to do. It was pretty tough on me.

However, current therapeutic interventions allowed me to forget about my problem. The team of dentists informed me about the possibility of tooth transplantation so I signed a patient informed consent and started treatment. The procedure was absolutely painless and not too long, but I experienced pain after surgery for several days so I had to take my painkillers. Finally, the pain disappeared and the tooth has not disturbed me since that time. To tell the truth, a year has already passed and I have not started orthodontic treatment yet. But, thanks to the novel treatment, I have an opportunity to start it whenever I want.

Learning points.

• Autotransplantation is a good option for tooth replacement especially for patients who need orthodontic treatment.

• When performed correctly, autotransplantation of teeth with complete root formation yields predictable results.

• A stereolithographic tooth replica enables a clinician to minimise extra-oral time needed for the recipient site preparation and simplify the surgery.

• Splinting technique should be carefully selected as it plays an important role in terms of the overall success of the procedure.