A Case Series of Tooth Autotransplantation in Three Children with Different Presenting Complaints

Case 1

A fit and well 7-year-old girl was referred by her GDP having avulsed her upper right central incisor two weeks previously. The tooth was not found at the time of injury, therefore it was not re-implanted.

Examination revealed the patient to be in the mixed dentition with missing UR1 and a supplemental lateral incisor erupting distal to the UL2 (Figure 1).

Sensibility testing of the remaining upper incisors was undertaken and all teeth responded positively to ethyl chloride and electric pulp testing. The UR1 space measured 8 mm in width and the supplemental lateral incisor measured 6 mm mesio-distally. A cone beam CT scan to evaluate the morphology of both the lateral incisors in the upper left anterior region and the available bone in the UR1 region further showed:

For the purposes of space maintenance and aesthetics, an upper removable appliance was designed to replace the UR1. The patient was highly anxious and only managed a sectional impression, thus an acrylic-only denture was constructed and fitted (Figure 2).

The upper left supplemental incisor tooth was planned for autotransplantation into the UR1 socket under general anaesthetic (GA). Further eruption of the upper lateral incisors was encouraged to minimize potential surgical trauma during autotransplantation. The most distal upper left lateral incisor was extracted atraumatically (taking care not to damage the root surface) and transplanted under GA into the UR1 site following socket preparation using couplands elevator and chisel. Figure 3 shows the donor tooth after transplantation.

The gingival margin was sutured to stabilize the autotransplanted tooth and a flexible wire and composite splint was bonded to the transplanted tooth and one tooth either side. The patient was reviewed two weeks later and a periapical radiograph was taken as a post-operative baseline of the stage of root development of the tooth and to confirm a satisfactory position post-operatively (Figure 4).

The splint was removed at four weeks post-surgery and, at that visit, all teeth were responding positively to sensibility testing (Figure 5).

The patient was seen at regular intervals for review and sensibility testing. A periapical radiograph taken one year post-operatively shows continued root development and pulp canal sclerosis of the transplanted tooth, demonstrating that it remained vital (Figure 6).

A sectional fixed appliance was placed on the upper anterior teeth (URC to ULC) for ten weeks to correct the midline shift and to create space for a composite build-up of the transplanted lateral incisor to resemble a central incisor.

The patient is now 10 years old and in the full permanent dentition (Figure 7). Her transplanted tooth remains vital. The patient is aware that a short course of fixed appliances and revision of the composite restoration UR1 in the near future could improve the aesthetics further.

Case 2

An 8-year-old male presented to the department complaining of the appearance of a ‘large front tooth’. Examination revealed a double tooth in the upper right permanent central incisor region. An orthopantomogram (OPT) and periapical radiographs were taken to investigate root morphology and general dental development (Figures 8 and 9). The upper right central incisor was noted to have a fused root canal system with an immature apex. This was confirmed by a CBCT scan (Figure 10). An incidental finding was the presence of an unerupted supplemental upper left lateral incisor which also had an immature apex. Following multidisciplinary input from paediatric dentistry and orthodontics, the following treatment options were discussed with the patient and his parents:

Option 3 was chosen. The UL2 supplemental was at an ideal stage of root development for autotransplantation, however, it was unerupted and would therefore require surgical removal.

The UR1 socket was significantly larger than the root of the donor tooth, therefore sutures were placed to promote a secure and aesthetic gingival architecture. A flexible wire and composite splint was placed which was removed 12 days later. Sensibility tests showed that all upper anteriors were responding positively. Figure 11 shows a periapical radiograph of the transplanted tooth taken before the splint was removed that day. There was also an upper removable appliance (URA) made to reduce the overbite and lessen occlusal forces on the transplanted tooth.

Figure 12 shows the clinical presentation after splint removal. It is evident that there is periodontal pocketing mesially (measuring 3 mm) due to the discrepancy between tooth and socket size.

The transplanted supplemental tooth continued to give a positive response to sensibility testing and demonstrated continued root development (both apically and within the canal) radiographically at 5 months (Figure 13a) and 13 months (Figure 13b) post-operatively. There also appears to be some periodontal healing mesially. A sectional fixed appliance was bonded five months post-operatively to align the anterior teeth (Figure 14). Figure 15 shows the result post-debond.

The long-term plan for this patient is continued monitoring of the transplanted tooth along with further orthodontic alignment when the patient is in the permanent dentition.

Case 3

A 12-year-old female patient was referred to the department with a lower right permanent canine erupting labially to her LR1.

The following treatment options were discussed with the patient:

After a joint discussion with paediatric consultant, consultant orthodontist, patient and parent, option 5 was chosen.

A CBCT scan was taken to assess the donor tooth and recipient site (Figure 16). The findings from this were that the LR3 had a mildly dilacerated apex and that the crown was labially placed. It had not caused resorption of any of the surrounding teeth and there was no evidence of periapical infection associated with the retained LRC. It was evident from an OPT that the roots of the LR4 and LR2 had tipped mesially and distally respectively, due to the absence of a permanent tooth under the LRC. A course of fixed orthodontics was undertaken to upright these teeth to create sufficient space for the LR3.

Figure 17 shows the patient after this initial course of orthodontics. The archwire had been sectioned to clear the surgical site. Under general anaesthetic, the LRC was extracted, the socket was prepared and the LR3 was transplanted into the socket atraumatically. A flexible splint was placed and removed after 4 weeks. A bracket was then bonded to the LR3 and it was incorporated into the fixed appliance with a light nickel titanium (NiTi) wire (Figure 18).

Root canal treatment was commenced on the same day as splint removal (due to the tooth having a mature apex) and the tooth was dressed with non-setting calcium hydroxide. Orthodontic movement of the tooth was completed successfully (Figures 19 and 20).

Discussion

Autotransplantation of teeth is a recognized treatment option in children with suitable clinical presentations. The main advantage is that it avoids the need for a prosthetic tooth replacement and uses autologous tissue, in the form of a tooth from the patient's own dentition, to preserve the periodontal ligament and facilitate favourable aesthetic outcomes.⁴

Implants are contra-indicated in children as the implant will not erupt alongside adjacent teeth as the child grows.⁵

The literature demonstrates varying surgical success rates of autotransplantation, from 79% to 100%^6,7 and, thanks to a selection of studies and case series, the authors were able to identify factors which can improve the outcome for patients.

Autotransplantation ensures maintenance of the alveolar bone level by physiological stimulation of the periodontal ligament. Damage to the periodontal structures and root surfaces may induce ankylosis and external root resorption, which can lead to unfavourable results.⁸ Care must thus be taken to ensure the atraumatic extraction of the donor tooth and to minimize the extra-oral dry time.⁵ Another factor determining the success of the technique is the size of the recipient socket, which should be larger than the donor tooth to ensure minimal trauma to the periodontal ligament and root surface.⁴ For this reason, it is often necessary to carry out augmentation of the socket. This was not necessary in Case 2 due to the extracted double tooth being significantly larger than the donor supplemental tooth, but it was necessary in Cases 1 and 3. In some cases, autotransplantations to existing sockets have been reported to have higher success and survival rates compared with transplantations to augmented sockets.^9,10

Recent developments in three dimensional imaging and printing allow more detailed surgical planning, including the construction of a surgical template of the donor tooth to contour the recipient surgical site, thus minimizing damage to the donor tooth itself.^5,7

In the first two cases, root canal treatment of the donor tooth was not necessary after autotransplantation because the teeth showed evidence of continued vitality and root development. It is widely accepted that to achieve revascularization of the pulp and successful periodontal healing in transplanted teeth, the ideal root development should be three quarters of the full root length.¹¹ Success rates for the autotransplantation of developing premolars are reported to be over 80% when donor tooth root formation was between two-thirds and four-fifths of the total root length.^{3,9,12,13,14,15,16,17,18} Root canal treatment is necessary in fully developed teeth to halt the development of infection-related root resorption.¹¹

Each of the three cases had different splinting times after the procedure based on the donor tooth's response to the surgery. There is no clear consensus about the method or time of splinting donor teeth after autotransplantation, however, rigid fixation over a long period of time is unnecessary and may increase the risk of dento-alveolar ankylosis.^{19,20,21,22,23}

All three cases involved a course of fixed orthodontic therapy. No root resorption was noted in these cases, despite it being a known risk of applying orthodontic forces to teeth. The influence of orthodontic movement on transplanted teeth in the literature is variable.¹⁸ Some studies state that the application of orthodontic forces did not affect root development² or influence the long-term prognosis,¹⁹ whereas others report slight surface resorption and shortening of the root in teeth that had undergone orthodontic rotation.²⁰ This, however, was reported to be of little clinical relevance.

Despite autotransplantation being a well-recognized technique, the amount of robust evidence in this specialist area of surgery is limited, with no randomized controlled trials reported in the literature. There is also a lack of studies with long-term follow-up of patients, with the average follow-up time in the literature being 5–6 years.^7,18,24,25

Conclusion

These clinical cases demonstrate that autotransplantation is a viable treatment option for a socket following avulsion, teeth with an unusual morphology or poor long-term prognosis and ectopic teeth. It details the stages involved in the treatment and planning of autotransplantation in suitable cases with appropriate donor teeth. Further follow-up is required in these cases to determine long-term success.