Autotransplantation of an impacted migrated mandibular canine using platelet-rich fibrin and physio-dispenser system: a report of two cases

A tooth can be surgically relocated within the same patient via a procedure called autotransplantation. It can be described as a controlled replantation of an extracted tooth into a new, surgically prepared socket.¹ It can be interpreted as the meticulous replantation of a retrieved tooth into a fresh socket that has undergone surgery. The preservation and regeneration of the periodontal ligament is essential for the treatment's success. Patients with failing or missing teeth may find autotransplantation to be the best course of treatment when carried out by a multidisciplinary team.

Various reasons could necessitate an autotransplantation procedure, such as teeth with advanced caries, avulsed young permanent teeth and congenitally missing teeth (tooth agenesis).^2,3 Autotransplantation may also be considered as a treatment option for atypical tooth eruption, as in the case of impacted and migrated canines.

Impacted canines can be managed by surgical exposure followed by fixed orthodontic therapy; however, it may not be possible to use that treatment option in cases of a migrated canine. In these situations, an easier and more rapid therapeutic option would be an auto-transfer of the canine into a more favourable position. Hale et al in 1965 were the first to document autogenous tooth transplantation and their methodology is still being practised to date.⁴

Owing to the contraindications for osseo-integrated implants in young patients, autotransplantation plays a significant role in the replacement of lost teeth in these individuals. In contrast to osseo-integrated implants, which are stationary and do not erupt, causing infra-occlusion, the autotransplanted tooth has the ability to preserve the alveolar ridge and adapt functionally, which is crucial and advantageous. ⁵

In the past few decades, a number of biomaterials have been used to fill osseous defects and facilitate wound healing, such as freeze dried bone, tricalcium phosphate and bioactive glass. Recently, however, focus has shifted to the use of an autogenous material, platelet rich fibrin (PRF), which consists of an osteo-inductive biodegradable scaffold comprising platelets, growth factors, cytokines and stem cells.^6,7 This leukocyte platelet-rich fibrin matrix stimulates the patient's own cells towards a healing regenerative response.⁸

PRF is now used in dentistry to repair and regenerate dental and oral tissues. It is collected by a simple blood collection from the patient, followed by immediate centrifugation process. In this report, we used PRF in both cases as an adjunct to the surgical process to enhance soft tissue and bone healing and regeneration.

A physio-dispenser is an electrical device that is traditionally used to prepare the osteotomy site for implant placement. It consists of a motor in the central unit, which provides high torque at varying rpm, a handpiece attachment, foot pedal and a peristaltic pump for irrigation. The advantages of using the physio-dispenser in surgical procedures are that bone can be cut very efficiently with controlled torque and speed. Further, there is a constant saline irrigation system that washes away the bone debris and blood and also acts as a coolant. Hence, we used the physio-dispenser in the surgical procedure, rather than a conventional micromotor drill, to reduce the amount of heat generated during bone removal, thus minimizing post-operative pain and swelling.

Case report

The management of two cases of impacted and migrated mandibular canines with autotransplantation are reported. The procedure involved the use of PRF and a physio-dispenser system to improve the treatment prognosis.

Case 1

A 14-year-old female patient reported to the department with the chief complaint of having forwardly placed upper front teeth. No known medical and family history were reported by the patient. An orthopantomogram and a mandibular occlusal radiograph (Figure 1a,b) showed that the mandibular right canine (LR3) was vertically impacted between the apex of the mandibular right central and lateral incisors. Intra-oral examination revealed a retained lower right primary canine, which showed no mobility (Figure 1c).

Case 2

A 13-year-old female patient reported to the department with the chief complaint of forwardly placed upper front teeth. No known medical and family history were reported by the patient. An orthopantomogram and a mandibular occlusal radiograph (Figure 2a,b) showed that the mandibular right canine (LR3) was horizontally impacted with its apex lying at the apex of mandibular first premolar, crossing the midline, to end at the apex of mandibular left lateral incisor. On intra-oral examination, a retained lower right primary canine was noted, which showed grade III mobility (Figure 2c).

In both the cases, the patient was informed about the condition and, after orthodontic consultation, the possibility of orthodontic extrusion and alignment was ruled out. The decision was made to undertake autotransplantation of the canine. Case 1 required the creation of space near the primary canine (equal to the mesiodistal width of the contralateral canine), thus pre-treatment fixed orthodontic therapy (open coiled spring), which was undertaken for a period of almost 6 months.

In Case 2, there was already an adequate amount of space available for the transplantation procedure.

Treatment process

Informed written consent was given by the patient's parents before the procedure. An inferior alveolar nerve block was given bilaterally, and a full thickness papilla preservation flap was raised up to the level of the mucogingival junction. The overlying bone was surgically removed to uncover the crown of the impacted canine. The tooth was luxated and exarticulated from the impacted socket to assess the dimensions of the tooth and immediately placed back.

The primary canine was extracted and a socket of appropriate dimension was then created manually at the recipient site with a physio-dispenser and suitable implant drills (Figure 3). The dimensions of this socket corresponded to the dimensions of the impacted and migrated canine.

Following the creation of the socket, approximately 5 ml of whole venous blood was collected from each patient in sterile, 6-ml capacity vacutainer tubes without anticoagulant. After being marked, the vacutainer tubes were loaded into a centrifuge and spun at 3000rpm for 10 minutes.⁶ To obtain platelet rich fibrin, the middle fraction, comprising the fibrin clot, was collected 2 mm below the lower dividing line. The PRF was inserted inside the socket, followed by the canine to ensure that the entire root was covered by the PRF scaffold (Figure 3).

In Case 2, the labial cortical plate was compromised during the procedure, exposing the roots of the canine labially after transplantation. An allogenic bone graft was placed between the root and the gingival flap, following which bioresorbable membrane was placed between the bone substitute and the gingival flap. Silk 4/o suture was used to close the soft tissue flap securing the bone graft.

The transplanted canines were relieved from occlusion and were stabilized by a splint for 2 weeks using an archwire in Case 1 and a twisted ligature wire in Case 2.

The patients were recalled after 1 week to assess the healing status of the tooth. Sutures were removed during this visit as healing appeared satisfactory. Intentional root canal therapy was initiated for the canines. Calcium hydroxide intra-canal medicament was placed for a period of 2 weeks, following which the canines were obturated (Figure 4) The non-rigid splints were removed after 2 weeks. Both patients were reviewed at 4 weeks, 8 weeks, 6 months and 1 year. Both patients were asymptomatic during recall visits.

After a 2 year follow up, the clinical examination of the transplanted tooth reported no pathological signs or symptoms, mobility, or inflammation in either of the cases. On radiographic examination, there was a patent periodontal ligament (PDL) space with no signs of ankylosis or inflammation (Figure 4). Bone growth around the transplanted tooth was considered satisfactory.

Discussion

Nodine, and Ando et al noted that impacted and migrated mandibular canines are commonly discovered with no clear signs suggesting their existence.^9,10 In both of the present cases, the canine was asymptomatic and accidentally diagnosed during routine examination.

Autotransplantion is the relocation of a tooth from one site to another within the same individual. A healthy PDL is the most crucial factor determining the success of the procedure. The PDL governs the reattachment and retention of the tooth in the socket. When damage to the PDL is beyond the point of repair, treatment failure may occur owing to inflammatory or replacement resorption.^11,12 We attempted to improve the prognosis of our treatment by adopting measures to improve the healing of the PDL with the use of the physio dispenser system and PRF.

Various studies have shown that drilling through bone generates much heat owing to the friction between the drill and the bone. This heat is absorbed by the surrounding bone and is detrimental to healing because it causes denaturation of enzymatic and membrane proteins, and dehydration and desiccation of the bone. Eriksson and Albrektsson stated that the critical temperature of bone ranges between 44°C and 47°C. ¹³ The use of a physio-dispenser, which is a low-speed, high-torque (850–1250rpm, 20–50 Ncm) drilling system with an internal irrigation system for cooling, was chosen over the conventional micromotor drill to prepare the socket for the transmigrated canine. The advantage of using this system ensured that the temperature of the bone was maintained <33.8°C.

An autologous second-generation platelet concentrate known as PRF was generated by centrifuging freshly drawn patient blood to separate its components, which include fibrin, platelets, growth factors, leukocytes, and stem cells. By stimulating cell differentiation while preserving an anti-inflammatory and infection-free environment, it has proven to be an efficient biomaterial for tissue repair and regeneration.⁷ PRF enhances osteogenesis in the surgical site and serves as an optimized blood clot.¹⁴ The easy collection and low cost of preparation is an added advantage of using PRF.

The rupture of the neurovascular bundle during tooth extraction is expected to impede revascularization for teeth with mature roots, leading to pulp necrosis. Endodontic therapy in this instance ought to be carried out within 15 days of transplantation.¹⁵ Further, as the socket at the recipient site was created manually in both the cases, there was a possibility of incurring an additional injury to the periodontal ligament during the procedure, which did occur in Case 2, where there was a perforation of the labial cortical plate. For these reasons, an elective root canal treatment was carried out 1 week after the transplantation process to curb any source of inflammatory resorption during the healing and re-attachment of periodontal ligament. Calcium hydroxide was used as an intra-canal dressing as part of the endodontic procedure since its high pH and antibacterial qualities aid in preventing root resorption and promote the healing process. ¹⁶

The success of an autotransplant is strongly dependent on patient selection. In order for autotransplantation to be effective, candidates must be in good health, exhibit excellent oral hygiene, and be receptive to routine dental care. Following post-operative instructions and making themselves available for follow-up appointments are also requirements for patients; cooperation and understanding are crucial for predictable outcomes. In this report, both patients fulfilled these criteria, which could have contributed to the successful outcomes.^17,18

The 2-year follow up in both cases confirmed the clinical and radiographic success of the autotransplantation of the migrated canine, making it a viable treatment option particularly for patients with restricted financial resources, or for functional and aesthetic rehabilitation in growing patients when orthodontic space closure is not predictable or practical, and where restorative implant placement is not possible owing to expected future facial growth and dento-alveolar change. The additional use of PRF and the physio-dispenser system in the treatment protocol could improve the prognosis of the procedure, even in cases where the donor tooth is not in the ideal stage of root development.

Conclusion

From this case report, it may be inferred that autogenous transplantation can be taken into account as a treatment modality when appropriate. However, the procedure requires a strict selection criteria, a skilled operant and meticulous surgical protocol to successfully transplant the tooth. We have used PRF and a physio-dispenser in both cases, which could have contributed to the successful treatment outcomes. However, the transplanted tooth warrants a long-term follow up to rule out post-transplant complications, such as inflammatory or replacement resorption.