Alternatives to Root Canal Treatment: Tooth Autotransplantation
Monty Duggal and Hani Nazzal
Although endodontic treatment is successful in most instances, some severely compromised teeth cannot be maintained in the long term. In children and adolescents, dental trauma can sometimes result in such severe damage to the tooth and supporting structures that tooth loss becomes inevitable. Also, a realistic long-term assessment of the prognosis of root canal treatment is required to be made when this treatment is carried out in a young patient, especially when the treated tooth has incomplete root development and a compromised crown/root ratio. Root fractures are often the medium term outcome of such root canal treated teeth. It is imperative that clinicians involved in the care of children with such injuries and faced with these clinical dilemmas undertake an interdisciplinary planning approach, which would give the patient a sustainable, biological long-term functional and aesthetic outcome. Autotransplantation is one such approach that should be considered to replace young permanent teeth where the long-term prognosis of endodontic management is not considered favourable. This chapter covers the rationale, indications, step-by-step treatment approach, and interdisciplinary planning that is required for a successful outcome of autotransplantation.
Tooth autotransplantation, also known as autologous tooth transplantation, is the controlled extraction and reimplantation of a donor tooth to a recipient site in the same person . Tooth autotransplantation is a viable treatment option in several clinical situations including tooth loss following dental trauma, management of traumatised teeth with poor prognosis, replacement of congenitally/developmentally missing teeth, management of malformed teeth such as macrodonts, dilacerated teeth, ectopic tooth development, and management of endodontically challenging cases, such as teeth with dens invaginatus. Autotransplantation is distinctly different from intentional replantation. Intentional replantation refers to the deliberate extraction of a tooth and after evaluation of root surfaces, endodontic manipulation, and repair, placement of the same tooth back into its original socket . In autotransplantation, a tooth that is usually unrestorable even with the most advanced endodontic management is extracted and replaced with a donor tooth from the same patient. Endodontic treatment in young children carried out in cases such as following dental trauma renders the tooth weak and often prone to coronal fractures. In clinical situations, where this might be the case, autotransplantation offers an excellent alternative with proven long-term outcomes. Although implants offer the possibility to replace teeth lost due to trauma, in children and adolescents, the earliest an implant can be placed is after most of growth and development is completed, which often means several years for the child without a natural anterior tooth. This has several implications in particular for bone maintenance where the natural tooth has been lost. An autotransplant placed through interdisciplinary planning during the period of growth and development gives the clinicians an opportunity to manage the loss of a tooth within the context of comprehensive orthodontic management and result in excellent long-term outcomes for the child. Autotransplantation can also be carried out in adults in certain specific indications such as loss due to tumour or to iatrogenic reasons, but gaining popularity of implants in adults has resulted in far fewer autotransplants being placed in adult patients.
The use of a biological treatment option such as tooth autotransplantation offers several advantages over other forms of prosthetic tooth replacement techniques, such as the use of removable partial dentures, fixed prostheses including minimal preparation bridges, orthodontic space closure followed by tooth camouflage, and implant placement (Figure 25.1).
25.2 Indications for Autotransplantation
Autotransplantation is a versatile technique that can be used in several challenging clinical situations such as:
- Teeth of poor prognosis
- Severe dento-alveolar trauma leading to:
- Root resorption
- Root fracture
- Dilacerated teeth that would not erupt even with orthodontic movement
- Failed root canal treatment in which retreatment cannot be performed or has technical challenges
- Severe dento-alveolar trauma leading to:
- Ectopic teeth
- Cleft lip and palate
25.3 Advantages and Disadvantages of Tooth Autotransplantation
By far, the main advantage of the tooth autotransplantation technique lies in the presence of a natural tooth with healthy periodontal ligament and in most cases the pulp tissues, which affords the possibility for a more natural tooth appearance and allows orthodontic tooth movement with associated bony growth. Indeed, early autotransplantation of immature teeth, followed by orthodontic extrusion, can facilitate bone formation and bony infill in deficient areas  (Figure 25.2). In addition, transplanting a mature tooth, with healthy periodontal ligament in an edentulous area can help preserve alveolar bone. Furthermore, the natural tooth appearance, offered by tooth autotransplantation, is usually associated with a good level of patient satisfaction as shown by Czochrowska et al.  and Shargill et al. .
Several limitations and disadvantages of tooth autotransplantation, however, do exist; therefore, careful case selection and patient informed consent are crucial for the success and acceptance of this technique. Such disadvantages include:
- The need for multiple dental appointments over an extended period of time, therefore, requiring patient’s/parent’s motivation and compliance.
- The high costs associated with such treatment.
- The impact of the multiple dental appointments on parents’ work commitments and children’s education.
- The need for surgical and bone manipulation; therefore, in some cases, sedation or general anaesthesia is needed, especially for children. In some older children or adults, local analgesia alone could be used for the procedure depending upon the cooperation and levels of anxiety.
Therefore, careful case selection and informed consent should be obtained before such treatment could be offered.
25.4 The Role of Interdisciplinary Team Planning
Successful tooth autotransplantation requires careful case assessment and planning by a team comprising orthodontists, paediatric dentists, oral surgeons, endodontists, and/or restorative dentists . Adopting a multidisciplinary approach, in which the patient is seen individually by different specialists, is disruptive to patients/parents and increases the cost of such treatment on patients/parents and service providers. In addition, the ability of team members to exchange ideas and discuss plans is usually compromised using this approach. On the contrary, adopting an interdisciplinary approach, in which the patient is examined simultaneously by the relevant teams, helps reduce cost and effort and improve communication amongst team members and effective debating of different available treatment plans.
Patients requiring tooth autotransplantation should be seen by the autotransplantation interdisciplinary team as early as possible. This early assessment would a) allow transplantation of immature teeth with incomplete root development, which is known to have a higher success rate, b) facilitate pre-autotransplantation orthodontic management in certain cases, and c) allow pre-transplantation bone management at the recipient site.
25.5 Pretransplantation Bone Management
Preservation of teeth, at the recipient site, is likely to help maintain bone height and width in addition to reducing the need for complete socket preparation. Tooth/bone preservation could, therefore, result in a less traumatic/complex autotransplantation surgery, which could reduce complications and failure . Where tooth preservation is not possible, as a result of replacement resorption or infection related resorption, maintaining bone at the recipient site should be a priority.
Replacement resorption of traumatised teeth can result in infraocclusion with associated bone defect. In such situations, decoronation of ankylosed infraoccluded teeth should be considered in order to prevent further bone loss especially in growing children (before the age of 10 years, or before the growth spurt) [8, 9]. Decoronation is performed as follows (Figure 25.3):
- Following administration of local analgesia, a mucoperiosteal flap is raised. The flap design (envelop, three or four corner flaps) is dependent on the case, number of teeth involved, and proximity of adjacent teeth.
- Root canal fillings and/or intracanal medicament should be removed before induction of intracanal bleeding and clot formation. This step aims at induction of future internal replacement resorption .
- The tooth crown is then carefully decoronated using a surgical bur with a straight handpiece or high speed handpiece with a tapered diamond bur with extreme care in order to prevent any damage to adjacent teeth.
- A surgical bur is then used to reduce the remaining root to a level of 2 mm apical to the adjacent alveolar bone.
- Primary closure of the mucosa is then performed in order to encourage soft tissue healing and bone apposition.
Decoronation, however, is not recommended in cases with uncontrolled infection or infection related resorption . In such cases, early extraction of such teeth is recommended in order to prevent unnecessary bone loss and damage to adjacent teeth. Bone management, using dento-osseous osteotomy, bone grafting, and/or orthodontic tooth movement in order to develop bone, could be utilised.
25.6 Case Selection
In addition to patient motivation and understanding of the risk/benefits of tooth autotransplantation, patients should be examined carefully by an orthodontist for availability of a donor tooth, and by the surgical team for suitability of the donor tooth and the recipient site.
25.6.1 Availability of a Donor Tooth
Orthodontic assessment is essential as tooth autotransplantation is usually part of an orthodontic treatment plan. Most transplantation cases involve a pre- and/or post-transplantation orthodontic treatment. Pretransplantation orthodontic management might involve one or more of the following objectives :
- Space maintenance for some time until autotransplantation is suitable
- Space creation at the recipient site (Figure 25.4)
- Staged extractions to create space for the transplanted teeth
- Root alignment of teeth adjacent to the recipient site
- Treatment of crowding at the recipient site
- Correction of centreline discrepancies
- Overbite reduction to prevent traumatic occlusion of the transplanted tooth
- Overall orthodontic management such as use of functional appliance therapy in some cases