In medical science, transplantation refers to transferring tissue or organ(s) from one site to another. Auto-transplantation of teeth involves the surgical transplantation of a tooth or teeth from one site in the mouth to another in the mouth of the same individual. The auto-transplantation procedure has been practised for many years to restore the missing teeth or replace the teeth with poor prognosis, with varying degrees of success. Auto-transplantation of the single-rooted premolars has been considered to substitute the traumatically lost central incisor(s) and congenitally missing lateral incisor(s). However, recent long-term reports of its success in orthodontic patients have generated significant interest, especially in young subjects with congenitally missing teeth or traumatic avulsion situations.

The auto-transplanted tooth is considered a better substitute than an implant for its biological behaviour of the periodontal apparatus and hard tissues. An auto-transplanted tooth undergoes physiological attrition and lifelong mesial migration, a biological necessity with ageing, like any other natural tooth in the mouth. Auto-transplanted teeth can preserve the alveolar ridge.

Andreasen et al. reported more than 90% survival rates in a comprehensive study. The observation period and survival are 1–25 years, with a mean of 10 years by Schwartz et al.

In a case study by Watanabe et al., a 29-year-old Japanese woman who had received orthodontic treatment underwent the extraction of her maxillary left first premolar after 32 months of orthodontic therapy. The extracted tooth was subsequently transplanted to the first molar region of the mandibular left molar region. A follow-up examination was conducted after transplantation. Radiographic and clinical assessments revealed no abnormalities 13 years and 9 months post-transplantation.

The first dental auto-transplantation was reported by Fong in 1953. Since then, various surgical techniques and protocols have evolved and introduced in the literature. ^, With clinicians working to create a standardised protocol and attempting to report success on long-term follow-up, auto-transplantation is gaining much attention as an alternative to implant prostheses for missing or poor prognosis teeth replacement. ^,

The indications for auto-transplantation of teeth include :

• 1.

  Pre-mature and traumatic tooth loss, especially at a younger age. Commonly involved teeth are maxillary central incisors.

• 2.

  Congenitally missing teeth, for example, maxillary lateral incisors where orthodontic space closure is ruled out.

• 3.

  Alignment of an impacted or ectopic tooth which cannot be aligned with conventional orthodontic methods.

• 4.

  Replacement of teeth with poor prognosis and developmental dental anomalies.

• 5.

  Transplantation of orthodontically indicated tooth for extraction, for example, a premolar to substitute anchor molar or a tooth with poor prognosis.

Auto-transplantation of the impacted and ectopic erupted teeth may be an alternative and faster treatment option for patients who do not want a long period of orthodontic treatment and in patients with questionable prognosis. This may be true in the case of adult patients who refuse to undergo orthodontic treatment or in situations where the conventional orthodontic treatment procedure alone is insufficient.

Auto-transplantation may also be helpful in premature or traumatic loss of teeth, especially in younger patients. Zachrisson reported that the maxillary incisors, the most frequently involved teeth in trauma, were replaced with mandibular second premolars in young patients with avulsed front teeth.

The most common teeth for auto-transplantation are premolars, canines, incisors and third molars. Premolars, especially the mandibular second premolars, are preferable for the maxillary incisor region due to their morphology, size and single root canal. Table 77.1 summarises the indications for auto-transplantation.

Proper case selection is the first and significant step in the success of auto-transplantation. The patient must have a suitable donor tooth (teeth) and recipient site(s) for transplantation.

The recipient site requirements are:

• 1.

  Sufficient space

  • If the available mesiodistal space for transplanting teeth is insufficient, orthodontic treatment should be considered to restore arch length.

• 2.

  Adequate volume of alveolar bone at the recipient site (mesiodistally, buccolingually and in height).

• 3.

  Absence of pathology or local inflammation.

• 4.

  The satisfactory alveolar bone at the recipient site, covered with attached keratinised gingiva, is essential for stabilising transplanted teeth.

• 5.

  No systemic disorders.

• 6.

  Good oral hygiene, willingness for regular dental check-ups and compliance with treatment.

The donor teeth requirements are ^, :

• 1.

  Teeth with open apex are preferable. The stage of root development is critical for successful auto-transplantation. Studies show a higher success rate when the root development of the donor tooth is one-half to two-thirds.

• 2.

  Vital and intact periodontal ligament.

• 3.

  Atraumatic extraction of donor tooth/teeth.

• 4.

  A tooth with abnormal root morphology is contraindicated.

The clinical steps are summarised as follows:

• 1.

  Clinical evaluation of the donor and recipient site.

• 2.

  Pre-operative radiographic evaluation of the donor’s tooth and the recipient site. If required, additional 3D radiography and evaluation are performed to estimate root morphology shape and dimensions, which guides in the preparation of the recipient socket.

The surgical procedure involves preparing the recipient site, creating a surgical flap and using surgical drills to create a socket of the appropriate root size for the tooth being transplanted. The donor’s tooth is carefully extracted, with particular attention given to preserving as much of the periodontal ligament as possible. The donor’s tooth should then be fitted into the prepared recipient site with gentle pressure to ensure a good fit in the socket. If necessary, further preparation of the recipient site is carried out, and the donor’s tooth is temporarily returned to its original socket to minimise the time spent outside the socket.

A 3D-printed replica could greatly help create an exact donor site. Such a protocol minimises surgical trauma and preserves periodontal ligament (PDL) during the trial fitting of the donor into the recipient site. ^, The extraction of the hopeless tooth at the recipient site should be delayed until transplantation to maximise the preservation of the PDL cells at the socket wall after atraumatic extraction.

Ashkenazi et al. demonstrated how cone beam-computed tomography (CBCT) and 3D computer simulations can be used to plan the optimal position and size of an artificial socket at the recipient site. This considers the thickness of the labial bone and the proximity of adjacent roots. They used a replica of the donor premolar to ensure the socket was prepared and oriented correctly before the donor’s tooth was extracted and replanted at the recipient incisor site. This approach is likely to improve the procedure’s accuracy and prognosis.

Hou et al. presented data on patients in a wide age range of various auto-transplantations, where they compared conventional radiographic and clinical protocol with CBCT-derived morphology of the donor’s tooth in facilitating pre-operative extraction of the donor’s tooth.

It is important to place the donor’s tooth with the same biological width of the gingiva as naturally erupted teeth. Following this, the donor’s tooth is secured with sutures. A close and secure fit between the flap and the donor’s tooth is crucial for the successful transplantation of the tooth. Finally, the transplanted tooth/teeth are secured with a splint.

The potential for orthodontic tooth movement of auto-transplanted teeth provides a greater advantage over the implant prosthesis. Paulsen et al. suggested orthodontic tooth movement can be initiated 3–9 months after transplantation, after periodontal healing, but before total pulp canal obliteration. Mensink et al. evaluated premolar auto-transplantation’s success and survival rate and reported that 98% of transplanted premolars are successfully aligned using orthodontic forces. The orthodontic movement of these transplanted teeth had been initiated 3 months after the procedure.

For the multiple congenitally missing teeth, auto-transplantation presents an excellent treatment alternative to minimise the need for prosthetic restoration in conjunction with orthodontic space closure. Fig. 77.1 depicts a congenital absence of five teeth, including bilateral maxillary lateral incisors, bilateral maxillary canines and the mandibular right first premolar. The mandibular left second premolar, extraction of which was required for orthodontic space closure, was successfully transplanted in the position of the maxillary left lateral incisor.

A case of congenital absence of five teeth, including bilateral maxillary lateral incisors, bilateral maxillary canines and the mandibular right first premolar. This case was successfully treated by auto-transplanting the mandibular left second premolar to the position of the maxillary left lateral incisor. The maxillary right deciduous lateral incisor was retained to maintain arch length for future restoration after its exfoliation. (A) Pre-treatment intraoral photographs. (B) Post-treatment intraoral photographs. (C) Pre-treatment panoramic radiograph. (D) Post-treatment panoramic radiograph.

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