Dental autotransplantation as a alternative treatment for the loss of permanent anterior teeth in children

ABSTRACT Introduction: Autotransplantation is defined as the surgical movement or transposition of a tooth from its original site to a recipient alveolus, in the same patient. It has high success rates when performed within predefined parameters. Objective: This study aims to describe the advantages of a dental autotransplantation protocol based on a multidisciplinary approach and using cone beam computed tomography, computer-aided planning, and rapid prototyping of the donor tooth, enabling the preparation of a surgical guide and postoperative protective plate. This article discusses the indications and contraindications for autotransplantation, as well as the selection criteria for the tooth to be transplanted and the transoperative care essential for its success. The parameters for post-operative control are described, in addition to the variables of success and failure to be considered. Conclusions: When analyzing the treatment options available for children with anterior tooth loss and the psychosocial impact on these patients, autotransplantation is considered not only an alternative treatment, but the only viable option for their functional, aesthetic, and social reestablishment.


INTRODUCTION
Autotransplantation is defined as the surgical movement or transposition of a donor tooth from its original site to a recipient alveolus in the same patient.
This process consists of a biological procedure in which teeth, especially in the germinative phase, have the ability to enhance and induce alveolar bone growth, 1 thus allowing the restoration of aesthetics and balance of the oral cavity by means of a natural tooth of the patient. 2 In an area of tooth loss, the initial possibilities for the replacement of this element would be: osseointegrated implants, fixed or removable prostheses, orthodontic space closure and dental autotransplantation. Each of these options has its indication and recommended timing for execution (Fig 1).
Autotransplantation is considered a good treatment option in cases of tooth loss due to trauma or anodontia in growing patients. 3 In addition to dental autotransplantation, the rehabilitation of a pediatric patient with tooth loss can be done orthodontically, by closing the space corresponding to the lost tooth. Another option would be the use of removable prostheses, or prostheses over temporary implants. In cases where Ambrósio MFS, Cançado RP, Oliveira BCG, Masioli MA, Cunha DL -Dental autotransplantation as a alternative treatment for the loss of permanent anterior teeth in children space closure is performed, permanent aesthetic limitations will occur. The use of removable prostheses has been proven to lead to poor quality of life in individuals in this age group.
Treatment involving dental implants become limited by the continuous dentoalveolar development of patients in active growth phase, since the implants do not follow the eruption of neighboring teeth. 4 Consequently, autotransplantation becomes an interesting alternative for these patients. Ambrósio MFS, Cançado RP, Oliveira BCG, Masioli MA, Cunha DL -Dental autotransplantation as a alternative treatment for the loss of permanent anterior teeth in children 6 The differences between dental transplants and dental implants are cited in Table 1.
Dental trauma is the second most frequent cause of pediatric dental consultation. 3 Bauss et al. 5 reported the incidence of trauma in permanent incisors and found that 10.3% of their sample had a history of trauma on these teeth. The highest prevalence of dental trauma occurred between 11 and 15 years of age, and most of them were in the mixed dentition. In this study, 79.6% of the teeth affected by trauma were maxillary central incisors. The authors reported a statistically significant prevalence of trauma to these teeth in patients with increased overjet, with or without adequate lip coverage. This becomes extremely relevant when we note that the Brazilian population has a prevalence between 36 to 40% of dental Class II individuals 6,7 . In addition to altered physiognomy, patients affected by missing anterior teeth routinely present malocclusions associated with such absences. 8,9,10 The success of autotransplantation is quite sensitive in relation to its indication and technique. This sensitivity has caused this procedure to go through moments of popularity and oblivion throughout history. The multidisciplinary treatment with the participation of an endodontist, a surgeon, a professional of aesthetics and an orthodontist increases the rate of satisfaction with the treatment, because it leads to a result both functionally and aesthetically satisfactory.
In this context, patients with missing teeth can undergo dental autotransplantation, but attention should be paid to the correct indication of the procedure. Important factors must be evaluated, such as the availability of a tooth for autotransplantation, the presence of space for rehabilitation, the presence of alveolar bone tissue in the recipient site, the stage of development of the tooth to be autotransplanted, and the general and oral health status of the patient.
Dental autotransplantation is also a solution for teeth in which endodontic treatment has failed, since the primary goal of endodontic treatment is the prevention and resolution of pulpal and periapical pathologies, to restore healthy peri-radicular tissues. 4   With the use of the printed prototype of the donor tooth, it is possible to prepare the alveolus before extracting the transplanted tooth from its original site Table 2A: Essential requirements for surgical procedure success. Table 2B: Essential requirements for the success of the surgical procedure.

IV Periodontal ligament cannot be injured
The cells of the periodontal ligament, through its differentiation, will be responsible for healing of the tooth in the alveolus V Preserving the cementum Avoids the risk of internal resorption Ambrósio MFS, Cançado RP, Oliveira BCG, Masioli MA, Cunha DL -Dental autotransplantation as a alternative treatment for the loss of permanent anterior teeth in children 12 tooth space, translating into better aesthetics, chewing, speech and dental arch integrity. 11,12 Rohof et al. 8 stated that current literature evidence on autotransplantation of teeth with incomplete root formation shows favorable survival and success rates, with low complication rates, indicating that it is a reliable treatment option. However, complications do exist, and the most common after autotransplantation include: ankylosis, root resorption, pulpal necrosis, and hypermobility. 8,13 According to Ravi Kumar et al., 14  From this documentation, initially a facial and dental diagnosis of the patient is performed, identifying malocclusions and the need or not for treatment. The identification of the individual's facial and dental pattern will help in determining which tooth will be used for autotransplantation, since the extraction of this tooth will be part of a global orthodontic treatment plan.
Not understanding this essential premise for a successful autotransplantation has been a ongoing cause of dissatisfaction with autotransplanted teeth in the past. Now it will be reported, for illustrative purposes, the clinical case of a male patient, 11 years and 3 months old, with history of tooth #21 avulsion, due to a fall from a toboggan in a water park. He was referred to a dental clinic, where it was decided to perform dental autotransplantation, since the reimplantation was not possible because the tooth was not found (Figs 3 and 4, Table 3).

DIAGNOSIS AND ORTHODONTIC TREATMENT PLAN
The patient presented a Class II in Steiner analysis, with well positioned maxillary incisor and protruded mandibular inci-  Subsequently, a 3D surface mesh of the donor tooth and the recipient site was created and stored as a standard triangulation language file (segmented stereolithography, STL) (Fig 5).
These files were imported into VistaDent 3D Pro 2.1 software.  In the segmentation mode, the premolars that could be chosen as donor tooth were evaluated by the orthodontist and surgeon, and together with the STL file of the recipient site and the iTero Element Scanner ® intraoral scan file, were transferred to the planning mode, so that accurate guides could be fabricated (Fig 6).  This analysis was performed for teeth #35 and #45, to select the most appropriate element for the recipient alveolus. As previously reported, both elements were in Nolla's stage 8, therefore, with a degree of root development suitable for treatment.
The adaptation of the teeth prototypes was tested in the target alveolus using the planning software, and the prototype of tooth #45 proved to be more effective, and was therefore selected. Subsequently, the surgical guide was made and tested, which was used during the transoperative phase (Figs 7 and 8).  This plate was kept for 30 days (Fig 9).

FOLLOW-UP OF AUTOTRANSPLANTED TOOTH
The proposal for clinical follow-up consists of performing periapical radiographs every 3 months in the first year, a CT scan at 6 months, and serial periapical radiographs annually, for up to 5 years.
Reshaping of the transplanted tooth was performed one year and three months after the surgical procedure. The cases performed within this protocol were reshaped with a minimum of 12 months after the surgical procedure. This time is longer than that found in most of the literature. We consider that the restoration procedure leads to some degree, even if small, of trauma to the transplanted tooth, and therefore we postponed whenever possible this reshaping (Fig 10). The restorative process is performed in a conventional manner, using acid etching, adhesive and light-cured composite resin.
An initial wear of the buccal and palatal aspects is performed with a diamond bur, without previous local anesthesia, for better reshaping (Fig 11). At each post-transplantation consultation, an evaluation of the success and survival of autotransplanted tooth is performed.
We followed the control parameters for autotransplanted teeth defined by Shahbazian et al. 17 The following clinical parameters should be evaluated at each control visit: sensitivity, color, mobility, percussion sensitivity, percussion tone, probing depth and gingival status of the transplanted tooth, in addition to radiographic parameters used to evaluate signs of canal obliteration, overall status of the periradicular area, root length and growth, crown-to-root ratio and root resorption.
A successful autotransplantation is defined as: the transplanted tooth has normal clinical and radiographic findings, with absence of ankylosis, no progressive resorption or infection; a crown-to-root ratio close to normal; normal mobility and gingival contour; a good level of fixation and normal gingival pocket depth (Fig 12). An autotransplantation is defined as a failure when: at control, the tooth has already been extracted, when it has an unacceptable clinical appearance, with persistent mobility, ankylosis, progressive resorption or infection.
Autotransplanted tooth survival is defined as the transplanted tooth still being present at that control appointment, with or without meeting success criteria.

CONSIDERATIONS
The success rate of the autotransplantation procedure is well The case reported here was performed by an experienced surgeon using an atraumatic technique, and an acetate plate was used postoperatively in order to protect the transplanted tooth against oscillating occlusal contacts in the first month after the procedure.
In addition, conventional sutures were preferred for fixation, allowing this physiological mobility during the fixation period.
According to Zachrisson et al., 23  The orthodontist's role is to make the diagnosis and establish the treatment plan aiming not only to replace a lost tooth, but to obtain a physiological and stable occlusion in the long term.

CONCLUSION
From the present case report, it is possible to conclude that autotransplantation is a viable option for the replacement of teeth lost by trauma in the mixed dentition. The technique for this procedure is sensitive, but can lead to a high success rate, especially if virtual planning using prototypes is used. A multidisciplinary approach should be adopted, to achieve the best result for the patient -mainly, the role of the orthodontist to obtain a physiological and stable occlusion in the long term should be emphasized. Randomized clinical trials should be the focus of future studies.
When we take into account the treatment options available for children with anterior tooth loss and the impact of these alternatives on the psychosocial context in which this individual is inserted, we believe that autotransplantation is not only