Autotransplantation of teeth: requirements for predictable success

The aim of this article is to summarize the biologic principles required for successful autotransplantation of teeth. Indications, armamentarium, technique and prognosis will be discussed.

Bioengineered teeth from cultured rat tooth bud cells

The recent bioengineering of complex tooth structures from pig tooth bud tissues suggests the potential for the regeneration of mammalian dental tissues. We have improved tooth bioengineering methods by comparing the utility of cultured rat tooth bud cells obtained from three- to seven-day post-natal (dpn) rats for tooth-tissue-engineering applications. Cell-seeded biodegradable scaffolds were grown in the omenta of adult rat hosts for 12 wks, then harvested. Analyses of 12-week implant tissues demonstrated that dissociated 4-dpn rat tooth bud cells seeded for 1 hr onto PGA or PLGA scaffolds generated bioengineered tooth tissues most reliably. We conclude that tooth-tissue-engineering methods can be used to generate both pig and rat tooth tissues. Furthermore, our ability to bioengineer tooth structures from cultured tooth bud cells suggests that dental epithelial and mesenchymal stem cells can be maintained in vitro for at least 6 days.

Functional tooth regeneration using a bioengineered tooth unit as a mature organ replacement regenerative therapy

Donor organ transplantation is currently an essential therapeutic approach to the replacement of a dysfunctional organ as a result of disease, injury or aging in vivo. Recent progress in the area of regenerative therapy has the potential to lead to bioengineered mature organ replacement in the future. In this proof of concept study, we here report a further development in this regard in which a bioengineered tooth unit comprising mature tooth, periodontal ligament and alveolar bone, was successfully transplanted into a properly-sized bony hole in the alveolar bone through bone integration by recipient bone remodeling in a murine transplantation model system. The bioengineered tooth unit restored enough the alveolar bone in a vertical direction into an extensive bone defect of murine lower jaw. Engrafted bioengineered tooth displayed physiological tooth functions such as mastication, periodontal ligament function for bone remodeling and responsiveness to noxious stimulations. This study thus represents a substantial advance and demonstrates the real potential for bioengineered mature organ replacement as a next generation regenerative therapy.

A microangiographic study of vascular changes in replanted and autotransplanted teeth of young dogs

The purpose of the present investigation was to study the revascularization process of the pulp of replanted and autotransplanted teeth with incomplete root development in dogs. A barium-sulfate injection method combined with contact microradiography was used. Ingrowth of apparently new vessels was seen during the first postoperative days. After 10 days, visible vessels were seen in the apical half of the pulp, and after 30 days, in the whole pulp. Branches and apparently also anastomoses between pulpal vessels were seen after 10 days but were especially numerous after 30 days. One hundred eighty days postoperatively, only one of fifteen teeth was devoid of visible vessels, indicating pulpal necrosis. Thirteen of the remaining fourteen teeth exhibited visible vessels throughout the entire length of the pulp. It seems, therefore, that replanted and autotransplanted teeth with open apices have a high potential for repair. The revascularization of the pulp appeared to occur mainly by ingrowth of new vessels. In some instances, however, anastomoses seemed to form to pre-existing vessels in the pulp.

Autotransplantation of human teeth. A life-table analysis of prognostic factors

In a retrospective study of a sample of 291 autotransplantations of human teeth carried out by 27 oral surgeons over a period of 25 years, the clinically and radiologically available factors at the time of surgery were analysed with reference to their prognostic relevance. Prognostically relevant factors related to loss of the transplanted teeth were determined by both univariate life-table analysis and multivariate Cox regression analysis. Of the 11 factors analysed in the Cox regression analysis, the following seemed to be prognostically relevant to loss or retention of the graft: developmental stage of the graft, age of the patient, donor tooth type, ectopia of the donor tooth, extraoral storage of the graft, and oral surgeon. In the present material, the prognosis of the grafts did not seem to be significantly influenced by such factors as prophylactic administration of antibiotics and fixation time. Using relevant parameters, it is possible to create a prognosis forecast for the individual patient. A case with a favourable set of parameters is shown.

A clinical follow-up study of 278 autotransplanted teeth

This open study was undertaken to investigate the outcome of autotransplanted teeth over a 6-year period. The subjects were 296 patients who underwent autotransplantation in the 6-year period September 1986-August 1992 and outcome was measured by considering root formation, occlusion, endodontal and periodontal complications. 18 patients were excluded because of inadequate notes or radiographs (n = 3) or because they were lost to follow-up (n = 15). The groups were divided into open apex and closed apex, and duration of follow up was 6 months-5 years. Aplasia was the indication for operation in 158 (77 percent) of the open apex group but only 10 (14 percent) of the closed apex group, whereas caries and associated disease was the most common in the latter (n = 45, 61 percent compared with 20, 10 percent). There were 24 complete failures, 12 in each group (p <0.01). Only 7 teeth in total developed full roots, and 159 showed incomplete growth. In the open apex group 112 teeth were in occlusal contact and 4 were extracted for severe infraocclusion. In the closed apex group there were 10 cases of mild infraocclusion, none of which required treatment. There were 7 cases of pulp necrosis in the open apex group, 4 of which required extraction. Two teeth in the closed apex group were extracted for endodontic reasons. Only 1 tooth (in the closed apex group) had to be extracted for periodontal reasons. Autotransplantation is a reliable method with a good prognosis for donor teeth with both open and closed apexes. The technique is applicable whatever the aetiology of the agenesis, and is worthy of consideration should there be a suitable donor tooth.

Tissue-engineered hybrid tooth and bone

Tooth loss accompanied by alveolar bone resorption presents a significant clinical problem. We have investigated the utility of a tissue-engineering approach to provide corrective therapies for tooth-bone loss. Hybrid tooth-bone tissues were bioengineered as follows. Tooth implants were generated from pig third molar tooth bud cells seeded onto polyglycolide (PGA) and polyglycolide-colactide (PLGA) scaffolds, and grown for 4 weeks in the omenta of adult rat hosts. Bone implants were generated from osteoblasts induced from bone marrow progenitor cells obtained from the same pig, seeded onto PLGA fused wafer scaffolds, and grown for 10 days in a rotational oxygen-permeable bioreactor system. The tooth and bone implants were harvested, sutured together, reimplanted, and grown in the omenta for an additional 8 weeks. Histological and immunohistochemical analyses of the excised hybrid tooth-bone constructs revealed the presence of tooth tissues, including primary and reparative dentin and enamel in the tooth portion of hybrid tooth-bone implants, and osteocalcin and bone sialoprotein-positive bone in the bone portion of hybrid tooth-bone constructs. Collagen type III-positive connective tissue resembling periodontal ligament and tooth root structures were present at the interface of bioengineered tooth and bone tissues. These results demonstrate the utility of a hybrid tooth-bone tissue-engineering approach for the eventual clinical treatment of tooth loss accompanied by alveolar bone resorption.

Clinical application of computer-aided rapid prototyping for tooth transplantation

The maintenance of healthy periodontal ligament cells in the donor tooth is one of the most important factors for successful tooth transplantation. This is achieved by minimizing the extraoral time during the surgical procedure. If a duplicate form of donor tooth could be obtained before extraction, it would be possible to precontour the recipient alveolar bone compatible with the donor tooth, and thereby reduce the extra-oral time of the donor tooth. We obtained a three-dimensional image with the real dimensions of the donor tooth from a CT Highspeed Advantage, allowing a life-sized resin model of the tooth to be fabricated. From 22 clinical cases, we achieved an average total transplantation time of 7.7 min. The average distance between the transplanted root surface and the alveolar bone from 12 available cases was 0.87 mm at the mesial cervix, 0.91 mm at the mesial apex, 0.98 mm at the distal cervix and 1.16 mm at the distal apex on the postoperative radiographs. Clinical data indicate that computer-aided rapid prototyping may be of value in minimizing the extra-oral time and possible injury to transplanted tooth during the process of autotransplantation.

Evaluation of the prognosis and causes of failure in 182 cases of autogenous tooth transplantation

OBJECTIVES

Autotransplantation is a viable option for treating missing teeth when a donor tooth is available. The aim of this study was to evaluate the prognosis in addition to the causes of failure in 182 autotransplanted teeth.

STUDY DESIGN

A total of 182 cases of autotransplantation were analyzed. All the transplants were performed according to a computer-aided rapid prototyping technique with an average extraoral time of 7.58 minutes. These cases were followed for 2 to 60 months after surgery. The prognosis was divided into 4 groups, complete healing, incomplete healing, uncertain healing, and failure. The initial stability, root resorption, and ankylosis were also analyzed.

RESULTS

Most transplanted teeth showed complete healing between postoperative 2 months and 8 months. The transplanted teeth with a good initial stability showed better initial healing than those with a poor initial stability. The average extraoral time was 7.58 min (range: immediately after extraction up to 25 min). There was no relationship (P > .05) between the extraoral time and either root resorption (4 cases, 2.4%) or ankylosis (18 cases, 10.7%) within this experimental time period. Nine cases (4.5%) failed.

CONCLUSION

This study showed a 4.5% failure rate during the short to intermediate observation period. Autotransplantation is a very useful method for replacing missing teeth, provided that the extraoral time and other factors are well controlled.

Applicability of autotransplantation in cases of missing upper anterior teeth

No immunologic problems are involved in autotransplantation, as they are in allotransplantation. One is justified in stating that the prognosis for autotransplantation of teeth is favorable, at least in young persons. In this report six cases are presented to demonstrate that autotransplantation can contribute to more satisfactory solutions to the problem of missing anterior teeth than can otherwise be achieved. It is difficult to form general rules regarding the indications for autotransplantation in such cases. Each case must be assessed on its own premises: the substitution need, the availability of a transplant, the long-term prognosis, and the advantages and disadvantages of a solution with autotransplantation versus solutions without autotransplantation. It should be admitted that the applicability of autotransplantation is limited. However, the therapist who realizes that the applicability in young patients is primarily a question of the availability of transplants may find that this is greater than he has previously realized.

Tooth transplantations: a descriptive retrospective study

The aim of the present study was to perform a retrospective study of autogeneously transplanted teeth in order to examine the influence of clinical criteria such as the type of the donor tooth, the root length at the time of transplantation, donor eruption stage and others on the overall success rate of the transplantation. The material of this study consisted of 194 patients in whom 273 teeth were transplanted. The mean age at the time of autotransplantation was 18.1 years with a standard deviation of 7.5 years. Transplantations were performed in two hospitals. The follow-up period varied from 15 days to 11 years, and the mean follow-up time was 3.8 years. 58/273 teeth showed one or other form of resorption, 37/273 teeth showed ankylosis, 30/273 showed no important changes in pulp chamber size, 104/273 showed major discoloration after transplantation, 92/273 teeth showed positive results for cold test after transplantation and 26/273 teeth showed clinically unacceptable pocket depth. Clinical and radiological evaluations were performed. An association was found between successful transplantation and donor tooth type (P<0.01), root length at the time of transplantation (P<0.0001) and recipient tooth site (P=0.03). There was a borderline association between successful transplantation and donor eruption stage (P=0.05). In conclusion, autotransplantation of teeth performed with a careful surgical procedure at the stage of 1/2-3/4 of their intended or expected root length can render a very useful service to patients.

Autotransplantation of teeth in cases with agenesis or traumatic loss of maxillary incisors

The purpose of this study was to investigate the prognosis of 50 consecutively autotransplanted teeth to the maxillary incisor region. Thirty-five were transplanted in cases of traumatic injuries, eleven in cases of agenesis and four in cases with impaction of maxillary canines. The average follow-up time was 7 years and 6 months (range 4-17 years). The transplants were examined clinically in respect of tooth vitality and radiographically in respect of root canal obliteration, periradicular changes, root formation, and root length. The results show a success rate of 82 per cent. It is concluded that the procedure of tooth transplantation has the advantage of maintaining or restoring alveolar bone volume and gives the opportunity to replace a missing tooth without involvement of neighbouring teeth as prosthetic abutments.

Bioengineered dental tissues grown in the rat jaw

Our long-term objective is to develop methods to form, in the jaw, bioengineered replacement teeth that exhibit physical properties and functions similar to those of natural teeth. Our results show that cultured rat tooth bud cells, seeded onto biodegradable scaffolds, implanted into the jaws of adult rat hosts and grown for 12 weeks, formed small, organized, bioengineered tooth crowns, containing dentin, enamel, pulp, and periodontal ligament tissues, similar to identical cell-seeded scaffolds implanted and grown in the omentum. Radiographic, histological, and immunohistochemical analyses showed that bioengineered teeth consisted of organized dentin, enamel, and pulp tissues. This study advances practical applications for dental tissue engineering by demonstrating that bioengineered tooth tissues can be regenerated at the site of previously lost teeth, and supports the use of tissue engineering strategies in humans, to regenerate previously lost and/or missing teeth. The results presented in this report support the feasibility of bioengineered replacement tooth formation in the jaw.

Factors influencing periodontal repair and regeneration

The purpose of the present study was to evaluate independently the regeneration capacity of a reduced periodontium, and the potential for new connective tissue attachment to a periodontally exposed root surface. A reduced periodontium was produced around a maxillary central incisor in two Rhesus monkeys using orthodontic elastics. The regeneration capacity of this reduced peridontium was investigated by extracting the periodontally involved tooth and transplanting into the socket the contralateral incisor which had a normal periodontium. The potential for new connective tissue attachment to a periodontally exposed root surface was evaluated by transplanting an exposed root into a normal periodontium. These exposed roots were the incisors extracted from the reduced peridontium. Control specimens were obtained by extracting and reimplanting or transplanting the remaining maxillary and mandibular incisors. Forty days after the experimental procedures, block sections were removed and prepared for histologic analysis. The exposed root surface that had been put into the normal periodontium was lined with epithelium interposed between root surface and alveolar bone. The normal root surface that had been put into the reduced periodontium had connective tissue reattachment in the periodontal ligament and supracrestal regions. Areas of ankylosis and root resorption were present in all specimens, as was new cementum in the periodontal ligament region. The results indicated that root surface alterations, rather than presence of a reduced periodontium, inhibited new connective tissue attachment.

Autotransplantation of teeth with incomplete root formation: a systematic review and meta-analysis

OBJECTIVES

The objective of this systematic review and meta-analysis was to determine the rates of survival and success and the complications related to autotransplantation of teeth with incomplete root formation. Additionally, we attempted to identify the prognostic factors that influence the outcome of tooth autotransplantation.

MATERIALS AND METHODS

A literature search for all data published until July 2016 was conducted. Inclusion and exclusion criteria were specified. Risk of bias was assessed with the Newcastle checklist. Meta-analysis was performed by using the DerSimonian-Laird random effect model. The 1-, 5-, and 10-year survival rates and the weighted estimated survival, success, and complication rates per year were calculated.

RESULTS

Thirty-two studies were included for analysis. The survival rates reported after 1, 5, and 10 years were 97.4, 97.8, and 96.3%, respectively. The annual weighted estimated survival rate (98.2%), success rate (96.6%), and complication rates in terms of ankylosis (2.0%), root resorption (2.9%), and pulp necrosis (3.3%) were analyzed. No firm conclusions could be drawn with respect to the prognostic factors due to insufficient evidence of high quality.

CONCLUSION

The survival and success rates of autotransplantation of teeth with incomplete root formation were high (> 95%), with a low rate of complications (< 5%).

CLINICAL RELEVANCE

Current evidence from the literature on autotransplantation of teeth with incomplete root formation shows favorable survival and success rates and low complication rates, indicating it is a reliable treatment option.

Vascularization of engineered teeth

The implantation of cultured dental cell-cell re-associations allows for the reproduction of fully formed teeth, crown morphogenesis, epithelial histogenesis, mineralized dentin and enamel deposition, and root-periodontium development. Since vascularization is critical for organogenesis and tissue engineering, this work aimed to study: (a) blood vessel formation during tooth development, (b) the fate of blood vessels in cultured teeth and re-associations, and (c) vascularization after in vivo implantation. Ex vivo, blood vessels developed in the dental mesenchyme from the cap to bell stages and in the enamel organ, shortly before ameloblast differentiation. In cultured teeth and re-associations, blood-vessel-like structures remained in the peridental mesenchyme, but never developed into dental tissues. After implantation, both teeth and re-associations became revascularized, although later in the case of the re-associations. In implanted re-associations, newly formed blood vessels originated from the host, allowing for their survival, and affording conditions organ growth, mineralization, and enamel secretion.

Autotransplantation of teeth: is there a role?

Autotransplantation of teeth, if carried out successfully, ensures that alveolar bone volume is maintained due to physiological stimulation of the periodontal ligament. Autotransplantation has been carried out for many years, but with varying success rates. As a result, it is seldom regarded as an appropriate treatment option for patients with missing teeth especially with the continued development of osseo-integrated implants. Since placement of osseo-integrated implants in growing alveolar bone is contra-indicated, transplantation of available teeth remains a suitable choice for replacing missing units in the young patient. The role of autotransplantation of teeth in several clinical situations, the clinical techniques involved and factors influencing success of the transplant are discussed. The aim of this paper is to underline the evidence based principles for successful autotransplantation and present the technique as a viable treatment option in present day orthodontic practice.

Transplanting teeth successfully: autografts and allografts that work

This article suggests tooth transplantation as an alternative to other restorative options. The 10-year success rates for autografts--teeth moved from one location to another in a patient's mouth--range from 60 percent to 95 percent. Allografts, teeth moved from one person to another, are less successful. The authors report on one case of each type of transplant.

Dental treatment strategies in cleidocranial dysplasia

Based on the findings of our recent longitudinal study on the abnormalities of the dentition in cleidocranial dysplasia (CCD), a hypothesis has been proposed, which makes it possible to predict time of onset of formation of supernumerary teeth and their location in the jaws. It was found that a diagnosis should be made early so that formation of supernumerary teeth can be diagnosed and early intervention undertaken. It should be possible to diagnose supernumerary incisors at about 5-7 years of age and supernumerary canines and premolars a few years later. When root length of the normal permanent teeth has reached about one third of its final length, the overlying supernumerary teeth should be removed, together with overlying bone and primary teeth. In regions where no supernumerary teeth are formed, eruption may also be improved by removal of the primary teeth and surgical exposure of the underlying permanent teeth. Conventional orthodontic treatment and eventually autotransplantation of teeth may still be necessary in the future, but it can be anticipated that the new strategy, with much earlier intervention, will materially reduce the extent of surgical and orthodontic interventions, which have previously been of extremely long duration, tedious to the patients and often of limited success.