Abstract
The aim of this study was to systematically review the prognosis of autotransplanted teeth followed up for a period of 6 years or more. A literature search was conducted in five databases and the eligibility criteria were established. The outcomes evaluated were the survival rate, percentage of abnormal mobility, pulpal conditions, and percentage of root resorption. The searches identified 1848 articles, and after evaluation against the eligibility criteria, six were included. Data related to outcome measures were extracted from the studies and a meta-analysis was performed. Survival rates ranged from 75.3% to 91% and the meta-analysis showed an effect size of 81% ( P < 0.0001). The percentage ankylosis ranged from 4.2% to 18.2% and the effect size was 4.8% ( P < 0.0001). Root resorption percentages ranged from 3% to 10% and the effect size was equal to 4% ( P < 0.0001). It was not possible to perform a meta-analysis of data on pulpal conditions and percentage of teeth with abnormal mobility. The results of this study showed the survival rate to be excellent, considering the observation period. The rates of ankylosis and root resorption, despite their low values, influence the prognosis of transplanted teeth.
Children and young adults may often exhibit congenitally missing teeth or early loss of teeth due to trauma or caries. The most common restorative options include bridges, implants, removable appliances, and space closure. Autotransplantation, a treatment option where a tooth is surgically moved from one site in the mouth to another in the same individual, is often overlooked as an alternative, although it is an effective treatment. Its value lies in the fact that it enables denture reconstruction using the most biocompatible material, which is the patient’s own tooth. However, tooth transplantation is often perceived as an unpredictable alternative by surgeons unfamiliar with the procedure.
In the 1960s, Slagsvold and Bjercke established a protocol for autotransplanting teeth at the University of Oslo in Norway. This included indications for transplantation, the surgical procedure, and follow-up guidelines. The predictability of the method was further supported by a long-term follow-up study, which showed that the transplanted teeth had a survival rate of 90% and generally did not differ from normal teeth two to four decades later.
Tooth transplantation has many benefits. It can be performed at an early age, when the incidence of trauma is high. Transplanted teeth can be moved orthodontically and retain the potential to induce alveolar bone growth during the eruption process ; furthermore, the formation of a functional periodontal ligament allows eruption of the tooth, promoting bony infill at deficient sites, and the gingival contour is often superior to that achieved with prosthetic alternatives.
However, there are some risks associated with this procedure. The oral surgeon must have considerable knowledge, skill, and patience, and a careful surgical procedure is essential in order to achieve a successful outcome. Failures after initial attempts at performing the procedure are almost always related to surgical complications or difficulties in removal of the graft from the donor site.
During donor tooth extraction, a total rupture of the neurovascular bundle and periodontal fibres occurs, and the success of autotransplantation depends on the tissue healing process after the surgery. Pulp healing is usually characterized by restoration of the canal contents, including the vascular and nerve supply. The predictability of this healing response appears to be strongly related to the dimensions of the apical foramen. Favourable healing of the periodontal ligament depends on the number of viable cells preserved on the root surface. Successful healing may be expected if donor teeth are extracted with minimal mechanical damage to the periodontal ligament.
Damaged periodontal ligament areas and damaged parts of the root surface are attacked by a resorption process, which may affect the cementum and dentine. Thereafter, inflammatory resorption or surface resorption occurs, depending on the pulpal status and depth of the resorption cavity. Inflammatory resorption takes place if the resorption cavity penetrates the intermediate layer of cementum and comes into contact with the dentinal tubules that are in communication with infected necrotic pulp tissue. However, if the resorption cavity is shallow and does not penetrate the intermediate layer of cementum, a tooth with similar pulpal changes will elicit only surface resorption, as the intermediate layer of cementum will tend to arrest the diffusion of toxic elements. Inflammatory root resorption usually progresses until the root canal is exposed. In surface resorption, a new periodontal ligament space is established.
Ankylosis, another type of commonly observed root resorption, is caused by large injuries to the root surface of a donor tooth during surgery. In this situation, cells programmed to form bone begin attacking some areas of the root, resulting in resorption (like the adjacent bone). However, in the apposition stage, bone, and not dentine, fills the previously resorbed area.
Autotransplanted teeth are often evaluated in the first year postoperative. However, in order to assess the success of tooth autotransplantation, tissue healing processes and their evolution over the years should be examined, since this procedure is more frequently used in children and adolescents.
No systematic reviews assessing these outcomes over the long term appear to have been reported in the literature. In the present study, it was attempted to evaluate long-term survival rates, the degree of mobility, and the pulp and root conditions of autotransplanted teeth with different stages of root formation at the time of surgery.
Materials and methods
This systematic review is reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. The protocol was designed to answer the following PICO question (i.e. patient, problem or population, intervention, comparison, and outcomes): What are the survival rate, degree of mobility, and pulp and root conditions (outcomes) of autotransplanted (intervention) teeth (population) at least 6 years postoperatively?
An extensive literature search of five electronic databases was conducted: PubMed, Scopus, Web of Science, Lilacs, and The Cochrane Library. The search strategy was performed following the syntax rules of each database; the search protocol established for Medline (via PubMed) is shown in Table 1 .
| PubMed | ((tooth[ti] or teeth[ti]) and (transplantation, autologous[mh] OR autotransplantation[ti] OR autotransplanted[ti] OR transplantation[mh] OR transplantation[ti] OR transplanted[ti])) AND (tooth[mh] OR tooth[ti] OR teeth[ti] OR bicuspid[mh] OR premolar*[ti] OR incisor[mh] OR incisor*[ti] OR molar, third[mh] OR ‘third molar’[ti] OR ‘third molars’[ti] OR ‘wisdom teeth’[ti] OR ‘wisdom tooth’[ti] OR cuspid[mh] OR ‘canine teeth’[ti] OR ‘canine tooth’[ti] OR ‘maxillary canine’[ti] OR ‘mandibular canine’ OR molar[mh] OR molar*[ti]) |
The following filters were used in the search strategy: date (1990/01/01 to 2014/07/07) and species (humans) filters in PubMed, and only date (1990–2014) filter for the remaining four databases. The reference lists of relevant review studies were reviewed manually after the selection protocol to identify further potentially relevant articles.
The inclusion criteria were as follows: (1) controlled trials or prospective/retrospective studies; (2) studies reporting at least one of the following: survival rate, pulp condition, mobility, presence of ankylosis, and root resorption of autotransplanted teeth with complete or incomplete root formation; and (3) studies in which all patients were followed up for a period equal to or greater than 6 years.
The exclusion criteria were as follows: (1) case reports, case series, opinion articles, and review articles; (2) studies reporting autotransplanted teeth in patients with systemic diseases, syndromes, or cleft lip and palate; (3) animal studies; (4) studies examining cryopreserved teeth or teeth maintained in culture media; (5) studies reporting autotransplantation of teeth with a history of cysts, tumours, or trauma; (6) studies including sterilized teeth; (7) studies using membranes; (8) studies with intra-alveolar transplantation of teeth with root fractures; (9) studies with the presence of oro-antral fistulae; (10) studies examining tooth autotransplantation associated with maxillary sinus lifting; and (11) teeth subjected to intentional replantation for endodontic treatment. No restrictions on language were made.
First, the titles and abstracts of potential articles were analyzed and studies that did not meet the eligibility criteria were excluded. A full-text analysis was carried out in cases where the abstract was unavailable or suggested that the eligibility criteria were fulfilled. Each title and abstract was reviewed independently by two researchers (L.A.M. and R.R.N.), and the information obtained was compared. Inter-examiner disagreements were resolved in a consensus meeting with another author (O.V.V.).
The Methodological Index for Non-Randomized Studies (MINORS) was used to assess the quality of articles that met the eligibility criteria. Data directly related to measures of the outcomes of interest were recorded and extracted independently by two authors (L.A.M. and C.T.M.). Any disagreement between reviewers at this stage was resolved by discussion.
The outcomes evaluated were as follows: (1) percentage of transplanted teeth that were still present at the time of examination of the total number of transplanted teeth (survival rate), (2) percentage of abnormal mobility, (3) pulp conditions, and (4) percentage of root resorption.
A meta-analysis was performed using Comprehensive Meta Analysis software version 3.2 (Biostat, Inc., Englewood, NJ, USA). Events and the total sample were collected from the studies that reported them in order to achieve a combined effect size of proportion for evaluation of the survival rate and root resorption. A fixed-effects model was used for analysis as only a few studies were comparable. Heterogeneity among studies was recorded, and a sensitivity analysis was performed. Finally, forest plots showing the comparisons were created. Publication bias was assessed using a funnel plot.
Results
The electronic database searches identified 1848 titles and abstracts ( Fig. 1 ). Of these, 297 titles were duplicated and were, therefore, removed. All remaining titles and abstracts ( n = 1551) were analyzed, and 1490 did not meet the inclusion criteria. The full texts of 61 studies were assessed, and finally six articles that met the inclusion criteria completely were selected. No additional articles were found in the manual search.
One study, with a mean follow-up time of 6.2 years, did not provide the range (minimum and maximum follow-up). Attempts were made to contact the authors for the required data, but there was no response. Therefore, this study was not included in the systematic review. A detailed summary of the final selected studies is presented in Table 2 . This systematic review was based on prospective and retrospective studies due to the absence of controlled trials.
| Author | Study design | Number of patients | Number of teeth | Age range of patients, years | Donor tooth type | Root formation | Follow-up, years |
|---|---|---|---|---|---|---|---|
| Mendoza-Mendoza et al. (2012) | RS | 12 | 12 | 9–13 | Mx and Md premolars | 1/2, 3/4, and complete root length | 10–14 |
| Gonnissen et al. (2010) | RS | 59 | 73 | 11–46 | 67 Mx impacted canines; 3 Md impacted canines; 2 Md molars |
1/2 to 3/4, more than 3/4, complete root formation | 6–14 (mean 11) |
| Watanabe et al. (2010) | RS | 32 | 38 | 10–43 | Mx and Md incisors, premolars, and molars | Complete | 6.1–14.5 (mean 9.2) |
| Czochrowska et al. (2002) | RS | 28 | 33 | 8–15 | 2 Mx lateral incisors 10 Mx premolars 16 Md premolars 2 supernumerary teeth |
Incomplete | 17–41 (mean 26.4) |
| Paulsen and Andreasen (1998) Paulsen et al. (1995) |
PS | NR | 118 | NR | Mx and Md premolars | 3/4 to 4/4 root development with an open apical foramen | 6–18 (1998) 6–16 (1995) |
The studies of Paulsen et al. and Paulsen and Andreasen involved the same patients; however, some of the outcome measures examined were different and the follow-up period in the latter study was longer. In the study performed by Gonnissen et al., autotransplantations were basically used to correct the position of ectopically impacted canines. All other studies included used autotransplantation to replace missing teeth. Moreover, although Mendoza-Mendoza et al. defined their study as a case series, it was considered a retrospective study by the present authors and was included in this systematic review as such.
The survival rate, mobility rate, pulp condition, and root resorption rates from the individual studies are summarized in Table 3 .
| Author | Survival rate | Degree of mobility | Pulpal condition | Root resorption rate |
|---|---|---|---|---|
| Mendoza-Mendoza et al. (2012) | 83.3% | NR | Present teeth ( n = 10): 100% presented pulp obliteration | Replacement resorption : NR Surface resorption : present teeth ( n = 10): 10% Inflammatory resorption : overall cause of extraction of 2 teeth (16.7%) |
| Gonnissen et al. (2010) | 75.3% | Present teeth ( n = 55): 63.6% negative mobility 32.7% normal mobility 3.6% excessive mobility (Periotest) |
Non-endodontically treated present teeth (60%) ( n = 33): 3% positive result for cold test 12.1% positive result for electric pulp test 75.8% clear pulsatility 57.5% reduction in size or complete obliteration of pulp chamber |
Present teeth ( n = 55): 38.2% (34.6% external resorption and 3.6% internal resorption) Overall cause of extraction of 9 teeth (12.3%) |
| Watanabe et al. (2010) | 86.8% | Present teeth ( n = 33): 18.2% negative mobility (Periotest) |
The quality of root filling was significantly correlated with the success rate (no abnormal findings) | Replacement resorption : present teeth ( n = 33): 18.2%; overall cause of extraction of 3 teeth (7.8%) Surface resorption : NR Inflammatory resorption : present teeth ( n = 33): 3%; overall cause of extraction of 1 tooth (2.63%) |
| Czochrowska et al. (2002) | 91% | NR | In the teeth where pulp obliteration was analyzed (the group compared to contralateral teeth, n = 11), 100% showed this alteration | Replacement resorption : present teeth ( n = 30): 6.7%; overall cause of extraction of 2 teeth (6%) Surface resorption : NR Inflammatory resorption : NR |
| Paulsen and Andreasen (1998) Paulsen et al. (1995) |
NR | NR | 16 teeth (13.5%) showed pulp necrosis and 1 (0.8%) had partial pulp necrosis | Replacement resorption : present teeth ( n = 118): 4.2% Surface resorption : in the teeth submitted to orthodontic rotation (Paulsen et al. 1995) Inflammatory resorption : present teeth ( n = 118): 3.4% |
The assessment of the quality of articles, in accordance with MINORS, is shown in Table 4 . An item was scored as ‘0’ when not reported, ‘1’ when it was inadequately reported, and ‘2’ when it was adequately reported. The articles were classified according to their methodological quality into low (>17), medium (≥10 to ≤17), and high risk of bias (<10). All studies selected were classified as having a medium risk of bias and were included in this investigation.
| Items of MINORS | Mendoza-Mendoza et al. (2012) | Gonnissen et al. (2010) | Watanabe et al. (2010) | Czochrowska et al. (2002) | Paulsen and Andreasen (1998) | Paulsen et al. (1995) |
|---|---|---|---|---|---|---|
| A clearly stated aim | 2 | 2 | 2 | 2 | 2 | 2 |
| Inclusion of consecutive patients | 2 | 2 | 2 | 2 | 2 | 2 |
| Prospective collection of data | 2 | 0 | 0 | 0 | 2 | 2 |
| Endpoints appropriate to the aim of the study | 2 | 2 | 2 | 2 | 2 | 2 |
| Unbiased assessment of the study endpoint | 0 | 0 | 0 | 0 | 0 | 0 |
| Follow-up period appropriate to the aim of the study | 2 | 2 | 2 | 2 | 2 | 2 |
| Loss to follow-up less than 5% | 0 | 0 | 0 | 0 | 0 | 2 |
| Prospective calculation of the study size | 0 | 0 | 0 | 0 | 0 | 0 |
| An adequate control group | 2 | 0 | 2 | 2 | 2 | 0 |
| Contemporary groups | 2 | 0 | 2 | 2 | 2 | 0 |
| Baseline equivalence of groups | 1 | 0 | 2 | 2 | 2 | 0 |
| Adequate statistical analyses | 0 | 2 | 1 | 1 | 0 | 0 |
| Total | 15 | 10 | 15 | 15 | 16 | 12 |
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