Autotransplantation of teeth using computer-aided rapid prototyping of a three-dimensional replica of the donor tooth: a systematic literature review

Abstract

This systematic review provides an overview of studies on autotransplantation techniques using rapid prototyping for preoperative fabrication of donor tooth replicas for preparation of the neo-alveolus. Different three-dimensional autotransplantation techniques and their treatment outcomes are discussed. The systematic literature search yielded 19 articles that satisfied the criteria for inclusion. These papers described one case–control study, four clinical observational studies, one study with a clinical and in vitro part, four in vitro studies, and nine case reports. The in vitro studies reported high accuracy for the printing and planning processes. The case reports all reported successful transplantation without any pathological signs. The clinical studies reported a short extraoral time of the donor tooth, with subsequent success and survival rates of 80.0–91.1% and 95.5–100%, respectively. The case–control study reported a significant decrease in extraoral time and high success rates with the use of donor tooth replicas. In conclusion, the use of a preoperatively designed surgical guide for autotransplantation enables accurate positional planning, increases the ease of surgery, and decreases the extraoral time. However, the quality of the existing body of evidence is low. Further research is therefore required to investigate the clinical advantages of this innovative autotransplantation technique.

Autotransplantation of teeth refers to the surgical transposition of a donor tooth from a donor site to a surgically prepared artificial socket (recipient site) within the same individual. Several diverse indications favour physiological tooth replacement. Primary indications for autotransplantation include agenesis of teeth, premature and/or traumatic tooth loss, and heavily damaged teeth . The most common procedure involving autotransplantation probably is the replacement of an absent mandibular premolar by a maxillary premolar in young patients . This treatment option is particularly useful when orthodontic extraction therapy of maxillary premolars is indicated . Ideally, autotransplantation of teeth should be performed when root formation is 50–75% of the expected complete root development . This condition corresponds with a radiographically open apex of at least 1 mm, which allows revascularization of the pulp chamber and continued root growth . The success and survival rates of transplanted teeth are generally high, with reported rates of 79–100% and 57–100%, respectively, after autotransplantation by conventional techniques . Success is defined as autotransplantation with direct physiological implantation of the donor tooth, without any signs of pathology or need for additional procedures. Survival is defined as persistence of the transplanted tooth (despite possible compromised function, aesthetics, or development) .

The most important considerations for successful tooth transplantation are preservation of the healthy periodontal ligament cells and good tissue adaptation. These factors are influenced by surgical aspects such as the number of fitting attempts of the donor tooth, distance between the new alveolus and the root of the donor tooth, extra-alveolar time, skill of the surgeon, and level of trauma during donor tooth extraction .

In conventional autotransplantation techniques, the extracted donor tooth serves as a template for preparation of the new tooth socket at the recipient site. This involves manipulation of the vulnerable donor tooth. Multiple fitting attempts are usually required to achieve optimal adaptability between the recipient bone and the root surface of the transplanted tooth . Every fitting attempt further increases the risk of trauma to the periodontal ligament and prolongs the extraoral time . In modern autotransplantation techniques, the risk of damage to the donor tooth is minimized by the use of a preoperatively designed surgical template instead of the donor tooth . This replica can be fabricated based on preoperative cone beam computed tomography (CBCT) of the donor tooth. During surgery, the replica functions as a guide, enabling a quick and straightforward autotransplantation procedure .

This systematic review aims to provide an overview of studies involving autotransplantation with the use of a surgical guide for preparation of the neo-alveolus at the recipient site prior to donor tooth extraction. Different autotransplantation techniques are discussed, and the outcomes of this new procedure are assessed.

Methods

This literature review was conducted in accordance with the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) .

Identification of relevant studies

An electronic search of the PubMed, Embase, Web of Science, and Cochrane databases was conducted. Articles published from database inception to 24 March 2016 were retrieved, without any restrictions in terms of year or language of publication ( Appendix 1 ). The reference and citation lists of relevant articles were subsequently scanned manually to identify any additional relevant studies. Duplicates were removed, and all articles were collected in an Endnote database.

Specific inclusion and exclusion criteria were set to identify relevant in vitro studies, case reports, and clinical retrospective/prospective studies. All studies involving autotransplantation with the aid of rapid prototyping for fabrication of individually designed replicas of donor teeth in humans were included. In vitro studies involving fabrication, planning, and surgical aspects of autotransplantation procedures were included. Studies that did not report on individual templates were excluded. Studies that reported on non-individualized or archetypal templates were thus excluded.

Prospective and retrospective randomized controlled trials, case–control studies, observational studies, case series, and case reports were all included in this review. Case reports and clinical studies were included only if the article described autotransplantation with the use of rapid prototyping techniques for fabrication of individual replicas of donor teeth in humans. There were no restrictions on the outcome parameters. However, the neo-alveolus at the recipient site had to have been prepared with the aid of an individual three-dimensional (3D) model of the donor tooth. Studies that used conventional autotransplantation techniques (i.e., preparation of neo-alveolus with the donor tooth itself as a guide) were excluded.

Data retrieval

The titles and abstracts of all identified reports were screened independently by two investigators (JV and FJ). If eligibility could not be determined on the basis of the title or abstract, the full text of the article was retrieved. In cases where eligibility of an article could not be determined in consensus, a third investigator (RM) was consulted.

Data were collected using predefined data retrieval forms and included information regarding the study design, participant characteristics, intervention, comparisons, and outcomes. The primary outcome of interest in this literature review was success after autotransplantation with the aid of a donor tooth replica. The advantages and disadvantages of 3D techniques for autotransplantation were also analyzed. Outcomes of in vitro studies included the accuracies of fabrication of the replica and planning/placement of the donor tooth.

Outcomes of case reports and clinical studies included success and survival rates, ankylosis, root resorption, clinical and/or radiographic abnormalities, healing stage, number of fitting attempts, and extra-alveolar time of the donor tooth.

Quality evaluation and risk of bias

The Checklist for Reporting In vitro Studies (CRIS guidelines) was used for the assessment of quality of in vitro studies . The checklist recorded whether the in vitro study reported a sample size calculation, meaningful intergroup differences, sample preparation and handling, allocation sequence, randomization, blinding, and statistical analysis.

For case reports, the CAse REport (CARE) checklist was used for the assessment of compliance with the guidelines . The criteria assessed by the CARE checklist were: inclusion of the words ‘case report’ in the title, two to five key words, abstract; introduction; patient information; clinical findings; timeline; diagnostic assessment; therapeutic intervention; follow-up; outcomes; discussion; patient perspective; and informed consent.

Non-randomized clinical studies were assessed using the methodological index for non-randomized studies (MINORS) . This checklist recorded whether the clinical studies reported the aims of the study, methodology for inclusion, follow-up, data collection, evaluation of endpoints, and sample size including subjects lost to follow-up. For comparative studies, the equivalence of the included groups and methods of statistical analysis were also evaluated. The assessment tool prescribed by the Cochrane Handbook for Systematic Reviews of Interventions was used to further assess the potential risk of bias of clinical studies in the following domains: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting, and other sources of bias . Studies that satisfied all of these criteria were classified as having a low risk of bias, while those that did not meet one of the criteria were classified as having a moderate risk of bias; studies that did not meet two or more criteria were classified as presenting a high risk of bias.

Outcome measures and data synthesis

The findings were collated, and three tables presenting the summary of findings based on the study type—in vitro studies, case reports, and clinical studies—were constructed. In vitro studies were subdivided according to the reported accuracies of the printing and planning processes. The results of case reports were pooled in terms of success and survival, while those of clinical studies were pooled in terms of success, survival, and extraoral time of the donor tooth.

Statistical analysis

No statistical meta-analysis was performed in this review.

Results

Literature search and identification of relevant studies

The search strategies outlined above yielded 370 articles, of which 247 were retained after elimination of duplicates. Upon screening of the titles and abstracts, 34 eligible articles were identified, and their full texts were further evaluated for eligibility. Fourteen of the 34 articles did not meet the inclusion criteria and one article was found to be a clinical update of a previous study. These 15 articles were excluded. Thus, 19 studies were finally included in this review. Since one of the articles described both in vitro and clinical results, the final dataset included five in vitro studies, nine case reports, and six clinical studies. No randomized controlled trials or systematic reviews were identified in the search. A flowchart of the selection and inclusion process is presented in Fig. 1 .

Fig. 1
Flowchart of the literature review process.

Quality evaluation and risk of bias

Assessment of the five in vitro studies according to the CRIS guidelines revealed their quality of evidence to be low . Although all five studies presented a detailed explanation of sample preparation and handling, none included information regarding calculation of the sample size and allocation sequence.

None of the case reports satisfied all of the criteria of the CARE checklist, and, consequently, their quality of evidence was also determined to be low . The sample size of the included case reports ( n = 1) evidently resulted in a poor quality of evidence.

The clinical studies were all descriptive in nature, except for one case–control study. According to the MINORS checklist, the five descriptive studies scored 9–14 points out of a possible 16 points (MINORS score), while the case–control study scored 19 out of a possible 24 points . According to the Cochrane tool, the risk of bias of all six clinical studies was high .

Appendix 2 presents the checklist scores of the individual studies. Appendix 3 presents the risk of bias of the clinical studies according to the Cochrane tool.

In vitro studies

The characteristics and outcomes of the five in vitro studies included in the present review are presented in Table 1 . The sample size of these studies ranged from 1 to 50 transplanted teeth. Three studies investigated the accuracy of fabrication of donor tooth replicas in terms of agreement in structure between the replica and donor tooth. One study investigated the accuracy of 3D planning in terms of agreement between planning and placement of the transplant. Another study assessed the accuracies of both the fabrication process of the replica and the planning process of autotransplantation.

Table 1
Characteristics and outcomes of in vitro studies.
Study Year Study size ( n ) Results
Fabrication accuracy
Shahbazian et al. 2010 1 premolar with closed apex Linear measurements: agreement between −0.25 mm and +0.25 mm in 79%, overestimation in 3%, and underestimation in 18% of cases
Lee and Kim 2012 12 random teeth Replicas were on an average 0.067 mm smaller in size than 3D CT images of teeth, which were on an average 0.149 mm smaller in size than real teeth
Lee et al. 2015 50 molars with closed apices Volumetric measurements: fused deposition modelling, −1.48%; PolyJet, +0.71%; both techniques produced clinically acceptable replicas
Khalil et al. 2016 6 random teeth with closed apices Dimensional differences between real teeth and replicas were below the clinically required accuracy level of 250 μm for all 3D printing technologies
Placement accuracy
Shahbazian et al. 2010 1 premolar with closed apex No reshaping of the neo-alveolus after preparation with the aid of a stereolithographic surgical guide; immediate good fit without the need for manipulation of donor tooth
Anssari Moin et al. 2016 1 canine with closed apex Angular deflection from the planned position was 3.1°; comparison of bodily 3D positions revealed a deviation of 0.89 mm
3D, three-dimensional; CT, computed tomography.

With regard to the accuracy of the rapid prototyping process, Shahbazian et al. reported that the replica was accurate to within 0.25 mm of the native tooth. They concluded that this finding indicated the feasibility of application of stereolithographic models for in vivo planning of CBCT-based autotransplantation. Lee and Kim found that 3D CT images of teeth were on an average 0.149 mm smaller in size than real teeth, while donor tooth replicas were on an average 0.067 mm smaller in size than CT images of the teeth. Lee et al. comparatively evaluated the accuracy of printing of two different technologies—fused deposition modelling (FDM) and PolyJet. While the FDM replicas were slightly smaller than the original donor teeth, the PolyJet models were slightly bigger. Although these differences were statistically significant, the authors regarded them as clinically insignificant. Khalil et al. evaluated the accuracies of three different 3D printing technologies—stereolithography apparatus (SLA), FDM, and PolyJet—and found that the dimensional differences of these technologies with the original tooth were well below the clinically required surgical accuracy level of 0.25 mm. They therefore concluded that reliable replicas could be produced with any of these three techniques.

The accuracy of transplantation planning with the aid of a surgical drilling guide and donor tooth replica was evaluated in two studies. In the study by Anssari Moin et al. , assessment of the accuracy of autotransplantation with computer-guided templates and custom-designed surgical tools revealed cervical and apical deviations of 1.25 and 0.89 mm, respectively. The angular deflection of the transplanted tooth relative to the planned position of the donor tooth was 3.1°. Shahbazian et al. concluded that stereolithographic surgical guidance enables a more efficient and predictable approach towards autotransplantation.

Case reports

The characteristics and outcomes of the case reports are presented in Table 2 . While eight studies reported on single tooth transplantation, one study reported on autotransplantation of two teeth within the same patient.

Table 2
Characteristics and outcomes of case reports.
Study Year Study size ( n ) Success Survival Extraoral time Follow-up time (months)
Harzer et al. 2009 1 premolar with open apex Successful regeneration of periodontal ligament Yes Immediate 20
Honda et al. 2010 1 mandibular third molar with closed apex Postoperative endodontic treatment, as planned; no signs of pathology Yes NR 48
Keightley et al. 2010 1 premolar with open apex No signs of pathology; continued root formation; the tooth was clinically normal Yes < 1 min 6
Pang et al. 2011 1 premolar with open apex No abnormalities in mobility or percussion; no periodontal disease or root resorption Yes 30 s 24
Park et al. 2013 1 premolar with closed apex Radiographic evaluation, periodontal probing, and visual inspection met the success criteria Yes 3 min 36
Lee et al. 2014 1 mesiodens with closed apex Normal postoperative appearance without signs of pathology Yes NR 36
Park et al. 2014 2 molars with closed apex Normal mobility and probing depth; visible lamina dura; no root resorption or inflammation Yes NR 10
van der Meer et al. 2016 1 premolar with open apex Transplanted tooth exhibited signs of vitality during pulp testing and continuous root development; pulp obliteration was observed Yes “Minimum” 12
Vandekar et al. 2015 1 impacted central incisor with closed apex Postoperative endodontic treatment as planned; good aesthetics and function Yes NR 16
NR, not reported.

Four case reports described transplantation of donor teeth with open apices, with root formation varying from 50% to 90% . The remaining five case reports described a total of six transplanted teeth with complete root formation; these teeth received endodontic therapy according to the standard autotransplantation protocol . All case reports described the autotransplantation of premolars or molars, except Vandekar et al. who described autotransplantation of a central incisor, and Lee et al. who reported autotransplantation of a mesiodens. The follow-up durations of the studies varied from 6 to 48 months.

The extraoral time of the donor tooth varied from almost nil to 3 min. At the end of follow-up, all 10 transplants had survived and were present as clinically normal teeth without any signs of pathology. None of the teeth required additional surgical procedures.

Clinical studies

The characteristics and outcomes of the six clinical studies included in this review are presented in Table 3 . Five observational studies described sample sizes ranging from 5 to 182 transplanted teeth. One case–control study described 24 teeth transplanted using a guidance technique involving 3D replicas of donor teeth and 24 matched control teeth transplanted using a conventional autotransplantation technique. The clinical studies reported success and survival rates of 3D autotransplantation of 80.0–91.1% and 95.5–100%, respectively.

Table 3
Characteristics and outcomes of clinical studies.
Study Year Study size ( n ) Success Survival Extraoral time Follow-up time (months)
Lee et al. 2001 22 undefined teeth No radiographic signs of root resorption in teeth transplanted with the aid of 3D replicas NR 3 to 17.5 min NR
Kim et al. 2005 163 third molars, 5 second molars, 12 premolars, 1 canine, and 1 impacted incisor 81.9% classified as completely healed 9 transplants were extracted Immediate to 25 min 2–60
Lee and Kim 2012 182 third molars (open and closed apices) Root resorption in 1.6% of cases; other complications not mentioned NR Immediate to 25 min; mean 7 min NR
Jang et al. 2013 5 molars with open apices No ankylosis or root resorption; continued root development 100% survival Immediate to 2 min 24–90
Shahbazian et al. 2013 Treatment cases:
24 premolars
Replacement resorption, 1;
apical infection, 1
100% survival <1 min 12
Control teeth:
24 premolars
Ankylosis, 4; progressive infection-related resorption, 2 91.7% survival 3–10 min
Verweij et al. 2016 5 premolars with open apices NR NR 15–45 s NR
3D, three-dimensional; NR, not reported.

Lee et al. reported that computer-aided rapid prototyping minimized the extraoral time and risk of injury to the donor tooth. In their study, the 1-year survival rate of 22 transplants was 100%. Several instances of narrowing of the periodontal space were observed. Shahbazian et al. described a case–control study showing a significant decrease in extraoral time with 3D transplantation in comparison to the conventional method. The average extra-alveolar time for 3D autotransplanted teeth was <1 min and that for control teeth was 3–10 min. These results are in concordance with the findings of Verweij et al. , who also reported extra-alveolar times of <1 min for five teeth autotransplanted using the 3D procedure. The authors described an immediate good fit of the donor tooth replica in all five cases—i.e., no additional fitting attempts with the donor tooth were required. Jang et al. reported an immediate good fit in four of five autotransplantations, with an extraoral time of 2 min in one of the cases. Lee et al. reported remarkably long extraoral durations in 22 cases (mean time, 7 min), which corresponded with the findings of Lee and Kim . Kim et al. reported a mean extraoral time of 7.6 min, ranging from almost nil to 25 min. The increased extra-alveolar time in this study was the result of transplantation of teeth with complete root development, which received extraoral endodontic treatment intraoperatively.

With regard to the procedural time, Shahbazian et al. reported that, in comparison with conventional techniques, the use of 3D replicas of donor teeth significantly reduced the procedural time. The procedural times for traditional and 3D autotransplantation techniques in their study were 40–90 min and 30–45 min, respectively. Verweij et al. reported procedural times of 20–30 min for 3D autotransplantation.

Unsuccessful outcomes of 3D autotransplantation included root resorption, ankylosis, and clinical/radiographic abnormalities. Of the 24 conventionally transplanted teeth in the study by Shahbazian et al. , four exhibited replacement resorption with ankylosis and two exhibited progressive infection-related resorption. In contrast, of the 24 teeth transplanted using the 3D replica-based technique, only one exhibited resorption. Jang et al. ( n = 5) and Lee et al. ( n = 22) found no radiographic signs of root resorption in teeth transplanted with the aid of 3D replicas. Of the 168 patients who received 3D autotransplantation in the study by Kim et al. , four exhibited root resorption (2.4%) and 18 presented ankylosis (10.7%). Lee and Kim reported root resorption in four of 251 cases (1.6%).

Results

Literature search and identification of relevant studies

The search strategies outlined above yielded 370 articles, of which 247 were retained after elimination of duplicates. Upon screening of the titles and abstracts, 34 eligible articles were identified, and their full texts were further evaluated for eligibility. Fourteen of the 34 articles did not meet the inclusion criteria and one article was found to be a clinical update of a previous study. These 15 articles were excluded. Thus, 19 studies were finally included in this review. Since one of the articles described both in vitro and clinical results, the final dataset included five in vitro studies, nine case reports, and six clinical studies. No randomized controlled trials or systematic reviews were identified in the search. A flowchart of the selection and inclusion process is presented in Fig. 1 .

Fig. 1
Flowchart of the literature review process.

Quality evaluation and risk of bias

Assessment of the five in vitro studies according to the CRIS guidelines revealed their quality of evidence to be low . Although all five studies presented a detailed explanation of sample preparation and handling, none included information regarding calculation of the sample size and allocation sequence.

None of the case reports satisfied all of the criteria of the CARE checklist, and, consequently, their quality of evidence was also determined to be low . The sample size of the included case reports ( n = 1) evidently resulted in a poor quality of evidence.

The clinical studies were all descriptive in nature, except for one case–control study. According to the MINORS checklist, the five descriptive studies scored 9–14 points out of a possible 16 points (MINORS score), while the case–control study scored 19 out of a possible 24 points . According to the Cochrane tool, the risk of bias of all six clinical studies was high .

Appendix 2 presents the checklist scores of the individual studies. Appendix 3 presents the risk of bias of the clinical studies according to the Cochrane tool.

In vitro studies

The characteristics and outcomes of the five in vitro studies included in the present review are presented in Table 1 . The sample size of these studies ranged from 1 to 50 transplanted teeth. Three studies investigated the accuracy of fabrication of donor tooth replicas in terms of agreement in structure between the replica and donor tooth. One study investigated the accuracy of 3D planning in terms of agreement between planning and placement of the transplant. Another study assessed the accuracies of both the fabrication process of the replica and the planning process of autotransplantation.

Dec 14, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Autotransplantation of teeth using computer-aided rapid prototyping of a three-dimensional replica of the donor tooth: a systematic literature review
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