Success and survival of autotransplanted premolars and molars during short-term clinical follow-up.

AIM: Autotransplantation is an elegant therapy for single tooth replacement that is too often overlooked in patients with missing teeth. Especially, autotransplantation of third molars to replace heavily damaged or missing molars is often not considered. This study investigated the success and survival of autotransplanted premolars and molars during clinical follow-up. MATERIALS AND METHODS: The medical files and radiographs of 97 consecutive patients were retrospectively investigated. Seventy-nine patients could be included in this study. Autotransplantation of 97 premolars and 14 molars (111 procedures) was performed. The median follow-up time was equal to 13.4 months. RESULTS: In this study group, 82.0% of transplanted teeth were classified as successful and 98.2% were present at the end of follow-up. No transplants were extracted during standard follow-up of 1 year. The 5-year tooth survival probability was 87.5% (95%CI 64.5-100). One premolar and one molar were extracted, respectively, 4 and 9 years after autotransplantation. CONCLUSIONS: These results show that autotransplantation is associated with high success and survival rates and can provide a reliable treatment option for tooth replacement in young patients. Further research regarding long-term outcome is necessary to assess if the transplanted teeth function as normal teeth after clinical follow-up.

Similar in vitro effects and pulp regeneration in ectopic tooth transplantation by basic fibroblast growth factor and granulocyte-colony stimulating factor.

OBJECTIVES: Granulocyte-colony stimulating factor (G-CSF) has been shown to have combinatorial trophic effects with dental pulp stem cells for pulp regeneration. The aim of this investigation is to examine the effects of basic fibroblast growth factor (bFGF) in vitro and in vivo compared with those of G-CSF and to assess the potential utility of bFGF as an alternative to G-CSF for pulp regeneration. MATERIALS AND METHODS: Five different types of cells were examined in the in vitro effects of bFGF on cell migration, proliferation, anti-apoptosis, neurite outgrowth, angiogenesis, and odontogenesis compared with those of G-CSF. The in vivo regenerative potential of pulp tissue including vasculogenesis and odontoblastic differentiation was also compared using an ectopic tooth transplantation model. RESULTS: Basic fibroblast growth factor was similar to G-CSF in high migration, proliferation and anti-apoptotic effects and angiogenic and neurite outgrowth stimulatory activities in vitro. There was no significant difference between bFGF and G-CSF in the regenerative potential in vivo. CONCLUSIONS: The potential utility of bFGF for pulp regeneration is demonstrated as a homing/migration factor similar to the influence of G-CSF.

Allogenic tooth transplantation inhibits the maintenance of dental pulp stem/progenitor cells in mice.

Our recent study suggested that allogenic tooth transplantation may affect the maintenance of dental pulp stem/progenitor cells. This study aims to elucidate the influence of allograft on the maintenance of dental pulp stem/progenitor cells following tooth replantation and allo- or auto-genic tooth transplantation in mice using BrdU chasing, immunohistochemistry for BrdU, nestin and Ki67, in situ hybridization for Dspp, transmission electron microscopy and TUNEL assay. Following extraction of the maxillary first molar in BrdU-labeled animals, the tooth was immediately repositioned in the original socket, or the roots were resected and immediately allo- or auto-grafted into the sublingual region in non-labeled or the same animals. In the control group, two types of BrdU label-retaining cells (LRCs) were distributed throughout the dental pulp: those with dense or those with granular reaction for BrdU. In the replants and autogenic transplants, dense LRCs remained in the center of dental pulp associating with the perivascular environment throughout the experimental period and possessed a proliferative capacity and maintained the differentiation capacity into the odontoblast-like cells or fibroblasts. In contrast, LRCs disappeared in the center of the pulp tissue by postoperative week 4 in the allografts. The disappearance of LRCs was attributed to the extensive apoptosis occurring significantly in LRCs except for the newly-differentiated odontoblast-like cells even in cases without immunological rejection. The results suggest that the host and recipient interaction in the allografts disturbs the maintenance of dense LRCs, presumably stem/progenitor cells, resulting in the disappearance of these cell types.

Enhanced Wnt/ß-catenin signalling during tooth morphogenesis impedes cell differentiation and leads to alterations in the structure and mineralisation of the adult tooth.

BACKGROUND INFORMATION: Previous studies have indicated that over-activation of the wingless interaction site (Wnt)/ß-catenin signalling pathway has important implications for tooth development, at the level of cell differentiation and morphology, as well as for the production of supernumerary teeth. Here, we provide evidence for a crucial role of this signalling pathway during the stage of tooth morphogenesis. We have developed an in vitro model consisting of 14.5-day-old mouse embryo first molars, in which the Wnt pathway is overactivated by the glycogen synthase kinase-3 inhibitor 6-bromoindirubin-3'-oxime (BIO; 20 µM). RESULTS: We found that over-activation of the Wnt/ß-catenin pathway delayed the differentiation and growth of the inner dental epithelium. In addition, in contrast to controls in which Nestin protein expression was restricted to differentiated odontoblasts, in BIO-treated molars, Nestin expression spread through sub-odontoblastic cellular layers. This alteration appears to be related to: (i) the over-expression of Bmp4 in the same region, (ii) the delay in odontoblast precursor cell differentiation and (iii) increased proliferation of mesenchymal cells. Furthermore, treatments longer than 6 days induced the malformation of typical dental structures and led to a total lack of cell differentiation. Finally, over-activation of the Wnt route during odontogenesis resulted in adult teeth which presented altered size, morphology and mineralisation. CONCLUSIONS: Our results indicate that Wnt/ß-catenin over-activation during tooth morphogenesis is sufficient to cause dramatic alterations in the adult tooth, by delaying cellular differentiation and stimulating proliferation of the dental mesenchyme of developing teeth.

An experimental study on periodontal regeneration after subcutaneous transplantation of rat molar with and without cryopreservation: an in vivo study.

This study analysed the effects of cryopreservation on periodontal regeneration of autotransplanted rat molars. First and second maxillary molars (n=92) of 24 four-week-old Wistar rats were gently extracted and autotransplanted into the abdominal tissue immediately (control group n=44) or after cryopreservation in liquid nitrogen for 7 days (experimental group n=48). At 1, 2, 4 and 10 weeks after transplantation, the transplanted molars were excised and regeneration of the periodontal tissues was analysed on histological sections stained with routine H&E and Goldner method. Different tissue responses were scored on a tooth basis: inflammation, regeneration of the periodontal ligament, resorption/apposition of cementum, and alveolar bone formation. Sixty-two teeth were available for histological evaluation, including 30 experimental and 32 control samples. One week after transplantation, both control and test teeth were surrounded by granulation tissue and some areas of root resorption could be seen. After 2 weeks, signs of regeneration of the periodontal ligament, cementum apposition, and new bone formation roughly coincided in both groups, however markedly retarded in the experimental group. After 4 weeks, regeneration progressed equally in both groups, presenting fewer areas of cementum apposition in experimental samples. Finally, 10 weeks after baseline transplantation, no significant differences between both groups could be observed. Cryopreservation followed by autotransplantation of extracted teeth in rats appears to have minimal detrimental effects on regeneration of periodontal tissues after integration periods of 1-10 weeks. However, the present findings indicated that the regeneration process in general is retarded for cryopreserved teeth, as compared to their immediately transplanted homologues.

Application of orthodontic forces prior to autotransplantation - case reports.

AIM: This case report describes the successful autotransplantation of mandibular molars after application of orthodontic forces and discusses the advantages of this technique, that is, pre-application of an orthodontic force for autotransplantation. SUMMARY: After clinical and radiographic examination, autotransplantation was planned with the patient's written informed consent. An orthodontic force was applied, and the surgical procedure was performed after tooth mobility had increased. Root canal treatment was performed within 2 weeks of autotransplantation. At the 1-year follow-up, the transplanted teeth revealed asymptomatic and healthy periodontal conditions. KEY LEARNING POINTS: Autotransplantation is the surgical movement of a tooth from its original location to another site. The pre-application of orthodontic force technique was recently introduced for autogenous tooth transplantation. Pre-application of an orthodontic force may be a useful treatment option for autotransplantation.

Comparison of prognosis of separated and non-separated tooth autotransplantation.

The aim of this study was to compare the prognosis of separated and non-separated tooth autotransplantation of the upper first and second molars with complete root formation undertaken at dental clinics. The participating dentists were requested to provide information on transplantations they had undertaken from 1 January 1990 to 31 December 2010. Data on a total of 708 teeth from 637 patients were collected. This study analysed 35 separated teeth and 22 non-separated teeth of 47 participants ranging from 27 to 76 years of age (mean age: 55·0 years) after data screening and elimination. The cumulative post-transplantation survival rate at 10 years was 77·1% for separated teeth and 63·6% for non-separated teeth as calculated with the Kaplan-Meier method. There were no significant differences between separated teeth and non-separated teeth in a log rank test (P = 0·687). Separated-tooth autotransplantation can help fill narrow recipient sites and increase occlusal supporting zones, but the clinical success rate was only 48·6%. Although transplantation of teeth with complete root formation has limited prognosis, transplantation of upper first and second molars, whether separated or non-separated, is a viable option to replace missing teeth.

Gender difference in tooth autotransplantation with complete root formation: a retrospective survey.

Gender-related risk factors in the survival of transplanted teeth with complete root formation have not yet been identified. The purpose of this study was to investigate gender differences in tooth autotransplantation at dental clinics. We asked participating dentists to provide information on transplantations they had undertaken from 1 January 1990 to 1931 December 2010. The data were screened to exclude patients who underwent more than one transplantation, smokers or those whose smoking habits were unknown, patients under 30 or who were 70 years old and over, cases where the transplanted teeth had incomplete root formation or multiple roots and those with fewer than 20 present teeth post-operation. We analysed 73 teeth of 73 males (mean age, 47.2 years) and 106 teeth of 106 females (mean age, 45.3 years) in this study. The cumulative survival rate and mean survival time were calculated using the Kaplan-Meier method. The cumulative survival rate for males was 88.3% at the 5-year mark, 64.8% at 10 years and 48.6% at 15 years; for females, it was 97.2% at the 5-year mark, 85.9% at 10 years and 85.9% at 15 years. A log-rank test indicated the difference between males and females to be significant (P = 0.011). There was also a significant difference in the main causes for the loss of transplanted teeth: males lost more transplanted teeth due to attachment loss than females (P < 0.05). These results indicate that males require more attention during the autotransplantation process, particularly at the stage of pre-operation evaluation and that of follow-up maintenance.

Importance of root development in autotransplantations: a retrospective study of 137 teeth with a follow-up period varying from 1 week to 14 years.

The aim of the present study was to perform a retrospective study of autotransplanted teeth with a variable but individually maximized follow-up period in order to provide information on the long-term clinical outcome. The sample was obtained from patients who were treated at the University Hospitals KU-Leuven, Belgium, during the period 1996-2010. Of the total of 109 subjects (137 teeth), 98 patients were invited for recall, of whom 68 patients (87 teeth) responded positively. Eleven out of the 109 patients were excluded due to loss of the transplanted tooth. Although 41 patients had no re-examination visit, clinical and radiological data from all 109 subjects were included in the sample. The follow-up period varied from 1 week of 14.8 years, with a mean of 4.9 years. Transplanted teeth receiving orthodontic treatment had a lower risk of ankylosis and were less likely to fail. The risk of root resorption was lower for teeth with stages one-half to three-quarters of root length at the time of transplantation. Molars were more susceptible to ankylosis. Almost all teeth showed partial or full obliteration of the pulp. Absence of further root development was higher in donor teeth with root length stage less than one-half. Trans-alveolar transplantation was less successful. Autotransplantation can be a valid alternative method in young adolescents for replacing missing teeth because of agenesis or trauma. The optimal time to transplant is when the root has reached two-thirds to three-quarters of the final root length.

Esthetic and functional recovery of extensively decayed posterior teeth through conservative treatment.

The case exemplifies the combination of two important principles in dentistry: 1) the maintenance of pulp vitality by the partial excavation of the contaminated dentin followed by the application of a biomaterial; and 2) esthetic and functional recovery based on biological restoration. Tooth vitality was confirmed two months after pulp treatment and restoration was accomplished with a fragment of a tooth extracted from another individual. This method is easy to perform and offers esthetic, functional, emotional and social benefits to the patient.

Tooth autotransplantation: an overview and case study.

It is not uncommon for children or young adults to have congenitally missing teeth or early loss of teeth from trauma or caries. The restorative options are typically bridges, implants, and removable appliances. Often overlooked and misunderstood, another treatment option exists in autotransplantation, where a tooth is moved from one site to another in the same individual. Autotransplantation is well studied and has predictable results comparable to implants, with reported success rates often greater than 90%. This article will provide an overview of autotransplantation plantation, its indications, advantages, complications, and treatment considerations, along with a case of a third molar autotransplant that will serve to highlight these points.

Analysis of the cells isolated from epithelial cell rests of Malassez through single-cell limiting dilution.

The epithelial cell rests of Malassez (ERM) are essential in preventing ankylosis between the alveolar bone and the tooth (dentoalveolar ankylosis). Despite extensive research, the mechanism by which ERM cells suppress ankylosis remains uncertain; perhaps its varied population is to reason. Therefore, in this study, eighteen unique clones of ERM (CRUDE) were isolated using the single-cell limiting dilution and designated as ERM 1-18. qRT-PCR, ELISA, and western blot analyses revealed that ERM-2 and -3 had the highest and lowest amelogenin expression, respectively. Mineralization of human periodontal ligament fibroblasts (HPDLF) was reduced in vitro co-culture with CRUDE ERM, ERM-2, and -3 cells, but recovered when an anti-amelogenin antibody was introduced. Transplanted rat molars grown in ERM-2 cell supernatants produced substantially less bone than those cultured in other cell supernatants; inhibition was rescued when an anti-amelogenin antibody was added to the supernatants. Anti-Osterix antibody staining was used to confirm the development of new bones. In addition, next-generation sequencing (NGS) data were analysed to discover genes related to the distinct roles of CRUDE ERM, ERM-2, and ERM-3. According to this study, amelogenin produced by ERM cells helps to prevent dentoalveolar ankylosis and maintain periodontal ligament (PDL) space, depending on their clonal diversity.

Responses of BrdU label-retaining dental pulp cells to allogenic tooth transplantation into mouse maxilla.

Recently, we demonstrated that a pulse of BrdU given to prenatal animals reveals the existence of slow-cycling long-term label-retaining cells (LRCs), putative adult stem or progenitor cells, which reside in the dental pulp. This study aims to clarify responses of LRCs to allogenic tooth transplantation into mouse maxilla using prenatal BrdU-labeling, in situ hybridization for osteopontin and periostin, and immunohistochemistry for BrdU, nestin, and osteopontin. The upper-right first molars were allografted in the original socket between BrdU-labeled and non-labeled mice or between GFP transgenic and wild-type mice. Tooth transplantation caused degeneration of the odontoblast layer, resulting in the disappearance of nestin-positive reactions in the dental pulp. On postoperative days 5-7, tertiary dentin formation commenced next to the preexisting dentin where nestin-positive odontoblast-like cells were arranged in the successful cases. In BrdU-labeled transplanted teeth, dense LRCs were maintained in the center of the dental pulp beneath the odontoblast-like cells including LRCs, whereas LRCs disappeared in the area surrounding the bone-like tissue. In contrast, LRCs were not recognized in the pulp chamber of non-labeled transplants through the experimental period. Tooth transplantation using GFP mice demonstrated that the donor cells constituted the dental pulp of the transplant except for endothelial cells and some migrated cells, and the periodontal tissue was replaced by host-derived cells except for epithelial cell rests of Malassez. These results suggest that the maintenance of BrdU label-retaining dental pulp cells play a role in the regeneration of odontoblast-like cells in the process of pulpal healing following tooth transplantation.

Root and periodontal tissue development after allogenic tooth transplantation between rat littermates.

OBJECTIVE: The study was designed to investigate the development of roots and periodontal tissues after allogenic tooth transplantation between rat littermates by micro-computed tomography (micro-CT) and histology. MATERIALS AND METHODS: The upper right second molars in 2-week-old rats were extracted and immediately transplanted into the upper right first molar socket of rat littermates under anesthesia. The upper left second molars in 2-week-old recipient rats were used as a control. The rats were fixed and tissues analyzed at 0, 4, 8, or 12 weeks after transplantation. Root development of seven rats in each group was analyzed quantitatively using micro-CT. Periodontal tissue formation was examined qualitatively by histologic methods. RESULTS: Roots developed after allogenic transplantation, but they were significantly shorter than control roots. The number of roots varied from one to four in transplanted teeth, while it was consistently four in control teeth. Periodontal tissue formation in transplanted teeth was equivalent to that of the control teeth. CONCLUSION: Allogenic transplantation between rat littermates permits root development and periodontal tissue formation.

Stabilization of autotransplanted teeth using thermoplastic retainers.

OBJECTIVE: Different fixation techniques have been used for stabilization of autotransplanted teeth. Because rigid or extended fixation periods can cause complications such as ankylosis and disturbances of pulpal revascularization, our aim was to evaluate an alternative technique, a removable splint, for improving the success rate of autotransplanted molar teeth. STUDY DESIGN: In 44 patients, (20 male and 24 female patients), 45 transplanted teeth were analyzed. These cases were followed for 31 to 47 months after operation. Transplanted teeth were evaluated after use of a thermoplastic retainer for 1 month, in terms of success rate and dissatisfaction with this apparatus. The primary stability, ankylosis, and root resorption were also analyzed. RESULTS: To date, 1 transplant was extracted after 6 months due to unpreventable periapical root inflammation, and 2 transplants were extracted after one year due to external root resorption. Although 2 ankylosed transplants were still functional after an average follow-up period of three years, with no dissatisfaction by the patients, these cases were treated as failures because of the probable risk for external root resorption. The remaining 40 (88.8 % success rate) transplants remained asymptomatic and functioning for a mean follow-up period of 37 months. In the assessment of dissatisfaction with the thermoplastic retainer, 36 (81.8 %) patients had no or little dissatisfaction, 4 (9 %) patients had very appreciable or excessive dissatisfaction, and 4 (9 %) patients had moderate dissatisfaction. CONCLUSIONS: A thermoplastic retainer for use after autotransplantation of third molar teeth is a reasonable and useful method and a good alternative to conventional rigid or semi-rigid splints. This technique was especially useful in autotransplanted teeth that had poor stability, i.e., in cases in which it is conventionally advised to use long-term rigid or semi-rigid splints.

[Dentification ability of inbred strain mice tooth germs homologically transplanted into oral submucosa].

OBJECTIVE: To establish a suitable environment for the bioengineered teeth in vivo by observing the dentification ability of BALB/C mice tooth germs homologically implanted into the oral submucosa. METHODS: The first molar tooth germs of BALB/C mice 4 days after birth were transplanted into the oral submucosa of BALB/C male mice, and then recycled for regular histological observation after 1, 2, 3, and 6 week transplantation. RESULTS: The tooth germs in the oral submucosa grew well with continuing developing enamelum and pulpodentinal complex, and the dentinal tubules were clear. CONCLUSION: The environment of the BALB/C male mice oral submucosa is favorable for the growth of tooth germs in inbred strain BALB/C mice, and it can provide a new environment for the development of bioengineered teeth in vivo.

Long-term outcomes 1-20 years after autotransplantation of teeth: clinical and radiographic evaluation of 66 premolars and 8 molars.

In this retrospective study we investigated the long-term survival of autotransplanted premolars and molars with incompletely developed roots. The presence of the transplanted teeth and their outcome after autotransplantation was ascertained from clinical and radiographic evaluation by a maxillofacial surgeon or dentist. Kaplan Meier survival curves were estimated for the total population and for the two groups (premolars and molars). Fifty-one patients with 74 transplanted teeth were included, and the median duration of follow-up was 10 (range 1-20) years. Four of 66 premolars and one of 8 molars were removed and the cumulative survival was 95.4% (95% CI 90.3 to 100). The difference in survival between the premolars and molars was not significant. These results show that the long-term survival of autotransplanted teeth is good. Replacement of a single tooth by autotransplantation should therefore always be considered and is preferred when a suitable donor tooth is available.

Alveolar bone regeneration of subcutaneously transplanted rat molar.

Regeneration of alveolar bone is essential for periodontal treatment. Recently, cell replacement therapy has been focused on periodontal disease, but the source of the cells that regenerate alveolar bone is still uncertain. Therefore, to clarify the source of these bone-regenerating cells, we transplanted GFP-transgenic rat molars into the subcutaneous tissues of wild-type rats. Five days after transplantation, the tooth was surrounded by connective tissue containing many blood vessels. At 10 days, bone-like tissue was formed in the connective tissue between the branches of the bifurcated root. This hard tissue expanded to almost all of this bifurcation area without osseous ankylosis after 20 days. All osteoblast-like cells in the newly formed matrix were immunopositive for GFP. In addition, these cells and the peripheral cells of the matrix showed intense immunoreactivity for BMP4, Runx2, BSP, and OPN. These results demonstrate that periodontal ligament tissue contains osteoprogenitor cells that have the ability to regenerate alveolar bone. Our model suggests that these regeneration processes might be similar to normal alveolar bone formation.

Capacity of dental pulp differentiation in mouse molars as demonstrated by allogenic tooth transplantation.

Dental pulp elaborates both bone and dentin under pathological conditions such as tooth replantation/transplantation. This study aims to clarify the capability of dental pulp to elaborate bone tissue in addition to dentin by allogenic tooth transplantation using immunohistochemistry and histochemistry. After extraction of the molars of 3-week-old mice, the roots and pulp floor were resected and immediately allografted into the sublingual region in a littermate. In addition, we studied the contribution of donor and host cells to the regenerated pulp tissue using a combination of allogenic tooth transplantation and lacZ transgenic ROSA26 mice. On Days 5-7, tubular dentin formation started next to the preexisting dentin at the pulp horn where nestin-positive odontoblast-like cells were arranged. Until Day 14, bone-like tissue formation occurred in the pulp chamber, where intense tartrate-resistant acid phosphatase-positive cells appeared. Furthermore, allogenic transplantation using ROSA26 mice clearly showed that both donor and host cells differentiated into osteoblast-like cells with the assistance of osteoclast-lineage cells, whereas newly differentiated odontoblasts were exclusively derived from donor cells. These results suggest that the odontoblast and osteoblast lineage cells reside in the dental pulp and that both donor and host cells contribute to bone-like tissue formation in the regenerated pulp tissue.

A new procedure for processing extracted teeth for immediate grafting in post-extraction sockets. An experimental study in American Fox Hound dogs.

OBJECTIVES: To investigate freshly extracted dental particulate used to graft post-extraction sockets in dogs, comparing new bone formation at experimental and control sites. MATERIALS AND METHODS: Bilateral premolars P2, P3, P4 and first mandibular molars were extracted atraumatically from six American Fox Hound dogs. The teeth were ground immediately using a 'Smart Dentin Grinder'. The dentin particulate was sieved to ensure a grain size of 300-1200µm and immersed in an alcohol cleanser to dissolve organic debris and bacteria, followed by washing in sterile saline buffer solution. The animals were divided into two groups randomly: group 'A' (control) samples were left to heal without any extraction socket grafting procedure; group 'B' (experimental) sockets were filled with the autogenous dentin particulate graft. The rate of tissue healing and the quantity of bone formation were evaluated using histological and histomorphometric analyses at 60 and 90 days post-grafting. The type of bone generated was categorized as woven (immature bone) or lamellar bone (mature bone). RESULTS: Substantially more bone formation was found in Group B (experimental) than Group A (control) at 60 and 90 days (p<0.05). Less immature bone was identified in the dentin grafted group (25.7%) than the control group (55.9%) [corrected]. Similar differences were also observed at 90 days post grafting. CONCLUSION: Autogenous dentin particulate grafted immediately after extractions may be considered a useful biomaterial for socket preservation, protecting both buccal and lingual plates, generating large amounts of new woven bone formation after 60 days, and small amounts of lamellar bone after 90 days healing.