Human dentin materials for minimally invasive bone regeneration: Animal studies and clinical cases.

OBJECTIVES: Bone, platelet concentrate, and tooth-derived dentin/cementum have been used as autologous materials in regenerative medicine Dentin materials were first recycled in 2002 for bone regeneration in humans, although bone autografts were noted in the 19th century, and auto-platelet concentrates were developed in 1998. Dentin/cementum-based material therapy has been applied as an innovative technique for minimally invasive bone surgery, while bone autografts are associated with donor site morbidity. METHODS: In October 2021, PubMed, Google Scholar, Scopus, and the Cochrane Library databases from 1980 to 2020 were screened. RESULTS: The demineralized dentin/cementum matrix (DDM) had better performance in bone induction and bone regeneration than mineralized dentin. CONCLUSIONS: Unlike cell culture therapy, DDM is a matrix-based therapy that includes growth factors. A matrix-based system is a realistic and acceptable treatment, even in developing countries. The aim of this review was to summarize the evidence related to both animal studies and human clinical cases using human dentin materials with a patch of cementum, especially DDM.

Potential of Treated Dentin Matrix Xenograft for Dentin-Pulp Tissue Engineering.

INTRODUCTION: This study aims to develop and characterize the regenerative potential of an atelopeptidized treated dentin matrix xenograft using in vitro and in vivo models. METHODS: Freshly extracted bovine dentin was pulverized into 250- to 500-µm particles and demineralized with 17% EDTA for 1, 7, and 13 days. The samples were atelopeptidized with pepsin. The degree of demineralization and the effect of atelopeptidization were assessed using field emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy, respectively. The expression of dentin matrix acidic phosphoprotein 1, dentin sialophosphoprotein, and osteopontin was evaluated in dental pulp stem cells using quantitative real-time polymerase chain reaction. The samples were then implanted intramuscularly in rats for 30 days, and the inflammatory cells were quantified histologically. RESULTS: Field emission scanning electron microscopy combined with energy-dispersive X-ray spectroscopy revealed an exposed tubular structure of dentin after 1 and 7 days of demineralization. Fourier transform infrared spectroscopy confirmed the absence of amide peaks at 1260 to 1640/cm after atelopeptidization. The dental pulp stem cell expression of dentin matrix acidic phosphoprotein 1 and dentin sialophosphoprotein increased in all compared with the untreated control group (P < .05). The maximum expression rates were observed for the 1-day demineralized and atelopeptidized group. The 1-day demineralized group elicited the highest inflammatory response compared with the 7- or 13-day demineralized groups (P < .001). Atelopeptidization significantly decreased the inflammatory response only in the 1-day demineralized dentin group (P < .05). CONCLUSIONS: Atelopeptidization of 1-day demineralized dentin xenograft preserved the collagen structure, minimized the immune reaction, and provided sufficient regenerative potential.

TREATMENT OF UNICAMERAL BONE CYSTS IN CHILDREN: A COMPARATIVE STUDY.

Unicameral bone cysts (UBC) are benign bone tumor-like lesions. Mostly they are located in the metaphyseal-diaphyseal region of long bones in children and adolescents. The etiology of UBC is still unclear. There is no consensus about the protocol of UBC treatment. The aim of this study was to evaluate the effectiveness of three different techniques for the treatment of UBC. This study included 129 pediatric patients with UBC treated at University Children's Hospital in Belgrade during the 8-year period. The mean follow up was 7.14 years. The following parameters were observed: gender, age, site, length of cyst, cyst index, cortical thickness, presentation of pathologic fracture, healing of cyst, treatment complications and length of hospitalization. These parameters were correlated to three treatment modalities, i.e. intracystic methylprednisolone acetate injection (group 1), curettage with bone grafting (group 2) and osteoinductive procedure using demineralized bone matrix (group 3). We found statistically significant differences in healing of the cysts and length of hospital treatment between groups 1 and 2, and between groups 2 and 3. In conclusion, complete healing of UBC can be achieved only using open surgery procedure. Intracystic methylprednisolone acetate instillation can be considered a good option for initial treatment of UBC.

Clinical application of autogenous demineralized dentin matrix loaded with recombinant human bone morphogenetic-2 for socket preservation: A case series.

BACKGROUND: Demineralized dentin matrix (DDM) has potential application as a carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2) in bone regeneration. PURPOSE: To evaluate the efficacy of DDM loaded with rhBMP-2 for socket preservation. MATERIALS AND METHODS: DDM loaded with rhBMP-2 (DDM/rhBMP-2) was applied to 10 experimental sites and DDM alone to 6 control sites. The changes in height and width of the extraction socket after preservation were measured by cone beam computed tomography. Trephine cores were harvested for histomorphometric evaluation before placement of the implant. RESULTS: The reductions in height and width of the socket were more significant in the group treated with DDM than in the group treated with DDM/rhBMP-2. The amount of new bone formation was 34.39% with DDM/rhBMP-2 and 29.75% with DDM; the respective amounts of residual dentin were 8.35% and 16.15%. Although the differences were not statistically significant, the dimensional changes, amount of bone formation, and replacement of DDM in DDM/rhBMP-2 with bone were superior to those of DDM alone. CONCLUSIONS: Within the limitations of this study, we suggest that DDM may be a potential carrier for rhBMP-2 and that it may be possible to reduce the rhBMP-2 concentration to 0.2 mg/mL.

Use of autologous tooth-derived graft material in the post-extraction dental socket. Pilot study.

BACKGROUND: The objectives of the present pilot study are to compare via CBCT the alveolar contraction suffered both vertically and horizontally between the control group and the group using autologous dental material (ADM), as well as to study the densitometric differences between both post-extraction sockets. MATERIAL AND METHODS: A split-mouth study was performed in n = 9 patients who required two extraction of single-rooted teeth deemed suitable for deferred rehabilitation with osseointegrated implants. Two groups were formed - a control group, in which the post-extraction socket was not filled, and an ADM group, in which the alveolar defect was filled with freshly processed autogenous dental material. Both dimensional and densitometric analyses of the alveoli were performed in both groups immediately after surgery (baseline), as well as 8 weeks and 16 weeks later. RESULTS: The mean height of alveolar bone loss was: VL (Control 1.77 mm, loss of 16.87% of initial alveolar height; ADM 0.42 mm, loss of 4.2% of initial alveolar height), HL-BCB (Control 2.22 mm, ADM 0.16 mm, p= 0.067 at 16 weeks). The mean bone loss of the vestibular width (VL-BCB) was much higher in the control group (1.91 mm at 1 mm, 1.3 mm at 3 mm, and 0.89 mm at 5 mm) than in the ADM group (0.46 mm at 1 mm, 0.21 mm at 3 mm, 0.01 at 5 mm, p=0.098 at 16 weeks). At 16 weeks, densitometric analysis of the coronal alveolar area revealed a bone density of 564.35 ± 288.73 HU in the control group and 922.68 ± 250.82 HU in the ADM group (p=0.045 ). CONCLUSIONS: In light of these preliminary results, autologous dentine may be considered a promising material for use in socket preservation techniques.

Three-dimensional ultrastructural analysis of the interface between an implanted demineralised dentin matrix and the surrounding newly formed bone.

Previous investigators have reported that transplanted demineralised dentin matrix (DDM) influences bone formation in vivo. However, the specific mechanism of how dentinal tubules contribute to bone formation has not been determined with regard to DDM transplantation therapy. In this study, we ultrastructurally investigated how DDM contacted the surrounding newly formed bone using a scanning electron microscopy (SEM) three-dimensional reconstruction method that is based on focused ion beam slicing and SEM (FIB/SEM). A pulverised and processed DDM derived from human teeth was implanted into rat calvarial bone defects, and a series of X-ray computed tomographic images were obtained over 12 weeks. Implants with surrounding new bone were removed and histologically examined using FIB/SEM. After obtaining objective block-face images, the target boundary face was reconstructed three-dimensionally. The osteocytes of the new bone tissue surrounding the DDM formed a network connected by their cellular processes and formed bone tissue. It is also interesting that the cellular processes of the osteocytes extended into the dentinal tubules, and that bone tissue with canaliculi had formed and filled the DDM surface.

Bone marrow mesenchymal stem cells combine with Treated dentin matrix to build biological root.

Treated dentin matrix (TDM) as a kind of scaffolding material has been proved odontogenic induction ability on dental-derived stem cells. Given the limited resources of dental stem cells, it is necessary to seek new seed cell which easily obtained. Jaw bone marrow mesenchymal stem cell (JBMMSC) as non-dental-derived stem cell relates to the development of teeth and jaws which suggest us JBMMSCs could act as a new seed cell for tooth tissue engineering. To assess the odontogenic and osteogenic potential of JBMMSCs, cells were induced by TDM extraction in vitro and combined with TDM in vivo. Results were analyzed by PCR, Western Blotting and histology. PCR and Western Blotting showed odontogenic and osteogenic makers were significantly enhanced in varying degrees after induced by TDM extraction in vitro. In vivo, JBMMSCs expressed both odontogenic and osteogenic-related protein, and the latter showed stronger positive expression. Furthermore, histological examination of the harvested grafts was observed the formation of bone-like tissue. Therefore, osteogenic differentiation ability of JBMMSCs were enhanced significantly after being inducted by TDM which illustrates that non-odontogenic derived stem cells are still promising seed cells in tooth root tissue engineering.

Human tooth-derived biomaterial as a graft substitute for hard tissue regeneration.

AIM: The present study was conducted to evaluate the efficacy of human dentine grafts for new bone augmentation. MATERIALS & METHODS: Dentine grafts (demineralized dentine matrix [DDM] and mineralized dentine matrix [MDM]) were prepared and implanted in rats. Tetracycline was administered twice. Paraffin and resin sections were prepared from the harvested grafts and stained respectively with hematoxylin and eosin (in addition to tartrate acid phosphatase for osteoclasts) and Villanueva. The new bone formation (bone thickness, mineral apposition rate and the bone formation rate) was analyzed in tetracycline-labeled resin sections. RESULTS & CONCLUSION: DDM grafts implanted in bone were better able to augment the bone compared to MDM grafts. However, both MDM and DDM failed to induce new bone in ectopic site, they could be considered as alternative autograft substitutes after protocol optimization.

Evaluation of perforated demineralized dentin scaffold on bone regeneration in critical-size sheep iliac defects.

OBJECTIVES: Regenerating critical-size bone injury is a major problem that continues to inspire the design of new graft materials. Therefore, tissue engineering has become a novel approach for targeting bone regeneration applications. Human teeth are a rich source of stem cells, matrix, trace metal ions, and growth factors. A vital tooth-derived demineralized dentin matrix is acid-insoluble and composed of cross-linked collagen with growth factors. In this study, we recycled human non-functional tooth into a unique geometric dentin scaffold, entitled perforated root-demineralized dentin matrix (PR-DDM). The aim of this study was to evaluate the feasibility of PR-DDM as the scaffold for regenerating bone in critical-size iliac defects. MATERIAL AND METHODS: Artificial macro-pores (1 mm in diameter) were added to human vital wisdom tooth after removing the enamel and pulp portions. The modified tooth was demineralized in 0.34 N HNO3 for 30 min and is referred to as PR-DDM scaffold. Critical-size defect (10 mm × 15 mm × 9 mm Ø) was created in the iliac crest of six adult sheep. The in vivo bone regeneration by the scaffold was evaluated by micro-CT, 3D micro-CT, and histological examination at 2 and 4 months post-implantation. RESULTS: PR-DDM exhibited better bone ingrowth, especially in the artificial macro-pores. The results of micro-CT and 3D micro-CT revealed good union between scaffold and native bone. New bone formation was observed in almost all portions of PR-DDM. Higher bone volume inside the scaffold was detected at 4 months compared with 2 months. New bone ingrowth was ankylosed with PR-DDM, and both osteoinduction and osteoconduction capability of PR-DDM were confirmed histologically. The ratio of new bone formation was higher at 4 months compared with 2 months by histomorphometric analysis. CONCLUSIONS: Altogether, these results demonstrated that the human tooth-derived graft material with a unique geometric structure, PR-DDM, contributed to active bone ingrowth in critical-size bone defects. This novel scaffold may have great utility in the near-future clinical application.

Autogenous demineralized dentin matrix from extracted tooth for the augmentation of alveolar bone defect: a prospective randomized clinical trial in comparison with anorganic bovine bone.

OBJECTIVES: The aim of this study was to prospectively evaluate the clinical efficacy and histological outcome of the autogenous tooth graft material (AutoBT) compared to that of anorganic bovine bone (Bio-Oss® , Geistlich, Switzerland) in post-extraction alveolar bone augmentation. PATIENTS AND METHODS: A total of 33 graft sites in 24 patients were included in this study. AutoBT was used in 21 sites of 15 patients and Bio-Oss® was used in 12 sites of 9 patients for alveolar bone augmentation 2-4 weeks after dental extraction. Vertical dimension of grafted bone was measured both at the time of graft placement and at implant fixture placement after 6 months. Trephine cores were harvested for the histomorphometric evaluations during implant placement when feasible. The primary stability of implant fixture was also measured. RESULTS: Infection of graft material or graft bed was not observed and graft sites healed without any notable complications in both groups. The vertical dimensions of alveolar bone increased by 5.38 ± 2.65 mm in AutoBT group and 6.56 ± 3.54 mm in Bio-Oss® group at 6 months post-extraction. Histomorphometrically, new bone formation of AutoBT-grafted site was 31.24 ± 13.87% while that of Bio-Oss® was 35.00 ± 19.33%. The implant stability quotient (ISQ) of implants placed in AutoBT-grafted sites measured 72.80 ± 10.81 while those placed in Bio-Oss® -grafted sites measured 70.0 ± 12.86. There were no statistically significant differences between measurements of the two groups. CONCLUSION: Autogenous demineralized dentin matrix from extracted tooth grafted to extraction sockets for the augmentation of vertical dimension was as effective as augmentation using anorganic bovine bone. Both groups showed favorable wound healing, similar amount of implant stability, and histologically confirmed new bone formation. Thus, the results of this study suggest that autogenous tooth graft material is a viable option for alveolar bone augmentation following dental extraction.

Liquid nitrogen-treated autogenous dentin as bone substitute: an experimental study in a rabbit model.

PURPOSE: Different forms of dentin, including untreated, undemineralized, demineralized, boiled, or mixed with other materials, have been evaluated for efficacy as bone substitutes. However, the effects of application of liquid nitrogen-treated dentin for bone grafting remain unknown. The objective of this study was to chronologically evaluate bone healing following grafting with liquid nitrogen-treated dentin in a rabbit model. MATERIALS AND METHODS: Autogenous dentin treated with liquid nitrogen at -196°C for 20 minutes was used. In 16 New Zealand White rabbits, a bone defect (5 mm in diameter) was created in each femur and randomly grafted with either autogenous dentin (experimental group) or autogenous bone grafts (positive control). In another four rabbits (negative control), a similar defect in each femur was left empty. The rabbits were sacrificed at 2, 4, 8, and 12 weeks. Explants of grafted sites were harvested for histologic and histomorphometric analysis. RESULTS: At 2 and 4 weeks in both the experimental and positive control groups, accelerated formation of new bone was observed, which was undergoing remodeling at 8 and 12 weeks. The mean new bone score was higher in the experimental than in the negative control groups, but this was not statistically significant. CONCLUSION: The present results demonstrated that liquid nitrogen-treated autogenous dentin has both osteoconductive and osteoinductive properties and therefore has potential as a bone substitute.

Host tissue reactions of non-demineralized autogenic and xenogenic dentin blocks implanted in a non-osteogenic environment. An experimental study in rabbits.

Dentoalveolar ankylosis with osseous replacement is often seen after replantation of avulsed teeth, and this process may be used for preservation of alveolar crests after trauma. Its exact mechanisms with regard to osteoinductive properties are not yet fully understood and need to be systematically investigated. Dentin can possibly act as a slow-releasing carrier of bone morphogenic proteins (BMP), and this property of dentin has been proposed to be used as an alternative or supplement to bone grafting in the maxillofacial region. We aimed to initially asses host tissue reactions to dentin by implanting dentin blocks of autogenic and xenogenic human origin in rabbit connective tissue of the abdominal wall and femoral muscle. Animals were sacrificed after a period of 3 months, and histological processing, sectioning and examinations were carried out. Bone formation, cell counts and thickness of capsule surrounding the grafts were evaluated. Only minor signs of heterotopic bone formation were seen. There were no significant differences between autografts and xenografts or grafts implanted in connective tissue or muscle with regards to tissue reactions except for a significant difference (P = 0.018) in findings of more local inflammatory cells in relation to grafts placed in connective tissue in the autograft group. We conclude that during the time frame of this study, non-demineralized dentin, whether autogenous or xenogenic did not have the potential to induce bone formation when implanted in non-osteogenic areas such as the abdominal wall and abdominal muscle of rabbits.

An approach to biomimetics: the natural CAD/CAM restoration: a clinical report.

Those in the dental field have always pursued the perfect dental material for the treatment of compromised teeth. Gold, amalgam, composite resin, glass ionomer, and porcelain have been used. Tooth-like restorative materials (composite resin and porcelain) combined with an effective hard tissue bond have met the growing demand for esthetic or metal-free restorations in the past 15 to 20 years. However, none of those materials can fully mimic the unique properties of dentin (compliance and crack-stopping behavior) and enamel (wear resistance, function). The aim of this article is to report the restoration of an extensively damaged tooth with a natural restoration obtained by milling an extracted third molar tooth with a computer-aided design and computer-aided manufacturing (CAD/CAM) system. The main benefit of this novel technique is the replacement of lost tissues by actual enamel and dentin, with the potential to recover mechanical, esthetic, and biologic properties. The indication for extracting third molars and premolars because of impaction or for orthodontic reasons makes these posterior teeth readily available. The innovation of the method presented here is the optimal use of the extracted tooth substrate thanks to its positioning technique in the CAD/CAM milling chamber.

New bone formation around xenogenic dentin grafts to rabbit tibia marrow.

PURPOSE: From traumatology, it is well known that dentoalveolar ankylosis results in osseous replacement and formation of new bone. This principle is used after decoronation for preservation of the height and width of the alveolar bone crest after trauma. Dentin possesses bone-forming properties and may possibly also be used as a bone augmentation material prior to implant placement. The aim of this study was to investigate whether xenogenic dentin particles inserted into the marrow space of rabbit tibia, a space where there is no solid bone tissue initially, would contribute to new bone formation. MATERIALS AND METHODS: Dentin chips from human teeth were inserted into tibias of ten New Zealand rabbits. The tibial bones were processed for histology after 6 months, and new bone formation was quantified. RESULTS: Bone formation was ranging from 0 to 86% on the dentin fragments, and there was minor inflammation. Bone formation was seen to a larger extent on dentin grafts located close to the native tibial bone wall. There was a significant correlation (r = -0.579, P < 0.001) between the amount of bone formation around the dentin graft and distance to the tibial cortical wall. CONCLUSION: Dentin promotes new bone formation when located close to native cortical bone and may have a potential as a bone augmentation material.

Dentin as a suitable bone substitute comparable to ß-TCP--an experimental study in mice.

Microvascular supply is of fundamental importance to the survival and integration of grafting. Since the autogenous bone is still the gold standard for osseous augmentation, the aim of this study was to analyze the initial osseous, angiogenic and inflammatory response and subsequent osseointegration after implantation of dentin and beta-tricalcium phosphate (ß-TCP) scaffolds into the calvaria chamber of balb/c mice comparing with bone. The vascularisation of perforated implants of dentin (n=8), ß-TCP (n=8) and isogenic calvarial bone (n=8) displaying pores similar in size and structure was analyzed in vivo using intravital fluorescence microscopy. In additional animals (n=24) the osseointegration of dentin, ß-TCP and bone implants was assessed by fluorochrome sequential labelling of growing bone for up to 12 weeks. Animals without implants served as controls. Intravital fluorescence microscopy revealed that implantation of bone substitutes caused an only mild inflammatory response. Comparable to isogenic bone both dentin and ß-TCP scaffolds were found nearly completely vascularized by day 22 and osseointegrated within 12 weeks. In conclusion, dentin and ß-TCP scaffolds are similar to isogenic bone in terms of inflammatory and neovascularization response, highlighting their potential utility in regeneration of bone defects.