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.

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.

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.

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.

Tooth hard tissue stimulates bone remodeling as a potential motive force during tooth eruption.

Tooth eruption is an orientating action which migrates teeth coronally during life, even in bone or after occlusion contact is lost. The eruption pathway is due to bone resorption near the enamel crown and bone deposition around the cementum-covered roots. Due to their proximity to bone resorption and deposition, we hypothesize that the hard tissues enamel, dentine or cementum are important during eruption. In the present study, extracted human teeth were cut into enamel samples, enamel-dentine samples or dentine-cementum samples, and implanted into bone defects in rabbit tibia. Hematoxylin and eosin, tartrate-resistant acid phosphatase activity, tetracycline tracing and scanning electron microscopy were used to investigate bone resorption and deposition 1-8 weeks after surgery. The results showed that resorption lacunae with numerous osteoclasts were observed facing enamel and significant new bone deposition occurred near the cementum surface, compared to other hard tooth surfaces. These findings indicate that the enamel crown may stimulate bone resorption and initiate the eruption pathway, and that the cementum root may stimulate bone deposition. Bone regeneration initiated by tooth hard tissues may be a potential motive force during tooth eruption.

Effect of Tisseel on bone healing with particulate dentin and plaster of Paris mixture.

OBJECTIVES: The purpose of this study was to evaluate the effect of Tisseel on the early healing of bone defects in the skulls of rats. STUDY DESIGN: Forty-eight rats were randomly assigned to 4 groups, and each group was further divided into 3 subgroups which were examined at 4 and 8 weeks after the defects were filled. The 4 different groups were animals containing: no graft (group 1); particulate dentin and plaster of Paris mixture graft (group 2); Tisseel and particulate dentin and plaster of Paris mixture graft (group 3); and Tisseel graft (group 4). After killing the animals at 4 and 8 weeks after surgery, all implant blocks were prepared for histologic sections and histomorphometric analysis. RESULTS: The overall new bone formation was significantly different between the 4-week samples and the 8-week samples. Significant differences between groups 1 and 2, groups 1 and 3, groups 1 and 4, groups 2 and 4, and groups 3 and 4 were observed at 4 weeks after surgery. At 8 weeks after surgery, significant differences between groups 1 and 2, groups 1 and 3, groups 1 and 4, and groups 2 and 4 were observed. As expected, effective bone formation was observed when the defects were filled with either particulate dentin, Tisseel, or particulate dentin-Tisseel combination. It was also observed from this study that particulate dentin is especially effective, followed by the particulate dentin-Tisseel combination and Tisseel. CONCLUSION: It was concluded that the use of Tisseel may be an alternative therapy for regenerating bone in defects when used in combination with particulate dentin.

Standards for modified osteoodontokeratoprosthesis (OOKP) surgery according to Strampelli and Falcinelli: the Rome-Vienna Protocol.

PURPOSE: To establish a time-proven "gold standard" in modified osteoodontokeratoprosthesis (OOKP) surgery. METHODS: The OOKP is the procedure of choice for restoring sight in patients with corneal blindness caused by end-stage ocular surface disease not amenable to penetrating keratoplasty. Members of the OOKP Study Group met in Rome, Italy in 2001 and Vienna, Austria in 2002 to discuss indications and contraindications, patient selection, surgical technique, postoperative care, and recognition and management of complications of OOKP surgery according to Strampelli and modified by Falcinelli. RESULTS: Falcinelli's modification of Strampelli's technique of OOKP surgery remains the gold standard as far as visual and keratoprosthesis-retention results are concerned. The agreement on indications and contraindications, patient selection, surgical technique, postoperative care, and recognition and management of complications of this technique of OOKP surgery is summarized in the text of this manuscript. CONCLUSION: This standard technique of modified OOKP surgery, where adequately performed, is capable of providing excellent anatomic and functional results even in the long term. In patients with corneal blindness untreatable by other approaches, we strongly recommend this technique for visual rehabilitation. Students of OOKP surgery should become familiar with the protocol described in this paper before subjecting the technique to further modifications.

Suppression of osteoclastogenesis in rheumatoid arthritis by induction of apoptosis in activated CD4+ T cells.

OBJECTIVE: To examine the suppressive effect of anti-human Fas monoclonal antibody (mAb) on osteoclastogenesis in rheumatoid arthritis (RA) both in vitro and in vivo. METHODS: For in vitro analysis, activated CD4+ T cells derived from peripheral blood mononuclear cells were left untreated or were treated with humanized anti-human Fas mAb (R-125224) and cocultured with human monocytes. On day 12, the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells was counted. For in vivo analysis, tissue derived from human RA pannus was implanted with a slice of dentin subcutaneously in the backs of SCID mice (SCID-HuRAg-pit model). R-125224 was administered intravenously once a week for 3 weeks. The implanted tissue and dentin slice were removed, and the pits formed on the dentin slice were analyzed. RESULTS: In vitro, coculture of activated CD4+ T cells and peripheral monocytes induced osteoclastogenesis. The number of TRAP-positive multinucleated cells was reduced when activated CD4+ T cells were treated with R-125224. We established a new animal model for monitoring osteoclastogenesis, SCID-HuRAg-pit. We found that with R-125224 treatment, the number of pits formed on the implanted dentin slices was significantly reduced and the number of lymphocytes in the implanted RA synovial tissue was dramatically reduced in this model. CONCLUSION: This is the first study to demonstrate the suppressive effect of anti-human Fas mAb on osteoclastogenesis in RA synovial tissues through the induction of T cell apoptosis. Induction of apoptosis of infiltrated lymphocytes could be a useful therapeutic strategy for RA, in terms of suppressing both inflammation and bone destruction.

Hard tissue formation on dentin surfaces applied with recombinant human bone morphogenetic protein-2 in the connective tissue of the palate.

The purpose of this study was to evaluate whether hard tissue might be formed on dentin surfaces applied with recombinant human bone morphogenetic protein-2 (rhBMP-2) in palatal connective tissue. Fifty-eight dentin blocks were prepared from rat roots, demineralized with 24% EDTA (pH 7.0), applied with 0, 50 and 100 microgram/ml rhBMP-2, and labeled as groups 0, 50 and 100. The dentin blocks were then transplanted into palatal connective tissue of rats, and specimens were prepared at two and four weeks after surgery for histologic and histomorphometric examinations. The results showed that the percentage of newly formed hard tissue in relation to the total dentin block surface length in groups 0, 50 and 100 was 0.0%, 2.8% and 4.4% at two weeks, and 0.0%, 1.6% and 12.8% at four weeks, respectively. New hard tissue formation in groups 50 and 100 was significantly promoted as compared to group 0 (p < 0.01). These findings thus indicate that rhBMP-2 application to dentin enhanced new hard tissue formation on dentin surfaces in the connective tissue of the palate.

Use of particulate dentin-plaster of Paris combination with/without platelet-rich plasma in the treatment of bone defects around implants.

PURPOSE: To evaluate the effect of particulate dentin-plaster of Paris with and without platelet-rich plasma (PRP) on bone healing and new bone formation around titanium dental implants in a canine model. Histologic sections and histomorphometric analysis of the defects were obtained at 6 and 12 weeks after surgery. MATERIALS AND METHODS: Three circular bone defects were surgically prepared in iliac crest sites in each of 10 animals. A total of 30 Avana dental implants were placed in the animals. They were self-tapping, screw-type implants, 10 mm in length and 4 mm in diameter, all made of commercially pure titanium. A titanium implant was placed centrally in each defect. In each dog, the defects were treated with 1 of the following 3 treatment modalities: (1) no treatment (control); (2) grafting with particulate dentin-plaster of Paris; (3) grafting with particulate dentin-plaster of Paris and PRP. RESULTS: Histologic analysis showed that all of the bone defects surrounding the implants that were treated with particulate dentin-plaster of Paris, with and without PRP, were filled with new bone. The defects that were not treated (control) demonstrated new bone formation only in the inferior threaded portion of the implants. DISCUSSION: Histomorphometric results revealed a higher percentage of bone contact with particulate dentin-plaster of Paris and PRP compared to the control and particulate dentin-plaster of Paris. CONCLUSIONS: These results suggested that bone defects around titanium implants can be treated successfully with particulate dentin-plaster of Paris, and that the outcome can be improved if PRP is also used.

Grafting of large defects of the jaws with a particulate dentin-plaster of paris combination.

OBJECTIVE: The purpose of this report is to show the usefulness and discuss the effects of a particulate dentin and plaster of paris combination as a bone graft material in jaw defects. STUDY DESIGN: This was a retrospective evaluation of 10 patients with jaw defects who underwent grafting with a combination of particulate dentin and plaster of paris. The material was used when the defects were more than 20 mm in diameter. The ratio was 2:1 by weight. Patients were examined for any evidence of infection and recurrence during the follow-up periods. RESULTS: During a mean follow-up of 52.2 months (range, 50 to 57 months), patients had minor immediate postoperative complications. These complications were swelling and perforation; they were treated without problems through use of incision and drainage, antibiotic treatment, and buccal flap. CONCLUSIONS: On the basis of the results that we obtained radiographically and clinically, it may be concluded that the particulate dentin plaster mixture is a useful and readily available material for bone substitute.

An experimental study of chondrogenesis and osteogenesis in rat submandibular gland induced by implantation of demineralized dentin.

Demineralized dentin pieces were implanted in 18 rat submandibular glands to examine the chondrogenesis and osteogenesis in pleomorphic adenoma of the salivary gland. After 7 days of implantation, a large amount of cartilage tissue was found next to the inner portions of the implanted pieces, and small amounts of the osteoid and cartilage tissues were detected next to the outer portions. A small amount of bone tissue was found in contact with the cartilage 10 days after the implantation. In the inner portions, invasions of capillaries and a small amount of osteoid tissue were noted. These histological findings resembled those of endochondral ossification. Large amounts of bone tissue and resorption of the implant were observed after 14 days. It has been suggested that cartilage and bone are produced by bone morphogenetic proteins (BMP) in demineralized dentin resulting in chondrogenesis followed by osteogenesis in submandibular gland. Apparently, undifferentiated mesenchymal cells are produced by implantation, undergo dedifferentiation, and are redifferentiated into chondroblasts and osteoblasts in the presence of BMP. These results suggest that chondrogenesis and osteogenesis in the submandibular gland are induced by BMP. It is possible that the chondroid tissues in pleomorphic adenoma of the salivary glands are induced by proteins such as BMP.

Osteogenic potential of nonvital tissues and synthetic implant materials.

Following the application of various techniques to restore or rebuild alveolar bone with different implants, results are generally unpredictable. In successful cases it is not clear whether the materials are capable of initiating osteogenesis by metaplastic induction, where endogenous bone formation had failed, or initiating osteogenesis by stimulating the regeneration of existing vital bone tissue by irritation. In order to discriminate between these two possibilities, 40 Sprague-Dawley descent rats were implanted with both devitalized tissues and synthetic materials in an area where bone is not usually formed: the anterior eye chamber. The test materials consisted of two devitalized tissues: boiled bone marrow and demineralized dentin, and six synthetic materials: formalin 10% and 40%, formic acid 10% and 88%, plaster of Paris, and ceramic tricalcium phosphate (Durapatite). Test materials were inserted into 59 chambers, but bone was not formed in any of these cases following a three-week experimental test period. Following implantation of 21 control chambers with viable mature marrow, bone was formed in 5 of 21 cases (24%), following the three-week test period. These findings appear to indicate that the reported cases where bone regeneration successfully occurred following implantation probably resulted from unpredictable irritational factors upon the existing vital bone tissue rather than by metaplastic induction.

Estudo histomorfológico do tecido conjuntivo subcutâneo do rato ao implante de pastas à base de hidróxido de cálcio, contidas em tubos de dentina humana / Histomorphologic study of the subcutaneous connective tissue reactions of rat, due to the implantation of calcium hydroxide pastes contained in human dentin tubes

Foram utilizados 36 ratos, albinos, machos, adultos jovens, divididos em 3 grupos, de 12 animais cada, agrupados inicialmente em gaiolas para 3 indivíduos. Os animais receberam implantes de tubos de dentina humana contendo as seguintes pastas: Grupo I - Hidróxido de cálcio + Polietileno glicol 400; Grupo II - Hidróxido de cálcio + Lipiodol (ultrafluido) e Grupo III - Hidróxido de cálcio + Paramonoclorofenol canforado 2,5:7,5. Decorridos os períodos de 30, 60, 90 e 120 dias, os animais foram recuperados e as áreas circunjacentes aos implantes, removidas e preparadas para estudo histológico. Os resultados microscópicos mostraram que as misturas correspondentes aos Grupos I, II e III, comportaram-se como irritantes de tecido conjuntivo subcutâneo do rato, possibilitando no entanto cápsula em colagenizaçäo progressiva no decorrer dos períodos

Osteogenic potential of autogenic demineralized dentin implanted in bony defects in dogs.

The bone morphogenetic properties of implants of autogenic demineralized dentin were evaluated. The dentin matrix was implanted as small pieces and as thin slices in experimental mandibular osseous defects in dogs. The dentin implants were obtained from mandibular incisor teeth from the same dogs used in the experiment. Experimental interradicular osseous defects were surgically created in the mandibular premolars areas. 2 of the 3 defects were filled with either pieces or slices of prepared dentin. The 3rd defect served as an unfilled control. The results indicate that all demineralized autogenic dentin implants induce bone formation. There was an increase in the osteogenic capacity of the implant when the samples were used as thin slices. The slices of dentin matrix give no evidence of resorption and were readily incorporated into the new bone deposited. The end product was represented by a trabecular bone joined to the dentin matrix slices. In the case of the small piece samples, the specimens were readily resorbed and replaced by new deposits of cancelous bone. The osteogenic capacity of the small piece samples of the dentin matrix is less efficient comparable to the thin slice samples of the same implant material.