Demineralized Dentin Matrix as a Carrier of Recombinant Human Bone Morphogenetic Proteins: in Vivo Study

Review of Allogeneic Dentin Graft for Maxillofacial Bone Defects

Although autogenous demineralized dentin matrix (auto-DDM) has shown promising clinical and histological results, it has certain limitations beyond its osteoinductivity and osteoconductivity. Therefore, the application of dentin graft material from other individuals-allogeneic DDM (allo-DDM)-has been considered an alternative to auto-DDM. However, few studies have investigated the osteoinductivity and antigenicity of allo-DDM. Herein, we reviewed all human studies related to allogeneic dentin application for the management of maxillofacial bone defects. Clinical studies have shown the osteoinductivity of allo-DDM in extraskeletal and skeletal sites, regardless of occasional antigenicity. Impact statement Although autogenous demineralized dentin matrix (auto-DDM) has shown promising clinical and histological results, it has certain limitations beyond its proven osteoinductivity and osteoconductivity. Therefore, the application of dentin graft material from other individuals-allogeneic DDM (allo-DDM)-has been considered as an alternative to auto-DDM. However, few studies have investigated the osteoinductivity and antigenicity of allo-DDM. This is the first review of all human studies related to allogeneic dentin grafts for the management of maxillofacial bone defects. Clinical studies have shown the osteoinductivity of allo-DDM in extraskeletal and skeletal sites, regardless of occasional antigenicity.

Autogenous Mineralized Dentin versus Xenograft granules in Ridge Preservation for Delayed Implantation in Post-extraction Sites: A Randomized controlled clinical trial with an 18 months follow-up

OBJECTIVES

To test primary stability of delayed implants placed in post-extraction ridges preserved with autogenous mineralized dentin matrix (MDM) versus xenograft granules. Clinical, histological and pain experience outcomes were further assessed.

MATERIAL AND METHODS

From March 2018 to July 2020, patients requiring ridge preservation in preparation for delayed implant placement in post-extraction sites were included. Participants were randomly allocated to either the test (MDM) or control group (xenograft granules) prior to ridge preservation. Visual analogue scale and analgesic consumption were measured every day for a week. Six months after preservation, trephine cores were harvested for histomorphometry prior to implant placement. Implants were then placed, and implant stability was measured immediately as well as two months after placement. Marginal bone loss and presence of mucositis/peri-implantitis were registered up to 18 months after prosthetic loading.

RESULTS

Fifty-two patients (66 implants) completed the study. MDM and xenograft groups presented similar primary (77.1 ± 6.9 versus. 77.0 versus. 5.9) and secondary (81.8 ± 5.1 versus. 80.1 ± 3.8) implant stabilities. The percentage of newly formed bone in MDM (47.3%) was significantly higher than xenograft (34.9%) (p < .001), and the proportion of residual graft was significantly lower (12.2% in MDM and 22.1% in xenograft) (p < .001). No significant differences were found as far as clinical, radiographic and patient-related outcomes.

CONCLUSIONS

Implants placed in sites preserved with MDM had similar primary stability in comparison to xenograft granules. MDM showed a significantly higher quantity of newly formed bone and lower amount of residual graft in histomorphometry results and equal clinical and patient-related outcomes.

Allogeneic Dentin Graft: A Review on Its Osteoinductivity and Antigenicity

Studies on allogeneic demineralized dentin matrix (Allo-DDM) implantation in the 1960s and 1970s provided the most reliable preclinical evidence of bone formation and antigenicity in an extraosseous site. Recently, applications of Allo-DDM at skeletal sites were studied, and have provided reliable evidence of bone-forming capacity and negligible antigenicity. However, the osteoinductivity and antigenicity properties of Allo-DDM in extraskeletal sites have not yet been investigated due to the lack of follow-up studies after the initial research. The clinical applications of autogenous DDM (Auto-DDM) have been standardized in some countries. Long-term clinical studies have reported the development of several shapes of Auto-DDM, such as powders, blocks, moldable forms, and composites, with recombinant human bone morphogenetic protein-2. For the development of Allo-DDM as a reliable bone graft substitute next to Auto-DDM, we reviewed preclinical studies on the bone induction capacity of allogeneic dentin at extraskeletal as well as skeletal sites. Electronic databases were screened for this review in January 2020 and searched from 1960 to 2019. This review aims to provide a foundation on the preclinical studies of Allo-DDM, which could enable future researches on its osteogenic capability and antigenicity. In conclusion, Allo-DDM showed great potential for osteoinductivity in extraskeletal sites with low antigenicity, which neither adversely affected osteogenic capability nor provoked immunologic reactions. However, the risk of viral disease transmission should be researched before the clinical application of Allo-DDM.

Histological Review of Demineralized Dentin Matrix as a Carrier of rhBMP-2

In 2007, recombinant human bone morphogenetic protein-2 (rhBMP-2) was approved for use in humans at a concentration of 1.5 mg/mL with absorbable collagen sponges as an alternative to autogenous bone grafts for alveolar ridge augmentation, defects associated with extraction sockets, and sinus augmentation. However, the use of supraphysiological doses and the insufficient retention of rhBMP-2, when delivered through collagen sponge, result in dose-dependent side effects related to off-label use. Demineralized dentin matrix (DDM), an osteoinducing bone substrate, has been used as an rhBMP-2 carrier since 1998. In addition, DDM has both microparticle and nanoparticle structures, which do not undergo remodeling, unlike bone. In vitro, DDM is a suitable carrier for BMP-2, with the continued release over 30 days at concentrations sufficient to stimulate osteogenic differentiation. In this review, we discuss the histological outcomes of DDM loaded with rhBMP-2 to highlight the biological functions of exogenous rhBMP-2 associated with the DDM carrier in clinical applications in implant dentistry. Impact Statement Demineralized dentin matrix (DDM) has been used as an recombinant human bone morphogenetic protein (rhBMP-2) carrier and osteo-inducing bone substrate to facilitate continued release and stimulate osteogenic differentiation. In this review, we discuss the histological outcomes of DDM loaded with rhBMP-2 in order to highlight the biological functions of exogenous rhBMP-2 associated with the DDM carrier in clinical applications in implant dentistry.

Postulated release profile of recombinant human bone morphogenetic protein-2 (rhBMP-2) from demineralized dentin matrix

Demineralized dentin matrix (DDM) has been used as a recombinant human bone morphogenetic protein-2 (rhBMP-2) carrier in many clinical trials. To optimize the clinical safety and efficacy of rhBMP-2 with DDM, efforts have been made to improve the delivery of rhBMP-2 by 1) lowering the administered dose, 2) localizing the protein, and 3) prolonging its retention time at the action site as well as the bone forming capacity of the carrier itself. The release profile of rhBMP-2 that is associated with endogenous BMP in dentin has been postulated according to the type of incorporation, which is attributed to the loosened interfibrillar space and nanoporous dentinal tubule pores. Physically adsorbed and modified, physically entrapped rhBMP-2 is sequentially released from the DDM surface during the early stage of implantation. As DDM degradation progresses, the loosened interfibrillar space and enlarged dentinal tubules release the entrapped rhBMP-2. Finally, the endogenous BMP in dentin is released with osteoclastic dentin resorption. According to the postulated release profile, DDM can therefore be used in a controlled manner as a sequential delivery scaffold for rhBMP-2, thus sustaining the rhBMP-2 concentration for a prolonged period due to localization. In addition, we attempted to determine how to lower the rhBMP-2 concentration to 0.2 mg/mL, which is lower than the approved 1.5 mg/mL.

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.

Measurement of hepatitis B virus DNA in fresh versus processed dentin from chronically infected patients

BACKGROUND

Demineralized dentin matrix (DDM) is commonly used as a bone-graft substitute. This study measured and compared human hepatitis B viruses (HBV) DNA in fresh dentin to that of dentin processed into DDM extracted during dental treatment from HBV-infected patients. The hypothesis was that the processing procedure for DDM would inactivate or eliminate HBV in the dentin matrix obtained from infected patients.

METHODS

Dentin from eighteen HBV-infected patients was collected and each dentin specimen was divided into two fragments. One fragment was used before processing as fresh dentin (control group) and the other was processed into DDM (experimental group). DNA was extracted and purified from each fresh and processed dentin specimen and the HBV DNA copy number quantitated by real time polymerase chain reaction. The HBV DNA copy number in the fresh dentin specimens were compared relative to serologic test results. The second parameter was to evaluate the effectiveness of the processing procedure (defatting, demineralization, freeze-drying, and sterilization) to inactivate or eliminate HBV by comparing the DNA copy number in the processed DDM with that in the matched fresh dentin specimens. All results were analyzed using Mann-Whitney U test to compare numerical measurements between groups and differences were considered statistically significant at P-values less than 0.05.

RESULTS

The presence of HBV DNA was detected in 55.56% (10/18) of the fresh dentin specimens. For the ten HBV DNA-positive fresh dentin specimens, HBV DNA was detected in two (20%) of the matched processed dentin specimens. The copy number of HBV DNA in the two positive processed dentin specimens was 1.79 and 4.03, which were statistically lower than that of the fresh dentin specimens (P = 0.0167).

CONCLUSIONS

The results from this study suggested that fresh dentin may be a carrier of HBV and that the procedure used to generate DDM extensively reduced the levels of HBV DNA. Further studies are needed to evaluate the infectivity of HBV in processed dentin.