The healing capacity and osteogenesis pattern of demineralized dentin matrix (DDM)-fibrin glue (FG) compound.

Demineralized dentin matrix (DDM) is an osteoconductive and osteoinductive material that has been successfully used in sinus floor augmentation and alveolar ridge augmentation in clinical applications. It releases bone morphogenetic proteins (BMPs) and other growth factors, making DDM a suitable grafting material. However, the granular particle of DDM makes it difficult to anchor into the bone defect area. The aim of this study was to investigate the biological effects and osteoinductivity of the combination of DDM and Fibrin Glue (FG) at an optimal ratio on bone healing from a critical bone defect in an animal model. The mouse osteoblastic cell line (MC3T3-E1) was co-cultured with various ratios of DDM and FG to examine their effects on osteoblast proliferation and differentiation, as indicated by alkaline phosphatase (ALP) activity, osteocalcin (OC) production and mineralized nodules formation. The optimal ratio was then chosen for further study with a rabbit calvarial defective model, in which they were implanted with DDM or DDM-FG1 (1 g: 0.1 ml) and DDM-FG2 (1 g: 0.5 ml) compounds, or left blank for 2, 4, 8 and 12 weeks to investigate soft tissue and new bone regeneration. Micro-CT and histology analysis were used to evaluate the total grafting properties according to the different healing periods. The result from in vitro studies demonstrated that the ratio of 1:0.1 induced more ALP activity and mineralized nodules, while the ratio of 1: 0.5 (DDM-FG combined) induced more osteocalcin (OC) at specific time points. In the animal model, the 3D new bone volume in all DDM-FG treatment groups was significantly greater than that in the blank group at 2, 4, 8 and 12 weeks. Furthermore, the new bone volume was greater in DDM-FG2 when compared to the other groups during the early weeks of the healing period. In histological analysis, clusters of osteoblasts were formed adjacent to the DDM particles, and newly formed bone was observed in all groups, suggesting an osteoinductive property of DDM. Moreover, the greater new collagen synthesis observed at 4 weeks suggested that early bone healing was induced in the DDM-FG2 group. This study demonstrated that at an optimal ratio, the DDM-FG compound enhances osteogenic activities and bone regeneration.

Buccal bone dimensional changes at immediate implant sites in the maxillary esthetic zone within a 4-12-month follow-up period: A systematic review and meta-analysis.

OBJECTIVE: To evaluate the changes in buccal bone dimensions (CBD) following immediate implant placement in the maxillary esthetic zone and to identify the factors influencing the degree of buccal bone resorption for different placement and restoration protocols. MATERIAL AND METHODS: An electronic search was conducted using the EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and MEDLINE (PubMed) databases, combined with a manual and gray literature search, up to January 2021. Selected clinical studies had to report the changes in horizontal buccal bone dimension in maxillary immediate implantation sites (premolar to premolar) at baseline and at follow-up visits within a year of implantation. A meta-analysis was conducted to calculate the mean value of the changes in horizontal and vertical buccal bone dimensions (CHBD and CVBD) around implants. To further investigate the heterogeneity and identify factors associated with buccal bone loss after immediate implant placement, subgroup analysis and univariate meta-regression were performed. RESULTS: From a total of 3498 articles, 4 randomized controlled trials and 12 nonrandomized controlled trials were included for analysis. The mean survival rate of 568 implants was 99.6%. The mean CHBD and CVBD values were 0.71 mm (95% confidence interval: [0.56, 0.86]) and 0.58 mm (95% confidence interval: [0.43, 0.72]), respectively. For possible factors that related to bone resorption, including buccal bone thickness, flap design, bone grafting, horizontal defect dimension, and restoration protocol, bone grafting was the only variable that significantly influenced CHBD. CONCLUSIONS: This study demonstrated that immediate implant placement in the esthetic zone does not prevent buccal bone from resorption. Due to data heterogeneity and the small sample size of the studies included in the analysis, further well-conducted, randomized controlled trials with homogeneous samples are required to investigate the correlation of CBD with different variables.

[Application of two-stage ridge splitting technique in atrophic mandibular alveolar ridge].

Adequate bone volume is the primary condition for successful dental implants. However, sufficient bone volume is often encountered in the vertical direction, but the bone volume in the buccolingual direction is insufficient, making it less suitable to be implanted. If the traditional spitting technique is used in the mandible, fracture and necrosis can easily occur in the labial (buccal) bone plate due to the absence of elasticity, thick cortical bone, poor blood supply, and anastomotic branch. The two-stage ridge splitting technique can be used in patients with narrow alveolar ridge in the mandible. This study summarizes the principles and conditions of application, operational points, clinical efficacy, and analysis of the causes of buccal bone plate absorption.

Experimental study of demineralized dentin matrix on osteoinduction and related cells identification / 华西口腔医学杂志

OBJECTIVE@#The aim of this study was to explore the theoretical framework of cells and the forms of osteogenesis in the mechanism by which demineralized dentin matrix (DDM) induces osteogenesis.@*METHODS@#A total of 24 New Zealand rabbits were used in this study. A total of 4 erector spinae bags were created in each animal. A total of 3 erector spinae bags were implanted with DDM by random selection, whereas the remaining one erector spinae bag was not implanted with DDM. The rabbits were sacrificed after 1, 2, 3, 4, 8, 12, 16, and 20 weeks, and the samples were obtained. The samples were examined by hematoxylin-eosin (HE), tartrate-resistant acid phosphatase (TRAP), and immunohistochemical staining to identify the mesenchymal stem cells, osteoblasts, chondrocytes, and osteoclasts.@*RESULTS@#The results of HE staining showed that in the third week, cartilage- and bone-like matrices, as well as the osteoblast-like cells, were observed. The results of immunohistochemical staining showed that the expressions of CD44, alkaline phosphatase (ALP), and collagen Ⅱ were statistically significant 
(P<0.05).@*CONCLUSIONS@#DDM has good histocompatibility and osteoinduction. In addition, induced ectopic osteogenesis mode mainly occurs in the endochondral bone.

[Applications of minimally invasive bone splitting technique in cases with missing maxillary anterior teeth and obvious labial alveolar bone depression for dental implantation].

PURPOSE: The purpose of this study was to introduce a minimally invasive bone splitting technique which is suitable for cases with missing anterior teeth and obvious depression of alveolar bone in labial side, and to evaluate its clinical results. METHODS: Minimally invasive bone splitting technique was used in 8 healthy adults with bone defects in the aesthetic zone. The labial alveolar bone incisions were confined around the bone defects which were smaller than traditional incisions. The other procedures were the same as conventional bone splitting technique. Cone-beam CT (CBCT) for missing anterior teeth was taken before surgery, after the surgery and 6 months after surgery and alveolar bone height and width were recorded with landmark identification designed by ourselves in this study. The data were analyzed with SPSS 21.0 software package for paired t test. RESULTS: Paired t test indicated that after surgery and six months after surgery, the labial bone defect was significant improved (P<0.05), but the height of the alveolar ridge bone didn't increase significantly (P>0.05) while the width of the alveolar ridge bone significant improved (P>0.05). CONCLUSIONS: This minimally invasive technique can achieve good clinical results for not only intact labial alveolar ridge bones but also good bone grafts, which is beneficial to implantation and prosthetic aesthetics. The long-term outcome needs to be observed.