In Vivo Analyses of Osteogenic Activity and Bone Regeneration Capacity of Demineralized Freeze-Dried Bovine Bone Xenograft: A Potential Candidate for Alveolar Bone Fillers

Preosteoblast Adhesion and Viability Study of Freeze-Dried Bovine Bone Block Scaffold Coated with Human Umbilical Cord Mesenchymal Stem Cell Secretome

OBJECTIVES

 Combining a three-dimensional scaffold with growth factors before implantation is one method used to increase scaffold bioactivity in bone tissue engineering. The mesenchymal stem cell (MSC)-conditioned medium (CM), called secretome, contains many proteins and growth factors required for tissue repair and growth. This study evaluated the bioactivity of a bovine bone scaffold combined with the secretome of human umbilical cord MSCs (hUC-MSCs) by analyzing MC3T3-E1 cell adhesion and viability on the scaffold.

MATERIALS AND METHODS

 This in vitro laboratory study evaluated the effect of hUC-MSC secretome applied to bovine bone scaffolds processed using various techniques on MC3T3-E1 cell adhesion and viability. The three experimental groups included deproteinized bovine bone mineral-secretome (DBBM-CM), freeze-dried bovine bone-secretome (FDBB-CM), and decellularized FDBB-CM, whereas the control group was treated with DBBM alone. The cell adhesion test was performed using the centrifugation method after 6 and 24 hours, whereas the cell viability test was conducted using the trypan blue exclusion method after 24, 48, and 72 hours. Cell attachment was visualized after 4',6-diamidino-2-phenylindole staining and viewed under inverted fluorescence microscopy.

STASTICAL ANALYSIS

 Statistical analyses were performed using one-way analysis of variance, followed by a post hoc test in cases of significant differences.

RESULTS

 Statistical analyses showed significantly greater adhesion of the preosteoblasts to the FDBB-CM scaffold at 6 hours (p = 0.002). The results of the adhesion test at 24 hours and the viability tests at all observation times showed no significant differences (p > 0.05). This study found that the average MC3T3-E1 cell adhesions and viabilities were highest for the FDBB-CM and DBBM-CM scaffolds. DBBM scaffolds with the secretome had better cell adhesion and viability than those without the secretome.

CONCLUSION

 The addition of MSC secretome increased bovine bone scaffold bioactivity especially in DBBM and FDBB scaffolds.

A Zinc Oxide Nanowire-Modified Mineralized Collagen Scaffold Promotes Infectious Bone Regeneration

Bone infection poses a major clinical challenge that can hinder patient recovery and exacerbate postoperative complications. This study has developed a bioactive composite scaffold through the co-assembly and intrafibrillar mineralization of collagen fibrils and zinc oxide (ZnO) nanowires (IMC/ZnO). The IMC/ZnO exhibits bone-like hierarchical structures and enhances capabilities for osteogenesis, antibacterial activity, and bacteria-infected bone healing. During co-cultivation with human bone marrow mesenchymal stem cells (BMMSCs), the IMC/ZnO improves BMMSC adhesion, proliferation, and osteogenic differentiation even under inflammatory conditions. Moreover, it suppresses the activity of Gram-negative Porphyromonas gingivalis and Gram-positive Streptococcus mutans by releasing zinc ions within the acidic infectious microenvironment. In vivo, the IMC/ZnO enables near-complete healing of infected bone defects within the intricate oral bacterial milieu, which is attributed to IMC/ZnO orchestrating M2 macrophage polarization, and fostering an osteogenic and anti-inflammatory microenvironment. Overall, these findings demonstrate the promise of the bioactive scaffold IMC/ZnO for treating bacteria-infected bone defects.

Evaluation of deproteinised bovine bone matrix combined with absorbable biofilm for the preservation of extraction sites of mandibular impacted wisdom teeth

BACKGROUND

Bone defects and deep periodontal pockets often exist distal to the second molar after mandibular third molar extraction, seriously threatening the periodontal health of the second molar.

OBJECTIVE

To evaluate the effect of socket preservation with bone substitute materials on alveolar bone resorption and prevention of the distal periodontal defect of the adjacent tooth after mandibular impacted third molar extraction compared with natural healing.

METHODS

Ninety-nine patients with mandibular impacted teeth, treated in our hospital from January 2018 to December 2020, were randomly divided into the control and experimental groups. The experimental group underwent minimally invasive tooth extraction and socket preservation using the deproteinised bovine bone mineral, Bio-Oss and the bioabsorbable collagen membrane, Bio-Gide. The control group healed naturally after minimally invasive tooth extraction. The alveolar ridge dimension of the extraction sites, the probing depth, tooth mobility and gingival index on the distal aspect of the mandibular second molars were examined and recorded before and six months after the operations.

RESULTS

There was a significant difference between the experimental group and the control group in the alveolar bone width (P< 0.05) and height (P< 0.05) before and after surgery. The probing depth of the extraction sites in both groups was reduced.

CONCLUSION

Using Bio-Oss and Bio-Gide to preserve extraction sites of impacted teeth can promote recovery more effectively than natural healing on the height of the distal alveolar bone and the width of the alveolar crest of the second molar and thus improve the periodontal status of the adjacent second molar.

The Osteogenesis Mechanisms of Dental Alveolar Bone Socket Post Induction with Hydroxyapatite Bovine Tooth Graft: An Animal Experimental in Rattus norvegicus Strain Wistar

OBJECTIVES

 Surgical endodontics (hemisection) commonly involves the alveolar bone socket and the periradicular tissue. In today's era, optimizing the bone healing process is updated by using bone graft induction. This study explores the mechanisms of bone healing of the alveolar bone socket post-dental extraction of Wistar rats after administration of a bovine tooth graft (hydroxyapatite bovine tooth graft [HAp-BTG]).

MATERIALS AND METHODS

 Fifty Wistar rats were randomly selected into two groups, control and treatment, and into five subgroups on days 3, 7, 14, 21, and 28. The postextraction socket was filled with polyethylene glycol (PEG) as the control and PEG + HAp-BTG as the treatment group. On days 3, 7, 14, 21, and 28, Wistar rats were sacrificed, mandibles were taken, paraffin blocks were made, cut 4 µm thick, and made into glass preparations for microscopic examination. The variable analysis was performed by staining hematoxylin-eosin for osteoblasts (OBs) and osteoclasts (OCs) and immunohistochemistry for runt-related transcription factor 2 (RUNX2), osterix (OSX), osteocalcin (OCN), bone morphogenic protein (BMP) 2. We analyzed the expressed cell count per microscope field.

RESULTS

 In general, the number of cell expressions in the treatment group was significantly higher and faster, except for significantly lower OC. The high variables peak occurred on day 14 for RUNX2 and OCN, on day 7 for OSX, while OB significantly increased on day 21 and remained until day 28. The decrease of OC cells occurred on day 7 and remained low until 28 days. BMP2 was first dominantly induced by HAp-BTG, then the others.

CONCLUSION

 HAp-BTG can induce higher and faster bone healing biomarkers. BMP2 is the dominant first impacted. On the 28th day, it did not significantly express the suppression of OC by OB, which entered the bone formation and remodeling step.

Bone Augmentation for Implant Placement: Recent Advances

There are various advancements in biomaterials and methods for bone augmentation. This article aims to review the recent advances in bone augmentation for dental implants. Relevant articles on bone augmentation for dental implants were searched in PubMed/Medline, Scopus, Google Scholar, and Science Direct published in English literature published between January 1996 and March 2021. Relevant studies on bone grafts for dental implants were included and critically analyzed in this review. Various biomaterials can be used to augment bone for implant placement. Each graft procedure has advantages and disadvantages in each clinical application and needs to choose the graft material with a high success rate and less morbidity.

Evaluation of regeneration after the application of 2 types of deproteinized bovine bone mineral to alveolar bone defects in adult dogs

Purpose

The aim of this study was to evaluate the preclinical results of 2 types of commercially available deproteinized bovine bone mineral (DBBM) when applied to alveolar bone defects in dogs.

Methods

This study was conducted using 6 beagles. Alveolar defects in the mandible were formed and filled with 2 DBBMs produced by a similar procedure. Defects were randomly assigned to be filled using DBBM 1 or 2. All defects were covered with a collagen membrane and had a healing period of 12 weeks. After the dogs were sacrificed, histological, histomorphometric, and linear/volumetric analyses were performed.

Results

Both DBBM groups showed similar histological findings, demonstrating that bone remodeling had occurred and new bone had formed. The residual bone particles were surrounded by newly formed vital bone. In the histomorphometric analysis, the ratio of the area of vital bone and residual bone substitute in DBBM 2 (38.18% and 3.47%, respectively) was higher than that of DBBM 1 (33.74% and 3.41%, respectively), although the difference was not statistically significant. There were also no statistically significant differences between both groups in linear and volumetric analyses using micro-computed tomography scans and digitized images of dental casts.

Conclusions

In the present study, DBBM 1and 2, which were produced by similar processes, showed similar results in histological, histomorphometric, and volumetric analyses. Further studies are needed to identify more specific differences between the 2 DBBMs.