DBBM shows no signs of resorption under inflammatory conditions. An experimental study in the mouse calvaria

Effect of Applying 1% Metformin on Guided Bone Regeneration Processes with Bovine-Derived Xenografts

Background: Although xenografts have shown successful results in GBR procedures due to their osteoconductive properties, many authors have opted to add co-adjuvant drugs to favor osteogenesis and differentiate cells into an osteoblastic lineage. Metformin has been shown to have bone-protective properties, regulating osteoclast differentiation, as well as the ability to promote osteoblast mineralization and differentiation. The present study aimed to evaluate the effect of the local application of a 1% metformin solution on bone neoformation in the treatment of an experimental bone defect in a guided bone regeneration animal model with a particulated bovine hydroxyapatite xenograft with hyaluronate. Methods: With this purpose in mind, two critical defects with 8 mm diameter and 0.5 mm depth were created in eight male New Zealand rabbit calvarias. Titanium cylinders were fixed in each defect and filled with particulate hydroxyapatite of bovine origin and sodium hyaluronate, with sterile injectable saline added to the control group and sterile 1% metformin solution added to the test group. At 6 weeks, the animals were euthanized, and samples were obtained and prepared for histomorphometric analysis. Results: A higher percentage of new bone formation was observed in the metformin samples than in the control samples, both in the region closest to the animal's calvaria and in the most distal region analyzed. A higher average bone-biomaterial contact percentage was observed in the samples, with metformin in both the proximal and distal regions. There was no statistically significant difference in the mean value in either region in both parameters. Conclusion: The local application of a 1% metformin solution in an animal model of guided bone regeneration with particulate bovine hydroxyapatite and hyaluronate resulted in greater bone neoformation and xenograft osseointegration than in the control group.

CBCT for Diagnostics, Treatment Planning and Monitoring of Sinus Floor Elevation Procedures

Sinus floor elevation (SFE) is a standard surgical technique used to compensate for alveolar bone resorption in the posterior maxilla. Such a surgical procedure requires radiographic imaging pre- and postoperatively for diagnosis, treatment planning, and outcome assessment. Cone beam computed tomography (CBCT) has become a well-established imaging modality in the dentomaxillofacial region. The following narrative review is aimed to provide clinicians with an overview of the role of three-dimensional (3D) CBCT imaging for diagnostics, treatment planning, and postoperative monitoring of SFE procedures. CBCT imaging prior to SFE provides surgeons with a more detailed view of the surgical site, allows for the detection of potential pathologies three-dimensionally, and helps to virtually plan the procedure more precisely while reducing patient morbidity. In addition, it serves as a useful follow-up tool for assessing sinus and bone graft changes. Meanwhile, using CBCT imaging has to be standardized and justified based on the recognized diagnostic imaging guidelines, taking into account both the technical and clinical considerations. Future studies are recommended to incorporate artificial intelligence-based solutions for automating and standardizing the diagnostic and decision-making process in the context of SFE procedures to further improve the standards of patient care.

Niobium-containing bioactive glasses modulate alkaline phosphatase activity during bone repair

This study aimed to evaluate the pre-clinical behavior of niobium-containing bioactive glasses (BAGNb) by their ability to promote bone repair and regulate alkaline phosphatase (ALP) levels in an animal model. BAGNbs were produced as powders and as scaffolds and surgically implanted in the femur of male rats (Wistar lineage n = 10). Glasses without Nb (BAG) were produced and implanted as well. The Autogenous Bone (AB) was used as a control. After 15, 30, and 60 days of surgical implantation, blood serum samples were collected to quantify ALP activity, and femurs were removed to assess bone repair. Bone samples were histologically processed and stained with H&E to quantify the % new bone into defects. No postoperative complications were identified. Early-stage repair (15 days) resulted in increased ALP activity for all groups, with increased values ​​for powdered BAGNb. The maturation of the new bone led to a reduction in serum ALP levels. Histological sections showed the formation of immature bone tissue and vascularization with the progression of bone deposition to mature and functional tissue over time. BAG powder showed less new bone formation in 15 days, while the analysis at 30 and 60 days showed no difference between groups (p > .05). Niobium-containing bioactive glasses safely and successfully induced bone repair in vivo. The modulation of ALP activity may be a pathway to describe the ability of niobium-containing materials to contribute to new bone formation.

Influence of the bone graft materials used for guided bone regeneration on subsequent peri-implant inflammation: an experimental ligature-induced peri-implantitis model in Beagle dogs

Purpose

We aimed to histologically evaluate the influence of bone materials used during guided bone regeneration (GBR) on subsequent peri-implantitis in an experimental ligature-induced peri-implantitis model in beagle dogs.

Methods

Bilateral mandibular premolars (PM2-4) were extracted from six beagle dogs. After 3 months, standardized bone defects (3 mm [mesio-distal width] × 2 mm [bucco-lingual width] × 3 mm [depth]) were created in the experimental group, with simultaneous dental implant placement at the center of the defects. The defects were randomly filled with either autograft (AG) or deproteinized bovine bone mineral (DBBM) and covered with a collagen membrane. In the control group, implant fixtures were placed without creating an intrabony defect. After 3 months, a healing abutment was placed. Four weeks later, a 3–0 silk thread was ligated around the implants to induce peri-implantitis. After 4 weeks, the specimens were dissected and histologically examined.

Results

There were no clinical findings of inflammation until silk thread ligation. Four weeks after the onset of peri-implantitis, gingival redness and swelling were seen with mild resorption of the peri-implant bone on dental radiographs. There were no significant differences between the AG, DBBM, and control groups for the following parameters: bone-to-implant contact, distance from the implant shoulder to the base of the bone defect, area of bone defect, and area of new bone.

Conclusions

Within the limitations of this study, it can be concluded that peri-implant tissues after GBR using AG and DBBM underwent the same degree of bone resorption by peri-implantitis as the no defect group.

3D printing of poly(butylene adipate-co-terephthalate) (PBAT)/niobium containing bioactive glasses (BAGNb) scaffolds: Characterization of composites, in vitro bioactivity, and in vivo bone repair

This study aimed to produce poly(butylene adipate-co-terephthalate) (PBAT)/niobium containing bioactive glasses (BAGNb) composites scaffolds produced by fused deposition modeling (FDM) printing and evaluate their physicochemical and biological properties in vitro and in vivo. The composite filaments were produced by melt-extrusion with the addition of 10 wt% of BAGNb (PBAT/BAGNb). Filaments without BAGNb were produced as the control group (PBAT). The filaments were characterized and were used to produce 3D-printed scaffolds using FDM. The scaffolds' structure and surface properties were assessed. In vitro cell, proliferation, and cell mineralization analysis were performed. In vivo data was obtained in the rat femur model (n = 10), and the bone repair was assessed after 15, 30, and 60 postoperative days. The printed structures presented 69.81% porosity for the PBAT/BAGNb group and 74.54% for the PBAT group. Higher cell mineralization was observed for the PBAT/BAGNb group. The in vivo data showed that the PBAT/BAGNb presented new bone formation comparable to positive controls. The combination of PBAT and BAGNb in 3D-printed scaffolds may be an alternative to produce bioactive materials with controllable shapes and properties for bone regeneration treatments.

Histological and Histomorphometric Evaluation of Applying a Bioactive Advanced Platelet-Rich Fibrin to a Perforated Schneiderian Membrane in a Maxillary Sinus Elevation Model

Background

Schneiderian membrane (SM) perforation is a major complication of maxillary sinus elevation with simultaneous bone grafting, yet under this scenario there is no standard biomaterial that maximizes favorable tissue healing and osteogenic effects.

Purpose

To compare the effect of advanced platelet-rich fibrin (A-PRF) and collagen membrane (CM) on a perforated SM with simultaneous bone grafting in a maxillary sinus elevation model.

Materials and Methods

After perforation of the SM was established, 24 animals were randomly divided into two groups: (i) group CM: CM and deproteinized bovine bone mineral (DBBM) (n = 12), (ii) group A-PRF: A-PRF and DBBM (n = 12). Radiographic and histological evaluations were performed at 1 and 4 weeks post-operation.

Results

At 1 week, an intact SM was found in group A-PRF. At each time point, the number of inflammatory cells at the perforated site was higher in group CM, and the area of new osteoid formation was significantly greater in group A-PRF (p < 0.0001). At 4 weeks, the osteogenic pattern was shown as from the periphery to the center of the sinus cavity in group A-PRF.

Conclusion

The higher elasticity, matching degradability, and plentiful growth factors of A-PRF resulted in a fully repaired SM, which later ensured the two osteogenic sources from the SM to generate significant new bone formation. Thus, A-PRF can be considered to be a useful bioactive tissue-healing biomaterial for SM perforation with simultaneous bone grafting.

Impact of DBBM Fragments on the Porosity of the Calvarial Bone: A Pilot Study on Mice

Deproteinized bovine bone mineral (DBBM) is brittle and can break into fragments. Here, we examined whether DBBM fragments have an impact on mice calvarial bone during bone augmentation. DBBM was either randomly crushed (DBBM fragments) or left undisturbed (DBBM granules). Then, DBBM fragments or original DBBM granules were placed onto calvarial bone in 20 BALB/c mice. Following random allocation, ten mice received DBBM fragments and ten mice received original DBBM granules. After fourteen days of healing, micro computed tomography (micro-CT) and histological analysis of the augmented sites were performed. The primary outcome was the porosity of the calvarial bone. The micro-CT analysis revealed that DBBM fragments failed to significantly change the porosity of the calvarial bone as compared with original DBBM granules, despite the slightly higher bone resorption in the DBBM fragment group, 10.3% (CI 6.3–11.6) versus 6.1% (CI 4.1–7.8, p = 0.355), respectively. The cortical bone volume was not altered by DBBM fragments as compared with original DBBM granules, i.e., 79.0% (CI 78.9–81.2) versus 81.5% (CI 80.1–83.3, p = 0.357), respectively. The DBBM fragment group revealed similar bone thickness values as compared with the DBBM granules group, i.e., 0.26 mm (CI 0.23–0.29) versus 0.25 mm (CI 0.22–0.27, p = 0.641), respectively. The histological evaluation supported the micro-CT observations, displaying minor signs of porosity and resorption. The particle-size distribution analysis confirmed a shift towards smaller particle sizes in the DBBM fragment group. These findings suggest that DBBM fragments behave similarly to original DBBM granules in terms of bone morphological changes at augmented sites.

DBBM shows no signs of resorption under inflammatory conditions. An experimental study in the mouse calvaria

OBJECTIVES

Deproteinized bovine bone mineral (DBBM) is not resorbable. However, the behavior of DBBM under inflammatory conditions remains unclear. Aim of the study was therefore to evaluate the resorption of DBBM under local inflammatory conditions in vivo using the calvarial osteolysis model.

METHODS

In thirty adult BALB/c mice, DBBM was implanted into the space between the elevated soft tissue and the calvarial bone. Inflammation was induced either by lipopolysaccharides (LPS) injection or by polyethylene particles (Ceridust) mixed with DBBM. Three modalities were randomly applied (n = 10 each): (a) DBBM alone (control), (b) DBBM + LPS, and (c) DBBM + polyethylene particles (Ceridust). Mice were euthanized on day fourteen, and each calvarium was subjected to histological and µCT analysis. Primary outcome was the size distribution of the DBBM particles. Secondary outcome was the surface erosion of the calvarial bone.

RESULTS

Histological and µCT analysis revealed that the size distribution and the volume of DBBM particles in the augmented site were similar between DBBM alone and the combinations with LPS or polyethylene particles. Moreover, histological evaluation showed no signs of erosions of DBBM particles under inflammatory conditions. µCT analysis and histology further revealed that LPS and the polyethylene particles, but not the DBBM alone, caused severe erosions of the calvarial bone as indicated by large voids representing the massive compensatory new immature woven bone formation on the endosteal surface.

CONCLUSIONS

Local calvarial bone but not the DBBM particles undergo severe resorption and subsequent new bone formation under inflammatory conditions in a mouse model.