Guided bone regeneration using beta-tricalcium phosphate with and without fibronectin-An experimental study in rats

Guided bone regeneration using beta-tricalcium phosphate and leucocyte platelet-rich fibrin versus a novel biodegradable urethane composite in critical-size osseous defects in rabbit tibia: Histologic results of a pilot study

BACKGROUND

Insufficient bone volume is a major problem in implant dentistry, which can be counteracted by using guided bone regeneration technique. Among the materials recently tested, synthetic polymers have been recommended as showing excellent biocompatibility and biodegradability.

OBJECTIVE

The aim of this pilot study was to analyze and compare through means of histology the healing of the bone tissue in critical size osseous defects in New-Zealand rabbit tibiae after application of beta-tricalcium phosphate (β-TCP) alone, β-TCP combined with leucocyte platelet-rich fibrin (L-PRF) and an injectable experimental bone cement (EBC) represented by a dual-curable degradable synthetic polymer.

METHODS

Two New-Zealand rabbits were used. Three standardized osseous defects of 5 mm diameter were created in each tibia. Each defect was filled with either β-TCP alone (control), β-TCP combined with L-PRF (test) or with EBC (test). The animals were sacrificed at 25 and 70 days; the tibia samples were removed, fixed in 10 % formaldehyde and stained with AZAN.

RESULTS

While at 25 days β-TCP produced sparse bone formation, at 70 days mature bone formation was visible in all areas of the defect with minimum remaining graft particles; at 25 days, β-TCP combined with L-PRF produced broad areas of bone lamellae, while at 70 days bone tissue formation was limited; at both 25 and 70 days, the EBC was stable and not penetrated by bone cells, while a narrow band of connective tissue could be seen superjacent and inferior to it.

CONCLUSIONS

Among the tested biomaterials, β-TCP was capable of generating bone formation at both healing time-points, while the addition of L-PRF seemed to provide a synergistic effect only in the early phase of bone healing.

Histomorphometric Assessment of Non-Decalcified Plastic-Embedded Specimens for Evaluation of Bone Regeneration Using Bone Substitute Materials-A Systematic Review

With the implementation of bone substitute materials, regeneration strategies have inevitably evolved over the years. Histomorphometry is the optimal means of quantitative evaluation of bone structure and morphology. This systematic review focuses on determining study models, staining methods and histomorphometric parameters used for bone regeneration research on non-decalcified plastic-embedded specimens over the last 10 years. After being subjected to the inclusion and exclusion criteria, 118 studies were included in this review. The results establish the most commonly selected animal model is rat, followed by rabbit, sheep and dog. Strong preference for staining samples with toluidine blue was noted. With regard to histomorphometric parameters, terms related to bone were most frequently assessed, amounting to almost half of recorded parameters. New bone formation was the main descriptor of this category. Residual bone graft and non-bone tissue parameters were also often evaluated. With regard to dynamic histomorphometry, mineral apposition rate (MAR) was the parameter of choice for most researchers, with calcein green being the preferred dye for fluorochrome labelling. An overview of the contemporary literature, as well as weaknesses in the current research protocols have been discussed.

Combination of a Synthetic Bioceramic Associated with a Polydioxanone-Based Membrane as an Alternative to Autogenous Bone Grafting

The purpose of this study was to evaluate the repair process in rat calvaria filled with synthetic biphasic bioceramics (Plenum® Osshp-70:30, HA:βTCP) or autogenous bone, covered with a polydioxanone membrane (PDO). A total of 48 rats were divided into two groups (n = 24): particulate autogenous bone + Plenum® Guide (AUTOPT+PG) or Plenum® Osshp + Plenum® Guide (PO+PG). A defect was created in the calvaria, filled with the grafts, and covered with a PDO membrane, and euthanasia took place at 7, 30, and 60 days. Micro-CT showed no statistical difference between the groups, but there was an increase in bone volume (56.26%), the number of trabeculae (2.76 mm), and intersection surface (26.76 mm2) and a decrease in total porosity (43.79%) in the PO+PG group, as well as higher values for the daily mineral apposition rate (7.16 µm/day). Histometric analysis presented material replacement and increased bone formation at 30 days compared to 7 days in both groups. Immunostaining showed a similar pattern between the groups, with an increase in proteins related to bone remodeling and formation. In conclusion, Plenum® Osshp + Plenum® Guide showed similar and sometimes superior results when compared to autogenous bone, making it a competent option as a bone substitute.

Characterization of Polyvinyl Alcohol-Collagen-Hydroxyapatite Composite Membrane from Lates calcarifer Scales for Guided Tissue and Bone Regeneration

OBJECTIVE

 To determine the chemical structure, tensile strength, porosity, and degradability of polyvinyl alcohol (PVA)-collagen-hydroxyapatite (HA) composite membranes for guided tissue and bone regeneration.

MATERIALS AND METHODS

 The PVA-collagen-HA composite membrane was divided into three groups: the group without irradiation, the group with 15 kGy irradiation, and 25 kGy irradiation. Each group was tested for chemical structure with Fourier-transform infrared (FT-IR) at a wavelength of 400 to 4,000 cm-1. Tensile strength test was tested in dry and wet conditions with the standard method of American Standard Testing Mechanical (ASTM) D638, and porosity using scanning electron microscope and analyzed using ImageJ software. Degradability test immersed in a solution of phosphate-buffered saline. Data were analyzed using analysis of variance (ANOVA) and Tukey's test.

RESULTS

 FT-IR test before and after storage for 30 days on three media showed a stable chemical structure with the same functional groups. ANOVA analysis showed a significant difference (p < 0.05) in the dry condition (p = 0.006), Tukey's test showed a significant difference in the 15 kGy and 25 kGy irradiated groups (p = 0.005), but the groups without irradiation had no significant difference with the 15 kGy (p = 0.285) and 25 kGy (p = 0.079) irradiation groups. In wet conditions, there was no significant difference (p > 0.05) in each group (p = 373). The size of the porosity in the group without irradiation, 15 kGy irradiation, and 25 kGy irradiation showed a size of 4.65, 6.51, and 8.08 m, respectively. The degradability test showed a decrease in weight in each group, with the total weight of the membrane being completely degraded from the most degraded to the least: the groups without irradiation, 15 kGy irradiation, and 25 kGy irradiation. The ANOVA test on the degradability test shows significant (p < 0.05) in the PVA-collagen-HA composite membrane group over time intervals (p = 0.000). Tukey's post hoc test showed a significant difference (p < 0.05) after 1 week between the groups without irradiation with 15 kGy (p = 0.023).

CONCLUSION

 PVA-collagen-HA composite membrane has a stable chemical structure, optimal tensile strength, porosity, and ideal degradability as guided bone regeneration and guided tissue regeneration.

Molecular Research on Oral Diseases and Related Biomaterials: A Journey from Oral Cell Models to Advanced Regenerative Perspectives

Oral diseases such as gingivitis, periodontitis, and oral cancer affect millions of people worldwide. Much research has been conducted to understand the pathogenetic mechanisms of these diseases and translate this knowledge into therapeutics. This review aims to take the reader on a journey from the initial molecular discoveries to complex regenerative issues in oral medicine. For this, a semi-systematic literature search was carried out in Medline and Web of Science databases to retrieve the primary literature describing oral cell models and biomaterial applications in oral regenerative medicine. First, an in vitro cell model of gingival keratinocytes is discussed, which illustrates patho- and physiologic principles in the context of oral epithelial homeostasis and carcinogenesis and represents a cellular tool to understand biomaterial-based approaches for periodontal tissue regeneration. Consequently, a layered gradient nonwoven (LGN) is described, which demonstrates that the key features of biomaterials serve as candidates for oral tissue regeneration. LGN supports proper tissue formation and obeys the important principles for molecular mechanotransduction. Furthermore, current biomaterial-based tissue regeneration trends, including polymer modifications, cell-based treatments, antimicrobial peptides and optogenetics, are introduced to represent the full spectrum of current approaches to oral disease mitigation and prevention. Altogether, this review is a foray through established and new concepts in oral regenerative medicine and illustrates the process of knowledge translation from basic molecular and cell biological research to future clinical applications.

Fibronectin in Fracture Healing: Biological Mechanisms and Regenerative Avenues

The importance of extracellular matrix (ECM) proteins in mediating bone fracture repair is evident, and fibronectin (FN) has emerged as a pivotal regulator of this process. FN is an evolutionarily conserved glycoprotein found in all tissues of the body, and functions in several stages of fracture healing. FN acts as a three-dimensional scaffold immediately following trauma, guiding the assembly of additional ECM components. Furthermore, FN regulates cellular behavior via integrin-binding and growth factor-binding domains, promoting downstream responses including cell recruitment, proliferation and differentiation. Due to its diverse functions, the development of FN-based strategies to promote fracture healing is under intense research. In this review, we discuss the recent advancements in utilizing FN-based biomaterials, showing promise in tissue engineering and regenerative medicine applications.

Biomimetic titanium implant coated with extracellular matrix enhances and accelerates osteogenesis

Aim: To evaluate the biological function of titanium implants coated with cell-derived mineralized extracellular matrix, which mimics a bony microenvironment. Materials & methods: A biomimetic titanium implant was fabricated primarily by modifying the titanium surface with TiO₂ nanotubes or sand-blasted, acid-etched topography, then was coated with mineralized extracellular matrix constructed by culturing bone marrow mesenchymal stromal cells. The osteogenic ability of biomimetic titanium surface in vitro and in vivo were evaluated. Results: In vitro and in vivo studies revealed that the biomimetic titanium implant enhanced and accelerated osteogenesis of bone marrow stromal cells by increasing cell proliferation and calcium deposition. Conclusion: By combining surface topography modification with biological coating, the results provided a valuable method to produce biomimetic titanium implants with excellent osteogenic ability.

Short time guided bone regeneration using beta-tricalcium phosphate with and without fibronectin - An experimental study in rats

Background

 The aim of this histomorphometric study was to assess the bone regeneration potential of beta-tricalcium phosphate with fibronectin (β-TCP-Fn) in critical-sized defects (CSDs) in rats calvarial, to know whether Fn improves the new bone formation in a short time scope.

Material and Methods

 CSDs were created in 30 Sprague Dawley rats, and divided into four groups (2 or 6 weeks of healing) and type of filling (β-TCP-Fn, β-TCP, empty control). Variables studied were augmented area (AA), gained tissue (GT), mineralized/non mineralized bone matrix (MBM/NMT) and bone substitute (BS).

Results

60 samples at 2 and six weeks were evaluated. AA was higher for treatment groups comparing to controls (p < 0.001) and significant decrease in BS area in the β-TCP-Fn group from 2 to 6 weeks (p = 0.031). GT was higher in the β-TCP-Fn group than in the controls expressed in % (p = 0.028) and in mm2 (p = 0.011), specially at two weeks (p=0.056).

Conclusions

 Both β-TCP biomaterials are effective as compared with bone defects left empty in maintaining the volume. GT in defects regeneration filed with β-TCP-Fn are significantly better in short healing time when comparing with controls but not for β-TCP used alone in rats calvarial CSDs.

Key words:Bone regeneration, biomaterials, experimental design, histology.

Regenerative Effect of Platelet Concentrates in Oral and Craniofacial Regeneration

Platelet concentrates (PCs) are biological autologous products derived from the patient's whole blood and consist mainly of supraphysiologic concentration of platelets and growth factors (GFs). These GFs have anti-inflammatory and healing enhancing properties. Overall, PCs seem to enhance bone and soft tissue healing in alveolar ridge augmentation, periodontal surgery, socket preservation, implant surgery, endodontic regeneration, sinus augmentation, bisphosphonate related osteonecrosis of the jaw (BRONJ), osteoradionecrosis, closure of oroantral communication (OAC), and oral ulcers. On the other hand, no effect was reported for gingival recession and guided tissue regeneration (GTR) procedures. Also, PCs could reduce pain and inflammatory complications in temporomandibular disorders (TMDs), oral ulcers, and extraction sockets. However, these effects have been clinically inconsistent across the literature. Differences in study designs and types of PCs used with variable concentration of platelets, GFs, and leucocytes, as well as different application forms and techniques could explain these contradictory results. This study aims to review the clinical applications of PCs in oral and craniofacial tissue regeneration and the role of their molecular components in tissue healing.