Comparison of a xenogeneic and an alloplastic material used in dental implants in terms of physico-chemical characteristics and in vivo inflammatory response

In Vitro Handling Characteristics of a Particulate Bone Substitute for Ridge Preservation Procedures

While particulate bone substitute materials are applied in a variety of augmentation procedures, standardized defects are being used for preclinical testing. This in vitro study evaluated the density and homogeneity of a particulate bone substitute in ridge preservation procedures. Premolars and molars were extracted in ten semimandibles of minipig cadavers. Light body impression material was used for determining the volume of the extraction sites followed by augmentation with particulate material, thereby weighing the graft material needed. Microradiographs and histologic sections were obtained for evaluating the homogeneity and density of the augmentation material. Statistical analyses were based on Shapiro-Wilk tests, Spearman's rho and one sample Wilcoxon test followed by Bonferroni-Holm correction for multiple testing (α = 0.05). Based on 103 single alveoli evaluated, the mean volume determined was 0.120 cm3 requiring a mean amount of graft material of 0.155 g. With only three exceptions, all parameters (volume, mass of augmentation material, density and homogeneity) correlated significantly (p < 0.020). The apical parts of the alveoli showed reduced density as compared to the middle parts (p < 0.001) and the homogeneity of the augmentation material was also lower as compared to the middle (p < 0.001) and cervical parts (p Collapse

Key Words

• alveolar ridge augmentation
• bone substitute materials
• ridge preservation

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Affiliation(s)

Samira Dahl
Virgilia Klär-Quarz
Annika Schulz
Matthias Karl
Tanja Grobecker-Karl Department of Prosthodontics, Saarland University, 66421 Homburg, Saar, Germany; (S.D.); (V.K.-Q.); (A.S.); (M.K.)

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A Narrative Review on the Effectiveness of Bone Regeneration Procedures with OsteoBiol® Collagenated Porcine Grafts: The Translational Research Experience over 20 Years

Over the years, several bone regeneration procedures have been proposed using natural (autografts, allografts, and xenografts) and synthetic (i.e., metals, ceramics, and polymers) bone grafts. In particular, numerous in vitro and human and animal in vivo studies have been focused on the discovery of innovative and suitable biomaterials for oral and maxillofacial applications in the treatment of severely atrophied jaws. On this basis, the main objective of the present narrative review was to investigate the efficacy of innovative collagenated porcine bone grafts (OsteoBiol^®, Tecnoss^®, Giaveno, Italy), designed to be as similar as possible to the autologous bone, in several bone regeneration procedures. The scientific publications were screened by means of electronic databases, such as PubMed, Scopus, and Embase, finally selecting only papers that dealt with bone substitutes and scaffolds for bone and soft tissue regeneration. A total of 201 papers have been detected, including in vitro, in vivo, and clinical studies. The effectiveness of over 20 years of translational research demonstrated that these specific porcine bone substitutes are safe and able to improve the biological response and the predictability of the regenerative protocols for the treatment of alveolar and maxillofacial defects.

Decellularized xenografts in regenerative medicine: From processing to clinical application

Decellularized xenografts are an inherent component of regenerative medicine. Their preserved structure, mechanical integrity and biofunctional composition have well established them in reparative medicine for a diverse range of clinical indications. Nonetheless, their performance is highly influenced by their source (ie species, age, tissue) and processing (ie decellularization, crosslinking, sterilization and preservation), which govern their final characteristics and determine their success or failure for a specific clinical target. In this review, we provide an overview of the different sources and processing methods used in decellularized xenografts fabrication and discuss their effect on the clinical performance of commercially available decellularized xenografts.

Structural and chemical features of xenograft bone substitutes: A systematic review of in vitro studies

Xenograft bone substitutes are obtained from different species and prepared by various procedures including heat treatment, hydrazine, and chemical and hydrothermal methods. These grafts are utilized widely because of similar structure and properties to human bone, proper bone formation, and biocompatibility. The aim of this systematic review was to evaluate different xenografts from structural and chemical aspects. In vitro studies published in English language, which assessed xenografts' features, met the inclusion criteria. Electronic search of four databases including PubMed, Google Scholar, Scopus, and Web of Science and a hand search until September 2020 were performed. The irrelevant studies were the ones which focused on cell adhesion and effect of growth factors. Finally, 25 studies were included in the review. Nineteen studies used bovine xenografts, and 12 studies applied heat treatment as their preparation method. Particles showed various morphologies, and their largest size was observed at 5 mm. From 18 studies, it is found that the smallest pore size was 1.3 µm and the highest pore size was 1000 µm. There is large heterogeneity of porosity, crystallinity, Ca/P ratio, and osteogenesis based on the preparation method. Proper porosity and the connection between pores affect bone regeneration. Therefore, biomaterial selection and outcomes evaluation should be interpreted separately.

Porcine Collagen-Bone Composite Induced Osteoblast Differentiation and Bone Regeneration In Vitro and In Vivo

Due to autogenous bone limitations, some substitute bone grafts were developed. Collagenated porcine graft (CPG) is able to regenerate new bone, although the number of studies is insufficient, highlighting the need for future studies to better understand the biomaterial. In order to understand better CPG′s possible dental guided bone regeneration indications, the aim of this work was to determine CPG′s biological capacity to induce osteoblast differentiation in vitro and guided bone regeneration in vivo, whilst being compared with commercial hydroxyapatite and beta tricalcium phosphate (HA/β-TCP) and porcine graft alone. Cell cytotoxicity (WST-1), alkaline phosphatase activity (ALP), and real-time polymerase chain reaction (qPCR) were assessed in vitro. Critical size defects of New Zealand white rabbits were used for the in vivo part, with critical size defect closures and histological analyses. WST-1 and ALP indicated that CPG directly stimulated a greater proliferation and confluency of cells with osteoblastic differentiation in vitro. Gene sequencing indicated stable bone formation markers, decreased resorption makers, and bone remodeling coupling factors, making the transition from osteoclast to osteoblast expression at the end of seven days. CPG resulted in the highest new bone regeneration by osteoconduction in critical size defects of rabbit calvaria at eight weeks. Nonetheless, all biomaterials achieved nearly complete calvaria defect closure. CPG was found to be osteoconductive, like porcine graft and HA/β-TCP, but with higher new bone formation in critical size defects of rabbit calvaria at eight weeks. CPG can be used for different dental guided bone regeneration procedures; however, further studies are necessary.

Histological Evaluation of a New Beta-Tricalcium Phosphate/Hydroxyapatite/Poly (1-Lactide-Co-Caprolactone) Composite Biomaterial in the Inflammatory Process and Repair of Critical Bone Defects

Background: The use of biomaterials is commonplace in dentistry for bone regeneration. The aim of this study was to evaluate the performance of a new alloplastic material for bone repair in critical defects and to evaluate the extent of the inflammatory process. Methods: Forty-five New Zealand rabbits were divided into five groups according to evaluation time (7, 14, 30, 60, 120 days), totaling 180 sites with six-millimeter diameter defects in their tibiae. The defects were filled with alloplastic material consisting of poly (lactide-co-caprolactone), beta-tricalcium phosphate, hydroxyapatite and nano-hydroxyapatite (BTPHP) in three different presentations: paste, block, and membrane. Comparisons were established with reference materials, such as Bio-ossTM, Bio-oss CollagenTM, and Bio-gideTM, respectively. The samples were HE-stained and evaluated for inflammatory infiltrate (scored for intensity from 0 to 3) and the presence of newly formed bone at the periphery of the defects. Results: Greater bone formation was observed for the alloplastic material and equivalent inflammatory intensity for both materials, regardless of evaluation time. At 30 days, part of the synthetic biomaterial, regardless of the presentation, was resorbed. Conclusions: We concluded that this novel alloplastic material showed osteoconductive potential, biocompatibility, low inflammatory response, and gradual resorption, thus an alternative strategy for guided bone regeneration.

Commercially available bone graft substitutes: the impact of origin and processing on graft functionality

Development of effective and cost-efficient bone tissue engineering grafts has been the key area of research for regenerative medicine, yet an ideal grafting material has remained elusive due in large part to the highly dynamic nature of bone. A wide array of materials, both natural and synthetic, have been implemented as potential candidates for commercially available products, yet the gold standard for grafting material still remains autogenous bone. We review currently commercially available bone graft materials and relevant graft characteristics that impact the effectiveness of tissue repair, emphasizing the advantages and disadvantages of materials based on composition and origin. Examined materials were selected through a web-based search for readily accessible and clinically applicable graft materials. Grafts were then categorized according to material source to examine advantages and disadvantages associated with allogenic, xenogeneic, synthetic materials. Lastly, the application of bioactive molecules onto these basal grafts is explored to illustrate the enhancement and regulative capacity of these additives on traditional osteobiologic materials.

Fabrication and Microstructure of Laminated HAP⁻45S5 Bioglass Ceramics by Spark Plasma Sintering

Hydroxyapatite (HAP) has excellent biocompatibility with living bone tissue and does not cause defensive body reactions, therefore, it has become one of the most widely used calcium phosphate materials in dental and medical fields. However, its poor mechanical properties have been a substantial challenge in the application of HAP for the replacement of load-bearing or large bone defects. Laminated HAP–45S5 bioglass ceramics composites were prepared by the spark plasma sintering (SPS) technique. The interface structures between the HAP and 45S5 bioglass layers and the mechanical properties of the laminated composites were investigated. It was demonstrated that there was mutual transfer and exchange of Ca and Na atoms at the interface between 45S5 bioglass/HAP laminated layers, which contributed considerably to the interfacial bonding. Due from the laminated structure and strong interface bonding, laminated HAP–45S5 bioglass is recommended for structural applications.

Synthesis and Application of Scaffolds of Chitosan-Graphene Oxide by the Freeze-Drying Method for Tissue Regeneration

Several biomaterials, including natural polymers, are used to increase cellular interactions as an effective way to treat bone injuries. Chitosan (CS) is one of the most studied biocompatible natural polymers. Graphene oxide (GO) is a carbon-based nanomaterial capable of imparting desired properties to the scaffolds. In the present study, CS and GO were used for scaffold preparation. CS was extracted from the mycelium of the fungus Aspergillus niger. On the other hand, GO was synthesized using an improved Hummers-Offemann method and was characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and dynamic light scattering (DLS). Subsequently, three formulations (GO 0%, 0.5%, and 1%) were used to prepare the scaffolds by the freeze-drying technique. The scaffolds were characterized by FTIR, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), to determine their thermal stability and pore size, demonstrating that their stability increased with the increase of GO amount. Finally, the scaffolds were implanted, recollected 30 days later, and studied with an optical microscope, which evidenced the recovery of the tissue architecture and excellent biocompatibility. Hence, these results strongly suggested the inherent nature of chitosan/graphene oxide (CS/GO) scaffolds for their application in bone tissue regeneration.

Immunohistochemical evaluation after Sr-enriched biphasic ceramic implantation in rabbits femoral neck: comparison of seven different bone conditions

Strontium (Sr) has shown effectiveness for stimulating bone remodeling. Nevertheless, the exact therapeutic values are not established yet. Authors hypothesized that local application of Sr-enriched ceramics would enhance bone remodeling in constant osteoporosis of rabbits' femoral neck bone. Seven different bone conditions were analyzed: ten healthy rabbits composed a control group, while other twenty underwent ovariectomy and were divided into three groups. Bone defect was filled with hydroxyapatite 30% (HAP) and tricalcium phosphate 70% (TCP) granules in 7 rabbits, 5% of Sr-enriched HAP/TCP granules in 7, but sham defect was left unfilled in 6 rabbits. Bone samples were obtained from operated and non-operated legs 12 weeks after surgery and analyzed by histomorphometry and immunohistochemistry (IMH). Mean trabecular bone area in control group was 0.393 mm2, in HAP/TCP - 0.226 mm2, in HAP/TCP/Sr - 0.234 mm2 and after sham surgery - 0.242 mm2. IMH revealed that HAP/TCP/Sr induced most noticeable increase of nuclear factor kappa beta 105 (NFkB 105), osteoprotegerin (OPG), osteocalcin (OC), bone morphogenetic protein 2/4 (BMP 2/4), collagen type 1α (COL-1α), interleukin 1 (IL-1) with comparison to intact leg; NFkB 105 and OPG rather than pure HAP/TCP or sham bone. We concluded that Sr-enriched biomaterials induce higher potential to improve bone regeneration than pure bioceramics in constant osteoporosis of femoral neck bone. Further studies on bigger osteoporotic animals using Sr-substituted orthopedic implants for femoral neck fixation should be performed to confirm valuable role in local treatment of osteoporotic femoral neck fractures in humans.

Facial Bone Reconstruction Using both Marine or Non-Marine Bone Substitutes: Evaluation of Current Outcomes in a Systematic Literature Review

The aim of the present investigation was to systematically analyse the literature on the facial bone reconstruction defect using marine collagen or not and to evaluate a predictable treatment for their clinical management. The revision has been performed by searched MEDLINE and EMBASE databases from 2007 to 2017. Clinical trials and animal in vitro studies that had reported the application of bone substitutes or not for bone reconstruction defect and using marine collagen or other bone substitute material were recorded following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The first selection involved 1201 citations. After screening and evaluation of suitability, 39 articles were added at the revision process. Numerous discrepancies among the papers about bone defects morphology, surgical protocols, and selection of biomaterials were found. All selected manuscripts considered the final clinical success after the facial bone reconstruction applying bone substitutes. However, the scientific evidence regarding the vantage of the appliance of a biomaterial versus autologous bone still remains debated. Marine collagen seems to favor the dimensional stability of the graft and it could be an excellent carrier for growth factors.

[The prospects of hydrogels usage as a basis for curable osteoplastic materials]

The article deals with the main types of the polymers used in hydrogel preparation. Their biological, physical and chemical properties was compared. Ways of polymers hardening and prospects of medical application were considered. The prospect of use of chitosan hydrogels activated by osteoinductors as a material for bone augmentation were concluded.

Comparison of Two Xenograft Materials Used in Sinus Lift Procedures: Material Characterization and In Vivo Behavior

Detailed information about graft material characteristic is crucial to evaluate their clinical outcomes. The present study evaluates the physico-chemical characteristics of two xenografts manufactured on an industrial scale deproteinized at different temperatures (non-sintered and sintered) in accordance with a protocol previously used in sinus lift procedures. It compares how the physico-chemical properties influence the material’s performance in vivo by a histomorphometric study in retrieved bone biopsies following maxillary sinus augmentation in 10 clinical cases. An X-ray diffraction analysis revealed the typical structure of hydroxyapatite (HA) for both materials. Both xenografts were porous and exhibited intraparticle pores. Strong differences were observed in terms of porosity, crystallinity, and calcium/phosphate. Histomorphometric measurements on the bone biopsies showed statistically significant differences. The physic-chemical assessment of both xenografts, made in accordance with the protocol developed on an industrial scale, confirmed that these products present excellent biocompatibilitity, with similar characteristics to natural bone. The sintered HA xenografts exhibited greater osteoconductivity, but were not completely resorbable (30.80 ± 0.88% residual material). The non-sintered HA xenografts induced about 25.92 ± 1.61% of new bone and a high level of degradation after six months of implantation. Differences in the physico-chemical characteristics found between the two HA xenografts determined a different behavior for this material.

Dexmedetomidine Analgesia Effects in Patients Undergoing Dental Implant Surgery and Its Impact on Postoperative Inflammatory and Oxidative Stress

The aim of the study was to determine whether or not dexmedetomidine- (DEX-) based intravenous infusion in dental implantation can provide better sedation and postoperative analgesia via suppressing postoperative inflammation and oxidative stress. Sixty patients were randomly assigned to receive either DEX (group D) or midazolam (group M). Recorded variables were vital sign (SBP/HR/RPP/SpO2/RR), visual analogue scale (VAS) pain scores, and observer's assessment of alertness/sedation scale (OAAS) scores. The plasma levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), antioxidant superoxide dismutase (SOD), and the lipid peroxidation product malondialdehyde (MDA) were detected at baseline and after 2, 4, and 24 h of drug administration. The VAS pain scores and OAAS scores were significantly lower for patients in group D compared to group M. The plasma levels of TNF-α, IL-6, and MDA were significantly lower in group D patients than those in group M at 2 h and 4 h. In group M, SOD levels decreased as compared to group D at 2 h and 4 h. The plasma levels of TNF-α, IL-6, and MDA were positively correlated with VAS pain scores while SOD negatively correlated with VAS pain scores. Therefore, DEX appears to provide better sedation during office-based artificial tooth implantation. DEX offers better postoperative analgesia via anti-inflammatory and antioxidation pathway.

Evaluation of polyvinyl alcohol composite membranes containing collagen and bone particles

Composite biomaterials provide alternative materials that improve on the properties of the individual components and can be used to replace or restore damaged or diseased tissues. Typically, a composite biomaterial consists of a matrix, often a polymer, with one or more fillers that can be made up of particles, sheets or fibres. The polymer matrix can be chosen from a wide range of compositions and can be fabricated easily and rapidly into complex shapes and structures. In the present study we have examined three size fractions of collagen-containing particles embedded at up to 60% w/w in a poly(vinyl alcohol) (PVA) matrix. The particles used were bone particles, which are a mineral-collagen composite and demineralised bone, which gives naturally cross-linked collagen particles. SEM showed well dispersed particles in the PVA matrix for all concentrations and sizes of particles, with FTIR suggesting collagen to PVA hydrogen bonding. Tg of membranes shifted to a slightly lower temperature with increasing collagen content, along with a minor amount of melting point depression. The modulus and tensile strength of membranes were improved with the addition of both particles up to 10 wt%, and were clearly strengthened by the addition, although this effect decreased with higher collagen loadings. Elongation at break decreased with collagen content. Cell adhesion to the membranes was observed associated with the collagen particles, indicating a lack of cytotoxicity.