Abdullah C. Akman

Effects of Platelet-Rich Plasma and Chitosan Combination on Bone Regeneration in Experimental Rabbit Cranial Defects

This study aimed to investigate and compare the effect of chitosan sponge and platelet-rich plasma (PRP) gel alone as well as their combination on bone regeneration in rabbit cranial defects. Four cranial defects with a 4.5-mm diameter were created in rabbit cranium and grafted with PRP, chitosan sponge alone, and chitosan sponge incorporated with PRP. The rabbits were killed by the fourth and eighth weeks, and the defects were analyzed histologically. Higher bone formation was observed in the PRP group when compared with the other groups at weeks 4 and 8. All parts of the defects were filled with thick trabecular new bone in the PRP group. The amount of new bone formation in the control groups was found to be less when compared with the PRP group and the least in the chitosan group. The defects that were filled with chitosan sponge showed a limited amount of new bone formation and an obvious fibrous demarcation line between chitosan particles and bone. Application of PRP showed a histological tendency toward increased bone formation. Other forms or derivatives of chitosan may have beneficial effects to achieve new bone regeneration.

bFGF-loaded HA-chitosan: A promising scaffold for periodontal tissue engineering

A scaffold containing growth factors promoting regeneration may be a useful device to maintain periodontal regeneration when applied with appropriate cells. The aim of this study is to evaluate the convenience of chitosan and hydroxyapatite (HA)-chitosan scaffolds loaded with basic fibroblast growth factor (bFGF) for periodontal tissue engineering applications. Scaffolds were fabricated by freeze-drying technique using 2 and 3% chitosan gel in the absence or presence of HA particles. Addition of HA beads to chitosan gels produced a novel scaffold in which the pore sizes and interconnectivity were preserved. The scaffolds were loaded with 100 ng bFGF by embedding technique. HA-chitosan scaffolds provide better controlled release kinetics for bFGF compared with chitosan scaffolds and total release continued up to 168 h. Cell culture studies were carried out with periodontal ligament (PDL) cells and cementoblasts. Both 3-[4,5-dimethylthiazol-2-yl]-diphenyltetrazolium bromide (MTT) assay and confocal laser scanning microscope analysis revealed cells proliferating inside the scaffolds. The results demonstrated that bFGF-loaded HA-chitosan scaffolds provide a suitable three-dimensional environment supporting the cellular structure, proliferation, and mineralization.

Bone Morphogenetic Protein-6-loaded Chitosan Scaffolds Enhance the Osteoblastic Characteristics of MC3T3-E1 Cells

The purpose of this study is to investigate the convenience of bone morphogenetic protein-6 (BMP-6)-loaded chitosan scaffolds with preosteoblastic cells for bone tissue engineering. MC3T3-E1 cells were seeded into three different groups: chitosan scaffolds, BMP-6-loaded chitosan scaffolds, and chitosan scaffolds with free BMP-6 in culture medium. Tissue-engineered constructs were characterized by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazoliumbromide assay, scanning electron microscopy (SEM), mineralization assay (von Kossa), alkaline phosphatase (ALP) activity, and osteocalcin (OCN) assays. BMP-6-loaded chitosan scaffolds supported proliferation of the MC3T3-E1 mouse osteogenic cells in a similar pattern as the unloaded chitosan scaffolds group and as the chitosan scaffolds with free BMP-6 group. SEM images of the cell-seeded scaffolds revealed significant acceleration of extracellular matrix synthesis in BMP-6-loaded chitosan scaffolds. Both levels of ALP and OCN were higher in BMP-6-loaded chitosan scaffold group compared with the other two groups. In addition, BMP-6-loaded scaffolds showed strong staining in mineralization assays. These findings suggest that BMP-6-loaded chitosan scaffold supports cellular functions of the osteoblastic cells; therefore, this scaffold is considered as a new promising vehicle for bone tissue engineering applications.

Effect of inflammation on cytokine levels and bone remodelling markers in peri-implant sulcus fluid: a preliminary report.

OBJECTIVES Since ingredients of peri-implant sulcus fluid (PISF) may be related to the bony structure surrounding dental implants, analyze of specific markers related to bone resorption in PISF seems to be suitable for long term monitoring of peri-implant health. It is suggested that analysis of PISF may serve for detection of inflammation. The aim of this study is to analyze PISF interleukin-1 beta (IL-1β), IL-10, osteoprotegerin (OPG), receptor activator of nuclear factor-kappa B ligand (RANKL) levels to determine whether the diagnostic value of PISF can be used to evaluate early changes around implants. MATERIALS AND METHODS A total of 47 dental implants either healthy/non-inflamed (n=20) (Group I), or gingivitis/inflamed (n=27) (Group II), were classified. Peri-implant status has been evaluated by clinical evaluation (plaque index, gingival index, probing depth and gingival bleeding time index) were recorded and PISF samples were also obtained. PISF IL-1β, IL-10, RANKL, and OPG levels were measured by enzyme-linked immunosorbent assay. Potential volumetric changes in PISF were also evaluated. RESULTS All clinical parameters and volume of PISF were higher in Group II and these differences were statistically significant except volume values. IL-1β, IL-10 and OPG levels in PISF were significantly higher in Group II. Although the PISF RANKL level in Group II was higher than the level of Group I, the difference between groups did not reach the statistically significant level. CONCLUSIONS These data suggest that a balance of inflammatory- and osteoclastogenesis related molecules locally produced may play an important role in the development of inflammatory peri-implant lesions.

In Vitro Release of Dexamethasone or bFGF from Chitosan/Hydroxyapatite Scaffolds

Chitosan scaffolds containing dexamethasone (Dex) or basic fibroblast growth factor (bFGF) were developed to create alternative drug-delivery systems for possible tissue-engineering applications such as periodontal bone regeneration. Chitosan solutions (2% and 3% (w/v) in acetic acid) were prepared from chitosan flakes with high deacetylation degree (>85%), then these solutions were freeze-dried at –80°C to obtain scaffolds with interconnected pore structures. Dex and bFGF were incorporated into scaffolds by embedding method (solvent sorption method). The initial loading amounts were varied as 300, 600 and 900 ng Dex per dry scaffold (average dry weight is 3 mg) and 50 or 100 ng bFGF per dry scaffold to a range of deliverable doses. Release studies which were conducted in Dulbeccos phosphate-buffered saline (DPBS) showed that 900 ng Dex loaded chitosan scaffolds in both compositions released total Dex during a 5-day period at a nearly constant rate after the initial burst. However, bFGF release from all scaffolds with both loading amounts (50 ng or 100 ng) was completed in 10 or 20 h. In order to prolong the release period of bFGF, composite scaffolds were fabricated in the presence of hydroxyapatite (HA) beads with average particle size of 40 μm. Sustained release of bFGF up to 7 days was achieved due to the electrostatic interactions between HA and bFGF molecules. These results suggested that chitosan scaffolds can be suitable for Dex release; however, the presence of HA in the chitosan scaffold is necessary to achieve the desired release period for bFGF.

ABM/P-15 modulates proliferation and mRNA synthesis of growth factors of periodontal ligament cells.

Objective. Periodontal regeneration is histologically defined as regeneration of the tooth supporting structures, including alveolar bone, periodontal ligament, and cementum. Cells in the remaining periodontal tissues need optimal conditions if they are to perform their functions in the regeneration process. The present study is an investigation of the molecular effects of ABM/P-15 on human periodontal ligament cells (PDL) in vitro. Material and methods. PDL cells obtained from healthy subjects were used for in vitro experiments. Cell proliferation, morphology, and mineralization using Von kossa staining were evaluated. mRNA expressions for transforming growth factor-β (TGF-β), insulin-like growth factor-I (IGF-I), basic fibroblast growth factor (b-FGF), vascular endothelial growth factor (VEGF), bone morphogenic protein-2 (BMP-2), platelet-derived growth factor (PDGF), and type 1 collagen (COL1) were assessed on days 3 and 7 using RT-PCR. Results. ABM/P-15 enhanced proliferation of cultured PDL cells. It increased the mRNA expression of TGF-β and BMP-2 in cultured PDL cells on days 3 and 7. IGF-I and b-FGF mRNA expressions showed a slight decrease, while PDGF expression was observed to have increased on day 3. VEGF and COL1 mRNA expressions were found not to be different on days 3 and 7. No differences were observed in the mineralization properties of cultured PDL cells treated with or without ABM/P-15. Conclusions. Based on the results of this in vitro study, it may be concluded that ABM/P-15 enhanced the regenerative capacity of PDL by regulating specific gene expressions of cells during early wound healing.

SEQUENTIAL IGF-1 AND BMP-6 RELEASING CHITOSAN/ALGINATE/PLGA HYBRID SCAFFOLDS FOR PERIODONTAL REGENERATION

The goal of periodontal tissue engineering is to repair or regenerate the destructed or lost periodontium by improving functions of cells in the remaining tissue. For continuty of cell growth process, two group of growth factors, i.e. competence factors and progression factors, are needed to act together. However, the short biological half-life of these factors limits their effects on cells and their clinical efficacy. The purpose of this study is to develop different microparticles-loaded chitosan carriers/scaffolds for controlled and sequential delivery of a competence factor, insulin-like growth factor (IGF-1), and progression factor, bone morphogenetic factor-6 (BMP-6). Alginate and poly (lactic-co-glycolic acid) (PLGA) microparticles provided release of IGF-1 and BMP-6 for early short period and for long period, respectively. The cell culture studies showed that, chitosan/alginate/PLGA hybrid scaffolds induced proliferation and osteoblastic differentiation of cementoblasts when compared with IGF-1 and BMP-6 free chitosan scaffold.

Increased cancer risk in patients with periodontitis

Abstract Background: Previous studies have noted a possible association between periodontal diseases and the risk of various cancers. We assessed cancer risk in a cohort of patients with moderate to severe periodontitis. Methods: Patients diagnosed with moderate to severe periodontitis by a periodontist between 2001 and 2010 were identified from the hospital registry. Patients younger than 35 years of age or with a prior cancer diagnosis were excluded. The age- and gender-standardized incidence rates (SIR) were calculated by dividing the number of observed cases by the number of expected cases from Turkish National Cancer Registry 2013 data. Results: A total of 280 patients were included (median age 49.6, 54% female). Median follow-up was 12 years. Twenty-five new cancer cases were observed. Patients with periodontitis had 77% increased risk of cancer (SIR 1.77, 95% CI 1.17–2.58, p = .004). Women with periodontitis had significantly higher risk of breast cancer (SIR 2.40, 95% CI 0.88–5.33) and men with periodontitis had significantly higher risk of prostate cancer (SIR 3.75, 95% CI 0.95–10.21) and hematological cancers (SIR 6.97, 95% CI 1.77–18.98). Conclusion: Although showing a causal association necessitates further investigation, our results support the idea that periodontitis might be associated with increased cancer risk, particularly with hematological, breast and prostate cancers.

Evaluation of gingival crevicular fluid and peri-implant crevicular fluid levels of sclerostin, TWEAK, RANKL and OPG

Background: The combination of local and systemic factors play role in the pathogenesis of periodontal and peri‐implant diseases. Host‐derived enzymes, cytokines and other proinflammatory mediators play an integral role in this destruction. The aim of this study is to evaluate gingival crevicular fluid (GCF) and peri‐implant crevicular (PICF) fluid levels of sclerostin, TNF‐related weak inducer of apoptosis (TWEAK), receptor activator of nuclear factor kappa‐beta ligand (RANKL) and osteoprotegerin OPG in periodontal and peri‐implant tissues in disease and health conditions and also to assess the potential for use as biomarkers. Materials and methods: The study population was consisted of 50 women and 41 men, in the total of 91 individuals, with a mean age of 51.84 ± 14.05. Periodontitis (n = 22), periodontal health (n = 17), peri‐implantitis (n = 27) and peri‐implant health (n = 25) groups were established according to clinical and radiographic examination results of 39 teeth and 52 implants restored with fixed prosthetic restorations. In all groups, periodontal and peri‐implant parameters (probing depth, gingival recession, gingival bleeding time index, gingival index, and plaque index) were recorded and GCF and PICF samples were also collected. Sclerostin, TWEAK, RANKL and OPG levels in GCF and PICF were measured with ELISA tests. Results: Peri‐implantitis group presented significantly higher levels of Sclerostin (p = 0.002), TWEAK(p < 0.0001), RANKL(p < 0.0001), and OPG (p = 0.037) compared to peri‐implant health group. Similarly, significantly higher levels of TWEAK (p = 0.001), RANKL(p < 0.0001), and OPG(p = 0.025) were detected in periodontitis group when compared to periodontal health group. Statistically significant correlations were also noted between biochemical parameters and clinical parameters. Conclusion: Findings of this study evaluating four different bone metabolism related proteins at the same time, suggests levels of sclerostin may be a biomarker for peri‐implant disease presenting significantly higher levels in the peri‐implantitis group than in the peri‐implant health group. Moreover, levels of TWEAK can be a good indicator for both periodontal and peri‐implant disease, due to the correlations with periodontal clinical parameters and the higher levels of TWEAK in diseased sites compared to the healthy sites for both dental implants and teeth.

Tissue engineering applications and nanobiomaterials in periodontology and implant dentistry

Abstract The treatment of periodontal diseases with their associated anomalies and replacement of lost teeth by endosseous dental implants sometimes undertakes a stringent process with high variations in success rates and predictability of regeneration. An applied biomedical research area, tissue engineering, aims to develop biomaterials or procedures for replacing damaged tissues with new ones by adhering to the principles of developmental biology, biomaterials science and cell biology. Nanotechnology came out as a new scientific discipline in 1990s and with significant developments on techniques and materials, various treatment strategies have been defined and functional tissue regeneration have become a reality. Today, an elaborated oral health care achievement is now beyond the expectance by the utilization of tissue engineering modalities and nanobiomaterials. This chapter aims to highlight and discuss the role of nanobiomaterials and their diagnostic, therapeutic and preventive potential in periodontics and implants dentistry, with particular emphasis given to current challenges and future possibilities related with the strategies of tissue engineering in periodontology and implant dentistry.