Performance of a multiphase bioactive socket plug with a barrier function for alveolar ridge preservation.

The natural healing process of extraction socket and traditional socket plug material could not prevent buccal bone wall resorption and down growth of epithelium from the socket orifice. A multiphase bioactive socket plug (BP) is designed to overcome the natural healing process by maintaining the three-dimensional (3D) volume of extraction sockets, particularly in sockets with wall defects, and later provide sufficient alveolar bone volume for implant placement. The study aimed to fabricate and evaluate the physical, chemical, and biological performance of BPin vitro. The BP was fabricated through freeze-drying and layer-by-layer assembly, comprised of a base serving as a scaffold, a central portion for promoting bone regeneration, an upper buccal portion for maintaining alveolar socket dimension with a covering collagen membrane (Memb) on the top and upper buccal surface to prevent soft tissue infiltration. The BP as the experimental group and a pure collagen plug (CP) as the control group were investigated and compared. Radiograph, scanning electron microscopy, and energy-dispersive spectroscopy mapping confirmed that the four-part BP was successfully assembled and fabricated. Swelling rate analysis indicated that BP, CP, and Memb reached swelling equilibrium within 1 hour. BP exhibited a high remaining weight percentage in collagenase solution (68.81 ± 2.21% on day 90) and sustained calcium ion release, reaching the maximum 0.13 ± 0.04 mmol l-1on day 14. In biological assays, BP exhibited excellent cell proliferation (The OD value increased from 0.02 on day 1 to 0.23 on day 21.). The BP group exhibited higher alkaline phosphatase activity and osteocalcin content than the CP group within 21 days. Memb and BP exhibited outstanding barrier function, as evidenced by Hematoxylin and eosin staining. In summary, the multiphase bioactive socket plug represents a promising scaffold for alveolar ridge preservation application.

Fabrication and characterization of a bioactive composite scaffold based on polymeric collagen/gelatin/nano ß-TCP for alveolar bone regeneration.

One strategy to correct alveolar bone defects is use of bioactive bone substitutes to maintain the structure of defect site and facilitate cells and vessels' ingrowth. This study aimed to fabricate and characterize the freeze-dried bone regeneration scaffolds composed of polymeric Type I collagen, nano Beta-tricalcium phosphate (ß-TCP), and gelatin. The stable structures of scaffolds were obtained by thermal crosslinking and EDC/NHS ((1-ethyl-3-(3-dimethylaminopropyl) carbodiimide)/(N-hydroxysuccinimide)) chemical crosslinking processes. Subsequently, the physicochemical and biological properties of the scaffolds were characterized and assessed. The results indicated the bioactive composite scaffolds containing 10% and 20% (w/v) nano ß-TCP exhibited suitable porosity (84.45 ± 25.43 nm, and 94.51 ± 14.69 nm respectively), a rapid swelling property (reaching the maximum swelling rate at 1 h), excellent degradation resistance (residual mass percentage of scaffolds higher than 80% on day 90 in PBS and Type I collagenase solution respectively), and sustained calcium release capabilities. Moreover, they displayed outstanding biological properties, including superior cell viability, cell adhesion, and cell proliferation. Additionally, the scaffolds containing 10% and 20% (w/v) nano ß-TCP could promote the osteogenic differentiation of MC3T3-E1. Therefore, the bioactive composite scaffolds containing 10% and 20% (w/v) nano ß-TCP could be further studied for being used to treat alveolar bone defects in vivo.

Effects of Oral Cavity Stem Cell Sources and Serum-Free Cell Culture on Hydrogel Encapsulation of Mesenchymal Stem Cells for Bone Regeneration: An In Vitro Investigation.

INTRODUCTION: To develop a stem cell delivery model and improve the safety of stem cell transplantation for bone regeneration, this study aimed to determine the effects of stem cell sources, serum-free cell culture, and hydrogel cell encapsulation on the growth and osteogenic differentiation of mesenchymal stem cells (MSCs) from the oral cavity. METHODS: The study groups were categorized according to stem cell sources into buccal fat pad adipose (hBFP-ADSCs) (Groups 1, 4, and 7), periodontal ligament (hPDLSCs) (Groups 2, 5, and 8), and dental pulp-derived stem cells (hDPSCs) (Groups 3, 6, and 9). MSCs from each source were isolated and expanded in three types of sera: fetal bovine serum (FBS) (Groups 1-3), human serum (HS) (Groups 4-6), and synthetic serum (SS) (StemPro™ MSC SFM) (Groups 7-9) for monolayer (m) and hydrogel cell encapsulation cultures (e). Following this, the morphology, expression of MSC cell surface antigens, growth, and osteogenic differentiation potential of the MSCs, and the expression of adhesion molecules were analyzed and compared. RESULTS: SS decreased variations in the morphology and expression levels of cell surface antigens of MSCs from three cell sources (Groups 7m-9m). The levels of osteoblastic differentiation of the hPDLSCs and hBFP-ADSCs were increased in SS (Groups 8m and 7m) and the cell encapsulation model (Groups 1e, 4e, 7e-9e), but the promoting effects of SS were decreased in a cell encapsulation model (Groups 7e-9e). The expression levels of the alpha v beta 3 (ITG-αVß3) and beta 1 (ITG-ß1) integrins in the encapsulated cells in FBS (Group 1e) were higher than those in the SS (Group 7e). CONCLUSIONS: Human PDLSCs and BFP-ADSCs were the optimum stem cell source for stem cell encapsulation by using nanohydroxyapatite-calcium carbonate microcapsule-chitosan/collagen hydrogel in serum-free conditions.

The efficacy of a semi-resorbable membrane based on silk fibroin-Glycerol on bone regeneration in rabbit calvarial defects compared to a commercial collagen membrane.

Silk fibroin-glycerol-based membranes were fabricated and characterized for use as a self-maintaining and non-collapsible semi-resorbable membrane in guided bone regeneration. The study assessed the bone regeneration capacity of silk fibroin-glycerol-based membranes compared to a collagen membrane in 10-mm circular bilateral calvarial defects of 20 male New Zealand white rabbits. The animals were divided into two sets of time frames of 4 and 12 weeks and allocated into four groups (n = 5/group); an empty defect (E), a collagen membrane (Bio-Gide®; BG), a silk fibroin-glycerol-collagen membrane (SGC), and a silk fibroin-glycerol membrane (SG). The bone density (optical density, OD) from the 2D radiographs, tissue reaction from histological sections, new bone volume, and area from micro-CT and the histomorphometry were evaluated. The Mean OD of the E (34.49 ± 14.21%) and BG groups (35.71 ± 9.65%) at 12 weeks were higher than at 4 weeks, but the SGC (39.04 ± 7.94%) and SG (40.96 ± 9.25%) groups were lower at 4 weeks. The new bone volumes at 4 weeks of the SG (24.19 ± 1.35%) and SGC groups (24.19 ± 3.47%) were significantly higher than the BG group (16.93 ± 2.95%) but were not different from the E group (18.39±4.78%). At 12 weeks, the new bone volumes in the SGC (29.09 ± 3.81%), SG (29.11 ± 5.94%), and BG groups (26.26 ± 4.42%) were higher than in the E group (21.63 ± 5.81%) without statistical significance. Histological images in the SGC and SG groups showed slow biodegradation without a foreign body reaction. The new bone area at 4 weeks was lowest in BG (12.95 ± 5.44%), and the others were comparable. At 12 weeks, the new bone area in the E group (23.55±8.69%) was lower than the BG (31.42 ± 6.18%), SG (35.25 ± 13.92%), and SGC groups (36.35 ± 10.23%). Silk fibroin-glycerol-based membranes are semi-resorbable membranes that possess a self-maintaining property, have a barrier function without collapsing, and are successful in facilitating bone regeneration.

In Vitro Biocompatibility of a Novel Semi-Rigid Shell Barrier System: As a New Application for Guided Bone Regeneration.

This study evaluated the in vitro biocompatibility of a novel, semi-rigid shell barrier system for guided bone regeneration (GBR) based on polycaprolactone and biphasic calcium phosphate membranes and consisting of a semi-rigid shell (SR) and two semi-resorbable barrier membranes, i.e., a buffered (BF) and an airdried (AD) membrane. In vitro biocompatibility, cell cytotoxicity, cell proliferation and differentiation were evaluated with osteoblast (MC3T3-E1) and fibroblast (L929) cells compared to the d-PTFE membrane (Cytoplast®, CP). The osteoblasts and fibroblasts were well attached and proliferated on all materials from days 1, 3, and 7 without cell cytotoxicity. All groups showed that osteoblast and fibroblast cell proliferation increased from day 1 to day 14-17 and decreased on day 21. On day 21, the CP membrane presented significantly higher osteoblast cell numbers than the BF membrane and the SR shell (p = 0.000). The CP membrane presented a significantly higher amount of fibroblast cells than the other groups (p = 0.000). The SR shell and the BF membrane demonstrated higher osteoblast cell differentiation markers including ALP activity, osteocalcin, and mineral secretion than the CP and the AD membrane. The semi-rigid shell barrier system demonstrated good in vitro biocompatibility and supported osteogenic cell proliferation and differentiation better than the d-PTFE membrane.

Fabrication and characterization of a semi-rigid shell barrier system made of polycaprolactone and biphasic calcium phosphate: A novel barrier system for bone regeneration.

INTRODUCTION: Nowadays, no barrier membrane serves all purposes of bone augmentation. This study aimed to fabricate a semi-rigid shell barrier system composed of a semi-rigid shell and a covering membrane or a semi-resorbable barrier membrane, based on polycaprolactone (PCL) and biphasic calcium phosphate (BCP) for guided bone regeneration (GBR). MATERIALS AND METHODS: A shell and a covering membrane were fabricated by a solvent casting technique based on PCL (70) and BCP (30). The experimental groups were a semi-rigid shell, an airdried membrane, a buffered membrane, and a commercial d-PTFE as a control. Physico-chemical, mechanical properties, and in vitro biocompatibility with osteoblasts and fibroblasts cells were evaluated in all groups. RESULTS: The fabricated materials had rough surfaces with a homogeneous distribution of BCP particles on one side and a smooth surface on the opposite side. The airdried membrane presented a rougher surface on both top and bottom sides (Sq = 605.45 nm, 556.82 nm) than the semi-rigid shell (310.74 nm, 424.56 nm) and the buffered membrane (277.9 nm, 306.98 nm), respectively. The pore sizes of the airdried membrane (25-40 µm) were larger than the semi-rigid shell (5-40 µm) and the buffered membrane (5-25 µm). The porosities of the airdried and buffered membranes (∼40%) were higher than the semi-rigid shell (∼20%) significantly (p < 0.05). All fabricated materials were hydrophilic, with the lowest water contact angle in the semi-rigid shell (54.7° ± 3.06°), then the airdried (61.15° ± 4.76°), and the buffered (75.74° ± 2.8°) respectively. The semi-rigid shell resisted a higher load on compressive force (18.82 ± 2.72 N) than the d-PTFE membrane (4.23 ± 0.5 N). The tensile stress of the buffered membrane (2.544 ± 0.19 MPa) was not different from the d-PTFE (2.908 ± 0.12 MPa) but was higher than the airdried membrane (1.302 ± 0.13 MPa) significantly (P < 0.05). The airdried membrane had reached 100% swelling ability within 1 h, which was significantly faster than the buffered membrane (12 h) and the semi-rigid shell (7 days), and they were slowly degraded by lysozyme at 6 months (airdried: 24.88% ± 0.96%, buffered: 13.67% ± 0.55%, and semi-rigid: 8.62% ± 0.88%). All fabricated membranes showed no toxicity to osteoblast and fibroblast cells. CONCLUSION: The semi-rigid shell and the covering membranes demonstrated suitable physical and mechanical properties, and biocompatibility, and can be assembled as the novel semi-rigid shell barrier system for bone regeneration.

Physical and biological performances of a semi-resorbable barrier membrane based on silk fibroin-glycerol-fish collagen material for guided bone regeneration.

The fragility of silk fibroin film is a drawback to being used as a barrier membrane. Semi-resorbable barrier membranes maintain function longer than a resorbable membrane and no need to be removed. The study aimed to fabricate semi-resorbable membranes using silk fibroin with glycerol plasticizer (Group A), immobilized with fish collagen (Group B), and then characterized, in vitro biocompatibility tested, and compared with a commercial collagen membrane (Group C). Group B showed more roughness (0.2155 µm) than Group A (0.1424 µm). Group A was more hydrophilic (76.75° ± 3.07°) and more stiffness (28.93% ± 15.56%) than Group B (112.67° ± 1.94°, 42.10% ± 11.46%) and C (54.79% ± 13.44%) without significant difference. Group C had a significantly higher (p < 0.05) swelling degree and less degradation rate than others. Group A showed significantly highest (p < 0.05) cell proliferation. Group C showed more alkaline phosphatase activity than others but no significant difference in osteocalcin and Alizarin Red activity on day 21. The semi-resorbable membrane based on silk fibroin-glycerol possessed good physical and mechanical properties, and well-supported osteoblastic cell proliferation and differentiation.

Osseointegrated membranes based on electro-spun TiO2/hydroxyapatite/polyurethane for oral maxillofacial surgery.

Membranes which have an osseointegration abilty are often selected as biomaterials in oral and maxillofacial surgery. Although these membranes are often the best option for certain uses, it is a challenge to create functionally attractive membranes. In this research, electro-spun titanium oxide (TiO2)/hydroxyapatite (HA)/polyurethane (PU) membranes were fabricated with different ratios of HA and TiO2: 100: 0, 70:30, 50:50, 30:70 and 0:100 w/w. The morphologies of the different mixtures were assessed with a Scanning Electron Microscope (SEM) and Field Emission Microscope (FESEM). Element analysis was performed with EDX. The physical properties of the water contact angles and mechanical strength were tested and the membranes cultured with osteoblasts to evaluate their biological functions, cell adhesion, viability, proliferation, alkaline phosphatase (ALP) activity, and calcium content. The results showed that the membranes with TiO2 and HA had smaller fibers than those without TiO2 and HA. The TiO2- and HA-including compounds showed the formation of particle aggregation on the surface of the fibers. They also had higher water contact angles, mechanical strength, and stiffness than those without TiO2 and HA, and they had better cell adhesion, viability, proliferation, ALP activity and calcium content. The membrane with a 50:50 TiO2:HA ratio had more unique biological functions than the others. Finally, our research demonstrated that osseointegrated membranes with 50:50 TiO2:HA are promising for oral and maxillofacial surgery.

Layer-by-layer electrospun membranes of polyurethane/silk fibroin based on mimicking of oral soft tissue for guided bone regeneration.

Guided bone regeneration is an effective method that can enhance bone volume at a defect site of the mandible before material implantation. Layer-by-layer electrospun membranes of polyurethane/silk fibroin (SF) were fabricated to mimic oral soft tissue. The electrospun polyurethane fibers were initially fabricated into a membrane. Next, the polyurethane layer was covered with electrospun SF fibers at different thicknesses. Then, the SF layer was covered with electrospun polyurethane fibers. Afterward, the morphologies of the membranes were observed and analyzed by scanning electron microscopy. The physical properties of the membranes were evaluated from the contact angle and mechanical properties. The biological performances were evaluated by observing cell adhesion, viability and proliferation, alkaline phosphatase activity, and calcium content. The results demonstrated that the membrane with a thin SF core showed better physical properties and mechanical performance than the thicker SF cores. Finally, the results deduced that the membrane with a thin SF core was promising for guided bone regeneration.

Allogenic human serum, a clinical grade serum supplement for promoting human periodontal ligament stem cell expansion.

Exposing human periodontal ligament stem cells (hPDLSCs) to animal proteins during cell expansion would compromise quality and safety of the hPDLSCs for clinical applications. The current study aimed to evaluate the replacement of animal-based serum by human serum for the expansion of hPDLSCs. hPDLSCs were cultured in culture media supplemented with four types of serums: Group A: fetal bovine serum (FBS); Group B: allogeneic human male AB serum (HS); Group C: in-house autologous (Auto-HS); and Group D: in-house allogeneic human serums (Allo-HS). Exhibitions of mesenchymal stem cell characteristics of hPDLSCs were examined. Then, growth and osteogenic (OS) differentiation potential of hPDLSCs in FBS and HS at passages 5 and 15 were compared to investigate the effects of serum supplements on growth and expansion stability of the expanded hPDLSCs. After that, growth and OS differentiation of hPDLSCs in Auto- and Allo-HS were investigated. Flow cytometrical analyses, functional differentiations, cell growth kinetic, cytogenetic analysis, alkaline phosphatase and calcium content assays, and oil red O and von Kossa staining were performed. Results showed that at passage 5, HS promoted growth and OS differentiation of hPDLSCs and extensive cell expansion, decreased growth and differentiation potential of the expanded hPDLSCs, particularly in HS. Growth and OS differentiation of hPDLSCs in Auto-HS and Allo-HS were not different. In summary, allogeneic human serum could be a replacement to FBS for hPDLSC expansion. In vitro cell expansion of hPDLSCs should be minimal to ensure optimal cell quality. Copyright © 2016 John Wiley & Sons, Ltd.

Dimensional Change and Microstructure of Intraoral Bone Block Grafts Covered with Platelet-Rich Fibrin and a Barrier Membrane in Ridge Augmentation: A Pilot Investigation.

This study investigated the dimensional change and microstructure of intraoral bone block grafts covered with platelet-rich fibrin (PRF) and a barrier membrane in ridge augmentation. Seven patients were included, with 18 implant sites (10 ramus and 8 symphysis). The average final ridge width gains in the ramus from cast-based measurement (3.86 ± 0.87 mm) and cone beam computed tomography measurements (3.63 ± 1.38 mm) were not different from the symphysis (3.36 ± 2.26 mm and 3.44 ± 1.52 mm, respectively). Ridge width reduction of the ramus (-10.46 ± 10.55%) was higher than the symphysis (-5.04 ± 2.08%). The ramus showed bone volume fractions from the microcomputed tomography (84.66 ± 8.36%) and percentage of bone area from histomorphometry (80.29 ± 12.03%) that were comparable to those for the symphysis (83.13 ± 8.1% and 84.98 ± 14.50%, respectively). The dimensional change of the intraoral block graft covered with PRF and a resorbable membrane was minimal, and the symphysis graft was less resorbed than the ramus graft. Nevertheless, their microstructures were comparable.

Effects of Titanium Surface Microtopography and Simvastatin on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells in Estrogen-Deprived Cell Culture.

PURPOSE: This study aimed to investigate the effects of titanium surface topography and simvastatin on growth and osteogenic differentiation of human bone marrow stromal cells (hBMSCs) in estrogen-deprived (ED) cell culture. MATERIALS AND METHODS: Human BMSCs were seeded on cell culture plates, smooth-surface titanium (Ti) disks, and sandblasted with large grits and acid etched (SLA)-surface Ti disks; and subsequently cultured in regular (fetal bovine serum [FBS]), ED, and ED-with 100 nM simvastatin (ED-SIM) culture media for 14 to 21 days. Live/dead cell staining, scanning electron microscope examination, and cell viability assay were performed to determine cell attachment, morphology, and growth. Expression levels of osteoblast-associated genes, Runx2 and bone sialoprotein and levels of alkaline phosphatase (ALP) activity, calcium content, and osteocalcin in culture media were measured to determine osteoblastic differentiation. Expression levels of bone morphogenetic protein-2 (BMP-2) were investigated to examine stimulating effects of simvastatin (n = 4 to 5, mean ± SD). In vitro mineralization was verified by calcein staining. RESULTS: Human BMSCs exhibited different attachment and shapes on smooth and SLA titanium surfaces. Estrogen-deprived cell culture decreased cell attachment and growth, particularly on the SLA titanium surface, but cells were able to grow to reach confluence on day 21 in the ED-osteogenic (OS) culture medium. Promoting effects of the SLA titanium surface in ED-OS were significantly decreased. Simvastatin significantly increased osteogenic differentiation of human BMSCs on the SLA titanium surface in the ED-OS medium, and the promoting effects of simvastatin corresponded with the increasing of BMP-2 gene expression on the SLA titanium surface in ED-OS-SIM culture medium. CONCLUSION: The ED cell culture model provided a well-defined platform for investigating the effects of hormones and growth factors on cells and titanium surface interaction. Titanium, the SLA surface, and simvastatin synergistically promoted osteoblastic differentiation of hBMSCs in ED condition and might be useful to promote osteointegration in osteoporotic bone.

Bone Regeneration Potential of Biphasic Nanocalcium Phosphate with High Hydroxyapatite/Tricalcium Phosphate Ratios in Rabbit Calvarial Defects.

PURPOSE: This study aimed to evaluate the effect of biphasic calcium phosphate (BCP) with high hydroxyapatite/tricalcium phosphate (HA/TCP) ratios on bone formation in rabbit calvarial defects. MATERIALS AND METHODS: Sixteen New Zealand white rabbits were randomly divided into two groups, a control group and an experimental group. In each animal, bilateral circular defects (10-mm diameter) were created on the calvarium. In the control group (three rabbits per time frame), defects were grafted with autogenous bone chips in one side and left empty in the other side. In the experimental group (five rabbits per time frame), defects were grafted with BCP1 (HA:TCP, 8:2) in one side and BCP2 (HA:TCP, 9:1) in the contralateral side. The animals were sacrificed at 2 and 8 weeks as designated. Bone formation and residual grafting material were assessed by radiographic densitometry, microcomputed tomography (micro-CT), and histomorphometric analysis. RESULTS: Histologic observation revealed that BCP1, BCP2, and the autogenous bone group preserved good contours of the defect, while the unfilled defect group showed connective tissue healing. Micro-CT analysis at 8 weeks showed the comparable percentages of bone volume fraction (% BV/TV) of BCP1 (20.70% ± 2.76%) and BCP2 (20.72% ± 3.97%) and two times higher than that of 2 weeks (9.90% ± 0.75%, 10.57% ± 0.85%). The autogenous group had a significantly (P < .005) greater % BV/TV (34.58% ± 8.85%) than other groups. The percentage of the material volume fraction of BCP1 and BCP2 was not different. The histomorphometry demonstrated a higher increase in newly formed bone from 2 to 8 weeks in all groups, and all were comparable (autogenous: 4.30% ± 0.76%, 12.83% ± 7.74%; unfilled: 2.82% ± 1.19%, 8.14% ± 6.35%; BCP1: 3.01% ± 2.57%, 8.81% ± 3.86%; BCP2: 3.24% ± 1.09%, 10.27% ± 3.98%). CONCLUSION: BCP with a high ratio of HA presented good osteoconductive properties and space-maintaining capacity and would be beneficial for long-term preservation or when stable graft volume is essential.

In vitro biocompatibility analysis of novel nano-biphasic calcium phosphate scaffolds in different composition ratios.

This study aimed to evaluate in vitro biocompatibility of a composite of nanoscale biphasic calcium phosphate (BCP) and collagen (C) compared to pure BCP (P) in different composition ratios of nanohydroxyapatite to nano-ß-tricalcium phosphate (HA/ß-TCP). Each study group comprised of three ratios of BCP (30/70, 40/60, and 50/50). For evaluation of cellular response toward each ratio, mouse osteoblast (MC3T3-E1) cell line was cultivated on the scaffolds for 19 days. Analysis of cell proliferation, cell viability, cell attachment and morphology, alkaline phosphatase (ALP) activity, and osteocalcin synthesis were done on culture days 1, 3, 7, 13, 15, and 19, appropriately. The scanning electron microscopy showed that the osteoblasts attached successfully to scaffolds surfaces in both BCP groups and in all different ratios by spreading their filopodia and expressing similar viability that was confirmed by confocal laser scanning electron microscope. BCP scaffold (P3070) showed remarkable ALP activity, whereas BCP (P5050) showed highest osteocalcin activity. Collagen coating supported high cell proliferation on culture day 1 and possessed limited benefit restricted to early phase of cell differentiation. In conclusion, the fabricated nanoscale BCP scaffolds offered high biocompatibility and supported well the cell proliferation and differentiation regardless the composition ratio. Furthermore, higher ratio of TCP supported the early phase of cell proliferation, whereas higher HA ratio influenced the later phase. Finally, BCP scaffolds P5050 and C4060 were suggested as candidates for clinical applications.

The primacy of platelet-rich fibrin on bone regeneration of various grafts in rabbit's calvarial defects.

AIMS: This study investigated the effect of platelet-rich fibrin (PRF) on bone regeneration of various grafting materials in rabbit calvarial defects. MATERIAL AND METHODS: Two bicortical skull defects were prepared in 20 New Zealand white rabbits; 10 rabbits were treated with PRF and the other 10 were non-PRF. In both groups, autogenous bone was compare to empty defects in 5 rabbits and the composite of autogenous bone and deproteinized bovine bone versus deproteinized bovine bone (DBB) in the other five. The animals were sacrificed at 8 weeks. Bone formation was assessed by radiographic densitometry and histomorphometric analysis. RESULTS: The mean optical density (OD) and histomorphometric analysis (HA) of the percentage of new bone showed that the PRF groups were significantly higher than the non-PRF groups in the autogenous bone graft (OD: 0.60 ± 0.19 vs 0.36 ± 0.03; HA: 38.03 ± 4.23 vs 26.21 ± 10.58) and the empty defect (OD: 0.29 ± 0.06 vs 0.11 ± 0.06; HA: 18.81 ± 9.27 vs 6.24 ± 5.01), but not in the DBB group (OD: 1.18 ± 0.17 vs 1.07 ± 0.05; HA: 13.067 ± 3.64 vs 9.63 ± 5.47) and the composite group (OD: 0.81 ± 0.15 vs 0.91 ± 0.05; HA: 22.63 ± 3.61 vs 21.29 ± 3.52). CONCLUSIONS: PRF had a positive effect on bone formation when used alone or combined with autogenous bone, but not with deproteinized bovine bone.

Fabrication and characterization of novel nano hydroxyapatite/ß-tricalcium phosphate scaffolds in three different composition ratios.

The biphasic calcium phosphate (BCP) concept was introduced to overcome disadvantages of single phase biomaterials. Different composition ratios of BCP bioceramics have been studied, yet controversies regarding the effects of ratio on biomaterial behavior still exist. In this study, BCP scaffolds were prepared from nano hydroxyapatite (HA) and ß-tricalcium phosphate (ß-TCP) that were synthesized via a solid state reaction. Three different composition ratios of pure BCP and collagen-based BCP scaffolds (%HA/%ß-TCP; 30/70, 40/60, and 50/50) were produced using a polymeric sponge method. Physical and mechanical properties of all materials and scaffolds were investigated. SEM showed overall distribution of both macropores (80-200 µm) and micropores (0.5-2 µm) with high interconnected porosities. Total porosity of pure BCP (90% ± 3%) was found to be higher than collagen-based BCP (85% ± 2%). It was observed that following sintering process, dimensional shrinkage of large scaffolds (39% ± 4%) was lower than small ones (42% ± 5%) and scaffolds with high HA ratios (50%) experienced higher dimensional changes than those with higher ß-TCP (70%) ratios (45% ± 3% and 36% ± 1%, respectively). Compressive strength of both groups was less than 0.1 MPa and collagen coating had almost no influence on mechanical behavior. Further studies may improve the physical properties of these scaffolds and investigate their exact biological behaviors.

Effects of autogenous growth factors on heterotopic bone formation of osteogenic cells in small animal model.

AIMS: This study used a new approach to investigate the effective concentrations of growth factors released from platelet concentrate (PC) on the bone formation capacity of osteogenically differentiated rat bone marrow stromal cells (rBMSCs). MATERIALS AND METHODS: Rat BMSCs and whole blood were harvested from 40 adult male Spraque-Dawly rats. Rat BMSCs were expanded in an osteogenic medium and seeded on inert collagenous bovine bone matrix (ICBM). Growth factors released from degranulated PC (GFs) containing TGF-ß1 1 (25ng/ml)-10ng (250ng/ml) and rhBMP-2 400ng (10µg/ml) were suspended in 40µl platelet poor plasma (PPP) and applied on the ICBM-rBMSC constructs or ICBM only, respectively. The constructs were then transplanted in autologous hosts for 4 weeks. Concurrently, osteoblastic differentiation of rBMSCs on ICBM-rBMSC-PPP constructs was characterized in vitro. RESULTS: Rat BMSCs in osteogenic medium exhibited phenotypes of mature osteoblasts. The amount of newly formed bone among groups of ICBM-rBMSC-PPP with and without GFs was not significantly different (p>0.05) and was significantly lower than a group of ICBM-PPP-BMP-2 (p<0.05). CONCLUSIONS: Autogenous GFs had no effect on the capacity of rBMSCs to form new bone. The ability to measure the bone formation capacity of transplanted autologous cells and growth factors in a small animal model was demonstrated.

Factors influencing effects of specific COX-2 inhibitor NSAIDs on growth and differentiation of mouse osteoblasts on titanium surfaces.

PURPOSE: To investigate the influence of exposure time and stages of cell growth on the effects of specific COX-2 inhibitor NSAIDs on growth and differentiation of osteoblasts on smooth titanium surfaces. MATERIALS AND METHODS: The study was categorized into 5 groups: group A, 0.1 microM indomethacin; group B, 1.5 microM celecoxib; group C, 3.0 microM celecoxib; group D, 9.0 microM celecoxib; and group E, serum-free culture medium without drug treatment. A mouse calvarial cell line, MC3T3-E1, was seeded on acid-prickled surface titanium disks. The investigations were performed in 3 experimental phases based on stages of cell growth: static (24 hours after seeding), log (culture day 5), and plateau (culture day 12). In each experimental phase, cells on titanium disks were incubated in a medium treated with drugs according to the groups of study for 1, 3, and 5 days. RESULTS: Indomethacin and celecoxib in groups A to D inhibited growth of cells on treatment days 3 and 5 in static phase and on treatment day 3 in log phase. Additionally, an inhibitory effect of indomethacin was greater than celecoxib. Effects on alkaline phosphatase (ALP) activity and osteocalcin were not clearly demonstrated. A significant decrease of PGE2 production was found in groups A to D in static and plateau but not log phases. CONCLUSION: A specific COX-2 inhibitor NSAID, celecoxib, inhibited growth of osteoblasts on titanium surfaces and the effects were influenced by exposure time and stages of cell growth. Using a specific COX-2 inhibitor might cause deterioration of osteointegration of dental implants by interfering with osteoblastic cell growth in the proliferative stage.