[Show abstract][Hide abstract]ABSTRACT: Objectives:
This study investigated the influence of surface reaction-type prereacted glass ionomer (S-PRG) fillers on Candida albicans adhesion on denture base resin.
Discs were prepared by incorporating the S-PRG filler into the polymer powder of a polymethyl methacrylate (PMMA)-based, heat-polymerizing resin at 0 (control), 5%, 10%, and 20% (w/w). The surface roughness of all disc surfaces was measured. Elemental analysis of released Na(+), Sr(2+), SiO3(2-), Al(3-), BO3(3-), and F(-) was performed after water immersion. Each disc was placed in a well with artificial saliva to form acquired pellicle, incubated, washed with phosphate-buffered saline, and immersed in a C. albicans (JCM2085) cell suspension standardized at 10(4) cells/ml. After aerobic incubation at 37°C for 24h, the metabolic mitochondrial activity, total biofilm biomass, and biofilm thickness were evaluated. The morphogenetic transition of C. albicans in the early culture stage (1 and 3h) was observed.
There was a slight but significant increase in the surface roughness with an increase in the filler content. The metabolic activity and total biomass volume were significantly lower in all filler groups than in the control group, although there were no significant differences among the filler groups. Groups with at least 5% filler content exhibited a thinner biofilm compared with the control group. All filler groups showed hyphal forms at 3h, with the length of the hyphae being lesser than those in the control group.
Although the incorporation of S-PRG filler slightly increases the surface roughness of denture base resin, it reduces the adhesion of C. albicans.
The S-PRG filler has the potential to reduce Candida albicans adhesion on denture base resin and may lower the risk of denture stomatitis. However, filler incorporation can increase the surface roughness of heat-polymerizing denture base resin.
Full-text · Article · Dec 2015 · Journal of dentistry
[Show abstract][Hide abstract]ABSTRACT: Ti-based bulk metallic glasses are reported with high strength, low Young modulus and high corrosion resistance, suggesting their potentials in biomedical applications. However a thorough in vivo evaluation of its biocompatibilities has not been conducted yet. In this study, we implanted bars of Ti-based bulk metallic glass in the femoral bone of rats, followed up local tissue reaction as well as its component ions' diffusion in local area and whole body. The Ti-based BMG (Ti40Zr10Cu34Pd14Sn2) alloy exhibited favorable features of both high strength and high elasticity. In vivo implant evaluation showed that it has a good tissue compatibility, equivalent bone integration and bonding ability with Ti sample. No component ion diffusion was detected up to 3 months post implantation. The possibility and efficacy of its use for bone implant is confirmed. Thus further long term implant study is recommended.
No preview · Article · Oct 2015 · Bio-medical materials and engineering
[Show abstract][Hide abstract]ABSTRACT: The objective of this study was to compare the results of allogenic and xenogeneic nerve grafts that were treated using decellularization. The sciatic nerves of Sprague-Dawley rats and the median nerves of Japanese white rabbits were decellularized with sodium dodecyl sulfate and Triton X-100 and examined with a scanning electron microscope and immunofluorescence staining. A bridge-graft into the sciatic nerve in Wistar rats was performed with the decellularized nerves (10 mm in length for short-term evaluation; 15 mm in length for long-term evaluation). As a control, an isograft was performed. The specimens were harvested at 4 weeks postoperatively and prepared for immunohistochemistry. Function, electrophysiological and histomorphological analyses were performed to evaluate nerve recovery at 24 weeks postoperatively. The 3-dimensional structure of the basal lamina column, on which the cell adhesion molecules were integrated, was preserved through the decellularization protocols. Limited ED1-positive macrophage invasion was observed, and abundant NF 160-positive axons, which were accompanied by S-100-positive Schwann cells, penetrated through the implanted nerves. The sciatic nerve function and electrophysiological and histomorphological analyses suggest that the xenogeneic nerve graft was statistically indistinguishable from the allogenic nerve graft but slightly inferior to the isograft in supporting the axonal regeneration and functional recovery. This article is protected by copyright. All rights reserved.
No preview · Article · Oct 2015 · Journal of Biomedical Materials Research Part A
[Show abstract][Hide abstract]ABSTRACT: The authors evaluated the efficacy of decellularized nerve as a scaffold for nerve regeneration.
Sciatic nerves harvested from Sprague-Dawley rats were decellularized in combination with sodium dodecyl sulfate and Triton X-100, and examined with scanning electron microscopy and immunofluorescence staining. A graft into the sciatic nerve in Wistar rats was performed with the decellularized Sprague-Dawley rat sciatic nerves [allograft: 10 mm long (n = 3) for short term and 15 mm long (n = 5) for long term]. As a control, a portion of sciatic nerve of Wistar rats was cut, reversed, and resutured in situ [autograft: 10 mm long (n = 3) and 15 mm long (n = 5) for different terms, respectively]. Samples were harvested 4 weeks postoperatively and prepared for immunohistochemistry. Von Frey hair test, static toe spread factor measurement, and electrophysiologic and histomorphologic analyses were carried out to evaluate nerve recovery 24 weeks postoperatively.
Scanning electron microscopic images revealed the honeycomb structure, and immunohistology showed that the three-dimensional structure of the basal lamina column on which cell adhesion molecules are integrated is preserved through the decellularization protocols. Limited ED1-positive macrophage invasion was found through the decellularized sciatic nerves, suggesting that antigenicity remained more or less after this treatment. Nevertheless, NF160-positive axons accompanied by S100-positive Schwann cells penetrated through the decellularized sciatic nerves. Sciatic nerve function had recovered, and there were no significant differences in the electrophysiologic and histomorphologic recovery in the groups.
These results suggest that the decellularized allogeneic nerve is a suitable scaffold to bridge a nerve gap.
No preview · Article · Sep 2015 · Plastic and Reconstructive Surgery
[Show abstract][Hide abstract]ABSTRACT: This study introduces the application of method for electrically polarizing titanium implants coated with anatase TiO2 using micro-arc oxidation. It also describes the features of the electrically polarized titanium implants, on which surface charges are generated by the dipole moment of the TiO2, and describes how the surface charges affect the implants' in vivo bone-implant integration capability. A comprehensive assessment using biomechanical, histomorphological and radiographic analyses in a rabbit model was performed on polarized and non-polarized implants. The electrically polarized surfaces accelerated the establishment of implant biomechanical fixation, compared with the non-polarized surfaces. The percentage of the bone-implant contact ratio was higher using polarized implants than using non-polarized implants. In contrast, the bone volume around the implants was not affected by polarization. Thus, using the polarized implant, this study identified that controlled surface charges have a significant effect on the properties of titanium implants. The application of the electrical polarization process and the polarization-enhanced osteoinductivity, which resulted in greater bone-implant integration, was clearly demonstrated.
No preview · Article · Sep 2014 · Journal of Biomedical Materials Research Part A
[Show abstract][Hide abstract]ABSTRACT: Connective tissue attachment to a mesh structure incorporated on the surface of oral implants and extra-oral endosseous craniofacial implants (EOECI) was investigated. Two types of implants were prepared: TI and TI-Mesh. TI was composed of an upper and a lower component, both comprised of a titanium cylinder, which could be connected using a titanium screw. The composition of the TIMesh was similar, but the lower cylinder had a lateral groove that was covered with a titanium mesh. In animal experiments performed using rat calvaria, the lower component was first implanted and was left submerged for 3 weeks, then the upper component was mounted percutaneously. After an additional 2 weeks, each implant and the surrounding tissues were harvested and evaluated. Histological observations revealed collagen fibers originating from surrounding hypodermal tissues anchored to the mesh structures of the TI-Mesh whereas no such collagen fibers were observed around TI. Significantly greater values of the attachment strength, the thickness of the dermal tissue, the thickness of hypodermal tissue, and the attachment lengths were observed in TI-Mesh than those of TI. Thus connective tissue attachment with collagen fibers anchored to the mesh was achieved by incorporating mesh structures into the percutaneously placed implants.
[Show abstract][Hide abstract]ABSTRACT: Although artificial vessels are available for large diameter arteries, there are no artificial vessels for small diameter arteries of < 4 mm. We created a decellularized vascular scaffold (length, 10 mm; outer diameter, 1.5 mm; inner diameter, 1.3 mm) from rat abdominal arteries. We measured the biomechanical characteristics of the scaffolds, implanted them to defects made in rat carotid arteries, and evaluated their patency and the endothelial cell linings. Silastic grafts were implanted as controls. The decellularized scaffolds demonstrated similar mechanical characteristics to normal arteries. All of the control grafts were occluded. Fibroblast-like cells were discovered in the thrombus, and fibrous organization was apparent. In contrast, patency of the grafts in 10 of 12 animals was observed 4 weeks after implantation. The internal cavity of the patent scaffold was completely lined by endotheliallike cells. Thus, the possibility of small artery reconstruction using decellularized scaffolds was demonstrated.
[Show abstract][Hide abstract]ABSTRACT: Objective: The objective of this study was to examine subperiosteal bone formation around implanted biomaterials in association with orthodontic anchorage devices.
Methods: Three types of titanium rod specimens with a machined surface (Bare), a hydroxyapatite coating (HAp), and a hydroxyapatite/collagen nanocomposite coating (HAp/Col) were prepared. To verify bone-forming capability around these rods, we carried out animal experiments. Experimental animals were 12-week-old male SD rats. The specimen was implanted into their calvaria. The bone-forming capability of each of the five specimens was evaluated after four weeks implantation via histological observations, bonding strength tests, and CT image analysis. The histometrical and mechanical test data were statistically analyzed using multiple comparisons of Wilcoxon’s rank-sum tests in combination with the Bonferroni-Holm correction.
Results: In the histological observations, all the Bare specimens were completely encapsulated with soft tissue. In the cases of HAp, the specimens were also encapsulated in three of the five specimens, but the other two specimens were not completely encapsulated. In the case of HAp/Col, all of the specimens were almost completely surrounded by new bone tissue. Significant differences were observed in the bone contact ratios between HAp/Col vs. Bare and HAp/Col vs. HAp. Significant differences were also observed in the new bone height between HAp/Col vs. Bare and HAp vs. Bare. From the bonding strength tests, HAp/Col was found to have the greatest mean strength vs. Bare and HAp, and significant differences were observed among them. In the CT image analysis, fractured bone pieces were observed in the cases of HAp and HAp/Col. The size of these fractured pieces was apparently larger in HAp/Col than in HAp.
Conclusion: In an animal experiment utilizing rat calvaria, hydroxyapatite/collagen nanocomposite-coated Ti rods demonstrated new bone formation without fibrous tissue encapsulation as early as within four weeks.
[Show abstract][Hide abstract]ABSTRACT: Chitosan nonwoven mesh conduit was introduced with perforating pores on the wall by laser-drilling process. The pore size was set at 200 μm and the pore interval at 1mm. Twelve mm long grafts of following 4 groups (N=5, respectively) were implanted to rat sciatic nerve defects: non-pore, 2 lines of pores, 4 lines of pores and isograft. After 12 weeks standard nerve function evaluations were performed including functional test, electro conductivity test and histological analysis. It was found that revascularization of the conduit contents was improved with pores drilled, but accompanied nerve regenerative improvements were only shown as maturation of fasciculi, not with the general parameters of axon diameter and density.
No preview · Article · Jan 2013 · Journal of Biomechanical Science and Engineering
[Show abstract][Hide abstract]ABSTRACT: The impact of continuous flow left ventricular assist device (LVAD) pumping on platelet aggregation was investigated in animal experiments utilizing six calves. A single-use MagLev centrifugal blood pump, MedTech MagLev, was used to bypass the calves' hearts from the left atrium to the descending aorta at a flow rate of 50 ml/kg/min. The LVAD's impact on blood coagulation activities was evaluated based on the platelet aggregability, which was measured with a turbidimetric assay method during the preoperative, operative, and postoperative periods. Heparin and warfarin were used for anticoagulation, while aspirin was used for the antiplatelet therapy. A decrease in platelet aggregation immediately after the pump started was observed in the cases of successful long-term pump operation, while the absence of such a decrease might have caused coagulation-related complications to terminate the experiments. Thus, the platelet aggregability was found to be significantly affected by the pump, and its initial trend may be related to the long-term outcome of the mechanical circulatory support.
No preview · Article · Oct 2012 · Journal of Artificial Organs
[Show abstract][Hide abstract]ABSTRACT: The adaptive nature of bone formation under mechanical loading is well known; however, the molecular and cellular mechanisms in vivo of mechanical loading in bone formation are not fully understood. To investigate both mechanisms at the early response against mechanotransduction in vivo, we employed a noninvasive 3-point bone bending method for mouse tibiae. It is important to investigate periosteal woven bone formation to elucidate the adaptive nature against mechanical stress. We hypothesize that cell morphological alteration at the early stage of mechanical loading is essential for bone formation in vivo.
We found the significant bone formation on the bone surface subjected to change of the stress toward compression by this method. The histological analysis revealed the proliferation of periosteal cells, and we successively observed the appearance of ALP-positive osteoblasts and increase of mature BMP-2, resulting in woven bone formation in the hypertrophic area. To investigate the mechanism underlying the response to mechanical loading at the molecular level, we established an in-situ immunofluorescence imaging method to visualize molecules in these periosteal cells, and with it examined their cytoskeletal actin and nuclei and the extracellular matrix proteins produced by them. The results demonstrated that the actin cytoskeleton of the periosteal cells was disorganized, and the shapes of their nuclei were drastically changed, under the mechanical loading. Moreover, the disorganized actin cytoskeleton was reorganized after release from the load. Further, inhibition of onset of the actin remodeling blocked the proliferation of the periosteal cells.
These results suggest that the structural change in cell shape via disorganization and remodeling of the actin cytoskeleton played an important role in the mechanical loading-dependent proliferation of cells in the periosteum during bone formation.
[Show abstract][Hide abstract]ABSTRACT: Mac-3 staining after treatment in mechanical loading. Tibial histological sections were prepared at day 3. These sections were stained with anti-Mac-3 antibodies. (A, C) In the right tibia, used as a control, Mac-3-positive cells were rarely detected in either short-pulse or long-pulse group. (B) In the left tibia in the short-pulse group, Mac-3-positive cells were detected around the loading point (arrow). (D, E) In the left tibia in the long-pulse group, Mac-3-positive cells were also detected around the loading point (E, arrow), but not at the side opposite to the loading point (D). Non-specific signals were detected in osteogenic layer. Scale bar; 50 µm (A–D), 200 µm (E). Red arrowhead indicates loading direction.
[Show abstract][Hide abstract]ABSTRACT: A novel hydroxyapatite (HAp)/poly(L-lactic acid) (PLLA) nanocomposite nonwoven fabric, which was coated and mixed with calcined HAp nanocrystals, and has submicron-sized dimples on its surface, was fabricated. First, HAp-mixed PLLA fabric was prepared by electrospinning a HAp nanocrystal dispersion in dichloromethane (DCM)-dissolved PLLA. It was found that most of the HAp nanocrystals were not exposed on the HAp-mixed PLLA fiber surface but covered with the PLLA matrix. A HAp-nanocrystal coating was applied onto the surface of the HAp-mixed PLLA fabric after corona discharge treatment followed by ethanol washing. The submicron-sized dimples were enlarged after the ethanol washing. After the HAp-nanocrystal coating, the HAp-mixed PLLA fabric surface was uniformly coated with the HAp nanocrystals. In vitro cell spread tests showed that the rat osteoblasts spread more on HAp-nanocrystal-coated fabrics than on non-HAp-coated fabrics. Upon covering calvarial defects, the in vivo hard tissue responses suggested earlier restoration of the defects with HAp-nanocrystal-coated fabrics than those with non-HAp-coated fabrics.
No preview · Article · Jul 2011 · Journal of Artificial Organs
[Show abstract][Hide abstract]ABSTRACT: An experimental periodontal sensor probe (SP) equipped with an optical fiber for recording function was developed. The aim was to test the intraexaminer reproducibility of probing using the SP and to assess the consistency with the manual probe (MP).
The SP was assembled with an external sheath covering the probe tip of an MP. The sheath was slid backward by the free gingival margin while probing and the sliding distance was detected by the sensor. The probing was conducted with the walking stroke at six sites for four first molar teeth in six maintenance patients with the SP and the MP at a 1-hour interval. The deepest reading in the vicinity of each site was recorded. The measurements were rerecorded 1 week later.
The mean depth was 3.03 and 3.08 mm recorded by the MP and SP, respectively. Although no significant difference was found between the probes (P >0.05) in all measurement sites, the mean depth at the lingual site of the upper left first molar was noticeably lower with the SP. For sites ≥7 mm, significantly lower depth was recorded by the SP (P <0.05). Zero discrepancy in duplicate measurements was found in 76% of all sites with MP and 92% with SP.
The reproducibility of the SP was comparable to that of the MP. The results indicate that for sites of maintenance patients with probing depth <7 mm there was excellent agreement obtained by a single examiner using the SP compared to the MP.
Full-text · Article · May 2011 · Journal of Periodontology