インプラント治療の成功率は大抵の医療機関において90％を大きく超えており，予知性の高い治療法であることに間違いはない．しかし，インプラントと天然歯は根本的に違う点があり，それを無視することはできない．歯根膜の存在である．歯根膜は鋭敏な感覚受容器であると同時に，咬合力等の負荷を顎骨に伝える際のショックアブソーバーとしての役割も果たしている．インプラントにはそのような構造はなく，咬合力は直接顎骨に伝えられ，骨伝導と咀嚼筋内の感覚受容器が代償的に機能している．しかし，感覚閾値は天然歯より高く，天然歯では10 g 程度の圧力を感知できるのに対し，インプラントでは100 g の圧力にならないと識別できないといわれている．ゆえにインプラントの咬合を付与する際には，負担過重にならないように注意すべきである．
Implants are currently produced using JIS type 2, type 3, type 4, titanium alloy and cold-worked JIS type 2 titanium. The mechanical properties and amount of released titanium of these materials have been reported. However, the amount of released titanium and fatigue fracture of titanium specimens in various cold-worked stages have not been clarified. Therefore, in this study, JIS type 2 titanium was cold-worked at compression ratios of 10, 20, 30, and 35%, and each test specimen's tensile strength, proof stress, elongation, hardness, fatigue fracture, amount of released titanium immersed in 1% lactic acid solution, and influence on titanium structure were evaluated. As a result, the following conclusions were drawn :
1. Mechanical properties other than elongation improved with cold-working of JIS type 2 titanium.
2. There were no significant differences in the amount of released titanium between the test specimens before cold-working of JIS type 2 titanium (AS) and those after. However, among the cold-worked test specimens, the amount of released titanium was highest in the specimen of C20.
3. The number of repeated bendings until fatigue fracture was higher with C30 than with titanium before cold-working of JIS type 2 titanium (AS), C10, and C20.
4. Regarding structural observation, a fibrous structure was more frequently observed as the compression ratio increased. There was a tendency whereby, when this fibrous structure was uniformly distributed, the amount of released titanium decreased, and the mechanical properties improved.
5. It was suggested that implants produced using C30 have stable mechanical properties, and the possibility of allergy to titanium can thus be reduced.
The present study aimed to demonstrate the influence of surface treatment of fibroblast growth factor (FGF)-2-loaded TiO2 film by H2O2 hydrothermal treatment on in vitro bone bioactivity.
The results suggested that H2O2 hydrothermal treatment resulted in TiO2 films with a lower contact angle and higher hydrophilicity. Early cell adhesion assay by a scanning electron microscope (SEM) suggested that the FGF-2-loaded surface had a high cell density and a significantly higher cell average adhesion area, as well as marked cell extension when compared with the non-FGF-2-loaded surface. MC3T3-E1 osteoblast-like cell proliferation tended to increase with time, with particularly high cell proliferation observed on day 7 and day 14. The alkaline phosphatase (ALP) activity was significantly higher in the FGF-2-loaded group when compared with the nonFGF-2-loaded group.
In conclusion, the results of this study showed that H2O2 hydrothermal surface treatment of FGF-2-loaded TiO2 films can increase early cell adhesion, proliferation and bone differentiation, and contribute to functionalization of the titanium surface, early bone-titanium implant integration and long-term stabilization.
Polylactic acid (PLA) and polyglycolic acid (PGA) are widely used as guided tissue regeneration and/or guided bone regeneration membranes in the dental field. However, these membranes do not have any biological function such as acceleration of cell attachment, cell spreading, proliferation and differentiation. In the present study, we aimed to immobilize fibronectin, cell adhesive protein, to polylactide-co-glycolide (PLGA) film. The biological evaluation of fibronectin immobilized PLGA was investigated by human umbilical vein endothelial cell (HUVEC) culture.
Three types of PLGA (PLA : PGA = 90 : 10 (PLGA10), PLA : PGA = 80 : 20 (PLGA20), PLA : PGA = 70 : 30 (PLGA30)) films were used. The PLGA films were immersed in 0.5 M NaOH solution at 37℃ for 3 h for surface hydrolysis. The hydrolyzed PLGA film was immersed in MES buffer containing water-soluble carbodiimide. Afterwards, the film was immersed in 0.05% fibronectin solution in MES buffer solution for 48 h at 4℃. The fibronectin immobilized PLGA films, namely FN-PLGA10, FNPLGA20, and FN-PLGA30, were obtained. The contact angle of the FN-PLGA surface with respect to double distilled water was measured. Cell assay was performed by using human umbilical vein endothelial cells (HUVECs). The seeded HUVECs were allowed to incubate for 90 min, 3 and 7 days under standard culture conditions. The number of attached cells was evaluated and the morphologies of attached sells were observed by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM).
The contact angle of each FN-PLGA surface decreased compared with PLGA (p＜0.05). The presence of fibronectin on each FN-PLGA was confirmed by attenuated total reflection Fourier transform infrared spectroscopy (FTIR-ATR). The number of attached cells on FNPLGA10 was significantly greater than that on PLGA10 after 90 min, 3 and 7 days (p＜0.05). For FN-PLGA20, the number of attached cells was significantly higher than that on PLGA20 after 90 min and 7 days (p＜0.05). FN-PLGA30 showed a significantly greater number of attached cells than FN-PLGA30 after 90 min (p＜0.05). The number of attached cells on FN-PLGA10 was significantly greater than that on FN-PLGA20 and FN-PLGA30 after 3 and 7 days (p＜0.05). HUVECs attached to each FN-PLGA exhibited spread morphologies and the formation of pseudopodia. For each PLGA, rounded morphologies of cells and less formation of pseudopodia were observed. More actin filaments and stress fibers on FNPLGA10 were observed compared with PLGA10 by CLSM observation.
In conclusion, it was revealed that fibronectin immobilization of PLGA film was effective for biological activity. In addition, the ratio of PLA and PGA in PLGA influenced the attachment and proliferation of cells.
The evaluation of specific binding characteristics for bone-associated cytokines, especially chemokines, on titanium (Ti) surfaces may serve to clarify the mechanism of osseointegration during wound healing in the early stage of implant placement. It was recently reported that CXCL12 (SDF-1 : Stromal cell-derived factor 1) - CXCR4 chemokine signaling is expressed during bone healing and osseointegration of implants, and these chemokines play a critical role in homing and migration of mesenchymal stem cells. Accordingly, the analysis of response and application of these chemokines against titanium implants are becoming increasingly important. This study evaluated the binding behavior of chemokine CXCL12 on surface-modified Ti with superhydrophilicity, because superhydrophilic surface modification is expected to enhance the adsorption of proteins to titanium. In addition, the mechanism of enhancing adsorption of CXCL12 is considered by the surface analysis.
Atmospheric-pressure plasma treatment (Ti-Plasma), ultraviolet treatment (Ti-UV) and sodium hydroxide treatment (Ti-NaOH) as a superhydrophilic treatment were performed on a titanium sensor that was designed for quartz crystal microbalance (QCM) apparatus. Untreated gold (Au-Air) and titanium sensor (Ti-Air) were used as controls. Surface topography, wettability and surface characteristics were evaluated. In addition, adsorption properties of CXCL12 were assessed using the QCM method.
Superhydrophilicity was confirmed for all treatment groups including Ti-Plasma, Ti-UV and Ti-NaOH. Surface analyses showed that oxide was hardly found on Au-Air, whereas both oxide and hydroxide were found on Ti-Air. Furthermore, an apparent decrease of carbon content and increase of hydroxide were found on the superhydrophilic treatment groups compared to Ti-Air. The specific binding of CXCL12 adsorption was increased on the superhydrophilic treatment groups compared with Ti-Air. Possible mechanisms of the increase of CXCL12 adsorption on the superhydrophilic surfaces were considered to be due to the increase in surface energy caused by removal of hydrocarbons and increase in hydrogen bonds by relating the hydroxide. These results suggested that the superhydrophilic modifications may enhance the adsorption of CXCL12 as well as the migration of mesenchymal stem cells to titanium implants in the bone marrow.
Objective : The objective of this study was to evaluate the effect of various surface treatments to a zirconia framework material on bond strength of a direct composite material.
Materials and Methods : A direct composite material (Clearfil Majesty) was bonded to the zirconia disks treated with the following primers (n = 11) : Clearfil Ceramic Primer (CCP), Clearfil Photo Bond (CPB), Estenia Opaque Primer (EOP), MR Bond (MRB), Porcelain Liner M (PLM), Porcelain Liner M Liquid B (PLB), Universal Primer (UNP), or no priming (CON). The shear bond strength was tested after 24 hours' water storage. Data were analyzed with the Steel-Dwass U test (p = 0.05).
Results : The CPB group showed the significantly highest bond strengths. The CCP and EOP groups had significantly higher bond strength values than the CON, MRB, PLB, PLM, and UNP groups, whereas the CON group revealed the lowest bond strengths.
Conclusion : Combined application of a hydrophobic phosphate monomer (MDP) and polymerization initiators enhanced the bond strength of a direct composite material to a zirconia framework material.
With the advent of highly biocompatible titanium implants, implant therapy has been considered as a predictable dental treatment in recent years. However, there have been reports on poor prognosis of implant cases. Although most of these reports are related to peri-implantitis or paresthesia, there are some reports on titanium allergy cases. We have experienced one case of metal allergy ; this report presents a patient who developed oral lichen planus after implant placement.
The patient was a 56-year-old female with no significant past medical or dental history. She came to our clinic in January 2012 with a chief complaint of a mobile right mandibular molar. The second molar was extracted due to a root fracture. Her pre-operative blood tests did not show any abnormality other than a slightly elevated cholesterol level. One implant was placed at the site in June. After the surgery, she started to complain of mild spontaneous pain on the bilateral posterior buccal mucosa. We decided to watch the condition and wait. Then we observed lacy white patches on both sides of the posterior buccal mucosa at the time of re-entry in September. In October, a provisional restoration was set in her mouth. Since the symptoms did not improve, a histopathological examination was performed in February 2013 and a definitive diagnosis of oral lichen planus was made.
Even though the metal allergy was suspected as a cause of her oral lichen planus, it had been very difficult to diagnose her metal allergy before the implant surgery as there were already many metal restorations placed in her mouth. Therefore, we believe that it is necessary to consider the possibility of metal allergy before initiating implant therapy and it is advisable to add the metal allergy test to the set of pre-operative examinations such as systemic blood screening tests.
With the aim of ensuring safe administration of intravenous sedation with midazolam (MZ), we established an intravenous sedation management system, integrating related devices by a biomedical engineering approach, and applied the system to clinical use. Regarding the dose/dosage regimen of MZ, an infusion software program was created using trustworthy expertise, relevant guidelines and so forth to calculate the clinical dosage/administration. The software not only helps prevent risk in the amount of MZ administered, but also enables the simulation of various conditions. To the Video Overlay Monitoring System (VOLMS) software, which allows the vital signs and electrocardiograms displayed on the monitor to be superimposed on intraoperative images on the display, we added a software program in intravenous sedation mode. This software program allows the total dose infused from the syringe pump, the elapsed time after the end of MZ administration, and the management time to be displayed on the VOLMS display. The system achieves seamless and unified management of the essential information in intravenous sedation that was previously separated in the syringe pump and the monitor. We used the system in clinical practice for implant placement surgery in a 67-year-old woman weighing 61.6 kg. The results showed a total dose of MZ at 5.45 mg in 73 min through the end of the administration. The range of vital sign fluctuations after induction was narrow, largely staying near the preoperative values. Thus, the system with infusion software installed proactively ensures safety in intravenous sedation. Additionally, the images and numerical data recorded in the system supply extremely detailed information for retrospective research studies.