Objectives
This study aimed to investigate the effects of early loads on bone quality and quantity around implants and to compare the effects of early loads on bone quality and quantity with the ...effects of conventional loads.
Materials and Methods
Grade IV‐titanium implants with buttress threads were placed in rat maxillary bone 4 weeks after extraction of first molars. A controlled mechanical load (10 N, 3 Hz, 1800 cycles, 2 days/week) was started via the implants 1 and 3 weeks after implant placement for 2 weeks (early and conventional loads, respectively). Bone quality, defined as distribution of bone cells, types and orientation of collagen fibers, and production of semaphorin3A, its receptor neuropilin‐1, and sclerostin, were quantitatively evaluated.
Results
Early loads substantially and positively affected bone quality by changing the preferential alignment of collagen fibers with increased production of type I and III collagens, semaphorin3A, and neuropilin‐1, increased osteoblast numbers, decreased production of sclerostin, and decreased osteoclast numbers both inside and outside the implant threads, when compared with non‐loaded conditions. Conventional loads changed bone quality around implants slightly. Interestingly, early loads had significantly stronger effects on bone quality and quantity based on the evaluation parameters than conventional loads.
Conclusions
This is the first report to provide scientific evidence for load initiation time based on both bone quality and quantity around implants. These new findings show that implants with buttress threads transmitted early loads optimally to bone tissue by improving bone quality and quantity inside and outside the implant threads.
The aim of the study was to investigate the effect of different surface treatment of titanium (Ti) on the adhesion test results for dental application. Ti substrates roughened by 400 to 1 500-grit ...SiC polish papers and alumina blasting, alkali treated by 5 molar (M) NaOH and KOH solutions and heat treated at the temperature range of 400–800 °C were used in this study. The treated samples were subjected to the adhesion test. According to the results of the adhesion test, the adhesive strength showed the highest value for the blasted titanium among all polished and blasted samples. The Ti samples heated at 650 °C showed the highest adhesive strength among all heat-treated samples. Further, the adhesion test results indicated the higher adhesive strength of chemically treated samples treated by NaOH rather than that by KOH. The polished and heated Ti samples showed the highest adhesive strength among all samples.
Intermittent injection of parathyroid hormone (PTH) is used to treat osteoporosis. The concept of bone quality was updated 20 years ago; however, these updates have not been adopted in implant ...dentistry. This study aimed to investigate the effects of intermittent administration of PTH on bone quality around implants in rat tibiae.
Grade IV-titanium-threaded implants that were 3.5 mm long and 2.0 mm wide were placed in a randomly selected side of the proximal tibiae of 12-week-old female Wistar rats. Three weeks after implant placement, the rats were randomly divided into PTH-administration and saline-injection groups (PTH and VC, respectively; n = 7 per group). Micro-computed tomographical, histomorphometric, and immunohistochemical analyses were performed to evaluate bone quality and quantity surrounding the implants.
PTH significantly increased bone volume and bone mineral density in bones not associated with the implants as compared to these values in the VC group. PTH significantly increased bone area and the amount of collagen within the total inside areas of all implant threads compared to that observed in VC. Moreover, PTH significantly increased the number of osteoblasts, osteocytes, and osteoclasts in the total inside and/or outside areas of all implant threads and altered the ratio of type I and III collagen to total collagen fibers.
Within the limitations of this study, intermittent administration of PTH improved both bone quantity and bone quality based on the types and numbers of bone cells and the types of collagen fibers surrounding implants placed into rat tibiae.
Lubricities of SiO2 Particles Coated with Carbon KOBAYASHI, Katsunori; HIRONAKA, Seiichiro; SUZUE, Masayoshi ...
Journal of the Ceramic Society of Japan,
04/2004, Letnik:
112, Številka:
1304
Journal Article
Recenzirano
Odprti dostop
The anti-gallings and wear resistances of SiO2 particles coated with carbon were investigated by using a Falex (pin/vee block) friction machine, when they were added into lithium soap-lubricating ...grease as solid lubricants. The SiO2 coated with carbon showed higher seizure loads and better wear resistances than graphite. The lubricating actions of these carbon-coated SiO2 particles are due to their presences at the friction interface which decrease the direct contact between the friction surfaces,thus resulting in high seizure loads and wear resistances.
We studied the preparation method of acicular magnesium pyroborate (Mg2B2O5), especially in relation to the prevention of formation of agglomerates, which generally form by heating mortar-ground ...mixture of MgO-H3BO3-KCl. Spray-drying of slurry, which contained reaction components and flux, gave a starting material with Mg and B in amorphous state and Mg and K almost uniformly distributed. The slurry was made by adding hot solution of H3BO3 and KCl to suspended solution of Mg (OH) 2 with 2 : 3 : 7 mole ratio of Mg : B : KCl. Heat treatment of the spray-dried mixture at 750°C gave small acicular crystals of Mg2B2O5 less than ca. 1μm in length without by-product such as MgO and MgB4O7. The product obtained by heating the mixture at 850°C for 3hrs contained only acicular Mg2B2O5 crystals ca. 5-15μm long and ca. 0.5μm thick, and did not contain agglomerates.
カーボン被覆シリカ粒子の潤滑特性 小林, 克則; 広中, 清一郎; 鈴江, 正義 ...
Journal of the Ceramic Society of Japan (日本セラミックス協会学術論文誌),
2004, Letnik:
112, Številka:
1304
Journal Article
To investigate the cause of the adult-onset primary noncommunicating hydrocele testis, protein expressions of water channel aquaporins (AQPs) 1 and 3 in the tunica vaginalis were assessed. Frozen ...tunica vaginalis specimens from patients with adult-onset primary hydrocele testis and control male nonhydrocele patients were subjected to Western blot analysis for the detection of AQP1 and AQP3 proteins. Paraffin-embedded sections of tunica vaginalis specimens were histochemically stained with anti-AQP1 and anti-AQP3 antibodies as well as an anti-podoplanin antibody to stain lymphatic endothelia. Hydrocele fluid was subjected to biochemical analysis. AQP1 protein expression in the tunica vaginalis was significantly higher in patients with adult-onset hydrocele testis than in the controls. The AQP3 protein was not detected in the tunica vaginalis. Histochemically, AQP1 expression in the tunica vaginalis was localized in vascular endothelial and smooth muscle cells. The densities of AQP1-expressing capillaries and lymphatic vessels were similar between the tunica vaginalis of the controls and those of hydrocele patients. Sodium levels were higher in the hydrocele fluid than in the serum. In conclusion, overexpression of the AQP1 protein in individual capillary endothelial cells of the tunica vaginalis may contribute to the development of adult-onset primary noncommunicating hydrocele testis as another aquaporin-related disease.
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