The aims of this study were to produce rough surfaces on zirconia by laser treatment and to examine how changes in surface topography affect tissues surrounding zirconia implants. Threaded zirconia implants with a diameter of 2 mm and length of 7 mm were used. The experimental implants had surfaces treated with laser (YAG laser) irradiation (R-ZIs). The controls were not treated with laser irradiation (S-ZrIs). Twenty R-ZIs and twenty S-ZrIs were placed in the tibiae of 8-week-old male SD rats. The peri-implant tissues with implant bodies were collected 4 weeks after implant placement. Light microscopic and histomorphological evaluations were performed, and removal torque (RTQ) was measured. The bone-implant contact (BIC) ratio was approximately 1.25 times higher for R-ZrI than for S-ZrI on the side of the cortical bone, indicating a statistically significant difference (p<0.05). There was no statistically significant difference in their BIC ratios on the side of the bone marrow. On the cortical bone side and bone marrow side, there was no statistically significant difference between R-ZrI and S-ZrI in the peri-implant bone area (BA), the area of peri-implant bone within the implant threads. RTQ was approximately 7 times higher for R-ZrIs than for S-ZrIs, indicating a statistically significant difference (p<0.05). In this study, the results of the animal experiment revealed new bone formation in the surroundings of the zirconia implants at 4 weeks after implant placement, indicating achievement of osseointegration. The results suggest that laser-produced rough implant surfaces effectively enhance osseointegration.
Carbon nanotubes act as a photon antenna that serves as an effective “molecular heater” around the near-infrared (NIR) region. This exothermic generation can be used as a possible heating source for hyperthermia therapy. The current study reports the dispersible and exothermic properties with NIR irradiation for single-walled carbon nanotubes (SWNTs) treated with a strong acid (acid-treated SWNTs), and the SWNTs further functionalized with double-stranded DNA (DNA-functionalized SWNTs: DNA-SWNTs). DNA-SWNTs significantly improved the dispersibility of SWNTs when compared with the acid-treated SWNTs. The binding ratio of the acid-treated SWNT and DNA was calculated to be 3.1 (DNA/SWNTs) from the phosphorous content in the DNA-SWNT. This interaction of the SWNTs and DNA would contribute to the stable dispersion of the DNA-SWNTs in a culture medium. With NIR irradiation by a halogen lamp light source, the acid-treated SWNTs and the DNA-SWNTs showed strong heat evolution in vitro (in a culture medium) and in vivo (in the subcutaneous tissue of a mouse) condition without any invasive effect on the non-SWNT area. The results of this study suggested that the functionalization with DNA was an efficient approach to improve the dispersibility of SWNTs in body fluids, and the DNA-SWNT would be a promising source for photo-induced exothermic generation.
Films were prepared from the powders of DNA/poly-L-arginine, DNA/poly-L-lysine, and DNA/ chitosan complexes via hydrothermal hot-pressing in an effort to make more useful dental materials. The contact angles of water were between 37.6° and 49.9°. Zeta potentials at pH 7.4 were between 10.96 mV and 30.44 mV. The DNA/chitosan complex film showed the lowest contact angle and highest zeta potential. All films showed poor attachment of dermal fibroblast cells, with cells forming spheroids on all films. However, the cells survived on the films after a 5-day cultivation period. The DNA/poly-L-arginine and DNA/poly-L-lysine complex films were almost completely biodegraded within 14 days and most of the DNA/chitosan complex films were biodegraded 90 days after implantation in soft tissues of rats. These results suggest that films formed from DNA/polycation complexes will be useful for clinical treatments requiring thin membranes or films, such as protective membranes for stomatitis and incised oral wounds.
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