Influence of surface roughness of titanium implant on core binding factor alpha 1 subunit of osteoblasts / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To determine whether the roughness of titanium implant can influence its osseointegration by affecting the growth, alkaline phosphatase (ALP) production and expression of core binding factor alpha 1 subunit (Cbfα1) of osteoblasts.</p><p><b>METHODS</b>Totally 48 titanium disc specimens, 15 mm in diameter and 2 mm in thickness, were included in the study and divided equally into 4 groups with 12 specimens in each group. Specimens were coarsened by sandblasting with carborundum granula and acid etching with mixing liquid of hydrochloric acid and sulphuric acid under diverse conditions. In the four groups, three were treated with different surface roughness: micro-roughness [(1.00 ± 0.20) µm], midrange roughness [(1.67 ± 0.08) µm] and severe roughness [(2.40 ± 0.20) µm], while the group untreated with surface roughness [(0.12 ± 0.03) µm] was set as control. Scanning electron microscope, acridine orange fluorescence staining and coomassie brilliant blue staining were used to observe morphology and growth of osteoblasts incubating on these specimens. Enzyme linked immunosorbent assay (ELISA) and fluorescence quantitative real-time polymerase chain reaction were used to evaluate ALP production and gene expression of Cbfα1 of osteoblasts among different groups.</p><p><b>RESULTS</b>Growth, ALP production and Cbfα1 mRNA expression of osteoblasts in experimental groups were higher than those in control group (P < 0.05). Significant differences of these data were also found among three experimental groups (P < 0.05). Midrange roughness group showed the highest level of gene expression of Cbfα1 mRNA, which was 0.93 ± 0.03. While that in the micro-roughness group (0.50 ± 0.03) came second, and the severe roughness group had the lowest data, which was 0.37 ± 0.07.</p><p><b>CONCLUSIONS</b>Results indicated that rough surface was more suitable for the adherence and propagation of the osteoblasts than smooth one did. Surface with roughness of 1-2 µm may be a better choice for osseointegration between osteoblasts and dental implants than others are.</p>

Expression of Ki67 and P53 proteins in gingival tissue after wearing casting alloy crowns / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The aim of the study was to detect the expression of Ki67 and P53 proteins in the gingival tissue before and after wearing three kinds of dental casting alloy crowns.</p><p><b>METHODS</b>The three kinds of dental casting alloys (58% golden alloy, NiCr alloy, NiCr alloy excluding Be) were used to make full crowns for 3 dogs in each group. Another 3 dogs were taken as control. The immunohistochemistry Envision method was used to measure the expression of Ki67 and P53 proteins in the gingival tissue before wearing the crowns, 2 weeks, 1 month, 2 months, 3 months after wearing the crowns.</p><p><b>RESULTS</b>The expression of Ki67 and P53 proteins in gingival tissue increased 1 month after wearing NiCr alloy and NiCr alloy excluding Be, then decreased gradually. And the expression of Ki67 and P53 proteins in 58% golden alloy group was similar to that in control. No pathological change was observed in all samples.</p><p><b>CONCLUSION</b>Two kinds of NiCr alloy crowns both can increase the expression of Ki67 and P53 proteins in gingival tissue, but 58% golden alloy crowns can not. So compared with NiCr alloy crowns, 58% golden alloy crowns have better biological properties. And none of three kinds of dental alloy crowns may induce long-term abnormal proliferation in gingival tissue.</p>

The influence of thickness ratios on the fatigue behaviors of two kinds of dental ceramic / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the intensity changes of different thickness ratios of Empress II glass ceramic and GI- II glass-infiltrated alumina ceramic before and after Hertzian contact cyclic fatigue.</p><p><b>METHODS</b>Disk-shaped specimens of different thickness ratios of Empress II glass ceramic and GI-II glass-infiltrated alumina ceramic were respectively fabricated. Hertzian contact technique was imposed on the specimens. Critical loads of the specimens before and after 10(5) cycles loading were recorded.</p><p><b>RESULTS</b>The average values of critical loads of all specimens reduced significantly after cycles loading (P < 0.05), and critical loads declined with diminishing thickness of the core ceramic. The critical load of GI-II glass-infiltrated alumina ceramic was significantly higher than Empress II glass ceramic before and after cycle loading(P < 0.05).</p><p><b>CONCLUSION</b>Cycle loading can reduce the strengths of the two kinds of dental ceramic, and the latter is better than the former in the resistance to fracture and cyclic fatigue. Critical loads of the two kinds of dental ceramic are mainly influenced by the core ceramic's strength and thickness.</p>

Compared study of cyclic fatigue behaviors in two kinds of dental ceramic layers structures / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the difference in strength degradation and morphology damage of two dental ceramic materials after Hertzian contact cyclic fatigue.</p><p><b>METHODS</b>Hertzian contact technique was used to investigate the response of Empress II glass ceramic and GI- II glass-infiltrated alumina ceramic to cyclic fatigue. Critical loads of specimens after different fatigue cycles were recorded.</p><p><b>RESULTS</b>For Empress II glass ceramic, critical load had significantly difference between specimens after 10(5) cycles loading. No significant difference of critical load was found in GI- II glass-infiltrated alumina ceramic after cycles loading.</p><p><b>CONCLUSION</b>GI- II glass-infiltrated alumina ceramic has better capability in resistance to cyclic loading. It may attribute to microstructure of material. Empress II glass ceramic shows a brittle damage model.</p>

Study of DNA damage of buccal mucosal cells after wearing casting alloy crowns / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To test the corrosion behavior of three kinds of dental casting alloys and to investigate the effect of the released metal ions on the DNA damage of dog buccal mucosal cells.</p><p><b>METHODS</b>Three kinds of frequently used dental casting alloys were used to make full crowns for dogs. The concentration of the released metal ions was measured after the restoration of 2 weeks, 1 month, 2 months and 3 months. The DNA damage of buccal mucosal cells was studied by the method of SCGE.</p><p><b>RESULTS</b>The metal ions released from NiCr and NiCrBe were detected in buccal mucosal cells while the amount of the ions released from noble alloy (gold 58%) was too small to be detected. The DNA damage of mucosal cells increased after restoration of NiCr and NiCrBe crowns.</p><p><b>CONCLUSION</b>The noble alloy (gold 58%) is most corrosion resistant of the three alloys and has good biocompatibility. The NiCr and NiCrBe are prone to corrode and have cytotoxicity to cells.</p>