| Nowadays, metal ceramic restoration is still relatively widely used as dental restoration materials in clinical practice. However, there are also aesthetic, biological and other defects. All-ceramic materials have the trend to displace Alloy PFM, but the common all-ceramic materials are relatively brittle and their mechanical strength is relatively low. So they can easily break and crush, causing the failure of restoration. Zirconia ceramic materials as oxide ceramic materials good at mechanical properties overcome these defects. They are hot in the research of dental restoraion materials in recent years and are the trend for future development, catching the eyeballs of researchers both at home and abroad. However, their production process is relatively complicated and now, there are no domestic artherectomy zirconia materials suitable to dental CAD/CAM system abroad. This research is based on successfully adopting chemical coprecipitation to synthesize powder, advanced molding to process soft blank zirconia ceramic for the use of CAD/CAM and finally sintering RF type zirconia ceramic materials. It evaluates their biological safety and provides the sound proof for their clinical use.ObjectiveTo detect the biological safety of RF all-ceramic materials .To explore the possibility of its clinical application and provide experimental basis for its clinical application in the future.Methods1. According to the standard of national pharmaceutical industry and the international standard, this paper evaluates the biological safety of materials by conducting cytotoxicity test, acute systemic toxicity test, hemolysis test and oral mucosa irritation test on RF type zirconia ceramic materials.2. This paper detects whether RF type zirconia ceramic materials are radioacitive or not by using inductively coupled plasma spectrometer system, laser etching and Thermo Spec/CID analysis system. The above provides sound proof for higher safety in clinical use.Results1. Acute systemic toxicity test shows that experimental mice have all freedom of movement in observation period without any mortality. After injecting extracts of two materials, their weight has no statistic difference (P>0.05) and increases as normal. All the mice can drink and eat as usual with high spirit. They respond rapidly without any toxic reactions. Liver and kidney show no congestive phenomenon and inflammatory cells.2. The cells in extract group of RF and e.max type zirconia ceramic materials grow well with high growth density. These cells are diamond or strip-shaped, similar to negative control group without any abnormality. Also, at every point time(1, 3, 5d), they show obviously higher sign than positive control group and have no obvious differences compared with negative control group, grading 0 in toxicity. 3. The hemolysis rate is 0.5% in the group of RF type zirconia ceramic materials, less than the standard of 5%. Thus, RF type zirconia ceramic materials have no hemolyticity and cannot cause hemolytic reactions.4. In oral mucosa irritation test, naked eyes observe that the contact area of specimen and mucosa is normal with no erythema; under glass, cheek pouch tissue is regularly scored below 4. Combining these two experiments, RF and e.max type zirconia ceramic materials don't irritate oral mucosa.5. After detecting RF type zirconia ceramic materials through LA-ICP-MS, the radioactive elements are much fewer than national standard in RF type zirconia ceramic materials. These materials are not too much different from VITA, Emax imported all-ceramic materials. All in all, RF type zirconia ceramic materials are safely qualified for dental use as all-ceramic materials.ConclusionRF type zirconial ceramic materials have similar biological properties to similar imported materials. The radioactivity of RF type zirconial ceramic materials after detection can satisfy national standard. So, RF type zirconial ceramic materials have great biological safety. |
