The Cytotoxicity Of Three Kinds Of Dental Prosthesis Grinding Dust To Mouse Macrophages

Objective:Long-term exposure to dental prosthesis grinding dusts can cause respiratory diseases such as pulmonary fibrosis,silicosis,and others.The toxicities and pathogenicities of PMMA resin dust,Vitallium metal dust,and porcelain dust were determined by applying them to RAW264.7 mouse macrophages,detected indicators related to its toxicity and provided basic data for personal protection of oral workers.Methods:1.Three types of dental prosthesis grinding dust were collected and used in simulated clinical operations.Samples were characterized for dust morphology,particle size,and elemental composition by scanning electron microscope?SEM?,laser particle size analyzer?PSDA?and energy dispersive spectrometer X-ray?EDX?.2.The grinding dusts were applied to RAW264.7 mouse macrophages at the rates of 300?g mL^-l,and the morphological changes of cells were observed by light microscopy and acridine orange?AO?fluorescence staining to investigate the effect of dental prosthetic grinding dust on the morphology of RAW264.7.3.The grinding dusts were applied to RAW264.7mouse macrophages at the rates of 50?g mL^-l,150?g mL^-l,300?g mL^-l,450?g mL^-l,and 600?g mL^-l.In vitro cytotoxicity assays,the content of lactic dehydrogenase?LDH?in the culture supernatant was detected after 24h and 48h,and the levels of reactive oxygen species?ROS?were detected after 6h,12h,24h and 48h.Statistical analysis was performed using factorial design analysis of variance,one-way analysis of variance,and other statistical methods to further investigate the possible mechanism of dust damage to RAW264.7 mouse macrophages.Results:1.The three types of dental prosthesis grinding dust had different morphologies,particle sizes,and elemental compositions.The PMMA group was agglomerate,the edges were blunt and irregular,the Vitallium group was flaky,the edge shape was irregular,and the porcelain group was cubic,and the edges were sharp and irregular.The dust particle size distribution was wide,and the particle size changed significantly small after fine grinding.PMMA dust was mainly composed of C and O,Vitallium dust was mainly composed of Cr,Co and Mo,and porcelain dust was mainly composed of Si,Al and O.2.They also presented with varying degrees of RAW264.7 macrophage cytotoxicity.Light-and fluorescence microscopy revealed that the dusts were adsorbed to the cell surfaces and induced morphological changes such as pseudo-foot elongation,irregular shapes,lysis,and ballooning.Nuclear migration and elongation of the pseudopods of the dust-collecting cells were observed after AO fluorescence staining.3.The grinding dusts were applied to RAW264.7 mouse macrophages at the rates of 50?g mL^-l,150?g mL^-l,300?g mL^-l,450?g mL^-l,and 600?g mL^-l.The results of LDH and the levels of ROS showed that with the prolongation of time and concentration,the release of LDH and ROS increased,the difference was statistically significant?P<0.05?.The LDH and ROS of porcelain dust group were higher than Vitalium group and PMMA group and the difference was statistically significant?P<0.05?.Conclusions:1.All three dental prosthesis grinding dusts were toxic to RAW264.7 cells.With the prolongation of time and the increase of concentration,the LDH and ROS produced by the cells increased,suggesting that the dust toxicity had a certain time and dose dependence and prompting clinicians should minimize dust exposure.2.The cytotoxicity of porcelain dust was greater than that of the Vitallium metal and PMMA resin dusts.3.LDH and ROS changes were consistent of 24h and 48h.A possible cytotoxicity mechanism is the induction of lipid peroxidation and plasma membrane damage after the dusts penetrate the cells.Therefore,clinicians who are regularly working with these materials should wear the appropriate personal protection equipment to minimize exposures and reduce the health risks associated with them.