ABSTRACT
Objective: To study the effects of room curing polymethyl methacrylate (PMMA) with nano-silver on the liver tissue and DNA damage of hepatic cells in the mice, and to evaluate the hepatotoxicity of the nanocomposites. Methods: A total of 40 male Kunming mice aged 6-8 weeks were divided into room curing PMMA with nano-silver groups (PMMA-NM groups, 72 h extract liquid, 1/2 72 h extract liquid, 1/4 72 h extract liquid), room curing PMMA groups (PMMA groups, 72 h extract liquid, 1/2 72 h extract liquid, 1/4 72 h extract liquid), negative control group, and positive control group (n=5). All mice were treated by gavage with test compounds at the beginning of experiment and 24 h and 45 h after experiment except the positive control agent, the mice in positive control group were treated with ethylmethylsulfone at 24 and 45 h after experiment, and the mice in negative control group were administrated with the same volume of normal saline by gavage. The eyeball blood of mice was collected for biochemistry analysis of liver 3 h after the final administration. The liver tissue was completely removed immediately after the mice were sacrificed and the organ coefficient was calculated. The percentage of tail DNA (%tail DNA), tail length (TL) and Olive tail moment (OTM) were detected by the in vivo comet assay, and the images were analyzed with analysis software of comet assay. Results: Compared with negative control group, the liver coefficient, the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in liver tissue of the mice in various experimental groups had no significant differences (P>0. 05); the % tail DNA, TL and OTM in PMMA-NM groups and PMMA groups had no significant differeces (P>0. 05). The % tail DNA, TL and OTM of the mice in positive control group were higher than those in negative control group (t= -40. 911, P0. 05). There were no significant differences of the % tail DNA, TL and OTM between PMMA-NM groups at different concentrations of extrat liquid (P>0. 05). Conclusion: Room curing PMMA with nano-silver doesn't have adverse effects on the liver and its function in the mice, and the results of comet assay indicates that the material has no genotoxicity, showing that the composite has good biocompatibility.
ABSTRACT
Objective:To discuss the therapeutic effect of related periodontal surgical treatment and aesthetic rerepair in the patient with residual root and crown of anterior teeth induced by unfitting prosthesis and to clarify the curative effect of periodontal surgical treatment and aesthetic re-repair in the anterior teeth area,and to provide guidance for making the program of clinical treatment.Methods:Two years after repair of the anterior teeth of a patient,the restorations loosed;on the one hand the patient had a toothache of chewing food accompanying gingival bleeding,on the other hand the upper labial frenum was too high,furthermore the upper left incisor apical area showed low density images.After the consultation of periodontics,endodontics,prosthodontics and other disciplines doctors,anterior teeth root canal re-treatment and periodontal basic treatment were adopt as well ascrown lengthening combined with labial freneetomy to restore the normal biological width,additionally apply not only guided bone regeneration (GBR) but also platelet rich fibrin (PRF) to repair the defects of apical bone.One month later,provisional restorations were put into use and then three months later permanent repairs were conducted.Results:The corresponding gingival and gingival papilla shape recoverd perfectly and the height of gingiva coordinated with that of adjacent teeth,in the meantime the upper labial frenum attached normally and there was not obvious space between upper incisors;the morphology and function examination of restoration in maxillary anterior region were both well.The follow-up X-ray showed that the bone density of the defect area was the same as that of the peripheral bone without obvious boundaries.Conclusion:The aesthetic repair of thin biotype referring to anterior area,especially in the complicated re-treatment cases,the intervention of the appropriate periodontal surgical treatment is not only beneficial to obtain the obvious short-term effect,but also positive to stabilize longterm effects.