Effects Of Metal Ions On Urease Enzymes Activity Of Actinomyces Naeslundii

BackgroundDental alloys are widly used in clinic prosthodontic treatment. Because of the complex environment in oral cavity. Dental alloys in the patients mouth will release some metal ions which may be result in caries and periodontal diseases. Though a variety of indicated that dental alloys have causticity and release metal ions which can cause toxicity effect such as depressing metabolism of the cell, restraining cell proliferation et al. Comparatively little is known about the role of these metal ions in oral ecological balance.Generally ,the stability of oral ecological environment represents a highly balance achieved by a range of synergistic and antagonistic interactions among the diverse microorganisms ,the stable climax communities that establish on different surfaces in the mouth are associated with oral health and provide benefit by preventing colonization by pathogenic microorganisms. Occasion, this natural balance can break down, usually as result of sustained and severe environmental stresses, leading to overgrowth by previously minor components of the microflora. A consequence of this ecological upset can be the development of caries or periodontal disease.Whether the metal ions released from dental alloys can influence oral ecological balance which correlated with oral health.Ammomia production from urea by ureolytic oral bacteria is believed to have a significant impact oral health and the ecological balance of oral microbial populations. Plaque acidification can lead to the establishment of a cariogenic microflora and demineralization of the tooth, urease enzymes of oral bacteria hydrolyze urea to ammonia which can nutralize plaque acids. The high level of ammonia also can exacerbate periodontal diseases. Moreover the urea metabolism can promote the formation of calculus.Actinomyces naeslundii is a gram-positive,facultative anaerobe that is one of the primary colonizers of superagingival and subgingival plaque. Actinomyces naeslundii may be involved in the pathogenesis of root caries and periodontal disease. Actinomyces naeslundii can produce urease enzymes,hydrolyzingurea to ammonia.How about the affects of metal ions released from dental alloys on urease activity of Actinomyces naesludii?ObjectiveTo investigate the effects of metal ions released from dental alloys on urease activity of Actinomyces naesludii.MethodsActinomyces naesludii WVU45 was grown in brain heart infusion broth (BHI) with different concentration levels of Nickel ions, copper ions,zinc ions.The urease activity was mensurated.ResultsCopper ions and zinc ions inhibited the urease activitye of Actinomycesnaesludii(p<0.05);nickel ions increased the urease activitye of Actinomyces naesludii(p<0.05).Conclusion1. Copper ions(12.5umol/L) could inhibited the urease activity of Actinomyces naesludii in a dose-dependent manner;zinc ions significantly inhibited the activity of Actinomyces naesludii urease at high concentration(100umol/L);However Nickle ions(12.5~100umol/L) could enhance the urease activity of Actinomyces naesludii in a dose-dependent manner.2. Compared with copper and zinc ions, Nickle ions could enhance the urease activity of Actinomyces naesludii more effectively.