Experimental Study About Rhubarb On The Inhibition Of Artificial Root Caries

Aim: Root caries, as the reaction of dental plaque and metabolic producton tooth, is a chronic disease accompany with destruction of the hard tissue,and the bacteria is accounted the most important reason. It is a commondisease among the elderly, which often occurs on the specific location anddevelop along the stratiform structure of cementum. Its dishing carious cavityleads to the difficulties of good retention form; besides, the poor healthy andcooperation of the elderly increase the treatment difficulty. Following theaging of population, how to prevent the elderly from having the root surfacecaries is becoming a social problem. In recent years, the scholars in the seasand abroad have made a lot of researches in this filed and found that manytraditional Chinese medicine have good prevention and control functions onoral infectious disease, with smaller side effects. Because of the restraint ofsugar metabolism, protein and nucleic acid is synthesized, Chinese rhubarbcan restrain bacterial and has antibacterial function, used in the treatment oforal diseases, has anticarious, beneficial periodontal tissue, promote oralmucosa ulcer healing functions. But there are few reports about the inhibitionof Chinese medicine rhubarb on early root caries. In this experiment, we usedifferent concentrations of rhubarb solution to deal with early root caries,discuss the inhibition of artificial root caries by calcium dissolution test andscanning electron microscopy, then provide experimental basis for naturalmedicine in clinical for prevention and control of root caries.Method:1Preparation of extracted teeth: collect extracted molars40from the oldpeople of60years old or above, which are looseⅢ°due to periodontal disease(10times magnification under the stereo microscope and non-carious root surfaces and no cracks),and curettage periodontal ligament and calculus, thenremove the crown cementum and pulp sector organization in the junction ofCEJ after5min ultrasonic cleaning, formed cementum block about4×4×2mm3in the palatal lateral surface. Then coat acid-resistant layer nailpolish double-deck except the roots surface (experimental area), immerse the cementum bloc--ks in the10％formaldehyde solution and sterilized to prepared.2Preparation of bacterium suspension: Recover the Streptococcus muta--ns (the international standard strain) for48h, then culture the Streptococcusmutans in brain heart infusion medium (BHI) under anaerobic conditions【f(N2)=85％, φ (CO2)=10％, φ (H2)=5％】, and smear after passage threetimes, made the biochemical identification. After identified as Streptococcusmutans using of UV spectrophotometer, adjust the bacterial suspension to OD=1.0with sterile saline.3The establishment of model of artificial root caries: Place the toothtissue in artificial saliva of37℃for24h, then put them into the prepared freshbacterium suspension after the formation of acquired pellicle, each bacteriumwill be replaced every48h for20days. Then we will take out the sample todetermine whether the early caries are formed.4Preparation of rhubarb solution：dissolve the Avoid Decocted Granulein Sterilized distilled water, duplicate according to1:2gradient.16g/L,8g/L,4g/L,2g/L,1g/L are prepared.5Measurement of The minimum inhibitory concentration (MIC): UsingAGAR dilution mothed to determine the minimum antibacterial concentrationof rhubarb against Streptococcus mutans.6Drug treatment for early root caries: Put the early root caries tooth bonesample into fresh bacteria in liquid, and every48hours replace bacterium fluid,respectively with three concentration (MIC and two under minimum antiba-cterial concentrations) solution of rhubarb,20g/L sodium fluoride solution, de-ionized water soak5minutes then in natural air30minutes and last put them back into artificial saliva in the constant temperature box water bath, threetimes a day, so circulate7days.7Observation by scanning electron microscope (SEM): After the dippingin the bacterium suspension, the blocks were rinsed by0.1%PBS buffer forthree times, then put the blocks into2.5％glutaraldehyde immediately to fixfor24h and1％Osmic Acid to fix for2h, then put these blocks into the0.1％buffer again to rinse for three times, after that, put the blocks into50%ethanolfor dehydration step by step, then plate with gold. Observe the experimentalarea structure of tooth using scanning electron microscopy and takephotographs.8Statistical processing: Different leaching of calcium ions in differentbacterium suspension were be analysis by SPSS13.0software, snk-q and thestandard of significance was a=0.05.Results:1The MIC of Chinese rhubarb against S.mutans is8g/L.2Results of quantity of calcium ion release:Choose the rhubarb solution of different concentrations to deal with tooth bo-ne pieces7days, then measure Ca2+dissolution quantity by atomic absorptionspectrophotometer, the results are shown as follows:2.1In the0-48hours, each group Ca2+dissolution quantity increased with theextension of time.2.2At1h,6h,24h,48h four time points, the Ca2+dissolution of8g/L ofrhubarb solution and the NaF group are lower than the blank control group (p<0.05). The Ca2+dissolution of NaF group or8g/L of rhubarb solution is lessthan2g/L of rhubarb solution group and4g/L group (p <0.05), the differencebetween2g/L of the rhubarb solutions and4g/L or the blank control group hasno significant difference (p>0.05), the difference between NaF group and8g/L of rhubarb solution has no significance neither (p>0.05).3Observe by scanning electron microscope (SEM):Blank control group: a great quantity of bacteria adhere to the root surface, the structure of body disappear, hard organization demineralizingformation gaps vary in size and lacuna, is typical of the cellular structure; Athigher magnification, the collagen fiber fracture and digested.20g/L of NaF groups: the bacteria of body surface is obviously less thanthe blank control group, a few of lacuna are formed; lots of globular mineraldeposits arise on the surface.8g/L of rhubarb group: the body surface adhesion a small number ofbacteria, the damage of the surface structure is lighter, still visible the layerstructure of cementum and a small amount of lacuna.2g/L of rhubarb and the4g/L of rhubarb group: the body surface adheremore bacteria, structural is damaged obviously into a honeycomb, but theextent of damage is lighter than the black control group.Conclusion:1Rhubarb from decoction in concentration for8g/L can inhibit the growth ofStreptococcus mutans.2Rhubarb from decoction have certain inhibition on early root caries...