Effects Of Different Mechanical Treatments On The Physicochemical Properties Of Tooth Root Surface And The Biological Behavior Of Cells

ObjectiveOral diseases are the most prevalent human diseases mainly caused by its open and complicated microenvironment extremely rich in bacteria.Among them,dental calculus occurs in the majority of adults worldwide,caused by large amounts of oral bacteria,proteins as well as composed primarily of calcium phosphate mineral salts.It can cause gingivitis,periodontitis and even tooth loss.Therefore,removal of dental calculus is of great importance and necessity.So far,chemical and mechanical treatments are commonly used in dental calculus control and the effect of mechanical treatment is more accurate.At present,mechanical treatment is commonly used in clinic,including supragingival scaling,subgingival scaling and root planning.Instruments mainly include ultrasonic scaling,hand scaling and sandblasting.The cleaning and physicochemical properties of the root biointerface play an important role in the healing of periodontal tissues.The purpose of this study was to explore the effects of different mechanical treatments on the physical and chemical properties of tooth root surface and the biological behavior of human gingival fibroblasts(hGFs),provides new insights to efficiently remove the dental calculus and to understand the interaction between the tooth root interface and cell,which could guide the clinical operation.MethodsThe teeth extracted due to severe periodontal disease with calculus on the root surface were randomly divided into four groups: group U(ultrasonic scaling),group U + H(ultrasonic scaling + hand scaling),group U + S(ultrasonic scaling + sandblasting),group U + H + S(ultrasonic scaling + hand scaling + sandblasting),The teeth extracted without calculus were used as group B(blank control).Three-dimensional surface topography instrument was used to measure the surface roughness of root under different treatments,scanning electron microscopy(SEM)was used to observe the microstructure of root surface,and video goniometer was used to measure the saliva contact angle of root surface to reflect the wettability of sample surface.Human gingival fibroblasts were cultured,and the morphology of the cells cultured on the root surface for 1 day was observed by scanning electron microscopy(SEM).The proliferation of the cells on the 1st and 4th day was observed by CCK-8 method,and the cell viability was predicted.ResultThe root surface topography and roughness were characterized by three-dimensional surface optical profilometer,and there was no significant difference in roughness between the groups(p>0.05).SEM images showed that different mechanical treatments significantly changed the root surface morphology.The untreated root surface of control group(group B),the root surface of group U and group U+H+S were irregular and rough.Under the treatment of U,the root surface has many pits and cracks.Under the treatment of U + H,the surface features of rough but neat scratches.After U+S treatment,the root surface is basically smooth.SCA results showed that the wettability of root samples was different with different treatments,but all of them retained hydrophilic characteristics(<90°).Human gingival fibroblasts(hGFs)were cultured and found to adhere to the root surface by SEM,and its morphology was greatly affected by the change of root surface morphology.CCK-8 method was used to measure the cell activity,and it was found that there was no cytotoxicity on the root surface under different treatments.On day 4,the cell survival rate of treated samples was higher than that of group B,and the cell survival rate of samples treated by U and U+H+S was significantly improved compared with other treatments.ConclusionDifferent mechanical treatment methods have great influence on the physical and chemical properties of root surface,including surface morphology,roughness and wettability.In addition,biological results showed that the behavior of hGF(i.e.cell attachment,morphology,arrangement and proliferation)was influenced by root surface roughness,microstructure and wettability.The results showed that ultrasonic scaling,hand scaling and sandblasting combined treatment could effectively remove calculus,regulate cell response and promote periodontal tissue healing.