Effect Of Nano-magnesium Hydroxide Modified AH Plus On The Biological Properties Of MC3T3-E1 In Vitro

Objective: Chronic periapical inflammation is usually accompanied by alveolar bone loss.The damaged periapical tissue can be repaired gradually only by removing the disease source in the root canal and promoting the activity of osteoblasts.AH Plus(AH)has been widely used in the field of dental pulp due to its excellent physical and chemical properties such as good tightness,dimensional stability,self-adhesive property and X-ray resistivity.However,some scholars found that the biological activity of AH was weak.In this study,we putted nano-magnesium hydroxide(nano-magnesium hydroxide,NMH)into AH in the preparation of a modified AH,in order to enhance biological activity of the AH.Due to the low cost of NMH,it can neutralize the acidic products produced by inflammation and promote the formation of new bone.If popularized,it can greatly improve the success rate of root canal treatment,reduce the treatment cost and shorten the healing time of chronic periapical inflammation.The purpose of this study was to study the characterization of nanometer magnesium hydroxide and modified AH and their effects on the proliferation,adhesion and differentiation of mouse pre-osteoblasts(MC3T3-E1).Materials and Methods: The micromorphology and phase composition of NMH were determined by scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD).AH and AH materials containing 3%,5%,and 7% NMH(w/w)were prepared into "disks" with a diameter of 10 mm and a height of 5mm.The micromorphology,pH,and magnesium ion release of AH and modified AH were determined by scanning electron microscope(SEM),pH meter and inductively coupled plasma emission spectrometer(ICP-AES),separately.We prepared NMH and modified AH cell conditioned medium,measured the pH of these samples,and then cultured MC3T3-E1,separately.The CCK-8 assay was used to detect the cell proliferation ability for 1,2,and 3 days.The alkaline phosphatase activity and the expression levels of Runx2,ALP,OCN were used to evaluate the effect of NMH and modified AH on the osteogenic differentiation ability of MC3T3-E1 cells,as assessed by alkaline phosphatase(ALP)staining and real-time PCR,respectively.The scanning electron microscope(SEM)was used to detect the adhesion and spread of MC3T3-E1 cells on the surface of the material.The fluidity of the modified AH was also studied.One-way analysis of variance and LSD-t test were used for statistical analysis.P <0.05 was considered statistically significant.Results: With the increase of the concentration of NMH conditioned medium,the pH value increased,and the difference was significant.Low concentration of NMH promoted MC3T3-E1 proliferation(P <0.05),and high concentration of NMH inhibited cell proliferation(P <0.05).Low concentration of NMH promoted the expression of Runx2,ALP,and OCN in MC3T3-E1(P <0.05).The distribution and release of pH and magnesium in the modified AH group gradually increased with the increase of the NMH addition ratio,and the differences were significant.Among them,AH + 3% NMH had significant effects on MC3T3-E1 proliferation,adhesion and osteogenic differentiation,and the differences were significant.The flowability of AH+3% NMH(17.89 ± 0.09 mm)is lower than AH(21.60 ± 0.11 mm)(P <0.05),but in conformity with ISO standards(17 mm).Conclusions: Modified AH can promote MC3T3-E1 proliferation,adhesion and osteogenic differentiation,especially AH+3% NMH has excellent biocompatibility and biological activity,and it may have great potential in the dental pulp field.