Study On A New Root Canal Disinfection Paste

Background:Root canal therapy（RCT）is the main treatment for Pulpitis and periapical periodontitis,which are common and frequent diseases in stomatology.It is significant to reduce the number of microorganisms in the infected root canal system as much as possible,especially to control the reproduction of some specific microorganisms,for improving the success rate of root canal therapy.Intracanal medication（ICM）is an important way to reduce the number of microorganisms in the infected root canal system after mechanical-chemical preparation.Calcium hydroxide（CH）is the most common ICM in clinic.However,existing data show that there are some shortcomings in the clinical application of CH,such as the insignificant effect of CH in the treatment of persistent infection or reinfection of root canal,the long-term use of CH in root canal will reduce the mechanical strength of dentin,and it is difficult to completely remove CH from root canal,etc.According to reports,the failure rate of RCT fails is 19.1%-25.3%.Therefore,it is necessary to develop a new root canal disinfection drug with better effect.With the progress of medicine and the development of science and technology,Chinese traditional medicine is also constantly developing and innovating.With the in-depth study of Chinese medicine,we find that the pharmacological effects of Chinese medicine can also be applied to the treatment of pulp diseases and periapical diseases.Berberine hydrochloride（BBH）has good effects of anti-microbial,anti-inflammatory,regulating bone metabolism,and whether BBH can be used for intracanal antisepsis is concerned by oral doctors.Objective:To develop a new ICM with BBH as the main effective ingredient,detect its physical and chemical properties and evaluate its antibacterial effect and cytotoxicity in vitro,so as to explore the clinical application and research value of BBH in the treatment of infected root canals.Methods:Using polyethylene glycol（PEG）as solvent,BBH solution with concentrations of 1,2,4,8,16,32,64,128,256 g/L was prepared,and disk diffusion method was used to detect the antibacterial effect of each concentration of BBH solution on enterococcus faecalis（E.faecalis）.The effective inhibitory concentration of BBH was obtained.Based on this concentration,a new root canal disinfection paste was prepared,which was mainly composed of BBH,chitosan（CS）,PEG,barium sulfate（Ba SO4）and other auxiliary components,and named as berberine hydrochloride root canal disinfection paste or BBH paste.Then CH paste was used as control to detect the X-ray resistance,p H value and fluidity of BBH paste.Disk diffusion method was used to analyze the antibacterial effect of BBH paste on E.faecalis and the BBH paste with the best antibacterial effect was selected.The cytotoxicity of BBH paste to human periodontal ligament stem cells（h PDLSCs）and human dental pulp stem cells（h DPSCs）was detected by CCK8method.Results:1、The inhibition zone diameters of BBH solutions with concentrations of 32,64,128 and 256 g/L were significantly larger than those of BBH solutions with lower concentrations,and the difference between groups was significant（P<0.05）,and the bacteriostatic effect is better with the increase of concentration.2、BBH paste was prepared in concentrations of 100g/L（BBH₁）and 200g/L（BBH₂）.The BBH paste is yellow and creamy,with a p H value between 7 and 8,neutral or slightly alkaline,similar to CH paste in fluidity and X-ray resistance.3、The inhibition zone diameter of BBH₁,BBH₂and CH paste groups respectively were 11.34±0.28mm,14.65±0.14mm and 6.54±0.22mm,while there was no inhibition zone in the sterile water group.Statistical analysis showed that compared with sterile water group,BBH₁,BBH₂and CH paste groups had certain antibacterial activity（P<0.05）,the antibacterial activity of BBH₁and BBH₂groups was significantly better than CH paste group（P<0.05）,and the antibacterial activity of BBH₂group was stronger than that of BBH₁group（P<0.05）.Therefore,0.2g/m L was selected as the final concentration of BBH paste and cytotoxicity test was conducted.4、The cytotoxicity test in vitro showed that the relative growth rate（RGR）of h DPSCs and h PDLSCs of each group was more than 75%after 24h and 48h,and the toxicity grade was GRADE I,qualified.However,compared with other groups,21 days of leaching solution of CH paste significantly reduced RGR of h DPSCs and h PDLSCs after 48h（P<0.05）,and 14 days of leaching solution of CH paste significantly reduced RGR of h PDLSCs after 48h（P<0.05）,which indicate that BBH paste had lower cytotoxicity than CH paste.Conclusion:BBH paste developed by us has X-ray resistance and fluidity similar to CH paste,has neutral or slightly alkaline p H,has a good inhibitory effect on E.faecalis and has no obvious cytotoxicity to h DPSCs and h PDLSCs in vitro.Therefore,we believe that BBH has the potential and value to be applied in RCT.However,more experimental data,especially clinical research data,are still needed to support the application of BBH paste we developed in clinical treatment.