Experimental And Clinical Study Of Propolis To Treat Infectious Root Canal

Background:Periapical periodontitis is caused by the microorganism infection in the root canal. The microorganism play a role in the occurrence and development of periapical periodontitis. The anaerobic bacterium is well known as the preponderant bacterium causing pulposis and disease of periapical, which account for above two third of oral bacterial amount. At present, infectious root canal is often disinfected by medicine, such as formcresol(FC), camphorated phenol(CP) and calcium hydroxide. But now, studies have confirmed that FC and CP have evident cytotoxicity, which can do harm to body immunization and have cancerogenic possibility, and calcium hydroxide can not eliminate all microorganism of infective root canal, especially pathogenic bacteria of refractory periapical periodontitis or of failure cases of root canal therapy. So study about root canal disinfection medicine which has ideal sterile effect and low cytotoxicity has been paied close attention.Propolis has been reported to treat oral disease in recent years. It has been reported to be atoxinogenic, safe and without drug resistance. There are a lot of studies about propolis, while less studies about sterilization of infectious root canal of propolis.Objective:The objections of this study are to evaluate bacteriostasis effect of domestic-made water-soluble propolis on prevotella intermedia(Pi) , fusobacterium nucleatum(Fn) and mixture of Pi and Fn, and cytotoxicity of propolis to Human periodontal ligament fibroblast. The study investigate efficacy and safety of propolis to treat infectious root canal. Meanwhile, we choose propolis with appropriate concentration to carry out clinical test to obtain information for clinic application of propolis. Materials and Methods:1.Experiment of propolis to inhibit growth of Pi, Fn and mixture of Pi and Fn in vitro. With brain-heart infusion (BHI) medium added by hemin, propolis was diluted to 5 concentrations by fluid dilution method, then they were respectively added into BHI medium to make agar plates containing medicine. Pi, Fn or mixture bacteria was respectively incubated in anaerobic condition into agar plates. After 48 hours, the growth of bacterium in agar plates was investigated. The lowest concentration without growth of bacterium was MBC of propolis for Pi, Fn or mixture bacteria.2.Cytotoxicity of propolis to Human periodontal ligament fibroblast (HPLF). By MTT colorimetric method, we evaluated effect of water-soluble propolis at concentration of 0.6%, 0.4%, 0.2% and 0.1% on relative growth rate (RGR) of HPLF ,which was graded by 5-class toxicity classification method. Calcium hydroxide was used as control group in experiment.3.With completely randomized experiment,72 outpatients diagnosed as chronic apical parodontitis were chosed and randomly grouped to 3 groups(two test groups and one control group).Anterior teeth and bicuspid with simple root were treated and the root canals were prepared by routine methods,then the root canals in two test groups were respectively disinfected by 0.1% propolis or 0.4% propolis, the root canals in control group were disinfected by calcium hydroxide paste. One week later, all subjects were rechecked. The clinical symptom and visit frequency were recorded. Microorganism samples in root canals were obtained with paper points respectively pre-preparation , post-preparation and after sterilization. Samples were cultured in BHI blood agar culture-medium, after 48 hours anaerobic culture, the morphous of bacterial colony was observed and predominant bacteria were chosed and categorized by gram staining. The bacteria colony number was recorded. Thus the clinical effectiveness of propolis on infectious root canal disinfection was evaluated.Results:1.Propolis aqueous solution showed the good inhibiting effect on growth of Pi, Fn and mixture of Pi and Fn. MBC value are respectively 0.025%, 0.05% and 0.05%. The inhibitory effect of propolis become better with increasing of concentration.2.RGR of HPLF changed with the different concentration in propolis groups (concentration ranging from 0.1% to 0.6% ) and calcium(concentration ranging from 1% to 10% ) hydroxide groups. Cytotoxicity was showed more obvious by increasing concentration,but toxicity class of all medicines were below grade two. There was no statistical difference between propolis groups and calcium hydroxide groups(P>0.05).The cytotoxicity of 0.1% propolis and 1% calcium hydroxide were less than that of other groups, and there was significant statistical difference(P<0.01).3.0.1% Propolis and 0.4% propolis and calcium hydroxide all could improve clinical symptom of patients with chronic apical parodontitis. The statistical results in respects of pain, sensitive to percussion, swelling and sinus relieve indicated that there were significant difference among all the groups (P<0.01). The statistical results in respect of visit frequency showed the disinfection effect of 0.4% propolis was better than that of 0.1% propolis and calcium hydroxide(P<0.05).While there was no statistical difference between 0.1% propolis group and calcium hydroxide group(P>0.05). The culture results of bacteria samples showed bacterial amount all obviously decreased after preparation of root canals and after disinfection. For the same group, there were statistical difference of bacterial amount among different times of examination(P<0.05). For the same time of examination , there was no statistical difference among three groups(P>0.05)Conclusion:1.Propolis aqueous solution showed the good inhibiting effect on growth of Pi, Fn and mixture of Pi and Fn, which indicated propolis has good bacteriostasis effect on oral anaerobium.2.Propolis and calcium hydroxide has low cytotoxicity for HPLF. 0.1%propolis and 1%calcium hydroxide has the least toxicity. 3.0.1% Propolis and 0.4% propolis and calcium hydroxide all could improve clinical symptom of patients with chronic apical parodontitis. The results from bacteria culture and test under microscope of film preparation indicated they can kill bacteria in infectious root canals. The statistical results showed 0.4% propolis has better value of application in clinic root canal disinfection.