| Objective:Generally speaking,Chronic periapical disease will gradually heal after root canal treatment,but there are a few cases that inflammatory secretions and the periapical tissue swelling repeatedly were still discovered after several conventional root canal treatment,even leading to the tooth loss and alveolar bone defect,which is called refractory periapical periodontitis.The etiology is complex and the course of disease is long.That is why refractory periapical periodontitis who has a disadvantageous impact on the quality of life of patients is troublesome in clinical medicine.Enterococcus faecalis is considered the main pathogens of refractory periapical periodontitis.Enterococcus faecalis is a Gram-positive facultative anaerobic bacteria,belongs to Enterococcus spp,which can permeate through the lateral branch of dentinal tubules.It has strong drug resistance and strong alkali resistance,and can survive in the harsh conditions of chronic hunger.Enterococcus faecalis can not be eliminated completely by the traditional methods such as conventional mechanic and chemical preparation,root canal irrigation.Then root canal disinfection becomes an indispensable step because of the complexity of the root canal system.So it has great clinical significance to find a new root canal disinfectant which is safe and effective and be able to kill Enterococcus faecalis in the infected root canal to improve cure rate of refractory periapical periodontitis.In recent years,the biodegradable magnesium-based metal has been widely recognized as a new biomedical material.According to the relevant studies,magnesium and magnesium alloys have good antibacterial property to Enterococcus faecalis and Candida albicans because of their biodegradable properties.This article will use pure Mg and Mg-Cu alloys as a kind of new disinfection materials to evaluate the antibacterial efficacy of them using an vitro model infected by Enterococcus Faecalis,aiming to do some initial exploration for the application of biodegradable magnesium-based metal in Dentistry.Materials and Methods: Eighty extracted human single-rooted mandibular premolars were collected and canal prepared.The crowns and roots of the teeth were removed.After cleaning and sterilization,the root canals were infected with E.faecalis to establish E.faecalis infected models.Then the specimens were divided randomly into three experiment groups(A、B、C)and a control group(D),with twenty teeth in each group.All root canals were treated with different intracanal medicament as below: group A with magnesium(Mg)paste plus sterile physiological saline;group B with Mg-Cu alloys paste plus sterile physiological saline;group C with calcium hydroxide paste plus sterile physiological saline;group D with sterile physiological saline only.Then the canals were incubated at 37℃.After 24 hours and 7 days,ten microbiological samples were collected from the root canals from each group,and were incubated in common nutrient agar for 48 hours,and the colony of bacteria was counted(CFU/ml).Result: No statistically significant difference were observed among the groups of A(7.585±0.1082),B(7.643±0.1419),C(7.612±0.1237)and D(7.638±0.1147)before the experiment(P>0.05).24 hours after root canal disinfection,the number of E.Faecalis in groups of A(2.359±0.1508),B(2.518±0.2364)and C(2.560±0.1287)were obviously reduced.No significant difference was found between A and B(P>0.05).Seven days after root canal treatment,the number of E.Faecalis of all experimental groups(A:2.357±0.1696,B: 2.343±0.2274,C:2.478±0.1766)further decreased(P<0.05).And no significant difference was found among the three treatment groups(P>0.05).Conclusions: The results suggested that Mg and Mg-Cu alloys paste plus sterile physiological saline are all effective for eliminating E.faecalis in root canal specimens.Further studies are needed to confirm the value of Mg and Mg-Cu alloys in clinical treatment. |
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