The Preliminary Study Of The Aqueous Extract Of Chinese Nutgall As Root Canal Sealer

The aim of canal obturation is to completely fill the root canal system by a material which has persistent bacteriostatic action and activates repair mechanism of host and to segregate root canals from tissues of periapex, preventing reinfection and encouraging healing of periapical pathological lesion.Nowadays, Many kinds of root canal sealers in clinic can not completely fulfil the ideal requirement. Chinese nutgall, as naturally traditional chinese medicine, is relatively safe and innoxious. Its main ingredient, tannic acid has lots of effects, such as combining organic matters to obstruct dentinal tubules and inhibiting the growth of many kinds of bacteria which cause caries and periodontal diseases and infection in root canals. It has not been reported that whether Chinese nutgall can be used as root canal sealers. Therefore in this research, aqueous extract of Chinese nutgall was used as the root canal sealer in order to observe its histocompatibility, the quality of the apical sealing, the function of inhibiting bacteria and the therapeutic effect of experimental apical periodontitis in animal model. 1. The experimental study of histocompatibility of Chinese nutgall as root canal sealerTo observe the histocompatibility of Chinese nutgall as root canal sealer, subcutaneouly implant method was used. The experiment was divided into 4 groups. Group 1: Chinese nutgall, Group 2: AH Plus, Group 3: root canal sealers containing formaldehyde, Group 4: blank control. 5 rabbits were killed at the period of 1,4 and 12 week after implantation. After ordinary prepared sample, the amount of inflammatory cells and the thickness of fibrous membrane of the tissues around the implant button were observed. The results showed that the inflammatory response of the tissue around the implant button gradually decreased with time. The rate of descent of Chinese nutgall root canal sealer was greatest and the tissue inflammatory reaction was significantly lower than the group of AH Plus at the fourth week(P<0.05).It had not significant difference with blank control group(P>0.05).The group of AH Plus had still some inflammatory response at the 12th week and it had significant difference compared with blank control group(P<0.05). The group of root canal sealer containing formaldehyde was the slowest one which inflammatory response descended and there was still heavy at the 12th week. Therefore we may concluded that Chinese nutgall as root canal sealers has good histocompatibility.2. The experiment of inhibiting bacteria of Chinese nutgall as root canal sealer in vitroThe effect of inhibiting bacteria of Chinese nutgall and other three root canal sealers commonly used in clinic(root canal sealer consisting of formaldehyde,AH Plus,Vitapex)was tested by measuring disinfecting diameter. The chosen bacteria included the anaerobes (Fusobacterium nucleatum,Actinomyces naeslundii) and the aerobic bacteria(α-streptococcus hemolyticus,Staphylococcus aureus). The results showed that the best group of disinfecting action was root filling material containing of formaldehyde, the second one was Chinese nutgall root filling material; and the third one was Vitapex, while AH Plus has no disinfecting effect. Each group of experiment had noticeable difference(P<0.05) compared with blank control group except for the group AH Plus(P>0.05). Both of the group of Chinese nutgall and root canal sealer containing formaldehyde had noticeable differences compared with group Vitapex(P<0.05). It had no noticeable differences between group of Chinese nutgall and root canal sealer containing of formaldehyde group(P>0.05).3. The experiment of the ability of apical sealing of Chinese nutgall as root canal sealer in vitroThe ability of the apical sealing of chinese nutgall and other two commonly used root canal sealers in clinic(root canal sealer containing formaldehyde,AH Plus)were observed by dyeing permeation and SEM. The results showed that the AH Plus is the best, and the following one is Chinese nutgall. but there were no noticeable differences between two groups(P>0.05). The worst one is root canal sealer containing formaldehyde. It suggests that Chinese nutgall as root canal sealer has good ability of apical sealing.4. The animal study of experimental apical periodontitis treated with Chinese nutgall as root canal sealerThe dog's experimental apical periodontitis was set up by dental pulp opening after three months. The experiment divided into 4 groups designed by latin square randomly (Chinese nutgall, AH Plus, root canal sealer containing formaldehyde and blank control) .The chosen experimental teeth were anterior teeth, from left canine to right canine of upper and lower jaws. The root canal therapies were conducted with different root canal sealers, and blank control had no obturation. After 3 months, the dogs were killed and all samples were obtained by preparation paraffin section and HE staining. The results showed that inflammatory responses of apex of each experimental group had noticeable difference compared with blank control group(P<0.05). The groupl of AH Plus had lightest inflammatory response, the following one was Chinese nutgall, but there were no noticeable differences between these two groups(P>0.05). The most severe group was root canal sealer containing formaldehyde, and it had noticeable differences compared with AH Plus and Chinese nutgall as root canal sealer(P<0.05). Therefore it can be concluded that Chinese nutgall had the same effect with AH Plus as root canal sealer in short period. It still need longer period to examine its long-term effect.