| BackgroundPeriodontitis is one of the common diseases of mankind, and the pathogenic factors of this chronic disease are always complicated. Periodontitis can cause gingival inflammation, periodontal pocket formation and alveolar bone resorption, as a result the affected teeth become mobility and eventually fall off. The basic treatment of parodontopathy is cleaning the local inducible factors which can decrease the pathogenic bacteria and improve the local environment, and such kind of treatment has been proved effective for a long time. However, some of the periodontal structures and some of the patients are not sensitive to this treatment, and one of the causes is that the pathogenes are still active in local periodontal structures. Systemic medication with antibiotics can be effective, but long term systemic medication can lead to the imbalance of bacteria floras, drug-resistant strains and a variety of side effects, and thus it can not be used as routine treatment. Local delivery of medicines in periodontal tissues is able to directly and immediately inhibit or kill the pathogenic microorganisms, and thus to control the periodontal inflammation, reduce the destruction of the periodontal tissues, decrease the bacteria plaques, and facilitate the reconstruction of the damaged tissues. With the development of modern pharmacy, local delivery of low-release medicines has been used in the treatment of parodontopathy. In addition to the advantage of local delivery of medicines, the special slow-release design of the novel pharmaceutical preparations can also prolong the acting time of the medicines in local periodontal tissues, and the medicine concentration in infected local periodontal tissues can be sustained for a long time, therefore blood concentration peaks can be avoided, medication times can be decreased, and also a better treatment effect can be achieved. ObjectiveAt first,the study is to identify environmental factor which is unfavourable to the compound sustained-release gum suppositories by the stress condition test,and thus to provide theoretical support for designing and doing accelerated stable test and long term stable test of the gum suppositories,at last to provide scientific evidence for producing, package, storage , transportation ,determining of the expiration date of the gum suppositories. Then an experimental animal model of periodontitis will be established to study the effect of the gum suppositories on the periodontium and the level of aspartate aminotransferase in gingival cervical fluid(GCF-AST) of SD rats , Ultimately to sure the treatment effect of the gum suppositories on experimental rats, and to form the basis of clinical experiments..Materials and methods1. In an air tight ,brown and constant-humidity glass bottle ,20 suppositories was Spread in a flat plate on the sealing coat under which saturated sodium chloride solution was contained(humidity75%). In another air tight ,brown and constant-humidity glass bottle ,20 suppositories was Spread in a flat plate on the sealing coat under which saturated kalium nitrate solution was contained(humidity92.5%). 20 suppositories were Spread in a flat plate in the baking oven in which temperature had been set 40℃. other 20 suppositories were Spread in a flat plate in the baking oven in which temperature had been set 60℃. 20 suppositories were Spread in a flat plate ,were exposed to 4500 Lx±500 Lx of light intensity.All suppositories were tested for 10days in the above-mentioned condition, and all suppositories were detected on such indexes as character, appearance, hydroscopicity, the content of ornidazole and pefloxacin, dissolution rate at prior-experiment and 5d and 10d after experiment respectively.2. 3 batchs of suppositories were sealed in 3 brown glass bottles respectively,and were tested for six months under conditions of 30℃,RH 65%. All suppositories were detected in the first,second,third,sixth month in the ditto indices. 3 batchs of suppositories were sealed in 3 brown glass bottles respectively,and were tested for eighteen months under conditions of 25℃,RH60%. All suppositories were detected in the third,sixth,ninth, twelfth,sixteenth,eighteenth month in the ditto indices.3. 90 SD rats(12 months of age) were randomly classified as A,B,C,D and E group.B,C,D and E group were ligated with thin thread at neck of selected tooth,and provided with high glucose food and drink to induce periodontitis animal model.The sustained-release periodontal suppository of ornidazole and pefloxacin was used to treat E group,and Yakang(metronidazol stilus) was used to treat D group. All groups'periodontal indices were measured and the effect of therapies were evaluated.Results1. Under conditions of high humidity(25℃, RH 92.5 %,75 % ) , high temperature(40,60℃),the irradiation of strong light(4500±500)Lx of 10days , the content of medicine was 95～105% of marked quantity, dissolution rate of ornidazole was 10～20%,55～65% and 95% of marked quantity at 1,5,13 hours respectively,dissolution rate of pefloxacin was 20～30%,40～50% and 95% of marked quantity at 1,5,13 hours respectively. after moisture absorption ,weight increasing of the medicine was less than 5% .At appearance, after high humidity test of 10days and high temperature test of 10days respectively,itS'appearance still were buff suppositories; and after the irradiation of strong light of 10days, itS'colour changed from buff to brown.2. after accelerated stable test of six months and long-term stable test of eighteen months respectively, itS'appearance still were buff suppositories; the content of medicine was 95～105% of marked quantity, dissolution rate of ornidazole was 10～20%,55～65% and 95% of marked quantity at 1,5,13 hours respectively,dissolution rate of pefloxacin was 20～30%,40～50% and 95% of marked quantity at 1,5,13 hours respectively.3. 8 weeks after the modeling, all the periodontal specifications showed significant changes, and there was a distinctive difference (p<0.01) in comparison with the normal group, suggesting a successful modeling of the SD rats. At 10d after treatment E group and D group exhibited significant differences from prior-treatment in all periodontal indices and GCF-AST(P<0.01) ,and E group exhibited nonsignificant differences from D group(P>0.01). At 20d after treatment E group and D group exhibited nonsignificant differences from 10d after treatment(P>0.01). Conclusions1. slow-release compound suppositories of ornidazole and pefloxacin mesylate should be stored in cool place and protected from strong light.2. slow-release compound suppositories of ornidazole and pefloxacin mesylate have a good stability, it's expiration date is above eighteen months.3. The compound ornidazole and pefloxacinmesylate sustained-release gum suppository is effective in treating periodontitis, especially in reducing the inflammation and destruction of periodontal tissues; GCF-AST can be Considered as objective indices for the therapeutic effect of periodontitis of rats.
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