0.05).There was significant difference at 6 h,24 h and 1 week(P

BACKGROUND:The post space cleaning using ultrasonic file can improve the bonding strength of fiber postscemented with the self-adhesive resin cement, but the effect on apical sealing ability is stil unclear. OBJECTIVE:To evaluate the effect of the post space cleaning using ultrasonic file on apical microleakage fol owing treatment with two kinds of root canal sealers at two different residual lengths of root canal fil ing. METHODS:Eighty extracted human maxil ary anterior teeth with single-rooted canal were selected, and equivalently randomized into groups A and B (n=40 per group), fol owed by fil ed with Cortisomol or AH-plus, respectively. Groups A and B were randomly subdivided into four groups according to the residual length of root canal fil ing and with or without ultrasonic cleaning (n=10 per group):A1, B1 groups:residual 5 mm, no ultrasonic cleaning;A2, B2 groups:residual 5 mm, ultrasonic cleaning;A3, B3 groups:residual 3 mm, no ultrasonic cleaning;A4, B4 groups:residual 3 mm, ultrasonic cleaning. Subsequently, the apical microleakage was measured using dye method and transparent specimen technique under stereomicroscope. RESULTS AND CONCLUSION:The apical microleakage of each group was as fol ows:A1 (0.73±0.21) mm, A2 (1.37±0.55) mm, A3 (1.18±0.36) mm, A4 (2.05±0.62) mm, B1 (0.34±0.18) mm, B2 (0.47±0.14) mm, B3 (0.59±0.23) mm, B4 (1.39±0.50) mm. The three-factor analysis of variance revealed that the ultrasonic cleaning, root canal sealers and residual length of root canal fil ing al had a significant effects on the apical microleakage (P<0.05), and there were significant differences in the apical microleakage between groups A1 and A2, groups A3 and A4, groups B3 and B4, groups A2 and A4, groups B2 and B4 (P<0.05). These results indicate that the ultrasonic cleaning increases the apical microleakage fol owing the use of Cortisomol at 5 and 3 mm residual length, as wel as the use of AH-Plus at 3 mm residual length. Moreover, for the same root canal sealer, the longer residual length of root canal fil ing indicates, the less microleakage after ultrasonic cleaning.

To evaluate the clinical effects of rotary nickel-titanium instruments Mtwo in root canal therapy in the aged patients. Using step-back technique,80 teeth with pulpal and periapical involvement were instrumented by Mtwo in the M group, and by K file in the K group. Mtwo could keep the original curvature and flow of the root canals. No transportation, apical blockage, ledge or perforation was found in the M group. There was more complications in the K group than in the M group.The operative time was shorter and posttreatment pain seldom occurred in the M group. With rotary NiTi instruments Mtwo for seniles' root canals treatment, root canals can be prepared effectively and quickly,and is worth of clinical application.

Objective: To explore rational drug usage for periodontitis treatment through a comparative study of the efficacy of four kinds of drugs on the experimental periodontitis. Methods: 126 Wistar rats,10 randomly selected as normal control group, the other 116 were modeled by using local wire ligation and systemic prednisolone acetate injection. Successful animal models were randomly divided into model control group and berberine hydrochloride, minocycline hydrochloride, ginsenoside Rg-1 and transforming growth factor-β1 treatment groups, which were treated with each kind of medicine separately and were killed at the end of 1, 2, 4 weekend. Detected IL-1β, TNF-α, IL-6, BGP levels by immunohistochemical SABC assay. Results: IL-1β, TNF-α, IL-6 of the treatment groups were lower and BGP was higher than model control group(P<0.05).Among them, the role of berberine hydrochloride to reduce IL-1β and TNF-α was the best. The role of minocycline hydrochloride to reduce IL-6 was the fastest. The role of transforming growth factor-β1 to increase BGP was the fastest. The role of ginsenoside Rg-1 to increase BGP was more lasting and better follow-up. Berberine and ginsenoside Rg-1 reduced IL-1β, TNF-α, IL-6 and increased BGP at the same time. Conclusion: The treatment of minocycline hydrochloride and transforming growth factor-β1 are quick. Berberine and ginsenoside Rg-1, particularly berberine have the advantage of multi-targets' role.

Objective To observe the effects of Er-YAG and surgical resection in the treatment of oral cav-ity mucous cyst. Methods A total of 63 patients with oral cavity mucous cyst ,selected in our hospital from March 2013 to May 2014,were divided into control group(n=31)and experimental group(n=32)based on dif-ferent therapies. The oral cavity mucous cysts in the experimental group and the control group were treated with Er-YAG and surgical resection ,respectively. The two groups were compared in terms of therapeutic effect. Results The cure rate in the two groups had no significant difference (P>0.05). The operation time in the experiment group was significantly shorter than the control group(P<0.05). In the experiment group,the incidence of intra-operative blood loss,postoperative edema and postoperative scarring were significantly lower than those of the con-trol group(P<0.05),but the two-year recurrence rate in the two groups had no significant difference(P>0.05). The SAS scores had no significant difference between the two groups at 1 week after operation (P > 0.05),but they were significantly higher in the experiment group than in the control group before operation and 3 days after op-eration(P < 0.05). In HAD emotional determination,the numbers of patients who had the manifestation of anxi-ety and depression in the experiment group were smaller than control group before operation and 3 days after opera-tion(P<0.05),but there was no significantly difference between the two groups at 1 week after operation(P >0.05). Conclusions The curative effect of Er-YAG in the treatment of oral mucous cysts is close to that by the conventional surgery,but the former is advantageous for easier operation,less postoperative complications and alle-viation of patientspsychology pressure,worthy of clinical spreading.

BACKGROUND: Oyster shell has been recently reported as a new root canal filling material; therefore, it needs primary biological evaluation, i.e., cytotoxicity test and genotoxicity test, before clinical application. OBJECTIVE: To evaluate cytotoxicity and genotoxicity of oyster shell powder. DESIGN, TIME AND SETTING: A contrast observational study was performed at the Materials Laboratory, School of Stomatology of Peking University from April to July 2008. MATERIALS: Oyster shell powder was provided by Institute of Oceanology, Chinese Academy of Sciences; L929 cell strain and Salmonella typhimurium TA97, TA98, TA100, and TA102 were provided by the National Institute for the Control of Pharmaceutical and Biological Products. METHODS: Oyster shell diffusion was prepared based on the times of 0.5, 1, and 2. According to the standards of biological evaluation of dental materials, the cytotoxity and genotoxicity of oyster shell were evaluated with molecule filter test and Ames test. MAIN OUTCOME MEASURES: Fading area of the film induced by succinic dehydrogenase and amount of spontaneous revertants. RESULTS: After 2 hours, the results indicated that fading area of the film in the experimental group was the same as negative control, i.e., fading was not found in the film, and cytotoxicity was grade 0. After 24 hours, diameter of non-stained film was 1.0-2.0 mm, fading area was 1-3 mm2, and cytotoxicity was grade 1, suggesting that the material had light cytotoxity that was still qualified. The spontaneous revertant test indicated that the mutagenicity of experimental groups was no more than 2 times of the control groups, suggesting there was no dose-dependence. CONCLUSION: Oyster shell powder has no cytotoxicity and genotoxicity on the organism.

0.05). While the length of penetration had statistical differences between 0.02 tapered angle group and 0.06 tapered angle group (P

Objective: To compare and analyze the antimicrobial efficacy of three different mechanical preparation techniques in single infected root canals. Methods; Forty-five single root canals with chronic periapical periodontitis were selected. The specimens were divided into three groups randomly, 15 root canals per group. Croup A: preparation with stainless steel K-files (step-back technique), Croup B: preparation with HERO 642 NiTi rotary files (crown-down technique) and Group C: preparation with Mtwo NiTi rotary files ( modified crown-down technique). The sterile normal saline was used as irrigation. Samples were taken before and after canal preparation. The difference of CFU was calculated as well as the bacterial species. Results; All groups were effective to reduce bacteria within the infected root canals greatly(P<0.01). Croup A and Group C were statistically better than Group B(P<0.05). Group A was more effective than Group C but there was no statistically difference between them(P>0.05). Conclusion; Mechanical preparation can greatly reduce the intracanal bacteria, but can not obtain bacteria-free canals. The mechanical preparation must be aided by chemical irrigation to improve the success of root canal therapy.

Objective:To observe the effect of “bulk-fill”flowable resin in filling deep wedge-shaped defects.Methods:50 pa-tients with totally 85 pairs of premolars with deep wedge-shaped defects(depth >2 mm)were included.Each pair of the defects was randomly divided into the test group and the control group,the defects were treated by “bulk-fill”flowable resin with single cure tech-nique and conventional flowable resin with incremental layering technique respectively,the tooth sensitive rate 1 week after filling,the filling failure rate,the edge coloring and secondary caries rate 2 years after filling of the 2 groups were compared.Results:There was no significant difference between the 2 groups in the sensitive rate 1 week after filling,the failure rate and the edge coloring and sec-ondary caries rate 2 years after filling(P >0.05).Conclusion:The “bulk-filled”flowable resin using single cure technique can ac-quire the same clinical effect as conventional flowable resin using incremental layering technique in filling deep wedge-shaped defects.

Objective:To observe the color change of tooth i nduced by hydrogen peroxide gel. Method:12 extracted teeth were randomly assigned to two groups (n=6) and treated with 350 g/L and 75 g/L hy drogen peroxide gel respectively. One of the 6 samples in each group was used as the control. The bleaching gel was placed onto the enamel surface of the sample s. In 350 g/L gel group digital photographs were taken just before,10 and 30 min after the process, in 75 g/L gel group digital photographs were taken before an d 1.5?N(N=0,1,2,3,4,5,6,7) hours after the process respectively. All photograph s were taken at the same illuminating conditions and photographic parameters wer e analyzed with Photoshop7.0 software. Results:10.5 h after trea tment in the 75 g/L gel group L *, a * and b * values on the teeth surface were in creased(+) or decreased(-) by +4.5,-1.4 and -0.5,those on the inner sections 2.7 ,-1.0 and -0.8,respectively. 30 min after treatment in the 350 g/L gel group L *, a * and b * values on the teeth surfaces were increased(+) or decreased (-) by +1.9,-0.6 and 0,those on the inner sections +0.4,-0.4 and -0.6,respectively. Conclusion:Effective bleaching effect may be obtained in 10~30 min b y 75 g/L or 350 g/L hydrogen peroxide gel on teeth surface and in inner dentin. 75 g/L hydrogen peroxide bleaching gel may produce more reliable and save effect than 350 g/L.