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Objective:To evaluate the effect of semiconductor lasers irradiation after routine root canal preparation on root cannal seal.Methods:60 Single-rooted freshly extracted human teeth were randomly divided into 6 groups(n=10).The crowns were removed at the cementoenamel junction and the roots were endodontically prepared with conventional methods.The roots in groups A and B were irradiated with 1 W semiconductor laser for 20 s,in group C and D were ultrasonically washed for 1 min,in group E and F without any treatment were used as the controls.Then all the roots were filled by vertical condensation of warm gutta-percha.The root cannal seal was evaluated with microleakage measurement.The data was analyzed by ANOVA.The teeth of group B,D and F were sectioned and examined under scanning electron microscope(SEM).Results:The microleakage(mm) of group A,C and E was 1.70±0.82,2.02±0.40 and 4.56±2.72 respectively(A vs E,P0.05).SEM observation showed the melting,narrowness or closure of most dentinal tubules in group B,past and/or gutta-percha in the most dentinal tubules of group D.Conclusion:Semiconductor laser irradiation prior to root cannal filling can promote the effects of cannal seal.
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Objective: To examine the microbial flora within the root canals with failed root canal therapy by PCR test, to identify detection rate of bacteria and the predominant bacteria species, and to determine the association of the various species with clinical features. Methods: Forty roots with failed root canal therapy were selected for this study. According to clinical features the roots were divided into three groups: pain, fistula and symptomless. After removal of the root filling material, the microbial samples were taken from the canal and detected by PCR test. Results: The microbial flora within root canals of teeth with failed root canal therapy was found to be mixed, six kinds of bacteria were detected. Enterococcus faecalis was the most commonly recovered bacteria species. Significant associations were observed between Prevotella nigrescens and pain, while dependablity was observed between Actinomyces israelii and fistula. Conclusion: The main cause of root canal treatment failure is the persistent microorganisms. The composition of bacteria in teeth with failed root canal therapy has its own specificity.
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Objective:To study the effect of insulin therapy on glucose concentration in saliva in patients with diabetes mellitus(DM), and to study the relationship between blood glucose level and salivary glucose level.Methods: Glucose concentration in blood and in unstimulated mixed saliva was measured with Beckman SYNCHRON CX7 system in 40 DM patients before and after insulin therapy.Results:The average value(mmol/L) of salivary glucose concentration before and after insulin therapy was 2.081?0.287 and 1.571? 0.193 respectively (P
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Objective: To study the effect of pulsed Nd:YAG laser irradiation combined with acidulated phosphate fluorid (APF) on the acid resistance of human dental enamel. Methods: Enamel samples were prepared from 192 caries-free extracted teeth. The smooth surface and pits and fissures were treated with 12 3 g/L APF for 4 minutes after 100,150 or 200 mJ pulsed Nd:YAG laser irradiation. Then the teeth were put into 12.3 g/L of artificial caries inducing solution (acid solution) for 1,5,10 or 24 h respectively. The control teeth were treated with APF only. The amount of calcium dissolved in the solution was determined with an atomic absorption spectrophotometer and the depth of artificial caries was measured with polarized microscope. Results: The amount of calcium dissolved in the acid solution was significantly less in the groups with laser treatment than that in those without laser treatment (P
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Objective: To analyse the level of glucose concentration in saliva and to study the relationship between the level of blood glucose and that of salivary glucose.Methods: Blood glucose level and the glucose concentration in unstimulated mixed saliva taken from testee were measured with Beckman SYNCHRON CX7 System in 60 patients with diabetes mellitus and 60 healthy subjects. Results: The average value of salivary glucose concentration in experimental group was (1.950?0.179) mmol/L, that in control group was (0.953?0.124) mmol/L(P
