in vitro evaluation of the influence of concentration and duration of exposure on the antimicrobial efficacy of sodium hypochlorite on enterococcus faecalis

To evaluate, in vitro, the effectiveness of different concentrations of sodium hypochlorite [NaOCl] [0.5%, 1.0%, 2.5% and 5.25% w/v] in the elimination of Enterococcus faecalis E10e. E. faecalis E10e was grown overnight and allowed to grow until the 'mid-exponential' phase. 0.2 ml of the inoculum that was then transferred into 9.8 ml of NaOCl solution. One ml samples were removed and poured in 9 ml of sodium thiosulphate [Na[2]S[2]O[3]] solution [neutralisation] after 30 sec, 1 min, 2 min, 5 min, 10 min and 30 min. Serial dilution of each neutralised solution was carried out to give a dilution factor of 10-6. Subsequently, 0.02 ml of each dilution was plated onto an agar plate, and then incubated at 37[degree sign]C in an aerobic incubator for 24 hrs. The number of viable colonies [Colony Forming Units / ml] was determined for each plate. The results showed that 5.25% NaOCl was the most effective irrigant assessed, killing 100% of bacterial cells in 2 min. However, the time required by 2.5%, 1.0% and 0.5% concentrations was 5 min, 10 min and 30 min, respectively. There was a statistically significant difference between NaOCl concentrations with respect to the mean number of viable counts recovered, with 5.25% NaOCl being the most effective irrigant assessed. There was a strong curvilinear relationship between NaOCl concentrations and time taken to attain zero viable counts [100% killing]

relationship between dental anxiety and reported dental treatment experience in children aged 11 to 14 years

The aim of the study was to determine the influence of reported dental experience on dental anxiety in children aged 11-14 years in Liverpool, United Kingdom. A total 366 children completed a two-part questionnaire. The first part invited the children to record which dental procedures they had experienced. These procedures were the same as those included in the Modified Child Dental Anxiety Scale, which formed the second part of the questionnaire. The scale consisted of eight questions, which invited the children to rate their anxiety about a variety of dental procedures, including going to the dentist in general, a dental examination, a scale and polish, local anaesthesia, dental restoration, dental extraction, dental treatment under general anaesthesia and dental treatment under inhalation sedation. The Modified Child Dental Anxiety Scale allowed the children to report on a five point Likert scale about how relaxed or worried they were for each of these scenarios. Cross-tabulation and t-tests were used to determine the relationship between dental anxiety and reported dental experience. The significance level for the study was set at p<0.05. Females were found to have significantly higher [p<0.05] mean anxiety score [21.87] than males [18.90]. Children were significantly less anxious about specific items of dental treatment if they had experienced that particular form of treatment. In the study group of 366 children, 232 [63.4%] reported that they had experienced a dental filling had a mean anxiety score of 2.23, 105 [28.7%] children reported that they had not experienced a dental filling had a mean value for the dental filling item of 2.70. Females were found to be statistically more dentally anxious than males. Children who reported that they had experienced dental treatment and visited the dentist more frequently were significantly less anxious than those who reported infrequent visits