effect of CPP-ACP paste on shear bond strength of glass ionomer to dentine

CPP-ACP is one of the numerous materials which is used in dental hypersensitivity and works through changing Cagradient in tooth surface, besides glass ionomer is a selective material in restoring non -carious cervical lesions because of chemical bonding. In this study we evaluate the effect of CPP-ACO on shear bond strength of glass ionomer to dentine. In this experimental study, 40 third molar teeth were sectioned to obtain dentine with tubule orientation perpendicular to the surface. The specimens were divided into 4 groups [A to D].Groups A and B were treated with CPP-ACP paste for 60 min x 5 days. Groups A and C were treated with polyacrylic acid 10% for 20 min before glass ionomer adhesion. All specimens were bonded with glass ionomer. After 24 +/- 1 hours water storage, the bonded specimens were sectioned with universal testing machine. There was no significant effect in shear bond strength to dentine in groups except groups B.There was no significant effect in failaure pattern. Most of the failure patterns were adhesive mode. CPP-ACP application in dentine surface reduces the shear bond strength of glass ionomer except the preconditioning of dentine with polyacrylic acid 10%. Preconditioning in dentine surface nontreated with CPP-ACP paste, does not affect the shear bond strength of glass ionomer

Marginal adaptation of the three indirect crowns

Good marginal adaptation is a prerequisite for a successful crown restoration while the incidence of microleakage, caries, damage to the base teeth and periodontal diseases is facilitated when this criteria is not achieved. Therefore, the present study determined the marginal gap in the porcelain crowns compared to indirect composite restorations of GC Gradia and Signum. In this invitro experimental study, 30 impressions were taken in the similar conditions and randomly assigned to receive porcelain crowns [Noritake super porcelain Ex-3] or indirect composite crowns of GC Gradia and Signum when no fluid and porosity were noted on them. The crowns were fitted on the master metal die and assessed by the stereomicroscope after complete sitting and finishing line preparation. The assessments were carried out on 8 points 1mm from the finishing line [buccal, lingual, mesial, distal, mesiobuccal, distobucaal, mesiolingual and distolingual]. Then, 8 jigs were fabricated and total 240 readings were made. The values were converted to micron and the statistical comparisons were made using nonparametric Kruskal-wallis and Mann-whitney U tests. Marginal gap of porcelain crowns was29/08 +/- 9/38microm and 84/53 +/- 15/47microm on the lingual and disto lingual points andtheGC gradia indirect composite, was 43.63 +/- 13.40microm and 74.53 +/- 28.03microm on the distal and distolingual points as well as 39.08 +/- 17.68microm and 95.44 +/- 30.66microm on the distal and mesiolingual aspects of the Signum indirect composites respectively .No significant differences were noted between the three crowns brands on the mesial, distal, mesiobuccal, distobuccal, and mesiolingual aspects.only 3 points [buccal, lingual and disto lingual] had significant differences. Regarding clinically acceptable values of marginal gaps mentioned in the literature,porcelain jacket crowns and indirect composite crowns possesses the necessary criteria of marginal gap and can be successfully used for crown restorations

correlation between the students' and authorities' ratings for faculty evaluation in Shahid Beheshti School of Dentistry

The most complex type of evaluation is teacher assessment since its measures have low validity and accuracy. To solve the mentioned problem, using a multidimensional approach is suggested. In Shahid Beheshti School of Dentistry, faculty evaluation is performed through 5 sources: undergraduate students, postgraduate students, department chair, education vice chancellor and dean of the school. The present study has been launched to determine the correlation between the students' and managers' ratings for faculty evaluation in academic year of 2010-2011. In this cross sectional study, the questionnaires for faculty evaluation were delivered to the above mentioned 5 groups. Scores of each faculty member were calculated and Pearson coefficient of correlation was used to assess the correlation between the scores of five groups. In order to determine the effect of each group on the final score of teacher assessment, variance component ratio was calculated. Data were analyzed through SPSS software 11.5. The scores allocated to the faculty members by dean of the school showed a significant positive correlation with the education vice chancellor scores [r=0.612]. Correlations between the other groups were not statistically significant. Variance component ratio analysis showed that given the score weights were similar in all groups, postgraduate students had the maximum effect [50.89%] and education vice chancellor had the minimum effect [1.11%] on the variance of faculty evaluation scores. The results of this study showed that among the five evaluating groups, just the opinions of education vice chancellor and dean of the school about faculty members have a significant positive correlation

reliability of post graduate students' ratings for faculty evaluation in Shahid Beheshti dental school in academic year of 2009-2010

Evaluating of academic members on students assessment is a common kind of educational evaluation in most countries such as Iran. Since recognition of the strengths and weaknesses of this evaluation method has an important role in educational promotion, the present study was designed to assess the reliability of post graduate students' in faculty evaluation. This is a descriptive study which is performed on 70 post-graduate students. The faculty evaluation questionnaire, which is routinely used in dental school, consisted of 10 questions with point Likert scale was completed twice by students with one week interval. For intraobserver reliability determination, Weighted kappa and to determine interobserver reliability, generalized Weighted kappa were used. The reliability of total students in all fields was assessed using intra class coefficient. The data were analyzed through SPSS 11.5. Reliability of students in different departments showed no significant statistical difference [p=0.569]. The mean intraobserver reliability was 0.414 and the mean interobserver reliability was 0.297. The results showed that intraobserver reliability in cases were the initial score was best or worst was significantly higher than the cases were the initial score was good or moderate [p=0.034]. The highest intraobserver reliability was in the field of "creating motivation for further study and research" and the lowest reliability belonged to the field of [tolerance to critics and suggestions]. The results of this study showed that the reliability of post graduate students' ratings for faculty evaluation was not high