Essentials of Statistics in Dental Research: Part 1.

Dental professionals review articles in scientific dental journals to be informed about progress in the field and to remain up to date in the dental literature. As a general rule, knowing the basic statistical concepts such as study design, hypothesis testing, confidence interval, significance level, effect size, and sample size and power can help readers to better understand the whole concept of an article. Reviews of statistical methodology in published papers of well-established dental journals concluded that the majority of the papers contained statistical errors. Inappropriate use of statistical methods may lead to incorrect conclusions and a waste of valuable resources. The aim of this paper is to provide an overview on some implications of the statistical concepts and recommendations for avoiding statistical errors in dental research.

Prehospital emergency management of avulsed permanent teeth: Knowledge and attitude of schoolteachers.

Context: Tooth avulsion is one of the most serious dental emergencies in children. Often these injuries occur in school and, therefore, the knowledge of schoolteachers regarding the appropriate measures to be taken immediately after tooth avulsion is crucial to good prognosis. Aims: The purpose of the present study was to evaluate schoolteachers' knowledge and attitudes regarding immediate management of avulsed teeth in children. Materials and Methods: A total of 177 teachers from seven schools of Garhshankar town, Hoshiarpur District, Punjab, India, formed the sample of the study. A self-administered questionnaire consisting of 16 questions was used to assess the knowledge and attitudes of schoolteachers about tooth avulsion and its management. Statistical Analysis: The chi-square test and one-way analysis of variance (ANOVA) were used for analysis. Pair-wise comparison was done using Tukey's honestly significant difference (HSD) test. P≤0.05 was considered to be statistically significant. Results: Markedly low knowledge levels were noted among the schoolteachers. The mean knowledge score was 5 (of a maximum possible score of 10). Only 0.6% of the teachers answered correctly that they would use milk as a transport medium. The number of correct responses was not affected by previous experience with tooth avulsion, sex, educational level, teaching experience, or teacher training. Overall, 85.9% of teachers showed a positive attitude towards this campaign. Conclusions: Knowledge regarding emergency management of dental trauma is poor amongst schoolteachers. Therefore, we suggest that orientation to management of avulsed tooth be part of the teacher training education.

Effect of varying height and taper on the fatigue performance of full-coverage TESCERA ATL ceromer crowns

This study assessed the effects of varying crown preparation heights and tapers on the fatigue performance of full-coverage TESCERAATL ceromer crowns. Seven cobalt-chromium dies were fabricated to receive full-coverage crowns. The first four dies had heights measured at 4.0, 3.5, 3.0 and 2.5 mm from the lingual wall, each with a 6° taper and assigned as groups 1 to 4 respectively. The last three dies had tapers measured as 14°, 18° and 22°, with heights fixed at 4 mm and assigned as groups 5 to 7 respectively. All other variables were kept constant. Ten full-coverage TESCERAATL crowns were fabricated for each of the 7 dies, All 70 crowns were cemented with zinc phosphate onto their respective cobalt-chromium dies and secured on a metal repositioning jig, which standardized the load application point. The assembled specimens were subjected to a unidirectional cyclic loading of 210 N at a frequency of 4 Hz sequentially from group I to 7. Number of cycles to failure for each specimen was recorded once catastrophic failure occurred. Two electrical resistance strain gauges were used to indicate preliminary failure. One-way Analysis of Variance [ANOVA] and post hoc Tukey tests were conducted for groups 1-4 and 5-7. There is a statistical difference between groups 1-4 and 5-7 [p<0.05]. The means and standard deviations for the first four groups were 4.255 x105 [ +/- 0.486], 4.295 x l 05 [ +/- 0.689], 4.264 x 105 [ +/- 0.567] and 2.406 x 105 [ +/- 0.656] cycles to failure respectively. The means and standard deviations of groups 5, 6 and 7 were 4.12 x105 [ +/- 0.401], 3.583 x105 [ +/- 0.352] and 3.016 x105 [ +/- 0.246] cycles to failure respectively. Fatigue performance remains unaffected by reductions in height up to a particular value [3.0mm] and then suddenly drops. Fatigue performance follows a linear relationship with changes in taper, with fatigue life gradually decreasing with an increase in taper