Assessing the effect of dental implants thread design on distribution of stress in impact loadings using three dimensional finite element method

Statement of Problem: Impacts and accidents are considered as the main factors in losing the teeth, so the analysis and design of the implants that they can be more resistant against impacts is very important. One of the important numerical methods having widespread application in various fields of engineering sciences is the finite element method. Among its wide applications, the study of distribution of power in complex structures can be noted

Objectives: The aim of this research was to assess the geometric effect and the type of implant thread on its performance; we also made an attempt to determine the created stress using finite element method

Materials and Methods: In this study, the three dimensional model of bone by using Cone Beam Computerized Tomography [CBCT] of the patient has been provided. The implants in this study are designed by Solid Works software. Loading is simulated in explicit dynamic, by struck of a rigid body with the speed of 1 mm/s to implant vertically and horizontally; and the maximum level of induced stress for the cortical and trabecular bone in the ANSYS Workbench software was calculated

Results: By considering the results of this study, it was identified that, among the designed samples, the maximum imposed stress in the cortical bone layer occurred in the first group [straight threads] and the maximum stress value in the trabecular bone layer and implant occurred in the second group [tapered threads]

Conclusions: Due to the limitations of this study, the implants with more depth thread, because of the increased contact surface of the implant with the bone, caused more stability; also, the implant with smaller thread and shorter pitch length caused more stress to the bone

[Critical thinking skills and critical thinking dispositions in freshmen and senior students of health care management]

Nowadays, experts introduce critical thinking as the main outcome of higher education and consider teaching "how to think" as the basis for learning. This study compares the critical thinking skills and critical thinking dispositions in freshmen and senior students of health care management. This descriptive cross-sectional study was performed on a sample of 60 freshmen and senior students of health care management. The data gathering tools included California critical thinking skills test, as well as California critical thinking dispositions inventory. Data was analyzed by SPSS software using descriptive statistics, T-test, and Chi[2]. The mean and standard deviation of critical thinking skills total score in freshmen and senior students was respectively 11.55 +/- 2.18 and 11.21 +/- 2.59, which was in the normal limit for both. There was no significant difference between the freshmen and senior students' score patterns. Considering critical thinking disposition total score, the mean and standard deviation in freshmen, was 282.37 +/- 27.93 and in senior students was 289.64 +/- 21.13. There was a significant difference between the score pattern of critical thinking disposition in freshmen and senior students. The scores of senior students were higher than freshmen scores. The total score of critical thinking skills achieved by students was in a normal limit. Also, the total score of critical thinking dispositions revealed the students' positive tendency. But, with regard to the reported scores from other similar schools of the world, administrators and teachers should pay more attention to their educational planning in developing cultivating critical thinking skills

effect of two disinfectant solutions on dimensional changes of impression materials

The purpose of this invitro study was to investigate the effect of disinfectants on dimensional changes of Speedex impression material. Thirty impressions were taken by Speedex impression material from laboratory stainless steel model. 20 impressions were disinfected, 10 using%5.25 sodium hypochlorite and using 2% Acid glutaraldehyde for 10 minutes. And 10 impressions served as non-disinfected as control group. Impressions were then rinsed under the cold water and stored in room temperature for 20 minutes in disinfected group and 30 minutes in nondisinfected group. Casts were made using type IV gypsum. The height and diameters of dies and the distance between the dies were measured in the three groups. Statistical analysis of the data was done using ANOVA and t- test. The height of the die in the sodium hypochlorite group increased and in the glutaraldehyde group decreased vs control group. The diameter of the die in both sodium chlorite and glutaradehyde group had some increase vs control group. The distance between the dies decreased in both groups vs control group. The differences were not significant. There was no significant difference in dimensional changes between disinfected and non-desinfected

Telepraxis: An innovative educational method

"Telephone" has been used as an educational device for educational purposes in several university centers in the world. Nowadays, "Teleconference ", "Teleconsultation ", "Telemedicine" and "Computerized methods are common educational methods. Telephone in this study was used as an educational means to practice certain educational and professional subjects. In this study, telephone was used to practice important educational points by medical students. The method was called "Telepraxis" and the present paper introduces this innovative educational experience and reports the results of measuring the rate of students' satisfaction. In this study 4 different educational courses were presented to 508 students at pre-hospital, clerkship, and residency stages. The program was implemented for 15 sessions and at the end of each session, we inquired students' viewpoints about our suggested method by using a Lickert's type questionnaire that was designed with 24 characteristics of an effective educational method. We calculated the students' satisfaction index and compared the scores applying student T-Test. The participants' mean satisfaction index was 84.4%, which was significant/v higher than those of unsatisfied, [p < .001] The satisfication index for the students in clerkship stage was higher than that of the prehospital students or residents. Telepraxis in 4 courses of primary surgery, health cares, semiology, and CPR skills, was' approved by the learners on all the 24 traits of an effective teaching method