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Purpose: Loss of the bracket-tooth bond is one of the most common complaints of patients during orthodontic treatment. Various factors play a role in preventing the loss of such a strong bond between the bracket and tooth, one of which is the maintenance of proper isolation and prevention of contamination of tooth surface with blood during the surgical exposure of the impacted tooth. In case of bleeding during disimpaction treatment, the use of hemostatic agents might decrease the odds of tooth surface contamination with blood, resulting in a strong bond. This study aimed to evaluate the effect of different hemostatic agents on the bond between the bracket and tooth. Materials and Methods: 144 standard stainless steel dies were divided into two groups. Each of them includes 72 dies. These groups were divided into 12 equal subgroups as well. In both groups, die spacer was applied to dies in 0, 3, 4, 5, 6 and 7 layers (each layer=5µ). In the first group, crowns were cemented with Zinc Phosphate and in the second group, Polycarboxylate was used for cementing. After that, the strength required for separating the castings from the dies was measured. Results: The difference among 12 subgroups analyzed by one-way ANOVA regarding Polycar- boxylate cement did not reach statistical significance. (P=0.95). A similar result was obtained with zinc phosphate cement (P=0.616). Likewise, the two-way ANOVA was carried out between the zinc phosphate and polycarboxylate groups. There was a significant difference between the average of two groups (P<0.001). Conclusion: Range of cement layer thickness that used in this study didn’t statistically significantly affect the force required to remove cemented cast copings. Although the castings cemented with Zinc Phosphate needed higher force to be dislodged from dies.

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Objectives: This study aimed to evaluate the effect of an educational intervention on oral health-related knowledge, attitude, and practice of medical students. Materials and Methods: This study was performed on the fifth-year medical students attending an elective oral health course at the Faculty of Dentistry of Tehran University (intervention group) and 25 other students attending another elective course (control group) in 2018. A 2-week internship program including 6 sessions of a workshop program plus 2 days of school field and 2 days of attending dental departments was designed for the intervention group. Before and after the intervention, students completed a questionnaire and their simplified debris index was calculated. Statistical analysis was performed using SPSS version 24 by paired-sample t-test and general linear regression. Results: The mean age of the participants was 24.84±1.31 years in the intervention group and 23.64±1.28 years in the control group. There were 14 (56%) males in the intervention group and 16 (64%) males in the control group. At baseline, the mean knowledge, attitude and practice scores of the control and intervention groups were 26.28, 14.20 and 10.88, and 27.84, 15.80, and 9.36, respectively. After the intervention, the knowledge, attitude, debris index and willingness to adhere to oral health measures significantly improved (P<0.05). Conclusion: Oral health-related knowledge, attitude and practice of medical students were not desirable at baseline. The present study showed that even a short-term intervention in this field was effective to improve the oral health concepts in this group.