مجله دانشکده دندانپزشکی مشهد
سال سی و نهم شماره 2 (پیاپی 93، تابستان 1394)

Several studies have shown that orofacial pains are common and affect about a quarter of the population at any time. This study was performed to survey orofacial pain among doctoral students (medical، dental، pharmacy) of Mashhad University of Medical Sciences in 2012-2013. This cross - sectional study was performed on 430 doctoral students from Mashhad University of Medical Sciences (Medicine، Dentistry and Pharmacy). A questionnaire based on the Von Korff & Macfarlane questionnaire was provided to the students. Data were analyzed، using Mann-Whitney، Kruskal-Wallis and Chi-Square tests. 24. 9 percent of the participants reported orofacial pains. The highest frequency of orofacial pains were in or around the eyes (10. 9%). Psychological factors were the cause of the pain in 30. 8% of the students. 75. 7percent of the students were seeking treatment for orofacial pain. Severity of disability among different educational levels، different age groups، different fields of study and between the sexes was not statistically different. Approximately a quarter of students were affected by orofacial Pain. The highest frequency of orofacial pain was in or around the eyes، which could be the result from studying. A significant number of students had professional seek for orofacial pain treating. This could indicate the effect of oral pain on people''s quality of life including job loss، difficulty in eating and concerns about oral health

One of the problems of all ceramic restorations is their probable fracture against the occlusal force. The aim of the present study was to compare the effect of two marginal designs (shoulder & chamfer) on the fracture resistance of all ceramic restorations, IPS e.max. On an extracted first maxillary premolar, a chamfer 50' margin (0.8 mm) was prepared. Twenty impressions were taken using polyvinyl siloxane. Then the chamfer was converted into shoulder 90' (1 mm). After impressing, epoxy resin dies were fabricated. Impressions of each epoxy resin die were taken and poured with die stone. Next, twenty Press crowns and twenty Zircad crowns were made on stone dies and cemented on resin dies. After that, samples underwent a fracture test with a universal testing machine. Data were analyzed by one-way ANOVA test. The mean value of fracture resistance was 1426N, for the chamfer Zircad samples 1361.3N, for the shoulder Zircad samples 1059.9N, for the chamfer Press samples and 1295.8N, for the shoulder Press samples. The One-way ANOVA test revealed no difference among the groups (P=0.095). After porcelain application, marginal design does not affect fracture resistance of single IPS e.max posterior crowns.

Given the increasing importance of saliva screening for various diseases and the seek for less risky and less costly ways to diagnose diseases; this study was designed to determine the relationship between oral dryness and osteoporosis. Twenty six postmenopausal women without osteoporosis and 27 postmenopausal women with osteoporosis were enrolled in this cross sectional study. The standard questionnaire of xerostomia was filled for all patients. Unstimulated saliva samples were collected by spitting method in the same place and same time. Data were analyzed by SPSS software version 18. Independed t test, chi square. The mean volume of saliva in patients with osteoporosis was significantly lower than patients without the osteoporosis (P=0.01), while dry mouth feeling was higher in this group (P<0.01). it seems that there is a positive relationship between osteoporosis and oral dryness feeling in postmenopausal women.

Using models and theories of health education plays an important role in promoting oral health. The aim of this study was to evaluate the impact of education based on the theory of planned behavior on caries prevention of permanent teeth in fifth grade students in the city of khaf. In this interventional semi-experimental، a sample of fifth grade students (N=61) from the city of Khaf (in winter of 2014) were selected by stratified cluster sampling. The subjects were divided into two groups of experimental and control groups. A questionnaire was given to each of them measuring demographics، knowledge، attitudes، subjective norms، perceived behavioral control، behavioral intention and behavior. The questionnaires were completed by students during the three periods: before، immediately after and one month after the intervention. Data were analysed using SPSS software version16. 5 using descriptive statistics and Pearson correlation test، Repeated Measures ANOVA and linear regression models (a=0. 05). The results showed significant differences in mean of attitude، subjective norm، perceived behavioral control، behavioral intention and behavior of brushing and flossing in the experimental group after the intervention had occurred (P<0. 001)، but no significant change was observed in the control group (P>0. 05). The theory of planned behavior could be used as an appropriate theoretical framework for the design and implementation of oral health interventions.

Developmental cysts of the jaws are relatively common bone destructive lesions in the human maxillofacial skeleton but their pathogenesis is still poorly understood. Among inflammatory cells, mast cells (MC) might be associated with their pathogenesis. On the other hand angiogenesis is important for the growth, expansion and distribution of lesions. The aim of the present study was to correlate angiogenesis with MCs density in odontogenic keratocysts and dentigerous cysts. In a descriptive-analytic cross-sectional study, 30 paraffin blocks of odontogenic keratocysts and dentigerous cysts were selected and stained immunohistochemically with CD34 and tryptase. T-test for independent samples and Fisher’s exact test were used for the statistical analysis of data. MVD was 2.07±0.53 and 7.96±1.23 in dentigerous cysts and odontogenic keratocysts respectively. Mean mast cells density was 3.93±2.35 and 12.12±4.37 in dentigerous cysts and odontogenic keratocysts. A Statistically significant difference was observed in MVD (P=0.05) and tryptase positive mast cells (P<0.001) between the odontogenic keratocysts and dentigerous cysts; a higher number of blood vessels and mast cells was detected in odontogenic keratocysts. The results suggest that CD34 and tryptase positive mast cells are strongly expressed in odontogenic keratocysts indicating that angiogenesis and mast cells may have a role in the aggressive behavior of odontogenic keratocysts. Lack of the correlation between mast cells number and angiogenesis in this study could be because of the developmental nature of these cysts.

Considering the importance of the dentist role in smoking cessation of smoker patients, the aim of this study was to develop a valid and reliable questionnaire for assessment of dentist counseling effect on knowledge, attitude and the smoker's stage of change in dental centers.

After literature review, an initial questionnaire containing three demographic questions, 16 phrases that showed a history of tobacco use, 5 phrases for specifying patient's stage in the change cycle, 7 phrases for knowledge assessment, and 27 phrases for attitudes assessment, was designed. To standardize and validate the questionnaire, qualitative assessment was done using an expert panel and quantitative assessment was done using content validity ratio (CVR) and content validity index (CVI). Reliability assessment was done by a test–retest method and use of Cronbach's alpha.

After validity assessment, questions with CVI and CVR less than the limit were corrected and modified. The validation process was repeated until the desired amount of CVR of 0.62 and the CVI greater than 0.79 were obtained. The reliability was confirmed with Cronbach's alpha value greater than 0.7.

This study provided a valid and reliable instrument for assessment of effect of the dentist counselling on knowledge, attitude and the smoker stage of change in dental centers.

Bleaching materials may influence the physical properties of resin composite restorations such as surface free energy. High surface free energy causes plaque accumulation and is an important factor for adhesion of bacteria to surfaces. The purpose of this study was to compare the surface free energy of Methacrylate-based Resin Composites with Silorane-based Resin Composites after bleaching. In this in vitro study, 48 samples of composite resin in the form of disks (8 mm diameter and 2 mm thickness) were prepared and divided into 4 groups (n=12). Samples of each group were in-office bleached with 35% hydrogen peroxide (three sessions of 45 minute, one week apart). The surface free energy (dyne cm-1) was measured with Angle Measuring System. Data were analyzed by one way ANOVA, Tukey and paired t-test at the significance level of 0.05. The mean and standard deviation of the surface free energy of P90, Z250, Z250 XT and Z350 XT composites after bleaching, were 50.09±6.22, 52.48±5.50, 61.38±4.62 and 54.59±2.41, respectively. Paired t-test analysis showed that there was no significant difference after bleaching in all composites except Z250 (P<0.05). Bleaching with 35% hydrogen peroxide caused a significant increase in the surface free energy of P90, Z250 XT and Z350 XT composites, but caused no significant difference in the composite Z250.

Odontogenic keratocyst (OKC) is a developmental odontogenic cyst that has high reccurrence rate and aggressive behavior. Dentigerous cyst is the most common developmental odontogenic cyst that may transfer to neoplasm. P53 and Murine double minute2 (MDM2) are over expressed in some odontogenic cysts and tumors. The aim of this study was to compare the expression of MDM2 and P53 in OKC and dentigerous cyst and their relation to proliferative activity of these cystsby immunohistochemistry. In this cross sectional study expression of MDM2 and P53 proteins were determined in 15 cases of OKCs and 15 cases of dentigerous cysts. Results were analysed with statistical tests Chi-square, t-student and the relative significance value of 0.05 considered. Expression of MDM2 and P53 had been observed in all the odontogenic keratocysts and dentigerous cysts. Expression of both markers were higher in OKC than dentigerous and expression were higher in suprabasal layers than basal layers (P=0.045). The severity of P53 and MDM2 were high in both OKC and dentigerous cysts, and there was a statistically significant difference between MDM2 and P53 in dentigerous cysts (P=0.032), but in OKC there was no significant difference (P=0.83). Expression of MDM2 and P53 had been higher in odontogenic keratocysts than denigerous cysts. Over expression of P53 and MDM2 may be associated with pathogenesis of OKC and dentigerous cyst and may contribute to biological behavior of these cysts.

The errors in the preparation such as change in canal curvature especially in curved canals almost always happen in the preparation step. Nickel- titanium rotary files that have been designed for canal preparation can reduce these problems. Preparation time is also important in root canal therapy and a rotary system which can prepare the canal in a lesser time, is more appropriate. The purpose of this study was to compare the curvature change of canal after preparation and instrumentation time in three rotary system; Reciproc, ProTaper and ProTaper Next. Forty-five resin blocks were used in this study. Each canal had a curvature of 25o to 35o and 15 mm length. Pre-instrumentation images of all blocks were taken with stereomicroscope and blocks were divided into three groups and each group was prepared with one of these systems: Reciproc, ProTaper and ProTaper Next. Post-insrtumentation images of all blocks were as well taken and the canal images were overlapped, and the curvature change of canal after preparation was measured. Active instrumentation time was also calculated during the preparation. Statistical analysis was performed using SPSS, version 16. Data were analyzed by ANOVA and Tukey tests (α=0.05). The results showed that the active instrumentation time was significantly less in the Reciproc group (P=0.034, P<0.001). Curvature change of canal after preparation was not significantly significant. According to the results, the three files in this study prepare the canal properly and change canal curvature negligibly and are safe instruments for preparation of curved canals. Reciproc files need lesser time for preparation and can prepare the canal faster.

Research on microbial contamination of individuals clothings has shown a variety of microorganisms. This contamination may cause infection and disease. The aim of this study was to determine the type and amount of aerobic bacterial contamination of dental student’s gown of Dental School of Shahid Beheshti University of Medical Sciences before and after treatment in 2013. During the study period 30 male dental students were selected by convenience sampling from restorative and periodontics departments. Sampling was performed from three part of gown before and after treatment using moistened sterile swab. The colony forming units were assessed and isolated bacteria were characterized by morphological and biochemical analyses. Statistical analaysis was performed using the Chi-square and Cochran Q test. P<0. 05 was considered as statistically significant. After finishing the treatment، in of 86. 7% of samples، the contamination was increased. The greatest contamination was related to Gram-positive bacteria. The Staphylococcus areus was the most common type of bacterium. Bacterial contamination of student’s gown is considerably increased after treatment of each patient. Therefore it is recommended that the surfaces near the patient are kept clean and sanitary measures are undertaken by the dental personnel during treatment in order to reduce microbial contamination.