seyyed alireza mackinejad

Face masks and respirators are used to filter inhaled air, which may contain airborne droplets and high particulate matter (PM) concentrations. The respirators act as a barrier to the inhaled and exhaled air, which may change the nasal airflow characteristics and air-conditioning function of the nose. This study aimed to evaluate the serum oxygen levels following the use of three-layer, five-layer and N95 masks after intervals of 1,2,3 hours in dental students of Azad University.

This cross-sectional analytical study was performed on 38 dental students of Islamic Azad University in 2020-2021. Initially, their arterial oxygen content was measured 20 minutes before the start of the study and at rest using a pulse oximeter. Then, for three days, the students put three-layer, five-layer and N95 masks on their faces, respectively, and after 1, 2 and 3 hours, their arterial oxygen level was measured by a pulse oximeter. SPSS software and one-way ANOVA, repeated measures ANOVA, Bonferroni and Tukey tests were used to analyze the data (p <0.05).

After one, two and three hours wearing the mask, the highest mean percentage of serum oxygen in the blood was present in the three-layer mask, the five-layer mask and the N95 mask, respectively. The mean serum oxygen saturation percentage one hour after wearing the mask was not significantly different between the groups without mask, three-layer, 5-layer and N95 masks (p <0.05). At two and three hours, the percentage of blood serum oxygen in the groups of three-layer, 5-layer and N95 masks was significantly lower than before the study (p <0.001). At two hours, the percentage of serum oxygen in the groups of three-layer masks was significantly higher than the five-layer masks (p = 0.027) and N95 (p = 0.014). At three hours, the percentage of serum oxygen in the blood in the three-layer mask groups was similar to the five-layer and N95 masks (p <0.05). In all three types of face masks, the evaluation time had an effect on the percentage of serum oxygen saturation in the blood (p <0.05). The mean percentage of serum oxygen in the blood before the study was not significantly different from one hour after wearing the mask (p <0.05). However, the mean percentage of serum oxygen in the blood at two hours (p <0.001) and three hours (p = 0.005) after wearing the mask was significantly lower than before the start of the study. The mean percentage of serum oxygen in the blood was not significantly different between one hour and two and three hours of wearing a mask (p <0.05).

After two or three hours of wearing face masks, the level of serum oxygen in the blood decreased. Respiratory consequences of decreased blood oxygen saturation can be harmful. Therefore, to prevent such consequences, it is recommended to take preventive measures.

  Amongst the various calcified structures in the human body, teeth have gained lot of popularity in estimating the sex of an individual as they are highly resistant to destruction and decomposition. The aim of this study was to determine the diagnostic analysis of mesiobuccal and distolingual dimensions of canine teeth in determining the gender in dentistry students in 2020.

This cross-sectional analytical study was performed on all dental students of the 5th semester (130 students) in the School of Dentistry of Islamic Azad University in 2019 and with all teeth except the third molar. Eligible for admission, an alginate mold was prepared from the upper and lower jaw arches and poured by dental yellow acetone plaster. Then, mesiodistal and buccolingual dimensions of permanent canine teeth were recorded using digital caliper. Data were analyzed by t-test.

In general, the mean age of students was 23.97±1.43 years (22-26 years). Out of 130 students, 72 (55.4%) were male and 58 (44.6%) were female. The mean mesiodistal and buccolingual dimensions of maxillary and mandibular canine teeth on both right and left sides in students were not significantly different (p <0.05).

The analysis of  dimensions of the permanent canine teeth has not any important role on determination gender.

One of the method for studying nonmetric traits is intraoral photography pictures .The aim of this research is , Comparison of the power of the intraoral camera to a  Extraoral camera to diagnose of morphologic non metric traits.

In this diagnostic  research we selected eligible samples ,among them at least 40 were without traits and 40 had the traits. At first with intra oral camera photo was  taken. Then, we took photo with a extraoral camera with a mouth opener and a mirror in the mouth with a 45 degree angle. At the end, the images were simultaneously judged on the monitor and studied. At the end of the study, the intraoral and extraoral camera.Findings were evaluated simultaneously on the monitor and analyzed statistically using fisher test.

Negative and positive diagnostic vaule of nonmetric traits in intraoral camera was 100% and extraoral traits was 100, and 68% respectively and the related difference was significant. P<0.0001)

Intraoral camera has more preference  than extraoral camera in diagnosis of nonmetric triats.