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Background and Purpose: Although the evolution of industrial systems toward digital technologies decreased the exposure to high levels of noise, it has created some problems encountered with low level and provoking noise (low frequency noise). In the present work, the mental performance of students exposed to low frequency and reference noises at low and high levels (45 & 65 dB) were studied. Additionally, other factors such as annoyance, sensitivity to low frequency noise and hearing status of participants were considered.
Materials and Methods: After generating low frequency and reference noises required for the study, a pilot study was conducted. Then, 54 students participated in the main study after preliminary tests. Their mental performances were evaluated with standard psychological tests while they were exposed to low frequency and reference noises at 45 and 65 dBA.
Results: The results showed that noise annoyance and low frequency noise sensitivity do not have a significant correlation with age and sex. The results also revealed that, low frequency noise at 65 dB can decrease concentration (P=0.003) and increase response time (P=0.039) of performance in comparison with low frequency noise at 45 dB. On the other hand, reference noise at 65 dB can increase speed (P<0.001) of performance in comparison with reference noise at 45 dB.
Conclusion: Low frequency noise can reduce the mental performance and increase its response time.

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Background and purpose: Happiness is comprised of at least three components: emotional, social and cognitive. The emotional aspect results in positive expressions, the social aspect leads to expanded positive relationships with others and cognitive component creates a thinking which optimistically interprets daily events. This study evaluated the level of happiness and some influencing factors in medical students of Mazandaran University of Medical Sciences. Materials and methods: This descriptive cross-sectional study was done in all medical students (n= 356) who were consent to fill the questionnaire. The "Oxford Happiness Questionnaire" with a demographic questionnaire were completed by the students. The scores were analyzed by calculating mean scores of different groups and t-test and ANOVA using SPSS ver.17. Results: From the total of 356 medical students 208 handed the questionnaires. The mean score of happiness of medical students was 41.23. The mean score of happiness was significantly high (42.87) among students of medicine aged 18-22 years while it was lower (38.79) among those aged 22-31 years (P= 0.027). The mean score of happiness for medical students with physical disease was (35.06) which was lower than that of the healthy students (41.9) (P= 0.039). Findings from the study of five inventory factors showed different levels of self-esteem among male and female students of medicine (P= 0.005). Conclusion: The findings showed no relationship between sex, marital status, residential status and happiness among medical students but age and physical health influenced their level of happiness.

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Background and purpose: 2,4 dichlorophenol is one of the most important components of organochlorine. High resistance against degradation, creating odor and taste in water, high toxicity and being carcinogen have made this pollutant a great concern. Current study batch was done to investigate the adsorption of 2,4 dichlorophenol onto Magnetic Graphene Oxide Particles (MGO NPs).

Materials and methods: The adsorption behavior of 2,4-dichlorophenol was studied in a series of batch experiments as a function of pH (3-11), contact time (0-120 min), and pollutant concentration (10-125 mg/L) at three different adsorbent dosages (0.1-1 g/L). Finally, pseudo-first-order, pseudo-second-order kinetic, Langmuir and Freundlich isotherm models and adsorption thermodynamic were studied in optimized conditions.

Results: The results revealed in optimized conditions (pH=5, contact time=15 min, pollutant concentration= 10mg/l and adsorbent dose=0.75 g/l) maximum adsorption capacity and removal efficiency of 2,4-dichlorophenol were 84.74 mg/g and 100%, respectively. Langmuir isotherm (R²=0.9987) and pseudo-second-order (R²=0.9992) models were proved to be the best in describing the adsorption data. The thermodynamic parameters showed that the adsorption process was endothermic (ΔG= 57.7 to 119.15) and spontaneous (ΔG= -1.15 to -9.44).

Conclusion: MGO NPs have extended capabilities such as easy and rapid separation from sample and high potential in removing 2,4 dichlorophenol, so, it can be introduced as an appropriate adsorbent for removal of this pollutant from water and wastewater.

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Background and purpose: Recently, concerns regarding high concentrations of antibiotics in the environment have increased. Tetracycline is one of the most common antibiotics in human, agricultural, and veterinary treatments. This study aimed to evaluate the efficiency of Fenton oxidation process for tetracycline removal from synthetic wastewater.

Materials and methods:In this study, we assessed the effect of changes in initial antibiotic concentration (40-80 mg/l), molar ratio of [H₂O₂]/[Fe⁺²] (5-15), and contact time (5-30 minutes) on the efficiency of Fenton process. Tetracycline concentration was determined using high-performance liquid chromatography (HPLC). In addition, biodegradability rate was evaluated through chemical oxygen demand (COD)tests. Data analysis was performed in R software based on central composite design model.

Results:The optimal condition using Fenton process included initial concentration of 57 mg/l, molar ratio of [H₂O₂]/[Fe⁺²]= 11.27,and 30 min contact time which resulted in removal of 90.15% of tetracycline and 74.6% of COD.

Conclusion:Fenton treatment, which is a safe, cost-effective, and easy process could be used as an effective method to remove tetracycline from aqueous environments.

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Background and purpose: Identification of risk in hospital waste management have a major role in reducing the cost of surplus and preventing the spread of diseases. In this quantitative analysis, we aimed at determining waste components, evaluating hospital waste management, and prioritizing the risks in Sari Fatemeh Zahra Hospital.
Materials and methods: We performed a descriptive-cross-sectional study in 2015. Tchobanoglous method was used for quantitative-physical analysis of the waste. The individualized rapid assessment tool was applied to evaluate waste management. Preliminary Hazard Analysis and failure mode and effect analysis models were used to identify and prioritize the risks. 
Results: Total waste production, general waste, infectious wastes, and sharp objects were 1011.54, 600.45, 384.94, and 26.15 kg/day, respectively. Plastics, organic materials, and textiles constituted the highest amount of waste products. According to the individualized rapid assessment tool, the score obtained by the hospital was 82.15% indicating an excellent waste management. In preliminary hazard analysis, failure mode, and effect analysis models, 23 errors were observed, of which 9 had a priority number greater than 100.
Conclusion: The models studied showed that mixing the sharp waste material with other garbage, disposal of non-infectious and semi-household waste in infectious bins and vice versa are of high risk and need corrective measures.
 

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Background and purpose: Temporomandibular joint (TMJ) disorders are abnormalities that interfere with the shape or normal functioning of the joint, characterized by a group of clinical symptoms including pain, joint sounds, and limitation or deviation when opening the mouth. Considering the effect of skeletal relationships of the jaw on the shape, size, and morphologic variations of the condyle and its changes in TMJ, current study aimed at investigating radiographic changes in TMJ in patients with skeletal class II and III in Sari, Iran 2015-2018.
Materials and methods: In a retrospective cross-sectional study, 249 angle class II and 66 class III subjects were studied. After determining the skeletal relationship class using cephalometric radiographs, TMJ bone changes were investigated in panoramic images. Data analysis was done applying Chi square, T test, and logistic regression in SPSS V16.
Results: There was a significant difference in flattening distribution between class II and III subjects in patients aged 26-30 years old (P=0.036) and the prevalence of this disorder was higher in patients with skeletal class III. There were no significant differences between patients with skeletal class II and III in the prevalence of flattening, erosion, hypoplasia, and hyperplasia. TMJ disorders were significantly more frequent in females (P=0.035).
Conclusion In this study, the most and least frequent disorders were erosion after flattening and hyperplasia, respectively.
 
 

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     Background and purpose: Respiratory function of patients is a major part of orthodontic diagnosis and treatment planning. It is affected by the dimensions of the pharyngeal airway. In this study, these dimensions were compared in patients with different skeletal patterns.
Materials and methods: This cross-sectional descriptive-analytical study was performed studying the cephalograms of patients attending the Orthodontic Clinic affiliated with Mazandaran University of Medical Sciences 2016-17. After tracing, 144 cephalograms were divided into three groups: class I, II, and III (n= 48 per group) based on the ANB angle. The nasopharyngeal, oropharyngeal, and hypopharyngeal dimensions were measured. Data were analyzed using SPSS V24.
Results: The highest mean dimensions amongst nasopharyngeal, oropharyngeal, and hypopharyngeal spaces were found in class I (21.25mm), III (10.49mm), and III (15.89mm), respectively. There was no significant difference between class I and II in the nasopharyngeal space (P=0.108). There were significant differences in the mean dimensions of all three spaces studied between class I and III and class II and III (P <0.05).
Conclusion: Airway dimensions seem to vary among different classes of sagittal malocclusion. The dimensions of oropharyngeal and hypopharyngeal airways decrease with increase in ANB angle, but the dimensions of the nasopharyngeal airway are not associated with the changes in ANB angle and are higher in people with class I skeletal occlusion.

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Background and purpose: This study aimed to localize impacted maxillary canines and root resorption of neighboring incisors using cone beam computed tomography (CBCT) in 12-20-year-old patients referred to two private oral and maxillofacial radiology centers in Sari.
Materials and methods: In this descriptive-analytical study, 89 CBCT images were included. Of which, 31 images related to unilateral buccal impaction of the maxillary canine and 58 images related to unilateral palatal impaction of the maxillary canine were analyzed in order to measure the parameters of central and lateral resorption and the amount of resorption of these teeth. Data were analyzed in SPSS software (version 21) at a significance level of 0.05.
Results: Findings revealed no statistically significant relationship between gender and the side of indentation (buccal and palatal). Moreover, the highest position was related to the palatal site in both genders. Based on the chi-square test, there was no significant relationship between gender and latent canine position. Nonetheless, there was a significant relationship between age and latent position, as well as the occurrence of decayed lateral and the position of the impacted canine, which is the opposite of the lateral tooth in the central tooth.
Conclusion: This investigation revealed that the incidence of lateral tooth resorption was associated with the latent canine position, while the incidence of central tooth resorption did not demonstrate a significant correlation

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 Background and purpose: Condensing osteitis is the local reaction of bone to a pulp inflammatory stimulus with low intensity and long duration and is the most common radiopaque pathogen lesion in the jaw. The aim of the present study was to evaluate the frequency of condensing osteitis in apex of teeth with deep caries and restorations in panoramic radiographs.
Materials and methods: This cross-sectional study evaluated panoramic radiographs of 2039 patients attending Sari Dental School clinic for dental treatments during 2018-19. Demographic information, including age and sex were recorded. All panoramic radiographs were taken with Cranex D (soredex, Finland) panoramic device and Ortho CP-G Plus films. Lesions in the area of teeth with extensive restoration or deep caries (condensing osteitis) were examined in both jaws. Data were analyzed in SPSS V21 using Kolmogorov-Smirnov test, Fisher's exact test and Chi-square.
Results: According to findings, 364 panoramic radiographs had condensing osteitis. The frequency of radiopacity at the apex of teeth with condensing osteitis was significantly higher in women than men (P=0.042). But there was no significant association between condensing osteitis and border, shape, jaw type, tooth type, and age (P<0.05).
Conclusion: This study showed a relatively high prevalence of condensing osteitis in our patients in dental clinic at Mazandaran University of Medical Sciences. Current findings support the theory that condensing osteitis lesions may form a reaction associated with severely decayed, restored, or pulpitized teeth.

 

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Background and purpose: To achieve a successful root canal treatment, it is necessary to have a sealer with ideal characteristics that seal the permanent filling of the tooth canal. Over time, various sealers with different compositions have been introduced to increase the obturation quality of tooth root canals, and many studies are still ongoing to find the ideal sealer. This study aims to evaluate the obturation quality of Endoseal MTA sealer based on the void and spreader track in the root canal using intraoral digital radiography (PSP) and compare it with Adseal and MTA Fillapex.
Materials and methods: This laboratory study was conducted on 36 central maxillary single-canal permanent human teeth with the same shape and in the pre-clinic of the dental school of Mazandaran University of Medical Sciences. Root canal preparation was done with the Denco rotary system up to size F3 according to the manufacturer's instructions. During preparation, sodium hypochlorite 5.25% was used for washing, and finally  EDTA 17% and sodium chlorite 5.25%  were used to remove the smear layer. The teeth were dried with a paper cone. The samples were randomly divided into 3 groups and were filled with gutta-percha and sealers; MTA Fillapex, Endoseal MTA, and Adseal by lateral compaction method using Master Cone 35 and cone 20. After the sealers were set completely for 24 hours, PSP imaging was done with a parallel technique, buccolingually and mesiodistally, from the root canal of the teeth, and the presence of void and gaps in the form of spreader track in the three apical, middle and coronal regions, was evaluated with 3 independent observers. The data were evaluated with chi-square or Fisher's exact test, and items less than 0.05 were considered significant.
Results: In the current study, the obturation quality of MTA Fillapex, Endoseal MTA, and Adseal sealers was investigated on 36 teeth based on void and gap in the form of spreader track. These evaluations were done according to the direction and location of the sealers. In these evaluations, Adseal sealer had the lowest and MTA Fillapex had the most prevalence of spreader track prevalence, although these differences were not significant based on the chi-square test and there was no significant difference between the prevalence of Spreader track among the three sealers. The void was observed only in the Endoseal group in coronal (mean: 0.5) and apical (mean: 0.7) areas. The results of the Chi-square test showed that there was no significant relationship between the prevalence of void with coronal, middle, and apical sites in Endoseal (P<0.05).
Conclusion: No difference was observed between the three sealers in the voids and gaps in the root canal. Based on the results of this study, the obturation quality of the above three sealers isn't different from each other. Although the presence of more void in Endoseal MTA sealer was not significant, it can indicate that the handling of this material is difficult, on the other hand, according to the manufacturer's recommendation, this sealer is recommended for single cone method and is not suitable for use in lateral compression method.