مجله دندانپزشکی دانشگاه علوم پزشکی تهران
سال سی و هفتم شماره 1 (پیاپی 109، بهار 1403)

Using fissure sealant is one of the most effective methods of preventing pit and fissure decay. Fluoride has been added to various materials as a known anti-caries agent. Fluorinated graphene (FG) has gained attention due to its unique properties. The specific structural characteristics of graphene fillers, besides having antibacterial properties by increasing the rate of fluoride release and charge and neutralizing the acidic pH of the environment, is a suitable option in many treatments. This study investigated the effect of addition of fluorinated graphene nanoparticles on the fluoride release in Fissurit®, a commercial fissure sealant.

In this in vitro study, fluorinated graphene oxide (FGO) with bright white color was prepared. After synthesis, 0, 1, 2 and 4 by weight percent were added to the fissure sealant (Fissurit®). Then, the release of fluoride in this material was measured and compared with the commercial fissure sealant containing fluoride (Fissurit®).

According to the obtained results, the amount of fluoride released from groups with different percentages of FGO had a direct relationship with the percentage of FGO addition. Also, at different times, there was a significant difference between the groups with FGO and the control group without FGO (P<0.001).

Addition of FGO to the fluorinated fissure sealant caused the release of fluoride and the possibility of recharging it. The power of releasing fluoride and its recharging in fissure sealant with FGO was higher than the fluorinated fissure sealant, but its fluoride was discharged at a faster rate.

One of the most important consequences of the rapid growth of urbanization has been the unequal distribution of urban service specially health care services and escalation of social inequality of citizens. Therefore, this study was aimed to analyze the spatial distribution of dental centers in Isfahan from the perspective of spatial equity.

This analytical cross-sectional study was conducted in 2023 in Isfahan city. The required data including the population of the fifteen districts of Isfahan city, the data of the geographic municipal areas and the dental centers of Isfahan city were put into Excell. The population data were gathered from the statistical yearbook of population and housing. The dentists’ data were gathered from the Medical Council. Addresses of the dental centers were fed into the Google earth and were found on the traffic map of Isfahan. Using the Arc GIS 10.8 software and based on the Geographic Information System concepts, the spatial justice was analyzed. Moran's autocorrelation index was used to determine the distribution pattern (cluster, scattered, random). Hot spot analysis and nearest neighbor distance (centers in this radius would have more access) were used. Access ratios were analyzed using the ratio of population to the distance of each parcel to the dental centers and then were categorized as privileged to, semi and unprivileged.

Z-score of Moran test was more than the expected score of 2.58 at 0.01 level of significant, indicating the cluster pattern of dental settings distribution in Isfahan. Moran's index (0.076) was much more than the expected equity coefficient (-0.000055), indicating again the cluster pattern of distribution which was not favorable in terms of spatial justice. The nearest neighbor distance analysis indicated that by moving from the center of the city to the outskirts of the city, access to dental centers decreased. Access analysis determined that privilege areas of the city were located mostly in central municipal areas and about 60% of these areas were limited to three municipal regions. Also, about 63% of the city area were categorized as unprivileged.

Distribution of dental centers in the city of Isfahan is not an equal distribution and the dental settings are mostly concentrated in the central areas of the city, not necessarily in high populated areas. There, this pattern necessitates the proper planning to establish dental settings in deprived and high-populated parts of the city.

Oral bacteria play an important role in oral diseases, due to their high adaptability to different environmental areas of the mouth. In this article, an attempt was made to describe the molecular mechanisms involved in the physiological relationships of oral and dental environment bacteria and their pathogenic significance with molecular approaches.

The present systematic review was written based on the advanced and standard search of keywords including Oral bacteria, Biofilm, and Dental diseases in PubMed, Springer, Scopus, Medline, Google Scholar, Science Direct, and Web of Science databases. For this purpose, an advanced and systematic search of articles published from 1993 to 2023 was conducted to compile the present article.

Bacteria in the oral cavity have nutritional adaptations that are important for living in pathogen-host relationships, including adapting to proteolytic living conditions, using the host's glycome as a nutritional interface. This includes the use of host-derived sialic acid and other glycosidases in oral bacteria. Some of these bacteria adhere to surfaces such as salivary, epithelial proteins, and glycans, which ultimately lead to biofilm formation. Bacteria living in the oral environment are constantly exposed to a wide range of stress-causing factors and oxidative stress in the biofilm.

Dental caries, pulp, periapical, and periodontitis diseases (including gingivitis) are among the most common bacterial diseases. Among them, tooth decay caused by the presence of Streptococcus mutans is the most common dental disease due to the production of acids from carbohydrate fermentation which is characterized by the demineralization of tooth structure.

 Anxiety is one of the most important issues in the dental environment for children. The aim of this study was to investigate the effect of music on the level of anxiety and cooperation of children during dental treatment.

 In this study 58 children aged 6 to 8 years were randomly divided into two groups: the intervention group (music played) and the control group (no music played). Children's anxiety was assessed using the Venham Picture Test and Frankel Behavior Rating Scale, and their heart rate was also measured.

 The results showed that in the intervention group, the level of anxiety based on the Venham Picture Test and Frankel Behavior Rating Scale was significantly lower. Additionally, the heart rate of children in this group was lower during the treatment (P<0.05).

 Based on the findings of this study, the use of music as a non-pharmacological method can be beneficial in reducing anxiety and improving the cooperation of children in the dental environment.

Temporomandibular disorders refer to a set of musculoskeletal problems that affect the temporomandibular joint, masticatory muscles, and surrounding anatomical structures. These disorders are associated with symptoms such as pain, click, asymmetry, or reduced maximum opening. The etiology of many temporomandibular disorders is complex, for this reason the initial treatments must be reversible and non-invasive. The use of occlusal splints is effective in reducing symptoms, and therefore, it is recommended in early and even long-term treatment of these disorders. These appliances play major role in developing conditions such as stabilizing joint position, creating favorable occlusal conditions that lead to normal muscle function, and protecting teeth and supporting structures against dental wear. The purpose of this article was to present a comprehensive review of occlusal splints in Persian language.

A search on Pubmed and Google scholar databases was done and the keywords "occlusal splints" and "temporomandibular disorders" were used. The inclusion criterion was articles published in English in the field of the types of occlusal splint between 1980 and 2020.

  In this review, the occlusal splints and their applications have been introduced.The success or failure of treatment with occlusal splints depends on various factors such as the correct selection of patients, the process of manufacturing, occlusal adjustment of splints, and the patients’ cooperation.

Nowadays, the requirement of any policy-making at the national and regional level is to know the level of knowledge of people about oral health and ways to prevent dental caries.  This study examined the habits, actions and economic level of elementary school students in Qazvin city in 2017-2018.  Also, the effects of peer group social network on behaviors related to oral health and obesity was investigated in order to find the way for interventions making it more effective in this social group.

In this descriptive-analytical study, 145 students participated. They were in the 3nd and 6th grades of elementary school in the academic year of 2017-2018. The questionnaire used in this study had 20 questions and 4 main sections. The main parts of this questionnaire included demographic characteristics, behavior and habits related to oral health, oral health knowledge of students and families, and socio-economic status. Data were collected through clinical examinations and through valid questionnaires and evaluated using SPSS and Excel software.

According to the results of Pearson's correlation analysis, a significant correlation was observed between the health knowledge scores of individuals and their friends between both groups of casual and close friends (P<0.01). The correlation between the knowledge of individuals and close friends was significantly stronger (P<0.01). Also, there was a significant relationship between socio-economic status and behaviors related to oral health (P<0.05). There was also a significant positive relationship between the number of times close friends brushing their teeth in a social network (P<0.001). This connection was not observed in the friends’ network.

This study determined that close friends can be effective in determining the oral hygiene behaviors of elementary school students.

To be successful in root canal therapy, the dentists must be aware of the possible variation in the root canal and should know not only the natural anatomy of the pulp, but also a variety of possible morphologies. Frst of all, the dentists should be familiar with the possible anatomy of the root canal and then with the extraction of organic tissue from pulp chamber and root canal, increasing the chances of treatment success. Therefore, in this study, we decided to investigate the internal anatomy of root canals in the maxillary permanent molar teeth in Khoy city.

In this in vitro study, 100 extracted human molars in Khoy city in West Azerbaijan province were collected. In all teeth, the access cavities were prepared, then they were decalcified and colored with India ink and evaluated by clearing technique. Data were collected based on Vertucci's classification which entered into SPSS23 software. The descriptive statistics in the form of numbers and percentages in tables and graphs were used to analyze the data.

The most common type observed in the mesiobuccal root of the first molars was type IV by 44%, in distobuccal root was type I by 92%, and in palatal root was type I by 94%. Also, in the mesiobuccal root of the second molars, the most common type was type I by 70%, in distobuccal root was type I by 94%, and in palatal root was type I by 96%.

The mesiobuccal root of the first molar had the most variation in the internal anatomy. Also, the most common type of Vertucci in the mesiobuccal root of first molar was type IV and in the other roots of the first and second molar teeth was type I.

Oral health literacy plays an important role in reducing oral health disparities. Evaluation of oral health literacy can be done at individual and population levels. This study was conducted with the aim of investigating oral health literacy among students of Shiraz University of Medical Sciences in 2023.

This study was descriptive, applied and cross-sectional. The research population included the students of different academic levels of Shiraz University of Medical Sciences, except the final semester students. The sample size was calculated based on the total number of students studying at different levels at Shiraz University of Medical Sciences in the second half of the academic year in 2023 using an appropriate statistical formula. Sampling was done in a stratified-random manner according to faculty, field, and level of education. The oral health literacy of the participants based on education level, age, and gender was measured by the oral health literacy adult questionnaire (OHL Adults Questionnaire: OHL-AQ). Data analysis was done using SPSS 27 software and descriptive statistics (mean, standard deviation, percentage), independent t-test, Kruskal-Wallis, and Tukey test.

The findings indicated that the average oral health literacy score of students was 14.75±1.37. Also, there was a statistically significant relationship between the average oral health literacy score of students and the parameters of education level, gender, and age of students (P-value < 0.05). This indictaed that the oral health literacy of students increased in the doctoral level and also with increasing age. In addition, the female students had higher oral health literacy.

Based on the results, the oral health literacy among Shiraz medical students was high. People with higher education level and age had higher level of oral and dental health literacy than people with lower education level and age. Oral and dental health literacy level was higher in girls than boys. It can be suggested that a 1) suitable platform be provided in order to improve the level of education of the society, leading to the improvement of the oral health literacy of the people; 2) regular dental examinations in order to increase the oral health literacy of the society is encouraged and promoted, especially in lower year students; and 3) research in effective training in the field of oral health literacy to increase the oral health literacy of people in the society.

Dentists faced the highest risk of infection during the COVID-19 pandemic. Educating competent students is the first task of the dental school to overcome the created problems and thus, it is necessary to recognize the created educational deficiencies. This study aimed to assess the students' perspectives from the Dental School at Tehran University of Medical Sciences during the academic year 2019-2020, concerning the competencies expected to be developed during the clinical phase of the general dentistry curriculum during the COVID-19 pandemic. The findings are intended to inform the formulation of educational strategies in the post-pandemic period to address identified gaps in training.

During the academic year 2019-2020, a cross-sectional descriptive study was conducted at the School of Dentistry, Tehran University of Medical Sciences, Iran. The study consisted of three phases: checklist design, psychometrics, and a survey of general dentistry students in their third to sixth year. The checklist design phase involved a team of four individuals, including educational officials from the faculty, academic staff members, and medical education experts. Experts confirmed the content validity of the checklist, while reliability was assessed using the Intraclass Correlation Coefficient (ICC), which indicated favorable validity and reliability. Subsequently, questionnaires formatted as Google Forms and a census approach were distributed to all students enrolled in the general dental course within the clinical section of the School of Dentistry at Tehran University of Medical Sciences. Ultimately, following the data collection process, statistical analysis was conducted utilizing descriptive statistics, including the mean and standard deviation, and the findings were communicated to the group managers.

The assessment of content validity was established at a minimum of 71%, based on the evaluations provided by five experts. Additionally, reliability was measured using an intra-cluster correlation coefficient (ICC) exceeding 0.79, signifying a strong level of both validity and reliability. 122 students (53%) in the clinical stage completed the forms related to the pre-clinical/clinical units passed during the Covid era. Despite having enough training, basics Removable Partial Prosthodontics, Surgery 1, and Restorative 3 courses needed more training. In addition, Basics Removable Partial Prosthodontics, Surgery 1, and Surgery 4 needed the most practical training to acquire the necessary competencies.

The findings of this research indicated that the dental students expressed a desire for increased practice across various levels of pre-clinical and clinical courses. This would suggest that the challenges associated with patient interactions during the COVID-19 pandemic may not be the sole contributing factor. Consequently, alongside the need for educational planning to address the requirements of enrolled students, it appears essential to conduct similar studies in the post-pandemic context. Furthermore, this approach may also prove beneficial in evaluating educational needs for ongoing professional development courses.

The bond strength of direct composite restoration to the caries affected dentin is a challenging issue. Preparation of dentin with an antibacterial agent is a method for creating durable bonded restorations. The aim of this study was to investigate the effect of curcumin photosensitizer on the bond strength of a universal adhesive to the caries-affected dentin (CAD).

In this experimental in vitro study, forty-four decayed human molar teeth were selected. After removing the surface enamel and dentin by a water-cooled saw, the decayed mid-coronal dentin was stained with a caries detection solution. The green and soft infected dentin was removed and CAD and hard and healthy surrounding dentin were left. Then, the remaining dentin surfaces were treated by 600 grit silicon carbide papers and polished. The specimens were divided into two groups (n=22): dentin pretreatment group by curcumin and control with no dentin pretreatment group by curcumin.  Each group was divided into two subgroups based on the method of application of All-Bond Universal adhesive (Bisco, USA) (etch and rinseand self-etching methods). After placing the Aelite All Purpose Body (Bisco, USA) composite, all  specimens  were placed in a universal testing machine for microshear bond strength (µSBS) test. The failure mode of the isolated surfaces was evaluated under a stereomicroscope. Two-way ANOVA analysis was used for statistical analysis.

Based on the obtained results, intervention with the adhesive application method and surface pretreatment with curcumin had no significant effect on the bond strength. Also, there was no significant difference in the bond strength of the curcumin group in both etch and rinse and self-etching methods (SE=56.3±27.11 MPa; ER=52.4±84.11 MPa) (P=0.847). In the curcumin-free group, there was no significant difference between the two different adhesive application methods (P=0.187).

The results obtained in the present study showed that the pretreatment of dentin affected by caries with light-sensitive curcumin and also use of a universal adhesive by either self-etching or self-etchinf methodshad no influence on the microshear bond strength of the composite restoration.

Idiopathic osteosclerosis is an asymptomatic local growth of cortical bone and is discovered incidentally on panoramic radiographs. The purpose of this study is to evaluate the frequency of idiopathic osteosclerosis and its radiographic features in panoramic images of patients referred to the Department of Maxillofacial Radiology, Faculty of Dentistry, Arak University of Medical Sciences (Iran) in 2022-2023.

In this cross-sectional study, 460 panoramic images from the radiology department of Arak Faculty of Dentistry were randomly selected and analyzed. The demographic information of patients, frequency of idiopathic osteosclerosis, location, and also its relationship with adjacent teeth in terms of proximity to lamina dura and periodontal ligament and radiographic features in terms of size and morphology were evaluated. The data were analyzed using the SPSS24 software.

Panoramic images of 460 patients (266 men and 194 women) with an average age of 38.12 (11.75) years were evaluated. The frequency of idiopathic osteosclerosis was 6.1% (28 images). 92.9% of the lesions were in the lower jaw and 46.4% of them were near the premolar teeth. In 39.3% of the cases, the lesion was adjacent to the periodontal ligament and laminadora of the tooth. In 3.6% of the cases, it was associated with a small displacement of the adjacent tooth, and 17.9% was associated with tooth root resorption. According to the results, there was no correlation between the incidence of this lesion with age and gender (P>0.05).

According to the findings of this study, the frequency of idiopathic osteosclerosis in the patients referred to Arak dental school was reported as 6.1%. Most of these lesions were observed in the back of the lower jaw and thus, it is important to be able to distinguish this lesion from the radiopaque lesions of the jaw which need treatment.

Today's working conditions in medical sciences, including dentistry, are changing rapidly. The explosion of scientific information on the one hand and the increase in consumer awareness on the other hand, along with the ever-increasing advances in artificial intelligence and access to the internet and the wide information network, has made health service providers face complex and different conditions. One of the ways to properly respond to the treatment needs of patients is to benefit from the best available evidence and clinical experience and to pay attention to the values and preferences of patients, which is manifested in the form of evidence-based practice. Dentists as members of the group of health service providers, must be familiar with evidence-based dental concepts and procedures and use them in their professional performance. This article discusses the steps of evidence-based dentistry to help empower dentists in the field of clinical decision-making based on the latest research benefiting from the best evidence and improving their clinical practice.

To find relevant articles in the field of evidence-based dentistry, PubMed scientific database and Google Scholar search engine were searched from 2000 to 2023 with keywords of Evidence-based dentistry, clinical practice, and decision making. Among the articles searched based on the inclusion and exclusion criteria, 15 articles in English whose main topic was evidence-based dentistry with an educational approach were selected and used to describe evidence-based dentistry and its components.

Due to the complexity of patients' issues and their increasing awareness, it is essential for dentists to possess specialized skills to meet patients' needs in accordance with their expectations and values, while also utilizing research findings.

Strong bond between the ceramic brackets and ceramic veneers has an important role in cosmetic treatment. The purpose of this study was to investigate the effect of aging on the shear bond strength (SBS) of ceramic brackets bonded to zirconia after surface preparation by Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser or sandblasting with alumina.

This experimental study was conducted on 24 zirconia blocks and these blocks were randomly divided into two groups for surface preparation and each was sub-divided into three time intervals. Surface preparation was done by sandblasting with alumina: in SG1 (Immediately after sandblasting), SG2 (2 weeks after sandblasting), and SG3 (3 months after sandblasting) groups. For the Nd: YAG laser (1/5W, 20Hz, 10s) with non-contact mode: in LG4 (Immediately after laser), LG5 (2 weeks after laser), and LG6 (3 months after laser) groups. The ceramic brackets were bonded to the zirconia blocks. The SBS and adhesive remnant index (ARI) were evaluated and compared among test groups. Dara were analyzed using Mann Whitney test.

There was no significant difference between the SBS of SG1 and LG4 (P=0.430), SG2 and LG5 (P=0.382) and SG3 and LG6 (P=0.326) groups. LG4 group showed the highest shear bond strength. After aging (2 weeks and 3 months), the laser groups showed higher SBS. There was no significant difference in the ARI between SG1 and LG4 (P=0.220), SG2 and LG5 (P=0.154), SG3 and LG6 (P=0.527) groups.

No significant difference was observed between the Nd: YAG laser and sandblasted groups in terms of SBS and ARI over time. Therefore, Nd: YAG laser could be used as a surface treamnet method in Zirconia crowns for bonding to ceramic brackets.

Multiple sclerosis (MS) is an autoimmune disease. Oral manifestations in these patients include paralysis or spasm of facial muscles, temporomandibular joint disorders (TMJ), trigeminal neuralgia, dysphagia, or dysarthria. The aim of the study was to investigate the characteristics of orofacial pain in patients with MS.

The current cross-sectional study was conducted on 250 patients with a definite diagnosis of MS referred to Iran MS Association and Iran MS Research Center. The patients were in the age group of 17 to 57 years and were selected completely randomly. Data were obtained based on two checklists and clinical examination. Finally, DC/TMD criterion was used to check TMD problems. Then the data was analyzed by SPSS version 26 software and by Fisher's Test.

The prevalence of MS disease was higher in women and the average age of patients was 37 years and the average duration of MS disease among patients was 8 years. The most common pain was related to shooting and shock-like pain with a frequency of 40.4% and the lowest quality was related to dull and diffuse pain with a frequency of 5.3%. In total, 24.5% of patients with buccal-oral pain had TMD, and in this case, the DC/TMD criterion was used.

  Temporomandibular disorders and shooting and shock-like pains are usually observed in a number of patients with MS.  As a result, dentists should be aware of the presence of these pains in the patient, the pain trigger, and the drugs used by the patients, in order to provide medical services and being aware of drug interactions.

Dental caries and periodontal disease are the most common chronic diseases. Health care workers specially “Behvarz” due to their wide range of duties, have the potential role in delivering education and prevention of dental caries. The purpose of the present study was to assess the perspective of “Behvarz” working in health care centers of Kordkooy city regarding oral health.

Focus group discussions was conducted with a convenient sample of “Behvarz” working in health centers of Kordkooy city.  Total number of 26 Behvarz with the mean work experience of 13 years took part in the study. After obtaining informed consent, group discussions performed in- person (2 groups of 7 and 2 groups of 6 participants) in health centers considering universal precautions. Two researchers coordinated the discussions. Five questions proposed on dental service utilization and oral health challenges and data collection continued until saturation obtained. The content of the discussion recorded and transcribed verbatim. For content analysis, two raters independently coded the content; sub-themes and themes were then extracted and consensus obtained.

More than half of the participants were 34 years of age and older. Regarding the challenges related to dental care in health centers, the main themes were; resource limitation, workload, lack of awareness of “Behvarz” role, limited access, economic barriers to prevention and care. Regarding the challenges to prevention, the main themes were; poor knowledge of patients, limited oral health related knowledge of “Behvarz”, and human resources. The main suggestions were emphasizing on the role of schools, mothers and patient education.

Our research showed that despite the important role of “Behvarz” in delivering oral health promotion at the population level, this role is neglected and needs further attention.

The quality of sleep plays a significant role in the academic performance of dental students, especially in the clinical years. Identifying and treating students at risk of sleep disorders can reduce or limit the drop in academic performance. The purpose of this study was to determine the relationship between the sleep quality and educational performance of Rafsanjan dental Student-Iran.

The present study was a descriptive-analytical cross-sectional study that was conducted among all dental students in Rafsanjan University of Medical Sciences - Iran. This study was presented to all dental students in Rafsanjan by online questionnaire method on Pressline website. The questionnaire included demographic information and student number along with the Pittsburgh Sleep Quality Standard Questionnaire. The Pittsburgh Questionnaire examines the quality of sleep in the range of 0 to 21. The link of the questionnaire was made available to the students through Telegram, and the GPA of the total students was obtained by using the student number from the Vice-Chancellor of University Education. The data were analyzed with SPSS26 software. First, the data were analyzed with Smironov's kermograph test. The results of this test showed that the data distribution is not normal (P<0.05). Due to the non-normality of the data distribution, non-parametric tests such as K-score, Mann-Whitney, Kruskal-Wallis and Spearman were used.

151 students participated in the questionnaire of which, 73 were men (48.3%) and 78 were women (51.7%). The mean and standard deviation of the age of the subjects studied was 22.11±2.3 years. The overall average sleep quality score of dental students was equal to 8.13, which according to the questionnaire, students experience poor sleep quality. 86.1% of students had poor sleep quality. Examining the correlation between the sleep quality and academic performance showed that there was no significant relationship between them. Sleep quality had no significant relationship with gender, marital status, place of residence, and entry year (P<0.05).

The results of the present study showed that majority of dental students in Rafsanjan had low sleep quality. Although, there was no relationship between the quality of sleep and academic performance, it seems necessary to pay attention to the sleep status of these students in order to improve their sleep quality, which is an important factor in improving their health by administrators and Rizan health program.

One side effect of orthodontic treatment is microcrack formation during debonding process. Since the type of ligation may affect the applied debonding force, this study was conducted to investigate the effect of ligation method on the enamel microcrack formation following debonding of orthodontic brackets.

The present study was an experimental in vitro study. 69 extracted human premolar teeth were divided into 3 groups with 23 teeth by a simple random method. A bracket was bonded on the buccal surface of the teeth, then the desired tooth was placed in a typodont where the rest of the teeth were mounted. Then, the arch wire was passively placed in the bracket slot. The samples were ligated by one of these three methods based on the study group: 1. Oring ligation 2. Tight ligation with a wire ligature for each tooth separately 3. Ligation of all arch teeth together, using a wire ligature. The buccal surfaces of the teeth were observed under a stereomicroscope and the length, location, and the number of microcracks were recorded before and after debonding process. In order to analyze the data, generalized estimating equation analysis was used.

In all three groups, a significant increase was observed in the average total length and number of enamel microcracks following the debonding process. (P<0.001 in all three groups), with no statistically significant difference between the three study groups. However, it was greater in group 2 than that of groups 3 and 1 respectively. In general, the number of new cracks was more in mid-buccal area followed by cervical and occlusal areas.

The debonding process caused an increase in the average total length as well as the number of enamel microcracks. Type of ligation might affect the enamel microcrack formation so that in tight ligation group we had the greatest increase in the enamel damage especially in mid-buccal area of the tooth. Tight ligation method can cause more enamel cracks than O-ring ligation and full arch ligation methods.

Emotional intelligence helps dental students better manage stress and establish effective communication with patients, while self-efficacy strengthens their confidence in performing clinical tasks and acquiring professional skills. The connection between these two factors leads to improved academic and professional performance. The aim of this study was to examine the relationship between the emotional intelligence, self-efficacy, and academic success among dental students.

This cross-sectional study included 55 dental students from Shahid Beheshti University of Medical Sciences - Iran, selected by convenient sampling. To measure academic self-efficacy beliefs, the Sherer questionnaire was used, which consisted of 17 questions with a theoretical score range of 17-85. To measure emotional intelligence, the Bar-On questionnaire was used, consisting of 90 questions with a theoretical score range of 90-450. Academic achievement was assessed using the students' grade point average (GPA). Additionally, gender, living at home or in a dormitory, and parental education levels were considered as background variables. The data were analyzed using descriptive statistics, t-tests, and Pearson correlation coefficient.

Among the 55 students who participated in this study, including 30 women and 25 men, the average emotional intelligence score was 84.85, the average self-efficacy score was 62.02, and the average GPA was 16.42. There was a significant difference in the emotional intelligence scores based on gender and living situation, with male students scoring higher than female students and dormitory residents scoring higher than those living at home (P=0.02). There was no significant difference in the self-efficacy scores and GPA between males and females. Students whose mothers had higher levels of education and those living at home had higher GPAs (P<0.03). No statistically significant relationship was found between the academic success and emotional intelligence or self-efficacy (P>0.05).

The findings suggest that while emotional intelligence and self-efficacy may not directly influence academic success, other factors like living environment and parental education can play a role. Understanding these dynamics can help educators focus on holistic student development, addressing not just academic skills but also personal and social factors that contribute to student performance and well-being.

The present investigation was conducted on the evaluation of the microstructure, phase transformation behavior, mechanical properties, and fatigue resistance of nickel-titanium rotary endodontic files. The main purpose of this investigation was to find the effect of microstructural parameters on the performance of these files.

Three rotary tools with brand names Denco, Edgeendo, and Eighteeth were studied. To evaluate the microstructure and transformation behavior of tools, metallography, X-ray diffraction, and differential scanning calorimetry methods were used. The bending test was used to check the behavior of superelasticity and memory and the microhardness test was used to evaluate the hardness of the samples. Also, cyclic fatigue behavior in a mold containing a simulated tooth canal was investigated and calculated by parametric statistical analysis. The fracture surface of the samples was also studied by scanning electron microscope.

Analyses revealed the existence of a high volume fraction of R phase in the microstructure of the Edgeendo file. Rotary files with higher volume fraction of martensitic phase showed higher shape memory effect and fatigue resistance. Denco and Edgeendo rotary files with better surface quality and high volume fraction of martensitic phases in the microstructure showed better fatigue resistance compared with the Eighteeth file. In all the results, the P-value was less than 0.05.

Multiphase microstructure containing austenite and martensite together with appropriate phase transformation and hardness of the alloy have key roles on functional properties of rotary files. This study provides dentists with a deeper understanding of the fatigue behavior and mechanical properties of these files, enabling them to make more informed decisions in choosing the appropriate instruments for endodontic treatment.

Ensuring the long-term stability of orthodontic treatments and preventing tooth relapse remains a significant challenge in orthodontics, often addressed through the extended use of retainers. Given the pivotal role of retainers' physical and mechanical properties in this regard, this study aimed to investigate the tensile strength, flexural strength, and deflection of three distinct types of fixed orthodontic retainers.

In this laboratory study, each group comprised 12 samples of twisted, flat, and coaxial retainer wires, each measuring 8 mm in length. These samples were affixed onto the polyethylene blocks using cyanoacrylate adhesive and subsequently subjected to compressive loads using a universal testing machine. The maximum bending strength and deflection rate were recorded from stress-strain diagrams. To evaluate the tensile strength, the identical samples underwent tensile loading. Statistical analysis was performed utilizing SPSS software, employing analysis of variance tests to compare data between groups.

Significant differences were observed in the bending strength (P=0.004), deflection (P<0.001), and tensile strength (P<0.001) among the investigated retainer wires. The flat retainer wire exhibited the highest bending strength, averaging 822.876±136.07 MPa, while the coaxial retainer wire showed the lowest, with an average of 673.65±73.35 MPa. Regarding deflection, the flat retainer wire displayed the highest average at 4.04±0.6 mm, surpassing the other two types of retainers. However, the tensile strength of the twisted retainer wires, averaging 699.7±83.46 MPa, exceeded that of both the flat and coaxial retainer wires.

The flat retainer wires demonstrated the highest bending and deflection strength, while the twisted retainer wires exhibited the highest tensile strength. Overall, the bending strength, deflection, and tensile strength of the 3-strand twisted and flat retainer wires outperformed those of the 5-strand coaxial retainer wires, increased flexural and tensile strengths imply a higher resistance of the wires to the forces induced by harder and more viscous foodstuffs.