Journal of Dental Medicine

Background and Aims: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.

Background and Aims: 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.
Materials and Methods: 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.
Results: 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.
Conclusion: 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.

Background and Aims: 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.
Materials and Methods: 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.
Results: 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.
Conclusion: 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.

Background and Aims: 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.
Materials and Methods: 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.
Results: 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).
Conclusion: 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.

Background and Aims: The foundations of a successful root canal treatment are adequate adaptation of the gutta-percha to the canal wall and the establishment of an impermeable apical seal. Despite the common use of M3 and Neoniti rotary files by dentists, no study has been conducted to examine the compliance of gutta-percha in curved canals prepared with M3 and Neoniti files using CBCT. The present study was designed and compiled with the aim of investigating the adaptation of gutta-percha in curved canals prepared with M3 and Neoniti files by CBCT.
Materials and Methods: This randomized controlled laboratory study was conducted ex vivo on 30 permanent human first molar teeth. The teeth were randomly divided into two groups (the first group with M3 and the second group with neoniti), after finding and fixing the appropriate canal path with the examined rotary files. All groups were filled with Single Cone method using F2 gutta-percha and AH26 sealer. Then, the gutta adaptation was assessed using clinical criteria (visual and radiographic) and after the specimens were evaluated using CBCT. All the images obtained from CBCT were converted into the JPEG format and then entered into image J software. The gap between the canal walls and gutta was measured in each canal, and the obtained data were analyzed using the Mann–Whitney U test.
Results: The results showed that the average and standard deviation of gap in M3 files (0.181 ± 0.089) was higher than that of Neoniti file (0.173 ± 0.033). However, no significant difference in the gutta-percha adaptation in curved canals prepared between the M3 and Neoniti files  was observed (P>0.05).
Conclusion: Considering the acceptable adaptation of gutta-percha in canals prepared with M3 and Neoniti files, the use of these two files is recommended in curved canals.

Background and Aims: Educational planning is one of the main areas of education and training, which plays an essential role in the optimal training of human resources. The aim of this study was to compare the educational program (curriculum) of general dentistry in Iran with that of several prestigious dental schools in the Middle East countries.
Materials and Methods: This is a descriptive comparative study using the dental education curricula of six prominent countries in the Middle East in the field of dental sciences. Their selection was based on similarities and common cultural, economic and social characteristics. After collecting the selected curriculums, four steps including description, interpretation, juxtaposition and comparison were done. Tables were drawn based on goals such as the number of years of education, mission, general goals, and the role of graduates in the medical system of that country.
Results: The educational curriculum of the countries reviewed in the Middle East have many similarities in terms of the number of years of study in the field of dentistry, the general mission and goals, and the role of students in the medical system of that country. The main differences were in the number and type of teaching units in the curriculum of this countries. The method of teaching and the distribution of topics in the curricula of the countries differentiated them from each other. According to the results of this study, the curriculum of the countries of Iran, Saudi Arabia and the UAE were the most similar among the countries of the Middle East. The teaching method and distribution of topics in the curricula of countries distinguished them from each other.
Conclusion: Countries that are based on Russian language education have a shorter number of years of education and are similar to Russia. However, countries with an American educational base such as Saudi Arabia, the United Arab Emirates, and even Iran have a longer academic years and more general similarities in educational content.

Background and Aims: Third molar teeth extraction is one of the common treatments procedure in dentistry. The proximity of mandibular third molar teeth to the inferior alveolar nerve canal may make the surgery challenging and cause adverse complications. The purpose of this study was to determine the accuracy of diagnostic and evaluation of panoramic radiography findings in two classification methods (Rood-Shehab and Tanaka) according to CBCT in mandibular third molar extraction surgery.
Materials and Methods: This cross-sectional analytical study was conducted on 65 patients of a private radiology clinic in Qom who had simultaneous panoramic and CBCT radiography. Panoramic and CBCT radiographs were imported into Scanora and Ondemand softwares, respectively. The relation of the mandibular third molar with the inferior alveolar nerve was evaluated according to Tanaka's classification and Rood-Shehab radiographic signs and compared with CBCT radiographs. Finally, the obtained data were analyzed by chi-square test, ROC curve and SPSS software version 24. The significant level was considered at P<0.05.
Results: Out of 65 samples, 23.1% were men and 76.9% were women. The mean age of participants was 26.9±8.77. There was a significant relation between the Tanaka's classification of panoramic radiographs and proximity to the nerve in CBCT radiographs (P=0.011). This relationship was significant when the number of radiographic signs of the Rood-Shehab classification increased (P=0.044). Root darkening and diversion of mandibular nerve canal signs of Rood-Shehab classification showed more diagnostic accuracy in the nerve canal contact determination than that of other signs.
Conclusion: The probability of contact of third molar root with the inferior alveolar nerve canal increases with increasing in the number of Rood-Shehab radiographic signs. The root darkening sign was more accurate and followed by mandibular canal diversion sign. Tanaka’s classification can be used in differentiating cases without contact to the nerve canal.

Guided bone and tissue regeneration is a common technique used in the treatment of areas around teeth and dental implants. In this framework, barrier membranes are employed to create a suitable environment that promotes new bone growth while preventing the invasion of foreign cellular components into this specific setting. Attributes such as biocompatibility with living tissues, structural integrity, longevity, and user-friendliness constitute the principal criteria for selecting appropriate membranes for this particular application. Given the extensive diversity of membrane types concerning their sources, texture, architecture, and inherent properties, determining the most suitable variant depends on the clinical condition presented by the patient and the specific treatment modality, thereby emphasizing its considerable importance. In recent years, fibrous membranes have garnered particular attention due to their distinctive characteristics. These membranes, made of natural or synthetic fibers, typically exhibit high porosity, which facilitates the ingress of vascular structures and osteogenic cells. Owing to their porosity and flexibility, fibrous membranes are considered exceptionally suitable for the regeneration of maxillofacial and dental tissues, thereby contributing to increase bone volume, guide its growth, and at the same time prevent soft tissue encroachment into the restoration area, which ultimately has a favorable effect on treatment outcomes. On the other hand, due to the complexity and extent of oral infections, new nanotechnological approaches have been proposed in recent years to reconstruct infected sites in dentistry. These strategies, by targeting specific sites and having non-toxic properties, can help deliver antimicrobial molecules, regenerate tissue, and maintain oral health. In this context, nanofibrous membranes serve as multifunctional structures, both in the controlled release of antimicrobial agents and as scaffolds for the formation of nascent tissue. Overall, fibrous membranes, by mimicking the physiological conditions of the organism, create an ideal environment for the growth and healing of bone tissues, leading to improved effectiveness in dental procedures. This article is devoted in detail to a comprehensive review of polymeric and composite fibrous membranes with drug release potential.

Background and Aims: Sleep quality may be a predictive factor for temporomandibular disorders (TMD) compared to other risk factors. Patients with TMD may experience quality-of-life problems such as sleep disorders and orofacial pain. Timely diagnosis of TMD can halt its progression in the initial stages and reduce its severity. This study aimed to investigate the frequency and severity of temporomandibular joint disorders and their co-occurrence with sleep quality among dental students in Yazd in 2023.
Materials and Methods: This descriptive study was conducted among 211 students at the Yazd Dental School. The Fonseca and PSQI questionnaires were used to determine the severity of TMD and sleep quality, respectively. Clinical examination was conducted to assess the symptoms of TMD. Additionally, demographic information such as gender, marital status, and place of residence was recorded. The data were analyzed using chi-square and t-tests.
Results: The final analysis was performed on 211 individuals, comprising 118 males (56%) and 93 females (44%). Among all the participants, 204 individuals (83.88%) had at least one symptom of TMD.  The participants' most prevalent symptoms were jaw sounds, midline deviation, pain, and mouth opening limitation. There was no significant difference in the frequency of TMD symptoms, jaw sounds, jaw deviation, and limitation in opening, based on gender. Similarly, the prevalence and severity of TMD and their symptoms showed no significant association with residence or marital status (P>0.05). Although, a correlation was observed between the poor sleep quality and the severity of TMD, no association was found between the presence of TMD symptoms and poor sleep quality (P>0.05).
Conclusion: While, the frequency of TMD symptoms did not differ significantly between genders, the severity of TMD and jaw pain was significantly higher among female students. Individuals with poor sleep quality exhibited significantly higher severe degree of TMD.

Background and Aims: The status of oral diseases in children with visual impairments is a topic of concern for dental researchers. The aim of this study was to evaluate the rate of dental caries in these children according to the PUFA index.
Materials and Methods: To evaluate the rate of tooth decay, sixty 6-12 year old children with visual impairments were selected by convenience sampling in 2022 in Isfahan-Iran. The examination and pufa/PUFA index (exposed pulp, residual root mucosal ulcers, fistulas, and abscesses) were recorded.  Data were analyzed with Mann-Whitney tests (comparison of pufa/PUFA index according to gender, type of disorder and severity of disorder) and Spear-Man (examining the relationship between pufa/PUFA index and child age).

Results: The means of pufa/PUFA index in primary and permanent dental systشems were 0.89±0.68 and 0.44±0.2, respectively, of which the highest portion was related to the caries with pulp involvement. There was no significant relationship between the pufa and PUFA index according to gender, type of disorder, and severity of visual impairment (P<0.05). Also, only a significant and direct relationship was observed in pufa between the primary tooth system and age (P=0.042).

Conclusion: Untreated caries in children with visual impairment based on the PUFA index in primary and permanent dental systems had a relatively low prevalence. The highest  PUFA index portion was related to the tooth decay with pulpal involvement. Furthermore, untreated caries in primary teeth were increased by increasing the children’s age.

Background and Aims: Oral self-care among health care workers not only increases the oral health of individuals and their patients, but also improves the society's understanding of the prevention methods of oral disease. Therefore, this study aimed to investigate the oral self-care and compare it among dentistry, nursing, and midwifery students.
Materials and Methods: In this cross- sectional study in 2023, the HU-DBI questionnaire (Hiroshima University Dental Behavior Inventory) was applied to compare the oral self-care status among the first and final year students of dentistry, nursing, and midwifery. Volunteer students entered the study by a census sampling method. Data were analyzed using Spearman’s correlation coefficient, Kruskal-Wallis, and Mann-Whitney tests (P<0.05).
Results: In total, 348 students including 67% women participated in the study. No significant differences in the  mean score of oral self-care were found (P=0.676) among the first-year dental students (5.01±1.71), nursing students (4.81 ±1.81), and midwifery students (4.79±1.63). The mean scores of oral self-care among the final-year students in dentistry, nursing, and midwifery were 6.71±1.59, 5.13±1.62, and 5.17±1.61, respectively. Dental students had a significantly higher score of oral self-care (P<0.001).
Conclusion: Oral self-care among medical students in Azad University of Isfahan was average. Although, dental students revealed a higher level of self-care compared to the nursing and midwifery students, more training in this field is necessary.

Background and Aims: Musculoskeletal disorders are the most common and costly occupational injuries, and dentists are more prone to musculoskeletal problems than other medical professionals. This study aimed to investigate the effect of a course of corrective exercises on the alignment of the thoracic spine and balance in female dentists with increased kyphosis.
Materials and Methods: This research was a quasi-experimental study with a pre-test/post-test design, conducted in the field. Thirty female dentists from Amol and Babol cities (Iran) with increased kyphosis were selected using purposive sampling. The patients were randomly assigned into two groups: control (n=15) and intervention (n=15). In the pre-test, the thoracic curvature angle, static balance, and dynamic balance were assessed using a flexible ruler, the stork balance test, and the Y balance dynamic test, respectively. Then, the intervention group were assigned to perform the exercises for six weeks, while the control group only engaged in daily activities. After completing the exercises, the post-test was conducted. Paired t-tests and analysis of covariance were used to compare intra-group and inter-group differences.
Results: The statistical analysis  showed a significant difference between the two groups in the thoracic curvature angle (P=0.001), static balance (P=0.001), and dynamic balance (P=0.001). The intervention group demonstrated significant improvement in these parameters compared to the control group.

Conclusion: Based on the results of this study, it is recommended that corrective exercises under the supervision of a specialist be included in the weekly exercise program of female dentists with increased kyphosis.

 This article presents a challenging case of a 64-year-old man with episodic fever, urticarial rash, and arthralgia, prompting a detailed diagnostic process. Despite initial considerations of adult-onset Still's disease, the atypical symptoms led to further investigations, revealing a periapical abscess through a dental examination. The patient's symptoms significantly improved following dental intervention, challenging the initial diagnostic inclination towards a rheumatological disorder. This case underscores the importance of thorough physical examinations and interdisciplinary collaboration in reaching accurate diagnoses. The ultimate diagnosis of systemic presentation due to an occult dental abscess, highlights the need for a comprehensive approach to medical evaluations, considering various clinical aspects and avoiding diagnostics biases. This case study serves as a reminder of the evolving landscape of medical diagnostics and the continued significance of holistic patient assessments and physical examination as valuable practicing skills.

Background and Aims: To prevent dental caries, investigations have focused on finding new antibacterial and anti-biofilm agents without the drawbacks of the currently used synthetic agents. This study aimed to assess the effect of methanolic extract of Zingiber officinale (Z. officinale) on expression of virulence genes of Streptococcus mutans (S. mutans) using real-time polymerase chain reaction (PCR).
Materials and Methods: In this in vitro study, which was conducted in the year 1402, at the Microbiology Department of the Faculty of Medicine and the Faculty of Dentistry at Shahid Beheshti University of Medical Sciences, the methanolic extract of Z. officinale was obtained by the maceration technique. 10 clinical isolates of S. mutans were obtained from the patients with dental infection. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract against S. mutans were determined by the microtiter plate technique. The effect of extract on the expression of relA, comDE, brpA, gtfC, and spaP virulence genes by the clinical isolates was evaluated by the real-time polymerase chain reaction (PCR) technique. Data were analyzed by the Wilcoxon and Mann-Whitney tests (alpha=0.05).
Results: The mean MIC and MBC of the methanolic extract of Z. officinale against S. mutans were 32±11.8 and 64±26.12 mg/mL, respectively. The extract caused down-regulation of relA, comDE, brpA, and gtfC by 50%, 40%, 70%, and 70%, respectively. It also caused 4 times reduction in expression of spaP gene.
Conclusion: The methanolic extract of Z. officinale caused significant down-regulation of gtfC, brpA, relA, comDE, and spaP genes, indicating its optimal efficacy to control the virulence of S. mutans.

Background and Aims: Achieving reliable tools for accurate shade matching of ceramic samples is of great importance in restorative and aesthetic dentistry. This study aimed to evaluate the accuracy of the Trios5 intraoral scanner in determining the shade of ceramic samples using the Vita Classical Shade Guide (VC).
Materials and Methods: This in-vitro study involved scanning each ceramic sample 15 times by two independent observers using the Trios5 intraoral scanner. The detected shade of each sample was compared with the reference shades of the Vita Classical Shade Guide (VC) and the compatibility of the scanner’s results with the reference shades was assessed. The data were analyzed using SPSS24 software and Pearson correlation and paired t-tests and kappa coefficient at a significance level of 0.05.
Results: The highest accuracy of shade detection in both observers was found for shades A2, A3, A3.5, A4, B1, and C4, each with 100% accuracy. The lowest accuracy for both observers was noted for shade A1, with 0% accuracy. The mean overall accuracy for the first and second observers was 64.99% and 63.75%, respectively, with a total overall accuracy of 64.37%. A statistically significant interobserver agreement was observed (P≤0.005).for all shades except B2 (P=0.299).
Conclusion: The Trios5 intraoral scanner can be considered a useful adjunct tool for ceramic shade determination. However, for clinical applications, it is recommended to use it in conjunction with reference tools and complementary methods such as spectrophotometry or visual assessment by experienced clinicians.

Background and Aims: Despite documentation on the antiviral effects of cetylpyridinium chloride (CPC) and nano-silver colloid (Ag) on herpes simplex virus type 1, the synergistic effect of these two materials at different concentrations is unknown. This study aimed to evaluate the antiviral effect of various concentration combinations of cetylpyridinium chloride and nano-silver colloid on herpes simplex virus type 1.
Materials and Methods: This laboratory study conducted at the molecular virology department of Iran Pasteur Institute in the year 1400. After testing the cytotoxicity of different concentrations of CPC and Ag, the disinfecting effect of safe concentrations of each substance individually and also in the form of three compounds, was examined on the cells infected with herpes simplex virus type 1. The study groups included groups 1 to 6 with 0.01 µg/ml to 1000 µg/ml of Ag, groups 7 to 12 with 0.1 µg/ml to 10000 µg/ml of CPC, and combination groups of Ag 10 µg/ml + CPC 10 µg/ml (G13), Ag 10 µg/ml + CPC 1 µg/ml (G14), and Ag 1 µg/ml + CPC 10 µg/ml (G15). Data were analyzed using One-Way ANOVA and Games-Howell and Tukey HSD pair comparison tests at a significance level of 0.05.
Results: Based on the MTT test and the cell viability exposed to herpes simplex virus type 1, the highest number of living cells belonged to the 10 µg/ml Ag group, followed by 10 µg/ml CPC, 10 µg/ml Ag + 10 µg/ml CPC, 1 µg/ml Ag + 10 µg/ml CPC, and 10 µg/ml Ag + 1 µg/ml CPC groups. In terms of antiviral effect, there was a significant difference between group 1 and groups 3, 4, 5, 6, and 10 (P<0.001), between groups 2 and 3 (P=0.40), between groups 2 and 4 (P=0.041), between group 2 and groups 5 and 6 (P=0.035), between group 7 and groups 10, 11, and 12 (P<0.001), between group 8 and groups 10, 11, and 12 (P<0.001), and between group 9 and groups 10, 11, and 12 (P<0.001). Among combination groups, the most antiviral effect and the least cell toxicity was found in the 10 µg/ml Ag + 10 µg/ml CPC group, while the least antiviral effect was observed in the Ag 10 µg/ml + CPC 1 µg/ml group.
Conclusion: The highest cell viability rate belonged to the 10 µg/ml Ag group, followed by the 10 µg/ml CPC group, and their combination resulted in a reduction of its effect in this area. The antiviral effect of these materials individually was greater than in their combined state. Additionally , the most antiviral effect and the least cell toxicity was found in the 10 µg/ml Ag + 10 µg/ml CPC group among the combination groups.

Background and Aims: Repairing existing composite restorations, rather than replacing them entirely, is regarded as a conservative and tissue-preserving approach in restorative dentistry. However, achieving a durable bond between the aged and newly applied composite resin remains a significant clinical challenge. This study aimed to compare the shear bond strength of repaired composite restorations using three different adhesive systems.
Materials and Methods: In this in vitro study, which conducted at the Faculty of Dentistry, Urmia University of Medical Sciences, 60 disk-shaped composite specimens were fabricated with standard dimensions. After undergoing artificial aging (storage in distilled water for 6 months), their surfaces were roughened mechanically using a diamond bur. The specimens were randomly divided into three groups (n=20) and repaired using fifth-generation (Adper Single Bond), seventh-generation (OptiBond All-In-One), and universal (Single Bond Universal) adhesives, followed by the application of new composite. All  specimens were subjected to thermocycling, and the shear bond strength was measured using a universal testing machine. Fracture patterns of the samples were also examined using a stereomicroscope to determine the modes of failure. Data were analyzed using one-way ANOVA and Chi-square tests in SPSS at a significance level of 0.05.
Results: The mean shear bond strengths were 15.22 ± 4.47 MPa for Adper Single Bond, 14.05 ± 4.66 MPa for OptiBond All-In-One, and 13.44 ± 4.68 MPa for Single Bond Universal. No statistically significant differences were found among the groups (P=0.468). Fracture pattern distribution was also not significantly different (P=0.453), with predominantly cohesive or mixed failures observed across all groups. No adhesive failures were observed.
Conclusion: Under standardized surface preparation, none of the tested adhesive systems demonstrated a statistically significant advantage in the shear bond strength between the aged and new composite. Therefore, the choice of adhesive in composite repair procedures can be guided by practical considerations such as product availability, ease of application, and dentist preference.

Background and Aims: Musculoskeletal disorders (MSDs) are among the most common occupational health problems faced by dentists. Given their impact on dentists’ health and performance, the present study aimed to investigate the prevalence of MSDs among general and specialist dentists practicing in Babol, Iran.
Materials and Methods: In this cross-sectional study, the standardized Nordic questionnaire, consisting of general and specific sections, was distributed in person among dentists practicing in Babol, based on data obtained from the local Medical Council. Distribution was carried out after a telephone invitation and confirmation of willingness to participate. The questionnaire included items regarding pain and discomfort in different body regions such as the neck, shoulders, and lower back. The frequency of participants with MSDs was assessed based on gender, right/left handedness, specialty, playing sports, and participating in a specific sport. The mean age, weight, height, body mass index, weekly working hours, and work experience of dentists with and without MSDs were also compared. Data were analyzed using SPSS software version 22, employing independent t-tests, Chi-square tests, and Fisher’s exact test, with a significance level set at 0.05.
Results: Of the 182 dentists approached, 17 declined participation and 5 met the exclusion criteria. A total of 160 dentists (mean work experience: 15.65 ±9.26 years) were included in the study; of these, 100 (62.5%) were male, 95 (59.4%) were general practitioners, and 65 (40.6%) were specialists. The overall prevalence of MSDs in this population was reported to be 90%. The most commonly affected region was the neck (76.4%), while the least affected was the ankle (3%). A statistically significant association was found between engaging in a specific type of regular physical activity and a reduced incidence of MSDs (P<0.001). No significant associations were observed with other variables such as gender, handedness, specialty, or field of specialization (P>0.05). Furthermore, no significant differences were found in the mean height, weight, body mass index, weekly working hours, or years of experience between dentists with and without MSDs (P>0.05).
Conclusion: Musculoskeletal disorders are highly prevalent among dentists in Babol. Given this high prevalence, the development and implementation of educational programs on ergonomics, along with recommendations for targeted physical activity appear to be essential.