مجله دانشکده دندانپزشکی مشهد
سال چهل و نهم شماره 1 (پیاپی 132، بهار 1404)

Monolithic zirconia crowns are used for restoring aesthetics and function in the dentition. However, the stress distribution pattern in these crowns remains relatively understudied. This study aimed to investigate the effect of cement thickness and type in the margin area and 1 mm above the finish line on the stress distribution pattern in monolithic zirconia crowns.

Sixteen finite element models were made using Mimics Medical and SolidWorks software. The models simulated a human premolar tooth that was restored with a monolithic zirconia crown. Models differed according to the utilized cement (zinc phosphate, Panavia, Glass ionomer, and RelyX) and the cement thickness at the marginal area. Each model was subjected to a force of 100 N applied at a 45º angle. Finite element analysis was performed using Abaqus software, and the stress distribution and concentration areas were determined.

Finite element analysis results showed that the highest stress of cement occurred when cement was present in the margin area, while the lowest stress was observed when no cement was used in this area. Zinc phosphate cement exhibited the highest tensile stress, whereas RelyX showed the least. As the elastic modulus of the cement decreased, the stress in the crown increased.

In monolithic zirconia crowns, when no cement is present at the margin, the lowest stress is concentrated in the cement, and the highest stress is concentrated in the crown. RelyX cement accumulates the least stress within itself, leading to higher stress concentration in the crown, whereas zinc phosphate cement absorbs the highest stress and results in the least stress concentration in the crown.

The purpose of this study was to compare the effect of diode laser and resin infiltration on the shear bond strength (SBS) of orthodontic brackets bonded to demineralized enamel surfaces.

Thirty six sound extracted maxillary premolars were collected for this in-vitro study. Samples were demineralized at 37ºC over the course of 48 hours. Specimens were randomly divided into three equal groups (n=12), namely: Group 1 (control group): no surface treatment was applied. Group 2: resin infiltration (DMG, Hamburg, Germany) was preformed prior to bonding. Group 3: enamel surfaces were irradiated with diode laser (970 nm,  2 W) for 15 seconds with continuous scanning. Orthodontic brackets were bonded to the prepared surfaces of all specimens. The SBS values were recorded using a Universal Testing machine. ANOVA was used to compare SBS values between different study groups followed by Tukey’s post hoc test for pairwise comparison. P-value <0.05 was considered statistically significant.

Group 2 demonstrated the highest mean SBS values (6.62 ± 0.75 MPa), followed by group 1 (6.24 ± 0.76 MPa) and group 3 (4.80 ± 0.68 MPa), in descending order. According to ANOVA, there was a statistically significant difference between the average SBS values among the three study groups (P=0.001).  Pairwise comparison revealed that the mean SBS value recorded for the laser-treated group, was significantly lower than that of the resin infiltration  and control groups (P=0.001 for both). However, the difference between the SBS of the resin infiltration group and the control group was not statistically significant (P=0.423).

Surface pretreatment with diode laser irradiation resulted in low SBS values, indicating a weak bond strength between the orthodontic brackets and demineralized enamel surfaces. These findings suggest that diode laser surface treatment is not effective for bonding orthodontic brackets to teeth with white spot lesions.

Body dysmorphic disorder is a psychological condition in which an individual persistently focuses on minor or imperceptible flaws in their appearance. This disorder has a high prevalence among orthodontic patients and can affect the patient's perceived need for treatment and treatment outcomes. Therefore, the aim of this study was to evaluate the relationship between body dysmorphic disorder and the aesthetic component of the index of orthodontic treatment need (IOTN-AC) and IOTN-AC determined by examiner (IOTN-ACE).

This descriptive study was conducted on 228 eligible orthodontic patients over the age of 12. Demographic information of the patients was recorded. Patients completed the Yale-Brown Obsessive-Compulsive Scale modified for body dysmorphic disorder (BDD-YBOCS) questionnaire. The aesthetic component of the index of orthodontic treatment need was determined through a visual questionnaire completed by both the patient and the orthodontist. Data were analyzed using the Chi-square test and Fisher’s exact test, with p<0.05 considered statistically significant.

In this study 19.7% of the patients were identified as having body dysmorphic disorder. The prevalence of body dysmorphic disorder in patients with a moderate treatment need based on IOTN-ACE (29.1%) was significantly higher than in the no treatment need group (15.5%) and the definite treatment need group (12.1%) (p=0.032). Additionally, no significant relationship was found between body dysmorphic disorder and IOTN-AC, as well as gender, marital status, and age group (p>0.05).

The results of the study indicate that moderate treatment needs, as perceived by the orthodontist, can lead to greater psychological anxiety and body dysmorphic disorder in patients. Furthermore, the need assessed by the orthodontist does not necessarily align with the need perceived by the patient.

Scientometric studies in various dental specialties are relatively scarce. This study aimed to conduct a bibliometric analysis of the research scholarly output of Iran regarding orthodontic-related research, based on data retrieved from the Scopus citation database using SciVal.
The SciVal platform was utilized to analyze all documents relevant to orthodontics published in Iran from January 2014 to December 2023. Key indicators examined included FWCI (Field-Weighted Citation Impact), the number of published scientific documents, the extent of international collaboration, the main topics of the articles, and the journals in which these articles were published.
The findings revealed that the number of Iran's scientific papers published in the filed of orthodontics increased by 94.4% from 2014 to 2023, accounting for 3.3% of all scholarly orthodontic articles globally. A remarkable 25.5-fold increase in the number of Q1 articles from Iran was observed in 2023 compared to 2014. However, the FWCI declined from 0.93 to 0.61. Among the articles published over the past decade, the topics of adhesives and bonding had the highest number of publications. Additionally, the number of internationally co-authored documents in 2023 showed a 2.5-fold increase compared to 2014.
Iran's scientific output in orthodontics has shown an increasing trend, indicating the potential for further growth. With meticulous planning and strategic measures, this field could be distinguished as a leading area of scientific production in the country.

This review article aimed to evaluate and compare the color change outcomes of two tooth whitening methods, namely, home bleaching and laser bleaching, and to also assess their efficacy and safety.

A comprehensive search was conducted across reputable scientific databases including, PubMed, Scopus, ISI and Google Scholar using keywords related to "teeth bleaching", "home bleaching", "laser bleaching" and "tooth color change". The inclusion criteria consisted of in vivo and in vitro studies, published from January 2013- July 2024 in English. The full texts of the eligible articles were retrieved and evaluated. Data extraction was completed and data was analyzed according to the type of employed bleaching method, year of publication, and study outcomes.

From 55 identified articles, 9 were qualified for full review. The findings highlighted that both home bleaching and laser bleaching are effective in improving tooth color. Home bleaching using 20% carbamide peroxide resulted in more significant color changes and provided more stable and safer outcomes compared to laser bleaching. Although laser bleaching using diode lasers and Er, Cr:YSGG lasers also showed positive results, the overall degree of color change was generally less than that of home bleaching. Additionally, studies indicated that home bleaching is associated with less damage to tooth enamel.

Home bleaching with 20% carbamide peroxide is identified as the best option for teeth whitening, as it offers more stable results and greater color change. However, further studies are needed to improve laser bleaching techniques and reduce their potential adverse effects. Therefore, additional research with larger sample sizes and real clinical conditions is recommended to better evaluate the efficacy and durability of bleaching methods, assess their long-term impact on tooth and enamel health, and develop optimized laser bleaching techniques aimed at minimizing damage and enhancing efficiency.

Mothers are mainly responsible for their child’s oral and dental health during childhood and must acquire adequate oral health literacy especially regarding the primary dentition. Therefore, the present study investigated mothers' oral health literacy level and its relationship with children's oral health status.

This descriptive cross-sectional study, included 195 children with 3-6 years of age and their mothers, who referred to the Pediatric Dentistry Department of Yazd Dental Faculty in 2024. Children were divided into four age groups; 3, 4, 5 and 6 year olds. Mothers ' oral health literacy was assessed using the OHL-AQ (Oral Health Literacy-Adult Questionnaire). Each mother obtained an oral health literacy score, with 100 being the highest score possible. Children’s dmft was recorded through clinical examination. Data were analyzed using SPSS25 software and Mann-Whitney, Kruskal-Wallis, Spearman's correlation coefficient, and multiple linear regression tests. The significance level was considered to be 0.05.

Mother’s average oral health literacy score was 60.11±51.78. The average dmft index of children was 4.06±1.35. The average number of decayed  teeth (d) was 2.23±1.40, filled (f) was 1.05±0.86, and missing (m) was 0.77±0.86. In all four age groups, there was a positive relationship between the mothers’ oral health literacy score with dmft index, the number of decayed teeth, and the number of missing teeth, and there was a negative and significant relationship with the number of filled teeth in their child (r= -0.807, P<0.0001). Oral health literacy and children's age were predictors of children's dmft index (P<0.001).

In mothers with higher oral health literacy, the average dmft index, the number of decayed and missing teeth in children was lower, and the number of filled teeth was greater.

Intraoral scanning is used in digital impression taking. Scan bodies are used for three-dimensional implant scanning. These parts help to accurately transfer the position, location and angle of the implants to the laboratory technician. Each scan body consists of three parts: the base, body and scannable surface. The scannable surface is available in different shapes, sizes and materials. This study aimed to evaluate the various factors affecting the accuracy of scan bodies and to also determine the prosthetic techniques that would enhance the accuracy of digital impressions taken from edentulous jaws.

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020. A comprehensive search was conducted across databases such as PubMed, Scopus and Google Scholar using terms related to “CAD/CAM”, “implant impression”, “edentulous”, “dental implants” and “oral rehabilitation”.  Studies that were published from January 2015-Feburary 2024, in English language, were retrieved.

A total of 295 studies were initially identified and 49 articles were screened by title and abstract. After eliminating studies that were irrelevant to our PICO model, the full text of 23 article were reviewed. Scan bodies are categorized as either clinical or laboratory. The following factors were identified as influential factors affecting the accuracy of scan bodies: height, diameter, geometric shape, placement angle, torque, and material.

This study showed that some prosthetic methods can be employed to increase the accuracy of the final digital impression taken in edentulous jaws. These methods include using the continuous bar strategy, modified scan bodies or reverse scan bodies.

The aim of the present study was to evaluate the changes in body mass index (BMI) and food intake in patients undergoing orthognathic surgery during their hospitalization period and until the end of intermaxillary fixation (IMF).

This study included a total of 36 patients, scheduled for bimaxillary or monomaxillary orthognathic surgery in Emam Reza Hospital, Tabriz, Iran. Participants were healthy adults within the age range of 18-50 years. Demographic information was recorded in a corresponding questionnaire. Patients’ height was measured at the day of hospital admission. The patient’s weight was measured and recorded at three time points: the day of admission (T1), upon discharge form the hospital (T2) and after IMF was removed (T3). BMI was calculated (kg/m2) for each patient at all three mentioned time points. Information on food intake was collected using a 24-hour recall questionnaire on T1, T2 and T3. Nutritionist IV software was used to analyze the dietary intake of carbohydrates, protein and fats as well as the energy intake. Changes in patients’ BMI values, amount of macronutrient and energy intake were evaluated using repeated measures ANOVA. P-value <0.05 was considered statistically significant.

Participants comprised of 18 (50%) male and 18 (50%) female patients with an average age of 26.7±8 years. Patients’ BMI values exhibited a decreasing trend from T1 to T3, which was proven to be statistically significant (P<0.001). The average amount of energy, protein, fat and carbohydrate intake significantly decreased during the T1-T3 interval, i.e. from the preoperative state until after IMF was removed (P<0.05).

According to the obtained results, orthognathic surgery caused a significant reduction in the BMI of the patients, which was probably due to a decrease in energy, protein and fat intake during the IMF period.

Considering the importance of painless injection is dentistry, the aim of the present study was to compare the level of experienced pain and stress associated with two different injection methods used for buccal infiltration, namely: the two-stage injection and the computer-controlled injection techniques.

This cross-over clinical trial study was conducted in a split-mouth design and included a total of 28 healthy children with 5-7 years of age who required pulpotomy treatment on the both primary maxillary first molars. Two-stage and computer-controlled injection anaesthesia were used to perform local buccal infiltration and anesthetize the pulp of the teeth. The level of stress was assessed through pulse rate. Pain was measured using the objective Sound Eye Motor (SEM) Pain scale and also subjectively using  Faces criterion. Pulse rate and Faces criterion were measured at three different time points: one minute before injection (T1), during injection (T2) and at the time of pulp exposure (T3). SEM was only measured at T2.

The average pulse rate during injection (T2), in the computer-controlled injection technique (113.5 ± 1.88 bpm) was significantly greater than that of the two-stage injection technique (111.5 ± 1.77 bpm) (P=0.030). Pulse rate was also significantly less at T3 when the two-stage injection technique was used (P=0.003). There was a statistically significant difference between mean pulse rate values measured at T1 and T2 (P=0.007) as well as T1 and T3 (P=0.009). There was a statistically significant difference between the frequency of Faces criterion of the two techniques when during injection (T2) (P=0.004). Regarding SEM Pain Sclae, a significant difference was not found between the two techniques (P=0.529).

The two-stage injection technique demonstrated superior results in terms of pain and stress control compared to the computer-controlled injection technique. This technique seems to be a favourable method for achieving local anaesthesia with minimal pain and stress in is children.

Job satisfaction among dental faculty members has remained relatively understudied. This study aimed to evaluate the level of job satisfaction of faculty members teaching at dental schools.

In this descriptive cross-sectional study, data collection was conducted using the persian version of the Smith, Kendall, and Hulin job descriptive index questionnaire. The questionnaire was distributed among faculty members attending dental school at Tehran, Shahid Beheshti, Shahed and Islamic Azad Medical University from January 2018-2019. The survey collected demographic information and assessed satisfaction in six domains: salary and benefits, opportunities for promotion and personal growth, supervision and communication, mental conditions and job security, physical conditions and the nature of work. Data collection involved rating their satisfaction in each domain on a 5-point Likert scale. Kruskal–Wallis, Independent samples T-test and Spearman’s Correlation Coefficient were used for statistical analysis.

A total of 164 faculty members completed the questionnaire. The majority of participants (%78.4) showed a moderate level of overall job satisfaction. A moderate level of satisfaction was observed in salary and benefits (%46.3), opportunities for promotion and personal growth (%48.3), supervision and communication (%70), mental conditions and job security (%64.6), physical conditions and the nature of work (%54.3). There was a statistically significant relationship between age and the scores for the “supervision and communication” and the “salary and benefits” domains (P<0.05 for both). Older age resulted in higher “salary and benefits” scores and lower “supervision and communication” scores.

The majority of faculty members exhibited a moderate level of overall job satisfaction. The domain with lowest satisfaction score was “salaries and benefits” which should be addresses through careful assessment and meticulous planning.