Journal of Dental Medicine

Background and Aims: Erosion is the chemical dissolution of a tooth by acid without bacterial involvement. The purpose of the current study was to investigate the effect of resin infiltration (Icon), MI paste plus, and Nd:YAG laser on the enamel microhardness.
Materials and Methods: 40 enamel samples were obtained from the third molar tooth. Primary microhardness was measured in all specimens. Then, erosion was created using hydrochloride acid on the surfaces of enamel and the microhardness values were measured. The samples were randomly divided into four groups. G1: MI paste plus, G2: MI paste plus+ Nd:YA laser, G3: ICON without etching, G4: ICON with etching. Erosion was induced again by hydrochloric acid and then subjected to thermocycling. Finally, the microhardness of the samples was measured. Statistical analysis was performed using SPSS23 software, one-way ANOVA, multiple Tukey and T-test comparisons. P<0.05 was considered as a significant level.
Results: The microhardness increased in the third stage compared to the second stage in all groups, which was statistically significant (P<0.000). Also, the comparison of the increase of microhardness among groups, except second group with the fourth group, was statistically significant.
Conclusion: All the materials used in this study significantly increased the microhardness of the eroded enamel.

Background and Aims: Periodontitis is one of the most common causes of damage to the gums and retaining structures of the teeth. Matrix protein, a metalloproteinase, is known as intermediate collagenase and the enzyme collagenase fibroblast, which is encoded in humans by the MMP-1 gene. The aim of this study was to investigate 1G/2G polymorphism in the MMP-1 gene and its association with the periodontal disease in the Iranian patients.
Materials and Methods: In this study, 50 patients with periodontal disease and 50 patients were selected as the control group in Kerman city. DNA was extracted from a person's blood sample using a kit. The desired primers were controlled by the NCBI site. Then, with the Tetra arms PCR technique, the desired polymorphism was multiplied. In the next step, the samples were transferred to electrophoresis gel and examined. The results were analyzed with SPSS software using T-test or Squer Chi-(X²).
Results: The percentage of 1G/1G genotype in the patients group was 8% and for the controls group was 0%. The percentage of 2G/2G genotype for the patients group was 24% and for the controls group was 18%. In addition, the 1G/2G genotype frequency was 68% for the patients group, and for the controls group was 82% (P=0.83). The results of Tetra-arms PCR genotyping of the samples were confirmed by sequencing.

Conclusion: The findings indicated that in Iranian patients, MMP-1 -1607 1G/2G (rs1799750) was not significantly associated with periodontal disease. It is recommended to take more samples from different parts of Iran to confirm the results.

Background and Aims: The inferior alveolar nerve block (IANB) is the most frequently used technique for mandibular anesthesia. Due to the many factors which can cause its failure, the aim of this study was to evaluate the efficacy of experience and knowledge in the success rate of IANB technique.
Materials and Methods: : In this study, 115 students of Shiraz Dental school were participated in two groups. One group contained 53 novice students and another group 62 students with one year experience in IANB injection. Each student accomplished injection once and then success or failure of the injection was examined. In order to evaluate the students’ knowledge, each student was asked to fill out a questioner including 6 questions related to the instruction of the injection. Data were then collected, coded, and analyzed by SPSS18 using Chi square with a significant level of 0.05.
Results: The rates of knowledge in novice and experienced group were 71.6% and 86.3%, respectively. The success rates of IANB were 47.1% in novice group and 64.3% in experienced group. The success rates of IANB and knowledge were significantly higher in the experienced group compared with the novice group. (P=0.02 and P=0.01, respectively) There was no significant difference between male and female (P=0.06).
Conclusion: The results showed that knowledge and experience could play an important role in the success rate of IANB technique.

Background and Aims: Due to the very high importance of assessing the clinical performance of students, choosing the best assessment tool and method is one of the most important goals and tasks in medical education. The objective of this study was the development of a checklist for the assessment of dental students’ clinical skills of Tehran University of Medical Sciences, in the clinical complete denture course. The second aim was to determine the validity and reliability of the checklist, and The third aim was the evaluation of raters’ and students’ satisfaction.
Materials and Methods: The checklist was developed in expert panel sessions, and the validity and reliability of the checklist were assessed with CVI (content validity index) test-retest and inter-rater reliability methods, respectively. Students (n=15) were evaluated with a developed checklist. At the end of the session, the satisfaction level of staff and students were assessed. The obtained information was reported descriptively with the expression of mean and standard deviation and in the form of relative and absolute frequencies.
Results: The content validity index (CVI) of the checklist was 0.96. The reliability of the checklist confirmed with a high Intraclass Correlation Coefficient (>0.8) (between 0.82-0.97) (P<0.05). The coefficient of agreement in inter-rater reliability was 0.99 (between 0.991-0.998). Raters’ and students’ satisfaction earned a high percentage of satisfaction.
Conclusion: The designed checklist has the optimal features of a good students’ clinical performance assessment tool; it seems that using this checklist can be an excellent alternative method to a global rating scale to assess the clinical skills of dental students in the complete denture courses.

Background and Aims: Immediate implant placement following tooth extraction is a treatment with many advantages. Alveolar bone preservation after immediate implant, need minimum of 2 mm thickness in buccal bone plate. The aim of this study was to evaluate the thickness of buccal cortical bone of maxillary premolars by Cone Beam Computational Tomography (CBCT) technique.
Materials and Methods: In this descriptive epidemiological study, Cone Beam Computed Tomography image was obtained from 29 patients (male and female) referred to the radiology department of Jundi Shapoor dental school of Ahvaz from 1393 (Mehr) to 1394 (Shahrivar) for implant insertion insertion. The thickness of buccal cortical bone was measured in 3 and 5 mm apical to the CEJ and root apex, perpendicular to the longitudinal axis. All the measurements were done by two oral and maxillofacial radiologists, separately. Data were analyzed by SPSS22 software, using descriptive statistics, and T-test.
Results: The thickness of buccal cortical bone in second premolar was significantly more than 1 mm (P=0.001), but in first premolar, the thickness was close to 1 mm with a non-significant difference (P=0.29).
Conclusion: The results of this study showed that immediate implant insertion could be done in the maxillary second premolar area with more predictability compared to the first premolar area.

Background and Aims: Some of the post-operative complications of impacted third molar surgery, one of the most prevalent surgeries in oral field, are known to be infection, erythema, trismus and pain. Antibiotic prescription to prevent post-operative infection under some particular circumstances, is acceptable but under debate considering their disadvantages. In the present study, we examined the infection rate in patients taking no or 2 types of antibiotics distinctively after impacted mandibular third molar surgery.
Materials and Methods: In this double blind clinical trial, 90 patients within the age range of 18 to 34 were dedicated to 3 groups (group 1: 2 capsules of placebo on surgery day and 1 for 4 days, group 2: Amoxicillin 500 mg every 8 hours for 5 days, group 3: Azithromycin 250 mg, 2 capsules on surgery day and 1 capsule for 4 days). All subjects were treated by a sole surgeon, protocol, surgical technique, and flap type and the same amount of osteotomy. In addition to aforesaid drugs, the patients received chlorhexidine and Gelofen 400 mg. At the day 7 postoperative, cases were examined to evaluate the infection (trismus, erythema and halitosis). Data were analysed using Chi-Square test and the groups were compared by Kruskal-Wallis test.
Results: Three signs of infection (halitosis, erythema and trismus) were compared in patients. Symptoms of halitosis and erythema were more indicated in first group, but the ultimate statistical analyses among the 3 groups from halitosis and erythema viewpoint showed no significant difference (P=0.072, P=0.149). Although, no severe trismus was reported, the most moderate trismus incidence was in group 2 and mild trismus was exhibited in group 1. In group 3, no trismus occurred. On the whole, the trismus frequency among groups was statistically significant (P=0.004).
Conclusion: Comparing infection symptoms of the three study groups emphasized the fact that only trismus rate was statistically significant (P=0.004). On balance, the results of this study indicated that antibiotics did not have significant impact on the reduction of most postoperative complications, especially on infection.

Background and Aims: Elastomeric chains are known as a current device with the purpose of dental movement in orthodontic treatments. The aim of this study was to compare the elastomeric behavior and force degradation rate between different elastomeric chains existing in Iran in different time durations.
Materials and Methods: 11 different elastomeric chains used in this study were: Class One, ASTAR, G&H, TSNPT, MIB (French and Chinese type), Ultra Chain and both American, Ortho Technology (simple and memory type). All chains were stretched upon to exert 150 g force and then force degradation rate in 6 time duration
(1, 3, 24 hours and 3, 7, 21 days) and modulus of elasticity (MOE) in 2 time duration (start and 21 days) were investigated. All Data were analyzed statistically by ANOVA, Tukey, Games-Howel tests.
Results: All chains up to the 21th day showed a significant decrease in MOE except for the G&H, ClassOne, simple orthotechnology and a significant force degradation except for the American (memory type). The most significant force degradation rate was in ASTAR gray (P<0.05) and the least in MIB (French), Ultra Chain, and American (P<0.05).
Conclusion: All chains showed significant time-dependent force degradation (mostly in the first day). Only, this rate was not significant in any time duration for the American (memory). In all groups, the most force degradation rate belonged to ASTAR gray and the least to Ultra Chain, MIB (French) and American after 21th day.

Background and Aims: Periodontal diseases are prevalent and are not only a threat to oral and dental health of patients and community, but also affect the quality of life associated with oral health. Therefore, the present study aimed to evaluate the effects of non-surgical periodontal therapy on the quality of life associated with oral health in patients with periodontitis and gingivitis.
Materials and Methods: 47 patients with gingivitis and moderate to severe chronic periodontitis referred to the periodontology department of Yazd Dental School in 2019 were studied. OHIP-14 validated questionnaire was used to assess the quality of life related to oral health. At the beginning of the study, both groups completed the questionnaire. Then scaling and root planning for periodontitis group and scaling for gingivitis group were done. Patients completed the questionnaires again 9-12 weeks after periodontal treatment. Data were analyzed by SPSS software version 22 using independent T-test, Chi-square, Mann-Whitney and Wilcoxon tests.
Results: The mean score of quality of life in patients with gingivitis was 19.18±11.68 before the treatment and 13.26 ±11.41 after treatment. The mean score of quality of life in patients with periodontitis was 23.29±9.80 before treatment and 13.95±9.68 after treatment. All the differences between groups before and after treatment were statistically significant (showing better quality of life after the treatment) (P<0.05). There was no statistically significant difference between the mean score of quality of life related to oral health in the studied patients according to the age and sex (P>0.05).
Conclusion: According to the results of this study, treatment of periodontal diseases improves quality of life related to oral health in patients with gingivitis and moderate to severe chronic periodontitis.

Background and Aims: Pre-cancerous lesions of the oral mucosa as important malformation need acceptable knowledge of dentists. The purpose of this study was to determine the knowledge of Isfahan city general dentists about pre-cancerous lesions of oral cavity.
Materials and Methods: This descriptive cross-sectional study based on validated questioner form was performed in 115 general dentists in Isfahan City in 2019, associated with sex and year of graduation from general dentistry course. The mean score was in the range from 0 to14. Data were recorded in Microsoft Excel and then analyzed by SPSS. In order to compare quantitative variables, independent T–Test, One-Way ANOVA and Mann-Whitney was used. P≤0.05 was considered as significant.
Results: The mean age in the participants of: lower than 5 years, between 5-10 years, and more than 10 years of graduation were 28.6±4.9, 30.6±4.0 and 47.9±10 years old, respectively. In total population, the mean score of knowledge was 5.97±2.79. There was not any significant difference between the mean score of knowledge in women when compared to men (5.96±2.99 versus 5.98±2.6; P=0.58). The mean knowledge score in the participants of: lower than 5 years, between 5-10 years, and more than 10 years, of graduation were as follow: 7.8±2.2 versus 5.8±2.9 versus 4.4±2.1, correspondingly (P≤0.05).
Conclusion: For the early diagnosis of pre-cancerous lesions of the oral cavity, retraining program based on oral cavity pathology courses is recommended for the dentists in Isfahan city.

Background and Aims: Enoxolon is a natural licorice and its formula is similar to cortisone. The aim of this double blind randomized match control clinical trial, was to analyze the effect of Arthrodont toothpaste containing 1% Enoxolone on dental plaque, gingival inflammation, and bleeding indices.
Materials and Methods: 40 patients who had gingivitis were selected. They were instructed to brush their teeth twice daily for three minutes then massage the gums with pastes for one minute and then wash their mouths. The patients were divided into two groups: The Arthrodont toothpaste containing Enoxolon, was given to the study group and the Crest toothpaste free of Enoxolon, was given to the control group. At the beginning of the study and after 21 days, plaque, gingival, and bleeding indices were measured. The statistical analyses were done by Paird T test, T test and nonparametrical analysis of Wilcoxon and Mann-Whitney.
Results: In both groups, the three indices decreased significantly. Comparing between the two groups, the gingival and bleeding indices had significantly decreased in the study group (Arthrodont toothpaste) compared to the control group (Crest toothpaste). However, no significance difference in the plaque index between the two groups was found (P=0.143).
Conclusion: The results of this clinical study showed that Enoxolon had anti-inflammatory effect on gingivitis.

Background and Aims: The self-adhering composites were introduced to reduce the chair time and minimizing handling errors. They can be bonded micromechanically to the dental structure without the need for separate adhesive application. Since there is limited information about bonding performance of this type of composite, the aim of this study was to evaluate the microleakage of enamel and dentin margins compared to the conventional adhesive systems.
Materials and Methods: 30 intact premolars were selected and on their buccal and lingual surfaces, standardized class V cavities with the occlusal margin in enamel and gingival margin in dentin were prepared. Then according to the materials used, the specimens were randomly divided into three groups including: 1) Vertise flow, 2) SE bond + ValuxTM Plus, and 3) Single bond + ValuxTM Plus. After final polishing of the restorations, the specimens were subjected to 1000 thermal cycles of 5±2 and 55±2°C and after that dye penetration was examined by stereomicroscope. The collected data were statistically analyzed using Kruskal-Wallis test and Mann-Whitney test
Results: The lowest rate of the occlosal microleakage was related to group 2 (P<0.05) and there was no significant difference between groups 1and 3 (P=0.58). Also, no significant difference was found in the gingival microleakage among the three groups (P=0.23). On the other hand, in each group, the gingival microleakage was significantly higher than occlosal margins (P<0.05).
Conclusion: According to the results, sealing ability of self-adhering composite is comparable with that of the conventional adhesives.

Background and Aims: Different materials have been used to make dentures during different years. Teeth used in making dentures should have appropriate physical and mechanical features to meet the needs of masticatory functions, meanwhile having desired beauty. The aim of the present study was to determine the frequency of previous denture material and f its form and the duration of use in patients referring to the prosthesis department of Tabriz Dental School during 1385 to 1395.
Materials and Methods: This cross-sectional descriptive study was performed on the basis of paraclinical examination on all cases of removable prostheses in patients referring to the department of prosthodontics of Tabriz University of Medical Sciences from 1385 to 1395. Based on the files, the percentage of frequency of previous denture type, previous denture tooth material, previous tooth form, previous time of denture using during the day and night were statistically evaluated by SPSS20 software.
Results: The results of this study showed that out of 471 patients, 151 people used removable dentures. A study of previous denture material showed that the frequency of using dentures containing resin teeth with 48.3% was much higher than porcelain teeth with 13.8. Examination of the dental form showed that in 13.8%, the dental form was with a cusp, in 48.3% without a cusp and in 37.9% the type and form of the teeth were not clear (P<0.01). Evaluations showed that 24.1% of patients used their dentures only during the day and 41.4% of patients used them overnight.
Conclusion: A 10-year study of patients with dentures at the Tabriz School of Dentistry documented the common use of resin teeth denture, as well as overnight use of them and the non-cusp form of denture teeth.

Background and Aims: Dental caries is a common childhood disease with a considerable effect on quality of life. In visually imparted children oral health and dental treatments are more complicated. To prevent oral diseases, it is necessary to educate visually impaired children. The aim of this study was to evaluate the effects of oral hygiene training on oral health status in visually impaired children.
Materials and Methods: In this semi experimental study, 50 visually impaired children 8 to 12 years old were systematically recruited from visually impaired exceptional schools. Participants were randomly allocated into two control and study groups (25 each). Sillness and Loe plaque index was recorded in all 50 children at baseline and after intervention and follow up periods. The study group received oral hygiene instructions (rolling toothbrush technique) using Braille booklets and hand over hand education. The training repeated three times with two weeks’ intervals and at the end Plaque Index was measured in both groups ANOVA, T-test and Mann Whitney tests were employed to compare intra and inter groups statistical analyses. (α=0.05).
Results: At the baseline, the mean plaque index score in the study group was 2.03±0.52 which decreased to 1.23±0.34 at the end of the intervention (P<0.001). Initially, in control group, the Plaque Index score was 2.26±0.49 which was 2.19±0.44 at the end of the study. Changes in Plaque Index scores were statistically significant between two groups. (P<0.001).
Conclusion: It was concluded that oral hygiene instructions using visually impaired specific training methods improved Plaque Index in these children.

Background and Aims: Anxiety is a common problem in patients referred to dental clinics that is associated with underlying personality factors. The purpose of this study was to determine the role of personality traits in predicting dental anxiety.
Materials and Methods: In this study, 211 patients (110 men and 101 women) referred to the dental clinics in Tabriz in 2019, were selected by available sampling method. The method of this study is descriptive- correlative. The research instrument was a short-form NEO-personality inventory and a dental anxiety inventory. Data were analyzed by correlation and regression analysis using SPSS22.
Results: The research findings showed that the average age of women and men was 30 and 31 years, respectively. 49% of the clients were single and 51% were married, and the education of most of the clients was undergraduate. Also, Regression analysis showed that dental anxiety had a positive correlation with personality trait of neuroticism (r=-0.49, P<0.01), and it had a negative relationship with extroversion (r=-0.19, P<0.05), agreeableness (r=-0.21, P<0.01), consciences (r=-0.35, P<0.01); and two factors of neuroticism (t=4.71, P<0.01) and conscience (t=2.44, P<0.01), and predicted dental anxiety (P<0.05).
Conclusion: From the results, it can be concluded that anxiety with a sense of danger that was observed in many people in the face of dental interventions, occurred within individuals. By recognizing root factors, it can be partly strengthened by deterrent and suppressor personality factors for anxiety, and thus, taking advantages of the dental services and preventing from avoiding dental treatments.

Background and Aims: Interest and satisfaction of students toward their field of study has important role in knowledge promotion, future activities, and also healthcare of country. This study aimed to evaluate the attitude of dental students toward their field of study and also their future career.
Materials and Methods: This cross-sectional descriptive study was based on a standardized researcher designed questionnaire in 2018. Demographic data was collected and questions were based on the attitude of students toward their field of study and their future. ANOVA and Backward stepwise regression methods were used for statistical analysis. Significance level was determined at 0.05.
Results: In this study 62.2% of responders were female and 37.8% were males. Students chose dentistry under the influence of following matters consecutively: high income, recommendation of people around and self-interest. Girls compared to boys, were significantly influenced more by self-interest and also had more interest compared to boys for working in dentistry (P<0.05). Also, most of students were anxious about the increase in the number of dental students.
Conclusion: Students had positive attitude toward their field of study and their future. They were interested in working in this field but factors such as not having enough familiarity toward this field and also an increase in the number of students in recent years created some worries for them.

Background and Aims: Adding nanoparticles to dental composite resins, could reduce bacterial adhesion and secondary caries. Thermocycling can resemble in-vitro conditions to the oral environment. The aim of this study was to determine the effect of thermocycling on the microleakage of a mixture of copper oxide nanoparticles and flowable composite.
Materials and Methods: In this in-vitro study, 88 premolar teeth were divided into eight groups based on the application of copper oxide nanoparticles with concentrations of 0.1% and 0.3% w/w and thermocycling by 0, 1000, 5000 and 15,000 cycles. The occlusal grooves of the teeth were sealed with the mixture of flowable composite and copper oxide nanoparticles, and the teeth were thermocycled. Next, the teeth were immersed in methylene blue 2% solution for 24 hrs and were cut and the microleakage was evaluated by a stereomicroscope (hp/USA). Data were analyzed using Kruskal-Wallis and Mann-Whitney tests at the significance level of 0.05.
Results: In the groups with 0.1 % copper oxide nanoparticles, the mean microleakage increased significantly with increasing the number of thermocycling rounds (P=0.032). The difference in the microleakage between the groups exposed to 0 and 15,000 termocycling was significant (P=0.019). However, thermocycling had no significant effect on the microleakage of groups with concentration of 0.3% (P=0.780). The specimens subjected to the 0, 1000, 5000 and 15000 thermocycling in two concentrations of copper oxide nanoparticles showed no significant difference in the microleakage.
Conclusion: In groups containing copper oxide nanoparticles with a concentration of 0.1%, the microleakage increased by increasing the number of thermocycling up to 15,000 cycles compared to the control group. However, this did not have significant effect for the concentration of 0.3% copper oxide nanoparticles.

Background and Aims: Dental anxiety and fear can act as a barrier to seek dental care leading to insufficient oral health in people. The aim of this study was to determine the relations between dental fear and anxiety with dental caries status (DMFT) and clinical consequences of untreated dental caries (PUFA) among the adult patients referred to the faculty dental clinic of Tehran University of Medical Sciences.
Materials and Methods: In this cross-sectional study in 2019, the patients above 18 years old were assessed. Two standard questionnaires, Dental Fear Scale (DFS) and Modified Dental Anxiety Scale (MDAS), were used to assess the scores of dental fear, and dental anxiety, respectively. The demographic data of the patients were recorded. Dental caries status and clinical consequences of untreated dental caries, using DMFT and PUFA, respectively, were measured. Pearson correlation coefficients and multiple linear regression model (Backward method) were used for statistical analysis.
Results: Totally, 283 patients with the mean age of 38.6±11.8 years old participated. The mean scores of MDAS, and DFS were 12.04±4.49, and 41.33±16.87, respectively. Educational level (P=0.03, β=-0.14) and marital status (P=0.01, β=0.17) had significant relationships with MDAS scores. Moreover, a significant relationship was found between marital status and DFS scores (P<0.001, β=0.25). Significant correlations were found between dental anxiety level and D (P<0.001, r=0.36) and M components (P=0.02, r=0.14) of DMFT index. Moreover, there was a significant correlation between dental anxiety and U components of PUFA index (P=0.045, r=-0.12). Furthermore, the correlations between dental fear and D and M component of DMFT were significant (P<0.001, r=0.36; P<0.001, r=0.23; respectively).
Conclusion: Dental anxiety and dental fear were infrequent in the studied population; however, significant relationships were found between dental anxiety and dental fear with dental caries indices. Therefore, it was concluded that the more MDAS and DFS scores, the worse dental caries status.

Background and Aims: With increasing age and inability to maintain good oral hygiene, the chances of tooth loss increase and the need for dental implants will increase in the future. It also increases the risk of developing peripheral implants, especially at older ages in the failure of implant treatments. Recently, the high prevalence of cardiovascular disease and peri-implantitis in the elderly has been reported. The aim of this study was to investigate the effect of cardiovascular disease on the peri-implantitis in people with failed dental implants.
Materials and Methods: In this retrospective study, the files of patients referred to Shahid Montazeri Dental Clinic from 2009 to 2018 whose their failed implants were extracted, were collected. There were a total of 793 people with failed dental implants. The variables of this study were demographic information including age and sex, health status in terms of cardiovascular disease and peri-implantitis, which were identified and then statistically analyzed by examining the files of patients with these two variables. Data were statistically analyzed by SPSS25 statistical software and Chi-square was used to determine the effective variables.
Results: A total of 793 patients had failed dental implants, including 368 women (46.4%) and 425 men (53.6%) with an average age of 50.79 years. 42 patients (5.3%) had heart disease and 44 (5.5%) had peri-implantitis. According to the Chi-squared test, the significance level was less than 0.05 (P=0.011).
Conclusion: The results of this study showed that the cardiovascular disease and peri-implantitis were significantly related.

Background and Aims: Radiography is one of the most important para-clinical methods in diagnosing and selecting treatment in dentistry. Due to the potential dangers of X-rays for patients, the professional responsibility of the dentist requires that unnecessary radiographs to be avoided. The aim of this study was to investigate the awareness of dentists in Zanjan about the principles of radiation protection in 2019.
Materials and Methods: This cross-sectional study was performed on 107 general dentists and specialists working in Zanjan and the questionnaires were distributed among them. The level of awareness of dentists in 27 questions of radiographic prescribing questionnaire was evaluated and in each of the mentioned questions, their gender, age, work experience, participation in retraining, having X-ray machine in the field of dentistry and type of activity were evaluated. Data were analyzed by Chi-square test, Independent T-test, and ANOVA using SPSS software version 22.
Results: The results showed that the level of knowledge of general dentists about the principles of radiation protection (14.35±3.08) was lower than that of specialized dentists (17.19±2.35). Those who participated in retraining workshops (13.85±2.99) had less knowledge than those who did not (15.97±3.97), which was statistically significant (P<0.05); However, there was no significant difference in the dentists' knowledge about the principles of radiation protection based on gender, age, type of activity, having an X-ray machine at the place of treatment, and history of clinical experience (P≥0.05).
Conclusion: Awareness of dentists at various levels was moderate. Therefore, designing and holding more purposeful retraining courses to maintain and improve the level of awareness of dentists according to the guidelines provided by the authorities, still seems to be necessary.

Background and Aims: Regarding the need for social accountability in dental education, community-based dental courses has been established to improve the oral health of the community and compensate the shortcomings of the health system. Due to the importance of evaluation, the aim of this study was to determine the dental students’ attitudes and believes in the last year of their study towards the community-based dental education.
Materials and Methods: This cross-sectional study was performed on 159 dental students in the sixth year (October and February, 2018) of Isfahan dental school by census. These students took the relevant questionnaire, which was developed by researchers in three sections of “attitudes toward field activities”, “lessons and experiences of field activities during dentistry training” and “barriers and problems of field activities”. Its content and face validity was confirmed. They completed it on their own and after collecting information and descriptive analyzes, the relationship between the gender and entry group with attitude scores was analyzed by Mann-Whitney U test.
Results: Out of a total of 102 questionnaires which were answered (response rate of 64%), half of the students believed in the need to provide dental services in the form of mobile/outreach services for the community. 90% of the students agreed with the combination of field education with routine education in the dental schools. They also considered these services as an opportunity to use their experiences and knowledge to promote oral health in the community. 84% of them believed that their self confidence improved while providing services outside the faculty. In many of the propositions in the field of attitude to provide service in the field, a significant percentage (50 to 60%) did not have an opinion.
Conclusion: There was a good and positive aspects in many areas of attitude toward providing services in social fields as well as attitude towards the lessons learned from community-based dental education. However, we should consider the attitude-emotional aspects of educational objectives in the community-based courses in dental schools.