Journal of Dental Medicine

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: 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: 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: 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: 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: 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.

Background and Aims: A significant percentage of children with dental caries require, hospital dentistry and their parents do not have much information in this regard. The aim of this study was to determine the knowledge, attitude and practice of pediatricians in hospital dentistry in Isfahan Province.
Materials and Methods: This cross-sectional study was performed on 100 pediatricians working in Isfahan. The self-administered questionnaire included demographics of doctors and 19 questions for assessing the knowledge, attitude and practice of pediatric practitioners about hospital dentistry under general anesthesia. Raw data were analyzed by Chi-square test using SPSS software version 23.
Results: 100 pediatricians with an average age of 44.1±5.7 years (57% male) completed the questionnaire. 53% of the pediatricians had a high level of awareness about hospital dentistry and 42% about its related guides. 66% practitioners had a favorable attitude toward general anesthesia and costs, while 71% considered the parents' awareness were poor about hospital dentistry. Only 43% of pediatricians performed oral examinations in their daily visits, and 17% had a referral for hospital dentistry. Male pediatricians aged from 35 to 45 had a higher level of knowledge about hospital dentistry. The attitude and practice of pediatricians did not have a significant relationship with their age. Meanwhile, male pediatricians had better performance in oral and dental examination and referral for hospital dentistry (P=0.15).
Conclusion: From the results of this study, there is a need for a serious improvement in the level of knowledge, attitude, and practice of pediatricians in the field of hospital dentistry.

Background and Aims: Removable partial denture (RPD) is a common treatment to restore partially edentulous areas; however, a limited number of studies have been made on oral hygiene habits among patients with RPD. The aim of this study was to evaluate the patients’ knowledge about various cleaning methods of RPD to consciously improve hygienic habits of the patients.
Materials and Methods: This study was a cross-sectional study performed on 96 RPD patients referred to Jundishapur faculty of dentistry from 1395 to 1396. Demographic data namely age, sex, level of education, and other information about general health status, duration of dentures usage, and denture cleaning frequency were taken by the census through questionnaires. The descriptive statistics, chi-square, and T-test were used for statistical analysisof data (P<0.05).
Results: The patient age, sex, and smoking habits had significant effects on the prosthesis maintenance habits (P<0.05). The patients over 50 years of age, females, and nonsmokers significantly preferred dipping method over other RPD storage methods (P<0.05). The frequency of denture cleaning was significantly greater in males (53.3%) compared to females (23.9%) (P<0.05).
Conclusion: According to the results of this study, most RPD patients did not clean their dentures appropriately and have little knowledge on how to maintain and clean them. Regular and periodic recall and written instructions might be helpful to improve patients' awareness on proper cleaning and maintenance of partial dentures.

Background and Aims: Information collection about the malocclusion and oral health in blind children is essential to plan for their education in schools. Therefore, this study aimed to evaluate the status of malocclusion and oral health among blind children and teenagers in Mazandaran, Iran.
Materials and Methods: The population of this included 150 blind children and teenagers aged from 10 to 18 years who were referred to the public and private centers cities including Sari, Babol, Freydoonkenar, and Babolsar in Mazandaran, Iran in 2019. Information on maxillary occlusion status, oral hygiene index, and DMFT index was extracted through clinical examination. Data were analyzed using SPSS23 software by ANOVA and Chi-square tests in addition to the descriptive statistics.
Results: The mean DMFT was 10.25 (SD 4.67). Oral hygiene status was good in 16% of participants, moderate in 82%, and poor in 2%. There was no significant difference between girls and boys in terms of oral hygiene status (P=0.5). In all cases, 35.8% had class I malocclusion, 29.8% had class II malocclusion, and 14.6% had class III malocclusion. Class II malocclusion was more common in girls and class I in boys (P=0.01).
Conclusion: Dental caries and occlusal abnormalities were common among blind children and adolescents living in Mazandaran province. Addressing the oral and dental needs of the blind should be a priority for health policymakers in this province in Iran.

Background and Aims: Providing quality services is one of the important goals of the health system. Dental services and treatments are expensive. The aim of this study was to investigate the factors influencing the perceived quality of dental treatment services.
Materials and Methods: This descriptive-cross study conducted in 2 qualitative-quantitative phases. Data were collected using interviews and pairwise comparison matrix with 20 dentists working in NAJA dental clinics who were selected by targeted sampling. The validity and reliability of the interviews were determined by long-term engagement of their peers and negative case analysis. The validity of the pairwise comparison matrix was determined through the incompatibility rate (>0.1). Data were analyzed by coding and effect intensity tests (R+J), descriptive statistic test (mean, standard deviation) using SPSS23, Maxqda and matlab R2017b.
Results: Content analysis of the interview showed that tangible factors, assurance, trust, and empathy are the factors affecting the quality of dental treatment services. In the second phase, data analysis showed that trust and empathy (28.204), assurance (24.356), and tangible factors (17.798) are the most to the least important factors in the quality of dental treatment services (P=0.1).
Conclusion: Trust and empathy were the most important factors in the quality of dental treatment services. Managers of dental clinics and dentist need to improve the quality of dental treatment services by emphasizing respect for patients in accordance with the promise to act in the field of providing treatments to patients.

Background and Aims: Human ergonomics or engineering with proper design and change of work and requirements creates the most productivity based on human physiology. The purpose of this study was to determine the level of awareness of dental students of Isfahan University of Medical Sciences about the basic principles of ergonomics in dentistry.
Materials and Methods: In this descriptive-analytical, sectional study, a questionnaire containing 10 questions was distributed and completed by easy sampling method among 74 final year students of the general doctorate of Isfahan school of dentistry. After collecting the questionnaires, the students were given an educational pamphlet. To evaluate the questionnaires, each correct answer was given a score of one and the wrong answers were given a score of zero. Data were analyzed by T-test, Kai Square, and Mann-Whitney statistical tests using SPSS23 software. P<0.05 was considered as a significant level. P<0.05 was considered as a significant level.
Results: The average score of the knowledge of principles of ergonomics was intermediate (6.23±1.25). Student knowledge was not significantly different based on the student gender (P=0.25) and academic semester (P=0.059). Also, 55% of students had a history of muscle pain that did not have a significant relationship with gender (P=0.258) and average score of the knowledge (P=0.288).
Conclusion: Unfortunately, ergonomics cannot be considered part of the principles of dental education and even later. Musculoskeletal pain is one of the most common complaints of dentists and is a factor in reducing their quality and function. Therefore, it seems that training and evaluation of ergonomic principles in dental education is necessary.

Background and Aims: Poly methyl methacrylate (PMMA) is still the most commonly used material in prosthetic dentistry. However, there are problems with the mechanical properties of this type of material including low flexural strength. Addition of nanoparticles into the polymer is one way to improve the mechanical properties of acrylic resin. In the present study, the effect of silicon dioxide (SiO₂) nanoparticles addition into the heat-cured acrylic resin in different concentrations was investigated. Because of the controversy had been observed in previous articles, the aim of this study was to investigate the mechanical properties of PMMA/SiO₂ nanoparticle obtained from different percentages of SiO₂.
Materials and Methods: In this in-vitro study, acrylic resin specimens containing 0, 1, 3 and 5% silicon dioxide (SiO₂) were prepared. The specimens were placed inside the gypsum molds and placed under pressure for three times. The mold cured in boiling water for 30 min. A trimmer was used to remove the additives. Sandpapers with 180, 320 and 600 grains of silicon-carbide were used for final finishing and polishing. Finally, the flexural strengths were measured using a universal testing machine. Data were finally analyzed by ANOVA and Tukey tests at a significant level of 5% using SPSS software.
Results: The mean flexural strengths and standard deviations of control group, 1% filler, 3% filler, and 5% filler, were 57.24±8.30, 69.98±7.26, 60.16±9.18, and 61.59±9.28 MPa, respectively. After comparing significant values between each group with the control group, a significant difference was observed between the control and 1% filler group (P=0.021). However, no significant difference was observed between 3 and 5% fillers with the control group or each other. The significant differences (P-value) between 3% filler and control group were 0.892 and between 5% filler and control group was 0.975.
Conclusion: The results of the present study showed that the use of low percentage of silicone dioxide (SiO₂) nanofiller could improve the flexural strength of poly methyl methacrylate acrylic resin.

Background and Aims: Pulpal exposures originated from the external cervical root resorptions have major effects on the treatment and prognosis. Therefore, the aim of this study was performed to compare the two different imaging systems-digital radiography with PSP (Photostimulable Phosphor) sensor in three horizontal different views and CBCT (cone beam computed tomography) images to assess the pulpal exposure in simulated cavity of external cervical root resorptions that was performed in 1398 in the School of Dentistry of Azad University.
Materials and Methods: 40 intact maxilla anterior teeth with straight roots were included. Teeth were randomly divided to two groups (20 teeth with and 20 without pulpal exposures). Each sample was assessed using PSP digital radiography (in 3 horizontal angles) and CBCT image system, to detect the presence of pulpal exposures. False negative and false positive results in 2 imaging procedures were judged with ratio test.
Results: The results showed in CBCT (P.P.V=85.7%) and (N.P.V=89.5%), and in digital intraoral radiography (P.P.V=80%) and (N.P.V=80%) in proximal defects. Ratio test showed that there were no significant differences in the proximal defects (P<0.4).
Conclusion: The results showed that there were no significant differences in detection of exposure in the proximal surfaces between two imaging systems.