Journal of Dental Medicine

Background and Aims: Acurate measurements of variables are crucial in epidemiological studies. Therefore, even the best design cannot prevent bugs caused due to the lack of reliability and validity measurement in studies. The aim of this study is to determine the validity of teeth-canal measurement.

Materials and Methods: This methodological study used available data of patients referred to dental clinics at Hamadan University of Medical Sciences in Hamadan with sample size or 58 cases in 2012. In order to determine the reliability of measuring the length of canals and introduce the most appropriate measure met of the actual data, Bland-Altman plot and intraclass correlation coefficient (ICC) were used and finally compared.

Results: In this study, the mean ± SD of channel length in the apex locator Root ZX were 21.93 ± 2.28 mm and in X-ray PA were 22.4 ± 2.38 mm. ICC between the length of canals by the apex locator and radiographic in all teeth was 0.989. Bland-Altman plot showed that absolute agreement between the two methods of measurement.

Conclusion: The findings of this study ensure dental professionals that measuring the length of channels by PA method is more practical and easier and prove different approaches of the reliability and validity. However, we recommend using ICC and Bland Altman methods due to their informative nature and consideration of absolute agreement instead of consistency.

Background and Aims: In recent years, dental implants have received special attention in dentistry. Due to the remarkable success of predictable dental implants, there is growing interests in the scientific community from descriptions of implant success toward identify factors associated with implant failure. The purpose of this study was to identify the risk factors associated with implant failure in an objective and statistically valid manner.
Materials and Methods: To address the research purposes, we used a cohort study in which a total of 2368 implants were placed on 1011 patient in the Clinic of Tehran University of Medical Sciences. The predictor variables included demographic variables, the health status and variables are related to implants. The outcome variable of interest was implant failure. The overall implant survival was estimated using the Kaplan-Meier analysis. First, risk factors were identified using Chi-square test and Fisher's exact test and then the Cox proportional hazard regression models were used for more analysis.
Results: The overall 39 month implant survival using the Kaplan-Meier function was 0.99±0.002. The implant location (jaws) (P=0.049) and type of teeth (P=0.011) were found to have significant relation with failure times in Cox proportional hazard model.
Conclusion: According to result of this study, both implant location and type of teeth had effection the failure times so that, the survival in mandible was higher than maxilla. The failure rate was higher in anterior teeth than that of others (molar, premolar, canine and primary).
 

Background and Aims: In modern societies, the incidence of oral cancer is increasing. It may be due to the increased population, life expectancy, and exposure to risk factors. This increase can particularly be seen in women and in our own country, Iran. The aim of the present study was to explore the status of care and treatment of patients with oral cancer referring to Shariati educational hospital in Tehran, during the years 2003-2013.
Materials and Methods: The present study was a cross-sectional descriptive survey on oral cancer patients attending the Shariati hospital in Tehran during a ten-year period. Data were collected through patient records and statistically analyzed by SPSS21 software.
Results: Regression analysis was performed in 5 models, where variables such as age, gender, location of the tumor, stage and grade was entered as independent variables and delay in treatment (time interval from diagnosis to treatment) entered as the dependent variable. The analysis showed that the elapsed time from diagnosis to treatment had a positive association with age of the patients. It means that the higher the age, the more delay in treatment (P<0.05). No relationship was found between the treatment delay and gender, tumor location, grade, and stage.
Conclusion: Considering the consequences of oral cancer for patients, there was necessity to formulate plans for preventing, early detection and improving quality of life in oral cancer patients.
 

Background and Aims: To create a good adhesion between porcelain veneers and zirconia restorations has been important issues is the prosthesis. The aim of this study was to identify an effective way to prepare the zirconia surface infrastructure to increase its shear bond strength to the porcelain veneer.
Materials and Methods: 75 samples of zirconia (Y-TZP) cylinders (diameter of 7 mm and a thickness of 3 mm) were fabricated. Based on the surface treatment, specimens were randomly divided into 3 groups: control, air abrasion and
Er-YAG laser. After surface treatment, the specimen surfaces were examined by SEM. Using a metal mold, the porcelain was veneered on the zirconia surface and then fired. After thermocycling, the shear bond strength of porcelain to zirconia was measured and then the failure mode of each specimen was analyzed using a stereo-microscope. Data were analyzed by one-way ANOVA and Tukey test.
Results: Significant differences were observed between the mean shear bond strength of different groups (P=0.001). The greatest amount of shear bond strength was observed in the group (S) and the lowest bond strength in the control group. Analysis of failure modes showed no statistically significant difference in the type of failure among study groups. The adhesive failure was predominating failure at the intersection of porcelain veneers.
Conclusion: The highest shear bond strength between zirconia and porcelain was achieved by sandblasting the zirconia surfaces compare with that of Er_YAG application.

Background and Aims: While there are a lot of information about an illness risk factors, there are still some gaps in understanding factors influencing the progression of disease. Given the important role of psychological factors in physical conditions, the purpose of this study was to compare the cognitive emotion regulation, stress, depression, anxiety, and stress related to life events in people with and without periodontal disease.
Materials and Methods: The type of this study was causal comparative. Research society was all clients referred to dental clinics in Lamerd and Mehr cities, then 50 people with and 50 people without periodontal disease (male and female, 15-49 years old) were selected using purposive sampling. The group without periodontal disease was matched with patient group in terms of demographic characteristics. Both groups completed cognitive emotion regulation questionnaire (CERQ), Depression Anxiety Stress Scale (DASS), and life events questionnaire. Data analysis was conducted with SPSS version 17 using multivariate analysis of variance (MANOVA).
Resultes: Data analysis showed that people with periodontal disease had more stress, depression, anxiety, and stress related to life events than matched control group. The groups had significant differences in the components of self-blame, rumination, positive attention to evaluation and catastrophizing (P<0.05). People with periodontal disease had higher scores in self-blame, rumination and catastrophizing and lower scores in positive attention to evaluating compared with matched control group.
Conclusion: The results showed people who were vulnerable to stressfull situations, depression, and anxiety during their lives, and also use maladaptive emotion regulation strategies, were more susceptible to periodontal disease.

Background and Aims: Microorganisms are the main cause of pulpal and periapical diseases. The most important failure factor is the lack of proper seals for the canal, resulting in microbial leakage. Therefore, the purpose of this study was to evaluate the sealing ability of ProRoot MTA and Bio MTA in canal obturation using fluid infiltration.
Materials and Methods: In this experimental study, 46 extracted mandibular premolar single canal teeth were used. After preparing and disinfecting the teeth with 3% sodium hypochlorite, their crowns were cut off from the cement-enamel junction. The teeth were then randomly divided into four groups: Group 1 (n=20) Bio MTA, Group 2 MTA ProRoot (n=20), negative and positive control groups, each of them contained 3 teeth. The preparation of teeth was performed using the step back method. The filled teeth were then evaluated by fluid filtration for leakage prevention. Data were analyzed by Mann-Whitney test and Tukey test (α=0.05).
Results: The results of statistical analysis showed that there was no significant difference between the MTA ProRoot and Bio MTA in sealing ability (P>0.05). That micro leakage is less in the Bio MTA group than in the ProRoot MTA group, but the difference was not significant.
Conclusion: This study showed that MTA ProRoot and Bio MTA can be used as appropriate canal filling materials.

Background and Aims:The erosive and ulcerative forms of Oral lichen planus causes pain and irritation, affects the nutrition and biological quality of the patient. Considering the high prevalence of the disease, the complications of conventional treatments and the resistance to classical drug therapy, the aim of this study was to compare the effect of infrared low level laser and triamcinolone acetonide mouth rinse on treatment of oral lichen planus lesions.
Materials and Methods:In this double blind clinical trial, 24 patients were selected randomly according to the inclusion and exclusion criteria and divided into two groups of 12. Before and after the study, pain and burning sensation index (VAS), apparent shape and score of the lesion and size of the lesion were recorded in the patients. We treated the first group with low level infrared laser (810 nm) twice a week with 0.5-2 j/cm² energy density and 300 mW/cm² power density up to a maximum of 10 sessions. For the second group, we prescribed a mouth rinse of triamcinolone acetonide 0.2% four times a day with antifungal drugs for a month. Then, the study`s criteria were recorded after the completion of treatment. All data were statistically analyzed using the repeated measure ANOVA test to compare the quantitative changes over time, The Mann-Whitney U test was used to compare the rank variables between two groups at any time and Friedman test for each group between different times.
Results: There was no significant difference between the groups in terms of severity of pain (P=0.255), score and size (P=0.186), and appearance (P=0.178) of the lesions among two groups. Although the two groups showed a significant decrease in all three indicators.
Conclusion:Considering that in both groups, all three indices were improved and these improvements were similar, it seems that laser therapy can be effective. It could be used as a therapeutic alternative in treating patients with OLP (Oral Lichen Planus) especially in cases with contraindication in corticosteroid administration or lack of appropriate therapeutic response or when there is resistance to treatment.

Background and Aims: Color is the most important and complicated part of aesthetic dentistry. The tooth color matching of restorations is considered as one of the most difficult tasks in the restorative dentistry. The aim of this study to evaluate the effect of two training methods on the dental students’ ability in determining tooth color matching.
Materials and Methods: In this study, 40 dentistry students participated which randomly allocated into two groups. The first group consisted of students who learned teeth color matching methods practically. In the second group, training booklet was used for learning. Using Vita Classic shade guide series, 4 color samples were chosen and the students of each group were asked to determine samples’ color, before, after and one month after the training.
Results: Booklet learning group was more successful in determining fourth color sample. However, in no studied group and no used samples, the results of one month after learning were not better than that of before learning. Also generally, no significant relationship was found between the color matching accuracy, using glasses, and sex of participants.
Conclusion: The use of booklet learning was more effective than practical learning in color matching accuracy for dental students. Also, using glasses and sex were not effective on their color matching accuracy.

Background and Aims: Management of an emergency is ultimately the dentist’s responsibility. Therefore, the dentists need to be able to manage an emergency and perform Cardiopulmonary Resuscitation (CPR) if necessary. The present study was undertaken to assess the knowledge of final-year dental students in Tehran regarding CPR.
Materials and Methods: In a cross-sectional study, 200 final-year dental students (44 males and 156 females) from 4 dental schools in Tehran were randomly selected and surveyed using a multiple choice questionnaire evaluating their knowledge about CPR. The data were analyzed by SPSS16 software using two descriptive and inferential statistical methods via chart drawing of statistical quantities calculation and analysis of variance.
Results: The mean score was 5.43±2.43. A positive correlation was found between receiving practical training and level of knowledge (P=0.001). However, the results showed no statistical differences between sex (P=0.409) or various dental schools (P=0.089).
Conclusion: Since, the level of knowledge about CPR among participants were poor, there is a perceived need for further training in dental schools.

Background and Aims: Reconstruction of osseous defects is one of the ideal goals of periodontal treatments and dental implant therapy. Different biomaterials have been used for this purpose and many studies have tried to compare and introduce the best ones. The present study aimed to evaluate the effect of PDFDB (Partially Demineralized Freeze-Dried Bone Graft) and FDBA (Freeze Dried Bone Allograft) on the regeneration of rabbit calvarial defects.
Materials and Methods: In this experimental study, 48 similar defects with the diameter of 8 mm were generated in the calvarium of 16 rabbits. Two defects were filled with FDBA and PDFDB, while the other one remained unfilled as the control group. All defects were covered by collagen membranes. 6 and 12 weeks after surgery, the histologic and histomorphometric tests were performed to evaluate the following variables: the rate of new bone formation and its type, the amount of residual grafting material, degree of inflammation and pattern of bone formation. Comparison of osteogenesis percentage and residual biomaterial was performed by repetitive variance analysis, whereas qualitative variables were compared by Friedman non-parametric test.
Results: Regarding bone formation percentage, there was no statistically significant difference between three different groups at 6-week (P=0.33) and also at 12-week time points (P=0.98). The amount of residual material in the PDFDB group was significantly lower than FDBA (P=0.04) in the 6-week samples. However, this difference was not significant in the 12-week samples (P=0.41). Bone quality showed statistically significant difference between graft containing groups and control group after 12 weeks (P=0.01). It means, all samples in FDBA and PDFDB groups displayed lamellar bone after 12 weeks while in control group, only woven bone or a combination of woven and lamellar bone was seen.
Conclusion: FDBA and PDFDB demonstrated similar regenerating effect in the rabbit calvarial bone defects and hastened bone maturation compared to the non-grafted defects.

Background and Aims: One of the most important challenges for dentists is providing a crown with appropriate marginal fit and gap. The 135-degree tooth preparation found to have some advantages such as technical ease and appropriate finish line record. Despite the advantages of 135-degree tooth preparation, scant research has been done in this area. Therefore, the aim of this study was to compare 135-degree and deep chamfer tooth preparation on the marginal fit and marginal gap of posterior metal-ceramic crowns.
Materials and Methods: Deep chamfer and 135-degree tooth preparation were performed on the two first mandibular molars with healthy coronal tissue and similar size. Impression was taken from each tooth and 30 crowns were made on each die. The sample plastered with fit checkers were pressed under the force of 40 N for 3 min in a universal testing machine. They were measured and recorded under a loop with 40x power in three points on each aspect. Data were analyzed by Wilcoxon and Kolmogorov-Smirnov tests using SPSS version 24.
Results: The mean marginal fit values in deep chamfer and 135-degree were 48.5417µm and 55.3333 µm, respectively with no statistically significant difference (P>0.05). While the mean marginal gap in deep chamfer (2.4833 µm) was significantly higher (P<0.05) than 135-degree (1.0083).
Conclusion: It can be concluded that the marginal gap by 135-degree’s tooth preparation was lower than that of deep chamfer in metal-ceramic crowns. However, no significant difference in the marginal fit between the deep chamfer and 135-degree tooth preparation was found.

Background and Aims: Dental caries is a multifactorial and common disease that leads to a decrease in the quality of life of individuals. The aim of this study was to determine the relationship between serum vitamin D and dental caries in the third year-to-last year students of dental school of Tehran University of Medical Sciences.
Materials and Methods: This descriptive cross-sectional study was conducted on 123 dental students. Demographic and health information were completed through a checklist. The level of vitamin D in individuals was measured by blood sampling. We recorded caries by ICDAS (international caries detection and assessment system) in two levels of D(1-6)MFT (total of decayed, filled and missing tooth) and D(3-6)MFT (total of progressive decayed, filled and missing tooth). Data analysis was done by the SPSS package version 25 using statistical tests of correlation and regression.
Results: The results showed that the correlation coefficient between vitamin D and caries index D(1-6)MFT was -0.89 with a P-value of 0.3328 which was not statistically significant. Based on the backward logistic regression, there was a positive significant statistical association between the D(3-6)MFT with vitamin D deficiency (P<0.001), weight (P=0.012), dental visit (P=0.023) and frequency of sweet snack consumption (P=0.03). In addition a significant and inverse statistical association was reported between the D(3-6)MFT and milk consumption (P=0.026).
Conclusion: Among dentistry students, no relation between vitamin D deficiency and early stages of decay was seen, however this relation was statistically significant in regard with progressive dental caries.

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.

Background and Aims: Restoration of non-carious cervical lesions (NCCLs) is challenging due to the difficulty of adhesion of dental tissues. The aim of this study was to investigate the effects of three methods of surface treatments using diamond bur, Er: YAG laser and sandblasting on the microtensile bond strength of resin composite to the noncarious dentin in cervical lesions.
Materials and Methods: In this in vitro study, 48 canine and premolar extracted human teeth with NCCLs at the buccal surface were selected and randomly divided into 4 groups of twelve each: control group without any treatment, Er: YAG laser group, diamond bur group and sandblasting group. For all groups, the bonding agent used was Clearfil SE Bond and then the cavities were filled with
the Filtek Z250 resin-composite. After this step, the teeth were cut and then subjected to the microtensile bond strength test. Data were analyzed by the Kruskal Wallis test.
Results: According to the obtained results, the microtensile bond strength, from the highest to the lowest values were in the sandblast group (24.57±10.24 MPa), the diamond bur group (19.19±10.8 MPa), laser group (18.59±9.05 MPa) and the control group (18.56±9.27 MPa), respectively. Although, no statistically significant difference was found between any of the groups (P=0.266).
Conclusion: It seems that in teeth with NCCLs, the sandblasting method had a much better effect on the bond strength, although no statistically difference between surface treatment methods was found.

Background and Aims: Different factors play a role in causing tooth decay. Modern dentistry is looking for a way to prevent tooth decay and suggests different ways to increase remineralization. The aim of this study was to evaluate the effect of nanohydroxyapatite toothpaste and mouthwash on remineralization of primary enamel lesions and obstruction of tubules.
Materials and Methods: In this study, 90 human extracted central teeth were used. Artificial decay was induced by placing the specimens for 72 hrs in a demineralization solution in an incubator at 37 °C. Hardness of the specimens was determined by a microhardness test before any surface treatment. The specimens were then divided randomly into 6 groups of 15. For 1-6 groups, the specimens were subjected to a pH cycling for 14 days, which included 3 hrs of demineralization and 21 hrs of remineralization. At the same time, 1-3 groups were in contact with diluted toothpaste in a ratio of 1:3 with deionized water at a rate of 5 ml twice a day for two min. Eac specimen of 4-6 groups was exposed to 5 ml of three types of mouthwashes for one min. Then, the specimens were cut in the buccolingual direction in order to simultaneously evaluate the dentinal tubules and Vickers microhardness test was performed again and the before and after microhardness values were compared. Then, the percentage of deposition on the surface and tubule obstruction were analyzed using SEM (Scanning electron microscope) (P=0.006). Data were analyzed using SPSS24 software bu the descriptive statistics, ANOVA analysis of variance, and multiple Tukey comparisons.
Results: The results of analysis of variance test showed that there was a statistically significant difference in the microhardness changes between study groups (P=0.006). Also, in-group analysis of microhardness changes, there was a significant difference (P<0.0001). Besides, only in the group containing 0.5% nanohydroxyapatite toothpaste, more than 50% tubule deposition and obstraction was observed (P<0.05).
Conclusion: According to the present study, nanohydroxyapatite can be one of the treatment strategies to repair incipient lesions of teeth and the addition of nanohydroxyapatite, preferably to toothpaste, increases the dental microhardness.

Background and Aims: Dental caries affects the quality of life of children and parents, oral health and overall health which can interfere with the childrens’ daily activities and growth. The purpose of this study was to investigate the relationship between the severity of dental caries and quality of life in pre-school children.
Materials and Methods: This cross-sectional descriptive study was conducted on 145 parents and preschool children aged 2-5 years old referring to Ahvaz dental school and a pediatric dentistry office in Ahvaz city. The convenient sampling method was used and participants were patients referred to the faculty of dentistry and one pediatric dentistry office in Ahvaz. Early Childhood Oral Health Impact Scale (ECOHIS) questionnaire was used to evaluate the oral health related quality of life. The demographic information and dmft index (decayed, missing, and filled teeth) was assessed for children. Statistical analyzes included descriptive statistics, Spearman and Pearson tests.
Results: The mean age of children was 4.12 ± 1.2 years. 72 children (49.65%) were boys and 73 of children (50.34%) were girls. Based on our results the mean ECOHIS score was 39.69 ± 18.95. There was a significant correlation between decreased quality of life and the lower age of the children (P=0.047), less parental education (P=0.018), more dmft score (P=0.000).
Conclusion: It can be concluded that severity of dental caries is effective on children's quality of life. The quality of life of children decreases with the increase in the dmft, lower socio-economic status of parents, and higher age of parents.

Background and Aims: Due to their professional nature, dentists and nurses are in close proximity with patients and the droplets of infected patients can increase the risk of cross-transmission and viral diseases, especially COVID-19. Therefore, the purpose of this study was to evaluate the level of anxiety and awareness of the final two-year nursing and dental students at Isfahan University of Medical Sciences regarding COVID-19.
Materials and Methods: This descriptive, analytical, and cross-sectional study examined all the students studying in the last two years of dentistry and nursing, Beck Anxiety Inventory and online awareness questionnaire available to students were placed. The variables of this research included year of study, major, anxiety, and awareness. After collecting data using chi-square test and frequency distribution tables, the results were analysed using SPSS software version 23 and at an error level of 0.05.
Results: 429 students participated in the study, most of them were nursing students (58.7%) and the highest frequency of students was from the entry year of 2018 (29.6%). The average anxiety of nursing students in 2017 entry was 31.12 at severe level and in 2018 entry was 28.53 at moderate level. The average anxiety of dental students in 2015 entry was 33.93 at severe level and in 2016 entry was 36.65 at severe level. Also, the level of knowledge of nursing students was higher than that of dental students in most of the examined questions about corona virus and a significant difference was observed between students (P<0.05).
Conclusion: The level of awareness of nursing students was higher than that of dental students, and the level of anxiety in dental students was high. Recognizing the limitations of this cross-sectional study, itcan be concluded that only a small number of dental students had good knowledge about  COVID-19. Students who had a higher year of education gave more correct answers. It is important to strengthen the knowledge about biosafety during the professional training of dental students in order to reduce the risks of contamination and cross-infection during patient care. It would be necessary to hold training courses to increase the level of awareness and to reduce students' anxiety.

Background and Aims: Posterior crossbite is a common malocclusion disorder in the primary dentition that affects masticatory function. Therefore, early detection and treatment of crossbite teeth is essential to prevent further dental complications and guarantee proper jaw development. This study investigated a reasonable and computationally efficient diagnostic system for detecting characteristics between children with and without unilateral posterior crossbite in the primary dentition using the surface electromyography (sEMG) activity of masticatory muscles.
Materials and Methods: The present study was an experimental in vitro study that used sEMG signals and support vector machine (SVM) to develop artificial intelligence systems capable of decoding muscle activity for diagnosing the crossbite. The core idea of SVM is to find the optimal separating hyperplane that maximizes the margin between two classes (presence or absence of crossbite disease) in the sEMG signal. In this study, 40 children (4  to 6 years old) were selected and divided into unilateral posterior crossbite (UPCB) (n=20) and normal occlusion (n=20) groups. The sEMG activity of the bilateral masticatory muscles was recorded during two 20-s gum-chewing sequences. Then, the time domain and frequency domain features had been obtained. In this study, eighteen time domain features and nine frequency domain features were employed. Finally, these features were used as inputs to the SVM method for data classification and crossbite disease diagnosis. In this paper, four kernel functions of SVM including linear, 2nd order polynomial, 3rd order polynomial and radial basis function were considered.
Results: Based on the obtained results, the crossbite disease had a significant effect on the EMG signals. The results demonstrated that this disease affected the amplitude of the signal more than the frequency. Therefore, using the time features of EMG signals, the SVM method was able to provide a more accurate prediction of crossbite disease. The findings indicated that the mean absolute value feature achieved a 95% accuracy in predicting posterior crossbite. Finally, the results revealed that the RBF method could exhibit superior performance.
Conclusion: The proposed method can be utilized in clinical applications for diagnoses of unilateral posterior crossbite. The findings of the study showed an influence of crossbite on the electrical activity of the temporal and masseter muscles. Therefore, the crossbite problem can be  reasonably diagnosed by an appropriate learning strategy using EMG signals.