Journal of Dental Medicine

Background and Aims: Microhardness, sorption, and solubility are useful predictors of a resin composite’s clinical success. This study aimed to evaluate the effect of 60 days of water storage on the microhardness, sorption, and solubility of 3 commercial nanohybrid resin composites.
Materials and Methods: Three nanohybrid composites were evaluated: GC Kalore (GC), Aura (SDI), and G-ænial Universal Flo Universal Flo (GC). Ten disc-shaped samples were prepared for each material. After baseline weight measurement, the specimens were stored in distilled water for a period of 60 days, and then in desiccators for another 60 days. Specimens were weighed at 24 hours, 7 and 60 days of water storage and desiccation. For the microhardness test, 24 were prepared for each material and divided into 6 groups based on storage media (dry and wet) and storage time (24 hours, 7 days, and 60 days). Specimens were tested by a digital Vickers microhardness tester after storage and data were analyzed using SPSS software.
Results: G-ænial Universal Flo Universal Flo showed the highest sorption and solubility and the lowest microhardness after 60 days of water storage. GC Kalore showed lower sorption and solubility compared to Aura. Also GC Kalore had higher microhardness than Aura after 60 days of storage in water, while Aura had higher microhardness in dry storage.
Conclusion: Composites with lower sorption and solubility showed higher microhardnss in wet conditions. Flowable composite resin showed the lowest microhardness and the highest sorption and solubility values. Therefore, the negative effect of water sorption and solubility on Surface microhardness should be considered in clinical decisions.

Background and Aims: Marginal gap measurement in all ceramic restorations they are of fundamental important for the successful used. As some studies led to contradiction results, yhe aim of this study is to compare marginal gap restorations between 4 kinds of ceramic restorations Inceram, IPS-e.max Press, Zirconia (CAD/CAM) and PFM.
Materials and Methods: In this In-vitro experimental research, one stainless steel die with deep chamfer finish line design (1 mm depth) was prepared on a maxillary premolar. 40 epoxy resin dies were made, dies were divided in to 4 groups (n=10), Zirconia, IPS e.max press, Inceram, Mental Ceramic systems (MC). Then, the prepared crowns were put on the stainless steel die and observed their marginal mismatch under sterio microscope before cementation. Data were analyzed by One- way ANOVA, and one sample kolmogorosmirnov tests.
Resultes: There was significant difference in the marginal gaps between (MC) (102.92±28.7), Inceram (98.41±24.91), IPS e.max press (128.22±25.48), and Zirconia (69.5±10.9) (P=0.0001).
Conclusion: The comparison of marginal gap for the four groups was significant test. Therefore, it can be concluded that marginal gap, the probability of leakage and recurrence of caries in Zirconia systems is the least and in the IPS e.max press systems is the most.

Background and Aims: A suitable restorative material must have acceptable mechanical properties. The aim of this study was to evaluate the effect of conventional acidic drinks on the micro-hardness of two dental resins.
Materials and Methods: 48 samples of each of P60 and G-aenial composites were prepared and randomly divided into six groups: Coca-Cola, Fanta, yoghurt drinks, soft beer, Sprites and control groups. The study was in 3 steps: after one day in distilled water and after one day and one week of immersion in beverages per day
(6 hours). The Vickers micro-hardness was then evaluated. Finally, data were analyzed by, t-tests, ANOVA and Tukey tests.
Resultes: Comparing the results between the two groups, a significant difference between the two composite was found. After one day in the water, the average micro-hardness for P60 was of 27.12 (kgf/mm²) and 16.51 (kgf/mm²) for G-aenial amount and these differences were found statistically significant (P=0.0001). For the
6-hour maintenance interval, the average micro-hardness between P60 and G-aenial was statistically significant (P=0.0001). For 42 hours, the average micro-hardness ranged between P60 and G-aenial that were statistically significant (P=0.0004). The stiffness of the P60 composite after 42 hours’ storage in soft beer significantly decreased compared with the control group (P=0.03). G-aenial composite hardness after 42 hours of soaking in the Coca-Cola was reduced significantly compared to yogurt drinks (P=0.02).
Conclusion: As a result, the hardness of P60 composite was higher than that of G-aenial. The hardness of both composites reduced in acidic drinks after one week.

Background and Aims: For the clinical success of implant-retained prostheses, fitness of matching components and stability of the applied torque to the implant-abutment assembly under dynamic occlusal loading is essential. The aim of this study was to evaluate the torque loss in Co-Cr castable abutments after cyclic loading.
Materials and Methods: 10 castable abutments were cast in Co-Cr alloy with similar size and height. Each specimen was mounted vertically on a separated implant using a 30 Ncm tightening torque. The detorque values of the abutments were evaluated after 10 min. The same tightening torque was applied to the abutments on their corresponding implants and cyclic loading was applied for 500,000 cycles to the implant-abutment assembly. The torque values after cyclic loading were recorded for each specimen. T-test analysis was conducted on scores from the groups.
Resultes: The results of this study showed that the percentage of torque loss in castable abutments was significantly increased after cyclic loading (P<0.001).
Conclusion: Misfit between the castable implant components can cause torque loss before and after cyclic loading. However, it is more appropriate to relate the results of this study to the screw loosening of the above mentioned abutments than judging their clinical performance.

FTIR spectroscopic imaging is a chemical imaging method that can be employed to a broad range of applications. This powerful technique is suitable for determining the functional groups and chemical structures of the samples. The advantage of infra-red spectroscopy is that it can be used for various modes of physical samples. The aim of the current paper was to review the recent advances and the potential uses of Fourier Transform Infra-red Spectroscopy in dentistry via exploring related literature during 1960 till 2017 in Science Direct and PubMed databases. One of the most popular applications of infrared spectroscopy is to calculate the degree of conversion in the resin based dental materials. It has also been used to investigate the chemical structure of the teeth and bones, synthesis calcium phosphate, the diagnosis of microorganisms, and pathological conditions. In this paper, we mentioned the principles of this technique and recommend this method as a simple and fast way to determine the structure of the materials and their alteration.

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: Loss of retention is one of the main reasons of failure in teeth restored with post and core. Several factors, including the type of cement can influence the retention of the posts. As zinc phosphate cement is considered as the standard for comparison this study performed to review articles evaluating the retention of cast posts cemented with zinc phosphate.
Materials and Methods: This systematic review was performed based on the PRISMA (Transparent Reporting of Systematic Reviews and Meta-analyses) guide. The question of this study was that how much is the amount of retention of cast posts cemented with zinc phosphate. Hence, a literature search was done in PubMed and Medline databases as well as Google scholar search engine using relevant keywords until 2016 limited to the English language. Articles were selected based on the inclusion and exclusion criteria, and were evaluated qualitatively.
Resultes: Internet search resulted in 1141 articles. Following the application of inclusion and exclusion criteria, 6 studies were included in this systematic review. The most common post material was nickel-chromium alloy. Retention of casting posts cemented by zinc phosphate was from 8.76 to 34.2 Kg and from 91 to 192.2 N.
Conclusion: Our review showed that the retention of cast posts cemented with zinc phosphate in controlled condition is moderate and factors including post material and length could influence the retention of the post.

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: In 1978 WHO (World health organization) formulated a histopathological definition for diagnosis of OLP (oral lichen planus). Previous studies showed that diagnosis of OLP with these criteria are not reproducible. In 2003 Van der Meij et al. represented new clinical and histopathologic definition for diagnosis of OLP known as modified WHO criteria. The purpose of this study was to evaluate the interobserver and intraobserver variability in the histopathological assessment of OLP based on the modified WHO criteria.
Materials and Methods: Fifty five microscopic slides which OLP and OLL (Oral Lichenoid Lesion) were recognized in their clinical differential diagnosis were given to 6 pathologists in two phases with 3 months interval. Each reviewing pathologist was asked to apply the modified WHO definition of OLP and to categorize each case as either OLP, or compatible with OLP. Then, the interobserver and intraobserver variability were assessed by calculation of repeatability coefficient and Kappa statistics.
Results: The results of this study demonstrated that interobserver variability based on modified WHO criteria was 0.77 (strong), while the intraobserver variability varied from 0.58 (moderate) to 0.82 (strong).
Conclusion: In the present study, the interobserver and intraobserver variability in the histopathologic assessment of OLP based on modified WHO criteria was stronger than previous studies which assessed WHO criteria. However, in order to propose the replacement of WHO criteria with modified WHO criteria, further studies with more cases and comparing the two methods is required.

Background and Aims: Fracture and color change are among the most common causes of clinical failure of resin composite restorations. Therefore, this study aimed to examine the fracture toughness and color changes of 3 Nano-hybrid resin composites in dry and wet conditions.
Materials and Methods: Three resin composites were studied. A total of 36 rectangular specimens were prepared for each material, randomly divided into 2 groups, and stored at 37°C dry or soaked in distilled water. In each group, the specimens were subdivided into three groups (n=6) and stored for 1, 7, and 60 days. After each time interval, the specimens were tested for the fracture toughness and loaded at a cross-head speed of 0.5mm/min using a universal testing machine. The baseline and final color measurement was recorded for each specimen using a spectrophotometer. The collected data was analyzed using ANOVA and Kruskal-Wallis tests.
Results: After 60 days, the mean value of fracture toughness was lower in the wet condition compared to that of dry condition. However, it was not significantly different except for aura Bulkfil (P=0.001). Color change was significantly different for Tetric Evoceram and aura with a greater value in the wet condition compared to that of dry (P=0.004). The greatest color stability was found for aura and the least for Tetric Evoceram.
Conclusion: In this study, most of the materials stored in a dry condition showed a greater fracture toughness and color change.

Background and Aims: Functional therapy locates the mandible in a more anterior and inferior position. Tongue posture and oropharynx space have a considerable relationship with mandibular posture. The aim of the present study was to determine the changes of tongue posture and oropharynx space following treatment with Twin block appliance in adolescent patients with class II division 1 ma1occlusion.
Materials and Methods: Twenty two patients (14 girls mean age:11.5, 8 boys mean age:12.5 years) who were treated with twin-block appliance were enrolled. Cephalograms were used to assess the linear measurements. Graber pattern and McNamara parameter were used to evaluate the tongue posture and oropharynx space, respectively. Data analysis was performed by paired t-test.
Results: The findings of the present study showed a significant increase in anterior position of tongue (P=0.06). Oropharynx space was increased significantly (P<0.001). There was a significant correlation between the decrease of ANB and anteroposterior increase of oropharynx space.
Conclusion: Twin-block appliance caused considerable forward movement of tongue and significant increase of oropharynx space in the sagittal plan.

Background and Aims: Wear resistance of artificial teeth has an important role in denture longevity. The purpose of this in vitro study was to evaluate the wear resistance of three types of composite resin denture teeth with that of acrylic resin.
Materials and Methods: In this study, four types of artificial teeth, including 3 types of composite artificial teeth (Ivoclar, Apple and Yamahachita) and 1 type of acrylic resin artificial teeth (Ivoclar) were used. Ten maxillary first premolars were selected from each set and were fixed in autopolymerising acrylic resin. The wear test was performed for 1000 and 2000 cycles. The heights and weights were measured under a light stereo microscope and scales (0.001 gram accuracy) before and after wear cycles. Data were analysed by ANOVA and Duncan tests (P=0.05).
Results: There was no significant difference between the mean wear of the composite and acrylic resin ivoclar artificial teeth in 1000 and 2000 cycles (P>0.05), but this difference was significant between the other artificial teeth (P<0.05). In 1000 and 2000 cycles, there was a significant difference between the mean weight loss of samples of all four artificial teeth groups (P<0.05). Also, in this study, the composite and acrylic ivoclar artificial teeth showed significantly less wear-resistant than that of other teeth, and the highest wear rate was found for Yamahachita's composite artificial teeth.
Conclusion: The findings of this study suggested that Ivoclar composite or acrylic resin denture teeth can be more suitable options than other artificial teeth used in this study in cases susceptible to abrasion.

Background and Aims: The dentistry profession is one of the most injuring professions that causes most pains and hurts for dentists because of their lack of knowledge about the ergonomic position through the work. The purpose of this study was to assess the ergonomic position of dentists with RULA method in dentists of Bojnord.
Materials and Methods: In this cross-sectional study, all of the Bojnord’s county dentists were selected. RULA method and Nowerdik questionnaire were used for investigating the agronomical position, and muscular-skeleton position, respectively. The analysis was done by SPSS22 using regression and chi-square test. A P-value of less than 0.005 was assumed as significant.
Results: The most muscle-skeleton reports were 55.6% (35 persons) related to back, 54% (34 persons) related to shoulders, 50.8% (32 persons) related to waist, and 47.6% (30 persons) related to neck aches. In the last 12 months, 90.5% of dentists reported pains from at least one of organs of their bodies and 27% were supposed to leave their works which the sex (P=0.84), length (P=0.75), and weight (P=0.38) were not significantly related to this case.
Conclusion: According to the results of this study educational interventions is essential to prevent the musculoskeletal disorders in dentistry.

Background and Aims: Despite their ascribed intellectual ability and achieved academic pursuits, the dental student’s academic achievement is influenced by learning motivation. This study in an Endeavour aimed to examine the learning motivation factors of dental students of Rafsanjan University of Medical Sciences.
Materials and Methods: In this descriptive-cross sectional study, 120 dental students completed the questionnaire which comprised of 33 questions regarding intrinsic and exogenic motivational factors. Demographic factors (gender, marital and native status, employment year of study) were examined. Data were analyzed by SPSS17 software. Descriptive and analytical statistical methods (t-test, Pearson correlation and ANOVA statistical tests) were used.
Results: The mean of the achieved scores in the domains of learning motivation was 2.98±0.32 out of 5,which was considered as moderate level. Comparing the means of the intrinsic (3.16±0.48) and exogenic
(2.82±0.44) domains showed significant differences (P<0.05). Correlation between the intrinsic motivation domain and elements of exogenic motivation domain with academic achievement were not significant (P=0.62). Total score of Intrinsic and exogenic motivation is higher in male and non-native students.
Conclusion: Educational motivation of Rafsanjan dental students was moderate. In learning, intrinsic motivational factor was more than exogenic factors in male students.

In recent years, the use of zirconia as a high-strength support for all-ceramic restorations has become widely accepted. The failure of zirconia restorations is mainly due to the weakness of veneering porcelain and other factors such as veneering approach. Except conventional hand layering, other methods such as pressing and digital veneering have been recently introduced and used. Meanwhile, the use of monolithic zirconia with no veneer is also a solution for reducing the rate of failure. The object of this review was to compare the failure of three available methods for veneering zirconia restorations in the literature and to compare with the monolithic zirconia. In the context of this overview, 42 articles were used between the years 2000 through the end of 2016 using the keywords of PubMed, google scholar search engines. In most articles, digital approach is the best way with low failure. mechanical properties of monolithic zirconia are reported to be higher than the zirconia veneered using hand layering method.

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: Increased tooth sensitivity is a common dental problem. One of the mechanisms of dentin hypersensitivity treatment is blocking dentinal tubules. The aim of this study was to compare the average closing dentinal tubules affected by carbonated Nano-hydroxyapatite and fluoride toothpaste using scanning electron microscope (SEM).
Materials and Methods: The enamel of gingival buccal crown surfaces of 42 sound maxillary premolars teeth were removed until the dentin surfaces were exposed. The dentine specimens of 3×3 mm were prepared. The specimens were washed by distilled water after etching and randomly divided into 6 groups. 3 groups were interfered with the carbonated nano-hydroxyapatite toothpaste and the other three groups interfered with Colgate toothpaste in 3, 7 and 14 days. The samples were examined by SEM to check the status of dentinal tubules. Then, they were evaluated by two researchers according to the Hulsmann index. Data were analyzed by using SPSS23 software and Kruskal-Wallis statistical test. The significance level of 0.05 was considered.
Results: The amount of dentinal tubules closure by the two toothpastes was significantly different. This difference was higher in the hydroxyapatite toothpaste than fluoride which were (P=0.024, 0.004 and 0.000), respectively. There were no significant differences among the groups in 3,7 and 14 days (P=0.230, 0.069, 0.537).
Conclusion: The toothpaste containing carbonated nano structural hydroxyapatite was more successful in closing dentinal tubules than Colgate toothpaste in short period of time.

Background and Aims: Cancer is the 3rd cause of death after heart disease and injuries in Iran. Radiotherapy and chemotherapy are the most effective procedures in cancer therapy, but their side effects are still unknown for many patients. The main goal of this study was to evaluate the patients’ knowledge with head and neck cancer regarding the complications of radiotherapy and chemotherapy.
Materials and Methods: This descriptive-analytical research was based on the information extracted from personal questionnaires and files of cancer patients who referred to the centers of Kerman University of Medical Sciences during a 6 months period in 2017. The data were analyzed by chi-square test at the significance level of 0.05.
Results: Our findings showed that most of the patients (76.48%) had low information level. There was no statistically significant association between the knowledge with demographic variables (P>0.05). However, patients with chronic disease had higher level of information. Only 10% of patients had received information by their physicians.
Conclusion: It seems there is not effective education regarding the rated radiotherapy and chemotherapy complications, because their knowledge was not in acceptable level. Considering the importance of this issue, it is necessary to perform educational program to improve patients' ability and skills to cope whit the chemotherapy and radiotherapy complications and their side effects.

Background and Aims: Children’s Fear Survey Schedule- Dental Subscale (CFSS-DS) is considered as the most popular instrument available to assess dental fear in children. The aim of this study was to develop a Persian version of the CFSS-DS among 8-12 year-old female children resident in Tehran.
Materials and Methods: At first, the questionnaire was translated in Farsi and  back translated in English afterwards. While, the back translated version was confirmed, we considered the Persian version as the final instrument. Content validity and reliability of the questionnaire was assessed. We used test-retest method to evaluate the reliability, 287 female students aged 8 to 12 from 7 schools in 6^th district of education ministry of Tehran were interviewed two times with interval of seven days. In addition, the infraclass correlation coefficient (ICC) and percentage of agreement were calculated. The score of dental fear was measured with range of 13 to 65 and changed to a number between 0 and 100. The relationship between dental fear score and the independent variables including age, history of hospitalization, last medical visit, and history of dental treatment were evaluated using the linear regression models.
Results: The mean score of dental fear was calculated 20.52. The score of dental fear was significantly associated with the last medical visit (P=0.04) and past dental history (P<0.001). The percentage of agreement was more than 80% for all the questions. In each question, Kappa was evaluated as moderate to good and ICC was good to very good (more than 0.4).
Conclusion: The findings of this study demonstrated that the Persian version of CFSS-DS was valid and reliable among 8-12 year-old children.