Journal of Dental Medicine

Background and Aims: The aim of this study was to assess the outcome of short implants (<8 mm length) as an alternative to sinus lift surgery and placement of standard-length implants (10-12 mm length) for rehabilitation of atrophic posterior maxilla.
Materials and Methods: In this prospective clinical trial, 26 patients with 6-7 mm of residual alveolar bone height in their atrophic posterior maxilla were randomly divided into two groups (n=13). The test group received short implants without sinus lift surgery while the control group received standard-length implants after maxillary sinus floor augmentation. The bone loss was evaluated at 1 to 2 years after loading of implants on radiographies and the comparison between the two groups was done using chi-square test.
Results: At 1 year, two patients (15.4%) in the short implant and one patient (7.7%) in the standard implant group experienced bone loss (P=0.5). At 2 years, four patients (30.8%) in the short implant and two patients (15.4%) in the standard implant group showed bone loss (P=0.4).
Conclusion: At 2 years after loading, the bone loss was not significantly different around short and standard-length implants. Short implants appeared to be a suitable alternative to sinus lift surgery and placement of standard-length implants for rehabilitation of atrophic posterior maxilla. However, further studies with longer follow ups are still required to cast a final judgment in this respect.

Background and Aims: Passive fitness of implant frameworks are important factors for long-term success of dental implant restorations. The aim of this in vitro study was to evaluate the dimensional changes of implant supported zirconia frameworks fabricated by Zirkonzahn CAD/CAM system during fabrication stages.
Materials and Methods: The master model of 3-unit FDP was made of two implant abutments. The master model was scanned 12 times and data were saved as STL files (scanning groups). Using semi-sintered zirconia,
12 real-size frameworks (milling groups) and 12 enlarged frameworks which were then sintered (sintering group) were made in this system. Dimensions of master model and specimens of each stage were measured. The dimensional changes in respect to master model were calculated. Data were analyzed using Repeated measures ANOVA, independent t-test, and paired sample t-test at α=0.05 of significance.
Results: The milling stage showed greater dimensional changes comparing to the other stages (P<0.05). At all stages, the dimensional changes of premolar abutment height were greater than canine (P<0.001).
Conclusion: Within the limitations of this study, the results suggested that the fabrication stages and size of abutments had significant effects on the dimensional changes of zirconia frameworks.

Background and Aims: Today, resin composites are one of the most commonly used materials in restorative dentistry. However, failure in resin treatments is also common due to its chemical nature and its high talent for decay recurrence. According to conservative approaches, "conservative" treatments are more likely to be considered than "Replacement" of damaged remedies. The purpose of this study was to compare different surface preparation methods on composite surfaces to achieve the highest bond strength between the old and new composites after accelerated aging.
Materials and Methods: First, composite cylinders with a diameter of 6 and a height of 5 mm were prepared using an incremental technique and a microhybrid resin composite. The specimens were stored in distilled water for 6 months at 37°C and then the surfaces of all aged compsites were roughened using diamond milling followed by phosphoric acid etching. The specimens were randomly subjected into five groups. Group 1: GC Composite Primer. Group 2: Universal bonding containing silane (Kuraray). Group 3: Self etching adhesive (SE bond; Kuraray) Group 4: silane (Ivoclar Vivadent) + Second bottle of SE bond bonding system (Kuraray). Group 5: control group with no treatment. Then, 5 mm incremental of new composite (similar to the aged composite with different color) were placed on the surfaces of specimens, sectioned, and thermocycled for 3000 cycles for the microtensile bond strength evaluation. The specimens were evaluated using a stereomicroscope after failure. Data were analyzed by one-way ANOVA and Post Hoc Tukey test.
Results: The specimens in which silane and SE bond were used showed the highest mean microtensile bond strength and those treated by universal bond showed the least bond strength which were significantly different (P=0.02). All samples had cohesive failure patterns in all groups and the percentage of failures in old and new composites did not differ significantly (P=0.69).
Conclusion: : Based on the results, all surface preparations used in this study could provide an appropriate bond strength for repair of old composite restorations. Also, the microtensile bond strength between the old and new composites was higher than the cohesive strength of resin composite itself. However, the mean microtensile bond strength value for the group treated by universal bond was significantly lower than those treated by silane and hydrophobic containing bonding system.

Background and Aims: Use of computer and internet in our modern and digitalized society is an efficient tool to be up to date and fulfil the information gaps. The aim of this study was to evaluate the extent of computer and internet usage among dental students of Islamic Azad University, Tehran, in 2016.
Materials and Methods: This descriptive study for evaluating access and usage of computer and internet by dental students was done using a researcher-made questionnaire on 401 dental students. Validity and reliability (Kappa: 0.82) of the questionnaire was confirmed. Statistical analysis was done by SPSS22 using descriptive and Logistic regression analyses.
Results: More than 95% of the students had access to the computer and Internet. 45.6% of students reported their skills were in the basic level. The major use of computer among the students was internet but only 13.2% of students used Microsoft Office program. The students used the internet for dental subjects even monthly (34.9%) or weekly (29.4%). Only 9.7% of the students had participated in educational workshop for learning methods of research. The most limitation was internet velocity. Positive correlation was found among prospering ownership status (P<0.001), economic status (P=0.05), level of education semester (P=0.038) and the computer & internet usage (what’s more in terms of access and also in terms of improve information and knowledge).
Conclusion: Based on the results, a higher economic level, higher level of education, and property ownership made better access to the computer and Internet. However, computer skills should be more concerned in educational program.

Background and Aims: Gypsum products are used for several different purposes. Adaptation and success of casting restorations are dependent on dimensional accuracy, strength, and reproduction of details of dental gypsums. This study was designed to evaluate the dimensional changes and accurate details reproduction of three type IV dental gypsums.
Materials and Methods: 60 samples in 3 groups of dental gypsums of G30,Yeti Rock and FujirockEP were evaluated. The detail reproduction of 50 micron scratched line was analyzed by a microscope at 12× magnification. The samples were assayed for dimensional changes at 2 and 24 hours and 1 week after pouring. Photograph images were taken from samples in fixed distance by a camera (Canon D600) and analyzed in corel draw software. Data were analyzed using ANOVA and chi-square (P<0.05).
Results: There were significant differences in the details reproduction between three gypsums (P≤0.05) and the highest values was for Fujirock EP, Yeti Rock. The G30 did not reconstruct the details. There was no significant difference in the dimensional changes of the evaluated gypsums based on time (P≥0.05).
Conclusion: All three different gypsums evaluated in this study showed the dimensional stability during one week. Fujirock EP and Yeti Rock could reconstruct the details and G30 gypsum could not.

Background and Aims: Most children get a lot of anxiety while they visit a dentist. The most important factor in the child's fear at the beginning of treatment is the syringe and needle. Ways to cope with this anxiety include behavioural control techniques such as mental regeneration, distraction, and induction. The purpose of this study was to compare the pain and anxiety in children when using a syringe and toy- shape syringe needle. This study was the first study that used a toy-shape needle cover.
Materials and Methods: This clinical trial study was conducted on 20 children age from 5 to 8 years. More than half of them were anxious with Cfss-Ds (Dental Subscale of the Children's Fear Survey Schedule) and FIS
(Facial Image Scale) anxiety diagnostic tests, and the rest of them were not anxious. Patients were randomly divided into two groups. The first group received local anesthesia with conventional syringe and the second group, by syringe with toy shape needle cover. Following, the first group received local anesthesia by syringe with toy shape needle cover, and the second group, by a conventional syringe. Heart rate measuring and pain evaluating test was performed. Analysis of heart rate and anxiety data was performed by non-parametric wilcoxonsianed Ranks T-test (P-value was considered significant at 0.001).
Results: The mean amount of pain measured after using a syringe with a toy shape needle cover and using conventional syringe had a significant difference of 5.20% between the two groups. The pain was reduced in children who received local anesthesia by syringe with toy shape needle cover (P<0.001).
Conclusion: The physical appearance of the injection device plays an important role in reducing the anxiety and pain of injection in the children.

Background and Aims: Due to high mortality rate and cost of smoking, WHO has emphasized on the role of dentists in smoking cessation among patients. The aim of the present study was to investigate the dental students, knowledge toward health consequences of smoking, their attitude towards smoking cessation activities, and their education programs in this field.
Materials and Methods: In this cross-sectional study, the target group was senior dental students at Tehran and Shahid Beheshti Universities of Medical Sciences, and Azad and Shahed Universities. A questionnaire was used to collect data in addition to background information, on the knowledge, attitudes, and education towards tobacco cessation counseling in dental practice was administered to the students. The sampling method was census. Data were analyzed using oneway Anova followed by Turkey HSD post-hoc test for pairwise comparison.
Results: Overall 138 students participated in this program (The response rate was 100%). Of the maximum achievable knowledge score (28), the average knowledge score in Tehran University was 22.8, in Shahid Beheshti University 20.31, in Azad University 22.31, and in Shahed University 22.16 (P=0.027) with significant statistical differences. However, But the average of attitude and education score of the students did not vary significantly (P>0.05).
Conclusion: Most of the students had sufficient knowledge about the risks of tobacco use and positive attitude toward tobacco cessation counseling. It was concluded that the students would only pay attention to the principals of smoking cessation counselling when they actually believe in them. Therefore, in order to improve the performance of students, training should be given on tobacco cessation techniques at the dental schools, thus, that students could play an effective role in tobacco cessation counseling for patients.

Background and Aims: Today, smoking is recognized as a major health problem and an impediment to development in many developing countries. This is the reason of early deaths and disabilities which leads to death of about 4 million people around the globe annually. This study aimed at assessing the awareness and attitude among the students last years dental at Yazd Shahid Sadooghi Medical School in providing consultation for giving up smoking.
Materials and Methods: This study was a descriptive sectional study that evaluated the awareness and attitudes of students last years dental at school of dentistry. Data was collected through standard questionnaires and were analyzed by T test and Pierson correlation coefficient in SPSS18 software.
Results: A total of 110 students participated in this study. Awareness mean's score of female students was 18.38 and male students 17.66. The attitude mean's score of female students was 31.06 and the male students was 32.45. Based on the correlation coefficient of awareness with age (0.112), with the semester (-0.001) and with a GPA (0.76), it was concluded that awareness with increasing age and GPA increased, and with increasing semester decreases. Also, based on the correlation coefficient of attitude with age (0.013), with the academic semester (0.018) and with a GPA (0.008), it was concluded that attitude with increasing age, semester, and GPA was improved.
Conclusion: Despite the relatively good attitude of dental students about smoking cessation counseling, their awareness was poor. Therefore, the need to revise the education programs and steps in the field of training are required.

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.

Management of internal root resorption is a challenge to the endodontists. If it is left untreated, it may lead to the destruction of the surrounding dental hard tissues. Despite, routine obturation techniques are often employed without considering the best technique to solve this problem. This study presented a case of internal root resorption and apical periodontitis affecting tooth 12 (FDI) in a 31-year-old female patient, with a history of crown preparation in that region. We managed it with EndosealMTA and gutta-percha. After 12 months follow up, the tooth was still symptomless and in function and healing of bone resorption occurred.

Background and aims: Solubility is an important property of luting cements in determining clinical durability. The aim of this study was to compare the solubility of Panavia, Calibra and Maxcem resin cements with that of GC Fuji PLUS resin modified glass ionomer cement in three different pH values.
Materials and Methods: A total of 96 specimens were prepared (8mm diameter, 4mm thickness) according to manufacturer instructions. After setting, they were desiccated and weighed. The specimens were kept immersed in distilled water and lactic acid solution (pH values of 3 and 5) for 30 days and then removed and weighed again. Data were statistically analyzed by SPSS18 using two-way ANOVA with P≤0.05 set as the level of significance.
Results: The results of this study showed no significant difference between three pH values (P=0.08). The Calibra resin cement had the lowest value of solubility in distilled water and both pH of lactic acid. GC Fuji PLUS resin modified glass ionomer cement had the highest value of solubility in lactic acid and the Maxcem resin cement had the highest value of solubility in water.
Conclusion: The solubility characteristics of resin modified glass ionomer and three different resin cements were significantly affected by their composition and the storage condition.

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: Nasal obstruction is a common condition among children, in which delaying treatment can stabilize its negative effects on dentoalveolar structures during adulthood. In this study we aimed to investigate the effect of total nasal obstruction on the craniofacial structures of rabbits.
Materials and Methods: In this animal study, total numbers of 44 rabbits with high genetic proximity were selected. Several metal implants were inserted in the anatomic landmarks of their skulls and then underwent three different types of x-ray exposure (lateral, posterior-anterior and occlusal views). Half of them underwent surgically assisted total nasal obstruction, and the other half were considered as control group. All rabbits were kept in the same environment up to maturation period. Then, they underwent the same x-ray exposures. The primary and final radiographs were traced and various linear and angular were compared between them.
Results: The anterior facial height (P=0.01), maxillary depth (P=0.005), articular angle (P=0.005), maxillary and mandibular plan angle were significantly more in the rabbits with total nasal obstruction. However, the interdental width (P=0.005), maxillary perimeter (P=0.005), nasopharyngeal width (P=0.01) and maxillary and mandibular width were significantly less in them. The skull base length (P=0.30), gonial angle (P=0.40), and maxillary length (P=0.10) were not significantly different between the two groups.
Conclusion: Total nasal obstruction had various impacts on the craniofacial structures.

Background and Aims: All metal components of orthodontic appliances are somewhat corroded in the oral environment due to some changes in chemical, mechanical, thermal, microbiological and enzymatic factors which facilitates ion release. Ionic release can result in a discoloration of the surrounding soft tissue or allergic reactions in sensitive patients or even local pain in the area. In general, ions can cause toxic and biological side effects if their values reach the threshold, so the release of ions from the metal components of orthodontic appliances is important to us. The aim of this review article to determine the rate of orthodontic appliances ion release in different solutions.
Materials and Methods: A review of the literature was carried out in Pubmed, Google Scholare and Web of science database using selected key words (Saliva/ Titanium/Normal Saline/ Ion release Orthodontic appliance/Mouth wash/ Nickel/ Chromium). These searches were limited to the articles published from 2005 to 2018. According to the inclusion and exclusion criteria, 25 articles were obtained.
Results: Because of conflicts in the reported results, it was necessary to synchronize the measurement methods and also to use artificial saliva medium with normal pH as a control to achieve better systematic comparison.
Conclusion: There was significant differences in the ion release between mouthwashes. In all studies, the effect of pH and acidity has been shown to increase the release of these ions. In addition, stainless steel (SS) instruments had the least biocompatibility among all types of alloys evaluated.

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

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

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

Background and Aims: 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: 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.