Journal of Dental Medicine

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: 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: 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: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: Making dental prostheses is sensitive and accurate work and requires powerful and skilled hands. Because of this, the dental prosthesis technicians may suffer harmful effects such as stress and fatigue during the course. The aim of this study was to investigate fatigue, stress and job performance and their relationship with some demographic variables in this community.
Materials and Methods: The present study was cross-sectional and done in 2016. The study population was a group of dental prosthesis technicians that had participated in a national congress in Tehran. Sampling was done by census Two standardized questionnaires on the subjects of fatigue and stress which were distributed among 100 female and male participants and sampling was done by census. Then, the obtained data was analyzed using SPSS16 software and applying descriptive statistics, Pearson correlation test, and ANOVA, T-test.
Results: From the 100 samples, there were 16 females and 84 males with mean age 34.71±7.90 and average work experience of 10.82± 9.01 years. 82 percent of the subjects were married and 42 percent of them were smokers. The results showed that 100 percent of dental prostheses technicians were facing with moderate to severe stresses. The stress and fatigue scores in married ones were higher than the single ones. The results showed a significant relationship between smoking, stress, and fatigue scores (P<0.05).
Conclusion: According to the high level of job stress in the dental prostheses technicians, this problem must be considered, minimized, and more attention should be paid to their psychological and emotional problems.

Background and Aims: In recent years, the dentistry workflow has developed considerably. By the introduction of computers and their various applications, the effectiveness and efficiency of treatment has increased enormously. Considering engineering concepts in the workflow, it is necessary for participants to assess different steps and data transferring between various software and hardware devices. This research investigated the interaction between dentists, laboratories and production centers through the required steps for accomplishing treatment by different applications of software and digital hardware devices.
Materials and Methods: Review in this article was based on searching Google scholar database considering key words: digital dentistry, workflow, computer aided design and manufacturing, dental CAD/CAM. This search was limited to the English articles published after the year 2000.

Conclusion: It is necessary in dentistry to use digital technologies to improve the efficiency of treatments. Thus, the participants in this field must have appropriate knowledge to choose and apply these tools. Moreover, the participant should help providers of digital solutions for better development of software packages and related hardwares.a

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: Despite the increasing application of intra-oral scanners, the effect of finish line position on gingival margins adaptation is still discussed. The purpose of this clinical study was to evaluate the fitness of cobalt-chromium copings obtained from intraoral scanning in two depth of finish lines.
Materials and Methods: Thirty teeth prepared for single premolar metal-ceramic crowns were included. Fifteen teeth had supragingival and fifteen had sub-gingival finish lines. Digital impressions were made using an intraoral scanner (Trios-3shape). Computer-aided design and computer-aided manufacture (CAD/CAM) cobalt-chromium copings were fabricated from the scan files. The copings were evaluated intraorally and after adjustments, the internal and marginal discrepancy were measured using silicone replicas and a stereomicroscopy. Internal and marginal discrepancies were analyzed using the Multivariate test (P<0.05).
Results: The mean internal and marginal gap were 52.1 and 56.27μ, for supragingival group and 49.72 and 62.98μ for subgingival group, respectively. The evaluation of finish line position showed no significant effect on obtained results (P>0.05).
Conclusion: CAD/CAM chrome-cobalt copings fabricated by digital impressions provided acceptable marginal and internal precision. However, the finish line position had no significant effect on the internal and marginal adaptation.

Background and Aims: Methicillin-resistant Staphylococcus Aureus (MRSA) is an important infection source in dentistry for different disinfectants to be used to prevent its transmission. Furthermore, a variety of chemical disinfectants are developed to remove bacterial infections from the dental care workers' hands and claims are made regarding their superiority in infection control, although all requires scientific investigations. The aim of present study was to compare the effects of chemical hand-disinfectants Micro Zed HD, Aseptoman and Decosept on MRSA (methicillin resistant staphylococcus aureus) in different periods of time.
Materials and Methods: In this experimental study, the antibacterial efficacy of three hand-disinfectants on standard strain of MRSA (USA300: ATCC® BAA-1717™) was evaluated according to European standard of evaluating antiseptics (EN 1040:2005 CSN EN). First we prepared a 0.5 Mc Farland (108 CFU/ml) suspension of MRSA, and exposed to three disinfectants for 15, 30, 60 and 90 seconds. Then, they were transferred to separate plates of Mueller-Hinton medium and incubated in 37^◦C for 24 hours. The plates were compared then with control plate to evaluate the efficacy of materials on bacteria by calculating the CFU/ml of plates.
Results: Three hand-disinfectants evaluated in this study had the maximum anticabterial effect on MRSA in the minimum time of exposure (15 seconds), and we found no trace of growth in any plates.
Conclusion: The three hand-disinfectans (MicroZed HD, Aseptoman and Decosept) in the concentration suggested by their companies, showed no difference in efficacy to remove MRSA from hands.

Background and Aims: Trauma to primary and permanent teeth caused post-traumatic complications affecting the health of teeth and led to specific problems in treatment. As prognosis of trauma has closed correlation with immediate and correct management after occurrence of the incident and the health educators are the first people in contact with children in this places, their awareness of how to deal with these injuries plays an important role in prevention and treatment. This study aimed to evaluate the knowledge of health educators in confrontation with dental injuries in primary schools of Sanandaj in 2018.
Materials and Methods: In this cross-sectional study, all of fifty-nine health teachers in primary schools of Sanandaj were identified after referring to education centre. The questionnaires were provided to the school health teachers after referring to schools and after completing questionnaires, collected data were analyzed. In order to test the research hypotheses, Multiple regression, Non-parametric tests of spearman correlation coefficient, Mann-Whitney and kruskal-wallis were utilized using SPSS software version 20.
Results: The mean knowledge score of fifty-nine health educators was 14.02±3.41 and knowledge score of females was higher. There was no significant statistical correlation between knowledge score, age,
work experience and education level (P>0.05). In this study, the knowledge score of experienced teachers in confrontation with injured persons and health educators who attended related training courses, was higher than others but this difference was not statistically significant (P>0.05).
Conclusion: The results indicated inadequate knowledge regarding emergency management of dental trauma. Thus strategies to improve the teachers’ knowledge about dental trauma can positively influence their knowledge and attitudes toward emergency management of dental trauma.

Background and Aims: One of the important fields of dentistry is surgery for dental implants. In this field, dentistry has developed considerably in recent years amongst other fields of medicine from the perspective of digital device and software application. Surgical guides help dental surgeon for more precise, confident, easier and shorter surgery. Process of producing these tools are full digital and to somehow complex due to the application of many technical devices, software and protocols. To achieve efficiency, all participants in the workflow must be aware of all steps and data requirements for production of guides. This paper investigates the production process of surgical guide comprehensively, and also, encompass all the steps in process with details.
Materials and Methods: This review article was based on searching Google scholar and PupMed databases considering key words: Surgical Guide, Guided surgery, digital dentistry, dental CAD/CAM, Additive manufacturing. More than 90% of the references were in English language and published after year 2010.
Conclusion: Today dentistry uses many digital solutions for dairy workflow and most of these solutions are developed by engineers in various fields of knowledge. Thus, this information is essential for dentists, surgeon, clinician and laboratory technician, etc. for better collaboration and participation. Amongst, advances in surgery of dental implant have been highly significant and patients benefit from better treatment and less inconvenience. In addition, dentists do surgery more precise and easier because of considering all conditions before of surgery. Thus, it is substantial inform of all steps of production process.

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: Despite patient’s demand increased for tooth color restorations, the stable bond between dentin and composite is a challenge in dentistry. Dentin protease activation is responsible for dentin-resin bond failure. The aim of this study was to determine the best pretreatment agent to inhibit matrix metalloproteinase and increase resin-dentin bond durability.
Materials and Methods: After collecting 24 intact third molars, the dentin surfaces were exposed immediately under DEJ. After acid etching of dentin rewetting was done with CHX 2%, EDC 0.3 M for 60 and water (control group). Then the adhesive (Single bond, 3M ESPE, USA) and composite (Filtek Z250 XT, 3M ESPE, USA) were applied. 48 sectioned dentinal specimens were prepared. The specimens were divided into 3 groups. Each group was divided into 2 sub groups (n=8). In half of each group, the micro tensile bond strength test was done immediately and another part half 6 months. Then, the specimens were evaluated by stereomicroscope and SEM. Statistical analysis was performed using SPSS23 software, two-way ANOVA and multiple Tukey and T-test comparisons. P<0.05 was considered as a significant level.
Results: There were not significant differences between immediate micro tensile bond strength of CHX, EDC and control groups (P=0.97). However, there was significant differences between CHX, EDC compared with the control group (P≤0.0001). Comparison between the immediate and 6-month bond strengths in each group, only in EDC group, there was no significant after 6 months’ difference (P=0.64).
Conclusion: EDC and CHX t did not have any effect on the immediate microtensile bond strength. After 6 months, EDC prevented bond strength deterioration, but the bond strength was decreased after CHX usage.

Background and Aims: Diferences whithin shape and size of hand wrenches in diferent systems could affect the torque applied. Therefore, evaluation of wrenches has been emphasized. The aim of the present study was to compare the torque values of the long and short torque wrenches in different implant systems including ITI, Implantium and Nobel Biocare.
Materials and Methods: In this experimental trial, 5 dentists with at least 5 years of professional experience closed the abutment screw in different implants systems using the long and short manual wrenches while the wrench-induced torque values were calculated by digital torque-meter. Torque application was done for 3 times with 10-minutes resting time between each wrench uses in the habitual closing torque manner. Data were analyzed using two-way analysis of variance test in different implant systems, while the paired comparisons were done using Tukey post hoc test.
Results: The maximum torque values of the long manual wrenches were 27.73±4.57 Ncm, 34.6±8.09 Ncm and 30.6±6.94 Ncm for the ITI, Implantium, and Nobel Biocare systems, respectively. While the values were reported to be 26.4±5.3 Ncm, 35.27±7.94 Ncm and 30.13±5.26 Ncm in the short manual wrenches for the ITI, Implantium and Nobel Biocare systems, respectively. Significant differences were found between ITI and Implantium (P<0.0001), and between Implantium and Nobel Biocare systems (P<0.021). However, no significant differences were observed between ITI and Nobel Biocare systems regarding wrench-induced torque values (P>0.05).
Conclusion: From the results, the torque values obtained by different long and short manual wrenches were specific to different implant systems. These values were less in ITI and Nobel Biocare systems and higher in implantun than those range provided for the implant systems by the companies.