Frontiers in Dentistry (FID)  is the first Iranian dental journal in English. FID is an Open Access, Peer-Reviewed  journal published by Dental Research Center (DRC) of Tehran University of Medical Sciences which is a dynamic, rapidly growing research center.

The Journal aims to publish novel and high quality relevant information written by peers to researchers and readers involved in all fields of dentistry, oral health sciences and related interdisciplinaries, strives to keep pace with the rapid growth of publications, and move on to the edge of knowledge in this field.

Frontiers in Dentistry encourages submission from General dentists, dental specialists, clinicians, students and postgraduate students of dentistry, as well as researchers and academic members who do research in the field of dentistry and oral health sciences. The journal supports the following types of articles:

  • Original/Research Article
  • Systematic Review/Meta-Analysis
  • Reports including Technical Reports and Case Reports
  • Letter to the Editor


Our Approach Towards COVID-19 Papers

Considering the importance of disseminating the most recent knowledge on COVID-19 during this ongoing pandemic, Frontiers in Dentistry is providing free fast track of all manuscripts related to the disease. Decisions on such papers shall be provided within a maximum of three weeks. 
We invite authors in different fields of Dentistry to submit their COVID-19-related manuscripts to this journal accompanied by a brief statement in their Cover Letter, explaining the importance of the study and what it would add to the existing literature. 
We also request that all colleagues who feel they can provide a timely review (maximum 2 weeks) on such papers, contact the journal at: and declare their availability. For each review completed within this timeframe Frontiers in Dentistry is offering a 20% discount on the next paper accepted by the reviewer, up until January 1st, 2022. Please note that points are collectable and a review of 5 papers by the same reviewer would result in a free article published in the journal, if accepted through peer review.
Mohammad-Sadegh Ahmad-Akhoundi, DDS, MSc.   Read more about Our Approach Towards COVID-19 Papers

Current Issue

Vol 19 (Continuously Published Article-Based)

Review Article

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    Root proximity is defined as a situation where the distance between the roots of adjacent teeth on radiographs is ≤1.0 mm. This important situation should be detected by clinicians before definitive restorative treatments and they should be well aware of different approaches available for the management of this situation. The purpose of this study was to collect and review the available literature on this topic by searching the PubMed, Google Scholar, Scopus, Embase, and Cochrane Library in order to summarize the complications and treatment plans for root proximity in cases requiring restorative procedures.

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    Objectives: Incorporation of fillers might improve the physical properties of sealants. This systematic review and meta-analysis evaluated the retention and caries development rate of filled and unfilled fissure sealants.

    Materials and Methods: This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. The PubMed, Scopus, Embase, Cochrane Database of Systematic Reviews, and ISI Web of Knowledge were searched until October 24, 2019. The risk of bias (ROB) was assessed for the included studies based on the Cochrane collaboration common scheme for bias, and the meta-analysis was performed through a random effects model.

    Results: The search resulted in 6,336 unrepeated relevant studies. After the title, abstract and full-text screening, 19 studies with 26 comparing groups were finally included in this systematic review and meta-analysis. According to the included studies, both retention rate and caries development in filled and unfilled resin-based sealants did not significantly differ within 2 years of follow-up.

    Conclusion: Since there was no significant difference in the retention rate and caries development between filled and unfilled sealants, it seems that the final decision should be made uniquely for each patient according to the type of fissure, patient’s age, habits, etc.

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    As the coronavirus disease-2019 pandemic outbreak continues to be a global public health concern, dentists should seek means to provide oral health care with minimal risk. To meet the recommendations of the Center for Disease Control, alternative non-aerosol generating techniques have been proposed to minimize the risk of disease transmission to patients and dental healthcare personnel. Among recent materials, silver diammine fluoride (SDF) has been shown to be effective in preventing and arresting caries. This along with an atraumatic restorative treatment with glass ionomer cements (GICs) makes it a potentially attractive adjunctive therapy for caries management in pediatric patients. In this technique, SDF is applied over carious tissue and the lesion is restored with auto-polymerizing GIC. This review article aims to provide a practical background and clinical guide for the application of silver-modified atraumatic restorative technique (SMART) as a safe way to provide dental services to children during the pandemic.

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    This integrative review aims to provide a consolidated evidence-based appraisal of the most up-to-date guidelines and recommendations of international public and professional health regulatory bodies in relation to preparedness framework for restructuring safe delivery of dental services amid and beyond the coronavirus disease-2019 (COVID-19) pandemic. Most recent updated guidelines for dental professionals from major international health regulatory bodies were reviewed. PubMed, Google Scholar, Cochrane Central Register of Controlled Trials, WHO COVID-19 and LILACS databases, along with relevant preprints were searched, and citations were checked up to January 23, 2021. The search was performed by one author. Shortlisted articles were read and brought to consensus to be included in the study by at least two co-authors. In case of any disagreement between the judgements, an independent co-author’s decision was taken as final. Of 849 records searched, 61 articles were included in the study. Following content analysis of the global guidelines and the collected prevailing evidence, the common themes and recommendations of different guidance documents were collated and summarized into seven domains. Most guidelines have a consensus regarding implementation of rigorous administrative, engineering and environmental infection control strategies. However, variations do exist with regard to the use of respirators in non-aerosol-generating procedure (non-AGP) settings, employment of airborne precautions during non-AGPs, use of supplemental air-handling systems, and preoperative use of mouthwashes. This evidence-based analysis can serve as a useful reopening resource tool and facilitate effective restructuring for delivery of optimal, equitable and safe dental practices globally, during and while emerging from the pandemic.

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    Oral biofilms are a group of healthy synergistic organisms, that on interplay with the immune system undergo transition and colonize the pathogenic bacteria, leading to various diseases like dental caries, gingivitis, periodontitis and a few systemic conditions. Dental caries being the most common disease of the oral cavity, comprise a heterogeneous group of bacteria that can cause imbalance in the biofilm. Caries prevention has been in research for decades, where antibiotics, chemical biocides and fluoride-antimicrobial approaches have not been adequate for this multifactorial disease. In recent years, the major focus of caries prevention has been shifted to plaque-biofilm modification as an ecological approach that would prevent bacterial colonization. Saliva produces various natural antimicrobial peptides that can regulate biofilm modification. Synthetic production of antimicrobial peptides concentrates on selective elimination and a targeted approach towards cariogenic pathogens, precisely Streptococcus mutans (S. mutans). A search in Medline/PubMed, EBSCO and ScienceDirect databases on C16G2, antimicrobial peptides (AMPs) and S. mutans, using MeSH (Medical Subject Heading) terms was performed and papers published until 2020 were included for further evaluation. A total of eight articles written in English with available full texts were selected based on the search strategy. They included four publications on AMPs against S. mutans and another four articles on AMPs in caries prevention. This review focuses on C16G2 antimicrobial peptide and its potential to modify biofilm and inhibit the targeted bacteria causing dental caries.

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    The coronavirus disease-2019 (COVID-19) pandemic due to the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has casted a deep impact on every aspect of the human life all over the world. The healthcare professionals dealing with the patients have been at the greatest risk of exposure. Dental practitioners fall among the highest risk practitioners because of their field of operation being around the oropharyngeal region of patients, as well as due to the risk of generation of aerosols during various dental procedures. There is a continuous urgent need of modifying the dental practice in accordance with the guidelines issued by the health authorities time to time. Meticulously planned approaches, and adequate precautions and modifications need to be introduced into dental practice. The field of orthodontics also demands a high level of practice modification in order to ensure proper infection control for patients, practitioners, and dental staff.

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    The main goals of treatment of dentofacial deformities are to achieve optimal esthetics and ideal functional occlusion. The conventional orthognathic surgical approach includes a long presurgical orthodontic phase, which takes about 18 months. During this phase, the patients’ appearance is deteriorated and their motivation to continue treatment significantly decreases. In the surgery first approach (SFA), orthognathic surgery is performed prior to orthodontic treatment, and orthodontic treatment is performed postoperatively to improve dental occlusion and for final settling. The SFA has two main advantages namely shortening of treatment period, and early improvement of the appearance of patient. The SFA has significant advantages especially for class III patients.

    This study aimed to review the available articles on this topic published from 2012 to 2019 to achieve a comprehensive understanding of different aspects of the SFA. The databases were searched by two researchers and a total of 11 eligible articles were selected for study inclusion. The results were categorized into two categories of stability of the results of the SFA, and duration of treatment, in comparison with the conventional approach.

    Although different aspects of the SFA have been previously evaluated by dental clinicians, a considerable gap of information still exists regarding the details of this approach, which calls for further research in this respect.

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    Teledentistry is a type of telemedicine and telehealth that aims to make all major specialties of the discipline easier through a remote approach to prevention and treatment of oral and dental issues. This new method enables distant access to individuals instead of direct, face-to-face, doctor-patient contact and has been made possible thanks to developments in information technology. Teledentistry was described in 1997 as “… the practice of using video-conferencing technologies to diagnose and provide advice about treatment over a distance”, and today it represents a modern way to practice dentistry by integrating digital imaging, electronics, health records, and telecommunications technology via an internet connection. This approach facilitates patients’ access to care in remote settings and also enables specialists at distant locations to arrive at a correct diagnosis as well as to propose proper therapy or refer patients, where warranted. The current brief report aims to describe the present and future of this modern approach in dentistry and its advantages in patient management from prevention to diagnosis to treatment.

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    Objectives: Endocrown restorations were introduced for endodontically treated teeth as a conservative treatment. However, data about the effect of preparation design on marginal integrity and fracture resistance of endocrowns are lacking. The purpose of this systematic review was to investigate the effect of preparation design of endocrown restorations on marginal integrity and fracture resistance.

    Materials and Methods: Based on PICO question and the search terms, PubMed, Embase, Scopus, and the Cochrane Library were searched. After including studies matched to predefined inclusion and exclusion criteria, the extracted data were tabulated in a table provided by the authors. Two reviewers assessed the methodological quality of each included study independently. Ten articles were selected for extracting the quantitative data. All included studies were in vitro. The potential risk of bias of the selected studies was assessed using the modified MINORS scale.

    Results: Four studies assessed the marginal adaptation, five studies evaluated the fracture resistance and just one investigated both the marginal integrity and fatigue resistance of the specimens. The evaluated influencing items in preparation design were as follows: cavity depth, occlusal thickness, ferrule effect, internal divergence angle, type of finish line, and adding vents inside pulp chamber. Meta-analysis could not be done due to heterogeneity of preparation designs and evaluation methods.

    Conclusion: Marginal discrepancy of endocrowns is intensified with adding preparation features, higher cavity depth and increasing the divergence. Fracture resistance of endocrowns is increased with more occlusal reduction and cavity depth. However, it is still beyond the normal clinical force range.

Original Article

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    Objectives: The basis of truth-telling is respecting the autonomy of patients and developing an ability to make informed decisions with valid consent. The purpose of this study was to ethically analyze the conflicts about truth-telling in dentistry.

    Materials and Methods: This case analysis focused on the issues of truth-telling in medicine and dentistry. The challenges encountered by dentists with respect to ethical issues related to truth-telling were discussed and analyzed by the research team.

    Results:  The literature review showed that the issue of truth-telling in dentistry has been addressed from three aspects: Truth-telling about other dentists’ medical errors, truth-telling about dangerous, refractory, or incurable diseases, and truth-telling to children or incompetent individuals for decision-making.

    Conclusion: When the duty of the dentist in truth-telling is conflicted with some other moral obligations, the conflict between the prima facie duties arises. The principle-based ethical theories provide a suitable conceptual framework for moral judgement in such conflicts. In cases of conflicts related to truth-telling, a balance should be maintained between principles and rules such as fidelity, respect for autonomy, maintaining trust in dentist-patient relation, and best interest of patients. The decision in truth-telling should be made individually for each patient based on the specific contextual conditions.

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    Objectives: The aim of this study was to evaluate the effects of rinsing water temperature and preheated composites on microleakage of class V restorations with two different bonding agents.

    Materials and Methods: Eighty class V cavities were prepared in the buccal and lingual surfaces of 40 molars. Single Bond and Prime and Bond NT bonding agents were used. The teeth were divided into four groups of 10. G1: After acid etching, cavities were rinsed with 23˚C water and filled with 23˚C composite resin. G2: Rinsing water and composite resin had 55˚C temperature. G3: Rinsing water had 55˚C and composite resin had 23˚C temperature. G4: Rinsing water had 23˚C and composite resin had 55˚C temperature. The specimens were immersed in 0.5% basic fuchsine dye. Microleakage scores were analysed with the Kruskal-Wallis, Mann-Whitney U, and Wilcoxon tests.

    Results: There were significant differences in microleakage of specimens prepared with Single Bond and Prime and Bond NT only in group 1 (P<0.05). There were no significant differences between the microleakage of groups rinsed with different water temperatures (P>0.05). There were significant differences between the unheated and preheated composite groups (P<0.05).

    Conclusion: Preheating of composite is a valuable method to increase its adaptability and decrease microleakage of composite restorations.

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    Objectives: For decades, the white coat has been the uniform of medical professionals. Recently, medical professionals show interest to use alternatives. We aimed to evaluate the perspectives and preferences of children and their parents regarding dentists’ attire and gender.

    Materials and Methods: This cross-sectional study was performed on 4-to 6-year-olds and their parents referred to dental clinics of Tehran School of Dentistry in 2018. Parents completed a questionnaire on demographics and dental fear, and both parents and children were asked about their preferences regarding the gender of dentist and the color of the dentist’s attire. Statistical analysis was performed by the logistic regression model.

    Results: Totally, 148 children (mean age of 5.42±0.71 years, 48% girls) and their parents participated in the study. Most of the participants (81.2% of the children and 68.0% of the parents) preferred colored coats compared with white coat. More than half of the parents preferred a female dentist for their children (56.5%) while most children preferred a male dentist (54.8%). Boys preferred a male dentist as well (P=0.01). The children were reluctant to go for a dental visit and preferred to be visited by a dentist of the same gender as themselves (P=0.041).

    Conclusion: Wearing colored coats by dentists and giving a chance to choose the gender of dentist in polyclinics may increase the children’s cooperation in pediatric settings.


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    Objectives: The purpose of this study was to evaluate the effect of saliva contamination on shear bond strength (SBS) of orthodontic brackets bonded by a self-adhering composite compared with a conventional adhesive.

    Materials and Methods: This in vitro, experimental study investigated 40 human premolars. The teeth were randomly divided into four groups based on the adhesive type and bonding condition: (I) Vertise Flow composite without saliva contamination (VF), (II) Vertise Flow composite with saliva contamination (VF/S), (III) Transbond XT composite without saliva contamination (TXT), and (IV) Transbond XT composite with saliva contamination (TXT/S). After the preparation step, brackets were bonded to the buccal surface of the teeth, and samples were mounted in acrylic blocks, incubated at 37°C for 24 hours, and underwent thermocycling between 5- 55°C. Next, the SBS was measured by a universal testing machine. Data were analyzed by ANOVA and Tukey’s test.  P<0.05 was considered statistically significant.

    Results: ANOVA showed a significant difference in SBS among the groups (P<0.001). The highest SBS was achieved in the TXT group (26.63±9.09 MPa), followed by TXT/S (13.69±4.23 MPa), VF/S (3.68±1.49 MPa), and VF (3.04±1.73 MPa).

    Conclusion: Saliva contamination did not have a significant effect on SBS of brackets bonded with Vertise Flow. However, it did not provide acceptable bond strength for orthodontic bracket bonding in the clinical setting.

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    Objectives: This study aimed to assess the color change (∆E00) of 7 brands of denture teeth (conventional acrylic and composite teeth) following immersion in staining solutions.

    Materials and Methods: Maxillary central incisor denture teeth made of 4 conventional acrylic resins (Vitapan, SR Vivodent PE, Beta Star and Crystal) and 3 composite resins (Finex, Emeral and Phonares II) were randomly divided into four groups (n=5). Denture teeth of different brands were immersed in tea, coffee, cola, and turmeric solutions. The solutions were incubated at 37°C. The baseline color of the teeth was measured using an intraoral spectrophotometer. The color of the teeth was measured after 24 h (∆E12), 1 week (∆E13), 2 weeks (∆E14), and 1 month (∆E15). ∆E00 was calculated and analyzed using one-way ANOVA. Pairwise comparisons were performed by the Tukey’s post-hoc test (P<0.05).

    Results: The color stability of all teeth was significantly affected by the solutions (P<0.001). The type of tooth and coloring solution had significant interactions at all times (P<0.05). Turmeric caused the maximum color change in all teeth after 1 month. Repeated measures ANOVA showed that ∆E00 of all teeth was significantly affected by the duration of immersion in the solutions (P<0.001).

    Conclusion: within the limitations of this study, 1-month immersion of denture teeth in coffee, tea and cola solution altered the ∆E values; however, they were within the acceptable range, except for Beta Star. Turmeric solution caused unacceptable color change in all denture teeth even after 24 h of immersion.


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    Objectives: Use of miniscrews has become very common in orthodontic treatment of patients. Following tissue manipulation during miniscrew placement, bacteremia may occur, which is important in patients susceptible to infective endocarditis. This study aimed to investigate the possibility of bacteremia following orthodontic miniscrew placement.

    Materials and Methods: The present quasi-experimental study was conducted on 30 orthodontic patients, including 11 males (36.7%) and 19 females (63.3%) with a mean age of 23.67±4.87 years, who required miniscrew placement in their treatment plan. Two blood samples were taken from the patients for aerobic and anaerobic cultures right before and 30-60 seconds after miniscrew placement. To investigate the presence of bacteremia, the blood samples were incubated in an automated blood culture machine for five days. The standard biological methods were used for the positive sample(s) to identify the type of bacteria. Data analysis was performed using the McNemar test.

    Results: The blood samples of 29 patients were negative for the bacteria before and after miniscrew placement. Blood sample of one patient was positive for aerobic and anaerobic bacteria after miniscrew placement. However, bacteremia was negative in the initial (preplacement) blood samples for both aerobes and anaerobes.

    Conclusion: Miniscrew placement in orthodontic patients was not associated with bacteremia.

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    Objectives: The aim of this study was to assess the microtensile bond strength of three universal adhesives to dentin and enamel.

    Materials and Methods: Sixty extracted human third molar teeth were chosen and divided into six groups regarding the adhesive (G-Premio Bond, Clearfil S3 Bond or Single Bond) and tooth surface. All the applied bonding agents were universal adhesives. The teeth were polished and the adhesives were applied; then the teeth were restored with composite resin. The samples were mounted in acrylic resin and sectioned. The specimens were subjected to a universal testing machine and the microtensile bond strength was measured. The failure mode of each specimen was determined under a stereomicroscope. Data were analyzed using two-way ANOVA (α=0.05).

    Results: The microtensile bond strength of G-Premio Bond to enamel and dentin was 11.79±8.27 and 17.55±9.47 MPa, respectively which was not significantly different from the values in Single Bond group (15.59±10.66 and 17.19±10.09 MPa to enamel and dentin, respectively; P>0.05). However, the values for Clearfil S3 Bond were 7.11±4.23 and 7.88±8.83 MPa to enamel and dentin, respectively, which were significantly lower than the values for G-Premio Bond (P<0.05). Scanning electron microscopic (SEM) images showed that the adhesive failure was dominant in both enamel and dentin groups and in all adhesive systems.

    Conclusion: G-Premio Bond and Single Bond provided higher microtensile bond strength compared with Clearfil S3 Bond. Universal adhesives with their acceptable performance can be applied in self-etch mode on both enamel and dentin.


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    Objectives: The aim of the present study was to develop and evaluate the psychometric properties of an instrument in Persian to assess the mothers’ knowledge, and perception about oral health of school children.

    Materials and Methods: A sequential exploratory mixed method design consisting of qualitative and quantitative phases was performed. We developed the questionnaire by inductive-deductive method, through a synthesis of literature review and a qualitative study with semi-structured interviews and focus group discussions. Face and content validity of the items were assessed by consulting a panel of 11 experts. In the quantitative phase, an exploratory factor analysis was performed using data from a cross-sectional study with a sample of 303 mothers. Reliability analysis with test-retest approach and Cronbach’s alpha coefficient and intra-class correlation coefficient (ICC) was done.

    Results: Pre-final version of the scale consisted of 120 items extracted from the qualitative study and literature review. After content and face validity, 92 items were chosen with the greatest agreement between experts, with a content validity index (CVI) >0.8 and content validity ratio (CVR) of 0.59. The final questionnaire covered 62 items. The overall Cronbach’s alpha was 0.94 and it ranged from 0.87 to 0.97 for the subscales. The ICC ranged from 0.91 to 0.98 (Cronbach's alpha ≥0.70).

    Conclusion: The present study introduced a valid and reliable questionnaire for assessment of the mothers’ perception regarding school children’s oral health. It can be used as a standardized measure for public health surveillance and evaluation of oral health promotion programs.


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    Objectives: We aimed to investigate oral health, oral hygiene, and associated factors in children with visual impairment aged 7-11 years.

    Materials and Methods: This cross-sectional study was conducted on 47 children with visual impairment aged 7-11 years who were selected from all three schools available for visually impaired children in Tehran in December 2018. Questions regarding age, gender, status of visual impairment, level of education of the parents, self-reported dental and gingival health, oral health, and dietary habits were asked face-to-face using the World Health Organization oral health questionnaire for children. The decayed, missing, and filled teeth index for both primary (dmft) and permanent (DMFT) dentitions was determined by clinical examination. Simplified Oral Hygiene Index (OHI-S), and bleeding on probing (BOP) were also assessed. Linear and logistic regression tests were used for statistical analysis.

    Results: Over 70% of the children were satisfied with their dental and gingival health. Daily brushing was reported by 70.2%. Over half of the children reported daily consumption of fruits and jam/honey. The mean dmft and DMFT scores were 2.85±3.21 and 0.81±1.15, respectively. The mean OHI-S was 2.09±0.58. Also, 57.4% and 34% of the children had unrestored caries in their primary and permanent teeth, respectively. BOP was seen in 78.7% of the children. A significant correlation was observed between toothache in the past 12 months and dmft score (P<0.003). Daily tooth brushing was inversely correlated with OHI-S index (P=0.02).

    Conclusion: The results highlight an urgent need for implementation of oral health programs for visually impaired children.

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    Objectives: Molar-incisor hypomineralization (MIH) lesions are common in children. The prevalence of MIH is variable in different communities. However, information regarding the prevalence of MIH in the Iranian population is limited. This study sought to assess the prevalence and etiological factors of MIH in 7-12-year-old children in Tehran.

    Materials and Methods: This descriptive, cross-sectional study evaluated 1028 elementary students between 7-12 years, selected from different districts of Tehran in 2017. The frequency of MIH in the maxillary and mandibular molars and incisors was determined by clinical examination. In order to assess the role of different factors in the development of MIH, a questionnaire was filled out by the mothers regarding problems during their pregnancy, medical history of children, and age of occurrence of systemic conditions (if any). The effect of different factors on the development of MIH was analyzed by the logistic regression test.

    Results: The prevalence of MIH was found to be 25.6%. The delivery condition of the mother (P<0.001), history of urinary tract infection (P<0.011), history of chickenpox (P<0.018), and frequent use of amoxicillin during childhood (P<0.041) significantly affected the occurrence of MIH. The most commonly involved teeth were the mandibular left first molars.

    Conclusion: The prevalence of MIH in our study population was within the range reported in the literature. Considering the relatively high prevalence of MIH in 7-12-year-old children, pediatric dentists should pay special attention to treatment of MIH

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    Objectives: We aimed to find the main concerns of patients undergoing active orthodontic treatments and their orthodontic treatment-related (OTR) problems during the coronavirus disease-2019 (COVID-19) pandemic.

    Materials and Methods: A researcher-made questionnaire addressing several aspects of the effects of COVID-19 pandemic on treatment was distributed among 181 orthodontic patients receiving active treatment. Anxiety, concern, problems, and willingness to attend orthodontic appointments and to undergo other dental procedures was questioned. The correlation of gender, age, COVID-19-related anxiety and OTR anxiety was statistically analyzed. Patient satisfaction level with different aspects of dental-clinic performance was also evaluated.

    Results: The participants included 117 females and 64 males, of which 94% adhered to the pandemic restrictions. The mean COVID-19-related- and OTR-anxiety were 51.7% and 52.7%, respectively. Higher COVID-19-related anxiety was significantly correlated with higher OTR anxiety (P<0.001). There was an inverse correlation between general COVID-19-related anxiety and OTR anxiety and willingness to attend orthodontic appointments (P<0.05). A positive insignificant (P=0.07) correlation existed between age and willingness to attend appointments. The main concern was prolongation of treatment and the most common problem was irritation of oral soft tissues by appliances. The majority (65.3%) were willing to attend their orthodontic appointments. Orthognathic surgery (62%) had the highest while, dental restorations and radiography had the lowest refusal rates (9.9%).

    Conclusion: COVID-19 pandemic significantly affected orthodontic treatment. The level of COVID-19-related anxiety was moderately high and patients were concerned about the impact of lockdown on their orthodontic treatment outcome. Young adults demonstrated higher levels of stress than other age-groups.

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    Objectives: Maxillary sinus pathological conditions, like thickening of the Schneiderian membrane, can influence the outcomes of augmentation procedures and implant treatment. The present study aimed to evaluate the relationship between the residual ridge height and maxillary sinus membrane thickening.

    Materials and Methods: A total of 240 cone-beam computed tomography (CBCT) images of the maxillary sinus of 141 patients (62.1% males and 37.9% females, bilateral in 99 patients and unilateral in 42 patients) who were candidates for implant placement were evaluated. The CBCT scans were subsequently assessed for the following variables: residual ridge height, sinus membrane thickening at future implant(s) site(s), the ostium patency, and presence of periapical lesion adjacent to the edentulous area.

    Results: The total prevalence of sinus membrane thickening (66.2%) was sub-classified as follows: flat in 53.7%, polypoid in 12.1%, and complete opacification in 0.4%. The prevalence of sinus membrane thickening was higher in male participants. It was revealed that age had no significant relationship with presence of a periapical lesion or sinus membrane thickening (P>0.05). Membrane thickening was detected in all sinuses with obstructed ostium. Reduced residual ridge height was significantly associated with higher sinus membrane thickening at the second premolar and first molar sites (P<0.05).

    Conclusion: Maxillary sinus membrane thickening (mostly with flat appearance) is frequently observed on CBCT scans taken prior to augmentation and implant placement. This, in return, may trigger a reduction in ridge height.

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    Objectives: This study compared the effects of fluoride mouthwashes on surface topography of orthodontic wires, and static and kinetic frictional forces between the stainless steel (SS) orthodontic brackets and SS and nickel-titanium (NiTi) archwires.
    Materials and Methods: This in vitro, study evaluated 240 standard SS maxillary central incisor brackets and 0.018, and 0.025×0.019 inch NiTi and SS archwires. The wire-bracket sets (different combinations of wire diameters and types) were exposed to artificial saliva (control), 0.05% sodium fluoride (NaF) for 1 minute daily,
    or 0.2% NaF for 1 minute, weekly (37°C) for 3 months. The wires were pulled in bracket slots by 5 mm in a universal testing machine (10 mm/minute). The static and kinetic forces were measured. The surface topography of wires was inspected under a scanning electron microscope (SEM; x500). Data were analyzed by SPSS 25.
    Results: The mean static and kinetic frictional forces of 0.025×0.019 inch NiTi wire in 0.05% NaF group were significantly greater than SS wire (P=0.000). The mean kinetic frictional force in 0.05% NaF was significantly greater than 0.2% NaF and artificial saliva for all wires (P=0.001). The mean static and kinetic forces in 0.2%
    NaF were significantly greater than in artificial saliva (P=0.025). In all groups, larger wires showed higher mean frictional forces (P=0.000). SEM results revealed higher wire surface roughness in 0.05% NaF followed by 0.2% NaF group.
    Conclusion: Weekly use of 0.2% NaF mouthwash is recommended during sliding mechanics to minimize frictional forces between the SS and NiTi wires and SS brackets.

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    Objectives: Parents are aware of the importance of anterior tooth esthetics in their children. Children also pay attention to their appearance more than ever. Today, charcoal has been added to toothpastes. This study aimed to investigate the degree of bleaching and abrasion of charcoal toothpaste on primary teeth.

    Materials and Method: This in-vitro study was performed on 30 extracted primary teeth. Initially, the samples were polished, cut, and mounted in blocks of putty. The samples were placed in a coffee solution and then the tooth color was measured by a spectrophotometer and the initial surface profile was measured by a profilometer. The samples were brushed back and forth by the brushing machine with 20 gr Bancer, Beverly, and Colgate toothpastes (mixed with 40 ml of distilled water) for 2000 times (equivalent to 3 times a day for 1.5 months). A color determination was performed again and a second surface profile was measured. The data were analyzed by one-way ANOVA, ANCOVA and paired t-test.

    Results: The results of this study showed that all three Beverly, Bencer and Colgate whitening toothpastes increased the surface profile and made significant statistical changes in the roughness of dental specimens (P=0.01, P=0.005, P=0.001). The statistical study of the data did not show a significant difference between the groups in terms of abrasion and whitening properties (P=0.78, P= 0.99).

    Conclusion: Three whitening toothpastes whiten primary teeth and increase their surface roughness. These three toothpastes are not statistically different in terms of abrasion and whitening properties.

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    Objectives: The present study aimed to investigate the effect of preheating on the color stability and surface roughness of a silorane-based composite resin.

    Materials and Methods: A total of 44 Filtek P90 composite resin disks, (10mm×1mm), were fabricated using plastic molds and were divided into two groups. In group 2, the composite resin syringes were placed in a thermostatically controlled water bath at 55‒60°C before preparing the disks. After polishing the samples with silicon carbide papers, they were stored in distilled water for 48 hours. Roughness and color parameters were then measured in two stages: immediately after retrieval from distilled water and after 40 days of storage in tea solution. Finally, the differences in roughness and color parameters were recorded. Independent sample t-test and regression analysis were used at a significance level of P<0.05.

    Results: Based on the findings of the present study, there was no significant difference among the mean ∆E values (P=0.4); however, a significant difference in mean surface roughness (P=0.01) was found between the two groups. Regression analysis showed a significant relationship between the study groups in terms of surface roughness and ΔE values​ (preheated: r2 = 0.73; non-preheated: r2= 0.76).

    Conclusion: Filtek P90 silorane-base composite showed ΔE>3.3 and surface roughness above 0.2µ under preheated and non-preheated conditions and discoloration increased following preheating.


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    Objectives: This study aimed to evaluate the effect of an educational intervention on oral health-related knowledge, attitude, and practice of medical students.

    Materials and Methods: This study was performed on the fifth-year medical students attending an elective oral health course at the Faculty of Dentistry of Tehran University (intervention group) and 25 other students attending another elective course (control group) in 2018. A 2-week internship program including 6 sessions of a workshop program plus 2 days of school field and 2 days of attending dental departments was designed for the intervention group. Before and after the intervention, students completed a questionnaire and their simplified debris index was calculated. Statistical analysis was performed using SPSS version 24 by paired-sample t-test and general linear regression.

    Results: The mean age of the participants was 24.84±1.31 years in the intervention group and 23.64±1.28 years in the control group. There were 14 (56%) males in the intervention group and 16 (64%) males in the control group. At baseline, the mean knowledge, attitude and practice scores of the control and intervention groups were 26.28, 14.20 and 10.88, and 27.84, 15.80, and 9.36, respectively. After the intervention, the knowledge, attitude, debris index and willingness to adhere to oral health measures significantly improved (P<0.05).

    Conclusion: Oral health-related knowledge, attitude and practice of medical students were not desirable at baseline. The present study showed that even a short-term intervention in this field was effective to improve the oral health concepts in this group.

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    Objectives: Any change in the sintering process can directly affect the micro-structure and properties of zirconia. This study sought to assess the effect of sintering temperature on flexural strength of IPS e.max ZirCAD MO Ivoclar (EZI) and CopraSmile White Peaks Symphony (WPS) zirconia blocks.

    Materials and Methods: In this in vitro, experimental study, 30 EZI and 30 WPS zirconia blocks measuring 10 x 10 x 1 mm were milled and sintered at 1440, 1500 and 1530°C in three subgroups. The flexural strength of the specimens was measured by a testing machine with piston-on-3-ball method according to ISO2015. Data were analyzed using one-way ANOVA.

    Results: The mean flexural strength was 1.31±0.49, 1.09±0.24 and 1.29±0.48 MPa in 1440, 1500, and 1530°C subgroups of EZI, and 1.44±0.61, 1.18±0.35, and 1.33±0.54 MPa in 1440, 1500, and 1530°C subgroups of WPS zirconia, respectively. Two-way ANOVA revealed that the effects of zirconia type (P=0.484), temperature (P=0.258) and their interaction (P=0.957) on flexural strength were not significant.

    Conclusion: Increasing the sintering temperature from 1440°C to 1530°C did not increase the flexural strength of EZI or WPS zirconia. 

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    Objectives: Considering the side effects of chlorhexidine (CHX), which is currently the gold-standard antimicrobial mouthwash, this study aimed to compare the effects of Green Kemphor and CHX mouthwashes on tooth staining and gingivitis.

    Materials and Methods: This randomized controlled crossover clinical trial evaluated 38 patients requiring CHX mouthwash following oral surgery and periodontal therapy. The patients were randomly assigned to CHX and Kemphor groups (n=19). In CHX group, patients used CHX mouthwash in the first 2 weeks, and after a 4-day washout period, they used Kemphor mouthwash for 2 weeks. This order was reverse in the Kemphor group. Gingivitis was evaluated using the Silness and Loe gingival index (GI), and tooth staining was evaluated by the Lobene index at 0 (baseline), 2 and 4 weeks. Data were analyzed by paired t-test.

    Results: CHX mouthwash significantly decreased the GI and increased tooth staining (gingival stains, body stains, and stain extent) at 2 weeks (P<0.05). Kemphor mouthwash significantly decreased the GI and increased tooth staining after 2 weeks (P<0.05). The GI in Kemphor group was significantly lower than that in CHX group at 4 weeks (P<0.05). Also, the tooth staining parameters in the Kemphor group were significantly lower than the corresponding values in the CHX group at 2 and 4 weeks (P<0.05).

    Conclusion: Kemphor had higher efficacy for reduction of GI and caused less tooth staining than CHX; thus, it may be recommended for use as an alternative to CHX.

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    Objectives: ‘Field of view (FOV) size’ affects the quality of radiographic images and the radiation dose received by patients. In cone-beam computed tomography (CBCT) FOV should be selected according to therapeutic purposes. While aiming for the highest diagnostic image quality, the radiation dose should be kept to a minimum to reduce the risk for patients. The purpose of this study was to assess the effect of different sizes of FOV on contrast-to-noise ratio (CNR) in five different CBCT units.

    Materials and Methods: In this experimental study, CBCT scans were taken from a dried human mandible containing a resin block fixed to the lingual cortex and a resin ring was used to simulate soft tissue during scans. Five CBCT units including, NewTom VGi, NewTom GiANO, Soredex SCANORA 3D, Planmeca ProMax, and Asahi Alphard 3030 were evaluated. Each unit had 3 to 5 different FOVs. Images were obtained and analyzed with ImageJ software and CNR was calculated in each image. ANOVA and T-test were used for statistical analysis (P<0.05).

    Results: Comparison among different FOVs of each unit showed significant CNR reductions in small FOVs (P<0.05). Similar FOV sizes of different CBCT devices were also compared and demonstrated significant differences (P<0.05).

    Conclusion: A direct relationship between FOV size and CNR was observed in all five CBCT units, but differences in exposure parameters of these units led to variable CNR in FOVs with similar sizes.

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    Objectives: Considering the high prevalence of consumption of iron drops, and the resultant reduction in microhardness of primary enamel, this in vitro study aimed to assess the effects of Sucrosomial® iron and iron drop diluted with natural fruit juice on microhardness of primary enamel. 

    Materials and Methods: This in vitro, experimental study evaluated 45 extracted sound primary anterior teeth, that were randomly assigned to three groups (n=15) of Sideral, Irofant, and Irofant + natural apple juice. The titratable acidity and pH of solutions were measured. After measuring the baseline microhardness by a Vickers hardness tester, the teeth in the three groups were exposed to the respective iron drop solutions at 37°C for 5 minutes. They were then rinsed with distilled water, and their secondary microhardness was measured. Data were analyzed using the dependent Student t-test, ANOVA, and ANCOVA (alpha=0.05).

    Results: Irofant had the lowest pH and the highest titratable acidity among the tested solutions. A reduction in enamel microhardness occurred in all groups after exposure to iron drops (P=0.0001). The reduction in microhardness was significantly greater in Irofant group compared with Irofant + natural apple juice (P=0.0001). Also, the reduction in microhardness was significantly greater in Irofant + natural apple juice compared with Sideral iron drop group (P=0.0001).

    Conclusion: Sideral iron drop with Sucrosomial iron has minimal adverse effect on microhardness of primary enamel. Also, dilution of iron drops with natural apple juice can be suggested as an effective strategy to decrease their adverse effects on microhardness of primary enamel.

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    Objective: Dental educational curricula are under constant modification and improvement. However, designing a comprehensive, efficient, and flexible curriculum is still challenging for the authorities. An efficient curriculum should obviate the educational needs of students and promote their knowledge and expertise for future practice. Time planning of clinical rotations is highly important for optimization of the learning process. This study aimed to compare the efficacy of two different timing models of clinical rotations, namely four versus two rotations in each semester.

    Materials and Methods: A total of 74 dental students and 54 faculty members of Tehran University of Medical Science that experienced both rotation models for two consecutive years (2018 and 2019) participated in this study. A questionnaire was designed to assess different aspects of the two timing-models.

    Results: A one-sample t-test indicated that students' and faculty members' mean perception were significantly better regarding the two-rotation program.

    Conclusion: This study indicated that changing the time planning of educational rotations can affect different aspects of education.


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    Objectives: Assessment of patients’ knowledge regarding infection control in dentistry can help professionals in the development of protocol planning to minimize the risk of disease transmission through dental procedures. The aim of this paper is to assess the knowledge level about infection control of patients presenting to the dental clinic of the School of Dentistry, Tehran University of Medical Sciences in 2020.

    Materials and Methods: The draft of the questionnaire was designed with eight domains regarding infection control in dentistry including the coronavirus disease-2019 (COVID-19). The content validity of the questionnaire was assessed by six experts and 10 laypersons. The reliability of the questionnaire was assessed by the test-retest method. Two-hundred and forty-four patients (over 20 years of age) were selected based on non-random convenience sampling method, and participated in this study in July 2020. According to the difficulty coefficient, differential coefficient, and the opinion of the experts about the questionnaire filled out by the participants, 24 questions were selected out of 43 for the final version.

    Results: The intra-rater reliability indices were ≥75% and the scale-content validity indices for relevance, simplicity, and clarity were 87.80%, 93.75% % and 93.33%, respectively. The knowledge score of patients was 76.83%±11.58% which was not correlated with the level of education, age or gender (P>0.05).

    Conclusion: The knowledge level of patients presenting to the dental clinic of Tehran University of Medical Scineces measured by a valid and reliable researcher-made questionnaire was acceptable about infection control.

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