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


Happy Persian New Year 1402



Nowruz is the Persian new year and marks the beginning of spring and revival of nature. It means “New Day” in Farsi and it is the first day of the month of Farvardin (March 21st) in the Persian calendar.

On behalf of the Editorial Office of Frontiers in Dentistry we wish all our readers, contributors, authors and reviewers a HAPPY NOWRUZ and extend our sincere gratitude to all those who helped make this Journal a success. May you have a great year filled with prosperity and joy.

Read more about Happy Persian New Year 1402

Current Issue

Vol 20 (Continuously Published Article-Based)

Original Article

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    Objectives: The combination of mineral trioxide aggregate (MTA) and 2% chlorhexidine (CHX) has been recently introduced as an intracanal medicament. The aim of this study was to evaluate the potential cytotoxic effects of MTA mixed with 2% chlorhexidine gel on human periodontal ligament stem cells (PDLSCs) and compare it with other common endodontic regeneration medicaments.

    Materials and Methods: Minimum inhibitory concentration and minimum bactericidal concentration of six experimental groups against Enterococcus faecalis was determined. The study groups consisted of RetoMTA mixed with 2% chlorhexidine gel (MTA+CHX), calcium hydroxide (CH), CH mixed with CHX gel, two concentrations of double antibiotic paste, and 2% CHX. The direct cytotoxic effect of minimum bactericidal concentration was evaluated by MTT on PDLSCs on days 1, 3, and 7. One-way ANOVA and post hoc tests were used for data analysis (P<0.05).

    Results: The viability of cells treated with MTA+CHX decreased significantly over time (P<0.05) making this group the most cytotoxic intracanal medicament on the 3rd and 7th days of treatment. On day one, the highest viability percentage was detected in the CH+CHX group followed by the CHX group. On day 3, CH+CHX and CHX groups displayed the highest viability percentage. On day 7, the highest viability was observed in the CHX group, which showed no significant difference with the control group (P=0.12).

    Conclusion: Regarding the antimicrobial potency of intracanal medicaments at minimum bactericidal concentration levels, CHX gel appears to be the least cytotoxic drug, while MTA+CHX shows the highest reduction in viability percentage

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    Objectives: This study assessed the fracture resistance of zirconia crowns with four framework designs, fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) technology.

    Materials and Methods: In this experimental study, a maxillary central incisor was prepared and scanned with a CAD/CAM scanner, and 40 frameworks with 4 designs (N=10) were fabricated as follows: simple core, dentine core with a design similar to dentine, 3mm trestle design collar in the lingual aspect with proximal buttresses, and monolithic or full-contour. After porcelain applying and 20h immersion in distilled water (37°C), crowns were cemented on metal dies using zinc phosphate cement. Fracture resistance was measured by a universal testing machine. Data were analyzed with one-way ANOVA (alpha=0.05).

    Results: Fracture resistance was maximum in the monolithic group, followed by the dentine core, trestle design, and simple core groups, respectively. The mean fracture resistance of the monolithic group was significantly higher than that of the simple core group (P<0.005).

    Conclusion: Zirconia restorations with frameworks that provided higher and more support for porcelain, showed increased fracture resistance

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    Objectives: The present study aimed to evaluate the efficacy of ginger essential oil spray for elimination of Candida albicans (C. albicans) adhering to self-cure acrylic plates.

    Materials and Methods: In this experimental study, 120 self-cure acrylic discs were contaminated with C. albicans and randomly divided into four main groups: exposure to ginger essential oil, nystatin (positive control), distilled water (negative control), and no exposure. The minimum inhibitory concentration (MIC) of ginger oil and nystatin was determined by the microdilution test. The stability of C. albicans was determined by culturing the samples of treated acrylic plates and comparing the mean number of remaining colonies. Data were analyzed using the Kruskal-Wallis test followed by Dunn test with Bonferroni correction.  P<0.05 was considered significant

    Results: The MIC of ginger essential oil and nystatin was found to be 1560µg/mL and 4µg/mL, respectively. The differences between the mean count of C. albicans colonies before (10175±10730.25) and after the exposure to ginger essential oil (542.86±464.81) and nystatin (257.14±247.67) was statistically significant (P<0.001). The mean number of C. albicans colonies after spraying with nystatin was not significantly different compared with ginger essential oil (P=0.204). The efficacy of nystatin and ginger essential oil at each time was significantly more than distilled water (P<0.001). At 10 and 15min, there was no significant difference between nystatin and ginger essential oil groups (P=0.05).

    Conclusion: Ginger essential oil spray was found to be a simple and effective method for elimination of C. albicans adhering to acrylic discs.

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    Objectives: The purpose of this randomized parallel clinical trial was to assess and compare the efficacy of 97% Aloe Vera (AV) gel and 94.7% AV juice against an active control (0.05% Clobetasol Propionate) in the treatment of oral lichen planus (OLP).

    Materials and Methods: Age and sex matched patients with histologically proven OLP were divided into two groups. One group received 97% AV gel for topical application and 10ml 94.7% AV juice to consume twice daily. The active control group received topical 0.05% Clobetasol Propionate ointment twice daily. Treatment lasted two months followed by four months of observation. Monthly evaluation of various clinical features of OLP was done using the OLP disease scoring criteria. Burning sensation was evaluated using Visual Analog Scale (VAS). Mann Whitney–U (followed by Bonferroni adjustment) and Wilcoxon’s signed-rank tests were used for intergroup and intragroup comparisons, respectively. Interclass correlation-coefficient test was applied to assess the intra-observer variation (P<0.05).

    Results: In total, 41 females and 19 males participated in this study. The most common site was the buccal mucosa followed by the gingivobuccal vestibule. The reticular variant was most frequently encountered. Wilcoxon’s signed-rank test showed significant differences in both groups between baseline and end-of-treatment for VAS, site-score, reticular/plaque/papular score, erosive/atrophic score and OLP disease score (P<0.05). Mann–Whitney revealed significant difference between both groups in the 2nd, 3rd and 4th months (P<0.0071).

    Conclusion: Clobetasol Propionate is more effective for OLP management but in our study AV proved to be a safe treatment alternative for OLP management.

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    Objectives: This study was performed to find the most common types of maxillofacial fractures and their management in 3 to 18-year-old individuals referred to the Department of Oral and Maxillofacial Surgery at Shariati Hospital in Tehran, during a 9-year period.

    Materials and Methods: This retrospective study evaluated the records of 319 patients with maxillofacial fractures between 2012-2020, ranging in age from 3 to 18 years. Data regarding the etiology and location of the fracture, age, gender, and treatment approach were retrieved from the archival records and analyzed.

    Results: A total of 319 patients were included in the study, out of which, 255 (79.9%) were males and 64 (20.1%) were females. Motor-vehicle accidents were the most common cause of trauma (N=124, 38.9%). We recorded 605 fractures and among them, the parasymphysis (N=131, 21.6%) was the most common site of isolated fractures. Type of treatment varied depending on the fracture type and degree of displacement of the broken segments. It consisted of open reduction and internal fixation, and closed reduction procedures, which included the use of arch bars, ivy loops, lingual splints, and circummandibular wirings.

    Conclusion: Analysis of the results revealed that the severity of injury increased with age. Older individuals had higher a number of fracture sites and experienced greater displacement of the broken segments.

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    Objectives: Age estimation is a crucial aspect of forensic odontology, and the Tooth Coronal Index (TCI) has been widely used for forensic purposes in determining age. The aim of this research was to evaluate the effectiveness of TCI in age estimation.

    Materials and Methods: A retrospective study was conducted, and TCI was calculated for the mandibular first premolar in 700 digital panoramic radiographs. Age was divided into five groups: 20-30 years, 31-40 years, 41-50 years, 51-60 years, and >61 years. Bivariate correlation was used to establish the relationship between TCI and age. Linear regression was calculated for the different age groups and genders. Inter-observer reliability and agreement were assessed using one-way ANOVA. P-values less than 0.05 were considered statistically significant.

    Results: Comparison of the mean difference from actual age showed underestimation in males aged 20-30 years and overestimation in males over 60 years of age. The least difference between actual and calculated age was found in females aged 31-40 years. Inter-age comparison using ANOVA for females demonstrated a statistically highly significant difference from actual age in all age groups (P<0.01), with the highest mean in females aged 51-60 years and the lowest in females aged 31-40 years. Inter-group comparison of mean TCI revealed statistically non-significant differences in males and statistically highly significant differences in females (P<0.01).

    Conclusion: Age estimation using TCI on mandibular first premolars can be recommended as an easy, non-invasive, and less time-consuming method. This study suggests that regression formulas were more accurate for males aged 31-40 years

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    Objectives: Vitamin D deficiency appears to have a major effect on periodontal tissue health. The present study aimed to assess the association of the serum level of 25-hydroxyvitamin D and chronic periodontitis in postmenopausal women.

    Materials and Methods: This research was done on 30 postmenopausal women with chronic periodontitis who all had at least 20 natural teeth. Intravenous blood samples were taken from the study population at baseline and after completion of non-surgical periodontal treatment. This was followed by assessment of serum levels of 25-hydroxyvitamin D. Next, clinical parameters of all teeth except for third molars were measured, which included pocket depth (PD), gingival index (GI), and plaque index (PI). Data were analyzed by paired t-test and its non-parametric equivalent, the Wilcoxon test. P<0.05 was considered significant.

    Results: The mean PD, PI and GI before and after the intervention were significantly different (P<0.05). There was, however, no significant difference between the mean vitamin D concentrations before and after treatment (P>0.05).

    Conclusion: According to the results obtained in the present study, there is no association between serum vitamin D concentrations and chronic periodontitis in postmenopausal women.

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    Objectives: This study aimed to assess the microtensile bond strength (µTBS) of etch-and-rinse (E&R), self-etch (SE), and universal adhesives to superficial and deep dentin.

    Materials and Methods: In this in vitro study, 40 sound third molars were randomly divided into two main groups of superficial and deep dentin. Based on our classification, superficial dentin was right beneath the deepest occlusal groove, and deep dentin was 2mm beneath the deepest occlusal groove. Each group was divided into 4 subgroups (n=20) for application of Adper Single Bond 2 (ASB), Clearfil SE Bond (CSE), and Scotchbond Universal (SBU) in E&R and SE modes along with Charisma Smart composite resin on dentin. The specimens were incubated in distilled water at 37°C for 24 hours and their µTBS was then measured. The mode of failure was determined under a stereomicroscope at ×40 magnification. Data were analyzed by one-way ANOVA (alpha=0.05).

    Results: The highest µTBS belonged to the superficial dentin/SBU/E&R group. The µTBS was significantly higher in superficial dentin than deep dentin for all adhesives (P=0.005). There was no significant difference in mode of failure among the groups.

    Conclusion: Based on the results obtained in the present study, type of bonding agent and application mode affected µTBS. In use of universal adhesive, E&R mode can improve µTBS.

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    Objectives: The durability of composite restorations is directly affected by the mechanical properties of the composite. The aim of this study was to evaluate the hardness and wear resistance of self-adhesive flowable composite (SAF) in comparison with conventional flowable composites.

    Materials and Methods: In this in vitro study, 50 composite specimens were prepared in brass molds with 10mm ×10mm ×2mm and divided into five groups (n=10). Specimens included three conventional flowable composites (Grandio flow, Filtek flow and Admira fusion flow), one self-adhering flowable composite (SAF, Vertise flow) and a microhybrid composite (filtek z250). After polishing, the micro-hardness of the specimens was measured in a Vickers hardness device, and the specimens were then subjected to 5000, 10000, 20000, 40000, 80000 and 120000 wear cycles in a wear tester. One-way ANOVA/Games-Howell, Kruskal Wallis, and Friedman tests were used for statistical analysis. The significance level was set at P<0.05.

    Results: The surface micro-hardness of the SAF was significantly lower than that of the microhybrid composite (P=0.01). There was no significant difference between the surface hardness of the different tested flowable composites (P>0.05). Also, the wear resistance of the studied composites was not significantly different in various cycles (P>0.05).

    Conclusion: Based on our results, SAF would not be an ideal substitute for conventional flowable composites in high-stress areas.

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    Objectives: Temporomandibular disorders (TMDs) include a series of signs and symptoms in the temporomandibular joints (TMJ) and muscles of mastication, which are associated with or caused by parafunctional habits. Many of these patients also suffer from lumbar pains. This study aimed to evaluate the effectiveness of treating parafunctional habits in alleviating symptoms of TMD and lower back pain.

    Materials and Methods: This phase II clinical trial was conducted on 136 patients suffering from TMDs and lumbar pain, who consented to participate in this study. They were provided with instructions on how to discontinue their parafunctional habits including clenching and bruxism. The Helkimo and Rolland Morris questionnaires were used to assess TMD and lower back pain, respectively. Data were statistically analyzed using paired Student's t-test, Wilcoxon, Mann-Whitney, and Spearman correlation tests, with the significance level set at P<0.05.

    Results: The mean severity score of TMD significantly decreased after the intervention. Following treatment of TMD, the mean severity score of lumbar pain decreased from 8 to 2 (P=0.0001).

    Conclusion: Based on our findings, it appears that the elimination of parafunctional habits improves TMD and lumbar pain.

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    Objectives: Injuries to the maxillofacial region during contact sports is a well-known issue. Protective measures have been advised to prevent and reduce these problems. Awareness regarding the role of mouthguards in preventing temporomandibular joint (TMJ) injuries during contact sports, is limited. The aim of the present study was to assess awareness regarding the use of mouthguards during contact sports and incidence of TMJ injuries in sportspersons.

    Materials and Methods: Eighty-six individuals training in contact sports were enrolled in the present study based on our inclusion and exclusion criteria. A questionnaire and clinical examination were used to assess TMJ pain, clicking, deviation, mouth opening, and locking.

    Results: The percentage of sportspersons aware of various protective gears was 23.8%. The awareness of TMJ injuries following contact sports was 6.9%, and 70.3% of the sportspersons were estimated to wear mouthguards. Clinical assessment of sportspersons using mouthguards revealed pain in 18.6% and clicking in 17.4% of the study subjects. The incidence of TMJ pain and clicking in individuals who did not use mouthguards were 81.4% and 82.6%, respectively.

    Conclusion: Application of mouthguards can reduce the incidence of TMJ injuries in contact sports. They also contribute significantly to the overall dental health of the athletes, as well as improving their overall athletic performance and decreasing the likelihood of other types of oral and facial injuries.

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    Objectives: This study aimed to assess the effect of different forms of fluoride application on surface roughness of rhodium-coated nickel-titanium (NiTi) orthodontic wires.

    Materials and Methods: This randomized clinical trial was conducted on 15 patients randomly divided into three groups: toothbrush with Oral-B toothpaste only, Oral-B toothpaste, and daily mouthwash, Oral-B toothpaste, and sodium fluoride gel. The surface roughness indices of orthodontic wires including arithmetic mean height (Sa), root mean square height, root mean square gradient, developed interfacial area ratio (Sdr) and maximum surface height were measured by atomic force microscopy at baseline and after 6 weeks of application in the patients’ mouths. Data were analyzed by paired t-test, ANOVA, Games-Howell, and Tukey-HSD tests (P<0.05).

    Results: All surface roughness parameters in all three groups showed a significant increase after intervention, except for Sa in the toothpaste-only group (P=0.057) and Sdr in the sodium fluoride gel group (P=0.064).

    Conclusion: The surface roughness of rhodium-coated NiTi orthodontic wires increases following the use of different forms of fluoride.

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    Objectives: This study aimed to evaluate the pH changes and penetration of hydrogen peroxide into radicular dentin when different protective bases were used with and without a bonding agent.

    Materials and Methods: In this in-vitro experimental study, 70 single-rooted bovine teeth were instrumented and obturated with gutta-percha. The gutta-percha was removed 3mm below the cementoenamel junction (CEJ) and the teeth were divided into seven groups (n=10). In each group, 2mm base (1mm apical to the CEJ) was applied as follows:  TheraCal LC, TheraCal LC plus SE Bond, Lime-Lite, Lime-Lite plus SE Bond, Ionoseal, Ionoseal plus SE Bond, and resin-modified glass ionomer (RMGI). The teeth were placed in vials containing distilled water, and pH values and molar concentration of the medium surrounding the teeth were recorded immediately after internal bleaching with 35% hydrogen peroxide. The pH values were also recorded at 1, 7, and 14 days following renewal of the medium. Data were analyzed with t-test, one-way ANOVA, and Kruskal-Wallis test. 

    Results: After bleaching, the medium pH became acidic in all groups. There were no significant differences among groups in the mean pH of the medium after bleaching (P=0.189). Moreover, there were no significant differences among the study groups with respect to hydrogen peroxide concentration (P=0.895).

    Conclusion: Intra-orifice barriers such as light-cure resin-modified calcium hydroxide, light-cure resin-reinforced glass ionomer, and light-cure calcium silicate can be as effective as RMGI in providing coronal seal during intracoronal bleaching.

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    Objectives: One of the most common methods used for the reconstruction of endodontically treated teeth is post and core and crown. Various factors such as the remaining tissue above the cutting margin (ferrule) affect the fracture resistance of teeth restored with post and core and crown. This study aimed to investigate the effect of ferrule/crown ratio (FCR) on the strength of maxillary anterior central teeth using finite element analysis.

    Materials and Methods: A 3D scan of a central incisor was obtained, and the data were transferred to Mimics software. Then, a 3D model of the tooth was designed. Next, 300N load was applied at a 135° angle to the tooth model. Force was applied to the model both horizontally and vertically. Ferrule height was considered to be 5%, 10%, 15%, 20%, and 25% in the palatal surface and 50% in the buccal surface. The length of post in the model was 11, 13, and 15mm.

    Results: By increasing the FCR, stress and strain distribution increased in the dental model and decreased in the post itself. As the horizontal angle of load application increased, the level of stress and strain created in the dental model increased as well. The closer the force application site to the incisal area, the higher the stress and strain would be.

    Conclusion: Maximum stress was inversely correlated with FCR and post length. In ratios of 20% and higher, insignificant changes occurred in stress and strain patterns in the dental model.

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    Objectives: The current study aimed to assess the cyclic fatigue resistance of two nickel-titanium (NiTi) rotary files after immersion in 5% sodium hypochlorite (NaOCl) and Deconex.

    Materials and Methods: In this in vitro study, 90 new M3 Pro Gold size 25.06 and size F2 SP1 files were tested. Forty-five files of the same brand were randomly distributed into three groups (n=15) and submitted to the following immersion protocol for 5 minutes at room temperature: no immersion (control group), immersion in 5% NaOCl, and immersion in Deconex. The cyclic fatigue resistance of the files was then measured in a custom-made tester. Two-way ANOVA was applied to compare the cyclic fatigue resistance of SP1 and M3 NiTi rotary files based on the type of disinfectant solution. Post-hoc LSD test was used for pairwise comparisons and P<0.05 was considered significant.

    Results: Two-way ANOVA indicated a significant difference in the mean cyclic fatigue resistance of M3 and SP1 NiTi rotary files. The M3 files immersed in NaOCL displayed the lowest and the SP1 files immersed in Deconex showed the maximum cyclic fatigue resistance. The effect of type of disinfectant solution (P<0.001) and type of NiTi file (P<0.001) on cyclic fatigue resistance was statistically significant.  

    Conclusions: The cyclic fatigue resistance of NiTi rotary instruments can be affected by immersion in disinfectants, and the specific type of file and disinfectant used will ultimately determine the extent of this impact.

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    Objectives: Dental caries is a common chronic disease amongst children and are typically evaluated using the DMFT/deft index (decayed, missing, and filled teeth for permanent dentition/decayed, extracted, and filled teeth for primary dentition). To address the limitations associated with these indices, alternative assessment tools such as the Caries Assessment Spectrum and Treatment (CAST) index and Ora test have been developed. These methods aim to estimate caries activity within the oral cavity more accurately. The objective of our study was to evaluate and correlate caries activity in 5-to-8-year-old children using Ora test and CAST index.

    Materials and Methods: Thirty schoolchildren between the ages of 5 and 8 years were selected and allocated into two groups (n=15) with DMFT/deft scores of <5 (group A) and >5 (group B). Two separate blinded examiners administered the assessments by first determining CAST scoring, which was followed by Ora test. Statistical analysis was performed using Pearson correlation test and significance was set at P≤0.05.

    Results: The mean time for color change of Ora test, was 118.53±23.28 minutes in group A and 53.33±15.07 minutes in group B. CAST severity scores were 3.67±2.08 and 15.7±9.70 for groups A and B, respectively. Time taken for color change in Ora test and CAST scores showed a significant negative linear relationship (P=0.039).

    Conclusion: Based on the negative correlation between CAST scores and Ora test, it may be postulated that microbial activity is directly related to caries activity in 5-to-8-year-old children.

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