Journal of Dental Medicine

Poly (lactic-co-glycolic acid) is a biodegradable polymer which has used in a different fields of medical applications. As PLGA is approved by FDA(food and drug administration) the range of this usage is increasing in comparison to the past. Particularly, PLGA are also developed for the dental field in the form of scaffolds, films, membranes, microparticles, or nanoparticles. PLGA scaffolds have been used to regenerate damaged tissues together with stem cell-based therapy. There is solid evidence thatthe development of PLGA microparticles and nanoparticles may be beneficial to a wide range of dental fields such as endodontic therapy, dental caries, dental surgery, dental implants, or periodontology. The aim of the current paper was to review the recent advances in PLGA materials and their potential uses in Dentistry via exploring related literature during 2004 till 2016 in Science Direct and PubMed.

Background and Aims: Cleft lip and palate patients require orthodontic treatments during their childhood and adolescence. Tweed diagnostic triangle as well as cephalometric assessments provides important data regarding the skeletal patterns for the treatment and diagnostic purposes. The present study determined the cephalometric changes of Tweed triangle in the cleft lip and palate patients compared to normal patients.

Materials and Methods: In total, 101 cleft and palate patients as well as 95 normal individuals with the balanced age, gender and race were evaluated. All the cleft and palate patients had similar treatment histories. Radiographic clichés were obtained from both groups and the images were traced after identifying the anatomic landmarks. The studied landmarks included points, lines, and plans as well as dental and skeletal angles and distance ratios measured in radiographic images. The landmarks were statistically analyzed using Student t test.

Results: Significant differences were found between the cleft lip and palate patients and normal individuals regarding craniofacial complex morphology (P<0.001). Gender did not show significant effect on the cephalometic indices changes (except to IMPA and FMIA angles). Tweed angle changes were more in the males than that of females between normal and cleft lip and palate patients. Mandibular retrusion (decreased SNB), gonial angle opening, increased mandibular plan inclination and facial anterior height were similar in the normal and cleft lip and palate individuals while no significant differences were found between two groups regarding cranium indices (P>0.05).

Conclusion: In total, significant differences were observed between normal and cleft lip and palate individuals regarding Tweed diagnostic triangle area. These differences were decreased IMPA and increased FMA and FMIA angles. No significant differences were found in terms of other indices.

Background and Aims: Bacteria and their products have a major role in pulp and periapical diseases. The purpose of this study was to compare the antimicrobial activity of sodium hypochlorite, iodide potassium iodide and chlorhexidine on the enterococcus faecalis after root canal filling.

Materials and Methods: In this experimental study, 95 single canal human teeth were collected. Then after washing and cleaning and filing, the sterilization done using an autoclave. The teeth were smeared with enterococcus faecalis except five which selected as controls and then divided them into 3 groups which A randomly represented the irrigation by sodium hypochlorite, iodide potassium iodide (IKI) and chlorhexidine solution were done. The teeth were filled with gutta-percha and then incubated in a incubator for 90 days at a temperature of 37° C. The specimens were analyzed for Colony Count. Data were analyzed using Kruskal-Wallis test and Chi-Square.

Results: According to the results of this study, the correlation between the 3 groups of cultured teeth were not significant (P=0.812).The specimens which were washed by IKI had the most positive amount of cultures (23.3%) and the specimens which washed by chlorhexidine had the lowest (16.7%).

Conclusion: The results of this study showed that after the use of different wash solutions, no statistically significant difference exist in their antimicrobial activity after root canal therapy.

Background and Aims: According to concerns of technical errors in intraoral radiographs and reports of positive effects of central ray laser pointer on the students, technical errors and shortcomings of earlier research, this study was conducted at Department of Oral and Maxillofacial Radiology of Tehran Azad University to determine the role and use of laser pointer in the technical error made by students.

Materials and Methods: This clinical trials study was carried out at the Department of Radiology, Dental School of Azad Tehran University. A total of eighty students were divided into two groups of forty. In the first group the periapical technique was taught without laser guided indicator, while in the second group laser guided indicator was applied in training the students. All students took X-rays from the phantoms. Laser guided indicator is made of one low power red laser diodes.Totally 560 X-rays were taken and the technical errors and the quality of X-rays were evaluated. Data were analyzed statistically using Mann-Whitney and Chi Square tests (&alpha=0.05).

Results: The X-rays taken by students showed significant differences in cone cutting (P<0.001), and overlapping (P<0.001) between the two study groups. In the subjective review of X-ray quality, the difference was also significant (P=0.03).

Conclusion: The use of laser guided indicator as a training aid seems to be practical for easier learning of central ray adjustment and reduction of technical errors in taking X-rays by dental students.

Background and Aims: Inadequate root canal obstruction has been suggested as major factor in endodontic treatment failure. On the other hand, the most common way to assess leakage is dye penetration method. In assessing the possible effect of cutting direction on the leakage, the present study was performed to investigate dye penetration in two root cutting directions.

Materials and Methods: Forty human teeth with a single root canal were used in this experimental study. Endodontic treatment was performed on the specimens and then stained with 2% methylene blue solution. The specimens were divided into two groups. Specimens in the first group were sectioned in the buccolingual dimension and the second group in the mesiodistal to evaluate the microleakage. The amount of dye penetration was measured under the stereomicroscope with a magnification of 40%. Data were statistically analyzed using Kolmogorov-Smirnov (KS) and Mann- Whitney tests.

Results: The average amount of leakage in the buccolingual and mesiodistal dimension were, 3.78±2.08 and 2.43±1.55 mm, respectively. There was statistically significant difference between the mean leakage of two dimensions (P=0.03).

Conclusion: Since the leakages in the buccolingual and mesiodistal dimensions were different, it was concluded that cutting direction could be an effective factor on the result of microleakage assessment.

Background and Aims: The purpose of the present study was to investigate the relationship between study skills and academic performance of dental students in Tehran University of Medical Sciences.

Materials and Methods: 195 dental students at dental faculty of Tehran University of Medical Sciences in 2013 participated in this descriptive-analytical study. Data were collected using Congos´ Study Skills Inventory including six subscales. Grade Point Average (GPA) indicated their academic performance. Data were analyzed using ANOVA and Tukey test.

Results: The mean score of students’ study skills were 108 out of 200 with standard deviation of 22.06±0.7. Note taking had a significant correlation with GPA (P=0.015).

Conclusion: Since no significant correlation between study skills and academic performance of the students was observed, it seems that there are other dynamics involved in their academic performance which have to be examined.

Background and Aims: Choosing an appropriate style of teaching-learning by educators is a way to reach high quality education. The objective of this study conducted in Babol Dental School was to compare dental students^, satisfaction of teaching theoretical general pathology course by means of a combination of lecture and work in small groups with their satisfaction of teaching the course by means of only lecture.

Materials and Methods: This study was performed in the second semester of school year 2011-12 and 2012-13. In 2012 (intervention group, response rate=92%), the teaching of theoretical general pathology course was implemented by means of a combination of lecture and work in small groups, but in 2013 (control group, response rate=81%) by means of only lecture. An anonymous self-administered questionnaire was used to assess students^, satisfaction of the teaching methods. To compare the mean total score of satisfaction (ranging from 18 through 90) between the two groups, T-test was used.

Results: Comparing the mean total scores between the two groups revealed that students^, satisfaction of the combined teaching method was significantly higher (P<0.001). The difference of satisfaction between genders (separately for each group) was not significant in combination group and lecture group (P=0.63 and P=0.87,   respectively).

Conclusion: Regarding learning, combining lecture with other teaching methods such as work in small groups may increase health sciences students' satisfaction. In regard to teaching theoretical general pathology course, our findings could confirm this hypothesis.

Background and Aims: Preserving intact coronal and radicular tooth structure is considered to be crucial for the optimal biomechanical behavior of restored teeth .The ferrule effect has been extensively studied and still remains controversial from many perspectives. The purpose of this study was to summarize the results of different issues related to the ferrule effect and published in journals listed in Pub Med.

Materials and Methods: The search was conducted from 1985-2014 from Pub Med and scientific dentistry internal journals using the following key words: Ferrule, Ferrule effect, Literature review, Fracture resistance, Fatigue, Finite element analysis.

Results: The finding showed that the presence of 1.5-2 mm high and 1mm thickness ferrule had a positive effect on the fracture resistance of endodontically treated teeth.

Conclusion: The presence of ferrule effect is essential for successful endodontic treatment. If a ferrule can performed, the teeth will have poor prognosis for survival.

Background and Aims: The presence of microbes inside the canal is the main reason for post-treatment infection. Therefore, the maintenance of the disinfection obtained during the treatment is imperative. The aim of this study was to compare the antimicrobial effect of Tricresol formalin and 5.25% Sodium hypochlorite on the Enterococcus faecalis.

Materials and Methods: In this study 66 human single-rooted extracted teeth were used. After access cavity and root canal preparation, the teeth were sterilized in autoclave, and then contaminated with Enterococcus faecalis suspension and incubated at 37°C for 7 days. Then, they were randomly divided into three groups of 20: In group 1, Tricresol formalin was used as intracanal medicament. In group 2, 5.25% Sodium hypochlorite and in group 3 (control group), normal saline were used as irrigants. 7 days after incubation at 37°C, the microbiological sampling was performed. For this purpose, dentinal shaves were collected from the root canals and cultured in Tryptic Soy Broth, and the number of Colony-Forming Unit (CFU) was counted. Data were analyzed using Kruskal-Wallis and Mann-Whitney tests.

Results: A significant reduction of CFU was observed in the Tricresol formalin and Sodium hypochlorite groups compared to the control group (P<0.001). No significant difference was reported between Tricresol formalin and Sodium hypochlorite groups (P=0.69).

Conclusion: The present study showed that the antimicrobial effect of Tricresol formalin was comparable with 5.25% Sodium hypochlorite on the Enterococcus faecalis.

Background and Aims: Microleakage is a criterion proposed for assessing the success of any restorative material. Complete seal is difficult especially for dentin margins compared to enamel margins. The aim of this study was to assess the microleakage at the enamel and dentin margins of class V cavities restored by two GIs and two self-etch adhesive systems.

Materials and Methods: This study was done on forty third molars. Class V cavities (3×2×2mm) were prepared on the buccal and lingual surfaces of teeth using high speed handpiece with 0.8 mm diamond fissure burr. The occlusal margins of the cavities in the enamel and gingival margins were placed 1 mm below the CEJ. The teeth were divided into 4 groups and the bondings were cured for 20 sec and the teeth were restored. The specimens were kept in distilled water at the temperature of 37°C for 24 hrs. The teeth were thermo cycled and cut in buccolingual direction using diamond disc under water. The dye penetration was evaluated using a stereomicroscope and the leakage was scored. The scores were compared using Kruskal-Wallis test while the paired comparisons were done using Bonferroni correction. P≤0.05 was regarded as significant results.

Results: Microleakage scores were similar at the occlusal and gingival walls of all test groups. At the gingival walls, the least microleakage scores were observed. “Fuji IX + SE bond” group showed significant differences with the “Fuji IX + G bond” and “Nanoglass + G bond” groups (P≤0.05). At the occlusal walls, the least scores were observed in the “Fuji IX+SE bond” specimens which were significantly different from the other groups (P≤0.05).

Conclusion: Self-Cure glass ionomers yielded less microleakage scores compared to the different types of light-cures due to the less polymerization shrinkage.

Background and Aims: As in fissure sealant therapy the tooth surface is mostly enamel, the use of an enamel bonding agent (hydrophobic bonding agent) may be more cost effective than that of newer generations of bonding (hydrophilic bonding agents). The aim of this study was to compare the retention and durability of fissure sealant therapy when applying an enamel bonding agent, a dentin bonding agent and no bonding agent during 4 years.

Materials and Methods: This study was done on the first permanent molars of the upper and lower jaws of 24 students of the first grade of a primary school (6-7 years old). On 36 teeth, a dentin bonding agent (Excite) was applied under the fissure sealant and on 36 teeth an enamel bonding agent (Margin bond) was applied under the fissure sealant. Then, 24 teeth were selected from these two groups and were compared with a group (including 24 teeth) with no bonding agent under the fissure sealant (as control group). All the fissures of the teeth were evaluated annually for 4 years to find out the presence or absence of fissure sealant substance. Data were analyzed using Wilcoxon test.

Results: From the statistical analysis, there was no significant difference in retention and durability of the fissure sealant substance comparing the group with dentin bonding agent (Excite) and the group with enamel bonding agent (Margin bond). Also, using a bonding agent made no significant difference (P>0.05).

Conclusion: According to the results of this study, using a bonding agent made no improvement in the retention and durability of fissure sealant substance.

Background and Aims: Elongation of styloid process may result in development of Eagle syndrome with associated symptoms. This study aimed to assess the frequency of elongated styloid process (ESP) and to evaluate its prevalence according to sex and age.

Materials and Methods: This study was conducted on digital panoramic radiographs of patients refered to the Oral Radiology Department of dental school, Guilan University of Medical Sciences. Styloid process length was measured and classified as elongated, pseudoarticulated, or segmented. Calcification patterns were determined as A, B, C, and D. ESP was defined as length > 30 mm. Data were analyzed by SPSS using T-test, Chi square, Pearson, and Spearman (P<0.05).

Results: A total of 505 digital panoramic radiographs taken from 227 males (45%) and 278 females (55%) aged 10 to 72 (40.1±12.9) years were evaluated. Elongated styloids were present in radiographs of 230 (45.5%) individuals. There was no significant difference in the ESP frequency between males (46.09%) and females (53.91%) (P=0.63). Type I and calcification B pattern showed more frequency than that of other categories.

Conclusion: According to these findings, elongated styloid process was a common condition among the studied population and had a significant correlation to the age.

Background and Aims: Dental erosion refers to the loss of tooth structure by being scratched chemically without bacterial involvement which needs to care about due to its prevalence and treatment problems. This study was designed with the aim of evaluation of the frequency of dental erosion and its causing factors in patients referring to yazd dental school in 2012-2013.

Materials and Methods: In this cross-sectional study, 400 patients referring to yazd dental school were randomly selected. All of their teeth were evaluated in three surfaces (buccal, lingual and occlusal). The BEWE score was used for classification the extent of damages. Also, patients were given a questionnaire that included patient demographic information and questions to investigate the causes of dental erosion. Data were analyzed using SPSS version 17 and Mann-Whiney, Fisher exact, and Chi-square tests.

Results: In this study, 138 men and 261 women were participated with the mean age of 33.26±10.83. 84 persons (21.1%) had erosion. There was a direct and significant relationship between the dental erosion and patient's age (P >0.001). Also, there was a direct relationship between the dental erosion and reflux and consumption of lemon and pickle, beverages, soft beer and juice (P>0.001).

Conclusion: Consumption of lemon and pickle, beverages, soft beer and juice increases the risk of erosion. Considering the prevalence of dental erosion in about 21% of patients, it is necessary to pay more attention to the knowledge of the causes of erosion and reduction strategies of it.

Background and Aims: Dental students’ evaluation of teachers’ educational activity is crucial for the improvement of dental school’s performance. The process of the evaluation needs a valid and reliable tool. This study aimed to produce and validate a questionnaire for the evaluation of dental school teachers by students.

Materials and Methods: A group of 15 teachers in the Shahid Beheshti dental school gave their opinions regarding the characteristics of an ideal teacher using nominal group technique. These characteristics together with characteristics gathered from similar studies made the base of a questionnaire which later underwent a validity and reliability assessment by means of the calculation of Content Validity Index (CVI), Content Validity Ratio (CVR), and Cronbach’s alpha coefficient.

Results: The preliminary questionnaire included 94 items in four categories naming: ethics, educational capability, practical capability, and managemet. After calculating CVR and CVI for each item, 23 items with CVR<0.33 and 20 items with CVI<0.79 have been excluded from the questionnaire leaving a questionnaire with 54 items. The overall reliability of this questionnaire using Chronbach’s alpha coefficient was 0.96.

Conclusion: Consulting an expert group that are familiar with different aspects of educational performance of faculty teachers, it was concluded that applying various methods for validity and reliability, and considering local culture values are useful for the preparation of the questionnaire for similar studies in Iran.

Background and Aims: Central odontogenic fibroma is a rare odontogenic neoplasm that originates from odontogenic ectomesenchyme. Most cases occur in the mandible and between the ages of 11 and 39 years. The neoplasm shows a definite female preponderance, with a ratio of 2.2:1 and has a very low recurrence rate. The aim of this article was to report a case of this rare lesion which was accidentaly found.

Case Report: A 11-year-old female, during her orthodontic treatment and without any complain and any sign or symptoms, performed a panoramic image for assessing the permanent teeth buds. In the panoramic view a unilocular radiolucent lesion with well-defined and corticated borders in the right mandibular body region was evident. The lesion was treated with simple excision. Simple type of central odontogenic fibroma histopathologic features was observed in the microscopic view.

Conclusion: Although the central odontogenic fibroma is a rare benign neoplasm, however, a careful evaluation of radiographic images is important for early detection of lesions because the patient may have no clinical symptoms such as swelling, pain and paresthesia.

Background and Aims: With the increasing use of CT (Computed Tomoghraphy) scans in dentistry especially in the implantology, there may be significant increases in the radiation exposure and its risk. During the last year’s ConeBeam Computed Tomoghraphy (CBCT) has been introduced as an imaging modality for dentistry. The aim of this review article was to present comprehensive information have been published, regarding the  radiation dose and image quality of Conventional Multislice Computed Tomography (MSCT), Cone-Beam CT (CBCT) and periapical radiography in dentistry imaging.

Materials and Methods: A review of the literature was carried out in PubMed, Google Scholar, Science Direct and Scopus database using key words (CBCT, MSCT, periapical radiography, radiation dose of dentistry and image quality). These searches were limited to the articles published between the years of 1993 to 2015.

Conclusion: In comparison to MSCT, CBCT had a short scanning times and lower radiation dose, but in comparison to periapical radiography, CBCT had higher radiation dose. In contrast, CBCT with flat panel detector had higher spatial resolution to MSCT. The periapical radiography also had a good image contrast and relatively high resolution. Generally, CBCT was suitable for hard tissue imaging and MSCT was preferred for soft tissue imaging.

Background and Aims: Microleakage is one of the most common problems in bonding systems, which cause different clinical shortcomings such as post operative sensitivity, marginal discoloration and pulp necrosis that can decrease those using bonding systems. The aim of this study was to compare the microleakage of three self etch bonding agents (generation 6 and 7) in class 5 composite cavities.

Materials and Methods: In this experimental study, 30 facial class 5 cavities were prepared in 30 human premolar teeth which were freshly extracted for orthodontic purposes. Cl V cavities were prepared in 2*3*2 mm dimensions. Occlusal margins were in enamel and gingival ones in cementum and randomly divided into 3 groups of 10 each. Then the cavities were treated by clearhil SE Bond (Kuraray, Japan), G Bond (GC, Japan), and Opti Bond Solo Plus (Kerr, USA), according to the manufacturers’ insductions. Then the cavities were filled using Z100 resin composite. The specimens were then immersed in a 50% AgNo solution for 24 hrs. Then, the teeth were cut buccolingually to be evaluated for dye penetration with stereomicroscope. Data were analyzed using Kruskal-Wallis test.

Results: This study revealed that Opti bond solo plus had type1 microleakage (dye penetration up to 1/3 of cavity) in 80% of specimen, and type 4 microleakage (along axial wall) in 10%. Clearfil SE bond had no leakage in 50%, type1 in 40% and type 2 (up to 2/3 of cavity) in 10%. But there was no significant difference in the microleakage at the gingival margins between 3 groups (P>0.05).

Conclusion: Clearfil SE Bond and G bond could prevent microleakage more effectively than that of Opti Bond Solo Plus on the occlusal margins. However, no difference in the microleakage on the gingival surfaces was found.

Background and Aims: In response to esthetic demand and use of zirconia abutments; detection of implant-abutment connection misfit is so important. The purpose of this study was to evaluate the sensitivity and specificity of radiographic images in the detection of abutment-implant connection misfit in zirconia and titanium abutments of three different implant connections.

Materials and Methods: One regular implant fixture of Branemark, Noble active and Replace systems were mount in acrylic models. Two pieces titanium and zirconium abutments were attached to the implants, once with correct adaptation and once with 0.5 mm spacer. Digital radiographic images were taken of 12 created states with zero degree vertical and horizontal inclination and evaluated by 10 specialists in implant treatment in two different time penods. Data were analyzed using Kappa analysis.

Results: Interclass Correlation Coefficients (ICC) of the agreement of answers in the first and second times were 97.4 and 97.5, respectively (P<0/001). Sensitivity of detecting gap in all groups was acceptable (95-100%) except titanium abutment in Noble active which was the lowest value (35%). Specificity of all groups were acceptable (80-95%) except zirconia abutments in Noble active and Replace with 45% and 30% values, respectively, and titanium abutments in Branemark had the highest value (95%).

Conclusion: The sensitivity of radiographic images in detection of abutment-implant connection misfit only in Noble active with titanium abutment was not acceptable. Specificity of radiographic images in the absence of gap in titanium abutments was more favorable.