Journal of Dental Medicine
Year:2016 | Volume:28 | Issue:4|Papers Count:16

Background and Aims: Optimization drilling parameters in order to temperature decrease during creation of hole in the bone is an interested issue. The aim of this study was to achieve optimum values of drilling parameters based on the creation of minimum temperature during jawbone drilling.Materials and Methods: In this study two models of mandible and maxilla was created and teeth 2, 5 and 8 from maxilla and teeth 25, 28 and 31 from mandible were removed. The drilling operation was performed under different conditions on jawbone models using finite element analysis and the maximum temperatures were measured in adjacent of holes.Results: Drill bit head angle of 70 degrees was created the lowest maximum temperature during drilling operation. The lowest maximum temperatures were observed in the drill bit rotational speed, drill bit feed rate and the force exerted on the drill bit equal to 200 rpm, 120 mm/min and 60 N, respectively. The use of irrigation can decrease the maximum bone temperature about 7ºC. The maximum temperature differences in various regions of mandible and maxilla were approximately about 1ºC.Conclusion: Sharpness of drill bit head angle, reduction of drill bit rotational speed, increasing drill bit feed rate and exerted force on drill bit and also the use of irrigation played effective roles in temperature decrease during jawbone drilling. Drilling site did not have important effect on the temperature changes during jawbone drilling.

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: Considering importance of recognizing the position of incisive canal before inserting intraosseous implants and bone harvesting from the symphysis and to preventing from adverse effects after these surgeries, using appropriate imaging method is essential and necessary. Due to the high accuracy measurement and high quality of CBCT and also low received dose to patient ̦ the aim of this study was to evaluate and recognize the position of incisive canal using cone beam computed tomography (CBCT).Materials and Methods: In this study, good quality CBCT mandible image of 60 patients including 32 women and 28 men with average ages of 41.3±2.5 were observed for diagnosing and recognizing the position of mandibular incisive canal using three observers separately. Data were statistically analyzed using SPSS software (version 20.0 for Windows, Chicago, IL, USA) and Chi-square and Fisher’s exact tests.Results: Horizontal and vertical assessment was independent from the sex of patients. The incisive canal was recognizable in 89.8 percent of specimens. In vertical dimension, in 57.5 percent of specimens the canal was observed in the inferior one third and in 32.25 percent in the medial one third. In horizontal dimension, in 14.75 percent of specimens the canal was observed in the buccal one third, 52.75 percent in the medial one third and 22.25 percent in the lingual one third.Conclusion: The quality of CBCT imaging and its accuracy and resolution can play an important role in the differentiation and determination of the position of incisive canal.

Background and Aims: Micro leakage 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 micro leakage 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: Micro leakage scores were similar at the occlusal and gingival walls of all test groups. At the gingival walls, the least micro leakage scores were observed. “Fuji IX + SE bond” group showed significant differences with the “Fuji IX + G bond” and “Nano glass + 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 micro leakage 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, pseudo articulated, 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 Tomography) 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 Tomography (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.