Journal of Mashhad Dental School
Year:2013 | Volume:37 | Issue:2|Papers Count:14

Introduction: In the education system in the country, thesis works as a way to solve research problems and thesis presentation is based as part of the research. To improve the quality of dissertations, it is essential to have an accurate evaluation of the objectives, practical process, process and efficiency of the course by supervisors, graduates and students. The purpose of this study was evaluation of the view point of senior and graduated students and supervisor teachers of Mashhad dental school about thesis.Materials & Methods: Forty eight supervisors, 40 students and 50 graduates from Mashhad dental school participated in this cross sectional descriptive study in the year 2010. Three questionnaires, which proved to be valid and reliable, were used for data collection. Results were analyzed according to the frequency distribution of variable and average of description. Common questions were compared by Kruskal-Wallis test at a significance level of 95%.Results: The data indicated that the effect of thesis presentation on the activities leading to production and basic science and increase in professional knowledge and skills were average while it was very effective in teaching research methods. Students, graduates and supervisors together agreed on the completion of a joint research project in the early years of school and covering an education subject about thesis goals. Supervisors estimated the effect of thesis result in community to be more than that of the graduates (P=0.03). In addition, supervisors had less agreement on thesis as a voluntary course compared to students and graduates (P=0.01).Conclusion: Based on findings of this study, because of the great amount of budget and time spent on thesis, it is better to optimize the presented results and recommendations in this regard. It also seems that the greatest impact on improving the process would be created through revising the rules, creating supportive organizations actively and purposeful management of the issues and activities associated.

Introduction: The importance of quality assurance makes the standard compilation in educational systems as a high priority subject in medical education. The purpose of this study was to study the compilation of quality improvement standards in general dentistry program in Islamic Republic of Iran.Materials & Methods: This descriptive study was performed during the years of 2011 & 2012 in three phases. In the first phase, previous literature and similar standards were included in a comparative study and screened based on national health policies in Health map. Results were evaluated by 16 dental school representatives using modified Delphi methodology and open-closed questionnaires were filled by their faculty members and were reported back to the dental secretariat of ministry of health in the second phase. In the final phase, results were evaluated in the secretariat by a focus group and the final criteria were introduced based on the secretariat politics.Results: Fifty-eight criteria were created in the first phase. Data were collected from 13 faculties in the second phase (response rate=81%). Eighteen criteria had less than 90% agreement of the participants; however, all of the criteria were agreed by more than 70% of the participants. In the final phase, 48 quality improvement standards in seven areas were accepted and introduced in dental secretariat of the ministry of health.Conclusion: The final standard documents could be used as a national covenant of quality improvement based on their high agreement rate and dependence by national politics in the health map.

Introduction: The reliable bond at the root-post-core interface is critical for the clinical success of post-retained restorations. To decrease the risk of fracture, it is important to optimize the adhesion. Therefore, various post surface treatments have been proposed. The purpose of this study was to investigate the influence of various surface treatments of fiber posts on the bond strength to composite core.Materials & Methods: In this study, 40 fiber reinforced posts were used. After preparing and sectioning them, resulting specimens were divided into four groups (N=28). The posts received different surface treatments such as no surface treatment (control group), preparing with hydrogen peroxide 10%, preparing with silane, preparing with HF and silane). Then, posts were tested in micro tensile testing machine. The results were analyzed by One-Way ANOVA and Dunnett T3 test.Results: The greatest bond strength observed was in treatment with hydrogen peroxide 10% (19.84±8.95 MPa), and the lowest strength was related to the control group (12.44±3.40 MPa). The comparison of the groups with Dunnett T3 test showed that the differences between the groups was statistically significant (a=0.05).Conclusion: Based on the results of this study, preparing with H2O2 -10 % and silane increases the bond strength of FRC posts to the composite core more than the other methods. Generally, the bond strength of posts to the composite core increases by surface treatment.

Introduction: The antiseptic characteristic of root canal filling materials seems very critical in pulpectomy procedure to eliminate residual pathogens of root canals. The aim of this laboratory study was to compare the antibacterial activity of a newly introduced premixed calcium hydroxide root canal filling paste of deciduous teeth (Diapaste) with Zinc Oxide-Eugenol (ZOE) and Sealapex on Enterococcus faecalis.Materials & Methods: In this study, agar diffusion inhibitory test was used to assess antibacterial activity. Ten 10-cm-diameter dishes with 4.0mm thickness of agar inoculated with Enterococcus faecalis were used and four 5-mm-diameter wells per dish at equidistant points were filled with the three test root canal filling materials (Diapaste, ZOE and Sealapex) and distilled water as a negative control was used to fill the fourth well. After incubation of the plates at 37oC for 48 hours, the diameter of the zones of bacterial growth inhibition produced around the wells was measured (in mm) with a caliper. Data were analyzed by Kruskall-Wallis test and Mann-Whitney U test.Results: Kruskall-Wallis test indicated that there were statistically significant differences (P<0.001) among median of the zones of bacterial growth inhibition produced by the three different materials. Mean diameter of inhibition zones of bacterial growth was significantly higher in Diapaste than Sealapex (P<0.001) and ZOE (P<0.001).Conclusion: With respect to the limitations of an in vitro study, it appears that Diapaste has more antibacterial activity than ZOE and Sealapex.

Introduction: Lesions with formation of bone and/or cartilage are a group of osseous lesions in the jaws including a group of non-neoplastic lesions as well as benign or malignant neoplasm. A group of these lesions are known as fibro-osseous lesions. The purpose of this study was evaluation of clinical and histopathologic characteristics of non odontogenics lesions of the jaws with formation of bone or cartilage in referral patients to Mashhad dental school during 40 years.Materials & Methods: In this study, a review was made of all the biopsies in the histologic dept, of mashhad dental school between 1970 and 2010. Every patient with diagnosis of non odontognic lesion with formation of bone or cartilage was brought into account. Individual informations including gender, age, and region of the lesion, clinical and histologic findings were noted. These data were defined descriptively and were compared by Chi-Square test.Results: A total of 9991 biopsies were reviewed during this study period. Out of these, 133 cases (%1.33) corresponded to non odontogenic lesions with formation of bone or cartilage.Ossifying fibroma with 37 cases (28%) was the most frequent lesion followed by osteosarcoma with 19 cases (14%). The mean age of the patients was 32.2±17.3 years, with minimum age of 9 years and maximum of 75 yrs. In age distribution between different decades of life, most of the lesions were seen in second decade of life with 36 cases. Most of the patients were females with 79 cases whereas males were 54 cases.Conclusion: This study shows that non odontogenic lesions with formation of bone or cartilage have low frequency compared to other lesions of the jaws. Among studied lesions, ossifying fibroma followed by osteosarcoma were the most frequent lesions. Females were more involved than males and most of the lesions occurred in mandible and in posterior area.

Introduction: Despite high strength of pure Zirconia, it is too white to achieve all esthetic treatment needs in some patients. It seems that adding color agent affects the mechanical properties of Zirconia and its fracture strength. The objective of the current study was to compare the fracture strength of Zirkonzahn ceramics using colors A3, B3, D3 and the one without coloring.Materials & Methods: In the current study, disc-shaped Zirkonzahn specimens were fabricated using standard principles with the dimensions of 1´15 mm and randomly colored using A3, B3 and D3 shades (10 specimens for each group). Furthermore, 10 uncolored specimens were also considered as control group. The fracture strength of the specimens was measured using biaxial flexural strength method and piston-on-3-balls test. The elements in the specimens were determined by EDX (Energy Dispersive XRay) examinations. The data relevant to flexural strength were subjected to one-way ANOVA test.Results: Flexural strength of uncolored Zirkonzahn specimens was 1449.61 MPa. These values were found to be 1660.72MPa, 1624.28 MPa and 1496.38 MPa in the specimens colored by A3, B3 and D3 shades respectively. No significant differences were found among different groups regarding the mean of fracture strength.Conclusion: It seems that flexural strength of Zirkonzahn was not influenced by coloring factor or the kind of colors used.

Introduction: The purpose of this study was to assess orthodontic treatment needs of 14-18 year-old male students of Isfahan public schools which were carried out in 2009-2010 via Index of Orthodontic Treatment Need (IOTN).Materials & Methods: The study sample comprised 408 14-18 year-old male students selected by random clustering method. The subjects were examined clinically via IOTN which has two components: Dental Health Component (DHC) and Aesthetic Component (AC). Data were analyzed by chi-square test (a=0.05).Results: Regarding DHC, 4.4% of samples had very severe need (DHC5), 16.2% had severe need (DHC4), 22.5% had moderate need (DHC3), and 56.9% had minimum or no need (DHC1, 2) to Orthodontic treatment. In those showing grade 5, the most common malocclusion was unerupted teeth (i). The most common malocclusion in grade 4 was hypodontia (h) and in grade 3 was; overjet less than 4 mm and more than 2 mm (a). The most common malocclusion in grade 2 was contact displacement (d) less than 2 and more than 1 mm. In addition, regarding AC, 76.5% of the subjects were classified as “no need”, 15.2% as “borderline need” and 8.4% as “definite need” for treatment.Conclusion: 20.6% of 14-18 year-old male students in Isfahan needed orthodontic treatment (IOTN grades 4 and 5).

Introduction: fluoride application and fissure sealant therapy have an important cariostatic effect in pediatric dentistry. Investigations are indicative for effects of topical fluoride specially APF (Acidulated Phosphate Fluoride) gel on the restorative materials. The purpose of this study was to assess the effect of repeated application of APF (1.23%) gel on the surface roughness of two fissure sealants and one flowable composite.Materials & Methods: In this experimental study, 81 specimens of two fissure sealants and one flowable composite were prepared, using special polymer mold in three groups of 27 including: unfilled resin sealant (Fissurite F, Voco), filled resin sealant (Fissurit FX, Voco) and one flowable composite (Arabesk Flow, Voco). Then, these three groups were divided into three sub groups of 9 as follows: Group 1, 4, 7 (control): No treatment. Group 2, 5, 8: Single application of APF gel. Group 3, 6, 9: Six times application of APF gel. The APF gel was applied on the surface of specimens each time for 4 minutes. Then, the specimens were stored in the distilled water. Finally, the surface roughness of the sealants was measured by Profilometer. The statistical analysis was performed by 2-Way ANOVA & One-Way ANOVA.Results: The results of the study showed a significant statistical different between the surface roughness according to the type of material (P<0.001). Unfilled fissure sealant, showed maximum surface roughness and flowable composite showed minimum surface roughness. Also, the frequency of APF gel application (once or many times), had no effect on the average surface roughness of the materials (P>0.05).Conclusion: All three materials were resistant to the destructive effects of APF gel and no significant surface roughness was detected on them.

Introduction: In spite of numerous developments in resin composites products, their color stability is still a major problem particularly in pediatric dentistry, since frequent visits of children is of great importantance due to their behavior management, regardless of the problems pertaining to aesthetic and additional expenses. The purpose of this study was to evaluate the effect of common children drinks on the color stability of nanohybrid and microhybrid resin composites.Materials & Methods: In this experimental study, 80 disk samples (with diameter of 10 mm and depth of 2 mm) of microhybrid (point4 Kerr) and nanohybrid (Herculite XRV Ultra Kerr) resin composites were prepared. (categorized in 2 groups of 40).Then the samples of each group were divided into five subgroups of eight and were immersed in five different solutions (orange juice, red grape juice, fanta coke, chocolate milk) and distilled water as the control group for 4 hours daily for a period of 10 days. The color of samples was measured by a spectrophotometer at the beginning of the study and after staining using CIE lab system. The data were analysed by 2-Way ANOVA test.Results: 2-Way ANOVA showed that there was no significant statistical difference between the microhybrid (P4) and nanohybrid (HCU) resin composites with respect to the degree of staining in the mentioned solutions (P=0.29). Moreover 2-way ANOVA showed that type of the drink has a significant effect on the degree of staining of materials (P<0.001).Conclusions: It doesn’t seem that the new Nano composites have any considerable advantage to microhybrid resin composites regarding staining. Also regarding these results, colored drinks especially red grape juice and chocolate milk are not recommended in the first days after composite filling.

Introduction: Malignent Fibrous Histiocytoma (MFH) is the most frequent soft tissue sarcoma of adulthood. The most common sites affected by MFH are limbs, orbit, retroperitoneum, pelvis and knee. Oral cavity and mandible involvements are very rare.Case Report: A 35-year-old male was visited in the oral medicine department of Hamadan dental school with the chief complaint of pain and teeth mobility. The patient also had a history of paresthesia in lower lip for two monthes. In intraoral examination, there was a crater like, deep and disseminated ulcer in lower buccal and ligual gingiva of right mandibular teeth and exophitic lesion with smooth surface, and color similar to normal mucosa with 2´2´3 cm in diameter in buccal and lingual part of right lateral and central teeth extended to left second premolar was observed. Gingival resorption was observed in all adjascent teeth. There was radiolucency with irregular border in all part of lesion. MFH was confirmed by histopathological report.Conclusion: The most common complaint of patients with malignant fibrous histiocytoma is the growing mass that could be ulcerative or painful. Early diagnosis and referral is very important in prognosis and survival of the patients.