JOURNAL OF ISFAHAN DENTAL SCHOOL
Year:2012 | Volume:7 | Issue:4|Papers Count:16

Introduction: The main factor involved in the failure of endodontic ally treated teeth is crown reconstruction rather than root canal treatment itself. The present study compared stress distribution in pre-fabricated and cast post-and-cores by finite element analysis. In addition, the effect of post material was evaluated.Materials and Methods: In this cross-sectional descriptive-analytical study, an extracted sound human mandibular second molar was embedded in an acrylic resin cylindrical mold. Axial crosssections were prepared by abrasion and photographed; the images were transferred into a computer software program and a three-dimensional solid model of the tooth was prepared. A load of 10.43 MPa was applied on a 23-mm2 surface area of the occlusal surface at an angle of 45o. Finally, different restoration models for pre-fabricated and cast posts were designed and the effect of post material was analyzed.Results: Cast posts generated less stresses compared to pre-fabricated posts; however, prefabricated posts were more conservative form the stress location viewpoint. Regarding stress concentration, gold posts were more favorable in comparison to titanium posts because stress concentration in gold posts takes place in the cervical region, so that if root failure occurs, reconstruction is possible.Conclusion: Cast posts result in less stress in roots compared to pre-fabricated posts. Except for gold cast posts, all other cast posts are more dangerous in relation to stress distribution.

Introduction: Fractures of acrylic resin dentures are quite common. It is favorable to securely repair the denture to prevent re-fracture. The aim of this study was to evaluate the flexural strength of heatcured acrylic resin samples repaired with Iranian and foreign self-curing acrylic resins alone and impregnated with uni-directional fiberglass.Materials and Methods: In this experimental study 40 specimens with a dimension of 65x10x2.5 mm were fabricated from Meliodent heat-cured acrylic resin. Eight specimens were left intact as the control group. The other specimens were first fractured and then 8 specimens were repaired with selfcuring Acropars acrylic resin; 8 specimens were repaired with self-curing Acropars acrylic resin impregnated with fiberglass; 8 specimens were repaired with self-curing Meliodent acrylic resin and finally, 8 specimens were repaired with self-curing Meliodent acrylic resin impregnated with fiberglass. Then the flexural strengths of repaired and intact specimens were measured by DARTEC machine. The results were analyzed with one-way ANOVA, and Tukey and two-sided Dunett tests (a<0.05).Results: An increase in the flexural strengths was observed only in Meliodent groups repaired with self-curing acrylic resin without fiberglass and with fiberglass (p value<0.008), with no significant differences between other groups (p value>0.05).Conclusion: Based on the results of the present study, the use of Acropars and Meliodent selfcuring acrylic resin impregnated with fiberglass in repaired site increased the flexural strength only in self-curing Meliodent group.

Introduction: Based on recent research, cytokines particularly IL-1a, IL-10, and INF-a might play a role in the pathogenesis of pemphigus vulgaris. Some autoimmune diseases have been successfully treated with the use of antibodies against cytokines. The aim of this study was to compare salivary concentrations of IL-1a, IL-10, and TNF-a in patients with pemphigus vulgaris and normal individuals.Materials and Methods: In this analytical-descriptive study, 24 pemphigus vulgaris patients referring to the Department of Dermatology, Alzahra Hospital, and 26 healthy individuals were evaluated. Unstimulated salivary samples were collected by spitting method in both groups. IL-1a, IL-10, and TNF-a concentrations were measured by ELISA technique. The results were analyzed by t-test (a=0.05).Results: The mean salivary concentrations of IL-1a, IL-10 and TNF-a were higher in pemphigus vulgaris patients compared to healthy subjects. The differences were significant in relation to IL-1α (p value=0.024) and TNF-a (p value=0.005) between the two groups; however, the differences were not significant in relation to IL-10 (p value=0.243).Conclusion: The increase in salivary concentrations of IL-1a and TNF-a in patients with pemphigus vulgaris compared to healthy individuals might indicate the role of these agents in the pathogenesis of this disorder.

Introduction: Attention to the location and the shape of mandibular canal is necessary to prevent problems during mandibular surgeries. This study was determined the prevalence of superior-inferior position of mandibular canal and its anatomic variations on panoramic radiographs in patients over 18 referring to Khorasgan Dental School.Materials and Methods: In this descriptive-analytical study 260 radiographs were examined for variations in the position of mandibular canal. The subjects’ personal data, type of mandibular canal regarding its position based on Nortje‘s classification (high, low or intermediate position in relation to the apex of the first molar root and inferior border of the mandible), the distance from the superior border of lingula to the center of the ramus, existence of bifid canal and its shape and side and existence of anesthesia problems or impacted teeth on the same side as the bifid canal, were recorded.Data was analyzed by SPSS 10, using chi-squared test (a=0.05).Results: The most common canals in relation to their position relative to the first molar area, in descending order, were canals in middle position (55.8%), in the low position (35%), and in the high position (9.2%), respectively. No statistically significant differences were observed between the frequency distributions of canal positions (p value=0.14%). The average distances from the superior border of lingula to the center of the ramus, in low position, middle position, and high position canals were 10.7, 11.35, and 10.87 mm, with no statistically significant differences (p value=0.14).Conclusion: According to the results, there were no statistically significant differences between the frequency distributions of different positions of mandibular canals in relation to the root apex of the first molar and also between the distances from the lingual to the center of the ramus. Similar studies using CT scan technique are recommended.

Introduction: Generally, the root canal walls become contaminated with MTA during MTA plug placement. On the other hand, the dentinal tubules need to be open for penetration of sealer. The aim of this study was to compare dentinal tubule contamination during MTA apexification between onevisit and two-visit appointments.Materials and Methods: In this in vitro experimental study, 38 single-canal human teeth, consisting of two groups of 17 and one control group of 4, were placed in 5.25% NaOCl for 30 minutes. The tooth crowns were removed at CEJ; then 2 mm of root ends were cut to create open-apex roots. Canal preparation and shaping were performed up to file #100 and Gates Gliden drill #4 using the stepback technique. The smear layer was removed using NaOCl and EDTA. Finally, the canals were dried. In groups one and two, MTA plug was condensed at root end at a thickness of 3 mm. In group one (one-visit), the samples were prepared for SEM immediately after cleaning the canal walls. In group two (two-visit), the samples were kept under 100% humidity at 37oC in an incubator for 24 hours. Then, the canals were irrigated with ultrasonic and 2.5% NaOCl and prepared for SEM. In the control group, only the smear layer was removed and the samples were prepared for SEM without MTA plug. Mann-Whitney and Kruskal-Wallis statistical tests were used for statistical analysis (a=0.05).Results: There was a significant difference between the groups in relation to contamination of the dentinal tubules with significantly more MTA on the canal walls in group one compared to group two (p value<0.001). The dentinal tubules were completely open in the control group.Conclusion: The results of this study showed that in apexification with MTA in open apex teeth, twovisit treatment sessions are superior to one-visit sessions.

Introduction: Gag reflex is one of the most common problems during dental procedures, especially during radiography and impression taking. The aim of this study was to evaluate the effect of Elaeagnus angustifolia drug film on gag reflex.Materials and Methods: One hundred patients referring to the Radiology Department of Isfahan School of Dentistry were selected for the purpose of this double-blind clinical trial and randomly divided into two groups. The gag reflex was provoked and then in 50 patients, medication A (placebo) and in 50 others medication B containing Elaeagnus angustifolia were placed for 3 minutes in zones which were trigger zones for the gag reflex. Then the patients’ gag reflex was evaluated again. Data was analyzed with Wilcoxon, Mann-Whitney and chi-squared tests (a=0.05).Results: In group A (placebo), frequency of distribution of gag reflex in the soft palate, tonsils and tongue were not significantly different before and after drug use. However, in group B, frequency of distribution of gag reflex exhibited significant differences in the tonsils (p value<0.001) and soft palate (p value<0.003) after drug application. In addition, there were no significant differences in sex distribution between the two groups.Conclusion: The results of the present study showed that a thin film of a medication containing Elaeagnus angustifolia has a positive effect on gag reflex in the tonsil and soft palate areas, and it can be used during dental procedures such as radiography procedures.

Introduction: Although leukoplakia is not associated with any pathologic diagnosis, it is considered a premalignant or precancerous lesion. Oral hairy leukoplakia (OHL) is one of the most common diseases which is induced by Epstein-Barr virus in immunocompromised patients, such as those with AIDS. The aim of this study was to evaluate presence of EBV in patients with common leukoplakia, hairy leukoplakia and healthy mucosa.Materials and Methods: In this retrospective case/control study, 18 samples of common leukoplakia, 12 OHL lesions and 30 samples of healthy mucosa (as controls) were selected from paraffin blocks of previous biopsies. DNA was isolated by chelex-100 method and PCR was carried out. Data was analyzed by chi-squared and Fisher’s exact tests using SPSS (a=0.05).Results: Ten samples of OHL (83%), 8 samples of common leukoplakia (44%) and 6 samples of healthy mucosa (20%) were EBV-positive. Fisher’s exact test showed that frequency distributions of EBV had significant differences between the groups and also between OHL and healthy mucosa (p value=0.001). Chi-Squared test revealed significant differences in the frequency distributions of EBV between common leukoplakia and OHL (p value=0.033). In comparison between common leukoplakia and healthy mucosa, frequency distributions of EBV did not exhibit significant differences (p value=0.071).Conclusion: Under the limitations of the present study, the frequency distributions of EBV in OHL were significantly higher than those in the two other groups, suggesting an important role of EBV in the pathogenesis of OHL and confirming the results of previous studies.

Introduction: Resistant microbial strains are major factors involved in root canal treatment failure.The aim of this study was to compare the antimicrobial properties of different concentrations of colchicine and calcium hydroxide.Materials and Methods: In this in vitro study, suspensions containing 5x105 colony-forming units of E. coli, E. faecalis, P. aeuroginosa, S. aureus, normal salivary flora and C. albicans and different concentrations (1, 0.5, 0.25, 0.125 and 0.0625 mg/mL) of calcium hydroxide and colchicine were prepared. The samples were incubated at 37oC for 24 hours. Then turbidity of the samples was evaluated to determine minimum inhibitory concentration (MIC). Then 0.1 mL of the broth with no turbidity was cultured on solid medium to determine minimum bactericidal concentration (MBC). In order to make sure of the accuracy of the process, positive, negative and standard controls were also prepared.Results: In evaluation of sample turbidity after 24 hours, all the tubes containing calcium hydroxide and positive controls showed complete turbidity. In tubes containing colchicine turbidity was found in all the bacterial categories. Only tubes containing Candida albicans with concentrations of 1, 0.5 and 0.25 mg/mL of colchicine were clear and lower concentrations showed turbidity. In evaluation of formation of colonies on Sab. Dextrose agar, only plates with 1 mg/mL of colchicine showed no growth.Conclusion: Only concentrations of 0.5 and 0.25 mg/mL of colchicine exhibited inhibitory effects and 1 mg/mL exhibited lethal effect on Candida albicans. None of the two drugs exhibited any inhibitory or lethal effects on other microbial strains.

Introduction: In recent years, proportions and harmony of orofacial soft tissues have gained great importance in orthodontics. The aim of this research was to evaluate soft tissue thickness changes of facial midline landmarks during growth in both genders.Materials and Methods: In this analytical-descriptive study, lateral cephalometric views of ninetyeight 6-18 year-old patients referring to the Orthodontics Department of Khorasegan Azad University were evaluated. The positions of 7 facial midline landmarks, including glabella, soft tissue nasion, soft tissue points A and B, soft tissue pogonion, and superior and inferior labrale, were determined and then the thicknesses of the landmarks were measured. Data was compared between two groups of under and above 12 years of age between males and females using independent t-test (a=0.05).Results: There were no statistically significant differences between the soft tissue thicknesses of both sexes in any of the landmarks except nasion (p value=0.026) and point B (p value=0.043) in the group under 12 years of age.Differences between the soft tissue thicknesses in both sexes over 12 years of age were statistically significant in nasion (p value=0.043), point A (p value=0.001), and superior labrale (p value<0.001). Differences between soft tissue thicknesses of all the landmarks were statistically significant between the two age groups in males except point B (p value=0.119); however, in females only the thickness of soft tissue nasion (p value=0.105) and superior labrale (p value=0.968) were not statistically significant between the two age groups.Conclusion: Soft tissue thicknesses were almost the same in boys and girls except nasion and point B before puberty. After puberty upper face soft tissue thicknesses, including glabella and point A, were greater in boys compared to girls. However, in both sexes, soft tissue thicknesses of facial midline landmarks increased after 12 years of age.

Introduction: A common procedure in esthetic dentistry is fabrication of metal-ceramic veneer crowns that have proper color match with the patient’s teeth. The aim of this study was to compare color reproduction of the selected color by dental practitioners in dental laboratories by technicians with and without academic education.Materials and Methods: In this in vitro study a maxillary incisor from a dental model was prepared for a metal-ceramic veneer crown. After impression taking and making a standard framework, 36 impressions were taken for 36 laboratories and two standard metal frameworks were fabricated on each die. Two frameworks were sent to each laboratory. A3 porcelain was requested to be placed on the standard frameworks and glazed. Each specimen was tested with Shadepilot equipment. a*, b* and L* color indexes andD E were determined at incisal, middle and cervical areas of each crown. Ttest and linear regression were used for data analysis (a=0.05).Results: Means and standard deviations of D E of samples in the group without academic education at incisal, middle, and cervical areas were 3.56±1.93, 2.54±2.40, and in 3.0±1.16, respectively; corresponding values in the group with academic education were 5.6±3.19, 2.11±1.02, and 21.18±0.72, respectively. T-test showed significant differences inD E of incisal areas between the two groups (p value=0.003), with no significant differences in other areas.Conclusion: In this study, there was a significant relationship between job experience and color match accuracy in the incisal region, indicating that technicians with more job, but with no academic education, exhibit more accuracy in reconstructing incisal edge color of metal-ceramic veneer crowns.

Introduction: Biphosphonates are used in the treatment of bone metastatic tumors and osteoporosis.The most adverse effect of bisphosphonates is osteonecrosis of jaws, which is difficult to control. The aim of this review was to evaluate articles published on the effect of these medications on jaws and methods to control and prevent its side effects in comparison with complications of radiotherapy in the head and neck region.Review Report: A Pubmed/Medline search was run using the key words biphosphonates, osteonecrosis and jaws from 1980 to 2010. Of the 160 articles in the search results 44 were case reports.Results: Osteonecrosis of the jaws, with signs and symptoms similar to osteoradionecrosis, is a complication of biphosponate use, especially when used intravenously. Oral use of these medications is not absolutely contraindicated in dentistry.Conclusion: The best way to treat jaw necrosis is its prevention. There is a low risk for the incidence of osteonecrosis during the first 6 months of treatment with biphosphonates. Use of chlorhexidine mouthwash might be useful in these patients.

Introduction: Polyphenpls are the most common antioxidants in foodstuffs, which have an important role in the prevention of chronic diseases. Periodontitis is a chronic disease of the supporting structures of teeth, which can destroy periodontal structures and result in tooth loss. The aim of this review article was to evaluate the effect of polyphenols on periodontal diseases.Review Report: All the relevant articles indexed in the Pubmed from 2002 to 2011 were surveyed.After studying the abstracts of 48 collected articles, 13 irrelevant ones were excluded and full texts of 35 remaining articles were assessed.Conclusion: Regarding the existing articles about polyphenols, it appears consumption of polyphenol-containing products may be effective in plaque control and prevention of periodontal diseases. Therefore, it is suggested that the results of in vitro studies be assessed by clinical trials.

Introduction: Taurodontism is a dental developmental anomaly, which is characterized by enlargement of pulp chamber and apical displacement of the pulpal floor. The incidence of taurodontism in white people is about 0.5-2.5%. Its prevalence in the Asian people is 3-30%, with the highest prevalence in the Mongolians and people of the East Asia. Taurodontism can occur alone or as a part of a syndrome, in which case the syndrome can be identified by dental practitioners because of the presence of taurodontism.Clinically, the crowns of these teeth are like other teeth, but enlargement of pulp chamber, lack of cervical constriction and short roots are visible on radiographs.Case Report: In this report one case of this anomaly is presented, which was bilateral in the radiographic examination.Endodontic treatment of tooth was indicated due to irreversible pulpitis. In this report, the root canal therapy of this case is presented.Conclusion: Although there are difficulties in the various steps of root canal treatment, successfulroot canal treatment of teeth with taurodontism is possible.