مجله تحقیق در علوم دندانپزشکی
سال دهم شماره 1 (پیاپی 35، بهار 1392)

Prevention of ridge collapse following extraction of maxillary anterior teeth is imperative for esthetic and functional restorative results. Several regenerative techniques are available and are used for socket preservation. The aim of this study was to assess extraction socket healing and alveolar ridge alteration after socket augmentation using bone allograft covered with dense polytetrafluoroethylene (dPTFE) membrane compared to free gingival graft (FGG). Twenty non-smoking healthy subjects were selected for this blind randomized clinical trial. Horizontal and vertical alveolar ridge and socket depth dimensions were determined، immediately after tooth extraction. The samples were randomly divided into two groups in which the extraction sites were filled with either a partial demineralized bone allograft that was covered with dPTFE membrane or FGG. Final measurements were taken after 4 months at which time، implants were also placed in. Trephine core biopsies were harvested for histological analysis prior to implant placement. Paired t test and t-test were used for statistical analysis. The alveolar ridge width in dPTFE group was 8. 31±1. 41 mm prior to the insertion of implants and 5. 30±1. 86 mm after the implant placement (P=0. 006). These measurement were 7. 63±1. 54 and 4. 88±1. 87 mm in FGG group prior and after the implant placement. (P =0. 000) There was a greater reduction in bucco-linguel width of the ridge in dPTFE group compared to FGG group. However، the difference was not statistically significant. (P=0. 6) The bone regeneration and resorption were similar in the two group and no statistically significant different was seen. (P=0. 2)، (P=0. 3) There is no different between the two treatment modalities in terms of bone resorption and regeneration. Both dPTFE and FGG techniques indicate similar effects in socket bone preservation in a 4 month follow up.

Different types of brackets are manufactured by various companies which are used in orthodontic treatment. The amounts of nickel، chromium and cobalt ions nreleased from these brackets are different and the side effects of these ions are clearly known. The purpose of this study is to assess the effect of time on the release of ions from various brackets that are manufactured by 4 companies. In this experimental study 160 orthodontic brackets from Biom،Organizer،American and Dentarum companies were evaluated for ion release. The samples were divided into 8 groups containing 20 brackets each. Four groups were immersed in artifact saliva and kept in an incubator for one week. The other four groups were immersed in artifact saliva for 6 months. Afterwards، 0. 5 ml of each solution was analyzed by spectrophotometer for the the amount of released Cr،Co and Ni ions. Statistical analysis of the data was done using one way ANOVA، two way ANOVA، Tomhane and t test. The level of Ni،Cr and Co ions released for different brackets after one week were as follows: Biom: 378±16. 5، 0. 4±0. 74،0. 4±0. 1. Dentarum: 142±10. 12، 2. 61±0. 22، 1. 34±0. 14. American: 58. 5±2. 06، 0. 46±0. 28، 0. 65±0. 04. Organizer: 57±3. 53، 0. 22±0. 47، 8. 9±0. 3، the ions released after a period of 6 months reported to be as follows: Biom: 3000±91. 4،2. 4±0. 12،4000±0. 38. Dentarum: 1200±87. 23،3. 40±0. 21،2. 40±0. 08. American: 55. 1±2. 21، 3. 2±0. 07،11. 40±0. 16 Organizer: 55. 20±2. 32،7. 80±0. 22، 6. 50±0. 11. The amount of released ions was found to be significantly different among the four groups. (p<0. 001) The American brand released the least amount of ions in the long term. Therefore، it is a more suitable choice for long-term orthodontic treatments.

Dimensional changes of Alginate due to late pouring of the impression material is not only a concern but a significant indication for manufacturing long-extended Alginate impression materials. The aim of this research was to assess the effect of time on the dimensional changes of Hydrogam-5 Alginate. In this experimental study، a model was prepared from which، 15 impressions were taken using Hydrogam-5 Alginate. The samples were divided into three groups which were stored in sealed plastic bags for a period of 30min، 24hrs، and 120hrs. (Iso 1563:1990 E) Afterwards، the impressions were poured with improved stones. The large and small diameters as well as the distance and height between the dies were measured by profilometer microscope and data was analyzed by Kruskal Wallis statistical method. The percent of dimensional changes in large and small diameters، the height of the large die، as well as the distance between the dies in sample groups after 30min، 24hrs، and 120hrs were: (0. 7، 0. 5،0. 2،0. 6)، (0. 6، 1. 3، 1. 1، 0. 4) and (1. 2، 0. 3، 0. 3، 0. 3) percent respectively. The difference was not significant (p<0/1). The time elapsed did not cause dimensional changes in the Hydrogam-5 Alginate، however the extent of changes were more than the claim of its manufactures.

Discoloration of dental composite resins is one of the most common reasons for replacement of composite restorations which may cause patient dissatisfaction and additional time and expenses for replacement. Tea is the most common drink among Iranians which is largely responsible for discoloration of composite restorations. The purpose of this study was to evaluate the effect of two types of tea (Iranian and imported) on discoloration of two commonly used microhybrid composite resins (FiltekZ250 and Point4). This experimental and invitro study was done on 30 specimens made from two composites FiltekZ250 and Point 4. The primary color measurement was done with spectrophotometer before immersing the samples in separate mediums. The specimens from each type of composites were randomly divided into three groups، each of which was then immersed in a different medium (Iranian tea، imported tea and distilled water). While immersed in the prepared mediums، the samples were stored in a 37˚c incubator for one week، after which time، the final color measurements were taken. Results were statistically analyzed with one way ANOVA test. When exposed to the medium containing imported tea، the reported color changes in FiltekZ250 and Point 4 composites were measured to be: 11. 84±1. 71، 12. 29±4. 10 and when exposed to the Iranian tea it was reported: 7. 87±0. 85،5. 98±2. 12. Both composite resins showed a significant color changes (P<0. 001) which was not clinically acceptable (ΔE>3. 3). The two composites did not show any significant difference in discoloration rate. (P>0. 05) Both micro-hybrid composites (Filtek Z250،Point4) demonstrated color changes which were clinically unacceptable. The imported tea caused more discoloration compared to the Iranian one.

Diverse teaching strategies have an imperative impact on learning process. The purpose of this study was to compare the effects of practical-theoretical vs. theoretical-practical based teaching methods on learning process of dental anatomy and student''s satisfaction in general. A randomized controlled clinical trial cross over study was performed on 72 second-year dental students. The students were randomly divided into two experimental groups (A and B). In the first phase، anatomy of the maxillary central incisors was presented to group A by theoretical-practical method (control group) and to group B by practical-theoretical method (experimental group). In the second phase، anatomy of the mandibular central incisors was presented and the two group were switched. The learning adequacy in each group was assessed by a standard test at the end. The data was analyzed by Mann-U-Whitney test. Total of 72 second-year dental students were assessed، Mean age was (21. 2±1. 5) and %68 of them were female and %32 were male. Reported scores in practical-theoretical teaching method was 16. 8±0. 8 and in theoretical-practical teaching method was 15. 2±0. 9. This difference was statistically significant (p<0. 01). The score for student''s satisfaction in practical- theoretical teaching method was 4. 4±0. 6 and for theoretical-practical teaching method was 3. 3±0. 8. This difference was statistically significant. (p<0. 001) The practical-theoretical method of instruction appears to be more effective than the traditional lecture based education. Furthermore، higher students’ satisfaction is reported with this means of education.

Determination of the exact location of the inferior border of nasal cavity is a fundamental element in precise surgical procedures such as implant placements. The purpose of this study is to compare the accuracy of the digital periapical، panoramic & CBCT images in linear measurements of the distance between the inferior of nasal cavity and alveolar crest. A descriptive study was conducted on three dry skulls in which seven locations، 5mm apart from one another، were marked by Gutta-Percha from canine to canine (total: 21 location). Digital periapical radiographies using parallel technique، digital panoramic and CBCT images were obtained and vertical dimensions from alveolar crest to inferior border of nasal cavity (marked areas) were measured. These measurements were then obtained directly from the dry skulls using digital caliper as our gold standard (with an accuracy of 0. 1 mm). Data analysis and comparison between the groups were done using repeated measurement Anova test. The mean error for periapical radiography was o. 13±0. 12 mm، 0. 35±0. 25 mm for CBCT and 1. 15±0. 61mm for panoramic. In digital periapical radiography (100 %) of measurements، in CBCT 70% and 17. 5% in Panoramic radiography were acceptable (in within the range of ± 0. 5 mm). According to the LSD test there was a statistically significant different between radiographic techniques. There was significant statistical differences between the three radiographic modalities in terms of adequacy of measurement. (p<0. 05) Digital parallel Periapicals are more accurate than panoramic and CBCT images in determining the linear measurement between the inferior border of nasal cavity and the alveolar crest.

Saliva levels of IL-4 and IFN gamma have been reported to show discrepancies in patients with Oral Lichen Planus (OLP). The purpose of this study was to assess the saliva levels of these markers with the aim to facilitate the diagnosis and understanding of the pathogenesis of Lichen Planus. This Case-control study was conducted on 84 samples consisting 30 patients with (OLP) and 54 healthy samples who showed no mucosal lesions on clinical examination. The saliva specimens were analyzed by ELIZA test for evaluation of IL4 And IFN γ levels. Data were analyzed by Mann-U-Whitney test، Spearman and Pearson coefficient tests. The saliva levels of IFN-gamma in samples with Lichen Planus was 4. 48 + 4. 3 compared to 3. 54 + 2. 7 in healthy samples. The IL-4 alevels were found to be 3. 28 +11. 07 in patients with Lichen Planus whereas in healthy subjects it was reported to be 2. 86 + 6. 3. No significant differences were found between the levels of IFN gamma and IL-4 in patients with (OLP) compared to control group. (P = 0. 8) (P = 0. 06) There is not any differences between reticular and erosive form of OLP in IL-4 and IFN γ levels. (P = 0. 2) Our findings indicate that these two factors are not involved in pathogenesis of lichen planus، however but more studies. are recommended.

Views regarding work ethics and Professional attitude are highly controversial in the field of medicine. Different approaches towards work ethics and professional attitude is seen in various societies based on their belief system and views on the issue. Dentists'' attention to work ethics will result in rendering better services، and reduction of stress in their professional work the aim of this study was to evaluate the attitude of faculty members towards professional work ethics at Hamadan University School of Dentistry. (2012) The study population in this cross – sectional study included the entire faculty members of Hamadan University Dental School. The sampling method was census. The survey instrument was a 2-part questionnaire which included demographic information and 36 specific questions related to attitude towards work ethics، SPSS (16) predictive analytics software was used for statistical analysis. Results indicated that most participants were females (56/7%) with specialized dental degree (83/5%) and married (66/7%). Participants were mostly assistant professors (76. 7%) in their 30’s (60%) with 10-20 years of work experience (53%). Statistical analysis indicates that there is no a significant relationship between demographic variables and dentists’ attitude towards work ethics. A total of 63. 14% of dental faculty demonstrated a positive attitude and strongly approved of the concept of work ethics whereas 27. 31% simply agreed with the issue. Views and attitudes towards work ethics and professionalism are far from satisfactory among dental faculties. Therefore، continuing education courses are recommended for dental professionals to broaden their perspective on this issue.

Early diagnosis of bone pathologic lesions is of paramount importance in enabling the clinician to provide immediate and appropriate dental treatment. Conventional radiographs have always been used as the primary and fundamental means of diagnosis، treatment and follow up of endodontic lesions. In recent years، digital imaging has gained high popularity for diagnostic purposes. The aim of this study was to assess the accuracy of digital radiographic imaging compared to conventional radiography in detecting mechanically created jaw bone lesions. This experimental study was conducted on the lower jaw of a cow cadaver. Mechanical lesions with different depths (0. 5، 1، 1. 5، 2، 2. 5، 3، 4،5mm) were drilled into the jaw with a surgical bur (021). A digital radiograph followed by a conventional image with E-speed film were obtained and the images were evaluated by five examiners. Wilcoxon Signed-Ranks test was used for statistical analysis. According to the results of this study، examiners were more successful in detecting lesions with DDR than with conventional radiography. The mean value and standard deviation of detection score were 1/25 ± 0/98 for conventional and 1/85 ± 0/53 for digital methods. This difference was statistically significant. (P< 0. 001) The adequacy of digital radiography in detection of bone lesions is much higher than conventional radiography. Digital images are recommended for diagnostic purposes.

The origin of metastatic Melanoma is unknown in approximately 5-10% of the patients. Various suggestions have been made for the primary origin of this lesion. In this article، a rare case of metastatic Melanoma is reported in submandibular area.

A 20 year-old woman was referred with a cystic lump in the submandibular area. She reported a pigmented macule on her lip that was completely regressed at the time of clinical evaluation. Excisional biopsy showed the lesion to be Metastatic Melanoma. The diagnosis was confirmed by Immuno-histochemcial staining for HMB45 and S100 markers. The patient is reported to be free of disease in four-year follow up based on the clinical as well as Para clinical evaluation.

Total excision of the solitary lesion is suggested in patients with metastatic Melanoma with unknown origin and regression of the primary lesion.