Journal of Mashhad Dental School
Year:2007 | Volume:31 | Issue:SPECIAL ISSUE|Papers Count:10

Introduction: The major problems in patients treated with complete dentures are pathologic lesions caused by prosthetic dentures, retention, and stability, looseness of the prosthesis, prosthesis intolerance, chewing problems, speaking and esthetic problems, and food accumulation under the dentures. The purpose of this study was to assess different problems of denture prosthesis in some patients referred to the Mashhad Dental School in 2005.Materials & Methods: In this descriptive cross sectional study, 80 patients were selected. A questionnaire including questions about patients’ past medical history, complaints and symptoms leading to dissatisfaction with complete denture prosthesis was given to each patient. The statistical tests used to investigate differences between groups were the Chisquare and Fisher's exact test.Results: The highest percentage of pain caused by dentures was detected during eating. Food accumulation under the denture was the most common complaint. The highest percentage of partial tissue contact was found in the mandible base, which might have been due to shortness of the denture's borders. Statistical analysis showed that there was no significant difference in the complaints’ occurrence either between males and females or patients' medical conditions. There was a significant relationship between errors relating to maxillary overextension of denture bases and a patient's mucosa ulceration (P=0.035); and between errors relating to retention and the patient's complain to loose dentures in the mandible (P<0.001).Conclusion: Considering the limitation of this study, it can be concluded that the most common complaints of patients were related to food accumulation under the denture bases, the instability of the denture, esthetic problems and incorrect height of the occlusal plane.

Introduction: Each population or nation should have its own cephalometric criteria. There was no cephalometric norm available for the children of Mashhad hence we had to use another nation's norms available in textbooks. The aim of this study was to define the cephalometric criteria of Mashhad’s children with normal occlusion on the basis of natural head position (NHP) to be used in diagnosis and treatment planning. Materials & Methods: This was a cross-sectional descriptive study conducted on 30 girls and 30 boys with normal occlusion. Their mean age was 12 years, 4 months, 14 days; and 13 years, 4 months, 17 days respectively were selected randomly from 1,940 middle school children, who were Mashhad natives of 4 different areas of the city. Medical and dental histories, study casts, and lateral cephalograms in the natural head position were taken. Then, cephalograms were traced; statistical analyses were done; and results were extracted.Results: The results of this investigation were prepared as two tables, for boys and girls, showing the cephalometric criteria of Mashhad’s children with normal occlusion on the basis of NHP technique. These tables can be used for diagnosis and treatment planning of the above-mentioned population.Conclusion: With regards to the findings of this investigation, the axial inclination of the upper and lower anterior teeth and the lower third of the facial height of Mashhad’s boys are more than girls and both are more than Northern European children and these must be considered at the time of diagnosis and treatment planning.

Introduction: This report compares the use of a buccal fat pad (BFP) to Oro-Antral–Fistula (OAF) closure.Materials & Methods: BFP was used as a pedicle graft to OAF closure in 13 patients. Five of the patients underwent primary closure with BFP and 8 patients were treated with BFP after an unsuccessful closure with a buccal advancement flap. The BFP was left uncovered to epithelialize in all patients.Results: The BFP healed without complication within 3 to 4 weeks in all patients. The surface of the fat converted to normal mucosa.Conclusion: The findings support the idea that BFP is a useful, safe, and easy method to close OAF, especially recurrent OAF.

Introduction: The objective of this study is to increase the thickness of ridge in the dental pad of sheep by osteodistraction and interpositional methods.Materials & Methods: In this study, three sheep were used as subjects. The animals were medicated before surgery. Under the aseptic technique and general anesthesia, a full partial thickness flap was reflected over the lateral surface of the dental pad of the mandible. The thickness of the ridge was measured in anterior (test) and posterior parts (control) of the dental pad. The osteodistraction method was performed on one side. After a latent period of 10 days, one millimeter tension was applied and repeated every two days to achieve 4 mm distraction. An interpositional bone graft was performed on the other side of the mandible. The animals were controlled by food and medicine for eight weeks and then slaughtered. The net increase in the width of the ridge, as a result of the two techniques, was compared using the Mann-Whitney U test. The difference between control and test sections at each side of the ridge was detected by the Wilcoxon test.Results: The sheep tolerated the surgical procedure well. The soft tissue healed fine. The net width of the ridge increased to 1.83±1.15 mm in the distraction technique and 1±0.55 mm with the interposition method.Conclusion: Both methods can be used for increasing the width of ridge, resulting in an improved implant site. The distraction osteogenesis is a new alternative for grafting procedures in increasing the width of ridge. The advantages of this method are that no donor region is required. This method needs further studies to achieve optimal results.

Introduction: This study evaluated the effect of four oxidation techniques and porcelain firing on the thickness of oxide layer on base-metal alloy (Ni-Cr) and the relationship of oxide layer to porcelain-metal bond strength.Materials & Methods: This study had an interventional parallel design. Forty plates of base-metal alloy (Ni-Cr) were prepared and divided into four groups to be treated with four different oxidation techniques (A- no oxidation; Boxidation in air; C- oxidation under vacuum; and D- oxidation under vacuum followed by sandblasting). Vita opaque and body porcelain were applied on one side of the plates and baked in a furnace (Vacumat 200) following the recommended directions. The thickness of the oxide layer was measured by an electron microscope before and after porcelain application. The three-point bend test was used to measure the bond strength between porcelain and metal. The force which caused breakage was recorded by computer. Data were analyzed with a one-way analysis of variance (ANOVA) and the Duncan’s test with a 95% significance level. Results: The mean thickness of oxide layer was statistically different between groups before and after porcelain application (p=0.001<0.05). The Duncan multiple range test demonstrated significant differences in porcelain- metal bond strength between different groups of oxidation. Group D showed the best bond strength and was statistically different from the other groups.Conclusion: Oxidation under vacuum followed by sandblasting seems to control the oxide layer and improve the bond strength of porcelain to Ni-Cr alloy.

Introduction: There are many studies regarding the ability of AgNOR staining to show cellular proliferative activity; including its ability to distinguish the thyroid follicular adenoma and follicular carcinoma; comparison of dysplastic, and non-dysplastic mucosa; and the SCC grade I, II, III study of curettage normal endometer, hyperplasic and malignant comparison of different types of amelobelastoma. But regarding the comparison of normal buccal mucosa in cigarette smokers and nonsmokers with this staining and in this cytological study, there is only one experiment done by Sampio in Brazilia, and the samples in their study are less than ours. Materials & Methods: In this basilar-applied study, 60 patients were chosen from patients referred to the Surgical Department of the Mashhad Dental School. Thirty of them were cigarette smokers (smoking at least 20 cigarettes per day for 10 years) and the other 30 were nonsmokers. None of the patients in both groups had any oral lesions, systemic diseases, or stimuli in their mouth. After rinsing with 0.9% sodium chloride for 15 minutes, cytologic samples were prepared, dried, and fixed. The samples were stained using the AgNOR method and observed in immersion oil at 1000 x magnification. Finally, 100 cells were randomly selected; the AgNOR dots counted and their means recorded. The student t-test was used for data analysis. Results: In smokers, the mean AgNOR count was 3.6 and in nonsmokers it was 1.96 (P<0.000l). The percentages of cells, which showed at least 3 AgNOR dots in their nucleuses, were 83.6% in smokers and 21.46% in nonsmokers (P<0.000l).Conclusion: 1-Cigarette smoking increases cellular proliferation significantly. 2-This proliferation is observable with AgNOR staining before any clinical symptom has appeared.

Introduction: The purpose of this in vitro study was to compare the microleakge rate of class V compoglass-F and Fuji II LC restorations.Materials & Methods: Sixty class V cavity preparations with occlusal margins in enamel and gingival margins in cementum were prepared on the buccal and lingual surfaces of 30 extracted human premolar teeth. The teeth were divided randomly into 2 treatment groups. Group 1 was restored with Fuji II LC and group 2 with compoglass-F. After treatment, the samples were stored in tap water for 24 hours, then thermocycled, stained with dye, and finally scored for microleakge. The Mann-Whitney analysis of variance was done for data analysis (a=0.05). Results: The Fuji II LC had a higher degree of microleakge in occlusal and occlusal plus axial walls compared with compoglass (P=0.000). Where as, compoglass had microleakag in gingival and gingival plus axial walls (P=0.0003).Conclusion: The results revealed that Fuji II LC had less microleakage in the gingival margin in which enamel does not exist. Where as microleakage of compoglass restorations was significantly less than Fuji II LC in the occlusal wall where enamel exists.

Introduction: The objective of this study was the measurement and comparison of light output intensity at different points of lateral surfaces of conventional and novel designs of light-conducting interdental wedges.Materials & Methods: This study was conducted on five groups of five wedges. Group 1 (TW): the Sakti transparent wedge; Group 2 (TW1): the Sakti transparent wedge with one Reflective External Surface (RES); Group 3 (TW2): the Sakti transparent wedge with two Reflective External Surfaces (2RES); Group 4 (LW): the Luciwedge; and Group 5 (LW2): the Luciwedge with two Reflective External Surfaces (2RES). Light output intensity of a light-curing source and six points at the lateral surfaces of each wedge were measured through a diaphragm with a 1 mm diameter which had a selenium photoelectric cell connected to a moving coil galvanometer. Statistical analyses were done using the Kruskal-Wallis test, Hoteling’s Trace, Duncan test and Mann-Whitney U test.Results: There is a significant difference between light output intensity from different points of the groups. Light conduction efficacy of tested groups was significantly different and had decreased respectively TW2>LW>TW1>TW and LW2>LW).Conclusion: 1) Due to low light conduction efficacy in tested groups, we cannot obtain optimum polymerization and properties of proximal light-cured restorations through any of the light-conducting wedges or conventional light-curing units. 2) A new wedge mediated light-curing technique (the "Two-Step Wedge Application Technique") for a complete and homogenous polymerization in proximal composite resin restorations was introduced. 3) Adding External Reflective Surfaces (RES) on transparent wedges caused light conduction efficacy improvement and the 2RES design was superior to the others. 4) According to this study, a new type of light-conducting wedge with perfectly transparent material as the body of the wedge together with the 2RES design can be recommended.

Introduction: Recently, Adhesion of amalgam to dentin has been a common procedure. The aim of this study was to evaluate, the shear bond strength of amalgam to dentin using different adhesive systems.Materials & Methods: In this experimental study, amalgam dentin bond strength was determined using a punch out method in sections of human molar dentin. There were 5 treatment groups (n=20) consisting of 4 experimental groups (dental adhesives: One Coat Bond, Scotchbond MP, Panavia 21 and PQ1) and 1 control group (copal varnish: Copalite) followed by restoration with a spherical high copper amalgam.Results: The ANOVA and Duncan tests demonstrated a significant difference among groups (P<0.05). No significant difference in amalgam dentin bond strength was found among One Coat Bond (23,47MPa), Scotchbond MP (21,02MPa), and Panavia (20.06MPa), but there was a significant difference between the each of the mentioned groups with PQ1 and Copalite. The lowest bond strength was seen in PQ1 (13.15MPa) and Copalite (14.14MPa). Conclusion: High filler content in PQ1 was an important factor for creating the lowest amalgam dentin bond strength.

Introduction: The aim of this study was to compare a one-year clinical performance of two composites (Ariston PHC with Tetric) in class II cavity preparations.Materials & Methods: Ninety-six class I and II modified cavity preparations in identical patients were prepared. Metallic matrix was used for restoration of class II preparations. Ariston PHC and Tetric were used for restorations. The clinical criteria consisted of post-operative sensitivity, marginal discoloration, recurrent caries and marginal adaptation that were evaluated after one year.Results: The Fisher’s exact test, t-test and Chi-square Pearson were used for analysis of data (P£0.05). There was no significant difference between the two composites regarding post-operative sensitivity and marginal adaptation. Marginal discoloration by Ariston PHC was significantly less than Tetric. Most of this marginal discoloration was observed in proximal margins of class II restorations. There were only two recurrent caries (5.1%) in cervical margins of Tetric restorations. The maxilla and mandible did not have a significant effect on clinical criteria.Conclusion: There was no significant difference in post-operative sensitivity between the two composites. Marginal discoloration using Ariston PHC was significantly less than that of Tetric. No significant failure was observed when using any of the composites.