Journal of Isfahan Dental School
Year:2008 | Volume:4 | Issue:2|Papers Count:9

Introduction: There are different reports about the rate of maxillary canine impaction in different communities and races. The aim of this study was to determine the prevalence of maxillary canine palatal impaction in 10-11 years old children in Mashhad.Methods and Materials: In this descriptive cross sectional study, 1472, 10-11 years old students in Mashhad were selected through random cluster sampling process. Dental age was considered as an important criterion in clinical diagnosis of impaction. Suspected children to impaction in clinical examination were referred to Mashhad Dental School for radiographic examination and preventive treatment. The condition of lateral incisor teeth was inspected in children who were suspected to impaction. The data were analyzed using descriptive statistics and Fischer's exact test.Results: Considering dental age, 5.5% of children were suspected to impaction in clinical examination and referred for radiographic examination. The prevalence of maxillary canine palatal impaction in the population evaluated was 1.1%. Impaction was more prevalent in girls comparing to boys.

Introduction: Bleaching gel may increase micro leakage in composite restorations. Also by using proper adhesive agents, micro leakage will be reduced. The aim of this study was to evaluate the micro leakage of composite restoration by using self etch and total etch (fifth, sixth and seventh generation) of adhesive agents after using 35% carbamide peroxide gel.Methods and Materials: After preparation of CLV cavity in the buccal and lingual surface of 30 extracted bovine teeth, the teeth were divided to six groups. (n = 5) Then one of the adhesive agents, Single bond (self etch, groups 1 and 4), prompt L- POP (total etch, groups 2 and 5), G Bond, (Self etch Group 3 and 6) were used in the cavity and then restored with Z100 composite. Then groups 4, 5 and 6 were exposed to 35% carbamide peroxide gel three times for 30 minutes each time. The specimens were termocycled in 5 ± 2oC and 55 ± 2oC c for 500 times and stored in basic fusing for 24 hours. Then the teeth were sectioned and dye penetration was evaluated by Stereomicroscope (× 40). The results were analyzed by suing kraskal- wallis and Man- whithny tests (a < 0.05).Results: Ther was no significant difference in micro leakage after using different adhesive and 35% carbamid peroxide bleaching gel (p value =0.63). Micro leakage in gingival margin was higher than incisal margin (P value = 0.037).Conclusion: By using total etch and self etch (5th, 6th, 7th generation) of adhesive agents and 35% cabamid peroxide gel, micro leakage was similar and micro leakage in gingival margin was higher than incisal margin

Introduction: As biomechanical preparation of root canal system is not always completely accomplished because of morphological and physical barriers, to obtain a sterile root canal for the success of endodontic treatment, use of chemical solvents is essential. The aim of this in vitro study was to compare effects of Ca (OH)2 and NaOCl in single and combination usage for this purpose.Methods and Materials: In this experimental study, five groups of 40 pieces of human umbilical cord samples were placed in 10 ml of different solvents for 1 wk. The weight of samples was adjusted to 0.03 g. Experimental solvents included: 1) Calcium hydroxide solution (0.6g per ml), 2) 0.5% sodium hypochlorite, 3) 5% sodium hypochlorite, and 4) calcium hydroxide solution for 1 wk and then 0.5% sodium hypochlorite for 30 min, 5) Normal saline. Tissue solubility of these solvents was compared by weight changes of samples after 1 wk. Data was analyzed with Kruscal- wallis and t- student tests.Results: There was no significant difference between calcium hydroxide (Group 1) and salin (Group 5). Other groups had significant differences (p value < 0.01).Conclusion: According to findings of this study, tissue solubilizing of 0.5% NaOCl is less than 5% although both have more solubilizing power than Ca (OH)2. Pretreatment with Ca (OH) 2 could not enhance the tissue dissolving effect of 0.5% NaOCl.

Introduction: Dentin hypersensitivity is a common condition of transient tooth pain associated with a variety of exogenous stimuli. The clinical cause of dentin hypersensitivity is exposed dentinal tubules as a result of gingival recession and subsequent loss of cementum on root surfaces. Two principal treatment strategies are used; Dentinal tubules can be covered by gingival grafts or dental restorations and desensitization of the nerve tissue can be done within the tubules using potassium nitrate. The Purpose of this study was to compare effect of two desensitizing agent nitrate potassium and sodium fluoride after periodontal surgery.Material and methods: In this clinical trial 12 patients that had peridontal surgery at minimum 3 quadrants, in each there was one sensitive tooth, were selected. The degree of sensitivity measured before using nitrate potassium and sodium fluoride the same as control group. Potassium and sodium fluoride gels used on the quadrants (upper or down. The degree of sensitivity measured after 7 and 14 days. Data analysis was done in SPSS software by Freedman and Willcoxon tests.Results: After 7 and 14 days in the all groups, decrease of sensitivity was statistically significant. But after 14 days, between three groups, there were no statistically significant differences.Conclusion: Even though using of nitrate potassium 3% and sodium fluoride 2% cause significant reduction of tooth sensitivity in a 2 weeks period but in compare to the control group did not show any superiority. Further study is needed to confirm this result.

Introduction: As bruxism and clenching are important parafunctional habits that cause disorders in masticatory muscles and temporomandibular joint (TMJ), and many patients are unaware of these parafunctions, this study was done to evaluate prevalence of these parafunctional habits and oral related signs.Methods and Materials: In this descriptive, analytic and cross-sectional study, 683 patients came to dental clinics in Isfahan were randomly selected and examined. The examination contained evaluation of history of bruxism and clenching and clinical examination for it including physical examination of masticatory muscles and TMJ, oral exam for finding occlusal wear, shining of amalgam fillings, cheek biting, scalloped tongue borders, tooth mobility, and masticatory muscles' hypertrophy. The data was analyzed and X2 was used.Results: The overall prevalence of bruxism and clenching was 14.6% and 29.3% respectively. 16.8% of females and 12.2% of males had bruxism. The prevalence of clenching had no statistical difference in two genders. In bruxers, dental wear (55%) and pain of masticatory muscles (53%) were the most prevalent signs. In persons with clenching, dental wear (42%) and temporomandibular joint sound (37.5%) were the most prevalent signs.Conclusion: The prevalence of clenching was more than bruxism. In bruxers, dental wear and pain of masticatory muscles and in persons with clenching dental wear and temporomandibular joint sound were most prevalent signs. There was a relation between oral signs and bruxism or clenching. By this consideration, more exactly prevalence evaluation of these parafunctional habits was possible.

Introduction: Base metals are being increasingly used in casting procedures in dentistry. Since recasting these alloys in laboratory might have negative effects on marginal fitness, it seems necessary to study the effect of recasting procedures more carefully. The goal of this study was to study the effect of recasting base metals on vertical marginal fitness of crowns with different marginal configurations with different percentages of alloys.Material and Methods: In this study, two dies made up of brass with dimensions of prepared premolars and marginal configurations of shoulder bevel 450 and shoulder 1350 were prepared by CNC machine. Total of 30 copings were waxed and cast, 15 copings for each die. Copings were further subdivided in to three groups A, B and C. Group A consisted of 100% new alloy, group B consisted of combination of 50% new alloy and 50% old alloy, group C consisted of 100% recast alloy. After copings were seated, vertical distance from margin of the restoration to margin of the die was measured by metric microscope with Moticam camera at four points of buccal, lingual, mesial and distal. Data were analyzed by two- and one-way ANOVA and t- test.Results: Group A1 (135º shoulder finishing line cast with 100% new alloy): 156.11 micron. Group A2 (45o shoulder bevel finishing line cast with 100% new alloy): 99.74 micron. Group B1 (135o shoulder finishing line cast with 50% new alloy and 50% recast alloy): 273.38 micron. Group B2 (45o shoulder bevel finishing line cast with 50% new alloy and 50% recast alloy): 123.07 micron. Group C1 (135o shoulder finishing line cast with 100% recast alloy): 369.40 micron. Group C2 (45o shoulder bevel finishing line cast with 100% recast alloy): 106.97 micron. There were statistical differences between groups A, B and C in vertical gap when three different percentages of alloys (100% new with average gap of 127.93 micron, 50% new+50% recast with average gap of 198.22 micron, 100% recast with average gap of 238.18 micron) were used (p value = 0.036). There were statistical differences in mean vertical gap distance between different preparations (shoulder bevel 45o, shoulder 135o) within each group (100% new, 50% new + 50% recast, 100% recast).Discussion: When three different percentages of alloys were used (100% new alloy, 50% new + 50% old, 100% old), 100% new alloy showed the least mean vertical gap compared to other two groups. In shoulder 135o there were statically differences between group A and C only and in shoulder bevel preparation there were no statically differences between groups A, B and C. In group C (100% recast) there were significant differences between two preparations (shoulder bevel 45º and shoulder 135o). 

Introduction: Osteochondroma is one of the most common benign bone tumors and however is relatively uncommon in the jaws. The aim of this study was to review the literature about osteochondroma and to report a case of large osteochondroma in temporomandibular joint space. Treatment included osteotomy of condylar neck followed by reshaping.Case report: This study presents a 26-year-old man with a large osteochondroma in temporomandibular joint space in left side of his face with the complaint of facial asymmetry (deviated to the right side). The patient was admitted to the Hospital of Taleghani in Tehran, in October 2002. Conclusion: Condylectomy cannot be recommended as routine in all cases. Common surgical treatments include condylectomy and reconstruction. If the tumor involves only a limited area of the condylar surface, then preservation of the remaining portion of the condyle and reshaping should be done. Reasons for not taking such a conservative approach are the possibilities of malignancy and the risk of recurrence. In this case report, because of large size of tumor, zygomatic arch was broken and osteotomy of condylar neck was used and remaining part was reshaped. The zygomatic arch was returned to the primary position and fixed with miniplate and screw.

Introduction: Thalassemia is a genetically determined disorder of hemoglobin syntheses which results in problematic erythropoisis and finally leads to compensative dilation of bone marrow spaces and associated multiple skeletal disorders. These patients routinely are under hyper transfusion and in some cases spelenectomy may be accomplished. Treatment of dentofacial deformities in these patients is a complicated procedure because of possibility of massive intra operative hemorrhage; in these patients, the most common orthognatic surgery is only shaving of expansive lesions in maxilla or segmental osteotomies. In this paper, we report a thalassemic patient in which maxillary impaction surgery and chin osteotomy were carried out simultaneously.Case report: Patient was a 20 years old woman with thalassemia major complaining from facial deformity. Her problem consists of maxillary protrusion, severe gummy smile, increased lower facial height and deficient chin. After complete Hematologic consideration, simultaneous maxillary impaction and advancement genioplasty was accomplished. Six months follow up showed stable results.