فهرست مطالب

  • Volume:4 Issue: 3, 2010
  • تاریخ انتشار: 1389/09/20
  • تعداد عناوین: 10
|
  • Fariborz Amini, Maral Khazali, Farhang Mahmodei, Siamak Hematpour Page 63
    Objective
    The aim of this study was to determine salivary concentrations of Nickel , Chromium and Cobalt ions in patients with fixed orthodontic appliances.
    Materials And Methods
    This study was performed on salivary samples of 60 subjects including 30 subjects (20 females and 10 males) who were under orthodontic treatment with fixed orthodontic appliance for average of 1.5 to 2 years as study group and 30 individuals(20 females and 10 males) without any appliance therapy as control group. The chemical analyses of saliva was done with an electrothermal atomic absorption spectrophotometry to detect the metal ion content of the saliva. The Mann-Whitney u-test was used to analyze significance of the differences between two groups.
    Results
    Examining the content of Nickel in the saliva of orthodontic patients and controls, the Nickel content of saliva in study group was significantly higher than the controls (p
    Conclusion
    fixed orthodontic appliances release measurable amount of Nickel and Cobalt when placed in the mouth however; this increase doesn’t reach toxic levels in saliva.
    Keywords: Nickel, Chromium, Cobalt, salivary concentration, fixed orthodontic appliance
  • Masoud Davoudiana Page 67
    Aim: The rapid evolution of digital radiographic systems and digital tracing software is having an impact on cephalometrics, slowly replacing traditional hand-tracing methods on hard copies of radiographic films. The purpose of this study was to examine and compare the reliability and reproducibility of digitization using Onyxceph imaging software (Version 2.6.14) with conventional manual techniques.
    Materials And Methods
    Thirty lateral cephalograms of an office patients previously treated, randomly selected and were evaluated by two
    Methods
    manual tracing and indirect digitization using Onyxceph imaging software (Version 2.6.14). Method error (reliability) using duplicate measurements for each method, and comparison of both techniques (reproducibility), were investigated using alternative statistical methods, paired t-test and pearson’s Correlation.
    Results
    All the measurements showed good reliability in both methods except for nasolabial angle in the manual method. Between the two methods, sum of posterior angles measurement had statistically significant difference.
    Conclusions
    Onyxceph tracing software (version 2.6.14) can be used instead of the time consuming conventional method for lateral cephalometric analysis with good accuracy.
    Keywords: Accuracy, conventional cephalometric tracing, cephalometery, software
  • Ladan Eslamian, Nasim Shams, Bahar Shams Page 78
    Aim: Awareness of orthodontic treatment need is very important in hygienic planning and dentistry insurance. This study determined the rate of orthodontic treatment need based on IOTN index in 12-16 year old patients undergoing orthodontic treatment in 4 Tehran dental schools and 2 orthodontic private offices in 2004-2006.
    Materials And Methods
    In this descriptive research, study casts and charts for 209 patients aging 12-16 in 4 dental schools of Tehran and 2 orthodontic private offices were surveyed based on IOTN index in different ages and in terms of gender. Classifications (CI,II,III), overjet, openbite, deepbite, crossbite, contact displacement, supernumerary, ankylosed, impacted and missing teeth, cleft lip, cleft palate and lip, cleft palate, and facial asymmetry were evaluated, and compared with IOTN results achieved from 22, educational districts of Tehran. Chi-square, Fisher''s Exact and ratio equality tests were used to analyze the data.
    Results
    Among 209 patients under treatment, 22.5% needed very severe treatment (grade5), 33% severe(grade4), 4.36% average (grade3) and 8.2% needed less or no treatment (grades1&2). The number of girls being treated was more than boys (66.5%); most of the patients under treatment were 12 years old (67 persons= 32.1%); the most common causes of orthodontic treatment were contact displacement 57.4%, overjet 22.5 and deepbite 17.7%.
    Conclusion
    Regarding treatment need among patients under treatment, we concluded that most of the treated patients needed treatment based on IOTN and the number of patients needing simple treatment was very small, so treatment decisions were made according to IOTN.
    Keywords: Malocclusion, Treatment need, IOTN
  • Allahyar Geramy, Hannane Ghadirian, Mohammad Javad Kharazifard, Tajgaldi Katooki Page 85
    Aim: anterio-posterior discrepancies and differentiating the involved problems make a major part of our diagnosis and treatment. The main goal of this study was to compare the
    Materials And Methods
    In this cross sectional study, 105 pre-treatment lateral cephalograms (42 males and 63 females; 12±3 years old) The cephalograms were classified according to Angle classification. In all cephalograms, the ANB angel, Wits analysis, β angel, µ angel, Jaraback index and Bjork angels were measured.
    Results
    The highest accordance between clinical observation and Wits appraisal was seen in class III group. The most accordance of the ANB angel was in the class II group.The best correlation was found between µ angel and β angel (r=0.912). The correlation of ANB angel with µ angel was the weakest (r=0.769).The results showed that when angle is smaller than 12.7 degrees, the patient is skeletal class II and the patients whose angle is larger than 19.1 degrees are classified in class III group.
    Conclusion
    All of four sagittal parameters (ANB angle, Wits, β angle and µ angle) were well-correlated. The best correlation was found between µ angel and β angel. The correlation of ANB angel with µ angel was the weakest. angle and angle are proper tools to show skeletal class II and class III, but these angles cannot differentiate prognatic or retrognatic jaw.
    Keywords: Antero, posterior discrepancy, ANB, β angle, μ angle, Wits Appraisal
  • Tahereh Hosseinzadeh- Nik, Javad Chalipa, Reza Jelodar Page 91
  • Esfandiar Akhavan Niakia, Javad Chalipab, Davoud Abdollahi C., Mohammad Moslem Imanid Page 95
    Aim: previous designs like intrusion arch (Burstone) and Utility arch (Ricketts) to intrude anterior teeth in patients with deep bite had some advantageous, which required new consideration. The present study investigated new designs in making intrusion arch.
    Materials And Methods
    PATRAN and NASTRAN programs were used in this computerized simulation study. Burstone, Utility arch designs; proposed methods i.e. A and B were loaded in 11 different cross sections and in 3 situations.
    Result
    the results indicated a lower load-deflection rate in newly designed intrusion arches and a more appropriate condition for implementation of a light continues forces .otherwise, the extent and the type of this placement in posterior blocks due to intrusion arch reaction, were in better condition in new designs comparing with those impervious ones.
    Concluson: Considering the advantages of the proposed designs it seems that their implementation would lead to better results in incisor teeth intrusion.
    Keywords: Intrusion, Intrusion arch, Deep bite, Load, deflection rate
  • Barat Ali Ramazanzadeh, Mostafa Shahabi, Mohsen Merati Page 104
    Aim: Determination of overall and anterior Bolton ratios in people having normal occlusion in Iran and checking the effect of sexuality upon Bolton ratios in the aforementioned population and pinpointing the ability to apply normal quantities offered by Bolton in the Iranian population.
    Materials And Methods
    The study is a cross-sectional descriptive one by surveying study casts provided from 56 high school students (28 boys and 28 girls) having normal occlusions. Bolton ratios were considered in boys and girls separately. Statistical computations were conducted according to student t-test.
    Results
    The total mesiodistal width of 12 permanent teeth and 6 anterior teeth in boys exceeded that of girls however this discrepancy has not statistically significant difference. The quantity of the overall and anterior Bolton ratios did not have statistically significant differences in boys and girls. The mean and standard deviation of the overall and anterior ratios in Iranian population were 91.58±2.03% and 77.73±3.17% which did not have statistically significant differences from the normal quantities offered by Bolton (P
    Conclusion
    The normal ratios offered by Bolton can be used in the Iranian boys and girls needing orthodontic treatments.
    Keywords: Bolton ratios, tooth size, Iranian population
  • Gholamreza Shirani, Mahnaz Arshad, Sohrab Asefi Page 109
    Supernumerary tooth is a rare event, which is usually found coincidentally in radiographic examination. The prevalence of this event is 1-3% with different prevalence for primary and permanent dentition. Supernumerary teeth may cause various clinical problems including: delayed or failure of eruption, displacement or rotation of permanent teeth and cyst formation.
    The purpose of this study was to present the case of a 9-year-old boy who had a large dentigerous cyst around his primary mandibular left premolar that was enucleated with the tooth. A year after this enucleation, we have observed a supernumerary tooth in mesial of canine. It is a reasonable question that “can the supernumerary tooth formation relate to the dentigerous cyst around impacted tooth?”
    Therefore, it is necessary to perform more pathological investigation in this aspect to answer this question.
    Keywords: Supernumerary Tooth, Dentigerous cyst, Odontoma, Primary Dentition
  • Azita Tehranchi, Hossein Behnia, Majid Heidarpour, Bahman Toutiaee, M. Javad Khosropour Page 114
    Aim: Analyzing the changes made during distraction osteogenesis (DO) in asymmetric mandibles
    Materials And Methods
    This study was performed on a three dimensional model of a desiccated mandible, based on a finite element method. The distraction devices were placed with an angle of 90, 60 or 30 degrees to the oblique surgical cut. The directions of the pins were such that the 30 and 60 degree pins were placed in a counterclockwise direction relative to the perpendicular pin. The distractors were opened for 15 and 30 mm. The amount and direction of movement of proximal and distal segments and the displacement of pogonion were evaluated in all three planes of space.
    Results
    In the distal segment, the maximum change in pogonion was seen in 30 degree angle. In the proximal segment, if the distraction device was used with 90 degree angle, the condylar process rotated in the clockwise rotation. In 30 degree angle, this process rotated in a counterclockwise direction and the minimum rotation was seen in 60 degree angle.
    Conclusion
    If gonial angle is to be augmented in a downward direction maximally, the angle of distraction device to the surgical cut is critically important (that is, it should be perpendicular to surgical cut). By use of perpendicular mode, ramus slops more posteriorly. It is better to use the distraction pin with a thirty degree angle if the ramus needs to be uprighted. The oblique surgical cut, irrespective of the distraction pin angle, increases the anterior facial height.
    Keywords: Distraction Osteogenesis, mandibular asymmetry, mandibular lengthening, finite element method
  • Nasrin Farhadian, Amirfarhang Miresmaeili, Loghman Rezaei Soufi, Fahimeh Baghaei Page 121
    Aim: of this in vitro study was to evaluate the effects of Co2 laser irradiation on demineralization adjacent to orthodontic brackets and their shear bond strength in human premolar teeth. Enamel demineralization adjacent to orthodontic brackets is a major problem that requires new professional method independent to patient cooperation.
    Materials And Methods
    Sixty human premolars were randomly divided to two groups (n=30). Group1, enamel surface irradiated with Co2 laser. Group2 without any enamel surface treatment. In both groups, a bracket at buccal surface was bonded with Transbond XT and cured with conventional light cure. Demineralization in all sample induced with artificial caries solutions. A universal testing machine was used to determine shear bond strengths. The teeth were sectioned bucco-lingually and were evaluated under polarized light microscope. Average lesion depths were calculated from three depth measurements. The Two independent sample T- tests were used to compare the study type group in detail.
    Results
    The mean of shear bond strengths in the group1 and 2 were 13.90±5.01and 15.84 ±3.68 Mpa respectively, but not statistically significant (P=0.102).The mean lesion depth in group1and 2 was 72.29±58.09 µm 120.01±76.49µm respectively, which was significant (P=0.018)
    Conclusion
    Co2 laser irradiation can reduce enamel demineralization while not affecting the shear bond strengths significantly.
    Keywords: CO2 laser, Shear bond strength, Enamel demineralization