14 research outputs found

    Comparison of spring characteristics of titanium-molybdenum alloy and stainless steel

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    Titanium-molybdenum alloy (TMA) and stainless steel (SS) wires are commonly used in orthodontics as arch-wires for tooth movement. However, plastic deformation phenomenon in these arch-wires seems to be a major concern among orthodontists. This study aimed to compare the mechanical properties of TMA and SS wires with different dimensions. Seventy-two wire samples (36 TMA and 36 SS) of three different sizes (19×25, 17×25 and 16×22) were analyzed in vitro, with 12 samples in each group. Various mechanical properties of the wires, including spring-back, bending moment and stiffness were determined using a universal testing machine. Student’s t-test showed statistically significant differences in the mean values of all the groups. In addition, metallographic comparison of SS and TMA wires was conducted under an optical microscope. The degree of stiffness of 16×22-sized SS and TMA springs was found to be 12±2 and 5±0.4, respectively, while the bending moment was estimated to be 1927±352 (gm-mm) and 932±16 (gm-mm), respectively; the spring-back index was determined to be 0.61±0.2 and 0.4±.09, respectively (p<0.001). There were no statistically significant differences in spring-back index in larger dimensions of the wires. Systematic analysis indicated that springs made of TMA were superior compared to those made of SS. Although both from economic and functionality viewpoints the use of TMA is suggested, further clinical investigations are recommended

    Evaluating the comparative effects of Listerine zero and Persica mouthwashes on the periodontal conditions of fixed orthodontics patients

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    Background and Objective: Periodontal problems are very common among patients undergoing fixed orthodontics treatment. Using mouthwashes such as Listerine and Persica is recommended in order to prevent such complications. There have, however, been no information on the comparative effects of Listerine and Persica mouthwashes so far. Thus the comparative study presented here under the title of “Evaluating the comparative effects of Listerine Zero and Persica Mouthwashes on the Periodontal Conditions of fixed orthodontics Patients was conducted at the Department of Dentistry of Azad University of Tehran. Materials and Methods: A blind randomized clinical trial was conducted on 30 patients. All subjects were between 20 and 50 years of age; had been under fixed orthodontic treatment for at least two months; did not have serious systemic health complications; had a minimum of 5 teeth in each quadrant for evaluation. Root planning and scaling were conducted on male and female subjects prior to their entry into the study. The SI, GI, PI, and BOP indices of each subject were then recorded in the base-line stage. The subjects were then divided into two random groups. The first group was treated with Persica (Pursina Co., Iran) and the second group with Listerine Zero (Johnson &amp; Johnson, New Jersey, USA). The two groups were followed up twice after two and four weeks of treatment and their SI, GI, PI, and BOP indices were recorded. Results: The SI, GI, PI, and BOP indices were found to have changed by similar amounts in both groups (P&lt;0.12). The changes in GI, PI, and BOP were, however, statistically significant within each group (P&lt;0.02). The changes in SI index within the Persica group were found to increase only within the first two weeks of treatment (P&lt;0.05). Conclusion: Following the comparative study described above, both mouthwashes appear to positively affect the periodontal condition of fixed orthodontics patients. Both mouthwashes were, however, found to have similar effects

    The Effect of an Acidic Food-Simulating Environment on the Shear Bond Strength of Self-Ligating Brackets with Different Base Designs

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    Aim. This study aims to evaluate the effect of acidic food simulant and (acetic acid 3%) on the shear bond strength (SBS) and adhesive remnant index (ARI) scores of one conventional and three different self-ligating brackets with different base designs. Materials and Methods. Freshly extracted first maxillary premolars (n=160) were embedded in resin blocks. A conventional stainless steel bracket, Equilibrium 2, and three types of self-ligating brackets, Speed, In-Ovation R, and Damon 3MX, were bonded to teeth and exposed to distilled water (groups 1, 3, 5, and 7) or acetic acid 3% (groups 2, 4, 6, 8) for 12 weeks. SBS and ARI were calculated and statistical analysis was performed with the analysis of variance (SBS) or χ2 test (ARI) to compare values between the different groups. Results. Equilibrium 2 and In-Ovation R showed a significantly lower SBS in the acidic environment than in distilled water. Significant differences in ARI scores were found for Equilibrium 2 after immersion in an acidic environment, shifting from 0 in distilled water to 2 in an acidic environment. Conclusions. Equilibrium 2 and In-Ovation R brackets showed a significant decrease in SBS after a 12-week immersion in acetic acid 3%, although all groups showed clinically acceptable SBS. Equilibrium 2 showed significant differences in ARI scores when exposed to acetic acid 3%

    Quality of research articles published in Iranian Dental Journals

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    ABSTRACT Objective: To evaluate the quality pertaining to the various structural components and aspects of research articles published in Iranian journals of dentistry in the first six months of the year 2006. Methodology: This descriptive study assessed the quality of 100 original articles published in Iranian Journals of dentistry in terms of their various structural components including abstracts, introductions, methodology, results, discussions and references. Based on 52 variables the articles were classified into three categories of &quot;adequate&quot;, &quot;relatively adequate&quot; and &quot;inadequate&quot;. Data analysis was done using Chi-square statistical test. Results: The mean number of authors for each article was 2.9+0.84. Failure rate to report the &quot;reliability&quot; of the instrument of measurement was 96%, followed by failure to justify the sample size (93%). Justification for publication was not reported in 73% of the articles and 87% didn&apos;t cite the limitations and valuable findings of the study. No statistically significant association was found between the quality of published articles and study designs, number of authors and references (P&lt;0.3)

    Assessing the Amount of Interdental Bone in Posterior Areas of the Mandible for Placing Orthodontic Mini-Implants

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    Objective: The aim of this study was to assess the amount of interdental bone in posterior areas of the mandible for placing orthodontic mini-implants to provide and control anchorage in orthodontic treatment.Materials and Methods: The amount of interdental bone in areas between the second premolars and first molars, first and second molars on the right and left sides of the mandible were determined in fifty patients by RVG using periapical radiographs. The images were assessed using Cygnus Media Software to determine the mesio-distal width of the interdental bone, starting at the crest of the alveolar bone (2 mm below the CEJ) every one millimeter up to 12 mm from the CEJ. The actual amount of interdental bone and the effect of related factors were assessed using chi-square test at a 95% confidence interval.Results: The minimum desired interdental bone width for placing mini-implants, 3 mm from the CEJ, between the second premolar and first molar and the first and second molars of the mandible on both sides were significantly different (p<0.01): 1.8 mm (31%) more apical in the area between the second premolar and the first molar. There was also a statistically significant difference between the areas under study on the right side (p<0.002), which was 2.2 mm (44%) more apical in the area of the second premolar and the first molar.Conclusion: The most secure site for placing orthodontic mini-implants in the mandible is between the first and second molars at the height of 5.8 mm from the CEJ

    Back-scattered and secondary electron images of scanning electron microscopy in dentistry: A new method for surface analysis

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    Objective: A scanning electron microscope (SEM) is a popular tool for investigating the root canal surface to visualize dentinal tubules, the smear layer and various root canal filling materials in endodontics. Most of the SEM micrographs taken in endodontic research are in secondary electrons (SE) mode, in which the topographic view of a subject can be demonstrated without giving any information about the real structure. Back-scattered electron (BSE) images are also used, which reveal some information about the internal structure while providing no topographic details. The aim of this study was to investigate the possibility of using back-scattered (BSE) and secondary electron (SE) modeofscanning electron microscopy (SEM) together for obtaining detailed information about biomaterials in relation to dental structures. Materials and methods: Mesiobuccal roots of four permanent maxillary molars were cleaned and shaped with rotary instruments. Two samples were obturated with guttapercha and sealer. After 2 weeks, gutta-perch was removed using rotary instruments and chloroform. In the other phase of the study, white mineral trioxide aggregate was mixed and packed into five glass tubes and exposed to blood, deionized water, synthetic tissue fluid and egg white. All the samples were prepared for visualization under SE and BSE modes of SEM to observe the characteristics of material remnants and surface structures. Results: BSE mode illustrated different grey scale views which made it possible to differentiate dentin chips from filling material remnants on the surface of root canal dentin. In addition, SE mode focusedonimage topography, while a BSE detector showed new texture formationonthe surface of white mineral trioxide aggregate exposed to proteinaceous fluids such as blood or egg white. Conclusions: Mapping BSE and SE micrographs helped ustobetter understand the structure of materials on the surface ofroot canal dentin and MTA. Moreover, analysis of structure of materials on the surface of root canal dentine and MTA can be performed better by mapping of BSE and SE micrographs. © 2012 Informa Healthcare.Link_to_subscribed_fulltex
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