RESUMO
Statement of Problem: In diagnostic studies of dentistry, estimation of the mesiodistal width of the unerupted teeth and the required space for their eruption in relation to the space analysis and evaluation of the root-crow ratio is of great importance
Purpose: This study aimed to evaluate the ratio between the real and radiographic length and mesiodistal width of mandibular premolars and provide a formula for prediction of the teeth length and mesiodistal width
Materials and Method: Fifty six extracted teeth of mandibular first and second premolars of patients and their panoramic radiographs with good quality were collected. The extracted teeth were divided into four groups: T34 [lower left first premolar], T44 [lower right first premolar], T35 [lower left second premolar], and T45 [lower right second premolar]. Then the length and mesiodistal width of both the panoramic images and the extracted teeth were measured. All of the obtained data were analyzed through t-test, two tailed student and linear regression model
Results: It was shown that the vertical magnification of the mandibular first premolars was almost 11.4%-12.1% and that of the mandibular second premolar was almost 16%. The horizontal magnification of the mandibular first premolar was almost 15% and that of the mandibular second premolar was almost 26%. No statistically significant differences were found between the true and radiographic length and mesiodistal width and the magnifications of the left side premolars compared with right side premolars. To determine the real mesiodistal width and length size, some equations are introduced
Conclusion: The panoramic radiographs taken in this research by X-ray imaging machine are feasible and reliable for estimating the actual premolar teeth length and mesiodistal width using specific equations for each teeth in the lower jaw
RESUMO
Heavy metal ions and their compounds are essential for bacterial growth at very low concentration; however most of them have toxic effects at high concentrations. For Escherichia coli, simultaneous resistance to several heavy metal ions and antibacterial agents is reported. The present study is conducted to measure simultaneous resistance of some E. coli isolates, in which their tellurite sensivity had been investigated before, to heavy metal ions and antibiotics. In this laboratory study, in order to test bacterial resistance, the experimental investigations of antibiotic disc diffusion [agar serial dilution] were used to test 22 E. coli strains resistancy [5 isolates, MIC range <10 micro g/ml], [6 isolates, Minimum Inhibitory Concentration [MIC] range 10-40 micro g/ml] and [11 isolates, MIC range >40 micro g/ml] to heavy metal ions [Ag, Hg, Cd] and antibacterial agents; [Amoxicillin, Tetracycline and Gentamicin], simultaneously. These strains were isolated from urinary tracts and feces floor of clinical samples. Data were analyzed using PROBIT method. For Ag, the MIC was similar for all the isolates, therefore no difference was observed between sensitivity to tellurite and Ag. MIC level for Cd was significantly higher in the isolates, which were highly resistant to tellurite [p=0.008]. In case of Hg the isolates which were highly resistant to tellurite had a higher MIC than that of other isolates and the difference was statistically significant [p=0.008]. There were no significant differences between simultaneous resistance to heavy metals and different antibacterial agents; [Amoxicillin, Tetracycline and Gentamicin]. In total, there were statistically significant relationship between resistance to the antibacterial agents [Am, Gm, Te] and resistance to heavy metal ions in the tested isolates