[Assessment of screening tests for methicillin - resistant staphylococcus aureus in patients undergoing surgery by molecular [PCR] and culturing methods]

Staphylococcus aureus is the main cause of surgical site infection, causing morbidity and mortality in patients undergoing surgery. Despite a lot of research on the best diagnostic method and Methicillin-Resistant Staphylococcus aureus [MRSA] screening in patients undergoing surgery, the most appropriate diagnostic method is still unknown. The question is whether Rapid Molecular [PCR] or the traditional microbial culture is the most suitable method? This study aimed at systematic reviewing of articles to evaluate molecular method in MRSA diagnosis and the necessity of screening patients before and after surgery to prevent infections and its subsequent outcomes e.g. mortality. Many searches in databases including the digital and medical inlm library and sites such as Science, JAMA,BMD, Springer were done since 2007 to August 2010. In total, 118 studies were selected regarding the following keywords; site surgical infection, Staphylococcus aureus, PCR, and culture. Two independent persons who selected the articles evaluated the designs of the studies and extracted the information using blinded method objectively. After a complete study of other articles, 50 articles were also eliminated, and 8 articles were finally entered the study. Data of culture diagnostic methods and PCR and the statistics of infection prevalence in surgical site were analyzed by Cumulative Pooled analysis. Eight randomized clinical trials of culture methods and PCR had been studied in MRSA diagnosis and screening in different surgeries. The average duration of study was 11.6 months in all articles. The relative risk of side surgical infection was 7.3% with MRSA in all articles and CI was 95% [0.969, 0.367]. The conformity between culture and PCR was 91%, PCR sensitivity 99.2% and PCR specificity 82.2%. The rates of MRSA infection before [0.65%] and after [0.35%] surgery were significantly different with screening. When screening was applied, the rate of infection with 0.95% CI decreased to 28.9% - 31%. Findings confirm the necessity of screening before surgery in order to determine the antibiotic prophylaxis preceding the surgery in those who carry MRSA. Thus, considering the specificity and sensitivity of PCR to microbial culture, molecular method is rapid and effective in diagnosis and screening of the patients who undergo surgery

[Effect of mandibular plane angle on image dimensions in linear tomography]

Accurate bone measurements are essential for determining the optimal size and length of proposed implants. The radiologist should be aware of the head position effects on image dimensions in each imaging technique. The purpose of this study was to evaluate the effect of mandibular plane angle on image dimensions in linear tomography. In this in vitro study, the vertical dimensions of linear tomograms taken from 3 dry mandibles in different posteroantenior or mediolateral tilts were compared with actual condition. In order to evaluate the effects of head position in linear tomography, 16 series of images while mandibular plane angle was tilted with 5, 10, 15 and 20 degrees in anterior, posterior, medial, or lateral angulations as well as a series of standard images without any tilt in mandibular position were taken. Vertical distances between the alveolar crest and the superior border of the inferior alveolar canal were measured in posterior mandible and the vertical distances between the alveolar crest and inferior rim were measured in anterior mandible in 12 sites of tomograms. Each bone was then sectioned through the places marked with a radiopaque object. The radiographic values were compared with the real conditions. Repeat measure ANOVA was used to analyze the data. The findings of this study showed that there was significant statistical difference between standard position and 15° posteroanterior tilt [P<0.001]. Also there was significant statistical difference between standard position and 10° lateral tilt [P<0.008], 15° tilt [P<0.001], and 20° upward tilt [P<0.001]. In standard mandibular position with no tilt, the mean exact error was the same in all regions [0.22 +/- 0.19 mm] except the premolar region which the mean exact error was calculated as 0.44 +/- 0.19 mm. The most mean exact error among various postroanterior tilts was seen in 20° lower tilt in the canine region [1 +/- 0.88 mm] and for various mediolateral tilts the most exact error was seen in the canine region in 20° upper tilt [2.9 +/- 2 mm]. The mean exact errors in various regions and various 5° to 20° posteroanterior and mediolateral mandibular tilts were in the range of acceptable values [=1 mm] except for the canine region. However, this effect is more considerable in mediolateral tilt compared with posteroanterior tilt, posterior region compared with anterior region, and upper tilt compared with lower tilt

[ accuracy of linear tomography in mandibular width determination in superior border of mandibular canal]

Finding an accurate and inexpensive method in measurement of bone width for determination of implant size is critical. Linear tomography is a cost effective method and there is no accurate finding about accuracy of linear tomography in evaluation of mandibular wide. The purpose of this study was to determine the accuracy of linear tomography in estimation of mandibular width. In this diagnostic study [estimation of one method], 23 sites of four dry mandibles were selected and marked at the crest with a metal ball markers. After linear tomography in these sites, the width of mandible in the superior border of inferior alveolar canal was measured. The mandibles were then sectioned. The Pearson's rank order correlation coefficient between linear tomography and real values was determined. Then with estimation of mean absolute differences by magnification factor, the percentages of errors in +/- 1mm error limits were determined. The regression equation was written for better determination of agreement rate between radiographic and real values. The percentages of errors in +/- 1 mm error limits were determined. The Pearson's rank order correlation coefficient between the linear tomography and real values was 0.813 [P<0.0001]. The mean absolute differences between the mandibular width in tomographic sections and real values was 0.3 mm [SD=1.13] and 56.5% of width measurements were within the +/- 1mm error limits. By the resulting linear regression equation 51.8% of tomographic values were located within the +/- 1mm error limits. Linear tomography in evaluation of mandibular width should be used more cautiously