Evaluation of the effect of different glass fiber post lengths on fracture resistance of endodontically treated central incisors

Use of glass fiber posts is of widespread acceptance in restoring root canal treated teeth, but studies concerning the most proper length of the post to provide the utmost fracture resistance are inadequate. The aim of this study was to evaluate the effect of glass fiber post length on fracture resistance of root canal treated central incisors. This experimental study was carried out on 40 maxillary central incisors in 4 groups of 10 each. RDT posts and cement was used in this experimental study with the lengths of 6, 8, 10, and 12 mm in the study groups. The samples were debrided and decoronated at the CEJ levels and endodontically treated using step-back technique. RDT drills were used for post space preparation. Then, the root canal walls were etched and the posts cemented in place. The composite cores were then prepared at the height of 5 mm and samples mounted 2mm down to their CEJ levels within acrylic blocks. An impression material [Impregum, 3M, ESPE] with a thickness of 0.2mm was used to simulate PDL around the samples. The samples were subjected to compressive forces at a 135-degree angle to their long axes using a Universal Testing Machine. Data pertaining to the fracture of the samples were analyzed using ANOVA and Tukey statistical tests. The maximum resistance to fracture was recorded in 8-and 10-mm-long posts and the minimum was observed in the lengths of 6 and 12 mm. Statistical tests showed a significant difference between 8- and 10-mm-long posts with those having lengths of 6 and 12 mm in terms of fracture resistance. There was no significant difference between 8- and 10-mm-long posts as well as 6- and 12-mm-long ones. It can be concluded that the length of post is influential in the fracture resistance of the root so that the maximal resistance can be obtained in 8 to 10 mm of length and such lengths can be recommended for non-metal posts

[Comparison of glaze or polish on dental porcelain's surface roughness]

Surface roughness of dental restorations can reduce the biological properties and wear the opposite. The goal of this investigation was comparing these process effects on the surface roughness of porcelain. In this experimental study, 20 Noritake porcelain disks of 1 cm diameter and 2-2.5 mm thickness with non-percious metal base were fabricated. All samples were finished with medium grit silicone disk and then randomly divided into four groups [n=5]. In the first group, the samples were self glazed. In the second group, the samples were polished [EVE Polisher Kit]. In the third group, after self glazing with a coarse grit stone, the self glaze layer was omitted, then reglazed. The fourth group was similar to the third group, but in the end stage a polishing kit was used. Samples were evaluated with Profilometer and then with SEM. As a result of normal distribution of the data, One-Way analysis of variance [ANOVA] was used for statistical analysis. The mean roughness for the glazed group was 1.06 +/- 0.0547; the polished group, 0.92 +/- 0.1304; the reglazed group, 1.22 +/- 1304; and the polished after glaze group 1.14 +/- 0.1342. The polished and polished after glaze groups had a round shape in 100%, but the glazed and reglazed groups had a sharp shape in 60%. The polished surface is less rough compared to the glazed surface and in the polish after glaze group, the surface of the porcelain is less rough compared to the reglaze group

[Evaluation of three cement type on FRC post retention]

One of the challenges of restoring endodontically treated teeth with fiber reinforced composite [FRC] posts is their debonding from root canal dentin. Different factors such as cement type, effect the post retention. According to the controversies in this regard, this study aimed to evaluate the effect of three luting cements on retention of FRC posts in the root canal. In this in-vitro study 30 selected root canal treated premolar teeth were randomly allocated to three experimental groups. After post space preparation, RTD fiber posts, with 10mm length and 2 mm diameter, were cemented in the canal with one of the following luting agents: zinc phosphate [Harvard], Glass-Ionomer [GC] and resin cement Maxcem [Kerr]. They were then fixed and force was applied using Instron 5500 machine. The Data was subjected to ANOVA for statistical analysis. The observed retention in studied groups was as follows: resin cement 127 +/- 18.5 [MPa], zinc phosphate 102 +/- 29.7 [MPa] and glass-ionomer 51 +/- 14.8 [MPa]. In order to increase the retention of FRC posts, cementation with resin cements is recommended

Effects of sub-inhibitory concentrations of essential oils of Mentha spicata and Cumminum cyminum on virulence factors of Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of important opportunistic pathogen, that cases serious infections. It produces many virulence factors, and this bacterium usually is resistance against antimicrobial agents. The aim of this study was evaluate the effects of sub-MICs of essential oils of Mentha spicata and Cumminum cyminum on alginate production, biofilm formation, swimming, twitching and adhesion in P. aeruginosa 8821M. Minimal inhibitory concentrations [MIC] of essential oils of Mentha spicata and Cumminum cyminum were determined by macrodilution method. Alginate production, biofilm formation, swimming, twitching and adhesion in the present of sub-MICs [1/2, 1/4 and 1/8 MIC] of essential oils were determined in mucoid P. aeruginosa 8821M and compared with controls. The MICs of essential oils against P. aeruginosa for M. spicata and C. cyminum oils were obtained 16 and 32 micro g/ml respectively. The results show that all oils at 1/2 and 1/4 MICs were significantly reduced all tested virulence factors. At 1/8 MICs, M. spicata had effect just on adhesion but C. cyminum had effect on Alginate production, biofilm formation, swimming and twitching. This study showed that sub-MIC levels of M. spicata and C. cyminum essential oils affected alginate production, biofilm formation, swimming, twitching and adhesion in P. aeruginosa 8821M and it is probable to use of these medicinal plants for treating

[Prevalence of anti-HCV antibody and related risk factors among bleeding disorder patients in Yazd province of Iran]

Inherited bleeding disorder is a disease due to deficiency in clotting factors or platelets. Replacement therapy of unscreened blood and blood products or unviricidal concentrated clotting factors would expose these patients to risk of acquired hepatitis C. The aim of this study was to determine the seroprevalence of hepatitis C virus and related risk factors among bleeding disorder patients in Yazd province. This cross-sectional study was performed in Yazd province in summer 2006 using census method. Following data collection through questionnaires, blood samples were taken from 77 [82.8%] patients. Plasma samples were tested for the presence of anti-HCV antibody via a third-generation ELISA kit. To exclude false positive cases, ELISA positive samples were re-tested by the confirmatory third generation RIBA test. The assessment of risk factors was done from the information analysis of both the questionnaires and test results by Chi-square test and multivariate logistic regression analysis, using SPSS 11.5 statistic software. The frequency of anti-HCV antibody was found in 38 [49.4%] patients. Chi-square test showed a statistically significant relationship between the severe form of the disease [in terms of blood products needed] [P<0.001], treatment duration of more than 121 months [P<0.001] and family history to HCV [P<0.05] antibody positivity. Successful execution of the screening of the blood and blood products as well as more scrutiny in preparing concentrated factors have been led to a remarkable decrease in the new infections among the recipients of these products in Yazd province

Frequency of Helicobacter pylori vacA genotypes in Iranian patients with gastric and duodenal ulcer

Helicobacter pylori infection is a risk factor for developing chronic peptic ulcers and gastric cancer. The purpose of this study was to investigate the frequency of Helicobacter pylori vacA genotypes in patients with gastric and duodenal ulcer. A total of 100 biopsy specimens of patients with gastric [n = 50] and duodenal [n = 50] ulcer were collected. The specimens were cultured on selective media and incubated in a microaerophilic atmosphere at 37°C for 5-10 days. The isolates were characterized to species level by conventional biochemical tests. The extracted DNA from isolates was used to perform a polymerase chain reaction based, simultaneous analysis of the cagA status, allelic variation of the signal regions [s1, s2] and the middle regions [m1, m2] of the vacA gene. H. pylori isolated from 50 specimens of patients and the vacA gene was detected in all isolates. Among vacA genotypes the s1/m1 was the most common in H. pylori isolates from patients with gastric ulcer [56%] and duodenal ulcer [68%]. This study demonstrated that vacA slml is common genotype of H. pylori in patients with peptic ulcer and the vacA allele s1 of this bacterium is associated with ulcer

Effect of ferrule on fracture resistance in endodontically treated teeth that were restored with bonded posts and cores

A dowel in an endodontically treated tooth could transfer occlusal forces intraradicularly which may increase the vertical root fracture susceptibility. Ferrule is one of the methods by which tooth structure can be reinforced. Thirty freshly extracted central incisors were endodontically treated. The teeth were randomly divided into two groups. Those in the control group were treated using prefabricated post and composite core [with no ferrule], and the teeth in test group were treated with similar prefabricated posts and cores while having two mm ferrule height. All teeth were restored with full metal crowns. The specimens were mounted on a universal testing machine and a compressive load was applied to the long axis of the teeth until fracture occurred. There was a significant difference between the ferrule and non-ferrule groups [P < 0.000]. The mean for ferrule group was 584N, while this value was 194N in non-ferrule group. The ferrule effect increases the fracture resistance of endodontically treated teeth that are restored with bonded post and cores

[ prevalence and molecular characterization of vancomycin resistant gram positive cocci isolated from patients in Tehran]

Gram positive bacteria, particularly, Staphylococcus aureus, coagulase negative staphylococci and enterococci are of particular concern in hospitals. But there has been increasing concern about the development of vancomycin resistant enterococci and MRSA strains with reduced susceptibility to vancomycin over the last decade. Therefore, the present study was carried out to confirm the identification of vancomycin resistant gram positive cocci, to determine antibiotic resistance pattern and to study vancomycin resistance genes. The isolates from clinical samples were collected from hospitalized patients and outpatients in Tehran. Gram positive cocci species identification was performed by using conventional tests and PCR using specific primers. VRE isolates were subjected to antibiotic susceptibility testing, MICs of vancomycin were determined by the E-test method. Determination of vancomycin resistance genes, vanA and vanB were performed with PCR. Confirmation of transposons was performed with specific primers for vanS. Out of 1030 gram positive isolates, none of the staphylococci or streptococci isolates were resistant to vancomycin. Most of vancomycin resistant isolates in this study were VRE. faecium [96%] and harbored vanA. All of the isolates were positive for vanS the conserved fragment of transposon and carried the identical digestion pattern like type strain. According to the results of this study, all of the vancomycin resistant isolates were enterococcus spp. Vancomycin resistant enterococci itself is now a major and largely untreatable infection, and can pass the vancomycin resistance genes to the other highly virulent gram positive cocci

prevalence of obligatory anaerobic bacteria in oral cavity infections

Many infections of the oral cavity and adjacent structures involve anaerobic bacteria. Most infections involve multiple anaerobes and in many instances facultative organisms. Present study was conducted regarding to clinical aspects and complications of anaerobic bacterial infections in oral cavity. 72 Specimens were taken from oral cavity infections. Routine culture techniques and strict anaerobic techniques were used for isolation and identification of aerobic, facultative and obligatory anaerobic bacteria respectively. Cultures of all specimens were positive. Mono- bacterial and poly bacterial infections were repored in 1/3 and 2/3 of specimens, respectively. More than 65% of isolated organisms, were obligatory anaerobic belonging to the Peptostreptococcus, Prevotella, Fusobacterium Porphyromonas and Bacteriodes as well as facultative and aerobic species include Streptococcus, Staphylococcus interobacteriacea and Actinomes Israelii are also obtained. Many infections of the oral cavity and adjacent structures involve obligatory anaerobic bacteria. Regarding to results of present study, under the anaerobic atmospheric system, obligatory anaerobic bacteria were isolated and identified from clinical specimens of oral cavity infections, especially abscesses

Prevalence of clostridium difficile- associated diarrhean in hospitalized patients with nosocomial diarrhea

Clostridium difficile is a frequently identified cause of nosocomial gastrointestinal disease. It has been proved to be a causative agent in antibiotic-associated diarrhea, antibiotic-associated colitis, and pseudomembraneous colitis. This study was aimed to determine the prevalence of C.difficile- associated diarrhea in hospitalized patients with nosocomial diarrhea. The 942 hospitalized patients stool samples with nosocomial diarrhea were collected at three hospitals in Tehran from Dec 2002 to Feb 2004.All the stool samples were cultured and in 97 [prevalence: 10.9%] samples grew C.difficile that 57 [prevalence: 6.1%] isolates were toxigenic by cytotoxicity assay and so 57 patients had C.difficile- associated diarrhea. Results of statistical analysis showed significant difference between the rate of C.difficile associated diarrhea and the patients ages [P<0.05]

Study of tuberculous infection rate in townships in a Centeral Province of Iran

Tuberculosis is a continuous threat for health in all parts of the world. An estimated one-third of the world' s population is infected with the Mycobacterium tuberculosis and 7 to 8 million people develop TB disease each year. The purpose of this study was to investigate the rate of tuberculosis in the townships of Yazd province, Iran. During the study period [19971999], 3885 suspected tuberculosis patients [1820 males and 2065 females; aged 8-85 years] who had been referred to the Yazd referral polyclinic were investigated by Ziehl Neelsen staining and culture method and questionnaire was completed for each subject. Then, Collected data were analyzed by statistical package for social science [SPSS] and chi-square program. The results show that, of the total suspected tuberculosis, 604 cases were found to be positive for tuberculosis. The average annual rate of tuberculosis was 26.8 cases per 100000 population [23.1/100000 males and 31/100000 females]. The highest and lowest rates of tuberculosis were observed among Sadough [78.1/100000] and Abarkouh townships population [19.8/100000] and also among age group >/= 50 years old [111/100000] and < 10 years old [7/100000], respectively. The average annual rates of pulmonary and extra-pulmonary tuberculosis in Yazd province were 152 cases [20.2%] and 48 cases [6.4%], respectively. It seems that, despite the efforts, which have been done for prevention, diagnosis and treatment of patients with tuberculosis, it is still considered as a threat for health in the Yazd province, Iran

Prevalence of Ureaplasma urealyticum and Mycoplasma genitalium in men with non-gonococcal urethritis

This study in Teheran, Islamic Republic of Iran, investigated the prevalence of Ureaplasma urealyticum and Mycoplasma species in men with non-gonococcal urethritis. Urethral swab samples were collected from 125 cases and 125 healthy men as a control group. The samples were then investigated by culture methods. The rates of detected bacteria in case and control groups were 19.2% and 7.2% for U. urealyticum, 7.2% and 0.8% for M. genitalium, and 2.4% and 1.6% for M. hominis respectively. Statistical analysis showed a significant difference between case and control groups in the prevalence of U. urealyticum and M. genitalium but not M. hominis. It is concluded that in men, U. urealyticum and M. genitalium may have an etiologic role in non-gonococcal urethritis

Selected epidemiological features of human brucellosis in Yazd, Islamic Republic of Iran: 1993-1998

Brucellosis is a significant health problem in countries where control of zoonoses is inadequate. During 1993-98, we analysed sera and cultures from 792 suspected brucellosis patients who presented with histories of fever, chills, night sweating, weakness, malaise and headache to the referral hospital in Yazd. Cases were investigated by tube agglutination test [TAT] and 2-mercaptoethanol test [2-MET] and a questionnaire was completed for each.TAT titre was > / = 1:1 60 for 745 patients [94.1%] and 2-MET was positive for 42 [5.3%]. Of 745 confirmed cases, 460 were from 1996-1997. Prevalence was highest in summer [39.5%] and more common males than among females. Prevalence was highest among those aged 10-19 years [27.7%]. Most patients had a history of infected cheese, milk and milk product consumption [98%]

Enteropathogenic bacteria isolated from specimens of diarrheal children under 5 years old

Acute infectious gastroenteritis is one of the most common infectious diseases of humans in the world. Diarrhea is a significant cause of death in infants. It has been estimated that up to 15% of children in developing nations die of diarrhea before 3 years of age. This study has been carried out to investigate entheropathogenic bacteria from 558 specimens of children less than 5 years of age. The results were obtained as follow: 1-Anaerobic bacteria: Toxigenic [Clostridium difficile 2 cases [3.6%] [Associated with bacterial Toxins] and Enterotoxigenic clostridium per/linens, was not seen. 2- Microaerophilic bacteria: Cainpylobacterjejunj 8 cases [14.5%]. 3- Facultative bacteria: Salmonella Typhimuriuni 4 cases [7.3%] and Salmonella havana 1 case [1.8%]. Shigella dysenreriac 4 cases [7.3%]; Shigella flexneri 8 cases [14.5%]; Shigella boydii 1 case [1.8%] and Shigella sonnei 7 cases [12.7%]. Escherichia coli 13 cases [23.6%]. Yersinia enteroco/jtjca and Vibrio cho/erac were not seen, Aerornonas hydrophila 6 cases [10.9%] and Plesiomonas shigelloides 1 case [1.8%]