ABSTRACT
Objectives: This study aimed to determine the prevalence of class I, II, and III integrons among clinical Acinetobacter baumannii isolates collected from hospitalized patients
Methods: This cross-sectional study was conducted at two teaching hospitals in Isfahan, Iran, from October 2015 to October 2016. A total of 147 non-duplicate A. baumannii isolates were collected from clinical specimens and identified as A. baumannii using standard microbiological methods and confirmed by genotyping. Antimicrobial susceptibility was determined using disc diffusion method, and the presence of integron genes was performed using the polymerase chain reaction
Results: Out of 147 confirmed A. baumannii isolates, 97.3% of isolates were extensive drug-resistant [XDR] and 2.7% were multidrug-resistant [MDR]. Class I and II integrons were detected in 63.9% and 78.2% of the A. baumannii, respectively. Class III integron was not detected in any of the isolates
Conclusion: Our results show a high prevalence of classes I and II integrons which may play a key role in the acquisition of MDR and XDR phenotype among A. baumannii isolates in our region. Therefore, use of appropriate infection control in clinical settings and implementation of treatment strategies is necessary for our hospitals
ABSTRACT
Many studies have been performed to evaluate the stress distribution around endodontic posts; those which compared posts composed of different materials are rare. The aim of this study was to compare stresses induced in dentin by three structurally different posts using photoelasticity method. Nine blocks of PSM-5 Photoelastic material with 45x45x10 mm dimension were prepared. In each block, a canal 9 mm in length and 0.8 mm in width was drilled. Blocks were divided into 3 groups of three each. In the first group, the canals were prepared for insertion of Fiber Post with 1.25 mm width. In the second group, the canals were prepared for insertion of ParaPost with 1.25 mm width and the canals in the third group were prepared for casting post similar to the above samples. Casting Post pattern was made by Duralay resin and casted by Ni-Cr alloy. All posts were cemented in canals with Panavia cement. The stresses were evaluated in the polariscope under three different conditions: 1] without load, 2] with 135 N vertical load, and 3] with 90 N oblique load [26° inclination to post long axis]. The fringe orders in the cervical, middle and apical regions of the posts were evaluated and compared with each other. Application of the vertical load induced a high stress concentration [FO=4] in the apical region of the ParaPost, while lower stress was observed in the middle [FO=2] and cervical region[FO=2+]. Fiber Post and Casting Post showed even stress distribution [FO=2+]. High stress concentration was detected with the application of oblique force in the cervical region of ParaPost [FO=5] and Casting Post [FO=3+]. Fiber Posts fractured before reaching 90-N loading force. The stress distribution around Fiber Post and Casting Post were constant in comparison with ParaPost. Fiber Post with 1.25 mm width was not recommended in situations with high oblique Stresses
ABSTRACT
The resistance to fracture of endodontically treated teeth restored with esthetic post systems has not been extensively researched. This in vitro study compared the fracture patterns of endodontically treated teeth with esthetic post systems with different analysis methods. A total of 26 recently extracted human maxillary central incisors were decoronated and then endodontically treated. Teeth were restored with quartz fiber posts. All posts were cemented with Panavia dual curing adhesive resin cement and subsequently restored with composite cores. Three methods were used to test fracture resistance. Each specimen was embedded in acrylic resin and then secured in a universal load-testing machine. A compressive load was applied at 135° degree angle at a crosshead speed of 1 mm/min to the long axis of the tooth until fracture occurred. The two other methods, finite element analysis [FEA] and photo elastic study used the same angulation and 90 N force to simulate the first method. The data were then compared. Clinical results indicated that fracture was most likely to occur between core and dentin, and then in the cervical 1/3 of the root. Photo elastic study demonstrated similar results; the highest stresses occurred at the junction of dentin and core contralateral to the side where force was applied. FEA also confirmed these results; however it also showed that the highest stresses arise at the dentin/core junction contralateral to the force point. All three techniques reiterate that the risk of fracture is greatest at the cervical dentin/COre junction