Comparison of Microleakage of CEM Cement Apical Plug in Different Powder/ Liquid Ratio in Immature Teeth Using Fluid Filtration Technique.

STATEMENT OF THE PROBLEM: Sealing ability is one of the most important factors for successful endodontic treatment. Some studies have shown that the powder to liquid ratio can influence the properties of dental materials. Subsequently, this may happen for those used for sealing in endodontics. PURPOSE: The purpose of this research was to assess the microleakage of calcium-enriched mixture (CEM) cement apical plug in different powder to liquid ratio. MATERIALS AND METHOD: Ninety-six extracted human single root and single canal teeth were decoronated. Working length was determined using ≠15 k-file. Canal preparation was performed using step back method. Samples were divided into 3 groups randomly. CEM cement was placed into the canal with 1.13, 2.27 and 3.40 powder to liquid ratio in the group 1, 2 and 3, respectively. After complete setting of CEM cement, the micro leakage value was evaluated using fluid filtration method. Data were analyzed using ANOVA and Scheffe tests. RESULTS: The bubble movement in three groups showed a statistically significant difference (p< 0.001). Minimum and maximum bubble movements were observed in the group with powder to liquid ratios of 3.40 and 1.13 respectively. CONCLUSION: Increased CEM Cement powder to liquid ratio will increase the sealing ability of this material as apical plug. Considering the conditions of this study, the powder to liquid ratio of 3:40 provided the best sealing ability.

Evaluating the Accuracy of Two Microleakage Assessment Methods for Mineral Trioxide Aggregate and Calcium-enriched Mixture Cement.

INTRODUCTION: Multiple methods for evaluating microleakage have been introduced over the years, but there has been no agreement as to which technique will give more accurate results. The aim of this study was to compare the accuracy and results of fluid filtration and marginal adaptation methods for mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement apical plugs. METHODS AND MATERIALS: A total of 250 single-rooted human teeth were collected. The teeth were decoronated, the root canals were prepared and open apex condition was stimulated by passing #1 to 4 Peeso Reamer drills from apical foramen. Five teeth were selected as the positive and negative controls and the rest of the samples were randomly allocated to two groups of MTA and CEM cement plugs. In each group, apical plug was placed into the canal. After the apical plugs were completely set, microleakage and marginal adaptation of the samples were evaluated using fluid filtration method and scanning electron microscopy (SEM), respectively. The obtained results were analyzed by independent-samples t test. RESULTS: Gap between plug and dentin walls and air bubbles displacement was higher in MTA group compared to the CEM cement group, though this difference between MTA group and CEM cement group was not statistically significant. Conclusion: According to the obtained results, it seems that there is a direct relationship between the two methods of microleakage assessment.

Diagnostic value of cone-beam computed tomography and periapical radiography in detection of vertical root fracture.

INTRODUCTION: Vertical root fracture (VRF) is the longitudinal fracture of the root in endodontically treated teeth. Considering the limitations of two-dimensional radiographic images in detection of VRF and introduction of cone-beam computed tomography (CBCT), this study was designed to find the sensitivity, specificity and accuracy of CBCT and periapical (PA) radiography in detection of VRFs. METHODS AND MATERIALS: This was a cross-sectional in vitro study on 80 extracted human single canal teeth including 40 maxillary and 40 mandibular teeth. After standardized endodontic treatment of the roots, VRF was induced in half of the teeth in each group, and other half were left without fracture. Teeth were inserted in dry maxillary and mandibular alveoli. PA radiographs and CBCT images were taken from the specimens. Data were analyzed with SPSS software. The McNemar test was used to evaluate the sensitivity, specificity and accuracy of images, and kappa coefficient was used to assess the degree of agreement between the observers. The level of significance was set at 0.05. RESULTS: Sensitivity and specificity values of CBCT were 97.5% and 95%, respectively. However, for PA radiography the sensitivity and specificity were 67.5% and 92.5%, in order of appearance. Accuracy of CBCT (96.25%) and PA radiography (80%) in both jaws were significantly different (P=0.022). Two methods were not significantly different when testing specificity (P=0.298). CONCLUSION: This study showed that the sensitivity and accuracy of CBCT in detection of vertical root fracture are higher than periapical radiography. CBCT can be recommended to be used in detection of vertical root fractures.

Depression and general anxiety in the prisoner of war's children: a cross sectional study.

BACKGROUND: The main aim of this study was to assess the prevalence of depression and general anxiety of the prisoners of war (POW) children. The study was also designed to compare the prevalence of depression and general anxiety amongst the POW's children and normal adults, 20 years after the Iraq-Iran war. METHOD: An analytic cross-sectional study carried out in June 2009 in Yazd (the centre of Yazd province in Iran). The target and sampled population were the children of the Iranian POW who lived in Yazd. One hundred and twenty six POW's children, who were born before 1990 (date of father's freedom) were assessed. The duration of father's captivation was between 29-119 months. Ninety-five subjects accepted to participate. General anxiety and major depression were assessed by Persian version of Hamilton Scale for anxiety and Beck depression Inventory. This study was a combination of the psychological interview and questionnaire. Ninety five of normal adult group were also paired matched and assessed. RESULT: Among 126 POW's children who fulfilled the inclusion criteria, the responsive rate was 75.3% (95 participants). The mean age of participants was 28.3 (SD: 5.34).The father's captivation duration were 29-119 months (mean: 79.2, SD: 21.6). The prevalence of depression and general anxiety amongst the POW's children were 48.4% and 79%. The prevalence of depression and general anxiety among the paired group were 21.1% and 63.2%.The differences between two groups were significant (p =0.000). CONCLUSION: In this study we have demonstrated the prevalence of major depression and general anxiety in POW's children and a normal adult sample. The differences of major depression and general anxiety among the two groups were significant.

Electrically switchable holographic liquid crystal/polymer Fresnel lens using a Michelson interferometer.

A holographic technique for fabricating an electrically switchable liquid crystal/polymer composite Fresnel lens is reported. A Michelson interferometer is used to produce the required Fresnel pattern, by placing a convex lens into one path of the interferometer. Simplicity of the method and the possibility of fabricating different focal length lenses in a single arrangement are advantages of the method. The performance of the fabricated lens was demonstrated and its electro-optical properties were investigated for its primary focal length.