Apical extrusion of intracanal bacteria following use of various instrumentation techniques.

AIM: To evaluate the number of bacteria extruded apically from extracted teeth ex vivo after canal instrumentation using a manual technique and three engine-driven techniques utilizing nickel-titanium instruments (K3, RaCe, and FlexMaster). METHODOLOGY: Seventy extracted human mandibular premolar teeth with similar dimensions were used. Access cavities were prepared and root canals were then contaminated with a suspension of Enterococcus faecalis and then dried. The contaminated roots were divided into four experimental groups of 15 teeth each and one control group of 10 teeth. G1. RaCe group: the root canals were instrumented using RaCe instruments. G2. K3 group: the root canals were instrumented using K3 instruments. G3. FlexMaster group: the root canals were instrumented using FlexMaster instruments. G4. Manual technique group: the root canals were instrumented using K-type stainless steel instruments. G5. CONTROL GROUP: no instrumentation was attempted. Bacteria extruded from the apical foramen during instrumentation were collected into vials. The resultant microbiological samples were removed from the vials and then incubated in culture media for 24 h. The number of colony-forming units (CFU) was determined for each sample. The data obtained were analysed using the Kruskal-Wallis one-way analysis of variance and Mann-Whitney U-tests, with alpha = 0.05 as the level for statistical significance. RESULTS: There was a significant difference between experimental-control and engine-driven-manual technique groups (P < 0.05). The manual technique was associated with the greatest extrusion of microorganism. CONCLUSIONS: All instrumentation techniques extruded intracanal bacteria apically. No significant difference was found in the number of CFU among the engine-driven techniques; manual techniques extruded significantly more microorganisms.

Improvement of the predictive value of CD4+ lymphocyte count by beta 2-microglobulin, immunoglobulin A and erythrocyte sedimentation rate. The Multicentre Cohort Study Group.

OBJECTIVE: To evaluate whether the use of immunological markers in addition to CD4+ lymphocyte count can improve the prediction of the probability of developing AIDS within a given period. DESIGN AND SETTING: Prospective multicentre cohort study of homosexual men. PATIENTS: A total of 447 HIV-positive homosexual men followed prospectively at 6-month intervals (median time of observation, 47 months). METHODS: Estimation of AIDS-free time using lifetable plots by Cutler and Ederer and Weibull parametric models. A stepwise multivariate regression analysis was used to calculate the optimal combination of the parameters studied. RESULTS: In general CD4+ lymphocyte counts are most important for the prediction of AIDS-free time. The use of serum levels of beta 2-microglobulin (beta 2M), immunoglobulin A (IgA) and erythrocyte sedimentation rate (ESR) can significantly improve the predictive value of CD4+ lymphocyte counts. However, the usefulness of these parameters depends on the stage of HIV disease. In patients with a CD4+ lymphocyte count > 500 x 10(6)/l, only IgA level had a significant predictive value; none of the other parameters significantly improved the model. In patients with a CD4+ lymphocyte count < 500 x 10(6)/l, the absolute number of CD4+ cells itself was the most important single predictive parameter, but the prediction of AIDS was significantly improved by the addition of the other parameters investigated. The most powerful combination of parameters in this group was CD4+ count, beta 2M and ESR. CONCLUSION: Determination of serum IgA, beta 2M and ESR in addition to CD4+ lymphocyte count may aid the choice of specific therapeutic regimens or systems of care for HIV-positive individuals.

The effect of preparation conditions of acrylic denture base materials on the level of residual monomer, mechanical properties and water absorption.

OBJECTIVES AND METHODS: The curing of several commercial powder/liquid mixtures of acrylic denture base materials was carried out at different temperatures and curing times. The levels of residual monomer, tensile strength, percentage elongation before break and water absorption were measured. RESULTS AND CONCLUSION: It was found that the level of residual monomer determined by gas-liquid chromatography decreased with curing time and temperature increase. At the same time, the tensile strength was improved and water absorption decreased.

Color stability of different denture teeth materials: an in vitro study.

The aim of this in vitro study was to compare the color stability of commercially available porcelain, reinforced acrylic, and conventional acrylic denture teeth materials used in removable prostheses. Two brands of porcelain (Unilux-Enta Lactona-Holland and Vivoperl-Ivoclar-Liechtenstein), 2 brands of reinforced acrylic (Optodent-Bayer-Germany and Ivolek-Ivoclar-Liechtenstein), and 2 brands of conventional acrylic (Isodent-Güney Dis Deposu-Turkey and Samed-Turkey), were made, for a total of 6 different denture teeth groups. Denture teeth were subjected to 3 staining solutions (filtered coffee, tea, and cola) and distilled water. From each group of denture teeth, 4 sets of maxillary anterior denture teeth were immersed in each of the 4 solutions. The color values of denture teeth were measured colorimetrically with the Gardner XL 20 Tristimulus Colorimeter (Gardner Lab. Inc., Bethesda, Maryland, USA). Color changes were characterized in the CIEL*a*b* color space. Color change values were determined after 1 day, 1 week, 2 weeks, and 4 weeks. The color difference values were calculated and then evaluated by two-way ANOVA statistically. The filtered coffee solution was found to be more chromogenic than the other 2 staining solutions, while porcelain denture teeth materials were more color stable. Assuming the color change of deltaE* < 1.0 as a discernible limit and deltaE* = 3.3 as an acceptable value, the filtered coffee, tea, and cola had slight staining effects on all 6 groups of denture teeth.

High-level sensitivity of quantitative pp65 cytomegalovirus (CMV) antigenemia assay for diagnosis of CMV disease in AIDS patients and follow-up.

Cytomegalovirus (CMV) antigenemia was evaluated in 174 patients positive for human immunodeficiency virus. Antigenemia could be detected in 96.7% of patients with CMV disease, 76.9% of patients suffering from a relapse of the disease, and 11.4% of asymptomatic patients with CD4 levels of < 100 cells per microliter. No antigenemia was detected in patients with CD4 levels of 250 to 500 cells per microliter. Specificity and the positive predictive value for CMV disease were increased only if more than 5 positive cells per slide were considered. However, CMV disease may also occur in patients with low-grade antigenemia.