[Comparison of three root canal preparation techniques on debris extrusion from apical foramen]

Periapical reparative process, following root canal therapy [RCT] depends on various factors, including the amount of extruded debris to periapical region. The amount of debris extrusion is a determining factor in periapical reparative process. The aim of this study was to compare the three debris extrusion from apical foramen in root canal preparation techniques; manual step back, rotary balanced force and rotary crown down. A total number of 60 single rooted teeth [incisor and premolar] were chosen non-randomly and were divided into 3 groups according to foramen diameter, root length, root divergence and the tooth type. The root canals were prepared according to standard techniques and debris extrusion was evaluated according to Montgomery method. The weights of debris were recorded by 10[-5] gram precision. The data were analyzed by SPSS software version 13 using one way ANOVA and Post-Hoc tests. Mean debris weight for the step back, balanced force and crown down techniques were 0.39 +/- 0.21, 0.22 +/- 0.09 and 0.26 +/- 0.12 mg respectively. The difference among three groups was statistically significant [P<0.05]. The difference between the two rotary groups was not significant. Debris extrusion in manual step back technique was more than the rotary balance-force and crown down technique

effects of noise exposure on rat's hematologic parameters and red cell indices

Environmental pollution plays a destructive role in the daily life of industrialized communities and due to their negative impact on the society they are always under close investigation. Besides wellknown pollutants substantial, all major international health organizations consider noise pollution as an important health problem. In this study, we have used an animal model to study the effects of noise exposure on is hematological survey [CBC] and red cell indices. Forty male Winstar rats were randomized into two groups of test and control. Animals in the test group were exposed to a 20 dB unmodulated sinusoidal noise with a frequency of 1100 Hz for 120 days, while animals in the control group were kept in normal condition. By the end of the study, a blood sample was taken from each animal in both groups and a complete blood count was performed. In animals in the test group as compared to those in the control; 1] there was significant [p<0.001] increase in the number of red blood cells, white blood cells, hemoglobin, and hematocrit; 2] there was significant [p<0.001] decrease in mean corpuscular volume [MCV], mean cell hemoglobin [MCH], and mean cell hemoglobin concentration [MCHC]. It was then concluded that noise exposure affects blood cells