Effect of passive ultrasonic agitation during final irrigation on cleaning capacity of hybrid instrumentation

OBJECTIVES: To evaluate the effect of passive ultrasonic agitation on the cleaning capacity of a hybrid instrumentation technique. MATERIALS AND METHODS: Twenty mandibular incisors with mesiodistal-flattened root shape had their crowns sectioned at 1 mm from the cementoenamel junction. Instrumentation was initiated by catheterization with K-type files (Denstply Maillefer) #10, #15, and #20 at 3 mm from the working length. Cervical preparation was performed with Largo bur #1 (Dentsply Maillefer) followed by apical instrumentation with K-type files #15, #20 and #25, and finishing with ProTaper F2 file (Denstply Maillefer). All files were used up to the working length under irrigation with 1 mL of 2.5% sodium hypochlorite (Biodynamica) at each instrument change. At the end of instrumentation, the roots were randomly separated into 2 groups (n = 10). All specimens received final irrigation with 1 mL of 2.5% sodium hypochlorite. The solution remained in the root canals in Group 1 for one minute; and ultrasonic agitation was performed in Group 2 for one minute using a straight tip inserted at 1 mm from working length. The specimens were processed histologically and the sections were analyzed under optic microscope (x64) to quantify debris present in the root canal. RESULTS: The samples submitted to ultrasonic agitation (Group 2) presented significant decrease in the amount of debris in comparison with those of Group 1 (p < 0.05). CONCLUSIONS: The hybrid instrumentation technique associated with passive ultrasonic agitation promoted greater debris removal in the apical third of the root canals.

VARIOUS IN RUNNING PATTERN AND SKELETAL MUSCLE ADAPTATIONS IN VOLUNTARY RUNNING RATS AT DIFFERENT LOAD / 体力科学

The running behavior and muscle characteristics associated with voluntary running activity were studied in female Fischer 344 rats after 9 weeks of training in voluntary exercise wheel cages. The exercise wheel employed allowed a load to be added to the wheel axis. The running activity was recorded as the number of rotations every 10 s for 24 h, and the number of running bouts, running duration, running speed and distance run per day were varied. Addition of a load to the wheel axis allowed the running style to be changed, and reduced the running duration and speed in each bout. The voluntary running training was done with no load, 30% per body weight load, and 60% per body weight load, and as treadmill running (40 m/min, 60 min/day) .<BR>In the voluntary training, a difference in the total running distance was observed with increased load. The total distance run under 0%, 30% and 60% load in the voluntary group was about 552, 475, and 438 km, respectively, after training for 9 weeks. As a result of training, the weights of dorsiflexor muscles tended to increase with treadmill running, whereas weights of plantar-flexor muscles increased significantly in the voluntary training groups. In the plantaris muscle, the cross-sectional area of all fiber types was not changed by treadmill training, but in voluntary training, almost every type of fiber was enlarged. Voluntary running with a 30% load increased the cross-sectional area of type I and type ha fibers in the plantaris muscle compared with no load exercise. However, no significant differences in the cross-sectional area of these fibers were observed between 30% and 60% load exercise. The fatigue tolerance of the plantaris muscle improved significantly in all training groups, and the 60% load group showed the highest value.<BR>These results suggest that voluntary loaded running is more effective for muscle enlargement than treadmill training and/or voluntary training with no load.

Changes in myosin heavy chain isoform composition of rat skeletal muscles as a result of running and jumping trainings / 体力科学

Four myosin heavy chain (MHC) isoforms were detected in rat hind-limb fast muscles. MHC isoforms are particularly good candidates for fiber type-specific markers in myofibril proteins. We studied the effect of running or jumping training on MHC isoform composition in 18, 6 month-old female rats. The animals were divided into three groups : sedentary (S; n=6), running (R; n=5) and jumping (J; n=7) at 4 months of age. Animals in group R were trained with treadmill running (30 m/min, 60 min/day and 5 days/wk) for 8 weeks. Animals in group J were trained with vertical jumping (40 cm high, 100 repetitions/day, 5 days/wk) for 8 weeks.<BR>There was no significant difference in body weight among the groups. Muscle weight and muscle weight/body weight for the plantaris were significantly increased in both trained groups, but there was no significant difference in the protein concentration. With regard to MHC isoform composition, there was no significant difference in the compositions of the type I and type ha MHC isoforms. In the type lid MHC isoform, the values for both trained groups were significantly higher than that of group S (p<0.05) . The values for both trained groups in the type lib MHC isoform were lower than that of group S. In particular, there was a significant difference between groups S and J (p<0.05) .<BR>These results indicate that a relative increment of the type lid MHC isoform is a typical adaptation phenomenon of the olantaris muscle in rats riven runninr and iumoinr training.