Comparison of Microleakage of Mineral Trioxide Aggregate Apical Plug Applied by the Manual Technique and Indirect Use of Ultrasonic with Different Powers.

STATEMENT OF THE PROBLEM: A mineral trioxide aggregate (MTA) apical plug is commonly applied prior to endodontic treatment of open-apex teeth. However, difficult application and condensation of MTA in the apical region is a drawback of this technique. PURPOSE: This study aimed to compare the microleakage of MTA apical plug applied by the manual technique and indirect use of ultrasonic with different powers. MATERIALS AND METHOD: In this in vitro, experimental study, divergent open apices were created in 48 single-rooted, single-canal teeth using ProFile. The teeth were randomly divided into four experimental groups (n=10). All groups received 5-mm thick MTA apical plug at the apical region using one of the following methods. In group 1, MTA was manually condensed while in groups 2-4, indirect ultrasonic energy with minimum, medium, and maximum power levels was used for MTA plug condensation. After setting of MTA, the apical microleakage of the MTA plug was quantified using the fluid filtration method. Data were analyzed using the Mann-Whitney and Kruskal-Wallis tests (p< 0.05). RESULTS: Significant differences were noted in microleakage of MTA plug between the manual group and ultrasonic groups with medium (p= 0.043) and maximum (p= 0.029) power levels. No significant difference was noted in microleakage of other groups (p> 0.05). CONCLUSION: Considering the current results, it seems that application of MTA with indirect ultrasonic energy at medium or high power level would decrease the microleakage of MTA plug in open-apex root canals.

Allometrically scaled explosive strength, but not static strength or maximal oxygen uptake is associated with better central processing time in young males.

BACKGROUND: We aimed to examine the associations of cardiorespiratory fitness (CRF), static strength and explosive strength with cognitive functions in young males. METHODS: Eighty-six young males (age 16-24 years) participated in the study and took part in a number of tests including: static strength (grip strength test), explosive strength (Sargent jump test), and CRF (via direct measure of maximal oxygen uptake [VO2max]). Static strength and explosive strength were scaled by allometrically modeled skeletal muscle mass (SMM) and height while VO2max was scaled by SMM and body mass (BM). Cognition was assessed by inhibitory control, simple and choice reaction time tasks using computerized Cambridge Neuropsychological Test Battery (CANTAB). Central processing time was measured by surface electromyography changes in isometric contraction response to an audio stimulus. RESULTS: VO2max scaled by BM (but not SMM), was associated with better central processing time and stop-signal reaction time (SSRT). Explosive strength was also associated with better central processing time independent of VO2max. However, static strength was not associated with cognition. CONCLUSIONS: The results suggest that explosive strength is a better predictor of central processing than static strength or VO2max in young males. Longitudinal studies are needed to examine whether explosive strength training in youth would improve central processing time.

Impact of obesity on central processing time rather than overall reaction time in young adult men.

BACKGROUND AND PURPOSE: The association between weight status with simple cognitive tasks such as reaction time (RT) may not be observed in young people as cognitive functioning development has reached its peak. In the present study, we aimed to examine the association between overall and central adiposity with overall and central processing of RT in a sample of young adult men with different weight status from Ardabil, Iran. METHODS: Eighty-six young males between June-July 2018 completed RT tests as well as premotor time (PMT) using surface electromyography changes in isometric contraction response to an audio stimulus. RESULTS: No significant associations were observed between RT and PMT and different body mass index categories (underweight, normal weight, overweight and obese), as well as fat mass and fat to skeletal muscle mass ratio quartiles (Q). However, participants with greater waist to height ratio (WHtR) had longer PMT (but not RT) than their peers with lower WHtR (Q3 than Q2 and Q1 groups; p < 0.05, d = 1.23). Participants in the skeletal muscle mass quartile Q2 tended to have longer RT than participants in Q3 in an adjusted comparison model (p = 0.05, d = 0.72). CONCLUSIONS: Although the association between weight status and RT might be elusive in young adults, our results show that higher central adiposity is negatively associated with PMT in young adults. Longitudinal studies are needed to explore the changes in obesity indexes and process speed in longer terms. LEVEL OF EVIDENCE: Level I, experimental study.

Association Between Weight Status and Executive Function in Young Adults.

Background and objectives: To explore the association between weight status and executive function in young adults. Materials and Methods: Ninety-seven young males (age 17-26 years) underwent adiposity and body composition measurements using body composition analyzer. Inhibitory control and working memory were measured using the Cambridge Neuropsychological Test Battery (CANTAB). Results: Multiple linear regression using both unadjusted and adjusted analyses revealed no association between adiposity and body composition variables with executive tasks, apart from a significant association between skeletal muscle mass (SMM) and mean reaction time on go trial (standardized B = -0.28; p = 0.02). Multivariate analysis of covariance (MANCOVA) revealed that underweight participants presented inferior working memory compared to their normal weight (p = 0.001) or overweight peers (p = 0.008). However, according to the percentage fat quartiles (Q) participants with the highest quartile (Q4) were inferior in inhibitory control than their peers with Q2 (p = 0.04), and participants with the lowest quartile (Q1) were inferior in working memory compared with their peers with Q2 (p = 0.01) or Q3 (p = 0.02). A worse inhibitory control was observed for participants with the highest fat/SMM (Q4) compared to participants in Q3 (p = 0.03), and in contrast worse working memory was observed for participants with the lowest fat/SMM (Q1) compared to participants in Q2 (p = 0.04) or Q3 (p = 0.009). Conclusions: Low adiposity is associated with worse working memory, whereas high adiposity is associated with worse inhibitory control. Therefore, our findings show that normal adiposity, but greater SMM may have a positive impact on executive function in young adults.

Crosslinked Graft Copolymer of Methacrylic Acid and Gelatin as a Novel Hydrogel with pH-Responsiveness Properties.

In this paper, a novel gelatin-based hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto gelatin, using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for hydrogel formation was suggested and the structure of the product was established using FTIR spectroscopy and gravimetric analysis of the products. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA/DTG). The effect of reaction variables such as concentration of APS and MBA were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The gelatin-g-PMAA hydrogel exhibited a pH-responsiveness character so that a swelling-deswelling pulsatile behavior was recorded at pHs 2 and 8. This on-off switching behavior makes the hydrogel as a good candidate for controlled delivery of bioactive agents.