Silicon as an attenuator of the toxic effects of aluminum in Schinus terebinthifolius plants.

Aluminum (Al) is highly toxic to plants, since it causes stress and inhibits plant growth. Silicon (Si) is known to mitigate the stress caused by Al in several plant species. Thus, the current study aims to investigate the soothing effects of Si on morphophysiological and photosynthetic variables, and the attributes associated with oxidative stress in Schinus terebinthifolius plants exposed to Al. Treatments have followed a completely randomized design, with three repetitions based on the following Al/Si combinations (in mM): Treatment 1: 0 Al + 0 Si; Treatment 2: 0 Al + 2.5 Si; Treatment 3: 1.85 Al + 0 Si; Treatment 4: 1.85 Al + 2.5 Si; Treatment 5: 3.71 Al + 0 Si; Treatment 6: 3.71 Al + 2.5 Si. Each sampling unit consisted of a tray with 15 plants, totaling forty-five per treatment. Shoot and root morphological variables, photosynthetic variables, photosynthetic pigments, hydrogen peroxide concentration, lipid peroxidation (MDA), guaiacol peroxidase (POD) and superoxide dismutase (SOD) enzymes, and non-enzymatic antioxidant such as Ascorbic acid (AsA) and non-protein thiol (NPSH) concentration were assessed. Root growth inhibition followed by changes in root morphological variables have negatively affected root and shoot biomass production in plants only subjected to Al. However, adding 2.5 mM Si to the treatment has mitigated the toxic effects caused by 1.85 mM of aluminum on S. terebinthifolius plants.

Dentin Optical Density in Molars Subjected to Partial Carious Dentin Removal.

AIM: This study aimed to evaluate changes in the optical density of dentin in primary molars with deep caries three to six months after they were subjected to partial carious dentin removal. STUDY DESIGN: This was a blind controlled, clinical therapy study. Standardized digitalized bitewing radiographs of 42 teeth were analyzed using Adobe Photoshop(®) to quantitatively determine the gray scale of the affected dentin beneath the restoration, in comparison with healthy dentin. A mixed-effects model was used for statistical analysis. The gray tone level was considered a dependent variable; the tooth region and the time, in addition to the interaction between them, were the independent variables. Values of p < 0.05 were significant. RESULTS: During the interval between time zero and three months, the gray tone levels of affected dentin varied from 80.99 ± 3.17 to 98.57 ± 3.17; i.e., an estimated increase of 18 (p < 0.0001). The values for healthy dentin ranged from 118.22 ± 3.17 to 122.02 ± 3.17; i.e., a mean increase of four in the gray tone levels (p = 0.0003). During the interval between three and six months, both healthy and affected dentin showed similar behavior (98.57 ± 3.17 to 103.32 ± 3.20 and 122.02 ± 3.7 to 126.56 ± 3.20, respectively) (p = 0.0001). CONCLUSIONS: Significant increments were observed in the optical density of the affected dentin after three months compared to that of healthy dentin in primary molars treated using the partial carious dentin removal technique.

Enamel defects in the primary dentition of preterm and full-term children.

AIM: This study compared enamel defects in children born prematurely and at term. METHOD: 96 children born at term (G1), and with 96 children born prematurely (G2) were studied. RESULTS: A higher prevalence of enamel defects was found in the premature group, with a predominance of hypoplasia. In G1, 64 teeth displayed enamel defects (51 opacities and 13 hypoplasias). In G2, 110 defective teeth were found, (29 opacities and 81 hypoplasias). A significant correlation was found between very low birth weight (VLBW) and the presence of these defects (p < or = 0.001). The teeth most affected were the incisors, canines and molars. CONCLUSION: Prematurity, in conjunction with other factors, can predispose children to enamel defects.