Conjugation between 3D and 2D aromaticity: does it really exist? The case of carborane-fused heterocycles.

Although several synthesized icosahedral carborane fused 2D π-ring systems are known, and even considerable conjugation has been noted between them in some cases, the phenomenon itself is not fully understood. Based on the results of our computational study, it can be concluded that the 2D aromatic character of the fused (exo) five-membered ring is low, even in cases where significant conjugation was proposed in previous studies. Moreover, the carborane moiety constricts the bonding properties of the exo ring, thus prohibiting or promoting different Lewis resonance structures. These results will shed further light on the design and electronic modulation of new carborane-based materials.

[Applicability of the Moyers mixed dentition analysis for the Hungarian population]. / A Moyers-féle vegyes fogazati analízis alkalmazhatóságának vizsgálata a magyarországi lakosság körében.

Introduction: Moyers mixed dentition analysis is one of the most commonly used prediction methods to estimate the size of the unerupted teeth. By its use, we can determine the severity of tooth size-arch length discrepancies in mixed dentition. Since the tooth size may vary considerably among different ethnic groups, for the most precise estimation of the required space, an analysis based on the individual's own ethnic group would be recommended. Aim: Our aim was to evaluate the applicability of Moyers mixed dentition analysis for the Hungarian population. Method: Upper and lower study casts of 370 patients were evaluated. The mesiodistal widths of the teeth were measured by using a Pittsburgh digital caliper. The odontometric values obtained were used to calculate actual and predicted values. The actual teeth measurements were then statistically compared to the predicted values derived from Moyers probability tables. Results: Using Moyers analysis, we found significant differences at each percentile between the actual and predictive values in both sexes. In the upper jaw, values for men at the 95th, 85th, 75th, and 65th percentile overestimated the actual values, while for women only the 65th percentile underestimated it. In the lower jaw, all values were overestimated in relation to the actual measurements at all percentiles. Conclusions: Based on our results, Moyers mixed dentition analysis cannot be reliably applied for the Hungarian population. If used, it is recommended to use the Moyers predicted values at the 65th instead of the 75th percentile, as this will result in closer estimation to the actual space requirements. Orv Hetil. 2019; 160(50): 1984-1989.