The prevalence, predictive factors, and classification of intrapulpal cracks in maxillary premolars requiring endodontic treatment

Cracked teeth may be difficult to diagnose. Craze lines rarely become symptomatic or require treatment. Cracks in the enamel and dentin alone may or may not become symptomatic and require restorative treatment. However, cracks extending into the enamel, dentin, and pulp chamber provide an avenue for bacteria to establish infection and this commonly results in symptoms and the need for endodontic and restorative treatment. The published endodontic literature has limited information regarding the prevalence or predictive factors for cracks extending into the pulp chamber of teeth. The purpose of this study was to determine the prevalence and classification of intrapulpal cracks in maxillary premolars and to identify factors that may aid in diagnosing the existence and extent of a crack. The cracks were classified according to the Intrapulpal Crack Classification System proposed by Detar in 2014. All maxillary premolar teeth treatment planned for non-surgical root canal therapy (NSRCT) or retreatment (RETX) at Virginia Commonwealth University (VCU) Graduate Endodontic Practice from January 2014 through February 2015 were included in the study after obtaining patient consent. Teeth were examined visually, stained, and examined microscopically for the presence of an intrapulpal crack. Demographic information, subjective data associated with the chief complaint, objective results of diagnostic testing (percussion, palpation, bite stick test, transillumination, probing depths), existing restorations, pulpal diagnosis, and periapical diagnosis were analyzed using chi-square and multiple logistic regression (

Analysis of the H-bridge in Carboxyllic Acids in Terms of Stabilization Energy Derived from Bond Lengths. Non-Hammett Properties of p-Substituted Benzoic Acids in the Crystalline State

Harmonic oscillator stabilization energy (HOSE) is defined as the negative value of deformation energy necessary to transform a molecule from its natural geometry to its Kekule structure with purely single and double bonds. It was found that HOSE-values for dimers of carboxylic acids with centrosymmetric hydrogen bonds are well related (correlation coeff. r = 0.972) to the Ro . . . o distances for 19 species for which measurements were carried out in both the crystalline and gaseous states. Stability of many other Jt- systems, e. g. aromatic and unsaturated hydrocarbons, polymethine systems (e.g. cyanine dyes), EDA-complexes, quinoid systems, etc. are successfully described in terms of HOSE-values

Why 1,2‑quinone derivatives are more stable than their 2,3‑analogues?

In this work, we have studied the relative stability of 1,2- and 2,3-quinones. While 1,2-quinones have a closed-shell singlet ground state, the ground state for the studied 2,3-isomers is open-shell singlet, except for 2,3-naphthaquinone that has a closed-shell singlet ground state. In all cases, 1,2-quinones are more stable than their 2,3-counterparts. We analyzed the reasons for the higher stability of the 1,2-isomers through energy decomposition analysis in the framework of Kohn–Sham molecular orbital theory. The results showed that we have to trace the origin of 1,2-quinones’ enhanced stability to the more efficient bonding in the π-electron system due to more favorable overlap between the SOMOπ of the ·C4n−2H2n–CH·· and ··CH–CO–CO· fragments in the 1,2-arrangement. Furthermore, whereas 1,2-quinones present a constant trend with their elongation for all analyzed properties (geometric, energetic, and electronic), 2,3-quinone derivatives present a substantial breaking in monotonicity.European Union in the framework of European Social Fund through the Warsaw University of Technology Development Programme. O.A. S., H. S. and T.M. K

Effect of the Orientational Disorder on the Observed Geometry of Carboxylic Group in Dimers of Carboxylic Acids in Crystalline State

Joint considerations of twofold symmetry axes producing various orientations of carboxylic groups and of non-coplanarity of these groups in a dimer lead to a new classification of orientational disorder in crystal s of cyclic dimers of carboxylic acids. Analysis of the geometry and particularly of the anisotropic thermal parameters of carboxylic atoms allows one to distinguish between the possible types of orientational disorder. Influences of dynamic disorder and mesomeric effects are discussed as well

(E)-N′-Benzyl­idene-p-toluene­sulfono­hydrazide

In the title compound, C14H14N2O2S, a novel sulfonamide derivative, an intra­molecular C—H⋯O hydrogen bond generates an S(5) ring motif. The mol­ecule adopts a twisted E configuration around the C=N bond. An inter­molecular N—H⋯O hydrogen bond generates an R 2 2(8) ring motif. The dihedral angle between the rings is 85.37 (9)°. The H atoms of the methyl group have rotational disorder with refined site occupancies of ca 0.63/0.37. In the crystal structure, inter­molecular N—H⋯O hydrogen bonds link neighbouring mol­ecules into dimers which stack along the a axis with a centroid–centroid distance of 3.8856 (10) Å

Infrared and Raman Studies of Carbonyl Group Frequencies of p-Substituted Benzoic Acids in the Crystalline State

Infrared and Raman carbonyl stretching frequencies for p - substituted benzoic acids in the crystalline state were measured and discussed in terms of the Hammett equation and hydrogen · bond strength

Metal Complexation and H-bonding Effects on Electronic Structure of Cytosine Studied in the Gas Phase

The influence of H-bonding and complexation with cations (probed by HF, F–, Li+, Na+ and K+) on structural and π-electron changes in the six most stable cytosine tautomers has been studied in the gas phase using the B3LYP/6-311++G(2d,2p) computational level. The presence of two exo- groups (ami-no/imino and carbonyl/hydroxyl) in cytosine tautomers significantly increases their sensitivity to structur¬al changes due to intra- and intermolecular interactions. These interactions induce large changes in aroma¬ticity of the rings and in the CX (X = N, O) bond lengths of exocyclic groups. Three types of H-bonds, considering their strength, could be distinguished: (i) charge-assisted X–•••HF, X = N or O, as the strong¬est, (ii) neutral X•••HF, where X is the nitrogen atom of the ring or imino group or the keto form oxygen atom and (iii) also neutral X•••HF, where X being either amino N or alternatively hydroxylic O. Hydrogen bond energy decreases approximately twice in the above listed sequence of interactions. Structural conse¬quences of H-bonding and metal complexation have been observed not only in the immediate region of the interaction but also in other parts of the molecule (the shape of the amino group, changes in CO and CN bond lengths). Complexation of the cytosine tautomers with cations leads to monotonic changes in aromaticity in line with an increase of their ionic radii

Ear-Specific Cochlear Implant Outcomes in Younger and Older Adults

Auditory information is transmitted from the ear to the brain along an intricate network of structures that comprise the central auditory nervous system. It is well documented that the neural pathway from the ear to the contralateral auditory cortex is stronger and more efficient than the pathway from the ear to the ipsilateral auditory cortex (Lazard et al., 2012; Lipschutz et al., 2002). In the majority of individuals, a functional specialization of the left cerebral hemisphere exists for language processing (Geschwind, 1972; Geschwind & Levitsky, 1968; Kimura, 1961; Jancke et al., 2002; Tervaniemi & Hugdahl, 2003). Due to this crossed nature of the central auditory system, the right ear has direct access to the language-dominant cerebral hemisphere, which results in superior right ear performance, or the Right Ear Advantage (REA), on dichotic listening tasks (Kimura, 1967). A body of literature reveals that the REA becomes more exaggerated with increased age (Martin & Cranford, 1991; Strouse et al., 2011; Roup et al., 2006; Jerger et al., 1995; Jerger & Johnson, 1992; Bellis & Wilber, 2001). The increase in the REA in older adults, in the presence of symmetrical hearing sensitivity, is thought to reflect age-related degradation of the corpus callosum, which compromises the transfer of auditory information between the cerebral hemispheres (Bellis & Wilber, 2001). Speech information presented to the left ear preferentially stimulates the right auditory cortex and must be transmitted by way of the corpus callosum in order to be processed in the language-rich left auditory cortex. Superior right-ear performance is therefore demonstrated in older adults, due to the primary projection of the right ear to the dominant hemisphere. The present study aimed to determine if ear-specific differences in speech understanding exist in younger and older adults who underwent unilateral cochlear implantation. Post-operative performance on speech outcome measures (Consonant-Nucleus-Consonant words and AZ-Bio Sentences) was compared between younger adults (18-69 years) and older adults (70+ years). Results revealed significant benefits in speech perception following implantation for both younger and older adults. Ear of implantation had no significant effect on post-operative speech outcomes in either group