Guided endodontics: accuracy of access cavity preparation and discrimination of angular and linear deviation on canal accessing ability—an ex vivo study

Background Guided endodontics technique has been introduced for years, but the accuracy in different types of teeth has yet to be assessed. The aim of this study is to evaluate the accuracy of three dimensional (3D)-printed endodontic guides for access cavity preparation in different types of teeth, and to evaluate the predictive ability of angular and linear deviation on canal accessibility ex vivo. Method Eighty-four extracted human teeth were mounted into six jaw models and categorised into three groups: anterior teeth (AT), premolar (P), and molar (M). Preoperative cone beam computed tomography (CBCT) and surface scans were taken and matched using implant planning software. Virtual access cavity planning was performed, and templates were produced using a 3D printer. After access cavities were performed, the canal accessibility was recorded. Postoperative CBCT scans were superimposed in software. Coronal and apical linear deviations and angular deviations were measured and evaluated with nonparametric statistics. The receiver operating characteristic (ROC) curve was used to evaluate the predictive ability of angular and linear deviation for canal accessibility in SPSS v20. Results A total of 117 guided access cavities were created and 23 of them were record as canal inaccessibility, but all canals were accessible after canal negotiation. The average linear deviation for all groups was 0.13 ± 0.21 mm at coronal position, 0.46 ± 0.4 mm at apical position, and 2.8 ± 2.6° in angular deviation. At the coronal position, the linear deviations of the AT and P groups were significantly lower than M group deviation (P < 0.05), but no statistically significant difference between AT group and P group. The same results were found in linear deviation at the apical position and in angular deviation. The area under the ROC curve was 0.975 in angular deviation, 0.562 in linear deviation at the coronal position, and 0.786 at the apical position. Statistical significance was noted in linear deviation at the apical position and in angular deviation (P < 0.001). Conclusions In conclusion, this study demonstrated that the accuracy of access cavity preparation with 3D-printed endodontic guides was acceptable. The linear and angular deviations in the M group were significantly higher than those in the other groups, which might be caused by the interference of the opposite teeth. Angular deviation best discriminated the canal access ability of guided access cavity preparation. Graphical Abstract

Morphology of the Cutaneous Poison and Mucous Glands in Amphibians with Particular Emphasis on Caecilians (Siphonops annulatus)

Caecilians (order Gymnophiona) are apodan, snake-like amphibians, usually with fossorial habits, constituting one of the most unknown groups of terrestrial vertebrates. As in orders Anura (frogs, tree frogs and toads) and Caudata (salamanders and newts), the caecilian skin is rich in mucous glands, responsible for body lubrication, and poison glands, producing varied toxins used in defence against predators and microorganisms. Whereas in anurans and caudatans skin gland morphology has been well studied, caecilian poison glands remain poorly elucidated. Here we characterised the skin gland morphology of the caecilian Siphonops annulatus, emphasising the poison glands in comparison to those of anurans and salamanders. We showed that S. annulatus glands are similar to those of salamanders, consisting of several syncytial compartments full of granules composed of protein material but showing some differentiated apical compartments containing mucus. An unusual structure resembling a mucous gland is frequently observed in lateral/apical position, apparently connected to the main duct. We conclude that the morphology of skin poison glands in caecilians is more similar to salamander glands when compared to anuran glands that show a much-simplified structure.

Sakhalinencyrtus leleji Simutnik gen. et sp. nov. of earliest Encyrtidae (Hymenoptera, Chalcidoidea) from Sakhalinian amber

Another earliest representative of the family Encyrtidae, Sakhalinencyrtus leleji Simutnik gen. et sp. nov., is described and illustrated based on a male specimen from the middle Eocene Sakhalinian amber. Similarly to other Encyrtidae from Sakhalinian amber, the new fossil fundamentally differs from encyrtids from late Eocene European ambers as well as from modern ones. Moreover, it probably belongs to a stem group of the family. The new genus is characterized by extremely apical position of cerci, long veins of the forewing with expanded parastigma, stigmal vein with long uncus, and absence of filum spinosum. The forewing venation of the new genus is very similar to that of Sugonjaevia Simutnik, 2015, but these genera differ by the structure of Mt8, hypopygium, genitalia, and clava.

Guided Endodontics: Accuracy of Access Cavity Preparation and Discrimination of Angular and Linear Deviation On Canal Accessing Ability – An Ex Vivo Study

Background Guided endodontics technique has been introduced for years, but the accuracy in different types of teeth has yet to be assessed. The aim of this study is to evaluate the accuracy of three dimensional (3D)-printed endodontic guides for access cavity preparation in different types of teeth, and to evaluate the predictive ability of angular and linear deviation on canal accessibility ex vivo. Method Eighty-four extracted human teeth were mounted into six jaw models and categorised into three groups: anterior teeth (AT), premolar (P), and molar (M). Preoperative cone beam computed tomography (CBCT) and surface scans were taken and matched using implant planning software. Virtual access cavity planning was performed, and templates were produced using a 3D printer. After access cavities were performed, the canal accessibility was recorded. Postoperative CBCT scans were superimposed in software. Coronal and apical linear deviations and angular deviations were measured and evaluated with nonparametric statistics. The receiver operating characteristic (ROC) curve was used to evaluate the predictive ability of angular and linear deviation for canal accessibility in SPSS v20. Results A total of 117 guided access cavities were created and 23 of them were record as canal inaccessibility, but all canals were accessible after canal negotiation. The average linear deviation for all groups was 0.13 ± 0.21 mm at coronal position, 0.46 ± 0.4 mm at apical position, and 2.8 ± 2.6° in angular deviation. At the coronal position, the linear deviations of the AT and P groups were significantly lower than M group deviation (P < 0.05), but no statistically significant difference between AT group and P group. The same results were found in linear deviation at the apical position and in angular deviation. The area under the ROC curve was 0.975 in angular deviation, 0.562 in linear deviation at the coronal position, and 0.786 at the apical position. Statistical significance was noted in linear deviation at the apical position and in angular deviation (P < 0.001). Conclusions In conclusion, this study demonstrated that the accuracy of access cavity preparation with 3D-printed endodontic guides was acceptable. The linear and angular deviations in the M group were significantly higher than those in the other groups, which might be caused by the interference of the opposite teeth. Angular deviation best discriminated the canal access ability of guided access cavity preparation.

The first oxazoline adduct of Zn(acac)2: bis(acetylacetonato-j2O,O0)(2-phenyl-2- oxazoline-jN)zinc(II)

The title material, [Zn(C(5)H(7)O(2))(2)(C(9)H(9)NO)], was synthesized by the treatment of bis-(acetyl-acetonato)zinc(II) monohydrate with 2-phenyl-2-oxazoline. The Zn atom is coordinated by two chelating acetyl-acetonate groups and one oxazoline ligand in the apical position of a slightly distorted square-pyramidal metal-ligand geometry.

The first oxazoline adduct of Zn(acac)2: bis(acetylacetonato-j2O,O0)(2-phenyl-2- oxazoline-jN)zinc(II)

The title material, [Zn(C(5)H(7)O(2))(2)(C(9)H(9)NO)], was synthesized by the treatment of bis-(acetyl-acetonato)zinc(II) monohydrate with 2-phenyl-2-oxazoline. The Zn atom is coordinated by two chelating acetyl-acetonate groups and one oxazoline ligand in the apical position of a slightly distorted square-pyramidal metal-ligand geometry.

Impact of homeometric autoregulation using a stepwise change in heart rate on dP/dtmax and time to peak dP/dt with resynchronization therapy

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Norwegian South East heath Authorities Background We investigated the homeometric autoregulation utilizing a stepwise change in heart rate on dP/dtmax and time to peak dP/dt (Td) with biventricular pacing (BIVP) and the LV lead positioned in the apical, anterior and lateral positions. Pacing at low HR (LHR) and high heart rates (HHR) changes contractility through homeometric autoregulation (Bowditch effect) without changing the resynchronization itself. Purpose To determine the effect of a change in contractility through homeometric autoregulation on two different effect measures of resynchronization therapy. Methods Twenty-nine patients in heart failure with LBBB underwent CRT implantation with continuous LV pressure registration. The LV lead was first placed in either apical or anterior position followed by a permanent placement in a lateral position. Sequential BIVP pacing was performed for one minute, at a rate 10% above intrinsic heart rate (LHR = 75 ± 9bpm), before dP/dtmax measurements were recorded, and the sequence was repeated with pacing rate increased by 30% (HHR = 98 ± 11bpm). Td was defined as the time from pacemaker stimuli to peak dP/dt. Mixed linear models were used for statistics, numbers are estimated marginal means ± SEM. Significance was set at p &lt; 0.05. Results DP/dtmax was higher with HHR in lateral position (1036 ± 41mmHg/s) than with LHR (933mmHg/s). The same was observed for all other lead positions. However, there was no difference between lateral position with LHR and apical position with HHR (930 ± 44mmHg/s). There were no differences in Td between LHR and HHR, but Td was shorter with BIVP in lateral position at pacing LHR (158 ± 4ms) and HHR (155 ± 4ms) than in all other positions. Overall dP/dtmax increased by 10% from LHR to HHR (888 ± 41mmHg/s vs. 980 ± 41 mmHg/s), while overall Td decreased by 2.4% from 168 ± 4ms to 164 ± 4ms. We found a linear relationship between Td and dP/dtmax (R = 0.7) with β=-0.07 that would indicate a 6ms reduction in Td going from LHR to HHR. The overall change in Td from LHR to HHR could therefore be attributed to the change in dP/dtmax. Conclusion Homeometric regulation does not influence Td, but Td is sensitive to changes in resynchronization and pacing lead position. Td is shorter with BIVP in lateral position at both high and low HR as would be expected from a biomarker of resynchronization. HR influences dP/dtmax so distinction between optimal and non-optimal positions using dP/dtmax may be difficult without knowledge of homeometric state.

Aqua(1,4,7,10-tetraazacyclododecane)zinc(II) bis(perchlorate)

The cationic ZnII part of aqua(1,4,7,10-tetraazacyclododecane)zinc(II) bis(perchlorate), [Zn(C8H20N4)(H2O)](ClO4)2, exhibits a slightly distorted square-pyramidal coordination environment with a water molecule in the apical position. In the crystal, the macrocyclic ring alternates between two conformations with equal occupancies. Two of the three perchlorate anions are situated about a twofold rotation axis, and one of them shows disorder of the O atoms with occupancies of 0.62 (7) and 0.38 (7). In the crystal, the complexes are connected by intermolecular hydrogen bonding via the perchlorate anions.

Isoreticular Crystallization of Highly Porous Cubic Covalent Organic Cage Compounds

<p>Modular frameworks featuring well-defined pore structures in microscale domains establish tailor-made porous materials. For open molecular solids however, maintaining long-range order after desolvation is inherently challenging, since packing is usually governed by only a few supramolecular interactions. Here we report on two series of nanocubes obtained by co-condensation of two different hexahydroxy tribenzotriquinacenes (TBTQs) and benzene-1,4-diboronic acids (BDBAs) with varying linear alkyl chains in 2,5-position. ⁿButyl groups at the apical position of the TBTQ vertices yielded soluble model compounds, which were analyzed by mass spectrometry and NMR spectroscopy. In contrast, methyl-substituted cages spontaneously crystallized as isostructural and highly porous solids with BET surface areas and pore volumes of up to 3426 m² g⁻¹ and 1.82 cm³ g⁻¹. Single crystal X-ray diffraction and sorption measurements revealed an intricate cubic arrangement of alternating micro- and mesopores in the range of 0.97–2.2 nm that are fine-tuned by the alkyl substituents at the BDBA linker.</p>