Evaluation of Compressive and Flexural Strengths of Two Resin-based Core Materials with an Alkasite Material: An In Vitro Study.

AIM: To compare and evaluate the compressive and flexural strengths of two resin-based core build-up materials with an alkasite material. MATERIALS AND METHODS: ParaCore, Tetric N ceram Bulk-fill composite, and Cention N were used. A total of 90 specimens were prepared. Customized cylindrical split molds of dimension 6 ± 1 mm (height) × 4 ± 1 mm (diameter) were used to fabricate 15 samples of each core material for testing the compressive strength and rectangular split metal molds of dimensions 25 ± 1 mm (length) × 2 ± 1 mm (width) × 2 ± 1 mm (height) were used to fabricate 15 samples of each core material for testing the flexural strength. Then the samples were tested using a Universal testing machine (UTM). RESULTS: The compressive and flexural strengths of Cention N were significantly less than ParaCore® but higher than Tetric® N-CeramTM Bulk-fill core build-up material. CONCLUSION: Within the limitations of this study, it was concluded that Cention N may be used as an alternative to other core build-up materials after further in-vitro and in-vivo studies. CLINICAL SIGNIFICANCE: Cention N had the added advantage that self-cure polymerization alone was sufficient to achieve good physical properties when compared to the other two resin-based core build-up materials.

Elusive Toxin in Cleistanthus collinus Causing Vasoconstriction and Myocardial Depression: Detailed NMR Analyses and Biological Studies of Cleistanthoside A.

Cleistanthus collinus leaf extracts are consumed for suicidal purposes in southern India. The boiled decoction is known to be more toxic than the fresh leaf juice. Although several compounds have been isolated and their toxicity tested, controversy remains as to which compounds are responsible for the high level of toxicity of C. collinus. We report herein that cleistanthoside A is the major toxin in the boiled aqueous extract of fresh leaves and causes death in rats in small doses. The toxicity of the boiled extract prepared in the manner described can be attributed entirely to cleistanthoside A. Cleistanthin A could also be isolated from the boiled extract, albeit in trace amounts. As hypotension not responding to vasoconstrictors is the cause of death in patients who have consumed the boiled extract, effects of cleistanthoside A on the determinants of blood pressure, namely, force of cardiac contraction and vascular resistance, were tested in isolated organ experiments. Cleistanthoside A has a direct vasoconstrictor effect; however, it inhibits ventricular contractility. Therefore, the notion that the shock in C. collinus poisoning is of vascular origin must be considered carefully, and the possibility of cardiogenic shock must be studied. We present the crystal structure of cleistanthin A and show the potency of fast NMR methods (NOAH4-BSCN-NUS) in the full spectral assignment of cleistanthoside A as a real-world sample of a natural product. We also compare the results of the NOAH4-BSCN-NUS NMR experiments with conventional NMR methods.