Application of reference point indentation for micro-mechanical surface characterization of calcium silicate based dental materials

Effect of different root canal irrigants on surface roughness and microhardness of Biodentine combined with triple antibiotic paste: An in vitro study

Background

Biodentine is widely used for endodontic applications; recently, it has been incorporated with triple antibiotic paste (TAP). The effect of endodontic irrigants on the physical characteristics of this new combination needs to be studied.

Aims

The aim of the study was to evaluate the surface roughness and microhardness of Biodentine incorporated with TAP subjected to various endodontic irrigants.

Materials and Methods

Hundred cylindrical discs (6 mm × 3 mm) were prepared by mixing the Biodentine with TAP (3:1). The specimens were subjected to different irrigating solutions for 5 min in 5 groups (n = 20): Group 1: distilled water (control), Group 2: 2.5% sodium hypochlorite, Group 3: 17% ethylenediaminetetraacetic acid, Group 4: 2% chlorhexidine (CHX), and Group 5: 2% chitosan nanoparticles (CSNs). Half of the specimens in each group were subjected to surface roughness (n = 10) and another half to microhardness (n = 10). Surface roughness was measured using a surface roughness tester, and digital Vickers microhardness testing was performed on each specimen.

Statistical Analysis

One-way ANOVA and post hoc Tukey's tests (P ≤ 0.05) were used.

Results

The highest microhardness was found with 2% CSN, whereas 2% CSN and 2% CHX had a minimal effect on the surface roughness of Biodentine incorporated with TAP (P ≤ 0.05).

Conclusion

The root canal irrigant 2% CSN exhibited the highest microhardness and least surface roughness of modified Biodentine with TAP.

Breaking new ground in mineralized tissue: Assessing tissue quality in clinical and laboratory studies

Mineralized tissues, such as bone and teeth, have extraordinary mechanical properties of both strength and toughness. This mechanical behavior originates from deformation and fracture resistance mechanisms in their multi-scale structure. The term quality describes the matrix composition, multi-scale structure, remodeling dynamics, water content, and micro-damage accumulation in the tissue. Aging and disease result in changes in the tissue quality that may reduce strength and toughness and lead to elevated fracture risk. Therefore, the capability to measure the quality of mineralized tissues provides critical information on disease progression and mechanical integrity. Here, we provide an overview of clinical and laboratory-based techniques to assess the quality of mineralized tissues in health and disease. Current techniques used in clinical settings include radiography-based (radiographs, dual energy x-ray absorptiometry, EOS) and x-ray tomography-based methods (high resolution peripheral quantitative computed tomography, cone beam computed tomography). In the laboratory, tissue quality can be investigated in ex vivo samples with x-ray imaging (micro and nano-computed tomography, x-ray microscopy), electron microscopy (scanning/transmission electron imaging (SEM/STEM), backscattered scanning electron microscopy, Focused Ion Beam-SEM), light microscopy, spectroscopy (Raman spectroscopy and Fourier transform infrared spectroscopy) and assessment of mechanical behavior (mechanical testing, fracture mechanics and reference point indentation). It is important for clinicians and basic science researchers to be aware of the techniques available in different types of research. While x-ray imaging techniques translated to the clinic have provided exceptional advancements in patient care, the future challenge will be to incorporate high-resolution laboratory-based bone quality measurements into clinical settings to broaden the depth of information available to clinicians during diagnostics, treatment and management of mineralized tissue pathologies.

Reactivation potency of two novel oximes (K456 and K733) against paraoxon-inhibited acetyl and butyrylcholinesterase: In silico and in vitro models

Organophosphates (OPs) irreversibly inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. The reactivation of these inhibited enzymes is paramount for their normal function. Present study evaluates reactivation potency of two newly developed oximes, K456 and K733, against paraoxon (POX)-inhibited human-RBC-AChE and human-plasma-BChE in comparison to reported reactivator, pralidoxime (2-PAM). In vitro studies showed higher intrinsic toxicities of both oximes than 2-PAM for AChE. No substantial reactivation of hBChE was noted by tested concentration. Contrary to 2-PAM, the in silico study predicted lower binding free energies for both oximes. However, the detailed interaction study revealed inability of oximes to interact with catalytic anionic site of AChE and hBChE in contrast to 2-PAM. Both in vitro and in silico studies conclude that K456 and K733 are unlikely to be used as reactivators of paraoxon-inhibited AChE or BChE.