Effect of irradiance from curing units on the microhardness of composite - a systematic review.

Purpose The systematic review aims to evaluate the effect of light irradiance from light-curing units on microhardness of composite.Materials and methods The protocol was registered in PROSPERO following which primary search was carried out via MedLine, Scopus and Cochrane Library. A customised tool was used to assess the risk of bias.

Drug Repurposing for Tooth Regeneration: The Promising Premises.

Drug repurposing which identifies new therapeutic use(s) for drugs currently in use is a brand-new avenue of research interest worldwide. It circumvents the high-end monetary and time investment usually associated with contemporary drug discoveries. In the field of dentistry, recent studies in drug repurposing focuses in attaining dentin repair or reduction of bone resorption associated with apical periodontitis.

Variations in root canal morphology of permanent incisors and canines among Asian population: A systematic review and meta-analysis.

Objectives: This systematic review was designed to measure the pooled prevalence of morphological variations in the root canal of permanent incisors and canines among Asian adults.

Methods: An electronic search was conducted in the PubMed, Scopus, and EBSCO databases, and relevant studies were included. Studies reporting on the Vertucci canal configuration (types I to VIII) were included.

Detection of nucleic acids and other low abundance components in native bone and osteosarcoma extracellular matrix by isotope enrichment and DNP-enhanced NMR.

Sensitivity enhancement by isotope enrichment and DNP NMR enables detection of minor but biologically relevant species in native intact bone, including nucleic acids, choline from phospholipid headgroups, and histidinyl and hydroxylysyl groups. Labelled matrix from the aggressive osteosarcoma K7M2 cell line confirms the assignments of nucleic acid signals arising from purine, pyrimidine, ribose, and deoxyribose species. Detection of these species is an important and necessary step in elucidating the atomic level structural basis of their functions in intact tissue.

Poly(ADP-Ribose) Links the DNA Damage Response and Biomineralization.

Biomineralization of the extracellular matrix is an essential, regulated process. Inappropriate mineralization of bone and the vasculature has devastating effects on patient health, yet an integrated understanding of the chemical and cell biological processes that lead to mineral nucleation remains elusive. Here, we report that biomineralization of bone and the vasculature is associated with extracellular poly(ADP-ribose) synthesized by poly(ADP-ribose) polymerases in response to oxidative and/or DNA damage.

Essential but sparse collagen hydroxylysyl post-translational modifications detected by DNP NMR.

The sparse but functionally essential post-translational collagen modification 5-hydroxylysine can undergo further transformations, including crosslinking, O-glycosylation, and glycation. Dynamic nuclear polarization (DNP) and stable isotope enriched lysine incorporation provide sufficient solid-state NMR sensitivity to identify these adducts directly in skin and vascular smooth muscle cell extracellular matrix (ECM), without extraction procedures, by comparison with chemical shifts of model compounds. Thus, DNP provides access to the elucidation of structural consequences of collagen modifications in intact tissue.

Proline provides site-specific flexibility for in vivo collagen.

Fibrillar collagens have mechanical and biological roles, providing tissues with both tensile strength and cell binding sites which allow molecular interactions with cell-surface receptors such as integrins. A key question is: how do collagens allow tissue flexibility whilst maintaining well-defined ligand binding sites? Here we show that proline residues in collagen glycine-proline-hydroxyproline (Gly-Pro-Hyp) triplets provide local conformational flexibility, which in turn confers well-defined, low energy molecular compression-extension and bending, by employing two-dimensional C-C correlation NMR spectroscopy on C-labelled intact ex vivo bone and in vitro osteoblast extracellular matrix. We also find that the positions of Gly-Pro-Hyp triplets are highly conserved between animal species, and are spatially clustered in the currently-accepted model of molecular ordering in collagen type I fibrils.

Management of Cervically Fractured Central Incisors: A Multidisciplinary Approach.

Introduction: Fracture of tooth structure at or below the gingival margin compromises rehabilitation and hampers esthetics and function.

Management: Management of such cases by a post-core and crown restoration, or periodontal surgery or orthodontic extrusion alone may not always suffice in attaining a good result.

Case Report: A multi-disciplinary approach which includes all of the above mentioned procedures helps in long term success.

Solid state NMR of isotope labelled murine fur: a powerful tool to study atomic level keratin structure and treatment effects.

We have prepared mouse fur extensively C,N-labelled in all amino acid types enabling application of 2D solid state NMR techniques which establish covalent and spatial proximities within, and in favorable cases between, residues. C double quantum-single quantum correlation and proton driven spin diffusion techniques are particularly useful for resolving certain amino acid types. Unlike 1D experiments on isotopically normal material, the 2D methods allow the chemical shifts of entire spin systems of numerous residue types to be determined, particularly those with one or more distinctively shifted atoms such as Gly, Ser, Thr, Tyr, Phe, Val, Leu, Ile and Pro.

Preparation of highly and generally enriched mammalian tissues for solid state NMR.

An appreciable level of isotope labelling is essential for future NMR structure elucidation of mammalian biomaterials, which are either poorly expressed, or unexpressable, using micro-organisms. We present a detailed protocol for high level (13)C enrichment even in slow turnover murine biomaterials (fur keratin), using a customized diet supplemented with commercial labelled algal hydrolysate and formulated as a gel to minimize wastage, which female mice consumed during pregnancy and lactation. This procedure produced approximately eightfold higher fur keratin labelling in pups, exposed in utero and throughout life to label, than in adults exposed for the same period, showing both the effectiveness, and necessity, of this approach.

Reattachment of fractured tooth fragment with fiber post: a case series with 1-year followup.

Coronal fractures of the anterior teeth are common sequelae of dental trauma. In case of complex fractures, where the fractured segment is available and there is close approximation of the segment to the remaining tooth, root canal treatment followed by reattachment of the fractured segment with fiber post reinforcement is a feasible option. The procedure is simple and economic and needs less chair-side time as compared to many conventional methods.

Collagen labelling with an azide-proline chemical reporter in live cells.

We have developed a strategy for selective imaging of collagen in live foetal ovine osteoblasts. Our approach involves the incorporation of an azide-tagged proline in the biosynthesis of collagen followed by labelling using a strain-promoted [3+2] azide-alkyne cycloaddition reaction.

NMR spectroscopy of native and in vitro tissues implicates polyADP ribose in biomineralization.

Nuclear magnetic resonance (NMR) spectroscopy is useful to determine molecular structure in tissues grown in vitro only if their fidelity, relative to native tissue, can be established. Here, we use multidimensional NMR spectra of animal and in vitro model tissues as fingerprints of their respective molecular structures, allowing us to compare the intact tissues at atomic length scales. To obtain spectra from animal tissues, we developed a heavy mouse enriched by about 20% in the NMR-active isotopes carbon-13 and nitrogen-15.