Publications by authors named "Luis Alberto Santos"

The aim of this study was to develop and to characterize a methacrylate-based root canal sealer containing chlorhexidine (CHX) and α-tricalcium phosphate (α-TCP). Experimental dual cure methacrylate-based sealer was produced containing 0, 2.5, or 5 wt% of CHX and 0, 25, or 50 wt% of α-TCP.

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Objective: Use of metal springs for treatment of craniosynostosis is gaining ground in the surgical armamentarium, as these springs simplify operative technique, help to avoid extended approaches, and thus minimize morbidity. Nevertheless, these devices have to be removed eventually. The purpose of this study was to perform cranial expansion with a fully integrated, biodegradable polymer spring in an animal model and to assess the efficacy of and histological reaction to this device.

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Purpose: To evaluate experimental cranial vault reconstructions, by combining bone morphogenetic protein type 2 (BMP-2) and different matrices.

Methods: Fourty-nine animals were initially included (seven per group). We designed an experimental, open, prospective and comparative study, divided in seven groups: 1 - BMP-2+calcium phosphate (BT); 2 - BMP-2+acellular dermal matrix (BM); 3 - BMP-2+calcium alginate (BA); 4 - TCP; 5 - MDM; 6 - ALG; 7 - Bone autograft (BAG).

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Biocompatibility, injectability and in situ self-setting are characteristics of calcium phosphate cements which make them promising materials for a wide range of clinical applications in traumatology and maxillo-facial surgery. One of the main disadvantages is their relatively low strength which restricts their use to nonload-bearing applications. α-Tricalcium phosphate (α-C3P) cement sets into calcium-deficient hydroxyapatite (CDHA), which is biocompatible and plays an essential role in the formation, growth and maintenance of tissue-biomaterial interface.

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Article Synopsis
  • β-dicalcium silicate (β-C₂ S) is a key component in Portland cement and acts as a hydraulic cement, providing strength through its reaction with water to form a hydrated phase.
  • The study synthesized β-C₂ S using a sol-gel process to create a new type of cement called CSiC, and evaluated its bioactivity and biocompatibility through tests in simulated body fluids and human cell cultures.
  • Results indicated that the sol-gel method effectively produced a pure β-C₂ S powder at low temperatures, forming a bone-like layer on its surface and exhibiting compressive strength similar to human bone, while also showing non-toxic effects on cell growth.
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Calcium phosphate cements used as bone substitutes generally have low mechanical strength compared with the bones of the human body. To solve these needs, we have incorporated hydrogels in the manufacture of samples made of alpha-tricalcium phosphate (α-TCP) cement, developing a system of dual-setting cement. This study aimed to produce composite materials by combining α-TCP powder and hydrogels.

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The use of calcium phosphate-based biomaterials has revolutionized current orthopedics and dentistry in repairing damaged parts of the skeletal system. Among those biomaterials, the cement made of hydraulic grip calcium phosphate has attracted great interest due to its biocompatibility and hardening "in situ". However, these cements have low mechanical strength compared with the bones of the human body.

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Silicon compounds are known as bioactive materials that are able to bond to the living bone tissue by inducing an osteogenic response through the stimulation and activation of osteoblasts. To improve the bioactive and mechanical properties of an α-Ca(3)PO(4)-based cement, the effects of the addition of Ca(3 SiO(5) (C(3)S) on physical, chemical, mechanical, and biological properties after soaking in simulated body fluid (SBF) were studied. The morphological and structural changes of the material during immersion were analyzed by X-ray diffraction and scanning electron microscopy.

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Purpose: To evaluate the ability of macroporous tricalcium phosphate cement (CPC) scaffolds to enable the adhesion, proliferation, and differentiation of mesenchymal stem cells derived from human bone marrow.

Methods: Cells from the iliac crest of an adult human donor were processed and cultured on macroporous CPC discs. Paraffin spheres sized between 100 and 250µm were used as porogens.

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Polylactic acid is a polymer of great technological interest, whose excellent mechanical properties, thermal plasticity, and bioresorbability render it potentially useful for environmental applications, as a biodegradable plastic and as a biocompatible material in biomedicine. This article discusses the synthesis and characterization of poly-L-lactic acid, obtained through two synthetic routes: direct polycondensation reactions without organic solvents, and in a supercritical medium. Tin complexes were used as catalysts in both polymerization reactions.

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alpha-Tricalcium phosphate bone cement, as formerly designed and developed by Driessens et al., consists of a powder composed by alpha-tricalcium phosphate (alpha-TCP) and hydroxyapatite (HA) seeds, and an aqueous solution of Na2HPO4 as mixing liquid. After mixing powder and liquid, alpha-TCP dissolves into the liquid and calcium deficient hydroxyapatite (CDHA), more insoluble than the former, precipitates as an entanglement of crystals, which causes the setting and hardening of the cement.

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Article Synopsis
  • - Calcium phosphate bone cements are great for orthopedic use due to their biocompatibility and bioactivity, making them effective for bone healing, but they struggle with low mechanical strength and toughness compared to human bone.
  • - This study focused on enhancing the mechanical properties of alpha-tricalcium phosphate-based cement by adding polypropylene, nylon, and carbon fibers, assessing how these additions affect the cement's performance.
  • - While adding fibers decreased the cement's compression strength due to increased porosity, it significantly improved its toughness and tensile strength, suggesting potential applications in areas that experience bending forces.
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