Hyaluronic acid in Pluronic F-127/F-108 hydrogels for postoperative pain in arthroplasties: Influence on physico-chemical properties and structural requirements for sustained drug-release.

In this study, we reported the hyaluronic acid (HA) on supramolecular structure of Pluronic F-127 (PLF-127) and/or Pluronic F-108 (PLF-127) hydrogels, as well as their effects on release mechanisms, looking forward their application as lidocaine (LDC) drug-delivery systems in arthroplastic surgeries. We have studied the HA-micelle interaction using Dynamic Light Scattering (DLS), the micellization and sol-gel transition processes by Differential Scanning Calorimetry (DSC) and Rheology., of PL-based hydrogels and. The presence of HA provided the formation of larger micellar dimensions from ~26.0 to 42.4nm. The incorporation of HA did not change the micellization temperatures and stabilized hydrogels rheological properties (G'>G″), showing no interference on PL-thermoreversible properties. Small-Angle-X-ray Scattering (SAXS) patterns revealed that HA incorporation effects were pronounced for PLF-127 and PLF-108 systems, showing transitions from lamellar to hexagonal phase organization (HA-PLF-127) and structural changes from cubic to gyroid and/or cubic to lamellar. The HA insertion effects were also observed on drug release profiles, since lower LDC release constants (Krel=0.24-0.41mM·h-1) were observed for HA-PLF-127, that presented a hexagonal phase organization. Furthermore, the HA-PL systems presented reduced in vitro cytotoxic effects, pointed out their tendency to self-assembly and possible application as drug delivery systems.

Polycaprolactone fibers with self-assembled peptide micro/nanotubes: a practical route towards enhanced mechanical strength and drug delivery applications.

Peptide-based scaffolds are a frontier research area in materials science with widespread impact in biomedical engineering. In this paper, we describe a hybrid material formulated through the conjugation of electrospun polycaprolactone (PCL) fibers and micro/nanotubes of l,l-diphenylalanine (FF-MNTs). Morphology and crystallinity of the composite matrices are investigated using a wide range of analytical techniques including electron microscopy, thermal analyses, X-ray diffraction and micro-tomography. Peptide assemblies are found to produce deep modifications on the microstructure of PCL fibers, impacting average diameters, crystallinity degree and porous size in the polymer network. These changes are correlated with mechanical properties of the resulting scaffolds, whose strength is found to exhibit a brittle-to-ductile transition upon increasing the amount of FF-MNTs and lead to enhanced Young's moduli of polymer fibers. The PCL/FF-MNTs composites were tested for the drug delivery application of a lipophilic drug, benzocaine. In vitro permeation studies have shown that these polymer/peptide hybrids are able to produce a steady release of benzocaine over periods of up to ∼13 hours, much higher than commercially available gel formulations. Enzymatic tests have shown a significant increment in biodegradation rates in PCL/FF-MNTs hybrids containing higher peptide amounts, which exhibited almost 100% weight loss against only 10% found in pure PCL. Our findings indicate that using PCL/FF-MNTs materials is a simple route towards achieving enhanced mechanical strength of PCL networks that have the ability to promote controlled drug delivery from a completely biodegradable matrix.

Diagnosis of approximal caries in primary teeth: radiographic versus clinical examination using tooth separation.

PURPOSE: To compare the accuracy of clinical examination performed with bitewing radiographs or clinical examination using tooth separation to identify carious lesion activity. MATERIALS AND METHODS: 320 surfaces from 40 bitewing radiographs were examined for approximal caries on the maxillary and mandibular primary molars of 20 patients 3-10 years old. The patients were divided into three groups: (1) Absence of the permanent first molar; (2) Partial eruption of the permanent first molar; and (3) Full eruption of the permanent first molar. Two examiners evaluated the radiographs using a megascope, a magnifying glass (x2), and an amplifying image screen. Approximal radiolucencies were identified on 72 surfaces. Following the radiographic examinations, the two examiners performed conventional clinical inspection using a No. 4 dental mirror, a No. 5 dental explorer, and an air-water syringe, with artificial light and relative isolation. The separation method was performed with elastic bands, which were removed after 24 hours, and the clinical examination conducted as in the non-separation group. RESULTS: The correlation between the extension of interproximal radiolucent lesions in primary dentition and their clinical diagnoses following separation of the teeth, was similar to findings on literature evaluating the permanent dentition. On radiographic findings for enamel lesions, white spots predominated both in the inner (100%) and in the outer (94%) half of enamel upon clinical examination with separation of teeth. For radiolucent lesions in dentin, on the other hand, cavities predominated over white spot lesions (84%). In Groups 1 and 2 (young primary), white spots occurred in cases where the radiolucent lesions reached the dentin (15% and 25%), similar to findings for young permanent teeth. Clinical diagnosis performed with the mechanical separation of teeth cannot be considered conclusive for the primary dentition.