Synthesis and characterization of an experimental primer containing chitosan nanoparticles - Effect on the inactivation of metalloproteinases, antimicrobial activity and adhesive strength.

OBJECTIVE: The aim of this study was to synthesize and characterize an experimental primer containing cationic lipid nanoparticles (NPL-chitosan) and to evaluate its properties. DESIGN: The NPL-chitosan were synthesized by emulsion and sonication method. The experimental primers were applied in dentin surface of fifty human molars. The experimental groups were: 1) application of commercial primer; 2) Primer containing 2% of Chlorhexidine (CHX) 3); Primer with 2% NPL-chitosan 4); Primer with 0.6 % of NPL-chitosan 5); Primer with 0.4 % of NPL-chitosan. A composite resin plateau was used for the analysis, where sections were made for making the dentin beams. The effect of experimental primer with cationic nanoparticles in the inhibition of matrix metalloproteinase (MMP) activity was carrying out by in situ zymography. For the Resin-Dentin Adhesive Strength and in situ Zymography analysis, was used the One-way analysis of variance (ANOVA) with significance level of 95 %. RESULTS: Spherical NPL-chitosan presented size below 220 nm, polydispersity index of 0.179 and zeta potential positive and was stable over 75 days. These nanoparticles showed antibacterial activity agsainst S. mutans with MIC of the 0.4 % and MBC of 0.67 %. In the Microtensile Strength, no statistical difference was observed between the experimental groups (p = 0.9054). The in situ zymography assay showed that the group with 2% of NPL-chitosan presented higher inactivation activity of MMPs compared to the other groups (p < 0.05). CONCLUSION: The experimental primer containing NPL-chitosan has antimicrobial activity, does not alter the adhesive resistance and inactivates MMPs present in dentin.

Effect of image resolution manipulation in rearfoot angle measurements obtained with photogrammetry

The aim of this study was to investigate the influence of image resolution manipulation on the photogrammetric measurement of the rearfoot static angle. The study design was that of a reliability study. We evaluated 19 healthy young adults (11 females and 8 males). The photographs were taken at 1536 pixels in the greatest dimension, resized into four different resolutions (1200, 768, 600, 384 pixels) and analyzed by three equally trained examiners on a 96-pixels per inch (ppi) screen. An experienced physiotherapist marked the anatomic landmarks of rearfoot static angles on two occasions within a 1-week interval. Three different examiners had marked angles on digital pictures. The systematic error and the smallest detectable difference were calculated from the angle values between the image resolutions and times of evaluation. Different resolutions were compared by analysis of variance. Inter- and intra-examiner reliability was calculated by intra-class correlation coefficients (ICC). The rearfoot static angles obtained by the examiners in each resolution were not different (P > 0.05); however, the higher the image resolution the better the inter-examiner reliability. The intra-examiner reliability (within a 1-week interval) was considered to be unacceptable for all image resolutions (ICC range: 0.08-0.52). The whole body image of an adult with a minimum size of 768 pixels analyzed on a 96-ppi screen can provide very good inter-examiner reliability for photogrammetric measurements of rearfoot static angles (ICC range: 0.85-0.92), although the intra-examiner reliability within each resolution was not acceptable. Therefore, this method is not a proper tool for follow-up evaluations of patients within a therapeutic protocol.

Effect of image resolution manipulation in rearfoot angle measurements obtained with photogrammetry.

The aim of this study was to investigate the influence of image resolution manipulation on the photogrammetric measurement of the rearfoot static angle. The study design was that of a reliability study. We evaluated 19 healthy young adults (11 females and 8 males). The photographs were taken at 1536 pixels in the greatest dimension, resized into four different resolutions (1200, 768, 600, 384 pixels) and analyzed by three equally trained examiners on a 96-pixels per inch (ppi) screen. An experienced physiotherapist marked the anatomic landmarks of rearfoot static angles on two occasions within a 1-week interval. Three different examiners had marked angles on digital pictures. The systematic error and the smallest detectable difference were calculated from the angle values between the image resolutions and times of evaluation. Different resolutions were compared by analysis of variance. Inter- and intra-examiner reliability was calculated by intra-class correlation coefficients (ICC). The rearfoot static angles obtained by the examiners in each resolution were not different (P > 0.05); however, the higher the image resolution the better the inter-examiner reliability. The intra-examiner reliability (within a 1-week interval) was considered to be unacceptable for all image resolutions (ICC range: 0.08-0.52). The whole body image of an adult with a minimum size of 768 pixels analyzed on a 96-ppi screen can provide very good inter-examiner reliability for photogrammetric measurements of rearfoot static angles (ICC range: 0.85-0.92), although the intra-examiner reliability within each resolution was not acceptable. Therefore, this method is not a proper tool for follow-up evaluations of patients within a therapeutic protocol.