Deproteinization Effectiveness on Occlusal Enamel Surfaces and Resultant Acid Etching Patterns: An in vitro Study.

PURPOSE: The goal of this in vitro study was to identify whether occlusal enamel deproteinization is effective in the removal of organic material in order to obtain quality etching patterns using phosphoric acid (H3PO4) and sodium hypochlorite (NaOCl) compared to phosphoric acid alone. STUDY DESIGN: Nine extracted third permanent molars were polished with pumice and water. Every pit and fissure was evaluated as a unit, resulting in 40 individual units and then these were divided into five treatment groups. The occlusal enamel surface of each group was subjected to the following treatments: Group 1 (C) Control: No treatment; Group 2 (P): Polish and rinse; Group 3 (PD): Polish, rinse, and sodium hypochlorite (NaOCl) 5.25% for 60 seconds; Group 4 (PA): Polish, rinse, and acid etching with H3PO4 37% for 15 seconds; and Group 5 (PDA): Polish, rinse, sodium hypochlorite (NaOCl) 5.25% for 60 seconds, and acid etching with H3PO4 37% for 15 seconds. Results showed no significant statistical difference in the organic material present between groups 1 (C) (30.18%) and 2 (P) (36.61%), but there was a statistical difference (p <0.002) between Groups 1 and 2, and Group 3 (PD) (16.50%). In the acid etching group, the undesirable Type-III pattern (discussed later) was found in Group 4 (PA) (33.54%), while this was only 7.70% in Group 5, nearly five times more than Group 4, with a significant statistical difference (0.05). When differences were sought for Types I and II etch patterns (discussed later) for Groups 4 and 5, Group 4 (PA) obtained 26.29% (Type I) and 1.75% (Type II) etch patterns, compared to Group 5 (PDA) with 33.4% (Type I) and 38.97% (Type II) etch patterns. CONCLUSIONS: The enamel deproteinization technique is an effective way to remove organic material on the occlusal surfaces of teeth, obtaining after phosphoric acid application, up to 72.38% of Types I and II etch patterns. Etching Types I or II can also be determined by the removal of organic material in between enamel crystals.

Nanofibers of cellulose bagasse from Agave tequilana Weber var. azul by electrospinning: preparation and characterization.

In this study, cellulose of bagasse from Agave tequilana Weber var. azul was extracted to elaborate nanofibers by the electrospinning technique. Fiber characterization was performed using Transmission Electron Microscopy (TEM), x-ray, Fournier Transform-InfraRed (FT-IR) spectroscopy, and thermal analysis by Differential Scanning Calorimetry-Thermogravimetric Analysis (DSC-TGA). Different diameters (ranging from 54.57 ±â€¯0.02 to 171 ±â€¯0.01 nm) of nanofibers were obtained. Cellulose nanofibers were analyzed by means of x-ray diffraction, where we observed a total loss of crystallinity in comparison with the cellulose, while FT-IR spectroscopy revealed that the hemicellulose and lignin present in the agave bagasse were removed. Thermal analysis showed that nanofibers exhibit enhanced thermal properties, and the zeta potential value (-32.5 mV) demonstrated moderate stability in the sample. In conclusion, the nanofibers obtained provide other alternatives-of-use for this agro-industrial residue and could have potential in various industrial applications, among these encapsulation of bioactive compounds and reinforcing material, to mention a few.