DIMENSIONAL STABILITY OF LIGNIN INCORPORATED ALGINATE IMPRESSION MATERIAL ---AN IN VITRO PILOT STUDY
The aim of this pilot study was to determine and compare the dimensional stability of alginate impression material impregnated in different concentrations (0.75%, 1.5% and 3%) of lignin alkali with unmodified alginate at a storage time of 0-hour, 1 hour and 24 hours. Unmodified alginate impression material served as control group. Experimental groups A,B and C contained alginate impression material modified with Lignin alkali powder in 0.75% w/w, 1.5% w/w & 3% w/w respectively. To determine the dimensional stability a stainless-steel ruled test block was fabricated, which consisted of three parts Ruled block (A-A), Mould (B-B) and a Riser (C-C). The mixed material was placed immediately onto the mould by means of a stainless-steel spatula. The filled mould was covered with a thin sheet of polyethylene followed by a glass slab (weighing 75± 5 grams). After setting the mould was separated from the test block and the specimen was pressed out of the mould with the help of the riser (C-C). Storage of all the specimens for 1 hour and 24 hours was done in an incubator at 25oC ± 1. Digital images of the all-selected specimens were taken at 0-hour, at 1-hour interval and 24 hours interval with the help of a Canon scanner. Middle horizontal line in each impression’s scanned image was measured using the tools of a software program (Adobe reader). Data was analyzed using software SPSS version 20. The mean difference of dimensional stability between groups at each stage were analyzed by one way ANOVA, followed by Post hoc Tukey test for comparison within groups. Level of significance was set at p<0.05. A statistically significant difference was found between the dimensional stability values of experimental groups A, B, C and control group at 1 hour (p<0.001) and 24 hours (p<0.000). No significant difference was found between the dimensional stability values of experimental group A, B, C and control group at 0 hour (p<0.310). The use of lignin alkali to improve the dimensional stability in alginate impression holds capability and further clinical research is needed in this direction.
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