Impregnation with antimicrobials challenge bonding properties and water sorption behaviour of an acrylic liner

Impregnation with antimicrobials has an impact on degree of conversion and colour stability of acrylic liner

“…The colour changes could be attributed to differences in water sorption, chemical composition and residual monomer 23) . Interestingly, significant correlations between the DC and the colour change measured in this study and water uptake results reported previously 28) was detected for all drugs 28) . Accordingly, the poor colour stability of FLUc impregnated discs compared to all other groups is related to the higher water absorption and the higher amount of residual monomer as a result of incorporating a higher proportion of the FLUc powder in order to incorporate an equivalent amount of active drug into the discs.…”

“…A strong negative correlation between the degree of conversion and colour stability was demonstrated (r=0.97). In addition, a significant negative correlation between DC measured in this study and water absorption reported previously was detected (r=0.99, p=0.009) and a significant positive correlation between ΔE*ab measured in this study and water absorption reported previously was (r=0.97, p=0.027) 28) .…”

“…Accordingly, the poor colour stability of FLUc impregnated discs compared to all other groups is related to the higher water absorption and the higher amount of residual monomer as a result of incorporating a higher proportion of the FLUc powder in order to incorporate an equivalent amount of active drug into the discs. The control group showed the least colour change where the residual monomer and water absorption is lower 28) compared to other tested groups. This finding is reflected by the strong negative correlation between the colour change and the degree of conversion.…”

“…Linear regression was used to test the correlation between the degree of conversion and colour stability. Linear regression was used also to test the correlations between DC and ΔE*ab measured in this study with water uptake reported previously 28) .…”

“…This could be due to the increase in viscosity as polymerisation progresses which could lead to limited mobility of the functional groups of the monomer within the polymerising structure and eventually terminating the reaction before complete conversion 11) . All investigated groups apart from the FLUc impregnated group fulfilled the ISO specification 20795-1 criteria, where the residual monomer content should not exceed 4.5% 28,29) . However, our study tested the whole residual monomer content within the acrylic matrix which would be higher than the leached residual monomer especially in short term use as intended for the investigated acrylic resin 30,31) .…”