Abstract
Objective Tissue conditioners are composed of poly(ethyl methacrylate) (PEMA) powder and plasticizer/ethanol
mix liquid. Butyl phthalyl butyl glycolate (BPBG) plasticizer is commonly used in
tissue conditioners, but the main concern with phthalate plasticizer is its leachability
and biocompatibility, especially the estrogenic activity and cytotoxicity of phthalate.
Therefore, acetyl tributyl citrate (ATBC) plasticizer has been introduced and formulated
as plasticizer in tissue conditioner; however its leachability characteristics are
still unknown. Furthermore, the effect of foodsimulating liquids toward leachability
of BPBG and ATBC plasticizers has not been documented. The objective of this study
was to compare the effect of food-simulating liquids on the leachability of plasticizers
and hardness of two experimental tissue conditioners containing BPBG and ATBC plasticizers.
Materials and Methods Ten experimental materials were prepared using PEMA polymer powder with 95% plasticizer
(BPBG and ATBC) and 5% ethanol by volume, using powder to liquid ratio of 1.67:1,
and the thickness was controlled at 3 mm. Shore A hardness value was measured after
immersion in distilled water, artificial saliva, 25% ethanol/water mix, 3% citric
acid, and coconut oil at 37°C. Measurements were taken at 2 hours and 1, 2, 3, 4,
7, 10, 14, 21, 28, 42, 56, and 84 days. Six readings were taken for each sample and
hardness change was calculated and statistically analyzed using Wilcoxon signed-rank
test.
Results Increase in hardness value was noted for both plasticizers over time with the highest
increase was when immersed in coconut oil. Shore A hardness value was significantly
higher in ATBC after 84 days of immersion in all food-simulating liquids. The increase
in hardness is due to plasticizer/ethanol leaching; however, as ethanol content was
the same (5%), the hardness change is attributed to the leaching of plasticizers.
Conclusion Leaching of both plasticizers was highest in coconut oil indicating that tissue conditioners
may have a shorter intraoral lifetime in patients eating high-fat diet.
Keywords
tissue conditioner - plasticizer leaching - food-simulating liquids - Shore A hardness
