Effect of aging on tear strength and cytotoxicity of soft denture lining materials; in vitro.
OBJECTIVE
The aim of this in vitro study was to evaluate the effect of aging on the tear strength and cytotoxicity of four soft denture lining materials.


METHODS
Four commonly used soft denture lining materials, (Coe-Comfort™ GC America Inc., Alsip, IL, USA; Coe-Soft™ GC America Inc., Alsip, IL, USA; Visco-gel Dentsply Caulk Milford, DE, USA; and Sofreliner Tough M Tokuyama Dental Corporation Tokyo, Japan) were selected. Sixty trouser-leg designed specimens per lining material were fabricated using a stainless steel mold for tear strength testing. The specimens were divided into non-thermocycling and 1000-, and 3000- thermocycling groups. For the cytotoxicity test, twenty-four disk shaped specimens per material were fabricated using a stainless steel mold. The specimens were soaked in normal saline solution for 24 h, 48 h and 72 h. Cytotoxicity was measured by XTT assay in L929 mouse fibroblasts. Data were analyzed by two way analysis of variance and Dunnett's test (P<.05).


RESULTS
Before thermocycling, Sofreliner Tough M (10.36 ± 1.00 N) had the highest tear strength value while Coe-Comfort™ (0.46 ± 0.10 N) had the lowest. After 3000 cycles, Sofreliner Tough M (9.65 ± 1.66 N) presented the highest value and Coe-Comfort™ (0.42 ± 0.08 N) the lowest. Sofreliner Tough M, in all incubation periods was the least toxic with significant differences compared to all other materials (P<.05). Coe-Comfort™, Coe-Soft™, and Sofreliner Tough M did not show any significant differences within their material group for all incubation periods.


CONCLUSIONS
This in vitro study revealed that aging can affect both the tear strength and cytotoxicity of soft denture materials depending on the composition.
Graduate School of Clinical Dentistry, Institute for Clinical Dental Research, Korea University, Seoul, Republic of Korea.
Jordi Izzard Andaya
JI
Landayan
Graduate School of Clinical Dentistry, Institute for Clinical Dental Research, Korea University, Seoul, Republic of Korea.
Adrian Carlos Francisco
AC
Manaloto
Graduate School of Clinical Dentistry, Institute for Clinical Dental Research, Korea University, Seoul, Republic of Korea.
Jeong-Yol
JY
Lee
Graduate School of Clinical Dentistry, Institute for Clinical Dental Research, Korea University, Seoul, Republic of Korea.
Sang-Wan
SW
Shin
Cytotoxicity; L929 mouse fibroblasts; Soft liner; Tear strength; Thermocycling; XTT Assay