The Effect of Virgin Coconut Oil Addition on the Hardness and Wettability of Acrylic Based Denture Soft Lining Material
Maintaining an ideal hardness value during the long term use of soft liner is very difficult, because soft liner material will lose some of its components and gain others, this will adversely affect its properties. The aim of the current study was to evaluate the effect of virgin coconut oil addition on the hardness of heat-cured acrylic based soft denture liner material. In addition, to investigate the wettability of the material after this incorporation. Both investigations were conducted at different periods of time.
Material and method: one hundred eighty samples were prepared by the addition of 1.5% and 2.5% (by volume) of virgin coconut oil into acrylic-based heat cured soft denture lining material. The study samples were divided into two groups (90 samples for each group) according to the conducted test; hardness and wettability tests. Then each group was further subdivided into three subgroups (control 0%, 1.5% and 2.5%) according to the concentration of the incorporated coconut oil (n=10 samples for each subgroup). Each group was assessed at different time intervals (1 day in distilled water, 14 and 30 days in artificial saliva), ten samples were used for each time interval. Fourier transform infrared analysis was used to detect if there is any chemical reaction between soft lining material and coconut oil.
Results: Shore A hardness test demonstrated a reduction in the mean value of hardness after adding 1.5% and 2.5% coconut oil in comparison to the control group, this reduction was highly significant after 24 hours incubation in distilled water. The results revealed a fluctuating behavior at different time intervals in which the values showed an increase followed by a decrease in the hardness after incubation in artificial saliva for both 2 and 4 weeks. Regarding the wettability test, the results revealed a reduction in the contact angle values after 24 hours and 2 weeks of incubation intervals, this reduction was highly significant for the 1.5% group (p<0.01). While after 4 weeks of incubation, the mean values of contact angle of the experimental groups were increased. Conclusion: Virgin coconut oil was successfully incorporated into the soft denture liner and revealed an improvement in the material softness and wettability.