Effect of tea tree oil addition to soft lining materials on candida albicans inhibition and bond strength of materials to acrylic denture base

Colonization of C. albicans to soft lining; it is the primary factor in the development of prosthetic stomatitis. Aim of this study is to investigate the effect of tea tree oil mixed with soft liner materials on C. albicans and bond strength of soft liners to an acrylic resin denture base. Different proportions of tea tree oil (0%, 2%, 5%, 8%), was addition to four different soft lining materials (Tokuyama, Gc, Visco-gel, Molloplast B) to prepare microbiological test samples. Samples were sterilized with ultraviolet and stored in artificial saliva for 24 hours then transferred to Sabaroud broth medium containing C. albicans. At the 24th and 48th hours of the incubation, the density of C. albicans was measured with a spectrophotometer. The dilute solution, was spread over the petri dish containing Sabaruod dextrose agar after serial dilution. The colony count was made 48 hours later. For the tensile bond strength test, samples were prepared with heat polymerized acrylic in ASTM D638 standards. A 3 milimeter piece was removed from the samples, four different soft lining materials mixed with tea tree oil in different proportions, were placed in space. Tensile test was applied to the samples at a speed of 5 mm/min. Failure types were classified (adhesive, cohesive, mixed), rupture surfaces were examined with the aid of SEM. SPSS 17.0 Windows was used for statistical analysis. The compliance of the data to the distribution of normality was evaluated using the Shapiro Wilk test. Two-way ANOVA, Bonferroni correction, paired sample t-test were performed to evaluate data. p<0,05 level was considered significant in all analyzes. The type of soft lining materials used in our study and the ratio of tea tree oil created a statistically significant difference on the density of C. albicans, colony numbers and the bond between acrylic base (p<0,01). As the proportion of tea tree oil increased; C. albicans density, colony number and bond strength of soft linings decreased (p>0,05). The lowest density and colony number values of C. albicans were observed in the Tokuyama and Gc soft lining materials. The bond strength of the Gc lining material were found to be the highest in all proportions of tea tree oil when compared to the other materials (p<0,01). Key words: Soft liner materials, Tea tree oil, Candida albicans, Bond strength