An In-vitro Evaluation of Retention, Colonization and Penetration of Commonly Used Denture Lining Materials By Candida albicans

Introduction: Colonization of the surface by Candida albicans and related Candida species is one of the major concerns of denture lining materials. Aim: We evaluated retention, colonization and penetration of the four denture lining materials namely Molloplast B, Permaflex, GC Soft Liner and Ufi Gel Hard C by Candida albicans. Material and Methods: a) Evaluation of retention: Five test discs of each material with smooth surface on one side and rough on the other were prepared and surface roughness (Ra) was measured with profilometer. Retention of C. albicans to discs was monitored after one hour of incubation (37 degrees C) with standardized (2.8 x 10(6) cfu/ml) washed cell suspension. Discs were stained with acridine orange and attached cells were counted using inverted microscope; b) Evaluation of colonization and penetration: Eight test discs of each material in sterile artificial saliva, were inoculated with C. albicans and incubated for six weeks. Two sections were cut across each test disc to provide three replicate samples. Candida cells on cut disc sections were fixed, dehydrated, air dried and viewed via fluorescence microscope; c) Evaluation of antifungal action: Two test discs of each material were placed onto diagnostic sensitivity testing the agar plate. After incubation at 37 degrees C for 24 hours, the zone of inhibition formed around the samples were measured at four places, and the mean calculated. Results: a) All rough surfaces showed higher retention of C. albicans than smooth surfaces. Among the smooth surfaces, Molloplast B and GC Soft Liner showed highest and lowest retention of C. albicans respectively (p=0.0090). Among the rough surfaces, the variation in the retention of C. albicans was not statistically significant; b) Penetration of C. albicans was observed through all three sections of the test discs of each material. There was no statistically significant difference among the test materials; c) Molloplast B and Permaflex produced a mean zone of inhibition of 16.9 +/- 4.8mm and 14.80 +/- 3.8mm respectively. Conclusion: a) Smoother surfaces retain fewer cells than rough surfaces; b) Denture lining materials permit infiltration of Candida through their structure; c) Denture lining materials have insignificant anti-fungal properties.