EVALUATION OF RETENTION AND MICROBIAL COLONIZATION OF TWO DIFFERENT DENTURE BASE MATERIAL

The aim of this study: Is to evaluate the effect of conventional heat cure acrylic resin denture base and thermoplastic resin base on the retention and bacterial colonization in complete dentures.
Material and methods: Twenty completely edentulous patients were selected and randomly grouped into two equal groups: group I received maxillary and mandibular complete dentures made of conventional heat-cured acrylic resin, group II received maxillary and mandibular complete dentures made of thermoplastic resin. The retention mean values were measured for mandibular dentures for both groups at time of denture insertion and after 3 months by using the universal testing machine. Assessment of microbial colonization in the two denture base materials was done after 3 and 6 months from denture insertion. The isolation of microorganisms was done with gamma sterilized disposable swabs from tuberosity area under the fitting surface of the maxillary dentures, each swab cultivated in three culture media. The tested microorganisms are Candida albicans (C. albicans), Streptococcus mutans (S. mutans), Staphylococcus aureus (S. aureus) and mixed Streptococcus and Candida.
Results: The thermoplastic resin denture showed statistically significant higher mean of retention value than conventional heat cure denture at insertion and after 3 months (P value <0.000). The microbial colonization results revealed significant difference between group I and group II in the count of C. albicans, S. mutans and mixed Streptococcus after 3 months and 6 months. The thermoplastic resin base (group II) showed decreased microorganism count than group I (heat cured acrylic resin base) while S. aureus count showed no statistically significant difference between the two groups.
Conclusion: Thermoplastic resin denture bases showed better retention and less microbial colonization than conventional heat cure acrylic resin. Further studies are recommended to evaluate the long-term quality of retention and biological properties of thermoplastic resin complete dentures and its impact on patients’ satisfaction.