Evaluation the Effect of Chemical Disinfectants on Denture Base Resin and Testing of Their Effect in Hardness and Surface Ruoghness: An In vitro Study.

Abstract

Introduction; Acrylic resin (PMMA) is extensively used material in different branches of dentistry. Most dentures are made up from acrylic resins because of its ease of manipulation and low price, in spite of its benefits, PMMA is not an ideal material, with surface roughness, discoloration and hardness being three drawbacks.Accumulation of biofilm as a consequence of poor denture hygiene, which in turn leads to onset of several systemic and oral infections.Denture cleansing is necessary for removal of biofilm from dentures. Denture cleansing can be achieved mechanically by manual brushing, chemically involving wide varieties of chemical agents, and by combination of both. Aims:The current study aimed to evaluate the effect of three types of disinfectants (5% sodium hypochlorite, 00.12% chlorahexidine and 6% hydrogen peroxide) on elimination of (C.albicans ,Staph, Aures and Strept. Mutans) from heat-cure acrylic resin surface by 10 minutes immersion and in the same time study of their effect on hardness and roughness of denture surface. Material and Method:The samples were prepared using a putty former filled with base plate wax, then invested with a dental stone in metallic dental flasks. The resin was manipulated according to the manufacturer’s instructions. Polishing was done in one surface of the samples, and the other surface was left unpolished. The microorganism has been clinically isolated by swab from oral cavity and allowed to grow in their selected culture using incubator. Specimens were separately placed in petri-dishes with respective culture. The samples has been divided into three main groups according to types of disinfectant, all samples has been placed again into incubator for 24h to allowing the microorganism grow over the rough surface. Then, each group divided again into three subgroups. Each sub group contains six samples. Five samples for each sub-group were colonized in the laboratory by, Staphylococcus aureus , Streptococcus Mutans ,and Candida Alibicans spp. Respectively, the remained single sample will be considered as control sample. After colonization of microorganisms each group has been disinfected by corresponding disinfectant for 10 minutes, and then incubated again for 24 hours. After that the petri-dishes with samples were checked for re-colonization of microorganism as respect to disinfectant agent. The hardness test was also evaluated by Vicker test machine after 10 minutes of immersion in disinfectant. The roughness has been evaluated by surface profilometer. Results: The microbiological test had shown that all selected microorganisms have been eliminated by all disinfectants except strept., which shown a resistance to hydrogen peroxide. all disinfectants shown a significant difference in comparison to control samples which was immersed in distilled water, this was for both hardness and surface roughness. However, there was no significant difference between tested groups. Conclusion: From economic point of view the 5% sodium hypochlorite is cheaper than the other disinfectants and it is available in every market whereas, the other disinfectants (chlorahexidine and hydrogen peroxide) are more expensive and only found in certain places. Therefore, it can be recommended that the 5% sodium hypochlorite is most appropriate disinfected agent in prosthodontics to clean dentures; this finding was supported and approved by many researchers.