Thesis (M.Sc.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Operative Dentistry

The study was performed to assess the efficacy of caries excavation using the papain-based chemo-mechanical method (Brix 3000) in comparison to conventional rotary tools in the reduction of Streptococcus Mutans count in Occlusal carious cavities. Materials and methods: Double-blinded, two-armed, split-mouth and a randomized clinical trial was conducted in the clinic of the Conservative Dentistry Department, Faculty of Dentistry, Cairo University, Egypt. Twenty-three patients aged between 18-40 years with active carious lesions in a permanent lower molar (each patient had at least two cavitied molars) were randomly allocated into two groups: a test group (N=23): Brix3000 and a Control group (N=23): Conventional rotary. From each group, two dentin samples were collected before and after caries removal. In both groups, the central cariogenic biomass and superficial parts of the necrotic dentin was removed with the excavator and then discarded. Then, a dentin sample was collected using a sharp, sterile excavator. And then the dentin samples were immediately transferred to the sterile disposable test tube containing 1.5 ml thioglycollate medium used as a carrier and kept in an icebox then taken to the microbiology laboratory for processing within two hours. The sterilized bottles containing the dentin samples were shaken in a vortex for the 30s to disperse bacterial aggregates and decimal dilutions were then prepared in sterile saline (0.9% NaCl). Next, 50 ol aliquots of each dilution were spread using micropipette onto the following solid media and spread on the surface of the agar using a sterile glass rod to give homogenous bacterial growth. Mitis salivarius agar (MSA) was used for Streptococcus spp

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