Microbial Sampling of Carious Dentin

Caries,Dental

The School of Dentistry is seeking to determine whether viable microorganisms remain within tooth structure after conventional, mechanical removal of areas of tooth decay, prior to placement or replacement of tooth restorations (fillings). The long-term goal of the work is to decrease the failure rate, and therefore increase the longevity, of tooth restorations (fillings) in human patients and populations.

It is proposed that with informed consent, and in a sterile operating environment (controlled, micron level-filtered environmental air flow, in addition to conventional instrument sterilization) dental patient volunteers will have either areas of decayed tooth structure or recurrent caries defective fillings removed using conventional, routine procedures, which will include: local anesthesia; tooth isolation using rubber dam; removal of superficial decay, weakened tooth structure or defective filling materials with rotary tooth cutting instruments; and then removal of softened dentin using sterile sharp spoon excavators, by hand. The limit of dentin removal will be determined by the clinician's estimate of tooth hardness, that is, using present conventional and ethical practice. This last step, removal of tissue guided by estimated hardness, is as described above the universally accepted standard. Following removal, the exposed dentin surface will be examined visually with an 15X operating microscope to detect any areas of discolored dentin. Any such areas will be micro-sampled using ultra slow-speed, 0.2 mm diameter rotary cutting instruments and removal of resultant dentin flakes with sterile fibers. Each prepared cavity will then be restored using conventional tooth filling materials and techniques. Immediately after removal each dentin flake will be weighed, placed into bacterial transport medium, then sonicated. The transport medium will be divided in two, and separate samples added to bacterial growth medium under anaerobic and aerobic growth conditions. Any viable microorganisms detected will be identified both by conventional plating techniques using visual identification, and by a commercial laboratory using RNA analysis.

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