ABSTRACT
Extracted human teeth were studied to evaluate three methods of removing gutta-percha and endodontic sealer from previously obturated canals. The results showed that: (1) Each method of removal left debris in the canals. (2) Significantly more debris remained in the apical third than in the middle or coronal thirds. Likewise, significantly more debris remained in the middle than in the coronal third. (3) Use of the GPX instruments enabled gutta-percha to be removed as effectively as the other methods. (4) Use of the GPX instruments required significantly less time for gutta-percha removal, compared to removal by the other methods.
Subject(s)
Calcium Hydroxide/chemistry , Dental Pulp Cavity/ultrastructure , Gutta-Percha/chemistry , Root Canal Filling Materials/chemistry , Root Canal Preparation/instrumentation , Salicylates/chemistry , Chloroform/chemistry , Dental High-Speed Equipment , Dentin/pathology , Equipment Design , Hot Temperature , Humans , Materials Testing , Retreatment , Root Canal Irrigants/chemistry , Rotation , Sodium Chloride/chemistry , Solvents/chemistry , Surface Properties , Tooth Apex/pathologyABSTRACT
Flow cytometry is used to measure rates of ingestion of particles from dilute monodisperse suspensions by the ciliate Tetrahymena pyriformis. The particles used are polystyrene microspheres containing a fluorescent dye. Measurements were made directly, that is, by determining the fluorescence intensities from microspheres ingested by cells in samples collected from the experimental feeding apparatus. The fact that fluorescence intensities from individual cells can be grouped into discrete classes based on the numbers of fluorescent particles associated with the cells makes it possible to calibrate the flow cytometer and convert fluorescence measurements into numbers of particles ingested by average cells. At low particle concentration or high ciliate concentration, ingestion data must be corrected for depletion of particles during the assay, and a method for doing this is described. Experiments at various ciliate concentrations show that ingestion rates are not affected by this concentration. The methods developed should allow measurements of rates of ingestion of particles from concentrated and polydisperse suspensions. For such measurements, nonfluorescent particles together with a fraction of fluorescent tracer particles would be used.
