PubMed · 4526968
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S M Ibrahim, Y Refai. 1974. Internal and external dentin resorption.. https://pubmed.ncbi.nlm.nih.gov/4526968/
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The diagnosis of root caries, in particular the judgment of the activity of a visually observed lesion, is difficult. Quantitative determination of lesion severity would allow the lesion to be monitored with time, so that an indication of lesion activity could be obtained. This paper describes a step in the development of a method that provides such a quantitative determination. Specifically, fluorescein sodium salt is used as a penetrating dye, the subject of study being the relationship between dye concentration and porosity in demineralized root dentin. Fourteen human third molars were demineralized in vitro (lactic acid CMC-gel, pH 5; in each of 6 groups for 4, 7, 11, 14, 18, and 21 days). Fluorescein sodium salt (0.2 g/L) was applied for 2 min. Thin slices (+/- 130 microns) were cut from the root surfaces without water cooling. The dye fluorescence radiance in the demineralized dentin was determined by means of a micro-Raman spectroscope and compared with the mineral loss profiles measured with transverse microradiography (TMR). The TMR data were corrected for the difference in measurement area between the two measurement systems. Corrected TMR profiles were compared with the corresponding fluorescence scans, showing linear correspondence. The correlation coefficient was r = 0.96. We conclude that, after uptake of fluorescein sodium salt for 2 min, the dye concentration in an artificially produced root-surface caries lesion is proportional to the amount of mineral lost from that lesion.
The effects of the Luxar LX-20 CO2 dental laser on resected apical root dentin were examined using stereomicroscopy and scanning electron microscopy. The surfaces of 2-mm-thick sections of dentin from freshly extracted human teeth were exposed to CO2 laser radiation. Fluences used ranged from 2.1 to 625.0 J/cm2. The effects of the laser energy on the dentin ranged from no visible effects, to charring, cracking, cratering, and glazing. The most dramatic effect was cracking. Cracking was evident on all specimens having any visible modification of the dentin. A prototype-curved laser tip was used and compared with a standard straight tip. The curved tip did not deliver laser energy to the dentin as efficiently as a straight tip. CO2 laser radiation did not consistently obliterate dentin tubules.
Most cutting and machining tools wear when properly operated on intended substrates. Little is known about endodontic files when machining on human dentin. It was shown earlier that the efficiency of files was very variable when evaluated on Plexiglas substrates. The present study of seven different brands and types of files was undertaken to understand their wear better when machining human dentin. It was shown that all files evaluated rapidly deteriorated when machining dentin. This decline in efficiency was significant but different within, as well as, among brands. It was suggested that endodontic files be disposable.