Effects of a supersaturated pulpal fluid on the formation of caries-like lesions on the roots of human teeth.

Root surfaces were exposed to demineralizing buffer in a continuous-flow system, with or without simultaneous perfusion of the pulp chamber with a supersaturated surrogate dentine fluid (SDF). Experimental lesions formed with perfusion of the pulp were significantly less deep than control lesions formed without perfusion, but the application of hydrostatic pressure to the SDF (15 or 30 cm water) did not produce significantly greater reductions. The lesion depth reduction was attributed to reduced undersaturation at the advancing lesion front through interdiffusion of the demineralizing buffer and the SDF. Translucent bands, resembling sclerotic dentine, were observed beneath 9 of 24 experimental lesions and 5 of 24 control lesions. Scanning electron microscopy showed that, in most of the bands beneath experimental lesions, dentinal tubules were either partly occluded by granular mineral deposits or were reduced in diameter. Thus, in vivo, dentine fluid may modify the rate of lesion progression and promote sclerosis in the underlying dentine.