[Effect of remaining dentine thickness beneath deep cavities on the rate of reparative dentine...

The aim of this study was to investigate the effect of remaining dentine thickness beneath deep cavities on the rate of reparative dentine formation throughout 119 days and to establish the limit value of the remaining dentine thickness that enables greatest amount of tertiary dentine in dogs' teeth. Deep buccal cavities were prepared in all canines and molars of three dogs, lined with four different lining materials for indirect pulp capping and filled with silver amalgam. Tetracycline labelling technique was used to demark the layers of reparative dentine produced during the experimental period of 17 weeks. After sacrificing and isolation the teeth from the jaws slices (1 mm thick) were cut off through the middle of the cavity, perpendicular to the cavity floor and mesio-distal tooth axis. Sections were ground to 100 microns thick; the measuring of the remaining and reparative dentine thickness was carried out with Fluoval, Carl-Zeiss, Jena, DDR fluorescent microscope. The results showed: 1. Cavity depth had a strong effect on the quantity of newly formed tertiary dentine; 2. The greatest rate of reparative dentine (348 microns) was produced beneath the cavities with remaining dentine thickness ranging 501-700 microns; 3. The least quantities of tertiary dentine (219 and 227 microns) were produced beneath the deepest cavities, with remaining dentine thickness less than 500 microns, as well as beneath shallower cavities with remaining dentine thickness of over 900 microns.