Effect of mechanical removal of the pulp upon the retention of odontoblasts around the pulp chamber of human third molars

The pulp chambers of 11 freshly extracted human third molars were exposed by cutting off the roots apical to the cervical margin and the pulps were either removed with forceps and discarded or left in situ. The teeth were fixed, demineralized, divided longitudinally, embedded in resin and 2-μm sections stained with toluidine blue were examined by light microscopy. In pulp-removed specimens the percentage retention of the odontoblast layer with the predentine varied near the longitudinal division but when sectioned deeper all six specimens displayed 100% retention. The intactness of the retained odontoblast layer was mostly good as judged by the mutual close apposition of the distal ends of the cell bodies and their relation to the predentine. The retention of the odontoblast layer with the predentine may be due to the distribution of fibronectin, which others have shown is present between odontoblasts, and between odontoblasts and predentine, but lacking beneath the odontoblast layer.