Induction of apical formation in immature teeth by different endodontic methods of treatment. Experimental pathohistological study.

summary An experimental study is described of the apex formation and structure in immature permanent teeth after vital amputation, vital extirpation and after the treatment of teeth with necrotic pulp. Experiments in young dogs suggest that after vital amputation of the coronal part of the pulp, root formation was continued through the process of changed odontogenesis. In cases where the pulp had been completely extirpated or after the treatment of pulpless teeth, the process of normal odontogenesis was interrupted and the apex was completely closed by non-homogeneous vital calcified tissue. On the basis of studies of the structure of this calcified tissue, it was concluded that it was a product of the formative activity of cells originating from the successive differentiation of fibroblasts in the young granulation tissue. The experiments suggest that following vital amputation of the pulp in children, further root odontogenesis is possible. In the treatment of pulpless teeth, the basic target should be stimulation and preservation of the formative activity of the granulation tissue cells in the apical part of the root canal to allow the possibility of calcified callus forming in the wide apical opening.