The hard tissue lesion revisited.

Recent research indicates that the thorough removal of calculus is still a critical step in the treatment of periodontal disease. Surgical access facilitates this in deep pockets. Repair is mediated by a long junctional epithelium as microscopically total calculus removal is rarely achieved. In intrabony defects the apical portion of the root surface which has not attracted deposits of calculus has the potential for connective tissue reattachment and regeneration if care is taken to preserve collagen fibres still attached to the root.