New attachment formation on citric acid treated roots

The present investigation was carried out in order to examine if citric acid treatment would promote new attachment formation on roots with a reduced but healthy periodontium. In each of 4 monkeys, periodontal tissue breakdown was induced around a maxillary and mandibular central incisor and second premolar or first molar by placing orthodontic elastic ligatures around the teeth. The ligatures were kept in situ until about 50% of the supporting tissues had been lost. Three months following removal of the ligatures the crown of the teeth was resected. The pocket epithelium and subjacent granulation tissue were excised and the periodontitis involved part of all roots was root planed using a diamond bur. Half the number of the teeth (7 teeth, i.e. II test roots) were treated by topical application of citric acid at pH 1 for 3 minutes. All roots were covered with a mucosal flap. The animals were sacrificed after 3 months of healing. The jaws were removed and tissue blocks containing the roots and their surrounding tissues were processed for embedding in paraffin. Serial sections, 8 μm thick, were cut in mesio‐distal direction for microscopic analysis. Six citric acid treated roots and 6 noncitric acid treated roots penetrated the covering soft tissue flap within the first week of healing. The microscopical analysis disclosed that in all roots new cementum with inserting collagen fibers had formed in the apical portion of the previously periodontitis involved surfaces. In those control roots, which for the entire length of the study remained covered by the oral mucosa, the coronal extension of this newly formed fibrous attachment amounted to an average of 1.0 mm with a range between 0.1 mm and 2.6 mm, and in the corresponding test roots 1.1 mm with a range between 0.1 mm and 2.2 mm. The length of the newly formed connective tissue attachment was significantly smaller in those test and control roots which had penetrated the soft tissue flap during healing than in those which remained covered throughout the study. No statistically significant difference was found between citric acid and non‐citric acid treated roots with respect to the amount of newly formed connective tissue attachment.