Healing following citric acid conditioning of roots implanted into bone and gingival connective tissue

The aim of the present investigation was to examine if a new connective tissue attachment is established following citric acid treatment of previously periodontitis involved roots, transplanted and placed in contact with gingival connective tissue or bone during healing. Periodontal tissue breakdown was produced around the mandibular third and fourth premolars in six beagle dogs by the placement of cotton floss ligatures around the neck of the teeth. When the destruction of the supporting tissues had progressed to the mid‐root level, the ligatures were removed. Following resection of the crowns, the teeth were root filled and the exposed parts of the roots thoroughly scaled and planed during a flap procedure. Half the number of the teeth were subsequently treated with citric acid at pH 1 for 3 min while the remaining teeth were treated with sterile saline for the same period of time. Each root was extracted and implanted into grooves prepared in edentulous areas of the jaws in such a way that the root was embedded to half its circumference into bone, leaving the remaining part to be covered by the connective tissue of the repositioned flap of the recipient site. After a healing period of 2 months, an analysis of histological specimens, obtained from biopsies of the recipient site tissues, disclosed that new connective tissue attachment failed to form on the previously periodontitis involved roots whether or not these roots had been subjected to citric acid conditioning. On the contrary, healing consistently resulted in extensive resorption of the roots. The results indicate that citric acid does not alter the biological ability of bone and gingival connective tissue to induce root resorption.