Human clinical and histologic repair responses following the use of citric acid in periodontal therapy.

Seven blocks containing one tooth each were obtained from two patients undergoing treatment for periodontitis. Sixteen weeks prior to block removal, these sites were treated by periodontal flap surgery. In six teeth a citric acid solution (pH = 1) was applied for 2 minutes to the planed root surfaces. The seventh tooth received identical periodontal therapy except that saline was applied to the planed root for 2 minutes. At the end of the experimental period, the blocks were removed and prepared for histologic study. In five out of six citric acid treated specimens, no evidence was observed suggesting that citric acid applications either initiated or accelerated cementogenesis or functional connective tissue attachment at root surfaces previously exposed to periodontal pockets. In one specimen, repair cementum was seen crestally to the alveolar margin. This cementum was deposited on the surface of acellular cementum. Unfortunately, however, the specimen does not allow us to date the deposition of the repair cementum. It thus remains questionable whether this cemental deposition is indeed a repair response to the specific treatment performed.