Western Society of Periodontics

Laboratory Studies

Volume Number 4, 1995

Effects of citric acid treatment on the Ca, P, and Mg contents of human dental roots

The effects of citric acid application have been extensively debated. Arguments in favor of its use state that citric acid can elute bacterial endotoxins or remove the smear layer. The uncovered collagen matrix is thought to provide a substrate which supports the chemotaxis, migration, and attachment of the periodontal cells. But what is uncertain for these authors is the amount of demineralization that will occur if the tooth itself is at different layers such as dentin, cemental dentin, or cementum created by previous procedures, such as scaling and root planing. Thus, considering that during the periodontal therapy the mechanical root planing reveals some more internal layers of the root, it is important to consider the effects of a citric acid solution on these differently mineralized tissues. The authors feel that different layers within the cementum, dentin, and their junction will demineralize at different rates, thereby affecting the abilities of this treatment and providing a reason why its clinical use is unpredictable.

To conduct this study, 25 sound human third molars extracted less than two months previously were used for treatment. Transverse sections were made and polished to remove the conductive carbon layer. Each sample of the test group was placed in 10 ml of the citric acid solution for two minutes. Results indicated that the "tooth" factor does not influence the Ca losses while it evidently affects dissolution of P and Mg elements. The citric acid solution led to demineralization of dentine and cementum surfaces, and this demineralization depended on the level inside the root. For example, it was shown that external dentin demineralized less than internal dentin. The authors conclude that the unsuccessful periodontal repairs after citric acid treatment maybe due to the properties of the external layer of dentine, justifying additional scaling and root planing during surgery to remove this layer. [D.H.]