Sorption of three 125I-labeled human proteins (albumin, immunoglobulin G, and lysozyme) to enamel and cementum was investigated. All three proteins sorped most when suspended in 0.0005 M solution of phosphate or calcium chloride where the least competition between solute ions and label occurred. The addition of human serum to labeled proteins caused a decrease in their sorption which could be partially reversed by increasing the concentration of label. Kinetic experiments demonstrated that sorption was dependent on protein concentration and incubation time and that most of the sorption occurred within the first minute of the reaction. In conclusion, the binding of the three labeled proteins was affected by the charge of the solute ions and was dependent on ion concentration and reaction time. Sorption correlated for the most part with the pK values of the proteins and thus lysozyme, the most basic protein, sorped more than immunoglobulin G, which sorped more than albumin. In all cases, cementum bound more basic protein than did enamel. Increased levels of albumin sorption to enamel occurred when the protein was suspended in the CaCl2 solution rather than in phosphate. In addition, based on Scatchard analysis, approximately twice as many potential protein binding sites were found for cementum versus enamel.

The purpose of this study was to determine the conditions that favor the sorption and retention of human plasma fibronectin to cementum. Rectangular root segments prepared from teeth extracted for orthodontic reasons were mounted on a capillary pipette and immersed in solutions of 125I fibronectin for assay of cementum sorption under various conditions. Kinetic studies showed sorption to be rapid, with 77% of the maximum fibronectin sorption occurring within 1 minute. Fibronectin sorption was reduced when added in conjunction with serum and was inhibited by monovalent ions (such as sodium), but enhanced in the presence of divalent cations (such as calcium). Exposure of cementum to serum partially blocked subsequent sorption of fibronectin, while cementum bound fibronectin was eluted by subsequent exposure to serum. Treatment of cementum with citric acid pH 1.1 (4 minutes) followed by 5% sodium hypochlorite (5 minutes) caused a significant increase in fibronectin sorption with maximum retention upon subsequent exposure to serum (P <0.05). Fibronectin sorption to cementum was: rapid, electrostatic in nature, competitive, reversible, Ca++ ‐facilitated, and maximized by prior treatment of the root with citric acid and sodium hypochlorite. It is concluded that sorption of fibronectin to cementum can be achieved for clinical gain; however, conditions of application can significantly influence both accumulation and subsequent release of root sorbed material. J Periodontol 1990; 61:254–260.

The nature of the interaction between root surfaces and gingival fluid proteins has not been studied. Therefore, a series of in vitro investigations were undertaken to develop an assay to determine sorption of prominent gingival fluid proteins to the cementum. In initial studies extracted teeth were immersed in various concentrations of whole human serum and incubated with rabbit anti‐IgG, IgA, IgM, and C3 followed by anti‐peroxidaseperoxidase bridging reagents. Of the proteins analysed IgG sorbed to the highest degree in gross and microscopic evaluations. Remaining studies focused on quantifying IgG sorption, and thus root segments of known surface area were prepared and immersed in 125I‐IgG. Sorption of IgG was calculated as 21.5 ± 0.27 ng/mm2 when IgG was added at concentrations found in gingival fluid. Root fragments immersed in non‐IgG human serum reconstituted with specific amounts of 125I‐IgG, sorped only 3.4 ± 0.9 ng/mm2 of IgG, and direct measurement of IgG sorption in whole serum by the ELISA method gave comparable results. Moreover, pre‐coating of root segments with non‐IgG serum followed by incubation with 125I‐IgG resulted in 74% inhibition of IgG binding. Results suggest that serum protein sorption to root surfaces can be quantitated and may be non‐specific and concentration dependent with respect to IgG.