Buonacuore

buiJournal of Dental Research
http://jdr.sagepub.com A Simple Method of Increasing the Adhesion of Acrylic Filling Materials to Enamel Surfaces
Michael G. Buonocore J DENT RES 1955; 34; 849 DOI: 10.1177/00220345550340060801 The online version of this article can be found at: http://jdr.sagepub.com

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A SIMPLE METHOD OF INCREASING THE ADHESION OF ACRYLIC FILLING MATERIALS TO ENAMEL SURFACES
MICHAEL G. BUONOCORE, D.M.D., M.S. Eastman Dental Dispensary, Rochester, N. Y.

ONE of the major shortcomings of the acrylics and other filling materials
is their lack of adhesion to tooth structure.'-4 A filling material capable of forming strongbonds to tooth structures would offer many advantages over present ones. With such a material, there would be no need for retention and resistance form in cavity preparation, and effective sealing of pits, fissures, and beginning various lesions could be realized. In our attempts to obtain bonding between filling materials and tooth structure, several possibilities are being explored. These include(1) the development of new resin materials which have adhesive properties; (2) modification of present materials to make them adhesive; (3) the use of coatings as adhesive interface materials between filling and tooth; and (4) the -alteration of the tooth surface by chemical treatment to produce a new surface to which present materials might adhere. This last approach is the subject of this paper,but since it concerns itself only with treatment of intact enamel surfaces, it has only limited application to the broader problems of restorative dentistry. In industry, phosphoric acid and preparations containing it have been used to treat metal surfaces to obtain better adhesion of paint and resin coatings.5 Although the increased adhesion is believed to be due primarily to the removal ofsurface and other contaminants, the conversion of the oxides or the surface of the metal itself to phosphates or the adsorption of phosphate groups on the metal surface may contribute to the effect. Since the enamel surface has probably reacted with various ions, saliva, and so on, to which it has been exposed for long periods of time, and its tiny imperfections filled in by a variety of adventitiousmaterials, the composition of the superficial surface may be quite different than the underlying enamel.6 As a result, any receptivity to adhesion which the original tooth structure may have had for acrylic materials may have been lost. It was felt that perhaps an acid treatment of the enamel surface might render it more receptive to adhesion in the same manner as it does for metals.
EXPERIMENTALTwo methods were used for treating the enamel surfaces. The first involved the use of a 50 per cent dilution of a commercial phosphomolybdate
This investigation was supported by the Medical Research and Development Board, Office of the Surgeon General, Department of the Army, under Contract No. DA-49-007-MD-330. Received for publication July 14, 1954.

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reagent containing sodium tungstate (Folin-Wii) in conjunction with a 10 per cent oxalic acid solution; the second, the use of an 85 per cent phosphoric acid solution. By using the phosphomolybdate-oxalic acid treatment, we hoped to produce a surface chemically different from that existing normally in enamel. It was felt that the...