Dentin-bonding molar efficiency using N-phenylglycine, N-phenyl-beta-alanine, or N-methyl-N-phenylglycine.
Three structurally related substituted amino acids (N-compounds) were studied in a three-step dentin-bonding protocol. The first step of an acidic ferric oxalate solution and the third step of a surface-active comonomer were held constant throughout the study. In the second step, the amount of the N-compound--either N-phenylglycine (NPG), N-methyl-N-phenylglycine (NMNPG), or N-phenyl-beta-alanine (NPBA)--was varied in acetone from 0 mol/L through 5 x 10(-1) mol/L in seven steps. At 1 x 10(-3) mol/L for NPG and NMNPG, average bond strength values were 7.4 +/- 2.2 and 10.5 +/- 2.7 MPa. The highest bond strength value for NMNPG was at 1 x 10(-2) mol/L, with 13.2 +/- 4.0 MPa. The highest value for NPG was at 1 x 10(-1) mol/L, with a value of 11.8 +/- 2.5 MPa. The average bond strength for NPBA did not differ from zero across the entire range of concentrations. Molar efficiency was defined as the bond strength per mole of these applied N-compounds. For the two N-compounds that did provide adhesion to dentin, NPG and NMNPG, the average bond strengths rose, peaked, and fell as the amounts of applied N-compound were increased. The molar efficiency dropped off as the concentration of applied N-compound rose. The least operator-sensitive and most efficient N-compound, NMNPG, delivered a bond strength equivalent to that of NPG, with 10% of the applied NPG amount.
Webb
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Naval Dental School, NNDC, Bethesda, Maryland 20814-5077.
Johnston
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D000269:Adhesives / Q000737:chemistry; D000704:Analysis of Variance; D003188:Composite Resins; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D003799:Dental Stress Analysis; D003804:Dentin; D005998:Glycine / Q000031:analogs & derivatives*; D006801:Humans; D008422:Materials Testing; D013718:Tensile Strength
D000269:Adhesives; D003188:Composite Resins; D003738:Dental Cements; C021316:N-phenylglycine; D005998:Glycine