Journal of Dental Research, Vol 70, 211-214, Copyright © 1991 by International & American Associations for Dental Research Online Journals
Dentin-bonding molar efficiency using N-phenylglycine, N-phenyl-beta-alanine, or N-methyl-N-phenylglycine
R. E. Webb and A. D. Johnston
Naval Dental School, NNDC, Bethesda, Maryland 20814-5077.
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.
