Molar Efficiency Study of Chlorinated NPG Substitutes in Dentin Bonding

Abstract

This study evaluated and compared the contributions to dentin adhesive bonding of three N-phenylglycine analogues with electron-withdrawing substituents on the aromatic ring. These electron-deficient "N-compounds" included: N-(4-chlorophenyl)-glycine (NCPG), N-methyl-N-(4-chlorophenyl)-glycine (NMNCPG), and N-(3,4-dichlorophenyD-glycine (NDCPG). An experimental three-step dentin-bonding protocol that consisted of sequential application of acidic ferric oxalate solution, an N-compound in acetone, and a surface-active comonomer in acetone was used. The first and third steps were held constant throughout the study. EachN-compound (NCPG, NMNCPG, NDCPG) was used in step two at ten concentrations ranging from 0.0 mol/L (pure acetone) to 5 x 10^-1 mol/L, depending on solubility. After overnight storage in distilled water, the dentin-to-composite bonds were broken in tension. The data were analyzed with ANOVA, and multiple comparisons were performed with Duncan's Multiple Range test. All statistical tests were controlled at α = 0.05. At 5 x 10^-3 mol/L, the relative effectiveness of the three N-compounds (as measured by tensile bond strengths) was NMNCPG > NCPG > NDCPG. Of all concentrations studied, the mean bond strengths produced with NMNCPG were statistically as good as or better than those produced by the other two compounds, and NCPG was always as good as or better than NDCPG. Increased electron-withdrawing from the nitrogen of the amine group by the substituents narrowed the effective concentration range for dentin bonding and, in general, produced lower mean bond strengths between dentin and composite.

Get full access to this article

View all access options for this article.

References

Baker W. , Ollis WD , Poole VD (1949). Cyclic meso-ionic compounds. I. The structure of the sydnones and related compounds. J Chem Soc 307-314.

Blosser RL , Bowen RL (1988). Effects of purified ferric oxalate/nitric acid solutions as a pretreatment for the NTG-GMA and PMDM bonding system. Dent Mater 4:225-231.

Borch RF Hassid AI (1972). A new method for the methylation of amines. J Org Chem 37:1673-1674.

Bowen RL (1965). Adhesive bonding of various materials to hard tooth tissue. I. Method of determining bond strength. J Dent Res 44:690-695.

Bowen RL , Cobb EN , Rapson JE (1982). Adhesive bonding of various materials to hard tooth tissues: Improvement in bond strength to dentin. J Dent Res 61:1070-1076.

Bowen RL , Cobb EN , Misra DN (1984). Adhesive bonding by surface initiation of polymerization . Ind Eng Chem Prod Res Dev 23 :78-81.

Bryson A. , Davies NR , Serjeant EP (1963). The ionization constants of N-(substituted-phenyl)-glycines . J Am Chem Soc 85 :1933-1938.

Chen R. -S, Bowen RL (1989). The use of N-phenylglycine in a dental adhesive system. J Adhes Sci Technol 3:49-54.

Cobb EN , Blosser RL , Bowen RL , Johnston AD (1989). Ferric oxalate with nitric acid as a conditioner in an adhesive bonding system. J Adhesion 28:41-49.

10.

Duncan DB (1955). Multiple range and multiple F tests. Biometrics 11:1-45.

11.

Farahani MF , Johnston AD , Bowen RL (1991). The effect of catalyst structure on the synthesis of a dental restorative monomer. J Dent Res 70:67-71.

12.

Johnston AD , Asmussen E. , Bowen RL (1989). Substitutes for N-phenylglycine in adhesive bonding to dentin. J Dent Res 68 :1337-1344.

13.

Neter J. , Wasserman W. , Kutner MH (1990). Multifactor analysis of variance. In: Applied linear statistical models. Homewood (IL): Richard D. Irwin, Inc., 686-687.

14.

SAS Institute, Inc. (1987). SAS/STAT software and user's guide. Release 6.0 3ed. Cary (NC): SAS Institute, Inc.

15.

Schwalbe CG , Schultz W. , Jochheim H. (1908). w-chloracetanilide and certain halogen phenylglycines . Berichte Deutsch Chem Ges 41:3790-3796.

16.

Wall FJ ( 1986). Duncan's multiple comparisons test. In: Statistical data analysis handbook. New York: McGraw-Hill, Inc., 4.10-4.11, 15.3.

17.

Webb RE , Johnston AD (1991). Dentin bonding molar efficiency using N-phenylglycine, N-phenyl, beta-alanine, or N-methyl, N-phenylglycine. J Dent Res 70:211-214.