A protocol for determining the surface free energy of dental materials.
OBJECTIVE
The purpose of this study was to develop a standard methodology for measuring the surface free energy (SFE), and its component parts, of dental biomaterials.


METHODS
The contact angle of each of four samples of two materials--low density polyethylene and poly(methyl methacrylate)--was measured three times in each of six liquids (1-bromonaphthalene, diiodomethane, ethylene glycol, formamide, glycerol and distilled water). Critical surface tension estimates were obtained from Zisman plots. Data were then analyzed by the least-squares method to estimate the components of SFE. Estimates were also made for each of 12 liquid triplets, and by maximum likelihood and Bayesian analyses.


RESULTS
The use of liquid triplets could yield misleading estimates of the components of SFE. A testing protocol is suggested in which multiple test liquids are used, and multiple methods of statistical analyses employed.


CONCLUSIONS
SFE is important, in that high SFE is desirable when adhesion is required, but undesirable if plaque resistance is needed. Methodology that avoids some of the limitations of existing studies has been proposed.
Combe
Edward C
EC
Minnesota Dental Research Center for Biomaterials and Biomechanics, University of Minnesota School of Dentistry, 16-212 Moos Tower, 515 Delaware Street SE, Minneapolis, MN 55455, USA. combe001@umn.edu
Owen
Brandon A
BA
Hodges
James S
JS
D001499:Bayes Theorem; D003764:Dental Materials; D019855:Ethylene Glycol; D005559:Formamides; D005990:Glycerol; D006847:Hydrocarbons, Iodinated; D016018:Least-Squares Analysis; D016013:Likelihood Functions; D008422:Materials Testing / Q000379:methods; D009281:Naphthalenes; D020959:Polyethylene; D019904:Polymethyl Methacrylate; D013499:Surface Properties; D013500:Surface Tension; D013816:Thermodynamics; D014867:Water; D017155:Wettability
D003764:Dental Materials; D005559:Formamides; D006847:Hydrocarbons, Iodinated; D009281:Naphthalenes; D014867:Water; C027946:methylene iodide; C031066:formamide; C108222:alpha-bromonaphthalene; D020959:Polyethylene; D019904:Polymethyl Methacrylate; D019855:Ethylene Glycol; D005990:Glycerol