ENHANCED PERMEABILITY OF ACID-ETCHED OR GROUND DENTAL ENAMEL

Statement of problem. Acid etching creates retentive microcraters on e namel surfaces. Designing of a partial denture often involves reshapin g the supporting and retentive teeth by grinding the enamel. Unfortuna tely, both these procedures damage the enamel surface. In vivo such su rface damage takes several months to recover. Purpose. This study eval uated the effect of 1-minute etching, prolonged etching, and grinding on the permeability of dental enamel for water-soluble molecules. Mate rial and methods. With the electron paramagnetic resonance and a two-c hamber diffusion cell, the influence of etching and grinding on the di ffusion of spin label molecules through the enamel was studied quantit atively. The enamel permeability was measured in 30 sound enamel sampl es, of which 10 samples were exposed to 1-minute etching with 37% phos phoric acid, 10 samples were etched for 5 minutes, and 10 samples were ground with a diamond bur. Results and Conclusions. All procedures si gnificantly increased the permeability of dental enamel. These results demonstrate that in vivo the acid-etched and ground dental enamel sur faces are less protected and consequently, unless the tooth is properl y protected, are more susceptible to carious lesions. Therefore ground or accidentally etched enamel should be protected.