Gas-liquid chromatographic analysis of amino acids in pellicle formed on tooth surface and plastic film in vivo

Abstract

The amino acid composition of 2-h-old pellicle formed in vivo on tooth enamel and on plastic film (polyvinylchloride/polyvinylacetate) applied on tooth surfaces was studied. For comparison, saliva samples were analysed. On 5 consecutive mornings, the plastic film was applied on the buccal surfaces of 12 teeth in each of 4 subjects. After 2 h, the films were removed and material from the buccal surfaces of the 12 contralateral teeth was scraped off with a curette and pooled with material collected in the same way in the afternoon. A sample of whole unstimulated saliva was collected in the afternoon. After acid hydrolysis, N-trifluoro-acetyl- n-butyl derivatives of the amino acids were analysed by gas-liquid chromatography. The amount of protein in the pellicle samples (20–300 μg in the hydrolysates) allowed analysis to be performed well above the detection limit of the method. Thirteen amino acids were separated; the predominant ones in the film samples were in order: glutamic acid, glycine, aspartic acid, leucine and serine, and in the tooth samples: glutamic acid, glycine, serine, aspartic acid, leucine. Between film and tooth samples, statistically significant differences were observed in the amounts of glycine, isoleucine, serine and lysine. In the saliva samples, the predominant amino acids were in order: glutamic acid, glycine, proline, aspartic acid and leucine. Tyrosine and phenylalanine were in small amounts in all samples.