Correlation of amide I and III components in the human dentine infrared spectrum

This study investigates the correlation between Amide I and III components in dentine's infrared spectrum, focusing on structural changes due to acidic conditioning and adhesive treatments. Human dentine specimens (n=40) were treated with phosphoric acid, phytic acid, and two self-etching adhesives (G-Premio Bond and Adhese Universal), then analyzed using ATR-FTIR spectroscopy. Deconvolution of Amide I and III peaks quantified changes in secondary structures, including α-helices, β-sheets, and β-turns. Results showed strong positive correlations between specific Amide I and III components. The collagen triple helix remained stable after treatment, indicating its potential for normalizing Amide III components. Amide I, however, remains preferred for calculating the mineral-to-matrix ratio due to its higher intensity. The study highlights that Amide III analysis may be more accurate for monitoring structural changes in dentine collagen, avoiding errors from overlapping water vibrations with Amide I.