Related Experiment Video
Updated: Aug 10, 2026

Diffuse Reflectance Infrared Spectroscopic Identification of Dispersant/Particle Bonding Mechanisms in Functional Inks
Published on: May 8, 2015
Determination of double bond conversion in dental resins by near infrared spectroscopy
1Biomaterials Group, Polymers Division, 100 Bureau Drive/Stop 8545, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA. jeff.stansbury@uchsc.edu
Objectives:
This study determined the validity and practicality of near infrared (NIR) spectroscopic techniques for measurement of conversion in dental resins.
Methods:
Conversion measurements by NIR and mid-IR were compared using two techniques: (1) The conversion of 3mm thick photopolymerized Bis-GMA/TEGDMA resin specimens was determined by transmission NIR. Specimens were then ground and reanalyzed in KBr pellet form by mid-IR. (2) As further verification, thin resin films were photocured and analyzed by mid-IR. Multiple thin films were then compressed into a thick pellet for examination by NIR.
Results:
Conversion values obtained by NIR and mid-IR techniques did not differ significantly. A correction for changing specimen thickness due to polymerization shrinkage was applied to NIR conversion measurements since an internal standard reference peak was not employed. Sensitivity of the NIR technique was superior to those based on the mid-IR.
Significance:
The nondestructive analysis of conversion in dental resins by NIR offers advantages of convenience, practical specimen dimensions and precision compared with standard mid-IR analytical procedures. Because glass is virtually transparent in the NIR spectrum, this technique has excellent potential for use with filled dental resins as well.
Related Concept Videos
IR Spectrum Peak Intensity: Amount of IR-Active Bonds
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
Spectroscopy of Carboxylic Acid Derivatives
In the...
UV–Vis Spectroscopy: Woodward–Fieser Rules
Double Resonance Techniques: Overview
Spin decoupling is usually achieved by...

