Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Determination of Double Bond Conversion in Dental Resins by Near Infrared Spectroscopy



J W. Stansbury, Sabine H. Dickens


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 was compared using two techniques: (1)The conversion of 3 mm 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.
Dental Materials Congress
No. 1


conversion, dental materials, methacrylate monomers, near infrared, resins, spectroscopy


Stansbury, J. and Dickens, S. (2001), Determination of Double Bond Conversion in Dental Resins by Near Infrared Spectroscopy, Dental Materials Congress (Accessed April 18, 2024)
Created January 1, 2001, Updated February 17, 2017