Determination of resin cure using infrared analysis without an internal standard.
OBJECTIVE
The purpose of this study was to develop a methodology whereby the monomer conversion of dental restorative resins which contain no functional group acting as an internal standard can be easily determined using infrared spectroscopy.


METHODS
Calibration solutions of MMA were made from which the quantification of weight percent methacrylate groups (CH2 = C(CH3)C = O) (termed WPMG) could be determined using infrared spectroscopy. The extent of resin cure using the WPMG method consisted of calculating the changes in WPMG pre- and post-cure. The extent of cure of a commercial unfilled bonding resin was calculated using infrared methods utilizing the internal aromatic standard, and also by means of WPMG.


RESULTS
WPMG had an identical optical constant for a wide range of monomers: MMA, TEGDMA, EGDMA, HEMA: The extent of monomer conversion using both methods of analysis indicated statistically equivalent results: 75.2 +/- 1.0% using an internal standard, and 76.0 +/- 1.1% using WPMG.


CONCLUSIONS
The methods developed in this study using infrared spectroscopic methods facilitate the determination of cure of dental resins which do not have functional groups to serve as internal standards.
Rueggeberg
F A
FA
Medical College of Georgia School of Dentistry, Augusta 30912-1260, USA.
D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D008689:Methacrylates / Q000032:analysis* / Q000737:chemistry; D020366:Methylmethacrylate; D008768:Methylmethacrylates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry*; D012044:Regression Analysis; D013055:Spectrophotometry, Infrared
D008689:Methacrylates; D008768:Methylmethacrylates; D011109:Polymethacrylic Acids; C020946:triethylene glycol dimethacrylate; D020366:Methylmethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate; C004919:ethylene dimethacrylate