Repeatability of a specially designed intraoral colorimeter

Area of Science:

• Dental Materials Science
• Colorimetry
• Prosthodontics

Background:

• Accurate color measurement is crucial for dental prosthetics.
• Existing colorimeters may require modification for intraoral use.
• Assessing the long-term repeatability of intraoral colorimeters is essential for clinical reliability.

Purpose of the Study:

• To evaluate the repeatability of a modified Minolta CS-100 colorimeter with a DP-101 data processor for intraoral color measurements.
• To assess color stability of porcelain and acrylic resin denture teeth.
• To determine the clinical applicability of the device for shade matching.

Main Methods:

• A modified Minolta CS-100 colorimeter was used for intraoral measurements.
• Porcelain and acrylic resin denture teeth (n=5 each) were tested.
• L*a*b* color readings were taken on the same day, day 3, and day 8, with and without recalibration.

Main Results:

• Same-day repeatability showed delta E values < 0.4 for most samples.
• Repeatability decreased significantly by day 3 (delta E < 0.4 in only 2/10 samples).
• Day 8 results after recalibration showed delta E values > 0.4 in all samples (0.57–2.75), with in vivo testing yielding delta E values from 1.1 to 32.1.

Conclusions:

• The modified intraoral colorimeter demonstrated poor long-term repeatability for denture tooth color measurements.
• Recalibration did not consistently restore acceptable color measurement accuracy.
• The findings suggest limitations in using this device for reliable clinical shade matching of dental prosthetics over time.