High-Contrast Reflectance Imaging of Composite Restorations Color-Matched to Tooth Structure at 1000-2300-nm

A major advantage of composite restoration materials is that they can be color matched to the tooth. However, this presents a challenge when composites fail and they need to be replaced. Dentists typically spend more time repairing and replacing composites than placing new restorations. We have shown in previous studies that high-contrast images of composite can be acquired in occlusal transmission mode at near-IR wavelengths coincident with higher water absorption. The purpose of this study was to determine if similar high-contrast images can be acquired in reflectance mode at longer wavelengths where water absorption is even higher. Extracted human teeth with existing composite restoration (n=14) were imaged at wavelengths from 900-2300 using an extended range InGaAs camera. Our results indicate that NIR wavelengths longer than 1400-nm coincident with higher water absorption yield the highest contrast between dental composites and tooth structure in reflectance.