The DIAGNOdent pen in the image above uses ultraviolet light. Which spectrum would reveal to the dentist the presence of a cavity?

To identify the presence of a cavity using a DIAGNOdent pen that employs ultraviolet (UV) light, we need to consider the spectrum of light that can effectively illuminate dental materials and target carious tissue.

1. Ultraviolet Spectrum: The ultraviolet spectrum is divided into different ranges:

   • UVA (320-400 nm)
   • UVB (280-320 nm)
   • UVC (100-280 nm)

2. Detection of Cavities: Cavities can be identified because they will fluoresce or react differently under UV light compared to healthy tooth structure.

3. Specific Wavelength: Research suggests that UV light, particularly in the range of UVA (365 nm), is most effective for detecting dental caries due to the fluorescence properties of dental tissues and the biochemical changes that occur in carious lesions.

Final Answer

The UVA spectrum, specifically around 365 nm, would reveal the presence of a cavity to the dentist when using the DIAGNOdent pen.