Disclosed is a lighting device (P, P, Q, Q) for use with a dental or medical instrument having a tool (10) in the distal part of the instrument for treatment of a site. The lighting device (P, P, Q, Q) includes a plurality of LEDs (7) and an LED holder (5, 5, 50, 50) encasing the plurality of LEDs (7) and capable of being mounted on a distal part of the instrument. The LEDs (7) are arranged so as to illuminate the site substantially without casting a shadow on the site in treatment when the LED holder (5, 5, 50, 50) is mounted on the instrument. Also disclosed is a dental or medical instrument including a tool (10) in the distal part of the instrument for treatment of a site and a lighting device (P, P, Q, Q). The lighting device (P, P, Q, Q) further includes a plurality of LEDs (7) and an LED holder (5, 5, 50, 50) encasing the LEDs (7) and provided in the distal part of the instrument. The LEDs (7) are arranged so as to illuminate the site substantially without casting a shadow on the site in treatment.
