Dental operating lights and illumination of the dental surgery.

The requirements laid down in national and international standards and draft standards provide helpful guidelines for optimum illumination (Fig. 1, Table I). General room illumination with 500 lx and illumination of the working area with 1000 lx are best achieved with a larger number of fluorescent lamps on the ceiling above and in front of the dental chair. Daylight white lamps with good colour rendering (e.g. Osram colour 19 or Philips colour 47) are a good combination with changing daylight and the colour of light of the operating light. The colour of external skin, mucous membrane and teeth appears natural. The eight surgical lights examined differ in quality (Figs. 2-9). The maximum illuminance is between 9000 and 21 000 lx and is thus sufficiently high. The evenness of light distribution within an ellipse 9 cm and 18 cm in diameter is between 1 : 4 and 1 : 15 (Figs. 10 and 11). Illuminance can be adjusted to the work in hand by means of controls. If the patient looks into the operating lights (Figs. 2c and 9c), maximum luminances of 5 cd/cm2-20 cd/cm2 occur 8 cm above the illuminance maximum in six operating lights. Luminances of more than 20 cd/cm2 cause squinting and running eyes. A light fitting with more than 200 cd/cm2 should not be used. A sharp fall in illuminance (distinct light/dark threshold) and low luminances to the patient's eyes can be achieved with very directed light. Very directed light leads to very heavy shadows. Similarly, less specifically directed light leads to softer shadows so that objects in the oral cavity can be discerned easily, but the patient is no longer dazzled. The following operating lights can be recommended if the patient is to suffer as little glare as possible: Den-Tel-Ez Daray, and Belmont Type 040, Faro Sunlight S 70, Ritter Super Starlite; as well as: Chirana Fax, Siemens Sirolux. The following can be recommended for good illumination of the oral cavity: Belmont Type 040, Chirana Fax, Emda Top Spot, Faro Sunlight S 70, Pelton and Crane Light Fantastic Plus, Ritter Super Starlite, Siemens Sirolux. The colour temperature, heat radiation, easy handling, stability and price are also important for qualitative assessment.