Many-year studies on aerosols as an infection vector, despite their wide range, ignored dental aerosol. All procedures performed with the use of dental unit handpieces cause the formation of aerosol and splatter which are commonly contaminated with bacteria, viruses, fungi, often also with blood. Aerosols are liquid and solid particles, 50 mum or less in diameter, suspended in air. Splatter is usually described as a mixture of air, water and/or solid substances; water droplets in splatter are from 50 mum to several millimetres in diameter and are visible to the naked eye. The most intensive aerosol and splatter emission occurs during the work of an ultrasonic scaler tip and a bur on a high-speed handpiece. Air-water aerosol produced during dental treatment procedures emerges from a patient's mouth and mixes with the surrounding air, thus influencing its composition. Because air contained in this space is the air breathed by both dentist and patient, its composition is extremely important as a potential threat to the dentist's health. According to the author, insufficient awareness of health risk, working habits, and economic factors are the reasons why dentists do not apply the available and recommended methods of protection against the influence of bioaerosol and splatter. Behaviour protecting a dentist and an assistant from the threat resulting from the influence of dental aerosol cannot be limited to isolated actions. The author, on the basis of the literature and own research, characterizes bioaerosol and splatter in a dental surgery and reviews a full range of protective measures against these risk factors.