High-speed handpiece - Can cut at speeds of up to 180,000 rpm - Classified as air turbine or speed-increasing - Air turbine handpieces commonly referred to as high-speeds - Have a chuck or collet for holding a cutter called a burr - Used in clinical context for various dental procedures

Mechanisms - Powered by compressed air between 35 and 61 pounds per square inch - Turbine rotates a Pelton wheel in the head of the handpiece - Bearing housing holds the burr firmly and centrally within the instrument - Small ball bearings allow the burr to rotate smoothly along a central axis - Failure to run centrally can cause clinical defects and decreased control

Cooling - High-speed friction generates heat within the burr - High-speed handpieces have an excellent water-cooling system - Standard cooling water flow rate is 50 ml/min - Cooling water is provided through 3 to 5 spray hole jets - Effective cooling is essential to prevent overheating

Illumination - Modern handpieces have a light in close proximity to the burr - Light is directed at the cutting surface to assist with vision - Older handpieces used halogen lamps and fiber-optic rods - Halogen bulbs decay over time and are costly to repair - LED technologies are now used for longer operating life and better light production

Speed-increasing handpiece - Electric motors cannot turn as fast as air turbines - Gears are needed to increase the speed of an electric motor - Also known as micromotor - Power is provided by the micromotor and internal gearings - Allows cutting speeds over 180,000 rpm

Evolution of Dental Drills: - Ancient dentistry involved the use of bow drills operated by skilled craftsmen. - Mechanical hand drills were introduced in later times, but they were slow. - In 1864, British dentist George Fellows Harrington invented the clockwork dental drill named Erado, which was faster but noisy. - In 1868, American dentist George F. Green developed a pedal-operated pneumatic dental drill. - James B. Morrison created a pedal-powered burr drill in 1871. - The first electric dental drill was patented in 1875 by George F. Green, revolutionizing dentistry. - By 1914, electric dental drills could reach speeds of up to 3,000 rpm. - In the 1950s and 60s, the development of the air turbine drill brought further advancements. - The modern incarnation of the dental drill is the air turbine contra-angle handpiece, allowing access to less accessible areas of the mouth. - Current iterations can operate at speeds up to 800,000 rpm.

Alternatives to Conventional Dental Drills: - Starting in the 1990s, alternatives to rotary dental drills have been developed. - Dental laser systems have been introduced as an alternative tool for dental work. - Air abrasion devices combine small abrasive particles with pressurised air for precise dental treatments. - Ozone and silver diamine fluoride (SDF) have also been used as alternative dental treatments. - These alternatives offer different benefits and applications in restorative dentistry.