How do Dental Drills Work

Powered by electric or air-driven motors, modern dental drills have come a long way since the early days of medieval dentistry. As well as a motor, the other main components of today’s dental drills are an ergonomic handpiece, gears and a tungsten drill bit, also known as a bur.

Located inside the drill’s handpiece is a series of drive shafts and gears that transmit rotary motion from the power supply to the tungsten drill bit at the head end.

Electrically motorized drills can rotate at about 30,000rpm. For a turbine-powered drill, a compressor converts pressurized air into mechanical energy that rotates the bur at over 300,000rpm. This generates a huge amount of heat, so high-speed devices are also connected to a cooling water supply.

New technologies in development – including laser and air-abrasion drills – are hoping to improve the experience of going to the dentist by providing drills that remove decay without generating the heat, noise and vibrations associated with their predecessors. The laser drill achieves this by combining the high-speed pulsed light from a laser with an atomized spray of water droplets to generate hydrokinetic energy. Air-abrasion drills, meanwhile, work like a mini sandblaster that fires a stream of abrasive powder (such as silica or ammonium oxide) at the tooth to blast the decay away.

Why do we get cavities?

The bacteria that break down food on your teeth leave behind a by-product called plaque. Bacteria love plaque and they love to multiply. So when plaque builds up on a tooth the bacteria stick to it and cultivate a colony that, if ignored, can mineralize to become hard-to-remove tartar. The bacteria can also secrete an acid that causes tiny holes to develop in a tooth’s enamel. More bacteria fill these holes and start to erode the soft dentin below. To prevent the many oral diseases that can arise due to plaque, dentists must remove all the plaque that creates this home for germs. The only way to ensure all the plaque has been removed is to wear it away with a drill. The sterile hole is then filled with a material like amalgam.

Dental drill parts

Handpiece – The motor, gears and drive shaft are contained within the handpiece, which can be made of either plastic or titanium.

Turbine type – The rotary system in an air-powered turbine drill features an impeller (rotor) to catch air from the compressor. The rotor is mounted on a spindle that rotates at high speed.

Drive shaft – Attached to the rotating drive shaft are several gears. These toothed wheels smoothly transmit rotary motion along the length of the drill.

LED bulbs – The introduction of fibre optics and, more recently, LED light bulbs mounted in the head means the mouth is well illuminated so the dentist can get the best view of what’s going on.

Drill bit – Burs must be hard enough to wear away robust tooth enamel and so they are often made of materials like tungsten carbide and some are even tipped with diamond – two of the hardest of all substances.