# Dental drill > Spinning a small cutter fast enough to carve into a tooth - Date: c. 5,000 BCE - Era: Prehistory - Domain: [Medicine & Hygiene](https://lastcodex.org/en/domains/medicine/) - Rebuild stage: III (Crafts & cities) - Difficulty: 3/5 - URL: https://lastcodex.org/en/inventions/dental-drill/ A dental drill spins a small cutter, the bur, fast enough to cut away enamel and dentine. The oldest drilled teeth, holed with flint points turned by a bow, come from Mehrgarh in Pakistan, dated to between about 5200 and 4700 BCE by tooth enamel, where earlier estimates said 7000 to 5500 BCE. Foot treadles drove the drill from 1871, and air turbines have spun it at hundreds of thousands of turns a minute since 1957. ![Dental drill · Spinning a small cutter fast enough to carve into a tooth](https://lastcodex.org/_astro/plate.alHN0hw9_Zjbz2U.webp) ## Legend 1. Treadle worked by the foot 2. Connecting rod and crank 3. Driving wheel 4. Cord over a pulley of the jointed arm 5. Spindle turning inside the handpiece 6. Steel bur held in the chuck ## What it is A dental drill is a rotating tool that cuts into a tooth. Dentists use it to remove decay before a filling, to shape a tooth that will carry a crown and to open the inside of a tooth for root treatment. The part that cuts is the bur, a small head of steel, tungsten carbide or diamond grit on a thin shank. The bur is held in a handpiece, which the dentist guides with the fingers like a pen. The bur has always been small. What turns it has changed many times: a bow, the fingers or a hand crank, a clockwork spring, a foot treadle, an electric motor and, since the late 1950s, a tiny turbine driven by compressed air. ## How it works ![Three steel dental burs standing side by side in a leather-covered block, a round head, an inverted cone and a cylinder with spiral blades, each on a plain cylindrical shank](https://lastcodex.org/_astro/v1.B36cA8ox_1W5Yg8.webp) _Burs come in many head shapes. The blades scrape off chips of tooth as the head spins._ A bur works like a tiny milling cutter. Its blades, or the diamond grit bonded to its head, scrape off chips of enamel and dentine as it turns. Enamel is very hard, and a bur that turns slowly must be pressed hard and shakes the tooth. Speed was therefore the main aim of every new drive. The St. Louis dentist James B. Morrison claimed about 2,000 turns a minute for his foot engine of 1871, where earlier hand drills managed about 15. Belt-driven handpieces ran at about 2,000 turns a minute in 1938 and 6,500 in 1950. In a treadle engine, the foot rocks a treadle up and down. A connecting rod turns a crank on a heavy driving wheel, and a cord carries the rotation from the groove of that wheel to small pulleys at the joints of a hinged arm, then to a pulley on the back of the handpiece. Inside the handpiece a steel spindle turns with that pulley and holds the bur at its tip, while the outer tube stays still in the dentist's hand. Morrison's patent added springs at the joints to keep the cord tight as the arm moves. Other engines sent the motion through a flexible shaft, a coil of steel wire turning inside a sheath, which the Scottish engineer James Nasmyth had described in 1829. ![Cutaway of the head of an air-turbine handpiece, with an air channel blowing onto a small bladed rotor held between two ball bearings, the bur gripped at the centre of the rotor and a fine water nozzle aimed at its tip](https://lastcodex.org/_astro/v2.C_Oh2KRO_29eJQK.webp) _In an air turbine the bur sits at the centre of a rotor that the air jet spins._ An air turbine has no belt or shaft at all. Compressed air flows down the handpiece and strikes a small bladed rotor in its head, and the bur is gripped at the centre of that rotor. Running free, a modern turbine turns at 330,000 to 400,000 turns a minute, according to the maker W&H, and slows to about half that while cutting, because it has little torque. Electric micromotors turn more slowly, up to about 40,000 turns a minute, but a handpiece with internal gears multiplies that speed by five at the bur and keeps it steady under load. At such speeds friction heats the tooth, so modern handpieces spray water onto the bur through small nozzles. ## How to do it This exercise drills a plaster model tooth with a bow drill, to see how a spinning point cuts something hard. It has nothing to do with treating teeth: never use a drill, a file or any tool on a real tooth, on a person or on an animal. Mix plaster of Paris with water, pour it into a small paper cup and let it harden for a day. Peel off the cup: this block of plaster is your tooth. For the drill, take a straight hardwood dowel about 25 cm long and 10 mm thick. Drill a small hole in one end and glue in a 3 mm drill bit, or a hardened steel nail with its point filed sharp. Round off the other end so that it turns freely in a shallow hole cut in a small block of wood, the handhold. Rub soap or candle wax into that hole. Make the bow from a slightly springy stick about 60 cm long, with a cord tied to both ends and left slack enough to wrap once round the dowel. Clamp the plaster block in a vice or to a bench. Wrap the cord once round the dowel, set the bit on the plaster, press lightly on the handhold and move the bow back and forth in long strokes. The dowel spins one way, then the other, and the bit bites into the plaster. Look into the hole with a magnifying glass: its walls carry fine circular ridges, like those seen inside the holes at Mehrgarh. ## History and evolution ![A Neolithic bow drill lying on bare earth among flint chips, a wooden rod with a small flint point bound to its tip, a curved bow whose cord wraps once round the rod and a stone cap at the other end, beside a human molar with a small round hole in its chewing surface](https://lastcodex.org/_astro/v3.DN8__WCV_Z2hIFwE.webp) _A flint-tipped bow drill of the kind used at Mehrgarh, with a drilled molar._ The oldest drilled teeth come from a Neolithic cemetery at Mehrgarh, in present-day Pakistan. Its excavators dated it to between about 7000 and 5500 BCE, but radiocarbon dates on the tooth enamel of 23 of its dead, published in 2025 by Benjamin Mutin and colleagues, place it between about 5200 and 4700 BCE. In 2006 Andrea Coppa, Roberto Macchiarelli and their colleagues described eleven molars from nine adults, each with a small round hole 1.3 to 3.2 mm wide and up to 3.5 mm deep. Fine concentric ridges on the walls of the holes point to a rotating tool. The edges had been worn smooth by chewing, so the drilling was done on living people, and four of the teeth showed decay next to the hole. The same villagers drilled beads of shell and turquoise with flint points fixed to wooden rods and spun with a bow. With such a drill, the team made a similar hole in human enamel in less than a minute. No drilled teeth were found in a later cemetery at the site. For thousands of years afterwards, decay was mostly scraped out with hand instruments or with small drills turned by hand. In 1790 John Greenwood, one of George Washington's dentists, built a foot-driven drill from a spinning wheel. In 1858 the St. Louis dentist Charles Merry made a hand-turned drill that used Nasmyth's flexible shaft. In 1864 the English dentist George Fellows Harrington brought out the Erado, a clockwork drill that ran for about two minutes on one winding. It was noisy and awkward, and the treadle soon replaced it. Morrison's treadle engine, patented on 7 February 1871 and first sold the following year, was the first foot-treadle dental engine made for sale, and dentists across Europe and America took it up. George F. Green built an electric dental engine in the same years, but few surgeries had electricity and it did not catch on. In the twentieth century electric motors replaced the foot, but the handpiece was still driven by a belt over pulleys. Harder burs made of tungsten carbide or coated with diamond appeared in the late 1940s and made higher speeds worthwhile. In New Zealand, John Patrick Walsh, dean of the dental school at the University of Otago, developed a handpiece driven by an air turbine with the Dominion Physical Laboratory and patented it in 1949. In the United States, John Borden's Airotor, introduced in 1957, became the first air-turbine handpiece to succeed on the market, running free at up to 250,000 turns a minute. Dentists today use air turbines and electric micromotors side by side, and local [anaesthesia](/en/inventions/anaesthesia/) spares the patient the pain of the cut. ## Key facts - Oldest drilled teeth: Mehrgarh, Pakistan, about 5200 to 4700 BCE (earlier estimate 7000 to 5500 BCE) - Flint bow drill, modern test: A hole in human enamel in under a minute - Morrison's treadle engine: Patented in 1871, about 2,000 turns a minute claimed - Borden Airotor air turbine: 1957, up to 250,000 turns a minute running free ## Requires - [Stone Tools](https://lastcodex.org/en/inventions/stone-tools/): The first cutting edge (3.3 million years ago) - [Rope & Cordage](https://lastcodex.org/en/inventions/rope/): Twisted fibres that hold the world (46,000 years ago) ## Leads to - [Dental prostheses and implants](https://lastcodex.org/en/inventions/dental-prosthetics/): Replacing lost teeth with crowns, bridges and anchors in the bone (c. 630 BCE) ## Sources - [New radiocarbon dates of human tooth enamel reveal a late appearance of farming life in the Indus Valley](https://doi.org/10.1038/s41598-025-92621-5), B. Mutin, A. Zazzo, L. Bondioli, A. Coppa et al., Scientific Reports 15 (2025) - [Neolithic Neophytes](https://archaeology.org/issues/online/digs-discoveries/neolithic-neophytes/), Archaeology magazine, Archaeological Institute of America (2025) - [Early Neolithic tradition of dentistry](https://doi.org/10.1038/440755a), A. Coppa, L. Bondioli, A. Cucina, D. W. Frayer, C. Jarrige, J.-F. Jarrige, G. Quivron, M. Rossi, M. Vidale, R. Macchiarelli, Nature 440 (2006) - [Mystery Drilling: Ancient teeth endured dental procedures](https://www.sciencenews.org/article/mystery-drilling-ancient-teeth-endured-dental-procedures), Science News (2006) - [Dig uncovers ancient roots of dentistry](https://www.nbcnews.com/id/wbna12168308), Associated Press, NBC News (2006) - [US 111,667: Improvement in dental engines (James B. Morrison, 7 February 1871)](https://patents.google.com/patent/US111667), United States Patent Office, via Google Patents - [Dental Drill, 1871](https://exhibits.unmc.edu/whc/item/807), University of Nebraska Medical Center, McGoogan Health Sciences Library - [Dental Treadle Drill](https://collection.sciencemuseumgroup.org.uk/objects/co97430/dental-treadle-drill), Science Museum Group - [Harrington's clockwork dental drill, the Erado](https://collection.sciencemuseumgroup.org.uk/objects/co102130/harringtons-clockwork-dental-drill-the-erado-dental-drill), Science Museum Group - [A Harrington's Improved Clockwork Drill – The Erado, 1864](https://rcosoe-apw.adlibhosting.com/AIS/Details/museum/135), Royal College of Surgeons of England, museum collections - [A dynamic decade: speeding up the handpiece](https://dentalmuseum.pacific.edu/a-dynamic-decade-speeding-up-the-handpiece/), University of the Pacific, Arthur A. Dugoni School of Dentistry - [History of Dentistry](https://www.ada.org/resources/ada-library/dental-history), American Dental Association - [Die Tretbohrmaschine wird 150 Jahre](https://www.zm-online.de/news/detail/die-tretbohrmaschine-wird-150-jahre), zm, Zahnärztliche Mitteilungen - [History of the Faculty of Dentistry](https://www.otago.ac.nz/dentistry/about/history), University of Otago - [Rotary instruments: endurance and power](https://www.wh.com/en_uk/dental-newsroom/reports-and-studies/new-article/00186), W&H Dentalwerk (technical report, 2009) Fact-checked on 2026-10-19. --- The Last Codex · https://lastcodex.org/en/inventions/dental-drill/ · © The Last Codex. Texts, plates and figures: CC BY-NC-ND 4.0.