A
dental drill (or
dentist's drill) is a small, high-speed
drillA drill is a tool with a rotating drill bit used for drilling holes in various materials. The drill bit is gripped by a chuck at one end of the drill and rotated while pressed against the target material...
used in
dentistryDentistry is the known evaluation, diagnosis, prevention, and treatment of diseases, disorders and conditions of the soft and hard tissues of the jaw , the oral cavity, maxillofacial area and the adjacent and associated structures and their impact on the human body. Dentistry is a part of stomatology...
to remove decayed tooth material prior to the insertion of a dental filling. Dental drills are used in the treatment of
dental cariesDental caries, also known as tooth decay or cavity, is a disease wherein bacterial processes damage hard tooth structure . These tissues progressively break down, producing dental cavities . Two groups of bacteria are responsible for initiating caries: Streptococcus mutans and Lactobacilli...
. The term "dental drill" is considered the more colloquial form of the term "
dental handpiece," although it can also be construed as to include the power source for one or more handpieces, a "
dental engineA dental engine is a large chair-side appliance found in a dentist's office. At minimum, a dental engine serves as a source of mechanical or pneumatic power for one or more handpieces; typically, it will also include a small faucet and a spit-sink, which the patient can use for rinsing, as well as...
." "Handpiece" and "engine" are more generic and euphemistic terms for generic dental tools.
Modern dental drills can rotate at up to 500,000
rpmRevolutions per minute is a unit of frequency of rotation: the number of full rotations completed in one minute around a fixed axis...
, and generally use hard metal
alloyAn alloy is a partial or complete solid solution of one or more elements in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal history...
bitsDrill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes....
(actually small rotary
filesA file is a hand tool used to shape material by cutting. A file typically takes the form of a hardened steel bar, mostly covered with a series of sharp, parallel ridges or teeth...
) known as 'burs'. Dental burs come in a great variety of shapes designed for specific applications. They are often made of
steelSteel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten...
with a
tungsten carbideTungsten carbide, WC is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...
coating, or of tungsten carbide entirely. The bur may also have a
diamondIn mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is the second most stable form of carbon, after graphite; however, the conversion rate from diamond to graphite is...
coating.
Dental drills, which have a distinctive, shrill sound, are often a prominent factor in many people's fear of dentistry (dentophobia).
History
The
Indus Valley CivilizationThe Indus Valley Civilization was a Bronze Age civilization which centred mostly in the western part of the Indian Subcontinent and flourished around the Indus river basin....
has yielded evidence of dentistry being practiced as far back as 7000 BCE. This earliest form of dentistry involved curing tooth related disorders with
bow drillThe bow drill or is an ancient tool. While it was usually used to make fire, it was also used for primitive woodworking and dentistry. It consists of a bearing block or handhold, a spindle or drill, a hearth or fireboard, and a simple bow...
s operated, perhaps, by skilled bead craftsmen. The reconstruction of this ancient form of dentistry showed that the methods used were reliable and effective. Cavities of 3.5 mm depth with concentric groovings indicate use of a drill tool. The age of the teeth has been estimated at 9000 years. In later times, mechanical hand drills were used. Like most hand drills, they were quite slow, with speeds of up to 15
rpmRevolutions per minute is a unit of frequency of rotation: the number of full rotations completed in one minute around a fixed axis...
. In 1864,
BritishThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
dentist George Fellows Harrington invented a
clockworkA clockwork is the inner workings of either a mechanical clock or a device that operates in a similar fashion. Specifically, the term refers to a mechanical device utilizing a complex series of gears.- Overview :...
dental drill named
Erado. The device was much faster than earlier drills, but also very noisy. In 1868,
AmericanThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
dentist George F. Green came up with a pneumatic dental drill powered with
pedalThe word pedal comes from the Latin and relates to the foot.A pedal is a lever activated by one's foot. Examples include:* Automobile pedal* Bicycle pedal...
-operated
bellowsA bellows is a device for delivering pressurized air in a controlled quantity to a controlled location. Basically, a bellows is a deformable container which has an outlet nozzle. When the volume of the bellows is decreased, the air escapes through the outlet...
. James B. Morrison devised a pedal-powered burr drill in 1871.
The first electric dental drill was patented in 1875 by Dr. Green, a development that revolutionized dentistry. By 1914, electric dental drills could reach speeds of up to 3000
rpmRevolutions per minute is a unit of frequency of rotation: the number of full rotations completed in one minute around a fixed axis...
. A second wave of rapid development occurred in the 1950s and 60s, including the development of the air
turbineA turbine is a rotary engine that extracts energy from a fluid or air flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum, with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they...
drill.
The modern incarnation of the dental drill is the air turbine handpiece, developed by John Patrick Walsh (later knighted) and members of the staff of the Dominion Physical Laboratory (DPL) Wellington , New Zealand. The first official application for a provisional patent for the handpiece was granted in October 1949. This handpiece was driven by compressed air. The final model is held by the Commonwealth Inventions development Board in Canada. The New Zealand patent number is No/104611. The patent was granted in November to John Patrick Walsh who conceived the idea of the contra angle air-turbine handpiece after he had used a small commercial-type air grinder as a straight handpiece. Dr. John Borden developed it in America and it was first commercially manufactured and distributed by the DENTSPLY Company as the Borden Airotor in 1957.
Current iterations can operate at up to 800,000 rpm, however, most common is a 400,000 rpm "high speed" handpiece for precision work complemented with a "low speed" handpiece operating at a speed that is dictated by a micromotor which creates the momentum (max up to 40,000 rpm) for applications requiring higher torque than a high-speed handpiece can deliver.
Dental bur
A
dental bur is a type of
drill bitDrill bits are cutting tools used to create cylindrical holes. Bits are held in a tool called a drill, which rotates them and provides torque and axial force to create the hole. Specialized bits are also available for non-cylindrical-shaped holes....
used in a
handpieceA dental drill is a small, high-speed drill used in dentistry to remove decayed tooth material prior to the insertion of a dental filling. Dental drills are used in the treatment of dental caries...
(commonly called a dental drill). The burs are usually made of
tungsten carbideTungsten carbide, WC is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...
or
diamondIn mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is the second most stable form of carbon, after graphite; however, the conversion rate from diamond to graphite is...
. The three parts to a bur are the head, the neck, and the shank.
The head of the bur contains the
bladeA blade is the flat part of a tool, weapon, or machine that normally has a cutting edge and/or pointed end typically made of a flaking stone, such as flint, or metal, most recently steel...
s which produce the cutting action. These blades may be positioned at different degrees of
angleIn geometry and trigonometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle...
s in order to change the property of the bur. More obtuse angles will produce a negative rake angle which increases the
strengthPhysical strength is the ability of a person to exert force on physical objects using muscles. Increasing physical strength is the goal of strength training.-Overview:...
and
longevityThe word "longevity" is sometimes used as a synonym for "life expectancy" in demography. However, this is not the most popular or accepted definition...
of the bur. More acute angles will produce a positive rake angle which has a sharper blade, but which dulls more quickly.
There are various shapes of burs, which helps to determine a selection of a bur in a given situation. Shapes include a round, inverted cone, straight fissure, tapered fissure, and pear-shaped burs. Additional cuts across the blades of burs were added to increase cutting
efficiency- In science and technology :* Efficiency , a count of desirability of an estimator* Algorithmic efficiency, optimizing the speed and memory requirements of a computer program* Efficiency factor, in data communications- In economics :...
, but their benefit has been minimized with the advent of high-speed handpieces. These extra cuts are called crosscuts.
Due to the wide array of different burs, numbering systems to categorize burs are used and include a US numbering system and a numbering system used by the
International Organisation for StandardisationThe International Organization for Standardization , widely known as ISO , is an international-standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promulgates worldwide proprietary industrial and commercial...
(ISO).
Alternatives
Starting in the 1990s, a number of alternatives to conventional rotary dental drills have been developed. These include
laser ablationLaser ablation is the process of removing material from a solid surface by irradiating it with a laser beam. At low laser flux, the material is heated by the absorbed laser energy and evaporates or sublimates. At high laser flux, the material is typically converted to a plasma...
systems and air
abrasionIn dermatology, an abrasion is a wound caused by superficial damage to the skin, no deeper than the epidermis. It is less severe than a laceration, and bleeding, if present, is minimal. Mild abrasions, also known as grazes or scrapes, do not scar or bleed, but deep abrasions may lead to the...
devices (essentially miniature sand blasters).
Other uses
Dental drills and drill bits are commonly used by jewellers and hobbyists for high-precision drilling work.
External links
- "Dental More Gentle with Painless 'Drillings' and Matching Fillings", Food and Drug Administration
The Food and Drug Administration is a Government agency of the United States Department of Health and Human Services and is responsible for regulating and supervising the safety of foods, tobacco products, dietary supplements, Medication drugs, vaccines, Biopharmaceutical, blood transfusion,...
(FDA) Consumer magazine, May-June 1999
- "'Robotic' dental drill to be tested on humans", New Scientist
New Scientist is a weekly international science magazine and website covering recent developments in science and technology for a general English-speaking audience. Founded in 1956, it is published by Reed Business Information Ltd, a subsidiary of Reed Elsevier. New Scientist has maintained a...
, 20 April 2005
- "Dental Technology and Research", Canadian Dental Association Web Site - (PDF file)
- "History of Dentistry", American Dental Association Web Site