INSTRUMENTS IN OPERATIVE DENTISTRY
CONTENTS INTRODUCTION HISTORY CLASSIFICATION INSTRUMENTS FOR TOOTH STRUCTURE REMOVAL o HAND INSTRUMENTS NON-CUTTING INSTRUMENTS CUTTING INSTRUMENTS o SHARPENING OF HAND INSTRUMENTS o POWERED CUTTING EQUIPMENT o ROTARY INSTRUMENTS INSTRUMENTS FOR RESTORING PROCEDURES
INTRODUCTION Operative dentistry is an art and science, which requires a high degree of precision for a successful outcome. The armamentarium of operative dentistry has grown tremendously over the years resulting in a highly successful and predictable outcome.
The need for a distinctive instrument in every single step of each treatment procedure is responsible for the huge armamentarium we have today.
The judicious usage of hand cutting instruments along with
mechanical one’s is the key for a successful conservative therapy.
The aim of this compilation is to provide complete information regarding design principles, concepts and operating procedures of various instruments both hand cutting and mechanized used in operative dentistry.
HISTORY OF DENTAL INSTRUMENTS Prehistoric man used sharp pieces of flint for trephineing holes in bones. Hippocrates in 350 B.C. described a drill driven by a cord wound around d a shaft. Celsus (25 B.C. –50 A.D) described two kinds of drillers or “Terebra”. One with a guard to prevent it from sinking deep into the tissues and the other one was similar to a carpenter’s drill. In 2A.D. Cladius Galenius a celebrated physician reports of Archigenes an eminent surgeon of Asia minor and practicing in Rome successfully treated tooth ache by opening the tooth with a trephine.
Galen (130 –200 A.D) modified Celsus’s “Terbra” and called it “Terebraabatista” or “Modiolus”. Lubrication was done with olive oil or milk or by dipping in cold water.
Abulcasis (936 – 1013 A.D) described a boring instrument “Incisura”.
Perre Fauchard “Father of Dentistry” in his book “The
Chirurgien Dentiste “ in 1728 described the first dental rotary instrument of modern times. It was known as the “Bow Drill” could be rotated at 300rpm and was later on modified into the “Scranton’s drill” which could cut by rotating in either direction.
In 1831 dental chair was introduced. In 1838 John Levis made a hand held drill. Dr. West Cott in 1846 used “Fingerings” with drills. Taft called them “Bur Drills”. ‘Chevalier drill stock” was hand powered like an egg-beater.
Tomes in 1859 described three types of burs.
1. Rose head: a short shank bur inserted in a crutch rotated between thumb and index finger supported at the base of the thumb. 2. Long hand bur: teeth are cut for same distance along the shaft and it is mounted in a handle. 3. Long steel shaft with too cutting blades.
Charles Merry in 1862 used a “Drill Stock” which had a flexible cable drive. George Fellows Harrington in 1865 used “Clock work drill” or “Harrington’s Erado” which is the first motor driven drill. At first burs were hand cut and ground and were expensive. America in 1860s began mass production of burs from carbon steel. The earliest burs had limited lateral and end cutting action. The diameter varied form 1/32” to 1/5”. These were particularly used for small and medium sized varieties. These carbon steel burs were called “Small milling cutters”.
In 1871 Morison’s foot engine was introduced. Rotation of cutting instrument was made possible by a long belt running over a series of pulleys to the back of a straight hand piece. When the angle hand piece was needed it would be attached to the shaft of the straight hand piece. A speed of 700 rpm was obtained.
In 1873 Coxeter used an electric engine with a speed of 1000 rpm. This is the predecessor of the modern micromotor. This was held in hand and connected to a coil. The motor was open and the spindle of the motor was connected with the hand piece.
In 1874 the electric motor hand piece was invented by S.S white and later he also pioneered the invention of various carbon steel burs and hand pieces.
In 1883 rotary power from an electric engine was transferred to the straight hand piece by a belt that ran over a series of pulleys and a threepiece extension cord arm. A variable rheostat was used as a foot control. Rotary cutting instruments were inserted into the chucking mechanism at the front of the handpiece. The desired angle hand piece is attached to the front of the straight hand piece and a shaft and gears inside the angle section produce rotation of the working instrument.
In 1891 Edward G. Acheson an American invented and produced carborundum and carborundum tools were introduced. In 1901 hand piece with forward (clockwise) and reverse (anticlockwise) direction of rotation and burs for each type movement were brought into use.
In 1910 Emile Huet a Belgian perfected an electric engine to give a speed of 10,000 rpm. In 1935 diamond abrasives were introduced and W.H Drendel introduced the process of galvanized bonding of diamond powder to copper blanks and used at a speed of 5,000 rpm. In 1947 Tungsten carbide was introduced and S.S White in 1948 made tungsten carbide burs which were used at a speed of 12,000 rpm. In 1949 Walsh and Symons used diamond points at a speed of 70,000 rpm.
In 1950 ball bearings were used in contra angel handpieces. In 1951 air abrasive technique was introduced. In 1953 Nelson produced a Hydraulic driven turbine angle handpiece of speed, 60,000 rpm. In 1955 Page-chayes introduced first belt-driven angle handpiece to operate successfully at speeds over 100,000 rpm.
In 1955 Turbo-jet was designed as a compact mobile unit that required no outside plumbing or air connections.
Only a source of
electricity was need. A sound proof cabinet contained a motor, water pump, water reservoirs and necessary plumbing for water circulation. Water was conveyed to and from the hand piece by co-axial type plastic tubing. The small inner tube carried water under high pressure to rotate a turbine in the handpiece head and the larger outer tube returned the water to the reservoir for re circulation.
In 1960 ultrasonics were used for hard tooth structure removal. In 1961 air turbine straight handpiece was introduced. In 1962 air turbine angle handpiece with air bearings were introduced. Most modern angled handpieces also include fireoptic lighting of the cutting site.
INSTRUMENTS FOR TOOTH STRUCTURE REMOVAL HAND INSTRUMENTS The term instrument refers to a tool device or on implement used or a specific purpose or type of work.
HAND INSTRUMENTS NON-CUTTING INSTRUMENTS Examining instruments Restoring instruments CUTTING INSTRUMENTS For tooth structure removal For trimming restoration