2. CONTENTS
● INTRODUCTION
● CLASSIFICATION
● BASIC CHARACTERISTICS OF ROTARY INSTRUMENT
● EVOLUTION OF DENTAL HANDPIECE
● EARLY 20TH CENTURY ADVANCEMENT OF AIRROTORS
● AIROTORS IN THE 1920S
● THE MID 1930S
● AIROTORS IN THE 1940S
● THE NEW ERA OF 1950S
● AIRROTOR OF 1960S
● AIROTORS IN THE 1970S
● IN TO THE 80S
● THE 21st CENTURY AIROTOR
● CONCLUSION
● REFERENCES
3. INTRODUCTION
● The dental handpiece is a sophisticated combination of precision parts
moving in perfect synchronization at extremely high speed.
● It delivers a smooth powerful cut that allows the clinician to remove tooth
structure in an efficient manner with little discomfort in contrast to earlier
days which was done with hand cutting instruments and electric belt driven
instruments with top rotational speeds of 50000 rpm.
● The selection of an appropriate handpiece and appropriate burs is the key
for safe and effective removal of dental hard tissues and caries in an
efficient manner.
4. ● 1. Dental handpieces classified according to driving mechanism-
Gear driven handpiece
Water driven handpiece
Belt driven handpiece
Air driven handpiece
● 2. Depending upon angulations-
Straight
Contra angled
Right angled
CLASSIFICATION OF DENTAL HANDPIECE
5. ● 3. Depending on speed-
Sturdevant classification:
Low or slow speeds (less than 12,000rpm)
Medium or intermediate speeds (12,000 – 20,000rpm)
High or ultra high speeds (more than 200,000 rpm)
Marzouk classification:
Ultra low speed - 300 -3000 rpm
Low or slow speed- 3000 -6000 rpm
Medium or intermediate speed - 20,000 – 45,000rpm
High speed- 45,000 – 1,00,000 rpm
Ultra high speed – more than 1,00,000 rpm
6. ● 4. Based on head design:
Standard
Mini
Torque
● 5. Based on bur holding type:
screw type chuck
airmatic bur changer
ultra push system
● 6. Based on motor:
AIR TURBINE
AIR MOTOR
● 7. Based on colour coding ring:
Blue–no change in speed
Green-speed reduction
Red –speed increase
7. ● 8. Handpieces used in endodontic:
Giromatic handpiece
Reciprocating handpieces
Sonic and ultrasonic handpieces
Torque control gear reduction handpieces
8. BASIC CHARACTERISTICS OF ROTARY INSTRUMENT
● Speed: Speed is defined as the number of revolution per minute (RPM) or
the number of times a rotating instrument, such as a bur, will make a full
turn during a minute,
higher the (RPM)~ faster the speed of handpiece.
● Pressure (P):
- Force (f) the gripping of the hand piece and its positioning and
application to the tooth.
- Area (a) the amount of surface area of the cutting tool in contact
with
the tooth surface during a cutting operation
- Pressure relates as follows
P=F/A
9. ● Heat Production:
Heat is directly proportional to-
Pressure
RPM
Area of tooth in contact with the tool
- Since heat production will cause pulps of teeth to be permanently damaged
If a temperature of 130°Fis reached, heat must be carefully controlled.
- This can be accomplished by using various coolants such as flowing water,
a water air spray, or air.
10. ● Vibration:
-It is not only a major annoying factor for the patient, but it also causes
fatigue for the operator,
excessive wear of instruments
and most importantly, a destructive reaction in the tooth and
supporting tissues vibration is a product of the equipment used
and the speed of rotation
- The deleterious effects of vibration are
Amplitude
Undesirable modulating frequency
11. ● Torque:
- It is the ability of hand piece to withstand lateral pressure on the revolving
tool without decreasing the speed or reducing its cutting efficiency.
- Depends on
Type of bearing used
Amount of energy applied to the handpiece
● MECHANISMS
- According to mechanism of working handpieces are divided into two types-
Air driven
Electric driven
12.
13. EVOLUTION OF DENTAL HANDPIECE
● The Indus Valley civilization has yielded evidence of dentistry being
practiced as far back as 7000 BC.
● This earliest form of dentistry involved curing tooth-related disorders with
bow drills operated, perhaps, by skilled bead craftsmen.
● Mayan people who lived between 2500 BC to 900 AD used round, hard tube
similar in shape to a drinking straw, made in early times of jade and later
of copper, was spun between the hands or in a rope drill, with slurry of
powdered quartz in water as abrasive, cutting a perfectly round hole
through the enamel
14. ● Fauchard designed his own bow drill to cut into the enamel of natural
tooth.
● In the early 1800’s mechanical hand drills were invented, however their
capabilities were minimal and the drills could only reach 15 rotations per
minute.
● One of the first great advancements came in 1864 by British dentist
George Harrington. He invented the clockwork dental drill named the
Erado. It was relatively faster than previous drills but also much noisier.
● The first electric dental drill was patented in 1875 by Dr. George
F.Green.James Beall Morrison, revolutionized the practice of dentistry in
17. ● In 1883, the electric dental engine was linked to the handpiece by a flexible
cable arm. This is the first time cutting was made from a power source
other than human hand and feet.
● In 1887 Dr.C.Edmund Kells patented electric control panel to which a
motor driven handpiece can be attached.
18. ● From, 1875 onwards, the use of foot engine became widespread, but its
demise was foreshadowed by the advent of electric handpiece driving
mechanisms.
● Early electric motors were designed to be attached to foot engines, or
alternatively, as independent entities they could be swung from wall
brackets, be adjustably suspended from the ceiling or, as in the Siemen’s
model of 1897, be hastefully mounted on an ornate cast iron floor stand.
● The modern form of the dental drill is the air turbine handpiece, developed
by John Patrick Walsh.
19. Modern form of the dental drill by
John Patrick Walsh.
Four prototypes of air turbine handpieces.
20. EARLY 20th CENTURY ADVANCEMENT OF AIROTORS
● By 1900, no 7 straight handpiece was initially developed by the SS White
Company.
● It has most ingenious bur chuk-locking mechanism.
● Pulling its outer sheath forward causes the tail of a hinged angular section
to move laterally up a notched incline so that the angle knuckle rammed
forward a bush to tighten the double ended collet chuck on the bur shaft.
● The stud on the knurled portion of the body was to prevent rotation of the
angle head slotting over it.
21. ● During the 1920s, with the establishment of satisfactory production of
models of straight and contra angled handpiece and of their cord arm
drives from ball electric motors operated by variable speed foot
switches,dental equipment manufactures were able to concentrate on the
design of dental units.
● Early integrated assemblies not only supported a ball motor and operating
light, but also provided a cuspidor with saliva ejector, bracat table,
operating light and bunsen burner with hand held instrumentation such as
atomizer, water syringe and air-syringe.
AIROTORS IN THE 1920s
22. Fig- Doriot pattern handpiece
Incorporating the wrist joint
of the cord arm. Angled handpiece
attachments are fitted to the front
end.
23. THE MID 1930s
● A contra angled handpiece of this period would normally be made of
nickel-plated brass with a black ebonite handgrip.
● Its tempered steel central shaft would transmit the drive through angle
and bevel gears from its rear and slip joint dog engagement to the bur
latched into its driving chuck
24. Fig- Contra Angled handpiece of
1930 - 1935
Material- grip, plastic, vulcanite
and handpiece, steel (nickel
plated)
25. AIRROTORS IN THE 1940s
● Throughout the 1940s little change of note occurred in relation to dental
handpiece and their driving mechanisms.
● Some of the drawbacks which still required to overcome were-
-Unit monitored cord arm drive which was the major factor in
compelling the dentist to stand up all day resulting in back pain and
liability to varicose veins.
- Slow speed of rotation of the bur i.e 9000 rev per min.
- The dripping of down blackened oil from sleeve bearings resulting in
slipping.
- Lack of water spray nozzles on handpiece.
26. The NEW ERA 1950s
● Clip on coolant nozzle became available for hand piece around 1950.
● Tubing attached by clamps to the engine arm, led back from these nozzles
to a special spray generating atomizer, and the patients presses the button
of an air valve at the dentist’s request to release spray as the bur starts to
cut.
● In the later versions, the spray atomizer was activated by electric solenoid
valve so that emission of spray occurred simultaneously with bur rotation.
28. ● In 1954, spray cooling handpiece came in to use.
● Additionally air syringe fitted with twin nozzle rather than single nozzle
came into use.
● In a prototype assembly, an auxiliary switch box fitted to the pedal of the
unit foot control provided air from one hand piece nozzle on partial
elevation of operator’s foot, whilst full elevation results water spray to be
delivered from other nozzle.
● Patents on this development were filed in 1955, and the Amalgamated
Dental Company marketed it for attachment to the dental units of day
calling it the ‘NEW ERA,’
29. Fig- KaVo "Imperator" contra angle
handpiece, for No. 2 slipjoint, No. 1122,
chrome plate, by Drendel and Zweiling,
Germany, 1955-1965
30. ● In the mids 1950s, complex speed increasing handpiece were also devised
such as D and Z Type RT 150 hand piece in which two nylon neoprene belts
transmitted the drive progressively from larger to smaller pulleys the
inside the hand piece to give rise to 6:1 speed increase.
● When fitted to a 3:1 speed increasing slip joint a bur speed of 120000 rpm
was obtained.
● Another principle was employed in 1951 to reduce vibration in the grinding
enamel, this was the D and Z Imperator system in which the shank of
diamond points,wheels and discs were enclosed by sleeves, forming the
forward end of the handpiece and being locked in placed by engaging a
single ball bearing in an indent by twisting a knurled ring.
31. ● This system eliminated eccentric rotation and allowed smooth efficient
grinding of enamel for crown preparation under water spray at speed up to
30000 rpm.
● The ingenious Imperator locking mechanism is still employed today for
connecting handpiece heads to angle shanks driven by micromotors.
32. Modern refinements
● In november 1956, at the French Dental Congress in Paris, Ivor Norlen, a
Swedish dentist introduced DENTALAIR - a beautifully engineered control
assembly bearing two air driven handpiece on polythene tubes.
33. ● In 1956 the first clinically successful air-driven turbine handpiece became
available with speeds of approximately 300,000 rpm.
● It was introduced by Dr. John Borden.
34. ● Several prototypes were made, one of which was sent to the Amalgamated
dental company in london (1957).
● It was an elegant handpiece with a head rotor supported by 2 ball bearings,
an integrated water jet for cooling and a polythene tube in the bur bush to
grip the bur shaft, nylon tongs being used to exchange the burs.
● The brilliance of the invention included the changing of the time- honored
bur shaft diameter of 2.350mm, to a smaller shaft diameter 1.6mm. This
enabled commercially available miniature ball bearings to be used.
● The control assembly for this instrument comprised an air filter, a
pressure regulator and an oil mist lubricator, these pneumatic components
having already being developed for industrial application.
36. ● It was now possible that, with a tungsten
carbide bur of only 1mm in diameter, and with
a speed of 300000 rpm any fissure can be cut
down efficiently whilst the patient feeling any
viibratory perception.
● The main improvement made was to provide the
rotor and bearing assembly in the form of an
replaceable capsule.
37. AIRROTORS OF 1960s
● It was that around 1960s, the Intra handpiece was introduced by KaVo.
● It was a slip joint handpiece comprising a body portion to which different
angle or straight heads were attached by a bayonet type joint.
● The shaft of the body portion terminated in double crown wheel.
● The significance of Intra system was that the body portion of handpiece,
rather than connected to a cord arm wrist joint, could obviously
incorporate a small driving motor having the same bayonet attachment for
the Intra heads.
● It could thus be possible to entirely eliminate the cumbersome ball
motor,cord arm and wrist joint assembly.
38. ● One of the eg were- DENTATUS AIR
MOTOR.
● Their main drawback was that they
were noisy to use.
Figures-
15- Ka Vo INTRA slip joint handpiece 1960
16a - DENTATUS air motor with Ka Vo 3:1
speed increasing contra angle head
connected to a motor by intra bayonet
attachment.
16b - Interior of DENTATUS motor showing
Ball piston in eccentric rotor engaging
in indents of driving rings.
39. ● In the 1961st, SERVO motors were introduced, the operated on currents as
low as 24 volts DC, risking neither the patient nor the dentist the danger of
being electrocuted.
● They have a top speed of 20000 rpm.
● The drawback was that, when one reduce the speed the torque fell off.
● The second prototype was constructed in the early 1962s, was more elegant
- the servo motor being of smaller diameter, with a direct intra fitting
accepting both straight and angle heads replacing the slip joint.
40. ● In the 1965, the RITTER Company incorporated Kerr motors into their own
casing.
● Following the Kerr Electrotorque came a succession of reliable electric
handpiece micromotors from dental equipment manufacturers such as the
TORX motors made by MORITA of JAPAN.
● Siemens designed their SIRONA electric micromotor to have a top speed of
12000 rpm, double that of Kerr Electrotorque.
● Throughout the 1960s most turbine handpieces made by different dental
companies had more or less the same 300000 rpm running speed and the
same low torque as original BORDEN airotor.
41. Fig - Ritter KERR electric handpiece motor with bayonet attachment for Ka Vo
intra heads 1965
42. AIROTORS IN THE 1970s
● In the 1971st, a high torque turbine handpiece was designed by Ka Vo
Company.
● It had a large diameter head 13mm by comparison with the usual 9-10 mm
diameter head of Borden type turbine.
● Six prototype was made which had been trailed by several dentist in
Germany, all reporting the head to be very big. So nicknamed - JUMBO.
● After two years, in 1973, Ka Vo produced the VARIOAIR air flow control
coupling for the super torque which provided the precise speed for enamel
cutting 300000 rpm reduced to 230000 rpm for intact dentin cutting and
150000 rpm for soft carious removal.
43. ● A further development employed the Vane motor principle: incoming air
attempting to expand the rotor, having radial slots containing sliding
vanes, to move round to provide a greater volume of inter-vane space until
another vane passes the inlet port when the cycle is repeated.
● Eg - the Ka Vo L- motor, having an adjustable speed setting and accepting a
variety of push-on handpiece attachment, providing high torque
throughout a speed range up to 20000 rpm due to the full force of
incoming air being applied to the five vanes of its small diameter rotor.
44. IN TO THE 80s
● Three significant advances in handpiece development have occurred in this
decade-
1. The push button chuck
2. The multiple coupling and
3. Fibre optic lighting
● The progressive development of handpiece to cable coupling made, for eg
Ka Vo to overcome the disadvantages began with the REVOLVAIR coupling
which enabled the handpiece to swivel on its cable.
● The later QUICK coupling provided both for swivel and also for easier
exchange of handpiece at bayonet type twist joint.
● The most recent development is the MULTIFLEX coupling.
46. ● Air and water connections for spray cooling are automatically made on
attachment of the handpiece to the coupling and, in addition , the tip of
coupling may house a small fibre-optic light transmission through each
handpiece connected to it.
● One of the first commercially- available optic systems was produced by
VOLPI Company of Switzerland in the 1970s.
● The light being conveyed down thin tub having a clip -on attachment for
the turbine handpiece.
47. ● Although the twin spotlight arrangement has been adopted by most
manufacturers, the Japanese NSK Company has developed an interesting
alternative concept in their OPTICA System in which the light emerges
from the circular source on the underside of the turbine handpiece head.
● An obvious feature of this system is that no shadow is produced on any
part of the illuminated tooth during cavity preparation.
● Beside this, many company has produced high torque, conventional speed
range handpiece which incorporates all this recent developments.
● For eg- Ka Vo INTRAFLEX LUX range
49. THE 21st CENTURY AIROTOR
● Keeping patient and personal well-being at the forefront, a few factors
must be considered when selecting the ideal airotor handpiece for clinical
practice.
● 1. Head Size:Dimensions
Full-SizE- 14.5 mm x 13.0 mm
Mid-Size- 11.9 mm x 10.2 mm
Miniature- 9.8 mm x 8.5 mm
Full-size airotor handpieces incorporate a larger turbine impeller with higher
torque and power output. More cutting power equals less time involved in tooth
preparation.
50. ● Small head-size airotors improve visibility and access, especially in the
posterior region and with children. However, when a long bur is used in a
small head airotor; it can exert significant lateral stresses on the turbine
reducing the life expectancy of the cartridge.
● 2. Head Angulations:
- The standard dental airotor head is angled back at 22.5°. This guarantees
that the bur will always be in the clinician’s line of sight.
- The back end of the handpiece head may occasionally make premature
contact with teeth in the opposing arch, limiting access to posterior teeth.
- In order to improve posterior access and patient comfort, newer designs
have a unique head angle.
51. ● 3. Types of Tubing Connection: the base of the airotor handpiece has holes,
each of which serves a distinct purpose.
- 2-hole handpiece: Usually the standard in India where the large hole is for
air and the smaller hole is for water. As there is no port for used air to
escape such airotors are loud.
- 4-hole handpiece: Usually the standard in the U.S. and Europe. It has two
large holes for air intake and air escape which ensures less noise and allows
the bur to halt faster upon releasing the foot pedal. The other holes serve
the function of water intake and chip air which ensures the water jet escape
as fine mist and not water droplets.
● A simple coupler can be used to transform a 2-hole handpiece into a 4-hole
one.
52. ● 4. Bur retention mechanism:
- Standard Screw-Type: The spindle and chuck are separate and a chuck
device is used to insert and remove the bur.
- Push Button-Type: The spindle and chuck are a single assembly and a
push button cap on the handpiece head is used to open or close the
chucking mechanism. This is easy to use and time saving.
● 5. Ball bearing material:
The heart of the turbine is the delicate ball bearings. Usually fabricated in
either stainless steel or ceramic. Ceramic is usually the preferred choice as
it is harder, weighs less with greater abrasion resistance and thus longer
life expectancy.
53. ● 6. Ergonomic Design:
Handpiece shell can be either knurled or smooth. The knurled finish
handpiece improves grip with gloves. It is important that the knurling not
be too deep or too close so as to compromise handpiece cleaning and
sterilization
● 7. Water Delivery:
A water jet helps keep the prepared tooth cool and helps eliminate debris
from the operating site. A multiport spray originating from the face of the
handpiece is far superior than a single water port as they have a
significantly higher cutting rate.
● 8. Light Source:
Better visibility of the operation site is always desirable. Instruments with
an integrated light source that directly illuminate the site have a
significant impact on the quality of patient treatment
54. CONCLUSION
● No instrument in the dental history has attracted dentistry and dentist
over the past century than dental handpiece.
● Fear of the drill has progressively disappeared in recent decades, the latest
breakthrough is the Speed-Sensing Intelligence, it actually monitors the
bur speed several hundred times per second.
● A sensor in the coupler detects the frequency of vibrations from the
rotating bur. When the bur encounters a higher load that would normally
decrease speed, a signal from a small chip in the control source increases
air pressure to maintain speed, virtually eliminating stalling to provide a
smooth, consistent cutting speed regardless of load.
55. ● This design provides exceptionally fast removal of tooth structure,
amalgam, porcelain, and metal.
● Because the system adjusts speed when the bur is not under load, wear on
bearings is minimized, which means fewer turbine, thanks to the
continuous
development and improvement in the design and construction of
handpieces
56. REFERENCES
● Gopal, Shankar & Rajasekaran, Meenakshi & Kavitha, Loganathan & B,
Venkatesh & GP, Anu. (2023). EVOLUTION AND MECHANISM OF DENTAL
HANDPIECES. International Journal of Multidisciplinary and Current
Research. 10. 65659-65664.
● Evolution of instruments in Conservative Dentistry.Batch 2019-2022. P 76-
103A Library Dissertation by Dr. Arun Rana
