1. The document discusses speeds used in operative dentistry, classifying them as low, medium, and high speeds. It describes the historical development of dental handpieces and how they have evolved from manual to electric to air-driven designs. 2. Common handpiece types include straight, contra-angle, and right-angle handpieces, each suited for different procedures. Bur designs influence cutting efficiency factors like rake angle, clearance, and number of teeth. 3. Low speeds below 20,000 RPM are used for procedures like caries removal that require tactile feedback, while high speeds above 160,000 RPM allow faster cutting with less pressure and heat for cavity preparations.

1. SPEEDS
IN OPERATIVE DENTISTRY
 GUIDE:DR.RISHI MANAN
 CO-GUIDE:DR.NIKHIL PURI
 PRESENTED BY-
DR. AJAY BABU GUTTI
2ND MDS

2. CONTENTS
 Introduction
 *Definition
 *Classification
 *Armamentarium used in procedures involving speed
:- 1) Historical aspect of development of armamentarium .
:- 2 ) Recent developments
:- 3) Non-rotary equipment for cutting tooth structure
 *Application of high speed and low speed
• Instrument design : 1. Handpiece 2. Dental burs
 *Characteristics of rotary instrumentation and significance
 *Cutting mechanisms : 1. Bladed cutting
2. Abrasive cutting
 *Cutting evaluation and recommendation
 *Hazards with cutting instruments
 *Management of equipment
 * Summary
22

3. INTRODUCTION
 Speed as a general term is the rate at which a certain
activity/ event/ procedure takes place.
 The term SPEED in dentistry has greater importance in all the
treatment procedures.
 The action of speed is primarily through rotary
instrumentation

4. DEFINITION
 •According to Sturdevant “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 .”
 •According to Marzouk “Speed not only refers to revolutions per
minute but also to surface feet per unit time of contact that the
tool has with the work to be cut .”

5. What is an handpiece ?
 A hand piece is a - device for holding rotating
instruments, transmitting power to them and for
positioning them intra orally.

6.  The dental hand piece is used in operative and
restorative dentistry
 to cut tooth structure for various types of preparations.
 to remove old metal restorations
 to polish teeth and finish various types of restorative
materials.
 The hand piece may also be used in oral surgery
and for implant procedure.

7.  Most development of methods for preparing
teeth has occurred within the last 100 years
.effective equipment for removal and
preparation of enamel has been available
since 1947. speeds of 10,000 rpm were first
used along with newly marketed carbide
burs and diamond instruments.
 Since 1953 continued improvements have
results in equipment that is efficient as well
as sterlisable.

8. HISTORY / EVOULTION
 1868 – Dr.Jonathan Taft in his text
book of operative dentistry. Cutting
procedures on tooth enamel and
dentin were carried out using thick,
bulky chisels and excavators.
 The first rotary instruments used for
cutting tooth tissue were actually
drill or bur head that could be
twisted in the fingers, for a cutting
action. He described them as “bur
drills”.

9.  One of the refinements of
these bur drills was scrantons
drill. This could be rotated in
either direction to achieve its
cutting action.
 The next modification was drill
ring.

10.  1871 – Morrison modified and adapted the dental
foot engine from the singer sewing machine. For the
first time, cutting procedures were carried out with
a power source.
 1883 – electric dental engine linked to the hand
piece by a flexible cable arm was introduced.
 1910 – belt driven hand piece was introduced
 1950 – ball bearing hand piece was introduced

11.  1953 – nelson introduced, first fluid turbine type hand piece
with speed of 50,000 rpm.
 1954 – air driven hand piece were developed with possible
speed of 150,000 rpm.
 1957 – rotational speed was increased to 300,000 rpm
 1960’s – introduction of air bearing hand piece with speed of
500,000 rpm.
 1963 – ultrasonic method of tooth tissue removal with
vibrating frequency ranging from 15,000 - 30,000 cycles /
second.

14. CLASSIFICATION OF SPEED
ACCORDING TO STURDEVANT
 Low or slow speed - below 12,000 rpm
 Medium or intermediate speed - 12,000
to 200,000 rpm
 High or ultra speeds - above 200,00 rpm

15. ACCORDING TO CHARBENEAU:
 Conventional or Low speed - below 10,000 rpm
 Increased or high speed - 10,000 to 150,000 rpm
 Ultra speeds - above 150,00 rpm
ACCORDING TO VIMAL SIKRI:
 Conventional or Low speed - below 6,000 rpm
 Intermediate or high speed - 6,000 to 100,000 rpm
 Ultra or Super speeds - above 100,000 rpm

16. ACCORDING TO MARZOUK:
 Ultra -Low speed- 300 to 3,000 rpm
 Low speed-3,000 to 6,000 rpm
 Medium High speed- 20,000 to
45,000 rpm
 High speed- 45,000 to 100,000 rpm
 Ultra high speed- 100,000 rpm and
more

17. HANDPIECES AS PER SPEED
LOW
SPEED
1:1 ratio
contra-angle
1:4 ratio
speed-
increasing
handpiece
7:1 ratio
speed-
reducing
handpiece
straight
handpiece
AIROTOR
250000-
500000rpm
ACCORDING TO KIDD
How do we classify handpiece?

18. 1:1 ratio contra-
angle handpiece
1:4 ratio speed-
increasing
handpiece
7:1 ratio
speed-
reducing
handpiece
A straight
handpiece
BURS
USED
Latch-
grip
friction-
grip
Latch-
grip
straight burs or
latch-grip
IDENTIFIED
BY
a blue-coloured
band on the
shank of the
handpiece and a
blue dot on the
head.
red
band
green
bands
A 1:1 ratio handpiece
is identified with a
blue band and
reducing speed is
identified with a
green band.
SPEED
RANGE
400–40 000
rev/minute.
16000–160000
rev/min
550–5500
rev/min
USED
Caries
removal
finishing cavity
preparations
and also
finishing
restorations.
drilling pin
holes
To trim temporary
restorations .
Usually used
outside the mouth

19. 1:1 ratio contra-
angle handpiece
1:4 ratio
speed-
7:1 ratio
speed-
Increasing Reducing
handpiece handpiece
straight
handpiece

20. LOW SPEED HAND PIECE
 Speed ranges from 10,000 to 30,000 rotations per minute
(rpm)
 Low speed hand piece
• Straight
• Contra angle
 The speed of these hand piece is less but the torque is
greater.
 Low speed hand pieces can be rotated clockwise or
anticlockwise, where as airotor only rotates clockwise.

21. USES
 Low or slow speed  cleaning teeth, occasionally
caries excavation finishing and polishing
procedures.
ADVANTAGES –
 At low speeds, tactile sensation is better and
there is generally less chances for over heating
cut surfaces.

22. DISADVANTAGES
 Cutting is ineffective, more time consuming and
produces vibrations of low frequency and high
amplitude.
 Heat and vibrations are the main sources of
patient discomfort.

23. HIGH SPEED HANDPIECE
Operates at speeds up to 450,000 rpM
 Tooth preparation
 Removing old restoration.
 with high speed cutting instruments removal of tooth
structure is faster with less pressure, vibration and
heat production.
 Patients are generally less apprehensive because
annoying vibrations and operating time are decreased
Variable control to regulate the speed makes the hand
piece more versatile. This allows the operator to
easily obtain the optimal speed for the size and type
of rotating instrument at any stage of a specific
operation.

24. DIFFERENCE BETWEEN LOW
SPEED AND HIGH SPEED
HANDPIECES
LOW SPEED HANDPIECE
 Power source is electric motor
 Possible to vary the speed of
the bur
 Slow speed handpieces require
pressure during use
 Slow speed handpieces have
high torque
 Coolant system is external
HIGH SPEED HANDPIECE
 Power source is compressed air
 Speed cannot be varied
 Require feather touch brushing
strokes.
 High speed handpieces have low
torque
 Coolant system is always internal

25.  Dental hand pieces classified according to driving
mechanism
• Gear driven hand piece
• Water driven hand piece
• Belt driven hand piece
• Air driven hand piece

26.  Depending upon angulations
• Straight
• Contra angled
• Right angled
Each is designed
for a specific
range of functions

27.  Straight hand piece  the straight hand piece may
also be used with a straight shank. Rotary
instrument on anterior teeth or where a direct
approach to teeth is possible.

28.  Contra angled hand piece  is designed to provide
the operator with greater accessibility to the oral
cavity during operative dentistry.
 Right angle hand piece  in which the head of the
hand piece forms a 90o angle to the shank. The
most popular right angle hand piece is the prophy
angle.

29. RECENT DEVELOPMENTS IN HANDPIECE
 Illumination : use of light emitting diode. LED s are relatively stable in
wavelength and consume low power and produce little or no heat.
 Size of head : the size of the head of handpiece can be reduced for ease of
access without compromising torque. There are several head sizes of high
speed handpieces are available ranging from 9.8 x 8.5 mm to 14.5 x 13 mm.
 Head angulation: The typical hand piece head is angled back at 22.5 degrees
so that the cutting instrument remains in line with the operator’s line of
sight.
29

30.  Three hole handpiece : the two holed handpiece was later
modified to three holes.
The third one acted as a vent to let out the excess air that is
collected in the head of the handpiece so that the coast speed is
substantially reduced and the bur comes to a halt at the earliest.
30

31.  Autoclavability:
 Handpiece manufacturers are constantly seeking improvement in
their handpiece designs to better withstand the harmful effects
of the autoclave
 Multiple water spray ports
This provides even distribution of coolant water over the entire
surface of the tooth and prevents the water spray from being
blocked when cutting is performed on the distal surface of a tooth.
31

32. Application of
varying speeds in
dental procedure

33. caries excavation
RPM USED 500-800
Finishing and
polishing of
restoration
20,000- 40,000
intracanal
instrumentation
using rotary files
RPM 250-500
LOW SPEED : used for

34. USES OF
LOW SPEED
34
Refining the
cavity
preparation
in inlay
RPM 20,000-
40,000
Finishing of composite
restorations and
refinement of cavity
preparation
RPM 20,000- 40,000
Preparation of
pinholes for
complex amalgam
restorations
RPM 300-500

35. 35
oral prophylaxis
Rpm upto 10,000
Implant
placement
RPM 800-1000

36. DISADVANTAGES
 Ineffective
 Time consuming
 Requires relatively heavy force application at the operating site.
 Produces vibrations causing patient discomfort.
 Slower cavity preparation which increases operators fatigue & patients
discomfort.
 Burs have a tendency to roll out of the tooth preparation
 Carbide bur blades break easily at low speeds-Brittle blades
ADVANTAGES
• Better tactile sensation
• Less chance for overheating cut surfaces

37. MEDIUM SPEED
USES:
•Cavity preparation
•Placing retentive grooves and bevels
•For areas of limited visibility
ADVANTAGES:
•Positive tactile sense
•Controlled cutting of tooth structure
DISADVANTAGES:
•Slower cavity preparation which increases operators fatigue & patients
discomfort.
• Increased heat production.

38. 38
ACCESS CAVITY
PREPARATION
Rpm 2,30,000
CROWN
PREPARATION FOR
INDIRECT
PROSTHESIS
1,60,000-
2,30,000
HIGH SPEED: used in
HEMISECTION
Rpm 2,50,000
GROSS SHAPING
AND POLISHING
OF CURED RESIN
RESTORATION
1,60,000 rpm

39. Advantages
1. Cutting instruments remove tooth structure faster with less
pressure, vibration & heat generation
2. Number of rotary cutting instruments needed is reduced because
smaller sizes are more universal in application
3. Greater ease of operation for operator.
4. Instruments last longer
5. Patients are generally less apprehensive because annoying
vibrations and operating time are decreased
DISADVANTAGES
•Less tactile sense so overcutting possible
•Air –water spray can impair visibility
•More chances of iatrogenic errors

41. AIROTOR BEARING
Ball/ needle/ glass/ ceramic :
reduce friction in turbine at
high speeds within a cage
BEARING HOUSING/CAGE
It is the raceway of the
bearings, and retains them.
TURBINE
Powered by compressed air
usually 43psi . Turbine
rotates, bur rotates
consequently 41

42. GENERAL DESIGN OF
DENTAL BURS
A. Bur tooth : terminates in the cutting edge or blade
B. Rake angle: it is the angle that the bur tooth makes with
the radial line from the centre of the bur to the blade.
C. Land : plane surface immediately following the cutting
edge.
D. Clearance angle : angle between the back of the tooth
and work.
E. Tooth angle : measured between the face and back if land
is present
F. Flute or chip space : space between successive teeth.

43. 43

44. INFLUENCE OF
DESIGN
1. Rake angle : more positive the rake angle the more greater is
the cutting efficiency
2. Clearance angle : any slight wear of cutting edge will
increase the dulling perceptibility
3. Number of teeth of blades and their distribution: as the
number of blades decrease the magnitude of force at each
blade increases and thickness of chip removed by each flute
correspondingly increases.

45. 4. Run-out : refers to eccentricity or maximum displacement of bur
head from its axis of rotation while the bur turns
5. concentricity is defined as the ability of the handpiece to
produce a cutline consistent with the diameter of the bur. (ISO
Standard 7785-1 - Dental Handpieces. Geneva,
Switzerland:International Standards Organization; . )
6. Finish of the flutes
7. Heat treatment : used to harden a bur which is made of soft
steel . This procedure preserves the edge placed on the bur flute,
increases cutting life.

46. Bur diameter
10. Depth of engagement
11. Influence of load: the minimum and maximum loads for
low speed are 1000-1500 gm, while that for high speeds are
60-120 gm
12. Influence of speed: rate of increase in cutting at rotational
speed above 30,000 rpm is greater than that below this speed.

47. TORQUE:
•Torque is the turning movement of the instrument
•Torque is the ability of hand piece to withstand lateral pressure
on the revolving tool without decreasing the speed or its cutting
efficiency .
•The speed is inversely proportional to the torque
•It is more efficient to cut hard materials such as enamel,
porcelain,and metal at high speeds with lower torque & softer
carious dentine at lower speeds with higher torque.

48. FRICTION
 Will occur in the moving parts of a hand piece especially
the turbine.
 If the heat from friction is not prevented or counteracted,
the hand piece will be unsuitable for dental use.
 For this reason bearings are used: ball bearings, needle
bearings, glass and resin bearings etc.

49. VIBRATION
 As vibration is a very deleterious aspect of rotary instruments so the
care to be taken not to introduce it unnecessarily.
 Excessive wear of the turbine bearings will cause eccentric running
which creates substantial vibration.
PRESSURE
Speed is inversely proportional to the Pressure.
Cutting at:
 Low speed ranges ~ 2-5 pounds
 Higher speed ranges ~ 1 pounds
 Ultra High speed ranges ~ 1-4 0unce

50. TACTILE SENSE:
•An important characteristic of cutting systems is the ‘feel’ which the
operator senses through the hand piece.
•At high speed there is very little ‘feel’ and the cutting must be
controlled visually which is difficult because of the water
spray.
•At lower speeds ‘feel’ is useful in controlling the cutting process,
particularly close to the pulp. This is the principle reason why low-
speed sharp burs should be used for removing carious dentine.

51. SPEED & RATE OF CUTTTING:
•At a given load, the rate of cutting increases with the rotational speed but not
in direct proportional.
•The rate of cutting is more at speeds above 30,000 rpm than that below
this speed.
•However at speed more than 1,50,000 rpm rate of cutting is nearly same
as at still higher speeds.
•There is also a minimum rotational speed for a given load below which
the tool will not cut.
• The greater the load , the lower this minimum rotation speed will be.

52. HEAT PRODUCTION:
Heat is directly proportional to:
RPM
Pressure
Area of tooth in contact with the tool.
•Dry cutting with air-cooling only is reported to contribute to
increasing temperatures that negatively affect the pulp and
cause cracking of the Enamel and Dentin.

53. 130 F
PERMANENT
DAMAGE TO
PULP
113 F
INFLAMMATORY
RESPONSE OF
PULP
PULPITIS
PULPAL
NECROSIS
EFFECT ON PULP :

54. COOLANT SPRAY SYSTEMS
 A considerable heat is generated when an air turbine is cutting
teeth. This heat has to be removed rapidly from the cutting site.
 All current hand piece have provision for an air-water spray from
closely positioned air and water jets to be directed onto the rotary
cutting for cooling and clearance of debris.
 Some hand piece have tubes carrying water and air separately or
even a single water / air nozzle combination.
 Some hand piece have a single nozzle and some hand piece have
multiple water – air nozzles which equally spaced around the head.

55. EVALUATION OF CUTTING
CUTTING
EFFECTIVENESS
 Cutting effectiveness is
the rate of tooth
structure removal
(mm/min or mg/sec)
 Does not consider
potential side effects
such as heat or noise
CUTTING
EFFICIENCY
 Cutting efficiency is
the percentage of
energy actually
producing cutting
 Cutting efficiency is
reduced when energy
is wasted as heat or
noise 55

56. Rotary niti instruments speed
Instruments Speed of the
instruments
Advantages
Light speed 750 -2000 RPM Remain central in
canal minimum
transportaion ,elbow
formation
Profile ISO sized
instruments
150-300 RPM Preservation natural
canal path cutting
effectiveness,
tapered preparation
Protaper 300RPM Superior flexiblity
Hero 642 500- 600 RPM Doesn’t create
blockage
RaCe 300-600 RPM Used for both step
back and step down
Useful in calcified and
narrow canal

57. Morita trio Auto –ZX
 Cordless , Battery Powered Endodontic , Slow
Speed Handpiece With A Built In Apex Locator .
 Three Automatic Function
 Starts Automatically When The File Enters The
Canal And Stops When The File Removed .
 If Too Much Pressure Is Applied The Handpiece
Stops Automatically And Reverses The Rotation
 It Also Stops And Reverses Rotation When The
File Reaches The Apical Stop ,Which
Determined By The Built In Apex Locator.

58. RECIPROCATING HANDPIECE
 Accepts only latch type of instruments
 The quarter turn motion deliveres 3,000 times per minute
 Kerr , M4 handpiece which has 30 degree reciprocating
motion
 Endo gripper handpiece has 10:1 gear ratio and a 45 degree
turning motion.

59. ULTRA SONIC HANDPIECE
A system has an energy source 20 to 25 kh .It
activates endodontic file, resulting in three
dimensional activation of the file in the
surrounding medium .

60.  Design of ultrasonic
handpiece
 Attached to the dental
unit.
 Powered by electricity.
 Primarily used for
prophylaxis appointments.
 Attachments are similar in
appearance to scaling
instruments.
 Delivers a pulsating spray
of water.

61. Uses of the Ultrasonic Handpiece
 Remove calculus
 Remove stain
 Remove bonding materials from tooth surface after
orthodontic appliances are removed
 Remove cement after orthodontic bands are removed

62. Sonic Handpiece
The sonic handpiece available today is micro mega 1500 or
1400 sonic air endo system
The air pressure may be varied with an adjustable ring on
the handpiece to give an oscillatory range of 1500 to 3000
cycles per second .

63. CUTTING RECOMMENDATIONS
 Requirements for effective and efficient cutting include
 using a contra-angle handpiece,
 Air-water spray for cooling
 High operating speed > 2,00,000 rpm
 Light pressure
 Greater rpm
 Smaller cutting tool
 Less force
 effective lubrication

64. HAZARDS WITH
CUTTING INSTRUMENTS
Pulpal
precautions
Soft tissue
precautions
eye
precautions
Ear
precautions
Inhalation
precautions
64

65. PULP PRECAUTIONS
 Use of cutting instruments can cause harm to the pulp
 Mechanical vibration
 Heat generation
 Dessication
 Loss of dentinal tubule fluid
 Transection of odontoblastic process

66. SOFT TISSUE
PRECAUTIONS
 Lips, tongue, cheeks of the patient are most frequent
areas of soft tissue injury
 Operator must be extremely careful with the handpiece
so as to not lacerate soft tissues
 Electric handpieces have a possibilty of over-heating
which may cause mucosal burn injuries

67. EYE PRECAUTIONS
 To prevent eye damage, glasses with eye shields should
be worn by patient as well as the dentist
 When high speeds are used particles of old restorations,
tooth structure, bacteria and other debris are discharged
at high speed from the patient s mouth.

68. EAR PRECAUTIONS
 Air-driven handpieces with ball bearings, free running at 30-
lb air pressure may have noise levels at 70-94 db at high
frequencies
 Noise levels greater than 74db may cause hearing
impairment
68

69. INHALATION PRECAUTIONS
 Aerosols and vapours are created by cutting tooth structure
and are a health hazard
 Vapour from cutting amalgams is predominantly mercury and
should be eliminated, as much as possible, by high speed
evacuation
69

70. MANAGEMENT OF
EQUIPMENT
 During the period of warranty the dentist has to follow
the manufacturer’s instructions and lubricate the
handpiece with the lubricants supplied by the
manufacturer.
 During autoclaving or sterilization procedures one must
also follow the manufacturer’s instructions as far as the
temperature to which the handpiece can be subjected
to.

71.  Expel excess lubricant by running the handpiece after
lubricating and before autoclaving. This is important. If the
handpiece isn’t run to expel the lubricant, it can cause a
gumming effect around the turbine where it will be
essentially baked in.
 Let the handpiece cool down. Never run the handpiece under
cold water to quickly cool it off. This damages the turbine.
 It is important to follow the manufacturer’s guidelines on air
pressure. Excessive air pressure could cause damage to the
turbine bearings.

72.  The association for European safety and infection control in
dentistry recommends adequate external cleaning and
disinfection in a washer disinfector and in addition some form
of internal cleaning and disinfection.
 The lubricant should be safe to use in conjunction with steam
sterilization at 135 degree Celsius.
 As far as lubrication of the handpiece is concerned most
clinicians would prefer the bur in the handpiece. Lubrication
can be carried out either before or after sterilization.

73. REFERENCES
 STURDEVANTS ART AND SCIENCE OF OPERATIVE DENTISTRY
 MARZOUK TEXTBOOK OF OPERATIVE DENTISTRY
 FUNDAMENTALS OF OPERATIVE DENTISTRY : SUMMITT,
ROBBINS
 CHARBENEAU TEXTBOOK OF OPERATIVE DENTISTRY
 OPERATIVE DENTISTRY : Vimal k.Sikri
 High speed handpieces. J Int Oral Health 2014;6(1):130-2.
 Anatomy of a handpiece, ADA CERP , peer-reviewed publication,2010.

74. SPEED IS CALCULATED AS MILE PER
HOUR …. BUT LIFE IS CALCULATED
AS SMILE PER HOUR …. SO INCREASE
YOUR SMILE AND GET EXTRA
MILAGE IN LIFE…”