Rotary instruments / dental implant courses by Indian dental academy

INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

CONTENTSCONTENTS
 Introduction
 History and development
 Principles of Rotary instruments
 Instrument Parts and Design
 Instrument types
 ISO Standardization
 Manufacturing
 Efficiency
 Clinical Considerations
 Recent advances
 Sterilization and Infection control
 Summary
 References

INTRODUCTIONINTRODUCTION
The removal and shaping of tooth structure is an essential
part of restorative and prosthetic dentistry. Initially this was
a difficult process accomplished entirely by the use of hand
instruments. The introduction of rotary equipments, air
abrasives and lasers is one of the truly major advances in
dentistry.

Rotary cutting instruments:
They are engine driven instruments revolving around their long
axis.
Bur :
A cutting or drilling bit .
(Webster’sDictionary)
A surgeon’s or dentist’s small drill.
(Oxford Dictionary)
A steel or tungsten carbide rotary cutting instrument.
(GPT-7)
Diamond points:
They are rotary cutting tools, consisting of an inner steel
shank over which industrial diamonds of different grits are
either electroplated with Ni or are sintered with a metal
matrix.

HISTORY AND DEVELOPMENTHISTORY AND DEVELOPMENT
“The only guide to what lies ahead is in the past.”
5000 B.C.
Early drills from the time of
Hippocrates
287-212 B.C.
Archimedian instruments

1700s
Mechanical drilling device
turned with a hand crank
Invented by Jourdain and
described by Fauchard
1790
First foot- powered dental
engine by J.Greenwood

1803
Crank operated gear
drill by Von
Lautenschlager
1838
Egg-beater drill
invented by J.Lewis
First patented drill www.indiandentalacademy.com

1846
Wescott introduced the
finger ring with drill
socket
1850s
G.F.Green invented the first
electric dental engine with a self
contained motor and hand piece

1858
Charles Merry introduced
this drill stock with two
hand pieces :one retained
the rotating drill in
position, the other
propelled it.
1864
Harrington
introduced the first
motor driven dental
engine

1870
George F.Green
invented the first
electric dental
engine, was a self
contained motor and
hand piece
1871
James B. Morrison
invented the foot-treadle
dental engine

1874
Bonwill dental engine-
the first continuous cord
engine with
compensating points
1875
S.S. White Dental Engine-
Battery operated

1902
First folding bracket engine
Cord type Cable typewww.indiandentalacademy.com

Around 1915
Dariot hand piece
used with continuous cord
dental engine
1950s
S.S. White hand piece no.7
Used with cable dental
engines

1950s
Midwest needle ball-bearing
hand piece with Trans speed
of 50,000 to 100,000 rpm
1950s
Airbrasive non rotary
drills were introduced

1958
Page-Chayes hand
piece –the first belt
driven hand piece
1950s
Turbo-Jet
-the first water
driven turbine hand
piece www.indiandentalacademy.com

1957
Borden Airotor Hand piece-the first air-driven hand
piece with a running speed of about 300,000 rpm
In Modern times:
LASERS have also been considered as an option

PRINCIPLES OF ROTARYPRINCIPLES OF ROTARY
INSTRUMENTSINSTRUMENTS
SUBSTRATE
ROTARY CUTTING
INSTRUMENT
SHEAR AND TENSILE
STRESSES INDUCED IN BOTH
IFSTRENGTH OF
CUTTING SURFACE >SUBSTRATE
INSTRUMENT WILL
CUT, GRIND OR POLISHwww.indiandentalacademy.com

ABRASION
 Abrasion : Process of finishing a restoration involving
abrasive wear through the use of hard particles.
 Abrasive : A hard substance used for grinding, finishing or
polishing a less hard surface.
 Substrate : The material being finished by an abrasive.
 Rotational direction is an important factor in controlling the
instrument action on the substrate surface.
 Two processes : Two body abrasion
Three body abrasion.
 Hardness of abrasive should be higher than the substrate.
 Mohs scale : Diamond – 10
Tungsten carbide – 9.8
Enamel – 5
Dentine – 3 to 4 .
 Speed for-cutting : 5000 feet per min
-polishing : 7500 to 10000 feet per min.www.indiandentalacademy.com

CUTTINGCUTTING GRINDING
FINISHINGFINISHING POLISHING

INSTRUMENT PARTSINSTRUMENT PARTS
Bur head : the cutting portion of a dental
bur.
Bur head length : the axial dimension of
the bur head.
Bur head shape : the geometrical outline
form of the cutting surface edges, usually
described successively by proximity from
the shank to the tip end.
Bur shank : that component of a dental
bur which fits into the hand piece ; the shaft
section of a dental bur that may be friction
gripping or latch type in form.
(GPT –7 JPD 1999;81:56 )

 Blade or cutting edge : is in contact with horizontal
line or work .
 Tooth face : side of the tooth ahead of cutting edge in
the direction of rotation.
 Back or flank of tooth : the opposite of the face or
following surface.
 Tooth angle : angle between front and back (flank) of
the teeth of bur.
INSTRUMENT DESIGNINSTRUMENT DESIGN

 Flute space : space in between back of one tooth and front of
next tooth.
 Clearance angle : angle between a back (flank) of tooth and
work.
Primary & Secondary clearance angle are incorporated to
increase the efficiency and decrease clogging.
Primary clearance angle : angle between the tooth
and work.
Secondary clearance angle : angle between back
and work.

Rake angle : angle between front of the tooth and radial lines.
Zero rake angle(radial rake angle) – where the radial
line and the face contour correspond.
Positive rake angle : when the radial line leads the face
so that rake angle is on inside of radial line.
Negative rake angle : when the face is beyond or
leading the radial line in reference to the direction of rotation.

Positive rake angle
Thinner and sharper teeth
More temperature rise
Less life
Used for cutting soft & weak
materials.
Possesses greater efficiency
Has lesser edge strength.
Negative rake angle
Broader teeth
Less temperature rise
More life
For hard brittle materials.
Possesses lesser efficiency
Has greater edge strength.

INSTRUMENT TYPES
Burs – cutting tools
Stones or points – abrading tools (grinding )
Classification :
A)Depending upon source of power:
1. Air driven
2. Electric driven
B)Depending upon hand piece to which it is attached:
1. Screw in type
-air motor hand piece (straight)
2. Latch type
-micromotor (contra angled hand piece)
3. Friction grip type

C)Depending upon the speed of hand piece to
which they are attached:
Ultra low - 300 to 3000 rpm
Low - 3000 to 6000 rpm
Medium - 20 to 45 K rpm
High speed - 45 to 100 K rpm
Ultra high - 100 K rpm
D)Based on the material used:
Steel
Tungsten carbide
Diamond
E) According to shape

ISO STANDARDIZATIONISO STANDARDIZATION
ISO 6360 identified completely any bur In terms of :

A) Material of its working part
Stainless steel – 330
Tungsten carbide – 500
Aluminum oxide – 615,625,635
Diamond – 806,807
B) Shank form Type of
instrument
ISO Number Shank length Shank
diameter
Standard hand
piece bur
103
104
105
34 mm
44 mm
65 mm
2.35 mm
Hand piece
bur
124 3 mm
Contra angled
standard
202
204
205
206
16 mm
22 mm
26 mm
34 mm
2.35 mm
Standard
friction grip
313
314
315
316
16 mm
19 mm
21 mm
25 mm
1.60 mm
Unmounted
grinding points
900www.indiandentalacademy.com

C) Shape of the working part
Round head – 001
Inverted cone – 010
Cylindrical – 107
Conical – 168
Pear shaped – 237
Flame shaped - 243
Bud shaped – 260
Torpedo shaped – 284
Lens shaped – 303
Disks – 320
E) Largest diameter of the working part
(measured in one – tenth of mm)
008 =0 .8mm
220 = 22mm
D) Grit size
Super fine (15 microns) – 494
Extra fine (30 microns) – 504
Fine ( 50 microns) – 514
Medium Grit (100 to 120 microns) – 524
Coarse grit (135 to 140 microns) – 534
Extra coarse (180 microns) – 545

MANUFACTURINGMANUFACTURING
STEEL BURS:
These are cut from blank steel stock by means of a rotary
cutter that cuts parallel to the long axis of bur.
Bur is then hardened and tempered.
TUNGSTEN CARBIDE BURS:
Are a product of powder metallurgy.
Tungsten carbide powder is mixed with powdered cobalt
under pressure and heated in vaccum.
A blank is then formed and the bur is cut from it with a
diamond tool
DIAMOND POINTS:
1. Electrolytic deposition
2. Brazing
3. Sintering www.indiandentalacademy.com

Abrasive particles are bonded by four methods:
1. Sintering : sintered abrasives are the strongest type as
the particles are fused together.
2. Vitreous bonding : abrasives are mixed with glassy or
ceramic matrix material, cold pressed to the instrument
shape, and fired to fuse the binder.
3. Resinoid bonding : abrasives are cold pressed or hot
pressed and then heated to cure the resin. Hot pressing
yields an abrasive binder with extremely low porosity.
4. Rubber bonding : abrasives are made in a manner similar
to that for resin bonded abrasives.

Recent advances :
Chemical vapour deposition allows for the fabrication of
new burs with continuous diamond film (pure diamond
cutter without metallic binder) and offers promising
perspectives with regard to cutting ability and longevity.
(JPD 1999;82:73-9)

EFFICIENCY
Depends upon:
1. Tooth angle
2. Clearance angle
3. Rake angle
4. Speed
5. Load or pressure
SIEGEL etal studied the cutting efficiencies of diamond dental burs
using different hand piece loads with ultra high speed.
Results:
_Optimum hand piece load at bur tip :100g
_ Below it : CE decreases
_Above it : For medium grit burs : no effect
For coarse grit burs : CE increases (with increase in
temp.)
(J.Prosthod.1999;8:3-9)www.indiandentalacademy.com

6. Eccentricity
7. Run out
8. Coolants:
 Study conducted by FRAUNHOFER etal to evaluate the
effect of hand piece coolant flow rates on cutting efficiency :
Result
Use of higher coolant flow rate (25 to 44 ml per min )
increases CR .
(Operative Dentistry 2000; 544-8)

Study conducted by SIEGELetal to evaluate the
effect of coolant water containing mouthwash
additives at various concentration on cutting rate

9.Grit size
Study conducted by SIEGEL etal to compare the cutting rates of
medium, coarse, supercoarse diamond burs.
(JADA 2000;131 : 1706-10)

CLINICAL CONSIDERATIONSCLINICAL CONSIDERATIONS
LOCAL CONSIDERATIONS:
1. Heat generation
Steel greater than carbide
Diamond greater than carbide
Dull or clogged instruments will produce more heat.
VANGHN and PEYTON concluded:
-maximum temperature rise is developed with in 10
sec after operation begins.
-smaller the size of cutting instrument lower the
temperature rise
-increased pressure and increased speed increases
the temperature rise.
( JADA 1956;53:298-304 )

2. Soft tissue injury
3. Infection transmission
4. Hearing damage:
Air turbine hand piece at high speed produces high pitch.
Protection mandatory when 95 db is reached.
Normal hand piece use per day – 30 min per day.
2. Pulpal injury
Due to mechanical vibration
Heat generation
Dessication
Loss of dentinal tubule fluid
Transduction of odontoblasts
Recovery – two weeks to six months.
GENERAL CONSIDERATIONS:
1.Silicosis
Fibrotic pulmonary disease
95% aerosols less than 5 microns

Burs with guide pins :
 Enhanced percision
 Defined depth
 Minimum irregularities of finish line
(Quintessence Int 2001;32:191-197)
RECENT ADVANCES

TWO STRIPER TECHNOLOGY
FASTER CUTTING
Natural diamonds on Two striper
instruments contain more corners and
angles to produce faster cutting.
SMOOTH FINISH MARGIN
The spiral pattern stops short of the tip
to ensure a smooth margin.
INCREASED EFFICIENCY
Clearance angles in the spiral design
provide efficient removal of debris and
access for water coolant.
(Austenal Quality Dental Products)

BEVEL SHAPED INSTRUMENT

LVS SYSTEM

ANGULATED DIAMOND ROTARY CUTTING
INSTRUMENTS
-Additional method for achieving
desirable convergence angles.
-To evaluate the amount of
convergence angle that has been
produced.
JPD 2003;90:401-5

STERILIZATION AND INFECTION CONTROLSTERILIZATION AND INFECTION CONTROL
Dating back to hippocrates, health care providers declare, “Do no
harm”.
ADA code of ethics has its primary goal as, “your safety”.
CDC(Centre for disease control and prevention) and
OSHA(Occupational safety and health administration) have set
certain guide lines:
1. Physical barriers:
masks, gloves, eye wears, gowns.
2. Use disposable items as much as possible:
Disposable drapes, cups, suction tips.
Disposable diamond points are also available:
-First described by Dr. SIEGEL in 1998
-Minimizes cross contamination risks
-Cutting efficiency is comparable to conventional diamond
points
-Purchase price of disposable diamond points is less as
compared to multiuse diamond point .Cost differential is
attributed to thinner layer of electroplated metal on disposable
diamond points.
JADA www.indiandentalacademy.com

3. Cleaning instruments and equipments that are not disposable.
4. Attempt to identify as many patients as possible who are infectious
5. Use of disinfectant and sterilization procedures:
a) Hand pieces-
Both high and low speed hand pieces are best autoclaved.
Disinfectants such as 0.5% hypochlorite will damage high
speed hand pieces.
Chemical vapour pressure sterilization recommended
for ceramic-bearing hand pieces.
Ethylene oxide gas – also used for sterilization of
hand pieces.
b) Steel burs – dry heat or immersion in cold steriliant for 10
minutes prior to ultrasonic cleaning.
Diamond and tungsten carbide burs – disinfectant
solution of 0.2 % glutaraldehyde and sodium phenate
(sporicidin) for 10 minutes. Follow with cleaning in
ultrasonic bath. Then sterilization in autoclave or dry heat
sterilization.

CUTTING EFFECTIVENESS OF DIAMOND INSTRUMENTS
SUBJECTED TO CYCLIC STERILIZATION METHODS:
(JPD 1991 ;66: 721-6)
Methods studied:
1.Cold sterilization for 6.75hr in 2% glutaraldehyde(Sporicidin)
2.Chemical vapour (Chemiclave) for 20min at 132 C at 20 psi
3.Steam under pressure (autoclave) for 15min at 121 C and 15 psi
4.Dry heat (Dri-clave) at 170 C for 1 hr
Results:
1.The cutting effectiveness of rotary diamond instruments was not
influenced by sterilization methods.
2.SEM evaluation made prior to cutting and at the end of 10 cycles of
sterilization demonstrated that diamond wear was similar in all
groups and that little diamond particle loss occurred in any
group.

SUMMARYSUMMARY
When we review the history of development of tooth cutting
techniques we realize how rapid was the progress from the
introduction of the dental engine in 1871 up till now. At present
the field of tooth cutting techniques is still in a rapidly changing
state of flux. Uptill now there is no one instrument that has been
devised that will meet the requirement of each individual dentist.

REFERENCESREFERENCES
1. Philip’s science of dental materials
Skinner
2. The science & Art of dental ceramics
John W. Mc Lean
3. Restorative dentistry
Craig
4. Text book of dental materials
Sharmila Hussain
5. Q I. March 2001. Volume 32. Number 3
6. JPD. July 1999. Volume 82. Issue 1
7. Notes on dental materials
Wright

Rotary instruments / dental implant courses by Indian dental academy

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

En vedette

En vedette (7)

Similaire à Rotary instruments / dental implant courses by Indian dental academy

Similaire à Rotary instruments / dental implant courses by Indian dental academy (20)

Plus de Indian dental academy

Plus de Indian dental academy (20)

Dernier

Dernier (20)

Rotary instruments / dental implant courses by Indian dental academy