Instruments for tooth preparation

(enamel, dentin and carious dentin)

JÚLIA DR. NEMES

 Definition of the toothpreparation

 PREPARING THE TOOTH FOR FILLING

are called TOOTH (CAVITY) PREPARATION

-Instrument
-Knowledge, Rules
7. week 1-th MIDTERM 20 of March

Thursday 8:50-9:35

in this Room (I. Női Klinik)

after the Conservative lecture

Possibilities for preparation

 Hand instruments
 Rotary cutting instruments
 Oscillating instruments
 Laser
 Chemical-mechanical caries
removing
 Air abrasion
Hand Instruments G.V.Black classification
Nowdays hand instruments are not used for
primer preparation.

 Advantage: not caused iatrogen damage

 Disadvantage: very low effectivity

 Instruments for enamel preparation:

Chisel (Black)
Hatchet
Gingival margin trimmer *
 Instruments for dentin preparation:
Excavator (spoon*, hoes and hatchet)

Most of them are paired instruments!

Characterisation of the hand instruments
3 (or 4) data

 Width of the blade (in tenths of a millimeter

o,1 mm)
 Blade length (in mm)
 Blade angle (in clokwise centigrade)

Exception: Gingival margin trimmer 4 data!

Primary cutting edge angle
(in clockwise centigrades.)
 Gingival margin trimmer 4 data!
A Width of the blade
(in tenths of a
millimeter o,1 mm
8)
B Primary cutting
edge angle (80)
C Blade length (in
mm13)
D Blade angle: in
clockwise
centigrade
Paired instruments 14
Rotary (powered, driving) cutting equipment
(hand, foot, electric, turbina, micromotor, airmotor)

Foot engine 1871 Dental unit

 Rotary cutting instruments
DEVELOPMENT

 IN DRIVING (in equipments)

 IN CUTTING INSTRUMENTS (burs)

 Driving: hand
- foot engine 1871 Morrison (700 rpm)
- electric driving: elektric engine, mikromotor
- air driving: turbina, airmotor
 Turbine Micromotor
Handpiece (only contraangeled) Handpiece(straight, and contraangeled)
compressed air direct current (electric) or
compressed air (air motor)
Turbine Kuplung Hose
Micromotor
Wheels run on bearing

Handpiece Kuplung Hose Handpiece Micromotor Hose

Turbine (vheels are in the head of handpiese)
Vheels are in the head of cont-
raangle-handpiece.

When turbine is in operation,

some of the drive air flows into
the vheels and then into the
valve, opening the exhaust-air
passage.

Immediatly the turbine is

switched off, the valve seals
the exhaust-air, preventing the
aspiration of contaminated
aerosol.
 TURBINE
(1956)

 Speed:
-free running speed:
300-450.000 rpm Air-bearing
-speed for load: half 310.000 rpm
of the free running 2,5 bar
speed
 Direction of the running
can’t be changed!
 Speed for load: change
Ball-bearing

Air-bearing-, ball-bearing with ceramic

turbine (ceramik ball) balls
440.000 rpm
3,5-4 bar
 MICROMOTOR (1966)

 Electric micromotor:  Air-motor:

max. revolution: 40.000rpm max. revolution: 25.000rpm
 Direction of the running can  Direction of the running can
be changed! be changed!
 Speed for load is constant!  Speed for load is constant!
 Changing of the revolution in case of micromotor
(Akcelerator, Reductor )

Electric Air
motor motor
Blue ring 4.000-40.000 5.000-25.000
1:1
Red ring 20.000-200.000 25.000-
1:5 125.000

Green ring 800-8.000 1.000-5.000

5:1
7,4:1 Cooling:

2,8:1 - out or inner

Surgical and endodontical handpieces (Driving moment!)
 Handpieces:

 can be
straight handpiece
contra-angled handpiece
latch-type burs
friction grip (FG) type burs

Function of the handpieces

 holds the rotating instrument, and

 transportes the power for rotating
instrument.
 Rotary cutting instruments
burs, diamonds (abrasives)

Consist of: shank, neck and head.

Every (one) has his own function!

 Functions of the shank, neck and head
of rotary cutting instruments
 Shank: fits into the handpiece:
length, crosssection and the end-
shape can be different.
Shape: straight handpiece, latch
tip, and friction-grip tipe
contraangle handpiece Latch-
l tip

 Neck: transmit the rotational and friction-grip

translational forces to head. tipe
It has taper form, and the taper
can influence the visibility, the
access and the strength.

 Head: makes the preparation.

The shape and the material of the
head depends on the work
(enamel, dentin, or carious
dentin)
Head of the rotary cutting instruments

 Rotary cutting instruments: according to the

material of the head can be: diamond and metall
burs.

 Diamond: is an abrasive instrument, consist of

three parts.
The metal blank, that holds the diamond grits
and the bonding material. Size of the diamond
grits can be different.
 CONSTRUCTION of the diamond bur

- size of the diamond grit (color code)

- the bonding material

- Using diamond for preparation with grit size

>ISO 524 (cc. 45µm and surface roughness
>30 µm,) we always has to finish the
prepared surface!
Head of the rotary cutting instruments

 Metal (Bur): has bladed cutting edges.

Steel burs: cut the dentin at low speed well,

but not good for enamel preparation!

Carbide burs: perform better at all speeds.

It is possibility to use both into the enamel
and dentin!
 CONSTRUCTION of the metal bur

-number of the blades:The more are

the number of the blades, the
smoother is the prepared surface.
Blades:
bur: (4,6,8, 10) excavating bur
finishing bur (12, 16,18,30)
-direction of blades
straight or axial
spiral
Both can be manufactured
with or without crosscuts.
Shape of the burs and diamond

 Round
 Straight fissure
 Tapered fissure
 Pear-shaped
 (Inverted cone)
 Flame
 SIZE of the bur
 SIZE: The largest diameter of head in
1/10 mm.

-005 diameter : 0,5 mm

-010 „ 1,0 mm
-016 „ 1,6 mm
-023 „ 2,3 mm

The bigger is the diameter of the bur, the smaller

speed can we use, to achieve the suitable effect
(output).
Recommendation for instrument choice

 Speed
 Burs
the material
the shape
the size

 For Preparation/Finishing
Finishing and polishing the compositfilling
FINISHING POLISHING
AMALGAM FILLING
International standard for selection of burs
ISO 6360

A B-C D E F
FG end or
Latch-type end

 A: material of the head (3 figures)

 B: shank of the bur
C: overall length 3 figures
 D: shape of the bur (3 figures)
 E: construction of the bur (3 figures)
 F: size of the bur (3 figures)
Preparation for direct
restoration
Steps, instrument, speed

Primer preparation: turbine, micromotor (akcelerator) 170-

200.000 rpm
Material: diamond ISO 806
Shank and full length: FG end, normal ISO 314
Shape: pear, fissure round ISO 233,234, ….
Grained: middle (blue) ISO 524
Size: depends on.. ISO 008-014

Removing of caries: micromotor (blue) 4.500-6.000 rpm Latch

Material: steel, or hardmetal ISO 310, 500 type
Shank and full length: latch-type, normal ISO 204
Shape: round ISO 001direction!
Size: different ISO 008-014

Finishing: micromotor (akcelerator) 10.000-40.0000 rpm

Material: diamond, metal
Shank and full length: FG end
Shape: similar to be used in primer preparation
Construction:diamond: fine, ultra, extra fine grit (red, yellow
white)
hard metal: 16,18 cuttig edges
Primer preparation: Turbina, Mikromotor (akcelerator)170-
230.000
Diamond bur
Sekunder preparation: Caries removing Micromotor (blue)
Steel or hardmetall bur
 Removing of old filling

 Material:

amalgam: hard metall

(rubber dam or exhaustor)

komposit: hard metall or diamond

Primer preparation: Turbine, Micromotor (akcelerator)170-
230.000
hard metall bur
Sekunder preparation: Removing caries Micromotor (blue)
Steel or hard metall bur

FG
end
Caries excavation using a spoon-
shaped hand excavator
 (a) Original cavitated
mandibular molar,

 (b) carious dentinen with

peripheral sound dentine
exposed after enamel
removal,

 (c) infected dentine

excavated with hand
instrument, and

 (d) completed caries

excavation with
‘‘scratchy’’ sound dentine
remaining.