Drilling and Instruments Flashcards
Dental material used to restore back function and morphology of the missing part of the tooth structure
Restoration
Dental material placed in a soft state directly in cavity preparation to restore contour before it sets hard
Direct restoration
A restoration fabricated outside the oral cavity then cemented or bonded to the tooth
Indirect restoration
Two types of handpieces
1-Air driven
2-Electric
Mainstay handpiece for cutting teeth
Air driven
Quieter handpick that cuts with higher torque, higher power and less stalling
Electric
- <12,000rpm
- no water coolants
- less efficient, more controlled removal
- uses = controlled removal near pulp, coronal polishing, and finishing and polishing procedures
Slow Speed Handpiece
12,000-20,000rpm
Medium speed Handpiece
- > 200,000 rpm
- generates considerable amount of heat (needs water coolants)
- most cutting efficiency (less vibration and discomfort)
- uses = teeth prep and removal of old restorations
High Speed Handpiece
4 parts of a handpiece
head, attachment, shaft, and coupler
Part of handpiece that attaches the handpiece to the delivery unit and supplies air and water to it
coupler
What is the type of bur a straight handpiece uses, and what procedures is a straight handpiece used for?
long shank type burs/straight burs; extra oral procedures (e.g. finishing a crown)
______ and ______ heads can attach to a contrangled slow speed head
latch type and friction grip
Latch type (RA) heads accept only ________ burs, which are _____________ than the friction grip burs
latch end, larger in diameter
Friction grip burs have ______ diameter and ________ shanks than latch type
smaller, shorter
Types of friction grip heads
- push button
2. bur tool type
Friction generated from internal spring assembly is used to hold the bur
push button head
A special tool using force to overcome and generate friction is used to hold the bur
bur tool type head
Three types of rotary instruments
- bladed instruments
- DIamond (abrasive instruments)
- Other abrasives
Number of blades on excavating/cutting burs vs. finishing burs
6-8 on cutting burs, 10-20 on finishing burs
How does number of blades affect the finish?
More blades, smoother finish
Color coding system for finishing burs
Red = 10-12
Yellow - 16-20
White = 30
Carbide blades – reason for that material and uses
reason = carbide stronger and harder than stainless steel uses = intracoronal preps
Metal blank on which small diamond particles are held together within a softer matrix
Diamond instruments
Uses for diamond instruments
Extracoronal preps
Shank colors for diamond instruments in order of ascending degree of grit
yellow (superfine), red, blue, green, black (super coarse)
Types of “other abrasives”
Coated or molded
Purpose of coated abrasives
abrasives on flexible backing to finish restorations
Molded abrasives can be used for _______ and _______ if rigid or ________ and ______ if flexible
Grinding and shaping if rigid
Finishing and polishing if flexible
Abrasives that can be mounted or unmounted and rigid or flexible
Molded abrasives
Round, inverted cone, pear shaped, plain cylindrical fissure, and plain tapered fissure are the designs of what?
Designs of bur heads
Numbers associated with round burs
1/4 - 11 (starts at 0.5mm and diameter increases)
Numbers associated with inverted cone burs
331/2-40
Pear shaped bur numbers
229-333
330 bur length, taper, and diameter
l = 1.5 mm taper = 8 degrees d = 0.8mm
245 bur length, taper, and diameter
l = 3.0 mm taper = 4 degrees d= 0.8mm
Plain cylindrical fissures numbers
55-59 or 200 series for rounded corners
Plain tapered fissure
169-172
Designation for end cutting (when only end has blades)
900 (e.g. 956)
Cross cut bur designation
500 before bur number, also a 700 version
Fracture caused by crack formation upon tensile loading; the type of fracture that occurs in enamel
Brittle fracture
What type of cutting is most efficient with brittle materials?
Abrasive cutting
Fracture caused by plastic deformation of the material by shearing
Ductile fracture
What type of cutting is most efficient with ductile material?
Bladed cutting
What kind of fracture do teeth undergo?
Both - brittle and ductile
What kind of burs perform abrasive cutting?
Diamond burs
How does bladed cutting work? What is it recommended for?
Cuts by shearing layers of tooth structure
Recommended for intracoronal preparations
Rake face
Surface that forms chip, is the surface of the blade toward direction of cutting
Clearance face
Surface that clears away the chips, is away from the direction of cutting
Edge angle
between rake and clearance angles
Rake angle
between radial line and rake face
Clearance angle
angle that provides clearance between the cutting edge and tooth structure
The angle to describe when the radius (from cutting edge to axis of bur) is ahead of the rake face
Positive rake angle
also assoc’d with higher cutting efficiency, larger chips, smaller chip space, chip clogging, and fracture
Match the following to the correct rake angle:
- higher cutting efficiency
- smaller chips
- larger chip space
- clogging of chip space
- higher cutting efficiency = positive rake angle
- smaller chips = negative rake angle
- larger chip space = negative rake angle
- clogging of chip space = positive
The angle to describe when the rake face is ahead of the radius (from cutting edge to axis of bur).
Negative rake angle
(also assoc’d with decreased cutting efficiency, smaller chips, no chip clogging, and sparing of cutting edge preventing fracture)
Prevents blade from rubbing the tooth surface. The larger this angle, the less friction and bur dulling.
Clearance angle
Name the four types of hand instruments and an example of each
examination instruments (non cutting) - explorer
hand cutting instruments - hatchet
restorative instruments (non cutting) - condenser
accessory instruments - Miller forceps
What is the blade and handle made of in hand cutting instruments?
Blade = carbon steel (harder than stainless steel)
Handle = stainless steel (corrosion resistant and retains shine0
Shank design must insure ______ to concentrate the force onto the blade without rotating the instrument
Balance
Black’s instrument formula (general)
3 or 4 unit code used to describe a cutting instrument
Define each number of Black’s basic instrument formula
1st number = width of the blade in tenth of a mm (10=1mm)
2nd number = length of blade in mm
3rd number = angulation of the blade to the long axis of the handle, expressed in 100ths of a circle and always <50
Define each number of Black’s 4 number formula
1st = width of blade in tenth of mm 2nd = primary cutting edge angle (>50) 3rd = blade length in mm 4th = blade angle relative to long axis
In what direction is force applied when using direct cutting, and how is the instrument held agains the wall being planed?
Force is applied perpendicular to cutting edge. Instrument is held parallel to wall being planed to keep the cutting edge in contact with the wall.
In what direction is force applied when using indirect/lateral cutting, and how is the instrument held agains the wall being planed?
Force is exerted parallel to cutting edge. The instrument is moved from away from the beveled side.
Three types of chisels and their purpose
- Straight/ slightly curved/bin angled chisels (push motion)
- Enamel Hatchet: direct cutting and lateral cutting
- Gingival marginal trimmer: lateral cutting
The cutting edge is ______ to the long axis of the handle of an enamel hatchet
parallel
In a ___________ the blade is curved and not milled in a single plane. This accentuates ________ cutting.
Gingival marginal trimmer, lateral
Ordinary hatchets, hoes (pull), angle formers, and spoons
Types of instruments in the excavator family
