Operative lecture 1 Flashcards
Enamel, Dentin, Pulp characteristics
Enamel: Very brittle
Dentin: more ductile, deforms before it breaks after pressure.
Pulp: Connective tissue
Carious vs. Non carious
Carious: Bacterial infection, diseased tissue has to be removed, precise cavity prep needed.
Non-carious: loss of surface tooth structure due to mechanical or chemical factors..
Example: Attrition, abrasion, erosion, abfraction –> all chemical loss of tooth surface.
Direct restoration (give example) vs. Indirect restoration
Direct: Dental material placed in soft state directly in cavity prep to restore contour before it sets hard. (algams, composite)
Indirect: Restoration fabricated outside oral cavity and then cemented or bonded to the tooth.
2-medium speed?
3-high speed?
- Slow speed?
12,000-20,000rpm
> 200,000 rpm (removes older restorations, cavity prep)
most common connector line?
4 hole
High speed handpiece
fixed coupler, and head
Slow speed handpiece
Contra angled attachment –> intra oral procedures
Straight attachment –> always used for extra oral proecdures (smooth crown finish/polish)
3- friction grip head
uses friction grip type bur (shorter shanks than latch type)
2-latch type head
accepts only latch end burs
latch end burs are larger in diameter than the friction grip burs
What direction to attach bur on bur tool type/bur changing wrench?
Clockwise to attach bur
Rotary cutting instruments:
head
stainless steal
Rotary cutting instruments:
Shank
straight/long
slow speed contragled latch type
friction grip design
Larger diameter
Rotary instruments–Bladed instruments (burs)
- excavating
2. finishing
1-carbride for blade cutting (bladed instruments)
- blades..tungsten carbrdie blanks ground to the desired shape. Harder/stronger than stainless steal but BRITTLE
- Uses: Intracoronal prep (going through enamel/dent shovel into tooth
Other abrasives (Non cutting-Not diamond)
Coated
discs attached to handpieces for finishing restorations
Other abrasives (Non cutting-Not diamond)
Molded
Mounted (points and stones) vs. uncmounted (cutting discs and stonewheels)
Rigid (grinding and shaping) or flexible (finishing and polishing)
Bladed instruments:
- Excavating/cutting burs
- Finishing burs
- The greater the number of blades?
- blades 6 or 8
- 10-20 (above 8)
- color coded 10-12 red
- 16-20 yellow
- 30 white - the smoother the finish
Diamond instruments:
2- Diamond for abrasive cutting:
Used for extra coronal prep
shank color coded for degree of abrasiveness yellow: superfine red: fine Blue: med Green: coarse Black: Super coarse
The abrading surface –> used for crown preps
Bladed head design:
- Round 1/4 vs. 4
- Inverted Cone
- Pear shaped
- Plain cylindrical fissure 55-59
- Plain tapered fissure 169-172
- 0.5mm vs. 1.4
- 331-2-40:: Connical shape with flat ended bur
- 229-333:: 330–diameter is 0.8 with a length of 1.5 (this is wider distally) with 8 degree taper vs. 245 with 3.0 mm length and diameter of 0.8 (twice the size of a 330) with 4 degree taper
- paralalalal wall 57 bur with diameter of 1mm with flat end.
- diversion wall (with 171 we have distal end narrow and proxmial wider)
bladed cutting recommended for what kind of preps?
intracoronal (bc into tooth aka into enaml –> dentin
end cutting designate what number?`
900 (end only carries the cutting blades aka 956 that you use to flatten your surface)
Cross cut designate what number?
- Also 700
Abrasive cutting mechanism and what kind of burs?
Diamond bur– more efficient with brittle materials but NO BUENO with ductile material (dentin bc it deforms) …plastic deformations
Rake face blade vs. Clearance face blade
rake face: forms the chips, the surface of the blade towards the direction of the cutting
Clearance face: clears the chips. Away from direction of cutting
