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Operative Dentistry > Operative > Flashcards

Operative Flashcards

1
Q

Operative Dent Definition

A

The science and art in dentistry that studies the prevention, diagnosis, treatment of defects in enamel and dentin

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2
Q

Carious vs. Non Carious

A

C

  • bacterial infection
  • diseased tissue has to be removed
  • precise Cavity preparation

NC
-loss of surface tooth structure due to mechanical or chemical factors
Exs) attrition, abrasion, erosion, abfraction

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3
Q

Direct Restoration vs Indirect Restoration

A

Direct-
Dental material placed in a soft state directly in a cavity preparation to restore contour before it sets hard

Indirect-
A restoration fabricated outside the oral cavity then cemented or bonded to the tooth
-generally sent to the lab to be made
-CADCAM tech

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4
Q

Rotary Speeds for Handpieces

A

Slow/Low Speed
-<12,000 rpm (less friction/heat generation)
-no water coolants
-less efficient, more controlled removal
-need to tell patient they will feel a lot of vibrations
-has interchangeable attachments
Uses:
-deep caries excavation in close proximity to the pulp to avoid pulp exposure
-cleaning external surface of teeth (coronal polishing)
-finishing or polishing procedures

Medium Speed

  • 12,000-20,000 rpm
  • infrequently used and not used at OSU

High Speed
->200,000 rpm
-generates a lot of heat so water coolants are needed
-most cutting efficiency–>less vibration and pressure leading to less patient discomfort
-attachments are not interchangeable like the slow speed
Uses:
-teeth preparations
-removal of old restorations

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5
Q

Delivery Tubing System

A

-4 hole connector line (most common)

  • large nut–> high speed
  • small nit –> slow speed
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6
Q

Coupler

A
  • attached the hand piece to the delivery unit and supplies air and water to the hand piece
  • the 4 hole line receives the handpiece coupler
  • fixed or moveable(360 swivel)
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7
Q

Slow Speed Parts

A
  • Slow Speed Motor
  • Nose cone/straight attachment (used for extra oral things like trimming casts or crowns)
    • long shank type bur/straight bur
  • Contra-angled Attachment (used for harder to reach places)
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8
Q

Slow Speed Heads

A

2-Latch type (RA) Head

  • accepts only latch end burs
  • latch end burs larger in diameters than friction grip burs
  • Swing latch; Push button Latch; Spring Latch

Friction grip head
-uses friction grip type bur (smaller diameter and shorter shanks that latch type)
-two mechanisms
A: friction generated from an internal spring assembly (push button)
B: a special tool using force to overcome and generate friction (bur tool type)

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9
Q

Components of Rotary Instruments

A

Head

  • the working part of the instrument
  • consist of either blades or abrasive particulate surfaces
  • many shapes and sizes

Shank

  • straight/long shank (nose cone)
  • latch design (slow speed contrangled latch type)
  • friction grip design (slow speed contrangle firction grip head and high speed)

Neck

  • not too bulky to avoid interfering with operator’s visibility
  • not too narrow to become a weak link between the head and the shank
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10
Q

Bladed Instruments

Composition of Bladed Instruments vs Diamond Instruments

A

-the greater number of blades the smoother the finish

  1. Excavating/ cutting burs (blades 6 or 8)
  2. Finishing burs (blades 10-20)
    • color coded: 10-12 (red); 16-20 (yellow); 30 (white)

Comp Bladed
-carbide for blade cutting
-blades…tungsten carbide blanks ground to the desired shape. Stronger and harder than stainless steel but brittle
-tungsten carbide head is attach to the steel bench and shank by welding and brazing
Uses: INTRAcoronal preps

Comp Diamond
-diamond for abrasive cutting
   -metal blank on which small diamond particles are held together within a softer matrix 
-color coded for degree of abrasiveness 
   -Yellow: superfine
   -Red: fine
   -Blue: medium
   -Green: coarse 
   -Black: supercoarse 
(We will use blue and green for crown preps)
Uses: EXTRAcoronal preps
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11
Q

Pear Shaped Bladed Head Design

A

Used for Intracoronal Preps

330

  • Length: 1.5mm
  • Taper: 8 degrees (inversion walls)
  • Diameter: 0.8mm

245

  • Length: 3mm
  • Taper: 4 degrees
  • Diameter: 0.8mm
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12
Q

Round Spherical Head Design

A

1/4 - 11

1/4 = 0.5mm

4(full) = 1.4mm

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13
Q

Plain Cylindrical Fissure Blade Head

A

-creates parallel walls
-55-59
(Designate 200 series for rounded corners)

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14
Q

Plain tapered fissure

A

We use 169

  • narrowing at the distal end of blade
  • creates divergent walls
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15
Q

End Cutting

A
  • designate a 900 (we use 956)
  • no side blades
  • used to smooth floor
  • end only carries the cutting blades
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16
Q

Mechanism of Cutting

Brittle vs Ductile Fracture

A

Brittle

  • brittle material fractures by crack formation upon tensile loading
  • enamel is brittle
  • abrasive cutting: more efficient with brittle materials (microcracks) –>extracoronal preps (diamond burs)
  • like dropping a plate

Ductile (will absorb more energy)

  • plastic deformation of the material by shearing
  • bladed cutting more efficient with ductile material (deform then shear)–> intracoronal preps in dentin
17
Q

Blade Design

Angles

A

Rake face

  • the surface that forms the chip
  • the surface of the blade towards the direction of cutting (usually clockwise)

Clearance face

  • surface the clears the chips
  • away from the direction of cutting

ANGLES (look at pic on slide 43, lecture 1)

Edge angle
-between the rake and the clearance surfaces
Rake angle
-between the radial line and the rake face
Clearance angle
-the angle that provides clearance between the cutting edge and the tooth structure

18
Q

Positive Rake Angle

A
  • sharper than the negative
  • when the radius (from cutting edge to axis of bur) is ahead of the rake face
  • higher cutting efficiency
  • larger chips produced
  • chip space smaller; clogging of chip space
  • always a chance to curve, fracture material if not adequate
  • break easily
19
Q

Negative Rake Angle

A
  • when the rake face is ahead of the radius (from the cutting edge to axis of bur)
  • decreased cutting efficiency
  • smaller chips are produced= no clogging of the chip space
  • cutting edge is spared (less liable to fracture) since carbide burs are brittle)
20
Q

Clearance Angle

A
  • the angle that provides the clearance
  • prevents the blade from rubbing on the tooth surface
  • bigger the clearance angle –> less friction –> dulling minimized –> bur life lengthened
21
Q

Hand Instruments

A
  • Examination Instruments
  • Hand cutting instruments
  • Restorative instruments
  • Accessory instruments
22
Q

Examination Instruments

A

Mirror

  • non dominant hand
  • reflects light
  • for indirect vision
  • retracts lips, cheeks and tongue for access
  • protection of soft tissue: tongue, floor of the mouth

Explorer (Sheperd’s hook #23, Pigtail/cowhorn #2)
-pointed tip to enhance tactile sensation for caries detection

Periodontal Probe

  • measures cavity depth
  • “dental ruler”
23
Q

Shank Design Principles

A
  • balance
  • concentration of the force onto the blade without rotation of the instrument
  • out of balance: creates more torque
  • balanced: concentrates forces on cutting edge
24
Q

Black’s Instrument Formula

3 Unit Formula

A

1st Number - width of the blade in tenth of a mm (ex-10=1mm)
2nd number - length of blade in mm (ex- 7 =7mm)
3rd number - angulation of the blade to the long axis of the handle
-expressed in 100th of a circle
-always <50

25
Q

Black’s Instrument Formula

Four Number Formula

A

The second number indicates the primary cutting edge relative to the long axis of handle (always greater than 50

1st- Width of blade
2nd (new)- primary cutting edge angle (>50)
3rd- blade length in mm
4th- blade angle relative to the long axis in centigrade

26
Q

Restorative Instruments

A
  • insert and carve the restorative material
  • carrier
  • condenser/plugger
  • anatomical/acorn burnisher
27
Q

Accessory Instruments

A
  • articulating paper holder (miller forceps)
  • scissors

-Amalgam well (accessory equipment)

28
Q

Direct Cutting

A

-force is applied to perpendicular to cutting edge
-hold the instrument parallel to the wall planed at all time
-the cutting edge in contact with the wall being planed
Ex) enamel hatchet

29
Q

Lateral Cutting

A

-indirect cutting/ lateral cutting/ scrapping: force is exerted is parallel to the cutting edge
-motion: from the beveled to the non beveled side (away from the bevel)
Ex) Enamel Hatchet and Gingival Margin Trimmer

30
Q

Enamel Hatchet

A
  • the cutting edge is parallel to the long axis of the handle
  • direct and lateral cutting
  • double ended instrument with right and left bevels
31
Q

Chisel Family

A

A. Straight/ slightly curved/bin angled chisels (push motion)
B. Enamel Hatchet: direct cutting and lateral cutting
C. Gingival Margin Trimmer: lateral cutting

32
Q

Gingival Margin Trimmer

A
  • 4 unit formula
  • the blade is curved and not milled in a single plane: curved blade accentuates the lateral cutting
  • cutting edge makes an angle to the long axis of the blade
  • lateral cutting: force is applied parallel to the cutting edge
33
Q

Excavator Family

A

A. Ordinary hatchet
B. Hoes (pull)
C. Angle Former
D. Spoon

Operative Dentistry (2 decks)

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