Op 1 Flashcards
What is the 4 number instrument formula used for?
margin trimmers
What do these numbers represent: 15-98-10-14?
15 = 1.5mm width
98 = angle of cutting edge to long axis of handle
10 = 10mm blade length
14 = angle of blade to long axis of handle
What are 3 functions of hand instruments?
Removes loose enamel
Smooths preparation
Refines cavity features
What are 2 examples of refining cavity features?
Retention areas
Line angles
What are the 2 metals in hand instruments?
Stainless steel
Carbon steel
What are the features of stainless steel?
Resists corrosion
Dulls easily (need to keep instruments sharp)
What are the features of carbon steel?
Corrodes
Holds sharpness
What are the 3 types of hand instruments?
Hand cutting instruments
Restorative instruments
Plastic instruments
What are the hand cutting instruments (examples)?
chisels, hatchets, hoes, gingival margin trimmers, excavators, carvers
What is the most common excavator used?
spoon
Characteristics of chisels
Straight or curved
1, 2, or 3 angles
Characteristics of hatchets
Cutting edge = in plane parallel with handle
1 or more angles
Do not use with too much force or twist (can easily break)
Characteristics of hoes
Cutting edge is ⟂ to handle
Characteristics of gingival margin trimmer
Similar to hatchet, but has curved blades
Cutting edge is at angle to length of blade
Characteristics of excavators
Remove caries
Characteristics of carvers
Place anatomy
What are restorative instruments used for?
Used to place, condense, and carve restorative materials back to normal anatomy of teeth
What are restorative instruments primarily made of?
Stainless steel
What are the restorative instruments (examples)?
amalgam carrier, condensers, burnishers, carvers, amalgam knife, composite placement instruments
Characteristics of condensers (aka amalgam plugger)
Condenses materials
Can be used to gauge cavity width
Characteristics of plastic instruments
Can be used to carry pliable restorative material to prepped cavity (although typically placed directly by composite gun)
Used to shape material
What are the 3 parts of hand instruments?
Shaft/handle
Shank
Blade
Characteristics of shaft/handle of a hand instrument
Can be small, medium, large
Smooth or serrated
Characteristics of shank of a hand instrument
Connects handle to blade
Straight or angled
(Angled for access and stability)
Characteristics of blade of a hand instrument
Working part of the instrument
Beveled to create cutting edge
How many bevels can the blade of a hand instrument have?
3
Where is the primary cutting edge of the blade of a hand instrument?
on the end
Where is the secondary cutting edge of the blade of a hand instrument?
on the sides
Can hand instruments be double ended? Or just single ended?
They can be double ended (2 working sides) or a long handle with 1 working side
What are the 3 categories for sterilization?
Critical
Semi-critical
Non-critical
What does critical mean in regards to sterilization? Give an example
Penetrates soft tissue of bone
Ex: forceps
How do we sterilize critical instruments?
Autoclave (most commonly used heat sterilizer in dentistry)
What does semi-critical mean in regards to sterilization? Give an example
Does not penetrate, but contacts mucous membranes or non-intact skin
Ex: mirrors
How do we sterilize semi-critical instruments?
Autoclave or high level EPA sterilant/disinfectant
What does non-critical mean in regards to sterilization? Give an example
Comes in contact only with intact skin
Ex: blood pressure cuff
How do we sterilize non-critical instruments?
Intermediate or low level disinfectant
How many classes of carious lesions are there? Which one is most and least prevalent?
6 (I-VI)
Most prevalent = Class I
Least prevalent = Class VI
Where are caries on Class I lesions?
Pits and fissures on:
-Occlusal ⅓ of molars and premolars
-Occlusal ⅔ of B & L surfaces of molars and premolars
-L surface of upper anterior teeth
-Any other unusually located pit or fissure
What is the general rule of pit/fissure lesions? (Class I)
More constricted at enamel surface and wider toward DEJ
Where are caries on Class II lesions?
Caries affecting proximal surfaces:
-Molars and premolars
What is the general rule of smooth surface interproximal lesions? (Class II)
Wider at enamel surface
Where are caries on Class III lesions?
Caries affecting proximal surfaces of:
-Central and lateral incisors
-Cuspids without involving incisal angles
Where are caries on Class IV lesions?
Caries affecting proximal surfaces including incisal angles of anterior teeth
Where are caries on Class V lesions?
Caries affecting gingival ⅓ of facial or lingual surfaces of:
-Anterior teeth
-Posterior teeth
Where are caries on Class VI lesions?
Caries affecting cusp tips of:
-Molars
-Premolars
-Cuspids
What is abrasion?
Tooth surface loss from frictional forces
What is erosion?
Tooth surface loss from chemico-mechanical action
What is attrition?
Mechanical wear from opposition teeth (grinding)
What is abfraction?
Cervical, wedge-shaped defects as result of strong eccentric occlusal forces
What is fracture?
Can be most difficult and challenging defects in teeth to diagnose and treat
Can be considered incomplete or complete; involving pulp or not involving pulp
What are the 4 stages of caries progression?
Demineralization
Cavitation
Infected dentin
Affected dentin
What is demineralization?
Loss of mineral from tooth structure, resulting from a chemical process (can be from caries, acid, diet, or gastric)
What is cavitation?
Breakdown of surface integrity that can be detected using optical or tactile methods
Where can cavitation go?
Can be confined to enamel or extend into dentin via tubular invasion
What can cavitation include?
Differing layers of infected and affected dentin
How do caries penetrate (shape)?
Penetrate in a narrow or cone shaped channel to DEJ then spread laterally
What is infected dentin?
Irreversible, demineralized, and denatured layer with bacterial invasion
Very soft, moist, and easy to remove with spoon excavator
What is affected dentin?
Partially demineralized
Leathery/softer than normal
Collagen is not denatured
Contains minimal to no bacteria
What are the forms of tooth prep?
Outline
Convenience
Resistance
Retention
What is the outline form?
External shape of the prep
What do we consider when it comes to outline form?
Access to lesion
Extent of lesion
Restorative material being used
Esthetics
Function
What does access to lesion refer to in regards to outline form?
Visualize extent of caries
Allows bur to reach all carious dentin
Creates space for instrumentation and vision
You should extend your outline to include all ________ enamel, because enamel rods must be supported by _______ ___.
You also should include the ____ spread of caries at ____. Carious dentin can have ____ overlying dentin; ____ enamel is usually removed.
________ enamel can be considered for ____.
Unsupported; sound dentin
Lateral; DEJ; sound; undermined
Decalcified; inclusion
What determines the size of the prep?
Extent of caries in dentin
You should design your prep to take advantage of/compensate for what?
For properties of material to be used
What do brittle materials like amalgam and porcelain require when creating the outline form?
90° cavosurface margin
What do ductile materials like composite and gold require when creating the outline form?
Beveling of margin
What do esthetics refer to in regards to outline form?
Restorations in visible areas of mouth dictate cavity design and restoration selection
What does function refer to in regards to outline form?
When a restoration alters occlusion, outline may need to be altered
Do not leave occlusal contact on margin of restoration EVER
What is the convenience form?
Shape that allows access for the procedure to be done
Allows vision, access, and ease of instrumentation and insertion of restorative materials (influences outline form too)
What is the resistance form?
Shape given to prevent fracture of either the restoration or the tooth
What are examples of resistance form?
Adequate bulk of amalgam
Rounding of internal line angles
Horizontal pulpal and gingival floors prepared ⟂ to tooth’s long axis
What is the consideration of resistance form? What are the 3 reasons?
Prep is placed 0.5mm into dentin (not including enamel) for 3 reasons:
Avoid sensitive DEJ
Provide adequate bulk of restorative material
Take advantage of dentin’s resilience
What is the retention form?
Shape that prevents restoration from being displaced by tipping/lifting forces
What does retention form include?
Undercuts, truncation, grooves, pits, dovetails, etc.
What are the considerations of retention form?
Primary and secondary retention
How do we get primary retention?
Converging walls
(and sometimes dovetail)
How do we get secondary retention?
Grooves, coves, extensions, skirts, beveled margins, pins, slots, steps, amalgam pins, etchants, adhesives
(sometimes dovetail)
What does secondary retention do?
Helps retain restoration in case primary retention fails
Which type of retention do we always need?
Must ALWAYS have primary retention; secondary retention is needed when indicated
Features that enhance _________ form also enhance _________ form
retention; resistance
What is an external wall?
Touches uncut surface/cavosurface margin
What is an internal wall?
Does NOT touch uncut surface/cavosurface margin
What is a bur?
Rotary cutting instrument with bladed cutting head
What are most burs made up of?
Carbide head to steel neck
Describe carbide
Stiffer/stronger than steel
Holds up better at high speeds
Less prone to dull
Describe steel
Decreased cost of fabrication
Freedom in design
What does the arbitrary 2 part numeral code of burs indicate?
Size and shape
What are the basic shapes of burs?
Round
Inverted cone
Pear
Straight fissure
Tapered fissure
Features of round burs
Initial entry into tooth
Expansion of prep
Retention features
Caries removal
Features of inverted cone burs
Rapidly tapered cone with apex of cone directed TOWARD shank
Head length = head diameter
Undercuts in tooth prep
Features of pear burs
Slightly tapered cone with small end of cone directed TOWARD shank
245 = elongated pear bur for amalgam preps
330 = small version of 245
Feature of straight fissure bur
Elongated cylinder
Features of tapered fissure bur
Slightly tapered cone with small end of cone directed AWAY from shank
Used for indirect restorations
What are the 3 parts of a bur?
Shank
Head
Neck
What does a shank of a bur do?
Fits into handpiece
Accepts rotary mutation from handpiece
Provides bearing surface to control alignment and concentricity of instrument
How many classes of bur shanks are there? How many are important to us?
5 total classes; 3 are important to us
What are the 3 classes of bur shanks that we care about?
Straight
Right angle latch
Friction grip
What are straight bur shanks for?
Rarely used for prepping teeth
Used for oral surgery and polishing indirect restorations
What are right angle latch bur shanks used for?
Used in slow speed handpieces
Fits into D-shaped socket at bottom of bur tube instead of a chuck
What are friction grip bur shanks used for?
Used in high speed handpieces
Small size allows for improved access with molars
Held in place using friction between shank and chuck within handpiece
What is the neck of a bur?
Intermediate portion that connects the head to the shank
What is the function of the neck of a bur?
Transmits rotational and translational forces
How does the neck of a bur taper?
Tapers from shank diameter to smaller size by the head (improves access/visibility)
What is the head of a bur?
The working part of the bur
What does the head of the bur have?
Cutting edges/points that perform desired shaping of tooth structure
What part of the bur has the greatest area of variability based on intended application and technique?
Head
What is the primary retention feature for an amalgam restoration?
Converging B and L walls
What is the secondary retention feature for an amalgam restoration?
Retention grooves and dovetails
What must be included in the Class I prep outline form?
All caries and defective pits/fissures
In Class I preps, you should prep _____mm into _____ and _____ grooves to create nicely shaped dovetails in _______ and ______ ______ by also going slightly toward B and L (outline form)
0.5
B
L
M
D
Fossa
What is the retentive feature in Class I preps?
Dovetails
If the dovetail includes B and L grooves, is it considered primary or secondary retention?
Primary
If the dovetail is not part of the initial prep design, but instead is part of the extension feature, is it considered primary or secondary retention?
Secondary
What should be preserved unless undermined or crossed by a fissure in Class I preps?
Oblique and transverse ridges
Why do we direct the bur around cusps in Class I preps?
To conserve tooth structure
Remember we want:
No sharp angles
Gently flowing curves and distinct cavosurface margins (outline form)
What is the width in Class I preps?
1/5 to 1/4 (1.0 mm) of intercuspal distance
Why is the width of Class I preps 1/5 to 1/4 (1.0 mm) of intercuspal distance?
Conserves tooth structure
Facilitates carving for amalgam restorations
Reduces occlusal interferences
How should you center Class I preps?
On central groove (outline form)
What should the B to L width be in Class I preps?
No more than 1.0 - 1.5 mm (outline form)
What size should marginal ridges be in Class I preps?
1.5 mm (outline form)
How should the pulpal floor look in Class I preps?
Pulpal floor is flat and ⟂ to long axis of tooth (resistance form)
Why should the pulpal floor be flat and ⟂ to long axis of tooth (resistance form) in Class I preps?
At right angle to direction of occlusal forces
Helps resist fracturing/shearing forces
What is an isthmus? How is it created?
Narrow anatomic part/passage connecting 2 larger structures
Created by preparing occlusal width/outline
What does the isthmus of a Class I prep contribute to?
Retention and resistance form
Where is the isthmus of a Class I prep?
Central portion of prep between M and D-most aspects/dovetails
Where is the isthmus of a Class II prep?
Between 2 proximal flares or 1 proximal flare and dovetail
How deep should the pulpal floor be in Class I preps?
At least 1.5mm (resistance form)
The pulpal floor depth of 1.5mm resists ________ force to prevent _________. It also avoids sensitivity at the _______.
Occlusal; fracturing; DEJ
What angle should all cavosurfaces be at in Class I preps?
90 degrees
How should all line and point angles look in Class I preps?
Rounded, but defined, to avoid stress concentrations (resistance form)
How should B and L walls look in Class I preps?
B and L walls should converge pulpo-occlusally (retention form)
Converging B and L walls create an ____ angle with the ____ floor. This provides ____ retention. The degree of convergence should be ____ degrees.
Acute; pulpal; primary; 6
How should M and D walls look in Class I preps?
M and D walls should diverge pulpo-occlusally (resistance form)
Diverging M and D walls create an ____ angle with the ____ floor. This prevents undermining of the _____ _____.
Obtuse; pulpal; marginal ridge
Once you start carving, you _________ add to amalgam
CANNOT
If you have a void, fracture, or under-contoured area, you must drill out all amalgam in ________
Clinic
If you have a void, fracture, or under-contoured area, you must start a new tooth in _________
Lab
What are the causes for amalgam restoration failure?
What are the instruments used for amalgam occlusal anatomy?
- condenser
- egg burnisher
- acorn burnisher
- cleoid/discoid
- refine with acorn burnisher
What is the condenser used for when placing occlusal anatomy in amalgam?
Condenses amalgam into cavity
What is the egg burnisher used for when placing occlusal anatomy in amalgam?
Pre-burnishes amalgam, further condenses, and aids marginal adaptation
What is the acorn burnisher used for when placing occlusal anatomy in amalgam?
Places initial anatomy
What is the cleoid/discoid used for when placing occlusal anatomy in amalgam?
Carves and removes excess amalgam
What is the acorn burnisher used for when REFINING occlusal anatomy in amalgam?
Refines anatomy, improves smoothness, produces a satin (not shiny appearance)
Groove pattern can shine, BUT NOT the entire restoration
What are the 3 P’s of preventing injury?
Postural awareness
Positioning strategies
Periodic stretching and exercise
What does postural awareness consist of?
Neutral posture
Increases comfort and productivity
Decreases tension, numbness/tingling, joint discomfort, muscular problems, circulatory problems
Conserves energy
What do positioning strategies consist of?
Patient, dentist, lighting, OP setup
What does periodic stretching and exercise do?
Reduce fatigue, relieve stress, and increase stamina
Definition of musculoskeletal disorders
Soft-tissue injuries caused by sudden or sustained exposure to repetitive motion, force, vibration, and awkward positions
What can musculoskeletal disorders affect?
Muscles, nerves, tendons, joints and cartilage in your limbs, neck, and lower back
Advantages/disadvantages of lathe-cut alloy
High “positive pack” handling quality (“crunchy”) to provide good proximal contacts
Relatively > mercury required
Require early condensation with a small condenser
Irregular in shape, so higher packing forces needed during condensation
Minimal material-related post op sensitivity
Advantages/disadvantages of spherical alloy
Lower condensation pressure require to achieve same strength
Larger condenser required
Shorter working time, fast set, and high early strength
No positive pack because they move away from the condenser when packing (tendency to poor contacts and more overhangs because they can slide under the matrix band)
Greater risk of post op sensitivity
Advantage: you could work on the tooth the same day after restoring it with this type of amalgam
Advantages/disadvantages of admixed alloy (lathe-cut + spherical combined)
This is the type of amalgam we have!
Combine best of both geometries
High packing pressure with small condensers still required
Positive interproximal contact obtained
Slightly faster setting
Low post op sensitivity
Overall disadvantages of alloy
Not esthetic
Low tensile strength in thin sections under masticatory forces
It does not bond to tooth structure
Utilizes mercury
What is dental amalgam?
Metallic restorative material composed of a mixture of silver-tin alloy and mercury
What does the FDA say results from removing intact amalgam fillings?
Unnecessary loss of healthy tooth structure and a temporary increase in exposure due to additional mercury vapor released during the removal process
Has mercury in amalgam been found safe and beneficial as a direct restorative material?
Yes
Amalgam is _______ as a _____ lasting restorative material. It is ______ resistant to ______ caries as compared to bonded composite restorations.
Successful; long
More; recurrent
Amalgam is ______ for _______ restorations and when subsequent addressing of _______ health is needed before a definitive retoration
Ideal; large; pulpal
Amalgam is used as a __________ for badly broken down teeth that need extra ________ and __________ forms in anticipation of crown placement
Foundation/core; retention; resistance
Amalgam has ______ mechanical properties such as ________ ________, ________, and _________ __________.
High; compressive strength; rigidity; wear resistance
Amalgam has packable insertion to provide ________ proximal contact and intimate cavity adaptation
Positive
Amalgam is carvable with _______ instruments after insertion to provide optimal _______, __________, and _________.
Hand; contour; surface; occlusion
Amalgam has _____ ______ properties over time.
Self sealing
Purpose of reverse S curve
Preserve the cusp and and triangular ridge; forms a 90 degree cavosurface margin that creates a place of limited undermined enamel
Where are Class II carious lesions found in relation to contact point?
Located just apical to contact point
What is the purpose and functions of matrix bands?
For class II, matrix band replaces the missing proximal wall
Why does the wedge slightly separate teeth?
To compensate for the thickness of the matrix band
What does the wedge protect?
Gingival tissue/rubber dam during prep
What does the wedge seal?
Seals matrix against gingival floor to avoid overhang of amalgam
What does the outer nut of the Tofflemire matrix retainer do?
Locks matrix band into retainer
What does the inner nut of the Tofflemire matrix retainer do?
Adjusts size of matrix band
What does the slotted guide of the Tofflemire matrix retainer do?
Holds the matrix band in place
The Tofflemire matrix retainer should be _______ to the arch
parallel
What is self assessment?
Learning process
More than recalling info
Assists in making individuals more aware/responsible of their own learning
When does self assessment occur?
What is the sequence of use when polishing amalgam restorations?
1.Brownie polisher = achieves smooth surface (pre-polish)
- Greenie polisher = creates lustrous polish
- Supergreenie polisher = creates high polish
What does finishing a restoration mean?
Process of removing surface defects/scratches created during contouring process through use of cutting or grinding instruments (or both)
What does polishing a restoration mean?
Most refined of the finishing processes; removes finest surface particle
Production of shiny mirror like surface, which reflects light similar to enamel
How do you cause mercury to rise to the surface of an amalgam restoration?
During polishing, heat is created
Heat brings mercury to the surface of the restoration, which results in a dull, cloudy surface, and a surface that is more susceptible to corrosion
How long should you wait before finishing and polishing amalgam restorations?
At least 24 hours after it has been placed and carved
What is required for the development of caries?
Primary modifying factors (like tooth anatomy, saliva, pH) + secondary modifying factors (education, socio-economic status, age) + host + cariogenic biofilm + time + fermentable carbohydrates = caries
What bacteria is responsible for caries formation?
Streptococcus mutans
