Operative Part 2 Flashcards
What is a GV black class 6 classification?
Just incisal edge of anterior or cusp tip of posterior
What is friable enamel?
Enamel that is hypomineralized. Not only is it weaker, Bonding agent is not as effective in friable enamel.
Ideally, cavosurface margins should be > or = to ___ degrees
90
A cutting bur is likely to have ___ blades while a finishing bur is likely to have ___ blades
6
12
You have to lose about __% of enamel mineral before you can see a radiolucency.
25%
In other words, the actual disease is 25% worse than it appears on an X-ray
Define dental ferrule
A band that encircles the external dimension of tooth structure
What is the minimum ferrule length when restoring a root filled maxillary central incisor with a post and core retained crown?
1.5mm
True or false… ferrule refers to the step-like feature on a tooth for a crown
False.. ferrule refers to the portion of the crown that touches the axial walls of the tooth
What comprises the biological width?
1mm connective tissue attachment
1mm epithelial attachment
1 + 1 = 2mm biological width
It is generally safe to place crown margins __ subgingival without impinging on the biological width
0.5mm (AKA there needs to be 2.5mm from crest of bone to crown margin at minimum)
What are two methods to prepare a tooth for a crown that would otherwise impinge on the biological width?
Crown lengthening (bone down)
Orthodontic extrusion (tooth up)
Name two different types of chemicals used for external bleaching
Hydrogen peroxide
Carbamide peroxide
What are the differences between hydrogen peroxide and carbamide peroxide?
Hydrogen peroxide - breaks down faster (30-60 minutes)
Carbamide peroxide - remains active longer (2-6 hours), increased shelf life
For every 10% of carbamide it forms about ___% of hydrogen peroxide. In other words, its a __:___ ratio
3
1:3
True or false… there is no difference in sensitivity, rebound/regression, and results between hydrogen peroxide and carbamide peroxide
True
What percent of hydrogen peroxide is used for in-office visits only?
30-40%
What are some risks of external bleaching?
Gingival irritation
May worsen tooth sensitivity (reversible)
Will not change the color of fillings and crowns
Will not be effective against intrinsic stains
True or false… class 1 restorations include: lingual of maxillary incisors, occlusal of posteriors, and occlusal 2/3 of F/L of molars
True
In a class 1 preparation, the initial punch cut should be made where?
Most carious pit
If its a tie, start distal and go mesial for best visibility
When doing the initial prep for a class 1 restoration, you should cut ___mm inside the DEJ and…
2
Do not go any deeper even if there are caries. Then extend laterally in all directions without going deeper, until you reach sound tooth structure (AKA bounds of the disease)
True or false… for composite restorations, the initial pulpal floor should follow the rise and fall of the DEJ
True
Ideally, the isthmus of a class 1 preparation should be no more than ___mm, or ___ the intercuspal distance so that…
1
1/4
It doesn’t decrease tooth strength
How are convergent walls helpful for composite restorations?
Protect adhesive interface
Not technically retentive feature for composite
Define resistance form in regards to a class 1 cavity prep
Pulpal floor should always be perpendicular to occlusal forces
Rounded internal line angles
No unsupported enamel (cavosurface margins > 90 degrees
True or false… retention form is unnecessary for composite class 1 restorations
True
It is important to keep about ___mm of marginal ridge intact for integrity
1.6mm
When preparing the marginal ridge, there should be slight [convergent/divergent] tilting bur at ___ degrees in order to compensate for enamel rod orientation
Divergent
10
You should use ___% H3P04 for __-__ seconds. Fill in preparation and go ___ over cavosurface margins.
35%
15-30
0.5mm
Name three functions of acid etch
Removes smear layer from enamel and dentin
Selectively removes end of enamel rods (micro-roughness)
Selectively removes mineral of dentin to expose collagen fibrils
5th generation (total etch) is ___ and ___
Priming = solvent, small hydrophilic monomers
Bonding = hydrophobic monomers, filler, polymerization agents
(Primer and adhesive)
After you apply primer/adhesive you should __ for __s. Then repeat to fully infiltrate exposed collagen. Then light cure for 10s
Air dry
5s
Amalgam requires __-__mm of bulk
1.5-2mm
What is the difference between primary and secondary retention in amalgam preps?
Primary retention = occlusal convergence
Secondary retention = retention groves with 1/4 round or 169L buryou
True or false… you must desensitize the pulp with amalgam restorations. Why?
True
Amalgam is a conducting metal (temperature changes can cause rapid dentinal fluid movement)
Micro-gap along margins takes time to self-seal (perforation into gap can also cause rapid dentinal fluid movement)
What can you densensitize pulp with? What is this material made of?
GLUMA or G5
5% gluteraldehyde - fixative, plugs tubules
35% HEMA = monomer
Water
Rub into preparation for 60s and rinse for 10s
When condensing amalgam, you want to overfill by __mm in order to… (2 things)
1mm
Eliminates excess Hg
Ensures margins are completely covered
Why is secondary anatomy contraindicated in amalgam restorations?
Grooves may thin amalgam and invite chipping
What are some post op instructions you should give your patient after an amalgam restoration?
Chew on the other side until at least tomorrow so it sets fully
Tell them they should expect to feel numb for the next few hours, so do not bite cheek
Expect to feel sore for the next while, take ibuprofen PRN
What are some potential problems with a deep apical box in a class 2 composite prep?
Hard to isolate
Hard to properly matrix band and wedge
Hard to reach with curing light
Gingival wall can eventually run out of peripheral enamel and bonding to dentin is not as predictable
What is the lamination defect?
Packing composite can result in voids that can be filled with stain
What is the best design for class 2 box form that allows conservation of cusps, 90 degree exit angles?
Reverse S
How much clearance should be evident in a class 2 box form?
0.25-0.5mm on facial, lingual, and gingival walls
The matrix for a class 2 restoration must be __mm(s) higher and lower from exits of prep
1mm
What type of wedge should be used for a normal depth class 2? What type wedge for a deep prep?
Round wedge for normal depth
Triangular/anatomic wedge for deep prep near root surface
What is the purpose of dovetails in an amalgam class 2 prep?
Prevents proximal displacement
True or false… ZnO Eugenol interferes with composite
True
What is the difference between vitribond and dycal?
Vitrebond (RMGI) - acid-base; carboxyl group in PAA preferentially binds with calcium in hydroxyapatite (calcium chelation) to form a unique chemical bond
Dycal (CaOH2) - paste; irritates pulp with 11.7 pH to stimulate differentiation of mesenchymal cells to secondary odontoblasts to make tertiary dentin (best if super close to pulp. However it must be covered with vitrebond because it does dissolve)
