Operative Part 2 Flashcards by Ryan Davis

What is a GV black class 6 classification?

Just incisal edge of anterior or cusp tip of posterior

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What is friable enamel?

Enamel that is hypomineralized. Not only is it weaker, Bonding agent is not as effective in friable enamel.

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Ideally, cavosurface margins should be > or = to ___ degrees

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A cutting bur is likely to have ___ blades while a finishing bur is likely to have ___ blades

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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

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Define dental ferrule

A band that encircles the external dimension of tooth structure

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What is the minimum ferrule length when restoring a root filled maxillary central incisor with a post and core retained crown?

1.5mm

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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

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What comprises the biological width?

1mm connective tissue attachment

1mm epithelial attachment

1 + 1 = 2mm biological width

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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)

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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)

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Name two different types of chemicals used for external bleaching

Hydrogen peroxide

Carbamide peroxide

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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

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For every 10% of carbamide it forms about ___% of hydrogen peroxide. In other words, its a __:___ ratio

1:3

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True or false… there is no difference in sensitivity, rebound/regression, and results between hydrogen peroxide and carbamide peroxide

True

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What percent of hydrogen peroxide is used for in-office visits only?

30-40%

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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

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True or false… class 1 restorations include: lingual of maxillary incisors, occlusal of posteriors, and occlusal 2/3 of F/L of molars

True

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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…

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…

1/4

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)