RCC Midterm

GV black class 1-6

Class 1: Pits and Fissures

Class 2: Proximal surfaces of posterior teeth

Class 3: Proximal surfaces of anterior teeth

Class 4: Proximal surfaces of anterior involving incisal edge

Class 5: Gingival 3rd of facial or lingual surface of all teeth

Class 6: Involving cusp tips

2 Internal Walls

_____ wall: Internal wall parallel with the long axis of the tooth

_____ wall: Internal wall that is perpendicular to the long axis of the tooth and occlusal of the pulp

Axial

Pulpal

Line angle vs Point angle

Line angle is junction of two walls

Point angle is junction of three walls

Carbon steel is mainly used for

Stainless steel is mainly used for

Cutting instrument

Non-cutting such as shaping

Chisel and Excavator

Excavator is like spoon used close to dentin more control

Chisels are used to cut enamel

The working portion of a hand instrument is the ______

The handle is the ______

The portion of the instrument that connects the handle (shaft) to the blade is the

blade

shaft

shank

Instruments with longer blades require _____ complex angulation

more

The first number on a hand cutting instrument represents the ____ of the blade in ____ of mm

The second number on a hand cutting instrument represents the ____ of the blade in _____.

The third number on a hand cutting instrument represents the ____ and is measured in _____

Width, tenths (10 = 1mm)

Length, mm

Angle, centigrades (circle in 100 pieces)

(Know this)

1 mm width

6 mm length

14 centigrades

If a hand cutting instrument has 4 numbers, the second number represents the angle of the ______ ______ in relation to the long axis of the handle and is measured in _____.

cutting edge
centigrade

The gingival margin trimmer is used for ______ and beveling margins. When the second number is <85 degrees, the instrument is for _____ surfaces.

When the number is >90 degrees, it is for _____ surfaces.

smoothing
mesial
distal

Hatchet CAL 29 and 28 for amalgam

29 for mesial

28 for distal

Spoon excavators is to remove carious _____

dentin

Cleoid discoid carver

Used to carve anatomy features in newly placed restorations or can be used to remove decay and tooth tissue during cavity preparations

Can you use explorer or probe to remove things when harden

No it will bend them

Cavo surface margin is the angle formed by the junction of the wall of the preparation and the _____ surface of the tooth

untouched

Straight Handpiece

A low-speed handpiece that may be used to hold rotary instruments most commonly used in the dental laboratory.

Contra-angle handpiece

2 types are

Head is angled to provide balance, used intra-orally

Low speed: 500-15,000 rpm

High speed: 160,000 most used for cutting

Air driven handpiece

Electric handpiece

Most common instrument for cutting teeth

An alternative to the air-driven handpieces becoming more popular

Electric handpieces operate up to 40,000 rpm, significantly less than 400,000 rpm (air driven), however they have attachments with ____ that increase the effective rotational speed.

multipliers

Zach and Cohen reported that with temperature increases of more than ____°C, dental pulp could not reverse inflammation in 40% of subjects tested; an increase of ____°C over normal temperature invariably resulted in necrosis.

5.5
11

Lasers are best used in the treatment of

soft tissues

Not for prep as impossible to make margin and heat

Which bur cut by milling

Which bur cut by grinding

Carbide

Diamond

Rake Face vs Clearance Face

Rake face is contact with tooth

Clearance face is contact away from bur rotation

Soft materials (acrylics) are best cut with ______ rake angle burs and hard/brittle materials (amalgam) are best cut with _____ rake angle burs.

positive
negative

ergo

nomos

work

natural laws or systems

Most common reason for early retirement among dentists

Musculoskeletal Disorder

Classes of movement

History of dental composites first started with acid-etching and _____ bonding then _____ bonding after

Original composite were self cured, then uv cured, and now is visible light cured

enamel, dentin

Dr. Oskar Hagger patented a monomer based on _______ acid dimethacrylate chemically cured with ______ acid, which led to development of the Sevitron commercial adhesive

glycerophosphoric, sulphonic

Monomers in composites _______ and form chains which take up less space. Using larger, fewer monomers results in less _______ which allows for a better bond.

polymerize
shrinkage

Polymer chains occupy _____ space than the total volume of the monomers before polymerization

smaller

3 Components of dental composite

Resin (Organic material Bis-GMA)

Filler (Inorganic silica and glass)

Coupling Agent (Silane that bond resin and filler together)

Monomers are ____ ____ of the resin

Curing systems are the ____ for polymerization

Fillers _______ composite

Coupling agent strengthens resin by bonding _____ to the resin matrix

building blocks, Ex. BisGMA

initiators, CQ and Tertiary Amine

Strengthen, quartz, silica, glasses

Filler, Silane

Radiopaque agents

Ex: Metal Oxides

Added so that composite materials would be visible in an x-ray

Chemical Curing uses (2)

Advantage and Disadvantage

Benzoyl Peroxide and Tertiary Amines

Advantage is curing occur and bulk packing used

Disadvantage is air bubbles when mixed and cannot control work time

Light Curing Material (2) and (2) new initiator

Advantage and Disadvantage

Camphorquinone and Tertiary Amine

TPO and Ivocerin

Advantage: unlimited work time, pore free material

Disadvantage: Limited depth of cure, shrink toward bond

Dual Curing (two paste)

Advantage and Disadvantage

Advantages: Cure in regions where light may not reach

Disadvantage: Discolors easier, require 2 component resulting porosities (empty space)

Bulk fill flowable composite allows for ______ passage of light due to _______ amounts of fillers.

greater
lower

Flowable

Packable

Bulk-Fill Composites

Less filler (more shrinkage and flow)

Packable (More resistance and less shrinkage)

Bulk-fill (Modified photoinitiators to allow high depth of cure)

______ composite should not be used on occlusal surface or proximal contact area because its resistance to occlusal forces is too low due to lack of fillers

Flowable

Traditional layering technique

2 mm increments forming several layers

Bulk Fill Layering Technique

Flowable at bottom and then packable on top

Or One layer of bulk fill

Shrinkage stress may cause ____ formation between resin and the walls of the preparation with the weakest bonds (usually _____)

Marginal ____ may result in microleakage, sensitivity, staining at the margins of the restoration, and recurrent caries

gap, dentin

gaps

Avoid by C-factor

C-factor

# of bonded walls / unbonded walls ( total walls is 6)
the higher the C-factor the greater the negative effect of shrinkage

Too many bonded surface is bad

Fixed by Incremental placement

Incremental Placement of resin composites decreases the effect of _______ ______ by reducing the bulk of resin composite cured at a time; and reduces the _______, which helps relieve the stress developed at the bond between tooth and resin composite.

setting contraction
c-factor

Increments should be no thicker than

2 mm

Curing position

Cure at 90 degree angle and closer

Light curing composite predominantly employ _______ which is sensitive to blue light (420-480nm)

Photoinitiator added to enhance ______ to violet spectrum

caphorquinone

sensitivity (ex. are Lucirin, PPD, and Ivocerin)

Types of curing light by intensity lowest to highest

LED

QTH

PAC (plasma)

Laser

LED lights are introduced in the late 1990s

Able to polymerize using _____

Ensured greater depth of cure compared to ____ lights

CQ

UV

CQ vs Alternative Photoinitiators

CQ has greater curing depth but yellow coloration

Alternative such as TPO, PPD, and Ivocerin avoid yellow discoloration but reduced depth of cure

Best is hybrid

_____- wavelength photoinitiators decrease depth of cure necessitating more layers

violet

Initiators contain _____ _____ that propagates polymerization by linking the monomers.

unpaired electrons

Autocure vs Light cure and Dual Cure

Autocure: Paste, benzoyl peroxide, and tertiary amine make free radical

Light cure: blue light and phoinitiator make free radical

Dual Cure: mix of both

Adequate light curing ______ the bond strength.

doubles

Before adhesion, dentists used a ______ ______ shape to create an artificial ______ to increase retention.

dove tail
undercut

Adhesive dentistry does not require that

Adhesion or Bonding is the attachment of one substance to another by _______ forces (valence, interlocking forces)

interfacial

Adhesive or bonding agent or adhesive system is a material, a viscous fluid, that joins two substrates together and solidifies and is able to transfer a _____ from one surface to another

load

________ adhesion is penetration of resin into demineralized tissues and formation of resin tags with the tooth structure

________ adhesion is chemical bonding to the inorganic (hydroxyapatite) or organic components (mainly type ___ collagen) of the tooth structure

________ adhesion is precipitation of substances on the tooth surfaces to which resin monomers can bond mechanically or chemically

mechanical

adsorption, 1

diffusion

Steps of applying bonding agent to enamel

1. acid etch

2. rinse

3. dry

4. apply hydrophobic resin

5. light cure

Resin binds to

Biological Substrates: Enamel and Dentin

Non-biological Substrates: Ceramic and Metal

Function of acid etch

Demineralizes bonding surface to increase binding surface area

Acid Etching uses ______ acid to change enamel surface

Concentration 30 to 40%

Surface free energy is ______

Increased capillary attraction allowing penetration of ____-viscosity fluid resins

phosphoric

doubled

low

Ideal Etching time is _____ seconds

Older teeth, fluorosis, and mottled may require _____ to achieve end point

Freshly cut enamel etches ____ than unprepared

15

longer

faster

Why is the use of a rubber dam necessary when applying bonding agents

the bonding agents are hydrophobic and cannot adhere to wet surfaces

Why is it necessary to apply a bonding agent before composite?

bonding agents are more flowable and will fill in irregularities more reliably

Appearance of properly etched enamel

frosted/chalky white

Insufficient washing after etching leaves debris that interferes with the flow of _____ into the enamel channels

resin

How long should you rinse after etching enamel?

at least as long as you etched

Usually 15-30 sec

Can you overdry after you etch

Yes and will cause post op sensitivity

Etching gel or liquid?
Smooth surfaces
Deep grooves

liquids and gels have similar results
liquid etch is recommended

Etching _____ can easily thicken through evaporation

gels

Enamel Bond strength is 80kg per _____ in

0.2362

Resin tag

Extension of resin that has penetrated into etched enamel or dentin.

Adhesives used on dentin require a _______ component (primers) to interact with the dentin surface and a _______ component (bonding agents) to interact with the composite.

hydrophilic
hydrophobic

Dentin ____ are composed of a mixture of hydrophilic monomers and solvents, aiming to improve the wettability and to permit substitution of the water retained

Dentin _____ contains hydrophobic part that allows coupling with the resin-based composite

primers

bond or bonding agents

Primer vs Bond

Primer: Hydrophilic prepare for bonding

Bond: Hydrophobic that bond composite to tooth

Dentin binding steps

1. acid etch (rinse) removes smear layer
2. primer infiltrates exposed collagen network links to adhesive
3. adhesive links to resin composite

Hybrid layer

Layer formed by dentin bonding agent and collagen fibrils exposed by acid etching. Excellent layer composite can be bonded

4th generation

separate etch, primer and bond
3 steps total
gold standard for minimal sensitivity and maximum bond strength

5th and 6th generation adhesive systems

5th: 1 bottle (prime and bond) weaker

6th: 2 bottle (etch prime) (bond) less sensitivity

7th generation

single bottle contains etching agent, primer, and bonding agent
decreased sensitivity and increased bond strength

Meese prefer anterior to etch first

Do self-etching systems require rinsing?

no

Which adhesive system creates a rougher surface?

total etch
however, it relies on operator to properly fill space

T or F: you should thoroughly dry dentin after applying acid etch.

false; gently dry but do not over-dry
removal of water form the dentin structure causes loss of structural integrity
this is why we use hydrophilic primer

Dentin enzymes, matrix metalloproteinases (MMPs) and cathepsins, are responsible for the __________ of the collagen matrix of the ____ layer.

leads to destruction of the hybrid layer and loss of dentin bond strength over time.

_______ inhibits this

hydrolysis/degradation
hybrid
Chlorhexidine

Which is harder to bond dentin or enamel

dentin

no open rod to bond to

Dentin enzymes, MMP and cathepsins, are responsible for the hydrolysis/degradation of the collagen matrix of the _____ layer

hybrid

Chlorohexidine helps that

Chlorohexidine inhibits MMP’s and cathepsins, which can cause _____ of the hybrid layer. It can therefore improve durability of the resin-dentin bodn formed by an etch and rinse adhesive

degradation

Contact pressure causes ______ stresses concentrated in the _____ of the occlusal surface, and their magnitude and area of interest reached its peak during _______ ______.

tensile
grooves
maximum intercuspation.

The force of the occlusal load, and the manner in which opposing teeth occlude strongly influence the selection of ______ _______, as well as the design of the preparation and restoration.

restorative materials

Objectives of tooth preparation

1. Conservative cutting
2. Remove defects
3. Protect the pulp
4. Allow for functional, resilient, and esthetic placement of restorative material

GV black steps in tooth preparation

Establish outline form

Obtain resistance form

Obtain retention form

Obtain convenience form

Remove carious dentin

Finish walls and margins

Clean the preparation

______ _____ is based primarily on the location and extent of the carious lesion, tooth fracture, or erosion.

The extent of carious _____ should be a primary determinant of the outline form of the preparation

Outline form
dentin

In carious teeth, the outline form is established before/after penetration into carious dentin and removal of the enamel overlying the carious dentin

after

The final outline is not established until the carious dentin and usually, its overlying ______ enamel have been removed

unsupported

Which of GV black's step of preparation are not usually necessary for composite fillings?

retention form due to use of adhesives

Resistance form provides resistance to the restoration from being _______ and both the restoration and tooth will be resistant to _____ during function

displaced
fracture

Retention form is obtained through ________ ________ to retain the restoration or through ________ that attaches the restoration to the tooth surface.

mechanical shaping
bonding

Not necessary for composite filling