Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Dentistry-5th semester > Operative dentistry > Flashcards

Operative dentistry Flashcards

1
Q

Caries Management:

A
  • Risk Assessment
  • Modifying Biofilm Ecology
  • Enhance Protective Factors
  • Minimize Pathologic Factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

ICDAS:

A

A three-stage process to record the status of the caries lesion.

o First code for the restorative status of the tooth (0-8)

o Second Code for the severity of the caries lesion (0-6)

o Third Code For Activity of the lesions (+/-)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Base and Liners: If the remaining dentin thickness is between 0.5 and 1.5mm?

A

place Resin Modified Glass Ionomer (RMGI) cement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Base and Liners: If remaining dentin thickness less than 0.5mm:

A

place Calcium Hydroxide liner and then RMGI.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Base and Liners: If pulp exposure:

A

either CaOH2 or Mineral Trioxide Aggregate (MTA).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Chemically Activated (Self-cure resins):

• Two Pastes:

A

Two Pastes:

o Base: Benzoyl Peroxide Initiator

o Catalyst: Aromatic Tertiary Amine Activator Amine + benzoyl peroxide = free radical formation: addition polymerization is initiated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Advantages of Self-Cure Resins

A
  • Simple to use, no equipment needed.
  • Long term storage stability.
  • Degree of cure equal throughout material if mixed properly.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Disadvantages of Self-Cure Resins

A
  • Mixing causes air entrapment that leads to porosity and increased staining.
  • Turn yellow with time (color instability).
  • Difficult to mix evenly, causing unequal degree of cure and consequent poor mechanical properties.
  • Limited working time.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Photo-Chemically Activated (Light-Cure Resins):

• Photosensitive initiator system

A

– consisting of a photosensitizer and an amine initiator

– usually camphorquinone as photosensitizer (0.2% by weight)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Photo-Chemically Activated (Light-Cure Resins):

• Light source for activation:

A

– blue region (wavelength of about 468 nm)

– produces an excited state of the photosensitizer, which then interacts with the amine to form free radicals that initiate addition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Advantages of Light-Cure Resins

A
  • No mixing required.
  • Almost unlimited working time.
  • Avoidance of porosity of self- cure resins.
  • Once curing is initiated, 40 sec per increment are enough in comparison to several minutes for selfcure.
  • Greater color stability.
  • Allows placement of increments of different shades and translucencies.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Disadvantages of Light-Cure Resin:

A
  • Incremental placement – no more than 2mm.
  • More time consuming due to incremental polymerization.
  • Cost and maintenance of curing light.
  • Need for eye protection.
  • Limited access of curing light to proximal areas.
  • Curing light should be as close as possible to the resin and perpendicular to its surface to be most effective.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Advantages of Dual Cure Resins:

A
  • Completion of cure throughout, even if photocure is inadequate.
  • Indispensable for bonding indirect restorations.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Disadvantages of Dual Cure Resins:

A
  • Porosity due to mixing (most of these today are in mixing syringes).
  • Less color stability (aromatic amine accelerators).
  • Working time is limited.
  • Not possible to layer different shades.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  • Light cure.
  • Self-cure.
  • Dual cure.

Applications

A
  • Light cure. – Almost all multipurpose restorative composites, sealants.
  • Self-cure. – Resin cements and core build up materials.
  • Dual cure. – Resin cements, core build up materials.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Oxygen Inhibited Layer:

A

The polymerization is inhibited by oxygen because the reactivity of oxygen to a radical is much higher than that of a monomer.

  • Unpolymerized surface layer.
  • Affects more the self-cure than the lightcure resins.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Degree of Conversion (DC):

A

Ratio of bonded to unbonded surfaces

  • The percentage of carbon-carbon double bonds that have been converted to single bonds to form a polymeric resin.
  • The higher the DC, the better the properties of the composite resin and thus, the performance.
  • DC in direct composites is 50-70%.
  • Similar for self-cure and light-cure. • Better for indirect composites.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Bisphenol A (BPA) Toxicity:

A
  • Precursor of Bis-GMA contained in some sealants. • Mimics the effect of estrogens.
  • Has anti-androgenic activities.
  • Effects on humans are unclear.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Polymerization Stages:

A
  1. Initiation. – Free radical formation (initiator). –Reaction of free radical with the first monomer.
  2. Propagation. –Monomers convert into polymers.
  3. Termination. –Reaction stops.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Self – Cure Resins:

A
  • Chemically initiated at room temperature with a peroxide initiator (base) and an amine accelerator (catalyst).
  • Similar would happen with heat (50 – 100o C).
  • The amine actually drops the temperature where the BPO produces free radicals.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Light – Cure Resins:

A
  • Photons from a light source activate the initiator to generate free radicals that, in turn, can initiate the polymerization process.
  • Camphorquinone and an organic amine generate free radicals when irradiated by light in the blue to violet region.
  • Light with a wavelength of about 470 nm is needed to trigger this reaction.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Curing Energy:

A
  • Energy = intensity of light + duration of light application over a given area.
  • Typical composite requires a 40 sec exposure to 400 mW of 400 – 500nm light per cm2. or
  • Typical composite requires 16 Joule (1J = energy generated from 1W in 1sec.).
  • However, 400mW/cm2 x 40sec = 800mW/cm2 x 20sec
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Wavelength Requirements of the Photo- Initiator:

A
  • Camphorquinone = 460 to 470 nm.
  • Lucirin TPO = 410nm.
  • Ivocerin (Germanium based = 460nm.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Light Curing Rules:

A
  • Exposure: 20 sec for bonding agent, 40 for each layer of composite.
  • Intensity: 468 ± 20 nm blue light > 400mW/cm2
  • Distance and angle between light and resin: As close as possible, as perpendicular as possible.
  • Thickness of resin: < 2mm per layer.
  • Shade of resin: The darker and more opaque, the thinner the layer should be.
  • Type of filler: The more filled the composite, the easier it will cure.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Tungsten Halogen Curing Lights:

A
  • 50 – 100 watt bulb to produce 500 mW of light that peaks at 468 nm.
  • Efficiency rate of only 0.5%; the other 99.5% is simply heat.
  • Big and noisy.
  • Energy consuming.
  • Need to replace the bulb often as efficiency drops.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Light Emitting Diode – LED:

A
  • Consume very low energy.
  • Can be wireless.
  • Narrow bandwidth of light, 450 - 490 nm.
  • Efficiency of about 16%.
  • Produce less heat.
  • No fan to cool it.
  • 1000 to 1400 mW/cm2.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Glass Ionomer Cements (GIC): composition:

A

Fluoro-Alumino-Silicate Glass Powder + Polyacrylic Acid = GIC • Acid – Base Reaction

• The Acid attacks the glass releasing metal cations which are chelated by the carboxylate groups and crosslinking of the polyacid chains happen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

GIC-Chemical Adhesion to Hydroxyapatite:

A
  • Bonding happens because the carboxyl groups of the polyacrylic acid react with Calcium of the Hydroxyapatite.
  • Bonds better to enamel than dentin, due to higher inorganic content.
  • Self-bonding is the main advantage of GICs.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

GIC-Fluoride Release:

A

• Large amounts in the first 24 hours and then lower. • Higher is not necessarily better.

– The F- is exchanged with OH- and this acidifies the surrounding medium.

– If the pH falls under 4, the mineral will resolve and reprecipitate as CaF2.

– If the pH is 4-4.5 it reprecipitates as Fluorapatite.

  • Can be recharged with Fluoride (F reservoir).
  • Fluoride release does not affect the properties of the cement.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

GIC-Disadvantages:

A
  • Very prone to water intake the first 24 hours. Needs to be protected until maturing. Usually with a varnish.
  • Needs to be precise in the mixing ratios.
  • Limited working time.
  • Prone to acid erosion.
  • Low fracture toughness and strength.
  • Low wear resistance.
  • Less esthetic than composites (less translucency, less polishable, staining, discoloration).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

GIC-Clinical Applications:

A
  • Luting cement (crowns, bridges, ortho braces).
  • Bases and liners.
  • Restorative material (mainly Class Vs and root caries).
  • PF Sealants.
  • Core build up.
  • Seal endodontic access cavities.
  • Restorations on deciduous teeth.
  • Temporary restorations.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Resin Modified Glass Ionomer Cements:

A
  • Water-soluble methacrylate-based monomers (usually HEMA) replace part of the polyacrylic acid liquid.
  • Acid – Base reaction will occur but they are also lightcured.
  • Same bonding mechanism with conventional GICs.
  • More shrinkage, more microleakage, more convenience, less water susceptibility in the first 24hours.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

R.M.G.I-composition:

A
  • Powder and liquid.
  • Acid – base reaction happens slower.
  • Do not require a bonding agent.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Compomers:

A
  • Polyacid-modified composites.
  • Glass particles of GIC incorporated in waterfree polyacid liquid monomer with appropriate initiator.
  • One syringe, light cure only.
  • The idea is the integration of the fluoride- releasing capability of glass ionomers with the durability of resin composites.
  • Require a bonding agent.
  • Probably instead of providing the advantages of both materials they provide the disadvantages of both.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Base:

A

• Any substance placed under a restoration that

– blocks out undercuts in the preparation.

– serves as a replacement or substitute for dentin.

– can be shaped and contoured to specific forms.

– acts as a thermal or chemical barrier to the pulp.

– controls the thickness of the overlying restoration.

• Main use today is blocking undercuts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Liner:

A
  • A fluid paste applied in a thin layer as a protective barrier between dentin and the restorative material.
  • May provide some therapeutic benefits.
  • Liners should not be used in layers thicker than 0.5 mm.
  • Varnish
  • Calcium hydroxide.
  • Zinc oxide-eugenol.
  • Glass ionomer.
  • Resin modified glass ionomer.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Bases – Zinc Phosophate Cement:

A
  • Very long history of use in dentistry.
  • Still a decent material to cement indirect, retentive restorations.
  • Not used as a base anymore.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Bases – Polycarboxylate Cement:

A
  • Has been considered friendly to the pulp.
  • Not strong.
  • Not frequently used any more.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Bases – Zinc Oxide-Eugenol (ZOE):

A
  • Has been used in dentistry as a base, liner, cement, and provisional restoration for decades.
  • Excellent thermal insulation.
  • Antibacterial properties (eugenol release)
  • Very good temporary filling material.
  • INCOMPATIBILITY TO BONDING.

– Use amalgam or

– Enlarge the cavity ( a few microns) or

– Use a different material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Varnish E.g. Copalite, Cooley&Cooley, Copaliner, Bosworth:

A
  • Placed in the tooth preparation prior to placement of an amalgam restoration to seal the tubules and reduce the effects of microleakage.
  • Will be dissolved by oral fluids and replaced by the corrosive byproducts of the amalgam.
  • Not used anymore as we have more effective materials.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Ideal Properties of Bases & Liners:

A
  • Friendly to the pulp.
  • Bonding to dentin.
  • High compressive and tensile strength.
  • Radiopacity.
  • Controlled dispensing.
  • Easy mixing and easy cleanup.
  • Rapid setting.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Glass Ionomer Setting Reaction:

A
  • Acid-base reaction with polyacrylic acid acting on and partially dissolving alumino-silicate glass.
  • This reaction results in a significant fluoride release at a very high level, completed in 24 hours.
  • After that, there is a continual low-level release of fluoride that is likely well below the threshold necessary to protect against secondary caries.
  • GI materials must be “recharged” with fluoride, which can then be re-released in order to provide protection.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Resin – Modified Glass Ionomer – RMGI (e.g. Vitrebond):

A
  • Light activated.
  • Improved handling characteristics and physical properties compared to regular glass ionomer materials.
  • They bond very predictably to dentin, provide an excellent seal, and are very compatible with the pulp.
  • Fluoride release.
  • Typically they are used as a thin liner (0.5 mm) over dentin in deep cavity preparations.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

GI / RMGI Cements

A
  • The reason they are the preferred base/liner materials is their predictable bond and seal of the underlying dentin, not their ability to prevent secondary caries due to fluoride release.
  • RMGI liners have an excellent track record as lining materials used in films no thicker than 0.5 mm.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Calcium Hydroxide:

A
  • Very high, basic pH (11–14).
  • Antibacterial.
  • Promotes secondary and reparative dentin formation.
  • Not as a base as it has very poor physical properties.
  • Highly soluble in water.
  • In very thin layer (0.5 mm) over the deepest portion of the cavity preparation.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

2020 EUC Operative Dentistry Protocol:

A
  • If the remaining thickness of dentin is less than 2mm between the pulp and the pulpal floor, we will place GI or RMGI cement as a liner.
  • The goal is to seal deep dentin and have 2mm of dentin + liner between the pulp and the restorative material.
  • In case of pulp exposure or pink color showing from the pulp (less than 0.5mm to the pulp), place minimal MTA or Ca(OH)2 and cover with RMGI.
  • Follow the above protocol for deep preparations or pulp exposures to non symptomatic teeth (RMGI or MTA / Ca(OH)2 + RMGI).
  • Follow the above protocol for deep preparations or pulp exposures to non symptomatic teeth (RMGI or MTA / Ca(OH)2 + RMGI).
  • RMGI in moderate depth tooth preparations is optional.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Goals of Isolation:

A
  • Moisture control
  • Retraction and access
  • Protection and harm prevention
  • Protection of a tooth against bacterial contamination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

There are 3 Types of Distraction that could affect work.

A
  • Visual Distraction
  • Manual Distraction
  • Mental Distraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Latex Allergy:

A

Be aware that latex allergy may be as high as 6% in dental staff and 9.7% in dental patients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Winged Vs Wingless Clamps:

A

The W letter indicates that the clamp is wingless. Those clamps that do not bear a W have wings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Winged clamps:

A
  • Have anterior and lateral wings
  • Give extra retraction of the rubber dam from the operating field
  • Interfere with the placement of matrix bands and wedges
  • Are used more often for endodontic treatment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Wingless clamps:

A
  • Are used more often for restorative treatment
  • Provide less retraction of the rubber dam
  • Provide more space at the proximal areas for matrix bands and wedges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Passive Vs. Active Clamps:

A
  • Passive clamps have jaws which are flat, facing each other. They grasp the tooth at or above the gingival margin and cause minimal gingival trauma.
  • Active clamps have jaws directed more gingivally and grasp the teeth below the gingival margin. Jaws are narrow, curved and slightly inverted which displace the gingivae.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Extended bow clamps:

A

The Dentsply HW pattern or the Ash AD pattern are special clamps in which the bow lies more distally than that of a standard clamp. This is especially helpful if the preparation of the distal surface of a clamped tooth is necessary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Serrated clamps:

A

they have serrated jaws for improved retention on broken down teeth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

S-G (Silker –Glickman ) clamp:

A

anterior extension in this clamp allows for retraction of dam around severely broken down teeth while the clamp itself is placed on a tooth proximal to one being treated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Clamps with long guard extension:

A

these protect the cheek and tongue. Some of them have a tube-like perforated extension which hold cotton roll in the sulcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Non-metallic clamps:

A

are now available which are made from polycarbonate plastic**, they are **radiolucent, they are bulky and they do not fit the teeth very well

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Cervical Retracting Clamps (E.g Brinker’s):

A
  • These can be single-bowed or double- bowed but the jaws are movable even after attaching the clamp to the tooth
  • By moving the jaws apically the gingivae can be retracted apically
  • They are used in conjunction with a major anchor clamp
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Materials For Sealing Voids:

A

Cases will arise when it is not possible to achieve a moisture-proof seal with the rubber dam. Small leaks or gaps can be sealed by the application of materials such as:

  • Oraseal
  • Light-cured resin barriers
  • Cavit
  • Teflon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Adhesion:

A

The state in which two surfaces are held together by interfacial forces which may consist of valence forces or interlocking forces or both.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Mechanics of Adhesion in Dentistry:

A
  • Adsorption
  • Diffusion
  • Mechanical adhesion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Adsorption:

A

chemical bonding to the inorganic component (hydroxyapatite) or organic components (mainly type I collagen) of tooth structure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Diffusion:

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Mechanical adhesion:

A

penetration of resin and formation of resin tags within the tooth surface.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Failure of Adhesion:

A
  • Cohesive failure in the substrate.
  • Cohesive failure within the adhesive.
  • Cohesive failure in the restorative material.
  • Adhesive failure (failure at the interface of the substrate or the restorative material and the adhesive).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Michael Buoncore Eastman Dental Center - USA:

A

Sealing of pits and fissures with an adhesive resin: its use in caries prevention.

68
Q

Acid Etching:

A

Acid etching transforms the smooth enamel into an irregular surface and increases its surface-free energy.

69
Q

Resin Tag Formation:

A
  • A fluid resin-based material is applied to the irregular etched surface and the resin penetrates into the surface.
  • Monomers in the material polymerize, and the material becomes interlocked with the enamel surface. →The formation of resin micro-tags within the enamel surface is the fundamental mechanism of resin-enamel adhesion.
70
Q

Enamel Adhesion:

A
  • Acid Etch (phosphoric acid 35% for at least 30 sec).
  • Resin tags.
  • High bond strength.
  • Reliable bond.
71
Q

Dentin Adhesion:

A

Materials can interact with dentin mechanically or chemically or both.

  • Major mechanism of adhesion is micromechanical interlocking of resin into the network of collagen fibrils left exposed by acid etching.
  • Glass ionomer cements and some phosphatebased self-etch adhesives, offer some chemical bonding. →Dentin is a dynamic substrate and consequently, adhesion is difficult and unpredictable. Dentin adhesion is not reliable
72
Q

Challenges in Dentin Adhesion:

A
  • Dentin contains water and organic substance, mainly type I collagen. Enamel contains mainly hydroxyapatite.
  • The number of tubules is increasing closer to the pulp in number and size. The quality of adhesion gets lower.
  • Dentin is an intrinsically hydrated tissue.
  • Fluid filled tubules with a collagen network lining the inter-tubular dentin.
  • Resins are hydrophobic.
  • Degradation of collagen by dentin proteinases is known to negatively affect the bonded interface.
  • It happens in varying time after the etching and application of the adhesive.
73
Q

Smear Layer:

A

Whenever tooth structure is prepared with a bur or other instrument, residual organic and inorganic components form a “smear layer” of debris on the surface.

• The smear layer fills the orifices of dentin tubules, forming “smear plugs”.

74
Q

Dentin Adhesion-Procedure:

A

• Etch for 15 seconds to:

– remove the smear layer.

– Demineralize inter-tubular and peri-tubular dentin.

– Expose collagen fibrils.

75
Q

Hybrid Layer Formation:

A

Resin infiltration of acid etched dentin transforms the surface

  • from crystalline, acid- sensitive and relatively hydrophilic
  • to an organic structure, acid resistant and relatively hydrophobic
76
Q

Wet Dentin Adhesion:

A
  • A method for bonding to tooth structure using phosphoric acid as a dentin-enamel conditioner.
  • Improved bond strength through acid- etching of dentin and bonding to wet dentin surfaces.
  • Drying etched dentin results in a 2/3rds reduction of its volume.
  • The collagen fiber network in etched dentin literally floats in water.
  • If dentin is dried, the hybrid layer cannot be formed.
77
Q

Bonding Agent Generations:

A

1st, 2nd, 3rd generation:

• NOT bonding to dentin.

4th generation:

• The first hydrophilic dentin bonding agents. Compatible to dentin.

78
Q

Three – Step Etch – and – Rinse:

A
  1. Phosphoric acid approximately 35% that is rinsed.
  2. A primer containing reactive hydrophilic monomers in ethanol, acetone, or water.
  3. A non solvated unfilled or filled resin bonding agent. Contains hydrophobic monomers such as Bis-GMA, frequently combined with hydrophilic molecules such as HEMA.
79
Q

Three Step Etch and Rinse Adhesive System (4th Generation): Advantages:

A
  • They do work.
  • Longest track record.
  • Versatility.
  • Dual cure.
  • Compatible with all composites.
  • Still considered the Gold Standard.
80
Q

Three Step Etch and Rinse Adhesive System (4th Generation): Disadvantages:

A
  • Technique sensitivity.
  • No HAp to protect the collagen.
  • Cost.
  • Ease of use.
81
Q

Solvents:

A
  • The carrier of the bonding agent to dentin
  • Highly hydrophilic Solvents Can be:
  • Acetone
  • Ethanol
  • Water
82
Q

Acetone:

A
  • Wet dentin.
  • Immediate application.
  • Apply in high quantity.
  • Dry.
  • Excellent bonding.
83
Q

Ethanol:

A
  • Less wet dentin (almost dry).
  • Apply and wait.
  • Difficult to remove solvent.
  • Excellent bonding.
84
Q

Water:

A
  • Dry dentin.
  • Apply for at least 30 sec.
  • Difficult to remove solvent.
85
Q

Two Step Etch & Rinse Adhesive Systems (5th Generation): Advantages:

A
  • Good immediate bonding.
  • Ease of use.
  • Low cost.
86
Q

Two Step Etch & Rinse Adhesive Systems (5th Generation): Disadvantages:

A
  • Acidic and hydrophilic.
  • No Hap to protect the collagen.
  • Faster degradation.
  • Incompatibility with self cure resins.
  • Light cure only.

→Τhree-step etch-and-rinse adhesives result in better laboratory and clinical performance than two-step etch-and-rinse adhesives

87
Q

Two – Step Etch – and – Rinse Adhesives:

A
  • Do not contain a final hydrophobic bonding agent layer.
  • Contain solvents and other hydrophilic components from the primer that are mixed with the hydrophobic monomers from the bonding agent.
  • For this reason, hydrolytic degradation, which directly relates to the hydrophilicity of the adhesive, is more evident in two-step etch-and-rinse adhesives when compared to their non simplified predecessors.
88
Q

Self – Etch Approach:

A
  • No etching and no rinsing.
  • Smear layer is not removed.
  • More superficial interaction with dentin (depending on the pH of the Adhesive).
  • HAp preservation.
  • Etching of enamel is not adequate (depending on the pH of the Adhesive).
89
Q

Two Step Self Etch Adhesive Systems: Advantages:

A
  • Modifies smear layer.
  • Less post-operative sensitivity.
  • Ionic interaction with HAp – self assembled nano layering.
  • 10 – MDP.
  • Final hydrophobic layer.
  • Protection of collagen (Hap).
  • Less technique sensitivity.
  • No need to rinse.
  • Excellent bonding (with SEE)
90
Q

Two Step Self Etch Adhesive Systems:

Disadvantages:

A

• Not adequate enamel etch.

91
Q

One Step Self Etch Adhesive Systems: Advantages:

A

• Ease of use

92
Q

One Step Self Etch Adhesive Systems: Disadvantages:

A
  • Not adequate enamel etch.
  • Too acidic and hydrophilic after curing – water tree formation
  • Water permeability and fast degradation of the bond.
  • Self cure resin incompatibility.
  • Hydrolysis in the bottle.
93
Q

Hydrophilicity & Dentin:

A
  • In order for hybridization to happen we need a primer that is compatible to dentin and this HAS to be hydrophilic as dentin is by definition a wet substance. You cannot dry dentin.
  • SE also need to etch dentin. So they contain acids to be able to etch and also to be hydrophilic.
  • The acids used in the SE primers are very hydrophilic.
  • So, you want both acidity and hydrophilicity. This, at the time of placement of your adhesive, so you etch and hybridize.
94
Q

Acidity of Self – Etch Systems (pH):

A

pH < 2

  • Demineralization of Hydroxyapatite.
  • Exposure of collagen fibrils.
  • Incorporation of instable CaPO4 that are not rinsed away.

pH ≥ 2

  • Protection of collagen due to maintenance of HAp.
  • Ionic interaction with HAp.
  • Chemical bond (similar to Glass Ionomer cements). HIGH STABILITY OF DENTIN BOND INADEQUATE BOND TO ENAMEL (insufficient etching)

pH ≥ 2: SELECTIVE ETCH

A separate etching step of enamel is greatly improving the bond.

95
Q

Selective Enamel Etch with SE bonding agents:

A

S.E.E. ONLY ENAMEL!!! Extension of a one-step self-etch adhesive into a multi-step adhesive

96
Q

Universal (2012 – All Bond Universal):

A
  • With or without etching
  • Direct or indirect restorations
  • Self cure or light cure
  • For all substrates and materials
  • Contain silane
  • Contain 10-MDP
97
Q

Functional Monomer: 10 - MDP

A
  • Interacts with Hap to create very stable Ca – salts through self-assembled nano-layering.
  • Strong hydrophobic nature that protects the bond against degradation.
  • Makes the residual Hap more resistant to acidic dissolution.
  • The Hap-10-MDP hybrid layer protects the collagen as a shelter.
98
Q

Universal One Step Self Etch Adhesive Systems:

Advantages:

A

• Improved version of all in one Self Etch systems.

o 10-MDP

o Ultra mild or mild

99
Q

Universal One Step Self Etch Adhesive Systems: Disadvantages:

A
  • Not adequate enamel etch.
  • Too acidic and hydrophilic after curing.
  • Water permeability and fast degradation of the bond.
  • Self cure incompatibility.
  • Hydrolysis in the bottle.
  • Lack long term research data.
  • Extremely limited clinical research data.
100
Q

Universal Adhesive Systems:

A
  • Always use a SEE strategy.
  • Additional hydrophobic layer.
  • Active application of the adhesive (scrubbing).
  • MMP inhibitors (BAC, Chlorhexidine).
  • Use separate silane for silica based ceramics.
101
Q

What Bonding System?

A
  • Low technique sensitivity
  • H3PO4 enamel etching
  • Mild self etching if SE
  • Final hydrophobic layer
  • Not acidic after curing
  • Dual Cure
102
Q

Universal Adhesives and Silane:

A
  • Silane does not work well when combined with resin monomers.
  • Silane is deactivated in low pH environments.
103
Q

Universal Adhesives & Zirconia / Metal Primers:

A
  • Abrasive treatment needs to precede Zirconia priming.
  • There is indications that UA work but also that bond stability may be worse.
  • Reliable bond to Zirconia is anyway challenging with any strategy.
104
Q

Conventional Cements:

A

– Zinc Phosphate cement.

– Zinc Polycarboxylate cement.

– Glass ionomer cement.

– Resin modified glass ionomer cement.

– Zinc Oxide Eugenol cement.

105
Q

Adhesive Cements:

A

– Light cure resin cements.

– Dual cure resin cements.

– Self cure resin cements.

– Self etch resin cements.

106
Q

Temporary Cements E.g. ZOE:

A

– Allows the restoration to be removed after assessment of its performance.

Need Caution as:

  • Restoration may not be easily removed.
  • Restoration may dislodge.
  • Patient may not return for permanent cementation.
  • Avoid temporary cementation of single unit restorations to avoid risk of ingestion or inhalation.
107
Q

Definitive Cements:

A

– Usually the restoration must be destroyed to be removed.

108
Q

Inverting The Dam:

A

Involves tucking the rubber dam under the gingival margin, into the sulcus, allowing the dam to seal more tightly against the tooth and prevent leakage

109
Q

Single tooth isolation may be used for :

A
  • Fissure sealants
  • Class 1 and 5 restorations
  • Endodontics
110
Q

Multiple tooth isolation :

A
  • Class 2 restorations
  • Multiple restoration and quadrant dentistry
  • Bonding indirect restorations
111
Q

Rules For Multiple Tooth Isolation:

A
  • The general rule is to include at least one tooth posterior and two teeth anterior to the teeth being treated
  • When operating on incisors isolate from premolar to premolar
  • When operating on canine isolate from first molar to the opposite lateral incisor
  • When operating on premolars include two teeth distally and extend anteriorly to the opposite lateral incisor
  • When operating on molars, punch holes as far distally as possible, and extend anteriorly to the lateral incisor of the opposite side
  • Anterior teeth may be included to provide better access and visibility and also to provide better finger rest
  • Anterior teeth may be included because their less tight contact points allow easier placement of the dam without the need of using floss
  • The rubber dam is first passed over the clamp of the most posterior tooth, it is then anchored on the anterior teeth and is finally flossed through the teeth in between
112
Q

Enamel Adhesion: seconds

A

at least 30 sec

113
Q

Dentin Adhesion: sec

A

Etch for 15 seconds

114
Q

Hybrid Layer Formation:

A

Resin infiltration of acid etched dentin transforms the surface

• from crystalline, acid- sensitive and relatively hydrophilic

115
Q

Conventional cements:

A

– Retentive conventional castings such as porcelain fused to metal crowns and bridges or metal inlays/onlays.

– Retentive tooth colored restorations that is indicated to be conventionally cemented (e.g. Zirconium oxide).

– Metal prefabricated or cast posts.

  • Conventional cements are usually ionic and susceptible to acid attack, so they are more soluble in the oral environment.
  • The success of restorations cemented with conventional cements relies on the excellent adaptation of the casting to the prepared tooth.
116
Q

• Adhesive cements:

A

– All ceramic restorations that require adhesive bonding (e.g. feldspathic porcelain veneers, inlays/onlays).

– Non retentive conventional castings (e.g. PFM crowns).

– Resin bonded bridges.

– Non retentive natural tooth colored restorations (e.g. Zirconium oxide or lithium disilicate crowns). – Posts of any type.

117
Q

Zinc Phosphate Cement:

A
  • Very long successful track record.
  • Low film thickness (25μm).
  • Easy cleanup of excess cement.
  • Good working time (5 min) that can be slightly manipulated.
118
Q

Zinc Polycarboxylate Cement:

A
  • Considered more biocompatible.
  • Not very strong.
  • More difficult to use than Zinc Phosphate.
  • Thicker consistency during mixing.
  • Low working time (2.5 min).
  • More difficult to clean up than zinc phosphate.
119
Q

Glass Ionomer Cement:

A
  • Biocompatible.
  • Chemical bonding to dentin.
  • Fluoride release.
  • Stronger than zinc phosphate and zinc polycarboxylate.
  • Should be protected from water for at least 10 min.
120
Q

Resin Modified Glass Ionomer Cement:

A
  • May be less soluble and stronger than GIC.
  • Can be light cured.
121
Q

Complex Amalgam Preparations: Resistance And Retention Forms

A

When conventional retention features are not available, additional features may be needed:

– Slots

– Pins

• Type of additional retention form depends on the tooth and on the available tooth structure.

122
Q

Contraindications:

A
  • When a proper anatomic and functional form cannot be achieved with a direct restorative material
  • When the tooth is esthetically important to the patient.
123
Q

Complex Amalgam Preparations:

A
  • Use your bur to reduce the cusp
  • You can use depth cuts
  • 2mm for the functional cusps and 1.5mm for the non functional cusps.
124
Q

Complex Amalgam Preparations:

Cusp reduction and coverage:

A

Cusp reduction and coverage reduce the amount of vertical preparation wall height and increase the need for the use of secondary retention features.

125
Q

Complex Amalgam Preparations:

Mandibular First Premolar:

A
  • Usually the lingual cusp needs to be reduced.
  • Be very careful as it is easy to completely remove the lingual wall.
  • Depth cuts of 1.5mm help reduce the correct amount.
  • You need to keep even a small portion of the lingual wall to help with retention.
126
Q

Complex Amalgam Preparations: Maxillary First Molar

A
  • Usually the distolingual cusp needs to be reduced.
  • The lingual prep can be extended as needed for retention.
  • Completed depth groove
  • Lingual groove may be extended arbitrarily to increase retention
  • Opposing vertical walls should converge when possible.
  • Pulpal and gingival floors should be flat and perpendicular to the long axis of the tooth. Secondary retention is usually needed.
127
Q

Complex Amalgam Preparations:

Mandibular First Molar

A
  • Usually the distal cusp needs to be reduced.
  • A minimum reduction of 2mm is needed.
128
Q

slot:

A
  • When there is no vertical walls, slots may be needed for retention.
  • A slot is a horizontal retention groove in dentin.
  • Placed in the gingival floor of a preparation.
129
Q

Slots Should Be:

A
  • 1mm wide
  • 1mm deep
  • In the line angle areas of the tooth
  • 2 – 4mm in length – depending on the distance between vertical walls
  • 0.5 – 1mm inside DEJ
  • 1 slot per missing axial line angle
130
Q

Types of Pins:

A
  • Cemented pins
  • Friction-locked
  • Self-threading pins
131
Q

Self-Threading Pins:

A
  • The most retentive of the three types of pins.
  • Three to six times more retentive than cemented pins.
  • Recommended pinhole depth is around 2mm.
  • Non-parallel placement of the pins is increasing retention.
  • Bending pins is not advised as amalgam may not be adequately condensed.
  • Increasing the number of pins increases retention BUT
  • Crazing and potential for fracture increases.
  • The strength of the restorations decreases.
132
Q

Number of pins Depends on:

A
  • The amount of missing tooth structure
  • The amount of dentin available to safely receive the pins
  • The amount of retention required
  • The size of the pins. As a general rule, one pin per missing axial line angle should be used.
133
Q

Pinhole Location:

A

Usually, pinholes should be located close to the line angles of the tooth.

Pinhole should be parallel to the adjacent external surface of the tooth.

-Pinhole should not be too close to a vertical wall (minimum 0.5mm clearance).

  • Position relative to the DEJ: 1mm in dentin.
  • Position relative to the external tooth surface: 1.5mm.
134
Q

Pulpal Perforation

A

Treat as pulp exposure:

– Control hemorrhage

– Place MTA or Ca(OH)2

– Prepare another pinhole 1.5mm away

  • In most of the cases, endodontic therapy will be needed.
  • Always do endodontic therapy in these teeth, before an indirect restoration.
135
Q

Benefits of a Properly Finished & Polished Restoration:

A
  • Prevention of recurrent decay
  • Prevention of amalgam deterioration.
  • Maintenance of periodontal health
  • Prevention of occlusal problems.
136
Q

Conventional Resin Cements:

A
  • Require an etch and rinse or self etch bonding agent.
  • Self cure, dual cure or light cure.
  • Better mechanical properties.
  • Usually come in multiple shades.
  • May have water soluble try-in pastes.
137
Q

Self – Etch or Self – Adhesive Resin Cements:

A
  • Do not require a bonding agent.
  • Are acidic and contain hydrophilic primers.
  • Usually dual cure. • Contain MDP-10.
  • Significantly weaker than conventional resin cement.
138
Q

Resin Cements:

A
  • They are composite resins.
  • They differ in the mode of polymerization.
  • They have low viscosity to be used as cements.
  • They bond to tooth structure same like the restorative composite resins.
  • They are either dual cure or self cure.
  • There are light cure resin cements used only for the thin porcelain veneers (<1mm).
139
Q

cements-Pre – Treatment Restorations:

A
  • Microetching (sandblasting/air abrasion).
  • Hydrofluoric acid + silane primer.
  • Zirconia/metal primers.
140
Q

cements:

Microetching:

A
  • Increasing bonding surface by microabrading and roughening.
  • Usually 50μm aluminum oxide powder.
  • To all indirect restorations.
141
Q

Porcelain Bonding:

A
  • Acid etchable / non – etchable materials.
  • Acid etching with Hydrofluoric acid greatly increases bond strength to porcelain.
  • Silane primer application on HF etched porcelain.
142
Q

Zirconia Primers:

A
  • Bonds to zirconium oxide and resin cement.
  • Significantly increases bonding strength to zirconia based ceramics.
  • MDP-10 (acidic monomer).
  • The phosphate ester group of MDP chemically bonds to metal oxides and zirconia based ceramics.
143
Q

Zirconia Pre Treatment:

A
  • Air abrasion + Zirconia primer.
  • Tribochemical silica coating + silane coupling agent to achieve chemical bonding to the silica-coated surface.
144
Q

The Extended Ecological Plaque Hypothesis:

A

The acidogenicity and acid tolerance of plaque increase due to microbial selection** and **adaptation.

145
Q

Gastroesophageal reflux disease (GERD) compared with healthy (Control):

A
  • No difference in caries activity or experience
  • No difference or lower numbers of lactobacilli and mutans streptococci
  • Contradictory results in children
146
Q

The Hypothesis of Autoinducer 2 – Autogenic Succession:

A

Another “ecological plaque hypothesis” Increased concentration of Autoinducer 2 favors transition and growth of pathogenic (cariogenic) bacteria.

147
Q

MDP Catabolism and Dental Caries:

A

Twenty minutes after sugar intake, the MDP of cariesactive subjects has:

  • lactate >3 mM
  • pH <5.7
  • Increased acidogenic potential
  • Longer demineralization period
148
Q
A
149
Q

Inhibitors:

A
  • • To prevent spontaneous or accidental polymerization of the monomers.
  • After the inhibitor is consumed, the polymerization reaction starts.
  • Usually butylated hydroxytoluene (BHT) in 0.01% by weight.
150
Q

Composite Resin Toughness:

A
  • Resin matrix is weak, fillers are strong.
  • Strength of composite resin is highly dependent on the ability of the coupling agent to transfer stresses from the weak matrix to the strong filler particles.
  • Matrix and filler should be chemically bonded to each other. If not, fillers will act like voids and a resin crack will propagate.
151
Q

Curing Shrinkage:

A
  • The space occupied by the monomer is reduced as it converts to polymer about 20%.
  • The composite shrinks anywhere around 2 – 7%.
  • The shorter the monomer, the more the shrinkage.
  • This produces unrelieved stresses in the resin after it starts hardening.
  • Also produces shrinkage stress in the interface of the composite with the tooth.
  • Curing shrinkage and shrinkage stress are affected by: • Total volume of the composite material.
152
Q

Wear:

A
  • Volume lost by contact with opposing teeth, etc.
  • 10 – 20μm per year.
  • Composites wear more than enamel.
  • Composites with small filler particles (< 1μm) are more resistant to wear.
  • Greatly depends on the patient.
  • The Smaller the filler, the better the wear characteristics of the composite
153
Q

Pinhole Location:

A
  • Pinhole should not be too close to a vertical wall (minimum 0.5mm clearance).
  • Position relative to the DEJ: 1mm in dentin.
  • Position relative to the external tooth surface: 1.5mm.
154
Q

Pin:

Pulpal Perforation:

A

Treat as pulp exposure:
– Control hemorrhage
– Place MTA or Ca(OH)2
– Prepare another pinhole 1.5mm away

  • In most of the cases, endodontic therapy will be needed.
  • Always do endodontic therapy in these teeth, before an indirect restoration.
155
Q

Finishing:

A

removing marginal irregularities, defining anatomical contours, and smoothing the surface roughness of the restoration.

  • contouring
  • removal of marginal discrepancies
  • defining the anatomy
  • smoothing the amalgam surface.
  • Requires abrasive agents that are coarse enough to remove the bulk from the surface
156
Q

Polishing:

A

to obtain a smooth, shiny luster on the surface.

  • producing the smoothest and shiniest surface possible
  • Requires more mildly abrasive materials for smoothing and shining the surface
157
Q

Benefits of a Properly Finished & Polished Restoration:

A

Prevention of recurrent decay

  • potential of increased plaque accumulation and retention of debris, especially at the margins

Prevention of amalgam deterioration.

  • Tarnish
  • Corrosion – results in deterioration of the margins

Maintenance of periodontal health

  • Improperly contoured restorations destroy the periodontium as Oral hygiene is impossible.
  • Open contacts result in food trapping.
  • Overhangs may result in dental floss catching.

Prevention of occlusal problems.

  • Premature occlusion leads to occlusal trauma, pain and sensitivity especially during mastication.
  • The restoration may break
  • A restoration in the antagonist tooth may break.
158
Q

Finishing-Amalgam:

When:

A

Finishing procedures should be completed before the amalgam starts to set. If additional contouring or finishing is needed, it should happen after 24hrs.

159
Q

Polishing-Amalgam:

When?

A

Polishing procedures should not be initiated until the amalgam has reached its final set, at least 24 hours after it has been placed.

  • Composite resins are polished immediately after placement and curing.
160
Q

Polishing agents - Amalgam:

A

Pumiceandtinoxidecanbeusedfor polishing amalgams

– Pumice is an abrasive powder of volcanic origin.

– Usually mixed with water (slurry of pumice).

– Tin oxide may be applied in a slurry or dry.

– Both are used with separate non abrasive rubber cups.

161
Q

Hypotheses For the etiology of caries:

Specific Versus Non-specific Plaque Hypothesis:

A

The non-specific plaque hypothesis: The microbes in MDP cause caries.

  • Biofilm (MDP)-mediated disease – Polymicrobial infection

The specific plaque hypothesis

Some microbial species in MDP cause caries. The cariogenic bacteria infect and increase in number in caries-active subjects.

  • Certain species of the microbial community play major role in the disease process - Oligomicrobial infection
162
Q

Hypotheses For the etiology of caries:

The ecological plaque hypothesis:

A

Various microbial species that are acidogenic and acid tolerant increase in number in MDP due to allogenic succession. MDP becomes more cariogenic.

  • The numbers of acidogenic and acid tolerant microbes increase in dental plaque due to microbial selection.
163
Q

Hypotheses For the etiology of caries:

The Extended Ecological Plaque Hypothesis:

A

The acidogenicity and acid tolerance of plaque increase due to microbial selection and adaptation.

164
Q

Hypotheses For the etiology of caries:

The Hypothesis of Autoinducer 2 – Autogenic Succession:

A

Another “ecological plaque hypothesis”

  • Increased concentration of Autoinducer 2 favors transition and growth of pathogenic (cariogenic) bacteria.
165
Q

MDP Catabolism and Dental Caries:

A

Twenty minutes after sugar intake, the MDP of cariesactive subjects has:

  • lactate >3 mM
  • pH <5.7
  • Increased acidogenic potential
  • Longer demineralization period

Dentistry-5th semester (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions