Dental Resin Composites Eluates

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Questions and Answers

What is the main factor that influences the composition of eluates from resin-based composites?

Type of light-curing

Method of polymerization

Extraction medium and composition of the resin-based composite (correct)

Type of filler particles

Which substance is typically the most abundant in the eluates from resin-based composites?

TEGDMA (correct)

Bis-EMA

MMA

Bis-GMA

What is the primary source of silicon, boron, sodium, and barium in eluates from resin-based composites?

Filler particles (correct)

Polymerization byproduct

Resin matrix

Extraction medium

What is a condition under which formaldehyde is likely to be released from resin-based composites into water?

When the superficial oxygen-inhibited surface layer is not removed Signup and view all the answers

What is a likely mechanism for the generation of formaldehyde from resin-based composites?

Oxidation of unsaturated methacrylate groups Signup and view all the answers

What was found in the extract of one pit and fissure sealant and in saliva in contact with resin-based composites?

BPA Signup and view all the answers

What was the criticism of the analytical technique used to detect BPA in resin-based composites?

Methodological problems Signup and view all the answers

What was the finding of studies on the release of BPA from resin-based composites?

Only trace amounts of BPA were detected Signup and view all the answers

What is one of the causes of pulp reaction after application of a resin-based composite or adhesive?

Bacteria at the cavity floor Signup and view all the answers

What is the prerequisite for bacterial colonization of the cavity floor?

Gap between the filling and the cavity wall Signup and view all the answers

What is the main difference between resin-based composite fillings and amalgam fillings in terms of bacterial growth?

Resin-based composite fillings have up to eight times more microorganisms Signup and view all the answers

Why may bacteria that are present beneath a composite resin filling cause a pulpal reaction?

Because the amount of segregated bacterial toxins increases with time Signup and view all the answers

What can help decrease the marginal gap in difficult-to-access cavities?

Adhesives Signup and view all the answers

Why may problems arise in applying the adhesive technique?

If the cavity margins are located in dentin/cementum Signup and view all the answers

What can provide sufficient protection for the pulp in medium cavities?

The dentin barrier Signup and view all the answers

What decreases over time due to the setting reaction of materials?

The release of leachables from materials Signup and view all the answers

What is the primary purpose of applying a “sealing” adhesive?

To prevent further penetration of bacteria into the dentinal tubulus Signup and view all the answers

What is the primary difference between Bis-DMA and Bis-GMA-based pit and fissure sealants?

Amount of BPA released into saliva Signup and view all the answers

What is the size range of particles produced during grinding and polishing of composite resin fillings?

0.5–10-μm Signup and view all the answers

According to Fung et al.'s study, what was the detection limit for BPA in blood samples?

5 ppb Signup and view all the answers

What is the recommended method to prevent inhalation during grinding and shaping of composite resin restorations?

Using a suction and water spray Signup and view all the answers

What is the primary reason for the release of BPA from Bis-DMA-based pit and fissure sealants?

Initial elution of Bis-DMA followed by degradation to BPA Signup and view all the answers

What is the main difference in fluoride release between resin-based composites and conventional glass ionomer cements?

Amount of fluoride released Signup and view all the answers

What is the temperature rise associated with the polymerization of a resin and the thermal radiation of a curing unit?

5.5 °C Signup and view all the answers

What is the documented effect of an increase of 5.5 °C of the temperature in the pulp?

Irreversible pulpal damage in 15% of all cases Signup and view all the answers

What is the expected caries-prophylactic benefit of resin-based composites and compomers?

Liberation of calcium and hydroxyl ions Signup and view all the answers

What happens to swallowed HEMA/TEGDMA in the organism?

It is almost completely absorbed by the organism Signup and view all the answers

What is the temperature increase in the material during the exothermal setting reaction of resin-based composite?

Up to 12.0 °C Signup and view all the answers

What is the temperature rise found in resin-based composite when a QTH curing unit is used?

15.5–18.6 °C Signup and view all the answers

What is the common property of HEMA and TEGDMA?

Water-soluble Signup and view all the answers

What is the primary use of Bis-DMA and Bis-GMA?

In pit and fissure sealants Signup and view all the answers

What is the advantage of using an LED unit compared to a QTH curing device?

Lower temperature increase Signup and view all the answers

What is a key factor that contributes to the inefficiency of quartz tungsten halogen (QTH) light curing units?

The requirement for absorbing filters Signup and view all the answers

What is a characteristic of light-emitting diode (LED) light curing units?

They emit a specific range of energy due to the semiconductor material Signup and view all the answers

Why does the temperature rise during photoactivation decrease significantly with increasing dentin thickness?

Because dentin is an excellent thermal insulator Signup and view all the answers

What is the consequence of insufficient curing depth in dental composites?

Release of residual monomers or cytotoxic substances into the oral cavity Signup and view all the answers

What determines the depth of cure of a dental composite?

The thickness of the material that can be adequately polymerized Signup and view all the answers

What can uncured or partially cured resin in dental composites provoke?

An inflammatory response or cytotoxic effects Signup and view all the answers

Why are light-emitting diodes (LED) considered a viable alternative to quartz tungsten halogen (QTH) light curing units?

Because they are more efficient and produce less heat Signup and view all the answers

What is the primary goal of achieving adequate curing depth in dental composites?

To achieve the intended mechanical and physical properties Signup and view all the answers

Study Notes

Composition of Eluates

34 individual compounds can be released from resin-based composites, including Bis-GMA, Bis-EMA, UDMA, TEGDMA, EGDMA, and methylmethacrylate (MMA)
TEGDMA generally represents the major share of the segregated substances
Silicon, boron, sodium, and barium can leach from filler particles into water, depending on the filler type

Release of Substances

Formaldehyde can be released from resin-based composites into water under certain circumstances
Formaldehyde is likely generated by oxidation of unsaturated methacrylate groups during polymerization or as a degradation product of the oxygen-inhibited surface layer
Bisphenol A (BPA) was found in the extract of one pit and fissure sealant and in saliva in contact with resin-based composites
However, other studies found only trace amounts of BPA in unpolymerized resin-based composites or no BPA release after testing 24 different resin-based composite products

Fluoride Release

Fluoride is released from fluoride-containing resin-based composites and compomers, but the released quantity dramatically decreases after a 24-h elution
The total segregated amount is smaller than from conventional or light-curable glass ionomer cements
Calcium and hydroxyl ions are also released due to the addition of adequate glasses, which may have a caries-prophylactic effect

Biodegradation of Monomers

HEMA/TEGDMA are "water-soluble" substances used in resin-based composites and adhesives, and are almost completely absorbed by the organism
Bacteria at the cavity floor can cause a pulp reaction even in shallow or medium cavities, where no direct chemical-toxic effect of substances leaching from composites or adhesives is expected

Bacteria at the Cavity Floor

Bacteria that are present beneath a composite resin filling may cause a pulpal reaction
The release of leachables from materials decreases over time, and the dentin barrier may provide sufficient protection for the pulp
However, bacteria proliferate, and the amount of segregated bacterial toxins will increase with time

Inhalation of Resin-Based Composite Particles

Particles in the 0.5–10-μm size range may be produced during grinding and polishing of composite resin fillings
Inhalation of such particles may lead to foci of chronic lung inflammation around these particles
Prevention measures include using a rubber dam or suction and water spray during grinding and shaping of composite resin restorations

Thermal Effects of Light-Curing Units

Temperature rise may be associated with polymerization of a resin and the thermal radiation of a curing unit
A temperature rise of 5.5 °C in the pulp will cause irreversible pulpal damage in 15% of all cases
The exothermal setting reaction of resin-based composite causes a temperature increase in the material of up to 12°C within 10 s
The additional temperature increase due to the curing light unit occurs continuously during the entire irradiation period

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Description

This quiz assesses your understanding of the composition of eluates from resin-based composites, including the types of compounds released and the extraction medium used. Learn about the individual compounds and their proportions in the segregated substances.