Chapter 5 Flashcards
Definition of bond or bonding
to connect or fasten; to bind. Items are jointed together at the surface in three main ways: mechanical adhesion, chemical adhesion, combination of the two
Definition of adhesion
the act of sticking two things together; describe the bonding or cementation process.
Definition of chemical adhesion
atoms or molecules of dissimilar substances bond together
Definition of cohesion
attraction among atoms and molecules of like (similar) materials holds them together
Definition of etching or conditioning
terms used interchangeably to describe the process of preparing the surface of a tooth or restoration for bonding. most common etching material (etchant) is phosphoric acid
Definition of cure or polymerization
a reaction that links low molecular weight resin molecules (monomers) together into high molecular weight chains (polymers) that harden or set.
can be initiated by strictly a chemical reaction (self-cure), light in the blue wave spectrum (light cure), or by a combination of two (dual cure), or heat
Definition of wetting
ability of a liquid to wet or intimately contact a solid surface.
Definition of wet dentin bonding
bonding to dentin that is kept moist after acid etching to facilitate penetration of bonding resins into etched dentin
Definition of smear layer
tenacious layer of debris on the dentin surface resulting from cutting the tooth during cavity preparation
Definition of bonding agent
low-viscosity resin that penetrates porosities and irregularities in the surface of the tooth or restoration created by acid etching for the purpose of facilitating bonding
Definition of hydrophilic
allows a material to tolerate the presence of moisture
Definition of hydrophobic
does not allow a material to tolerate or perform well in the presence of moisture
Definition of total etch system
bonding system that includes etching of both enamel and dentin as a separate step from the application of binding agents
Definition of self-etch system
bonding system that does not use a separate etching procedure with phosphoric acid. no rinsing needed
Definition of hybrid layer
resin/dentin layer formed by intermixing of the dentin bonding agent with collagen fibrils exposed by acid etching. serves as an excellent resin-rich layer onto which the restorative material can be bonded
Definition of microleakage
leakage of fluid in the microscopic gap of the restoration margin as a result of differences in expansion and contraction rates of the tooth and the restoration with temperature changes
Definition of percolation
movement of fluid in the microscopic gap of the restoration margin as a result of differences in expansion and contraction rates of the tooth and the restoration with temperature changes
Definition of hydrodynamic theory of tooth sensitivity
pain caused by movement of pulpal fluid in open (unsealed) dentinal tubules.
Definition of contamination
contact with a substance that changes the chemical or mechanical properties
What is preparation of the tooth surface?
removing plaque and debris, then etching or conditioning the enamel or dentin with an acid
What is the most commonly used acid?
phosphoric acid ranging from 10% - 38%
What does acid do?
removes mineral from the surface to create roughness or microscopic porosity
What happens when a resin bonding agent or primer is hardened?
cures or polymerizes which creates projections called resin tags that lock into the tooth creating a mechanical bond called micro mechanical retention
True or False
The chemical bond is stronger than a physical bond
True (physical bond called a secondary bond which is a weak interaction between two surfaces )
True or False
acid etch increases the ability of liquids to wet the surface of the tooth by creating high surface energy
True (however, high surface can also attract contaminates, so good isolation is important)
True or False
Surfaces that are poorly wet will cause beading of liquid
True
True or False
Bonding agents are usually not very viscous (thick) so they will flow readily and wet the etch surface
True
Most bond tests pull the bonded materials apart (tensile strength) or apply forces at approximately 90 degrees to the interface, until the bond fails (sheer bond strength)
True
What is the value for the bond strength?
megaPascals (1 mPa = 150 psi)
Bonding to enamel usually achieves how many mPa?
30 (4500 psi)
How long is the enamel of permeant teeth usually etched for?
20 - 30 seconds with 37% phosphoric acid
What is the mineral component of enamel?
hydroxyapatite
What is the smear layer composed of?
cut tooth structure, plaque, bacteria, pellicle, saliva, blood
2 micrometers thick
True or False
Over-etching will expose too much collagen matrix, causing it to act as a thick barrier and making it more difficult to coat the dentin with bonding agents
True
True or False
The dentin surface must be kept moist to keep collagen fibrils fluffed up
True (if over-dried collagen fibrils collapse and form a dense surface that occludes tubules and blocks dentin bonding resins)
If enamel becomes contaminated after etching, how long must it be re-etched for?
10-15 seconds before bonding process is continued
What are solvents primarily made of?
acetone, ethanol, combination of ethanol and water
