Direct Restorative Materials Adhesive Systems and Mechanical Properties

A set of vocabulary flashcards detailing dental adhesive systems, generations, surface preparation techniques, and mechanical/physical material properties based on lecture notes.

Dr. Michael Buonocore

The researcher who in 1955 introduced acid etching with phosphoric acid to improve the adhesion of restorative materials to teeth.

Bis-GMA

Bisphenol A-glycidyl methacrylate, introduced by Dr. Rafael Bowen in 1962, which forms a durable and aesthetic restorative material when combined with silane-coupled inorganic filler.

Smear Layer

A $1\text{--}5\,\mu\text{m}$ thick surface layer composed of mineralized collagen debris, hydroxyapatite, dentine proteins, bacteria, and saliva produced during tooth preparation.

Acid Etching

The application of $35\text{--}37\%$ phosphoric acid to fully remove the smear layer and create microporosities by demineralizing tooth structure to enable mechanical micro-retention.

Tooth Conditioning

The application of $10\text{--}20\%$ polyacrylic acid to modify the smear layer without destroying tooth structure, making it permeable to resin interaction.

Type I Etching Pattern

An enamel etching pattern characterized by the dissolution of the prism core, resulting in a honeycomb appearance.

Type II Etching Pattern

An enamel etching pattern characterized by the dissolution of the prism periphery, resulting in a cobblestone-like appearance.

Adhesive Failure

An enamel bonding failure occurring specifically at the interface between the tooth structure and the resin, often caused by surface contamination prior to placement.

Cohesive Failure

An enamel bonding failure that occurs within the material itself, such as within the luting cement or the adhesive resin.

Beveling

Creating a sloped or slanted surface on enamel margins to remove unsupported enamel, increase available bonding surface area, and improve aesthetic blending.

Hybrid Layer

A $2\text{--}10\,\mu\text{m}$ thick resin-infiltrated collagenous network formed by dentine structure, exposed collagen, hydroxyapatite, and primer.

C-Factor (Configuration Factor)

The ratio of bonded surfaces to unbonded surfaces in a cavity preparation; higher ratios increase stress on bonds due to restricted polymerization shrinkage flow.

2% Chlorhexidine

A solution applied for approximately 60 seconds after acid etching to inhibit matrix metalloproteinases (MMPs), prevent collagen fiber degradation, and enhance bond longevity.

Bifunctional Monomer

A molecule containing two distinct functional groups: a hydrophilic group that bonds to hydroxyapatite and collagen, and a hydrophobic methacrylate group that bonds to restorative resin.

10-MDP Monomer

10-methacryloxydecyl dihydrogen phosphate, a phosphoric acid ester monomer that chemically bonds to calcium in hydroxyapatite and metals while preserving collagen by inhibiting MMP activity.

Bond (Sealer)

An unfilled or low-filled resin (e.g., Bis-GMA, HEMA) applied after priming to flow easily into surface irregularities and open dentinal tubules.

4th Generation Adhesive System

A three-bottle, etch-and-rinse (total-etch) system requiring separate acid etching, primer application, and bonding agent application (e.g., OptiBond FL).

5th Generation Adhesive System

A two-bottle, etch-and-rinse system that combines the primer and bonding agent into a single bottle following a separate acid etching step (e.g., Optibond Solo Plus).

6th Generation Adhesive System

A two-bottle self-etching system that utilizes a self-etching primer (no rinsing required) followed by a separate bonding agent (e.g., Clearfil SE Bond 2).

7th Generation Adhesive System

A single-bottle self-etching system that combines etch, prime, and seal functions in one bottle without requiring rinsing or mixing (e.g., Scotchbond Universal).

8th Generation (Universal) Adhesive System

A single-bottle multi-modal self-etching system containing 10-MDP, silane, and nano-fillers designed for both direct and indirect bonding procedures.

Sclerotic Dentine

Highly mineralized, fluoride-rich dentine featuring insoluble crystals and irregular collagen that is resistant to acid etching, often requiring surface modification like sandblasting.

Deep Dentine

Dentine located near the pulp characterized by wider, more numerous tubules, less intertubular dentine, and higher moisture content, making bonding challenging.

Static Strength

The ability of a material to resist mechanical deformation or failure under an immediate, short-term, steady force or load.

Creep Strength

The mechanical ability of a material to resist deformation under a load applied continuously over an extended duration.

Fatigue Strength

The ability of a material to withstand repetitive, cyclic loading and unloading forces without structural failure.

Tensile Load

Mechanical forces that attempt to pull a material apart or stretch it along its axis.

Compressive Load

Mechanical forces that attempt to squeeze, crush, or compress a material lengthwise.

Shear Load

Forces applied at different angles or directions that attempt to slide one portion of a material across another.

Stress ($\sigma$)

The internal force acting per unit cross-sectional area of a material ($\text{Stress} = F/A = \sigma$), expressed in Pascals ($\text{N/m}^2$) or Megapascals ($\text{MPa}$).

Strain ($e$ or $\epsilon$)

The fractional or proportional change in dimensions experienced by a material as a result of applied stress ($\text{Strain} = (L_1 - L_0)/L_0$).

Elastic Modulus ($E$)

The slope of the linear region on a stress-strain curve ($E = \sigma / e$), representing a material's stiffness.

Proportional Limit

The specific point on a stress-strain curve where stress and strain cease to maintain a linear proportional relationship.

Elastic Limit

The maximum stress value that can be applied to a material without causing permanent plastic deformation.

Resilience

The amount of energy a material can absorb without permanent deformation, measured as the area under the stress-strain curve up to the elastic limit.

Ultimate Tensile Strength

The maximum stress coordinate on a stress-strain curve that a material can withstand before necking or localized thinning begins.

Fracture Strength

The specific stress value at which a material completely snaps or breaks apart.

Toughness

The total energy a material can absorb before it fractures, calculated as the total area under both the elastic and plastic regions of the stress-strain curve.

Ductility

The length of the plastic deformation region along the x-axis of a stress-strain curve, indicating how much a material can be stretched without breaking.

Diametral Tensile Strength Test

A test in which a disc-shaped specimen is compressed sideways to convert applied compressive force into lateral tensile stress, used for testing brittle materials.

Flexural Strength Test

A test measuring a material's ability to resist deformation under a load when supported at two points as a beam, creating top compressive stress and bottom tensile stress.

Stress Concentration

A localized region within a restoration (such as around holes, cracks, or sharp internal angles) where internal mechanical stress is significantly magnified.