Pathway 14-7 Pulp Reactions to Restorative Materials

Study Notes

The permeability of dentin is a key factor in pulp reactions to restorative materials.
Dentin thickness between the cavity preparation and the pulp is the most important variable in dentin permeability.
Dentin permeability can be influenced by age and caries status.

Unbound components of resin materials and preparative agents can induce an inflammatory response in the pulp.
Resin monomers (e.g., triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate) penetrate dentin and can affect the pulp.
Eugenol and components of Ledermix (triamcinolone and demeclocycline) can also pass through dentin and affect the pulp.
Cytotoxic components of resin restorations can lead to chronic stimulation and a prolonged inflammatory response.
Subtoxic concentrations of certain agents can trigger allergic reactions in humans.
Foreign body reactions can occur with extruded globules of resin material, leading to macrophage and giant cell formation.
Resin monomers can decrease the activity of immunocompetent cells in a dose-dependent manner.

Desiccation and demineralization of dentin can contribute to pulp irritation.
Technique sensitivity of certain materials can lead to faulty bonds and subsequent dentin hypersensitivity, recurrent disease, and pulp inflammation.
Dry preparation surfaces can result in defective bonds, particularly with resin-bonded materials.

Calcium hydroxide is used to stimulate dentinal bridge formation in pulp exposures.
It induces a low-grade pulp irritation, which is necessary for dentin bridge formation.
Aqueous suspensions of calcium hydroxide cause superficial necrosis of pulp tissue followed by low-grade inflammatory changes.
Hard-setting calcium hydroxide preparations and mineral trioxide aggregates (MTAs) elicit dentin bridge formation with minimal to no necrotic zone.
Calcium hydroxide application to intact dentin promotes sclerosis by promoting crystal precipitation within dentinal tubules, reducing permeability.
Calcium hydroxide and MTA liberate bioactive molecules from dentin, such as TGF-β1 and adrenomedullin, facilitating hard tissue formation.
Acid etching and chelating agents (e.g., EDTA) can also liberate bioactive molecules from dentin, including growth factors and metalloproteinases.
Glass ionomers can damage pulp tissues due to their lowered pH and release of high concentrations of fluoride.
Glass ionomers are toxic to pulp cells in direct contact, but can induce reparative dentin formation when applied to intact dentin.

Zinc oxide and eugenol (ZOE) have anesthetic and antiseptic properties.
ZOE can block action potentials in nerve fibers, suppress nerve excitability in the pulp, and inhibit bacterial growth.
ZOE is often used for temporary fillings due to its short-term effectiveness.

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