Dentin: A dynamic substrate - A review

D. H. Pashley

Research output: Contribution to journalReview article

216 Citations (Scopus)

Abstract

The structure of dentin is unusual in that the number and size of its tubules changes as one moves from the periphery toward the pulp chamber. Near the pulp, the tubules are very close together and the water content of this deep dentin is high. Near the enamel, the tubules are far apart, occupying less than 1% of the surface area. When enamel or dentin is cut, the surface becomes covered by an adherent layer of cutting debris called the smear layer. Its composition presumably reflects the composition of the underlying dentin. It is only about 1 μm thick but its presence modifies the function of the dentin a great deal. It lowers dentin permeability and therefore can be regarded as protective. However, it masks the underlying dentin and hence interferes with attempts to bond dental materials directly to dentin. If it is removed, the dentin becomes much more permeable and fluid shifts across the open tubules can cause sensitivity in vivo. As smear layers are very acid-labile, they often dissolve in oral fluids. Several attempts have been made to repalce smear layers with acid resistant structures that accomplish the same function. Smear layer structure is being studied by using both scanning electron microscopy as well as electronic particle sizing equipment. The close adaptation of dental materials to smear layers and to underlying dentin is currently an area of very active research. Removal of smear layers increases adaptation and bonding strength but may increase the incidence of pulpal inflammation if the bonding is not uniform or permanent. The dynamics of dentin are just beginning to be understood.

Original languageEnglish (US)
Pages (from-to)161-176
Number of pages16
JournalScanning Microscopy
Volume3
Issue number1
StatePublished - Jan 1 1989

Fingerprint

Dental materials
Enamels
smear
Pulp
Fluids
Acids
Substrates
Chemical analysis
Debris
Water content
Masks
enamels
Scanning electron microscopy
acids
sizing
debris
moisture content
permeability
masks
incidence

ASJC Scopus subject areas

  • Instrumentation

Cite this

Pashley, D. H. (1989). Dentin: A dynamic substrate - A review. Scanning Microscopy, 3(1), 161-176.

Dentin : A dynamic substrate - A review. / Pashley, D. H.

In: Scanning Microscopy, Vol. 3, No. 1, 01.01.1989, p. 161-176.

Research output: Contribution to journalReview article

Pashley, DH 1989, 'Dentin: A dynamic substrate - A review', Scanning Microscopy, vol. 3, no. 1, pp. 161-176.
Pashley DH. Dentin: A dynamic substrate - A review. Scanning Microscopy. 1989 Jan 1;3(1):161-176.
Pashley, D. H. / Dentin : A dynamic substrate - A review. In: Scanning Microscopy. 1989 ; Vol. 3, No. 1. pp. 161-176.
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