The effect of dentin water concentration on host-derived enzymatic degradation of dentin matrix
Nokkala, Markus (2019-01-18)
The effect of dentin water concentration on host-derived enzymatic degradation of dentin matrix
(18.01.2019)
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
suljettu
Julkaisun pysyvä osoite on:
https://urn.fi/URN:NBN:fi-fe201901253077
https://urn.fi/URN:NBN:fi-fe201901253077
Tiivistelmä
Objective: Enzymatic degradation of the collagen matrix of dentin by host-derived enzymes plays a significant role in the destruction of resin-dentin bonds. Endogenous proteases are hydrolyses that require water for their activities. The objective of the present study was to determine the effects of water concentration on the hydrolase activity of demineralized dentin matrices.
Methods: Dentin powder was prepared from coronal dentin of sound third molars and demineralized in 10% H3PO4 for 8 h. Demineralized dentin powder was divided into ten groups and incubated for 1 week at 37 °C in pure water (controls) or in ethanol/water mixtures that stepwise lowered the water concentration to zero (25, 50, 75, 87.5, 93.75, 96.8, 100% ethanol). Three separate measures of degradation of demineralized dentin matrices were measured: Collagen solubilization by hydroxyproline assay, and CTX and ICTP telopeptide release, by peptide-specific ELISAs.
Results: Solubilization of matrix collagen ceased when the media water concentration fell below 50 vol %. Both CTX and ICTP telopeptides were released at high water concentrations, but fell when the water concentration fell below 50 vol %. At water concentrations of 25 vol % or lower, hydrolases fell to near zero. Optimum hydrolase activity required at least 25 vol % water.
Significance: The residual water content of dentin hybrid layers is the sum of the water content of the etched dentin, the water content of the applied adhesive, the amount of water evaporated before light-curing, and the amount of water that transudates from underlying dentin into the hybrid layer via dentinal tubules, pre- and post- bonding. Residual water in hybrid layerscan be lowered during bonding by dilution with water- miscible solvents. In hybrid layers created by etch-and-rinse adhesives, water in underlying dentinal tubules may slowly transudate into uninfiltrated regions, where it can fuel matrix degradation by endogenous hydrolases.
Methods: Dentin powder was prepared from coronal dentin of sound third molars and demineralized in 10% H3PO4 for 8 h. Demineralized dentin powder was divided into ten groups and incubated for 1 week at 37 °C in pure water (controls) or in ethanol/water mixtures that stepwise lowered the water concentration to zero (25, 50, 75, 87.5, 93.75, 96.8, 100% ethanol). Three separate measures of degradation of demineralized dentin matrices were measured: Collagen solubilization by hydroxyproline assay, and CTX and ICTP telopeptide release, by peptide-specific ELISAs.
Results: Solubilization of matrix collagen ceased when the media water concentration fell below 50 vol %. Both CTX and ICTP telopeptides were released at high water concentrations, but fell when the water concentration fell below 50 vol %. At water concentrations of 25 vol % or lower, hydrolases fell to near zero. Optimum hydrolase activity required at least 25 vol % water.
Significance: The residual water content of dentin hybrid layers is the sum of the water content of the etched dentin, the water content of the applied adhesive, the amount of water evaporated before light-curing, and the amount of water that transudates from underlying dentin into the hybrid layer via dentinal tubules, pre- and post- bonding. Residual water in hybrid layerscan be lowered during bonding by dilution with water- miscible solvents. In hybrid layers created by etch-and-rinse adhesives, water in underlying dentinal tubules may slowly transudate into uninfiltrated regions, where it can fuel matrix degradation by endogenous hydrolases.