TY - JOUR
T1 - Reactivation of inactivated endogenous proteolytic activities in phosphoric acid-etched dentine by etch-and-rinse adhesives
AU - Mazzoni, Annalisa
AU - Pashley, David H.
AU - Nishitani, Yoshihiro
AU - Breschi, Lorenzo
AU - Mannello, Ferdinando
AU - Tjäderhane, Leo
AU - Toledano, Manuel
AU - Pashley, Edna L.
AU - Tay, Franklin R.
N1 - Funding Information:
This study was based on the dissertation to be submitted by Annalisa Mazzoni to the University of Bologna, Italy for partial fulfilment of the degree of Doctor of Philosophy. The authors graciously acknowledge the generous gifts of the adhesives from 3M ESPE, Bisco, Inc., Dentsply DeTrey, Ivoclar-Vivadent and Sybron-Kerr (in alphabetical order). This work was funded by grants R01 DE014911 and R01 DE015306 from the National Institute of Dental and Craniofacial Research, Bethesda, MD (P.I.D. Pashley), and by the Academy of Finland (Grant 104377, P.I.L. Tjäderhane). The authors are grateful to Penny Roon for technical assistance with the transmission electron microscope and to Michelle Barnes for secretarial assistance.
PY - 2006/9
Y1 - 2006/9
N2 - Auto-degradation of collagen matrices occurs in resin-infiltrated dentine by the slow action of host-derived matrix metalloproteinases. As phosphoric acid-etching inactivates these endogenous enzymes, it is puzzling how hybrid layers created by simplified etch-and-rinse adhesives can degrade in vivo. This study tested the null hypothesis that there are no differences in the relative proteolytic activities of mineralised dentine, acid-etched dentine, and etch-and-rinse adhesivetreated acid-etched dentine. Powdered dentine prepared from extracted human teeth was treated with 17% EDTA, 10% phosphoric acid, or with five simplified etch-and-rinse adhesives that were applied to 10% phosphoric acid-etched dentine. The gelatinolytic activity of the dentine powder was assayed using fluorescein-labelled gelatine. TEM examination of the air-dried, treated dentine powder was performed to confirm the presence of remnant mineralised dentine after acid-etching. 17% EDTA significantly reduced the relative proteolytic activity (73.2%) of the untreated mineralised dentine powder (control), while 10% phosphoric acid-etched dentine exhibited the highest reduction (98.1%). Treating the acid-etched dentine powder with any of the five simplified etch-and-rinse adhesives resulted in the reactivation of the proteolytic activity, with a significant negative linear correlation ( P < 0.05) between the increases in fluorescence and the corresponding pH values of the adhesives. It is concluded that simplified etch-and-rinse adhesives can reactivate endogenous enzymatic activities in dentine that are previously inactivated by phosphoric acid-etching. The amount of enzyme reactivated may even exceed the original quantity present in untreated mineralised dentine. This provides an explanation for the degradation of hybrid layers after acid-etched dentine matrices are infiltrated with these adhesives.
AB - Auto-degradation of collagen matrices occurs in resin-infiltrated dentine by the slow action of host-derived matrix metalloproteinases. As phosphoric acid-etching inactivates these endogenous enzymes, it is puzzling how hybrid layers created by simplified etch-and-rinse adhesives can degrade in vivo. This study tested the null hypothesis that there are no differences in the relative proteolytic activities of mineralised dentine, acid-etched dentine, and etch-and-rinse adhesivetreated acid-etched dentine. Powdered dentine prepared from extracted human teeth was treated with 17% EDTA, 10% phosphoric acid, or with five simplified etch-and-rinse adhesives that were applied to 10% phosphoric acid-etched dentine. The gelatinolytic activity of the dentine powder was assayed using fluorescein-labelled gelatine. TEM examination of the air-dried, treated dentine powder was performed to confirm the presence of remnant mineralised dentine after acid-etching. 17% EDTA significantly reduced the relative proteolytic activity (73.2%) of the untreated mineralised dentine powder (control), while 10% phosphoric acid-etched dentine exhibited the highest reduction (98.1%). Treating the acid-etched dentine powder with any of the five simplified etch-and-rinse adhesives resulted in the reactivation of the proteolytic activity, with a significant negative linear correlation ( P < 0.05) between the increases in fluorescence and the corresponding pH values of the adhesives. It is concluded that simplified etch-and-rinse adhesives can reactivate endogenous enzymatic activities in dentine that are previously inactivated by phosphoric acid-etching. The amount of enzyme reactivated may even exceed the original quantity present in untreated mineralised dentine. This provides an explanation for the degradation of hybrid layers after acid-etched dentine matrices are infiltrated with these adhesives.
KW - Acid-etched dentine
KW - Collagen degradation
KW - Etch-and-rinse adhesives
KW - Fluorescence
KW - Fluorometric enzymatic assay
KW - Proteolytic activity
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U2 - 10.1016/j.biomaterials.2006.01.040
DO - 10.1016/j.biomaterials.2006.01.040
M3 - Article
C2 - 16687171
AN - SCOPUS:33747357877
SN - 0142-9612
VL - 27
SP - 4470
EP - 4476
JO - Biomaterials
JF - Biomaterials
IS - 25
ER -