Acidity of conventional luting cements and their diffusion through bovine dentine.
OBJECTIVE
To examine the changes in pH of luting cements and acid diffusion of luting cements through bovine dentine using a pH-imaging microscope (SCHEM-100; Horiba Ltd, Kyoto, Japan).


METHODS
The pH of the surface of three conventional luting cements, glass-ionomer, zinc phosphate and zinc polycarboxylate was measured with SCHEM-100 for 1 month. The acid diffusion from the three luting cements through bovine dentine was investigated by measuring pH changes during the application of each luting cement on the bovine dentine surface. Coronal bovine dentine disks were prepared to thicknesses of 0.50 and 0.25 mm. Each luting cement was placed on the labial dentine surface, and the pH change of the pulpal surface was observed every 3 min for 30 min with SCHEM-100.


RESULTS
Glass-ionomer showed the lowest pH values for longer times. Neutralization proceeded furthest in zinc polycarboxylate. The 0.5-mm-thick dentine disks showed no pH change on the pulpal side with all the three cements. The 0.25-mm-thick disks revealed evidence of acid diffusion on the pulpal side of the cemented dentine and significantly lower pH when cemented with glass-ionomer and zinc phosphate than with zinc polycarboxylates.


CONCLUSIONS
This study demonstrated that glass-ionomer exhibited a lower setting pH than zinc phosphate and zinc polycarboxylate, and acid diffusions from glass-ionomer and zinc phosphate cements were observed when placed on 0.25-mm-thick dentine disks.
Hiraishi
N
N
Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, and R&D Center, Horiba Ltd, Kyoto, Japan. noricoh@aol.com
Kitasako
Y
Y
Nikaido
T
T
Foxton
R M
RM
Tagami
J
J
Nomura
S
S
D000143:Acids; D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D003738:Dental Cements / Q000737:chemistry*; D003804:Dentin / Q000033:anatomy & histology / Q000378:metabolism*; D004058:Diffusion; D005899:Glass Ionomer Cements / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008853:Microscopy; D011076:Polycarboxylate Cement / Q000737:chemistry; D013997:Time Factors; D015036:Zinc Phosphate Cement / Q000737:chemistry
D000143:Acids; D003738:Dental Cements; D005899:Glass Ionomer Cements; D011076:Polycarboxylate Cement; D015036:Zinc Phosphate Cement