pH changes of self-etching primers mixed with powdered dentine.
OBJECTIVE
The purpose of this study was to examine the pH changes of self-etching primers mixed with dentine powder.


METHODS
Four self-etching primer adhesive systems were used: Clearfil SE Bond, Imperva Fluoro Bond, Mac Bond II, and Unifil Bond. Dentine discs obtained from extracted bovine incisors were milled and pulverized into a fine powder. The dentine powder was then mixed with solutions of self-etching primers diluted with distilled water. The pH changes of the primer-dentine powder mixtures were measured by a solid-state pH sensor connected to a pH meter at time points 10, 20, 30, 60, 120, 180, 300, and 600 s after the start of mixing. Data were analyzed by the Tukey HSD test and the Dunnett test at a significance level of 0.05.


RESULTS
The baseline pH values of the self-etching primers ranged from 1.83 to 2.34, with Mac Bond II exhibiting a significantly lower value than the other three products. After mixing with the dentine powder, the pH values significantly increased, ranging from 6.95 to 7.37 at 600 s after mixing; there were no significant differences in these values among the self-etching primers used. An insoluble precipitate was formed in the case of Clearfil SE Bond, indicating a chemical reaction between the functional monomer and the dentine powder.


CONCLUSIONS
The dentine has a strong buffering capacity against the acidity of self-etching primers.
Maeda
T
T
Nihon University School of Dentistry, Department of Operative Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-Ku, Tokyo, Japan.
Yamaguchi
K
K
Takamizawa
T
T
Rikuta
A
A
Tsubota
K
K
Ando
S
S
Miyazaki
M
M
D000818:Animals; D002021:Buffers; D002417:Cattle; D011232:Chemical Precipitation; D003804:Dentin / Q000737:chemistry / Q000502:physiology*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D011208:Powders; D019279:Resin Cements / Q000737:chemistry; D012995:Solubility; D013997:Time Factors; D014867:Water / Q000737:chemistry
D002021:Buffers; C438313:Clearfil SE Bond; D017220:Dentin-Bonding Agents; C452442:Mac Bond II; D011208:Powders; D019279:Resin Cements; C407402:Unifil Bond; C474103:imperva fluoro bond; D014867:Water