Mechanical properties and biochemical activity of remineralizing resin-based Ca-PO4 cements.
OBJECTIVE
This study examined strength and bioactive (remineralizing) properties of a powder/liquid formulation (Cement I) and a more practical two-paste formulation (Cement II) of a fluoride-releasing resin-based Ca-PO(4) cement.


METHODS
For the remineralization potential, the dissolution of calcium, total ionic phosphate and fluoride from set cement specimens were determined in buffered saline and saliva-like solution (SLS). Artificial caries lesions were produced on coronal dentin of extracted human molars. On each tooth, two defined areas were coated, one with a composite resin (calcium-free control), the other with either Cement I or II. After incubation in SLS, the mineral loss under the cement was analyzed by digitized microradiography and compared to that under the control.


RESULTS
The diametral tensile strength of Cement II of approximately 30 MPa after 24 h and 23 MPa after 4 weeks was 2 to 3 times higher than that of Cement I (ANOVA, t-test, p<0.05). Calculations of the ion-activity products and Gibb's free energy from solution ion concentrations indicated a significant potential for the formation of fluor- and/or hydroxyapatite. Concurrently, both cements caused increases of 47% (Cement I) and 38% (Cement II) in the lesion mineral content over that underneath the corresponding controls.


CONCLUSIONS
These in vitro results suggest that the stronger Cement II could serve as a restoration-supporting lining material and could remineralize dentin in areas where complete removal of carious tissue is contra-indicated.
Dickens
Sabine H
SH
American Dental Association Health Foundation, National Institute of Standards and Technology, Paffenbarger Research Center, 100 Bereau Dr Stop 8546, Gaithersburg, MD 20899-8546, USA. sabine.dickens@nist.gov
Flaim
Glenn M
GM
Takagi
Shozo
S
D001031:Apatites / Q000493:pharmacokinetics; D002130:Calcium Phosphates / Q000737:chemistry / Q000493:pharmacokinetics*; D003736:Dental Cavity Lining; D003804:Dentin / Q000378:metabolism; D017886:Durapatite / Q000493:pharmacokinetics; D005459:Fluorides / Q000493:pharmacokinetics; D006801:Humans; D008422:Materials Testing; D008963:Molar; D019279:Resin Cements / Q000737:chemistry*; D013718:Tensile Strength; D014089:Tooth Remineralization
D001031:Apatites; D002130:Calcium Phosphates; D019279:Resin Cements; D017886:Durapatite; C025105:fluorapatite; D005459:Fluorides