Demineralized dentin 3D porosity and pore size distribution using mercury porosimetry.
OBJECTIVE
The objectives of this study were to assess demineralized dentin porosity and quantify the different porous features distribution within the material using mercury intrusion porosimetry (MIP) technique. We compared hexamethyldisilazane (HMDS) drying and lyophilization (LYO) (freeze-drying) in sample preparation.


METHODS
Fifty-six dentin discs were assigned into three groups. The control (CTR) group discs were superficially acid-etched (15s 37% H(3)PO(4)) to remove the smear layer and then freeze-dried whereas LYO and HMDS groups samples were first totally demineralized using EDTA 0.5M and then freeze-dried and HMDS-dried respectively. MIP was used to determine open porosity and pore size distribution of each pair of samples. Field emission scanning electron microscopy (FESEM) was used to illustrate the results.


RESULTS
The results showed two types of pores corresponding either to tubules and micro-branches or to inter-fibrillar spaces created by demineralization. Global porosity varied from 59% (HMDS-dried samples) to 70% (freeze-dried samples). Lyophilization drying technique seems to lead to less shrinkage than HMDS drying. FESEM revealed that collagen fibers of demineralized lyophilized samples are less melted together than in the HMDS-dried samples.


CONCLUSIONS
Demineralized dentin porosity is a key parameter in dentin bonding that will influence the hybrid layer quality. Its characterization could be helpful to improve the monomers infiltration.
Vennat
Elsa
E
Laboratoire Mécanique des Sols, Structures et Matériaux, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Chatenay Malabry Cedex, France. elsa.vennat@ecp.fr
Bogicevic
Christine
C
Fleureau
Jean-Marie
JM
Degrange
Michel
M
D003804:Dentin / Q000473:pathology* / Q000648:ultrastructure; D003806:Dentin Permeability; D003890:Desiccation / Q000379:methods*; D024022:Fibrillar Collagens / Q000648:ultrastructure; D005404:Fixatives; D005612:Freeze Drying; D006801:Humans; D008628:Mercury; D008855:Microscopy, Electron, Scanning; D017646:Organosilicon Compounds; D016062:Porosity; D017001:Tooth Demineralization / Q000473:pathology*
D024022:Fibrillar Collagens; D005404:Fixatives; D017646:Organosilicon Compounds; D008628:Mercury; C024548:hexamethylsilazane