Smear layer and surface state affect dentin fluoride uptake.
OBJECTIVE
Polishing generates a smear layer (SL) on in vitro dentin samples that may influence fluoride uptake. We tested two hypotheses: SL increases fluoride uptake in superficial dentin (H1) and decreases fluoride uptake in deeper layers (H2) irrespectively of the amount of fluoride administered.


METHODS
Polished bovine dentin with SL present and removed by four methods (5% tannic acid, 20s [TA]; 17% EDTA, 120 s; 38% phosphoric acid, 60s [PA]; and 10s air polishing) was fluoridated with 1200 or 12000 ppm F (NaF) solution (pH 4.0).


RESULTS
Scanning electron microscopy (SEM) revealed that aggressiveness of SL removal varied by method from leaving SL patches behind (TA) to collagen exposure (PA). SL increased KOH-soluble and structurally bound fluoride uptake into superficial and deeper layers compared to SL free surfaces (except PA) following 1200 ppm, but not 12000 ppm fluoridation.


CONCLUSIONS
Presence of SL and surface conditions influence dentin fluoride uptake depending on fluoride concentration administered.
Buchalla
W
W
Department for Preventive Dentistry, Periodontology and Cariology, Center for Dentistry, Oral Medicine and Cranio-Maxillofacial Surgery, University of Zürich, Switzerland. wolfgang.buchalla@zzmk.uzh.ch
Lennon
A M
AM
Becker
K
K
Lucke
T
T
Attin
T
T
D000134:Acid Etching, Dental; D020906:Air Abrasion, Dental; D000704:Analysis of Variance; D000818:Animals; D002124:Calcium Fluoride / Q000494:pharmacology*; D002417:Cattle; D003743:Dental Enamel / Q000187:drug effects* / Q000378:metabolism; D003804:Dentin / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D003806:Dentin Permeability / Q000187:drug effects*; D005459:Fluorides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006863:Hydrogen-Ion Concentration; D016369:Smear Layer
D002124:Calcium Fluoride; D005459:Fluorides