Preventive
Conrad Chou, DDS
Resident
University of California San Francisco
University of California San Francisco
San Francisco, California, United States
Misun Kang, PhD
UCSF School of Dentistry
Rosalyn Sulyanto, DMD, MS
Postdoctoral Research Director
Boston Children's Hospital
Boston, Massachusetts, United States
Dilworth Y. Parkinson, PhD
Lawrence Berkeley National Laboratory
Sunita P. Ho, MS, PhD
UCSF School of Dentistry
Thomas Tanbonliong, DDS
Program Director
University of California, San Francsico
SAN FRANCISCO, California, United States
Purpose: To investigate the effect of silver diamine fluoride(SDF) on physiochemical properties by correlating permeability with mineral density(MD) and elemental composition of hypomineralized enamel and carious dentin.
Methods: Enamel and dentin from extracted carious primary teeth with(N=3;41 regions) and without(N=7;43 regions) SDF treatment in-vivo, and hypomineralized enamel from permanent molars with(N=4;32 regions) and without(N=7;50 regions) SDF treatment in-vitro were scanned using X-ray micro computed tomography. Spatial elemental maps of Zn2+ and Ca2+ were generated using X-ray fluorescence microprobe. Physicochemical properties were computed using Porous Microstructure Analysis, BoneJ, and RStudio software. Physicochemical effectors of tissue permeabilities were delineated using principal component analysis/regression.
Results: Three dentin zones (carious-turbid; carious-transparent; sound dentin) of varying MD, diameter, and tubule occlusions were observed. Permeability of SDF-treated turbid dentin, but not transparent dentin, was significantly lower than those untreated(Turbid-SDF=21(+/-9.8); Turbid-NoSDF=50(+/-26)%; P < .0001). Permeability of severely hypomineralized enamel was comparable to sound dentin and was significantly higher than mildly hypomineralized enamel(Severe=11(+/-7.9); Mild=4(+/-4.2)%; P < .0001), though both were unaffected by SDF-treatment in-vitro. Principal component regression identified Zn2+ level(P < .0001) and tissue anisotropy(P < .0001) as significant effectors of tissue permeabilities. Principal component analysis and pairwise permutational multivariate analysis indicated that carious dentin with and without SDF and hypomineralized enamel are physiochemically distinct(P < .0001).
Conclusions: Silver diamine fluoride treatment alters physicochemical properties of carious dentin but not hypomineralized enamel, and only reduces the permeability of turbid dentin. Zn-mediated mineral densities and resulting permeabilities of enamel and dentin are postulated to be biologically controlled, underscoring tissue adaptation and pulp function.