The roughness, microhardness, and surface analysis of nanocomposites after application of topical fluoride gels.
OBJECTIVE
Application of acidulated phosphate fluoride (APF) gels has long been considered to cause deterioration of composite surfaces. The aims of this study were to demonstrate that nanocomposite surfaces were not affected by some APF gels and to investigate the possible underlying mechanisms.


METHODS
The elemental composition and viscosity of 3 acidulated phosphate fluoride (APF) agents (60 Second Taste Gel, Topex, and Zap) and 1 neutral fluoride agent (pH7 Gel) were analyzed. Subsequently, 320 specimens of 3 nanocomposites (Premisa, Filtek Z350, and Grandio) and a microhybrid composite (Estelite Sigma) with 80 specimens for each composite were randomly divided into 5 groups (n=16) and treated with 4 fluoride gels as well as distilled water which served as the control. Fluoride gels were applied on composite resin surfaces 4 times, 30 min each time. The roughness and microhardness were measured after treatments. Qualitative examination of the surface degradation of the composites was carried out with Fourier transforming infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).


RESULTS
Topex and Zap did not cause surface changes of composite resins, the possible reason being ascribed to the presence of magnesium aluminum silicate (MAS) clays. In contrast, 60 Second Taste Gel treatments caused significant roughness increase, microhardness decrease, more prominent filler dissolution, and IR spectral changes of Premisa, Filtek Z350, and Grandio. Estelite Sigma was less affected by the 4 fluoride gels.


CONCLUSIONS
The composite surfaces were not affected by Topex or Zap even after extended treatments. These two APF gels may be more suitable for clinical applications.
Department of Dentistry, Mackey Memorial Hospital, Taipei, Taiwan.
Shu-Tuan
ST
Yeh
Hao-Ting
HT
Wang
Hua-Yang
HY
Liao
Shun-Lian
SL
Su
Che-Chen
CC
Chang
Hung-Chan
HC
Kao
Bor-Shiunn
BS
Lee
D000149:Acidulated Phosphate Fluoride / Q000032:analysis / Q000737:chemistry*; D017607:Aluminum Compounds; D000538:Aluminum Silicates / Q000737:chemistry; D017609:Barium Compounds / Q000737:chemistry; D002327:Cariostatic Agents / Q000032:analysis / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D005460:Fluorides, Topical / Q000032:analysis / Q000737:chemistry*; D005782:Gels; D006244:Hardness; D006801:Humans; D008274:Magnesium / Q000737:chemistry; D017616:Magnesium Compounds; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013997:Time Factors; D014783:Viscosity; D014867:Water / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
D017607:Aluminum Compounds; D000538:Aluminum Silicates; D017609:Barium Compounds; D002327:Cariostatic Agents; D003188:Composite Resins; D003764:Dental Materials; C507124:Estelite sigma; D005460:Fluorides, Topical; D005782:Gels; C509998:Grandio; D017616:Magnesium Compounds; D017640:Silicates; C415406:barium borosilicate; C102738:barium glass filler; C533204:filtek Z350; C507210:premise composite resin; D014867:Water; D000149:Acidulated Phosphate Fluoride; C033065:aluminum magnesium silicate; D012822:Silicon Dioxide; D015040:Zirconium; D008274:Magnesium; C028541:zirconium oxide