Effects of S-PRG Fillers-containing Composite on Demineralization Inhibition of Enamel Surface: Optical Coherence Tomography (OCT) and Micro Computed Tomography (Micro CT) Approaches

Objectives: Acidogenic bacteria formed biofilm results in low pH and shift the calcium phosphate balance which facilitates caries formation. Nutrification of surface pre-reacted glass ionomer (S-PRG) fillers may inhibit the acidification on tooth surface. The purpose of this study was to evaluate the demineralization inhibition effects of S-PRG filler-containing composite on enamel by using OCT and Micro CT.
Methods: An artificial caries model was established by the demineralization (pH = 4.2) and remineralization (pH = 7.0) cyclic tests for fourteen days. Sixteen specimens, 5mm x 5mm x 2.5mm enamel block with a cylinder cavity for each, were divided into two groups (n = 8). S-PRG group: cavities were filled with Beautifil II^® composite resin (Shofu Inc., Kyoto, Japan). Non-S-PRG group: cavities were filled with Estelite^® composite resin (Tokuyama Dental Co., Tokyo, Japan). Dentin bonding agent used in this study was OptiBond^® (Kerr, USA). We qualitatively and quantitatively examine the demineralization lesion of surrounding enamel portion by non-destructive methods−Micro-CT and OCT. The average lesion volume and depth of demineralization in enamel were calculated. Vickers microhardness (VMH) of enamel surrounding test composite was also evaluated.
Results: The obtained data from OCT and Micro-CT were well correlated. S-PRG group presented significantly shallow demineralization lesion depth (30.5 ± 15.5 µm) compared to non-SPRG group (37.8 ± 12.7 μm) (p<0.05). There is no significant difference of average lesion volume between S-PRG (0.062 ± 0.033 mm³) and non-S-PRG groups (0.069 ± 0.027 mm³). For the VMH test, S-PRG group (59.8 ± 11.3) obtained significant higher value (p<0.05) than non-S-PRG group (31.72 ± 4.48).
Conclusions: The obtained data from OCT and Micro-CT were well correlated. S-PRG group presented significantly shallow demineralization lesion depth (30.5 ± 15.5 µm) compared to non-SPRG group (37.8 ± 12.7 μm) (p<0.05). There is no significant difference of average lesion volume between S-PRG (0.062 ± 0.033 mm³) and non-S-PRG groups (0.069 ± 0.027 mm³). For the VMH test, S-PRG group (59.8 ± 11.3) obtained significant higher value (p<0.05) than non-S-PRG group (31.72 ± 4.48).