2820 Effects of smear layer on enamel demineralization adjacent to RMGI. (Part-II)
A. AL-HELAL, S. ARMSTRONG, M. HOGAN, J. HARLESS, and J. WEFEL, College of Dentistry, University of Iowa, Iowa City, USA

Objectives: To evaluate the influence of different smear layer treatments on enamel artificial caries-like lesion development, mineral loss and fluoride uptake adjacent to resin-modified glass ionomer (RMGI). Methods: Several cavity surface treatment modalities were investigated including; maintenance, partial removal (Polyacrylic acid, PAA), complete removal (Phosphoric acid, H3PO4) of smear layer, with or without adhesive liner application (Scotchbond Multi-purpose, SMP). 90 sound human molars were prepared with a standard class V cavity at the CEJ and assigned to six groups prior to the placement of RMGI (Photac-fil); G1: no treatment, G2: 25%PAA, G3: 37%H3PO4, G4: SMP adhesive, G5: 25%PAA+SMP primer and adhesive, G6: 37%H3PO4+SMP primer and adhesive. Specimens were then aged for 2 weeks, thermocycled, and subjected to an artificial caries challenge (pH 4.4) for 5 days. Specimens were sectioned longitudinally and examined with polarized light microscopy, microradiography and electron microprobe to obtain enamel lesion depth (LD), lesion area (LA), mineral loss (D Z, vol%× m m) and fluoride-uptake profile. Results:

Group

1

2

3

4

5

6

LD(m m)

142.3(51.1)

100(25.6)

77.5(38.4)

173.2(26.3)

145.6(42.6)

164.4(37.7)

LA(m m2)

14927(5001)

10411(2704)

8006(4193)

18711(2993)

15906(3588)

17304(2952)

D Z

8097(5024)

5069(2296)

2577(1668)

11830(3378)

9538(2609)

11433(3317)

ANOVA and Tukey tests (p< 0.0001) revealed that, H3PO4 alone treated group (G3) had significantly the least amount of demineralization compared to other groups except PAA alone treated group (G2). Furthermore, PAA alone treated group (G2) was significantly less than SMP lined groups (G4,G5,G6) for both LA and D Z and less than the untreated group (G1) for LA only. Its LD was also significantly less than SMP adhesive treated group (G4) and H3PO4+SMP treated group (G6). Conclusions: Complete or partial removal of the smear layer prior to the placement of RMGI may improve secondary caries inhibition at the enamel margin.

Seq #259 - Demineralization, Remineralization
3:45 PM-5:00 PM, Friday, 8 March 2002 San Diego Convention Center Exhibit Hall C

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