ABSTRACT: 0997

Ion Release of Resin-Modified Bioactive Glass-Ionomer Cement for Restorative Dentistry

F. PELOGIA¹, H.B. DAVIS², J.C. MITCHELL², A. DELLA-BONA³, and J.L. FERRACANE², ¹Sao Paulo State University, São José dos Campos, Brazil, ²Oregon Health & Science University, Portland, USA, ³University of Passo Fundo, Passo Fundo, RS, Brazil

Bioactive restorative materials may stimulate the repair of tooth structure though the release of remineralization-aiding components including calcium and phosphate.

Objective: To measure ion release from resin-modified bioactive glass ionomer cement (RMBGIC) containing various formulations of bioactive glass (BAG).

Methods: BAG was prepared by sol-gel methods, ground, micronized, and mixed with GIC powder (Fuji II LC, GC) in proportions and compositions shown below. The mixed-ionomer powders were combined with standard RMGIC liquid (Fuji II LC, GC) and light cured (40s; Ultra Lume LED, 1100mW/cm²) in cylindrical disk molds (5mmx2mm). Resulting cured RMBGIC was ground and sieved to 100µm and immersed (20mg;n=3) in 3 ml of simulated body fluid(SBF), at 37°C for 1/4, 1/2, 1, 3, and 24 hours with continuous agitation. Following centrifugation and decanting, [Ca⁺²] and [H_xPO₄^3-x] in the SBF were measured by ion specific electrode and visible spectroscopy, respectively. Ion release for the groups were compared using ANOVA/Tukey(α= 0.05).

Glass

Composition

Powder:Liquid ratio

GI:BAG ratio

Fuji II LC (control)

Standard

1:2

1:0

BAG 65

65%SiO₂-31%CaO-4%P₂O₅

1:5

1:1

BAG 75

75%SiO₂-21%CaO-4%P₂O₅

1:4

1:1

BAG 85

85%SiO₂-11%CaO-4%P₂O₅

1:3

1:1

Results: The [H_xPO₄^3-x] in SBF immediately increased for all RMBGICs. The release slowly decreased after 1 hour, yet remained higher than the original SBF over the 24h period. The [H_xPO₄^3-x] in SBF for the control GIC continuously decreased. Overall, BAG 85> BAG 75= BAG 65 > GIC for [H_xPO₄^3-x]. The [Ca] showed marked initial increase with all RMBGICs and the release remained above levels produced by the control GIC.

Conclusion: Resin modified glass ionomer cement containing bioactive glass releases more Ca and P into SBF than the GIC alone. The use of bioactive cements in dentistry may help to enhance dentin remineralization by providing a reservoir of ions for use in hydroxylapatite formation.

Acknowledgement: Partially supported by CAPES-Brazi.

Seq #108 - Resin Cement Mechanical Properties, Glass Iomoners
3:30 PM-4:45 PM, Thursday, July 3, 2008
Metro Toronto Convention Centre Exhibit Hall D-E

Back to the Dental Materials 3: Ceramic-based Materials and Cements Program