In vitro evaluation of the compressive strength of glass ionomer cement modified with propolis in different proportions

Abstract

Background: Antibacterial additives are frequently added in an effort to enhance the antibacterial properties of glass ionomer cement (GIC). GIC modified with ethanolic extract of propolis (EEP) has been proven to improve GIC’s antibacterial properties, but this modification is suspected to have detrimental impacts on its compressive strength. Objectives: To evaluate the compressive strength of GIC incorporated with different proportions of propolis extracts from Trigona spp. from Garut, Indonesia. Methods: This experimental in vitro laboratory study comsisted of 20 cylindrical glass ionomer specimens divided into four groups according to the proportions of propolis added to the GIC liquid: Group A: conventional GIC (control), Group B: 25% EEP added (% w/w), Group C: 30% EEP added (% w/w), and Group D: 35% EEP added (% w/w). A universal testing machine was used to assess compressive strength after the samples were immersed in artificial saliva and incubated for 24 h. Data were analyzed with one-way analysis of variance and Tukey’s test (P < 0.05). Results: The addition of EEP decreased the compressive strength of the GIC liner. Mean compressive strength values were 118.06 ± 24.1 MPa (Group A), 103.17 ± 10.26 MPa (Group B), 79.18 ± 9.99 MPa (Group C), and 77.03 ± 6.13 MPa (Group D). In comparison to the control group, a nonsignificant difference was observed when 25% EEP was added (P > 0.05), whereas both 30% EEP and 35% EEP resulted in significant decreases in compressive strength (P < 0.05). Conclusion: GIC modified with 25% EEP might be a promising restorative material for cavity linings.