INTRODUCTION: The aim of adding chlorhexidine (CHX) to glass ionomer cements (GIC) is to improve their antibacterial property, but it may interfere with their bond to dentin. OBJECTIVE: To evaluate the influence of adding chlorhexidine diacetate at different concentrations to a high-viscosity GIC on its bond to sound and artificial caries-affected dentin. MATERIAL AND METHOD: Eighty human third molars were used, on which an area of dentin was exposed on the occlusal surface. Half of the specimens were kept sound and the other half were subjected to artificially induced caries. CHX was mixed with GIC powder at 0.5%, 1% and 2% (w/w). GIC without CHX was used as control. On each dentin surface a specimen measuring 1 mm in diameter and 1 mm high was made. The samples were kept at 37 °C and 100% humidity for 24 hours and subject to microshear testing. The results were analyzed using Kruskal-Wallis and Mann Whitney tests (α=0.05). RESULT: There was no significant difference between bond strength of sound and caries-affected dentin (p>0.05). For both substrate conditions, groups GIC, GIC+0.5% CHX and GIC+1% CHX showed statistically similar bond strength (p>0.05), and higher than that of GIC+2% CHX (p<0.025). Cohesive and mixed failures were predominant in all groups. CONCLUSION: The addition of 0.5% and 1% chlorhexidine did not result in negative changes in the bond strength of GIC to caries-affected and sound dentin.

Os cimentos de ionômero de vidro têm se destacado como um material de grande interesse na clínica odontológica. Suas formulações permitem serem usados tanto para forramento de cavidade como restauração e cimentação de peças protéticas. É um material que apresenta propriedades excelentes como adesão à estrutura dentária, coeficiente de expansão térmica, liberação de fluoreto e compatibilidade biológica. Sua compatibilidade biológica é estudada e analisada através de diversos testes laboratoriais, que permitem verificar as novas formulações de materiais, pois estão em constante desenvolvimento. Este artigo analisa e discute a compatibilidade biológica dos cimentos de ionômero de vidro, bem como os testes para se analisar a biocompatibilidade, além de relatar a importância dessa propriedade no material ionomérico.

Introduction Glass ionomer cements are often used as a base or cavity lining prior to restorative material. Objective To evaluate the bond strength of a composite resin to different glass ionomer cements, when using a two-step conventional and self-etching adhesive systems. Material and method Three glass ionomer cements (Ketac Molar Easymix, Vitremer and Vitrebond), the composite resin Filtek Z350 XT and the adhesive systems Adper Single Bond 2, Clearfil SE Bond and Adper Easy One were used. As negative control, resin was bonded to cement without using an adhesive system. Holes (4 mm diameter, 2 mm deep) prepared in acrilic bloks were filled with the glass ionomer cements (n=12/group). On the surface, an area of 1mm in diameter was delimited, the adhesive system was applied, and a specimen of composite resin with 1 mm height was made. After 24 hours storage (37 °C and 100% humidity), the microshear test was performed. Data were analyzed using two-way ANOVA and Tukey test for comparison between groups (α=0.05). Result The adhesive systems significantly improved the bond strenght of composite resin to glass ionomer cements (p≤0.001). There was no significant difference in bond strength when self-etching adhesive systems were compared with the simplified etch-and-rinse adhesive, except for Vitrebond where Clearfil SE Bond determined higher bond strength when compared to Adper Single Bond 2 (p=0.003). Conclusion Self-etching adhesive systems are a good option for establishing the bond between the composite resin and the glass ionomer cement.

Aim: To evaluate the bond strength of a GIC associated with chlorhexidine (CHX) to sound and caries-affected dentin, immediately and after six months of storage. Methods: Sixty molars were assigned to two groups of 30 teeth. One had flat dentin surfaces produced and submitted to caries induction to obtain a caries-affected dentin.  In the other group dentin was maintained sound. Teeth of each group were randomly reassigned to three subgroups (n=10) according to the concentration of CHX added to the GIC (0%, 1% and 2% by weight).  Two specimens (1mm diameter x 1 mm high) of the same material were constructed on each dentin surface. One was submitted to the microshear bond strength (µSBS) test after 24 hours and the other after 6 months of storage in water at 37oC. Failure modes were analyzed under a stereomicroscope. Bond strength data were analyzed by three-way ANOVA followed by Games-Howell tests for multiple comparisons, and failure modes by the Chi-square test (α = 0.05). Results: The µSBS values obtained to sound dentin were higher compared with those to caries-affected dentin (p≤0.001). In sound dentin, the group with 2% CHX showed lower  µSBS values compared with 0% and 1% CHX after 24 hours (p=0.005 and p=0.032 respectively). In caries-affected dentin, after 24 hours, µSBS in group with 1% CHX was statistically higher than the values in groups with 2% CHX after 24 hours (p=0.001) and 1% CHX after 6 months (p=0.024). Irrespective of the condition of substrate, comparisons showed no statistically significant differences between the other groups (p≥0.053). Cohesive in material and mixed failures prevailed for all groups. Conclusions: The addition of CHX at concentrations of up to 2% to the GIC did not affect the bond strength of the material to sound and caries-affected dentin in a long-term evaluation.