Effect of 2%Chlorhexidine Digluconate on Adhesion to Different Cola-Eroded Dentin

Objectives: As chlorhexidine digluconate (CHX) can inhibit matrix metalloproteinases activated under erosive challenges, its application before restoration has been advocated. This study aimed to evaluate the association of 2%CHX on adhesion to eroded dentin provoked by different cola soft-drinks. The null hypotheses were: 1- There is no difference in bond strength to normal dentin or eroded by regular-cola (RC) or light-cola (LC); 2- There is no difference in bond strength to dentin associated or not with 2%CHX. Methods: Sixty extracted caries-free human third molars were sectioned in the mid-coronal third to expose flat dentin, subsequently polished with 600-grit SiC paper. Specimens were divided into three groups: CONT- stored in artificial saliva (control group), RC and LC, eroded respectively by RC or LC in 5minute immersion for 3x/day during 5 days. All these groups were stored overnight in artificial saliva until complete 24 hours. Following, the surfaces were etched with 37% phosphoric acid for 15s, washed and blot dried. Half specimens of each group were rehydrated with 1.5μL of distillated water and half with 1.5μL of 2%CHX. The surfaces were bonded with Single Bond 2 and composite buildups were constructed incrementally with Filtek Z350. After storage in water for 24h at 37˚C, the specimens were prepared for microTBS testing with a cross-sectional area of approximately 1mm2. They were then tested in universal testing machine (EMIC) at 0.5 mm/minute. Data were analyzed by two-way ANOVA and Bonferroni tests (α= 0.05). Results: Bond strength means and standard deviations (MPa) without and with 2%CHX were respectively: CONT- 37.28(9.57)/40.32(5.53), RC- 20.01 (4.91)/17.61(5.54), LC- 21.95(7.53)/ 21.30(3.65). RC and LC significantly reduced bond strength to dentin while 2%CHX was not a significant factor to any investigated condition. Conclusion: 24h-immediate bond strength was negatively affected by both soft drinks, while 2%CHX did not improve it.