Comparative evaluation of chlorhexidine and benzalkonium chloride pretreatments on bond strength durability of immediate dentin sealing with universal adhesive: an in vitro study

Effective and durable bonding of immediate dentin sealing (IDS) is a crucial factor in the success of adhesive-bonded restorations. This study aimed to investigate the influence of chlorhexidine (CHX) and benzalkonium chloride (BAC) pretreatments on the immediate and aged bond strengths of a universal adhesive used in IDS across two etching modes. Flat dentin surfaces were obtained from 120 molars and divided into six groups based on pretreatments (no treatment, CHX, and BAC) in two etching modes (etch-and-rinse (E&R) and self-etch (SE)) using All Bond Universal, in conjunction with a hydrophobic resin layer. Following the provisional stage and resin cementation, immediate and aged shear bond strengths (SBS) were measured after 24 h and 1 year of storage, respectively. The data (in MPa) were analyzed using ANOVA and Tukey tests (p < 0.05). CHX pretreatment did not significantly impact bond strengths, while BAC pretreatment led to a significantly lower immediate SBS in the SE mode (9.91 ± 1.93 MPa) compared to the control group (16.07 ± 3.45 MPa, p < 0.001). In the E&R mode, no statistically significant differences were found among the three pretreatment groups at either storage time (p > 0.05). After one year, SBS values in the SE mode decreased for all groups, with the CHX group showing the lowest value (9.98 ± 3.91 MPa), though these reductions were not statistically significant (p > 0.05). In contrast, SBS values in the E&R mode remained stable or slightly increased, with the BAC group reaching 17.12 ± 4.05 MPa after one year. Aged SBS values in the E&R mode were significantly higher than in the SE mode for the CHX (16.53 ± 2.28 MPa vs. 9.98 ± 3.91 MPa, p < 0.001) and BAC groups (17.12 ± 4.05 MPa vs. 10.55 ± 3.03 MPa, p = 0.001). CHX and BAC pretreatments did not offer additional advantages in terms of long-term bonding performance in IDS with the universal adhesive utilized in this study. When using antibacterial agents, All Bond Universal adhesive in E&R mode could provide better long-term bonding performance than that of its SE mode.