Comparison Of Indirect Bonding Methods of Orthodontic Brackets Performed With Conventional And Fully Digital Workflows In Terms Of Microleakage And Shear Bond Strength Parameters: A Randomized Controlled In Vitro Study

Background Accurate bracket placement is an essential step for achieving predictable orthodontic treatment outcomes. Digital workflows using intraoral scanning, virtual bracket positioning, and 3D-printed transfer trays can enhance bonding accuracy and adhesive effectiveness. However, few studies have simultaneously evaluated microleakage, shear bond strength, and adhesive remnant patterns across direct, traditional indirect, and fully digital indirect bonding methods. The present study aims to address this issue by conducting a controlled in-vitro comparison of these three methods. Methods A total of 102 extracted human premolars were randomly allocated to three groups: direct bonding (C), traditional indirect bonding (TIDB), and fully digital indirect bonding (DIDB)(n = 34). Each group was divided into subgroups for microleakage analysis (n = 17) and shear bond strength/Adhesive Remnant Index (ARI) evaluation (n = 17). Microleakage was assessed with 0.5 basic fuchsin dye and quantified by direct measurement of dye penetration beneath bracket bases under stereomicroscopy. Shear bond strength (SBS) was measured using a universal testing machine at a crosshead speed of 1 mm/min. ARI scores were recorded after debonding. Statistical analyses were conducted using IBM SPSS V23 and JAMOVI V2.3.21 software. Results Microleakage analysis showed significant differences among the groups concerning maximum dye penetration values (p < 0.001). The control group showed significantly less microleakage than the TIDB group; however, the differences between the control and DIDB groups were not statistically significant. Additionally, gingival regions exhibited significantly higher microleakage than occlusal regions (p < 0.001). In SBS testing control group showed significantly higher values (p = 0.004)). Specifically, the control group showed significantly higher SBS than the TIDB group, while no significant differences were observed between the C and DIDB groups. ARI score distributions did not show significant variation across the groups (p = 0.110). Finally, no significant correlations were observed among SBS, ARI, or maximum dye penetration values across groups (p > 0.05). Conclusions In this study fully digital indirect bonding method showed better marginal sealing and more consistent adhesive behavior compared to traditional indirect bonding, while maintaining shear bond strength similar to that of direct bonding. Digital workflows appear to reduce laboratory-related variables, improve precision, and provide safer adhesive bonding results.