Aim To evaluate and compare the microleakage In class II restorations using open- and closed-sandwich techniques with zirconomer as an intermediate material. Material and method Twenty-six non-carious mandibular first molars were selected and randomly divided into two groups (groups 1 and 2 where n=13). A standardized Class II preparation was made with the cervical margin 1 mm below the cementum-enamel junction. Samples of group 1 were restored using the open-sandwich technique and samples of group 2 with the close-sandwich technique, and zirconomer was used as an intermediate restorative material. Following that, the restorations underwent 200 heat cycles with dwell times of 20 seconds at 5°C and 55°C. Dye penetration and scanning electron microscope (SEM) analysis using the replica approach were used to assess adaptation at the cervical margin. The data were statistically analyzed using the Paired T-test (p<0.05). Results Lower dye penetration was seen in the open-sandwich technique compared to the closed-sandwich technique (p<0.001). Conclusion When comparing the open-sandwich technique with the closed one, it was observed that less microleakage was seen in the open-sandwich technique as it has better marginal adaptation and fewer voids.