Abstract Objective To compare the sealing ability and marginal adaptation of three calcium silicate-based cement (Biodentine, Pro root MTA, MTA Angelus) using a bacterial leakage model and scanning electron microscope (SEM). Methods Recently extracted lower first premolars were randomly categorized into three experimental groups (n = 15 samples), positive control (n = 5 samples), and negative control group (n = 5 sample). Samples from the experimental groups and positive control group were subject to cavity Class I occlusal preparation followed by modified coronal pulpotomy. Different types of bioceramic dressing material were placed in 3 mm thickness accordingly, group 1 (Biodentine), group 2 (MTA Angelus), and group 3 (ProRoot MTA). No dressing material was placed in the positive control group (group 4). All samples were placed in the incubator for 24 h at 37℃, 100% humidity, for the materials to be completely set. The final restoration was placed using the Z350 resin composite. A double layer of nail varnish was applied over all the sample surfaces except the occlusal site. Whereas the samples’ surfaces in the negative control, were completely covered. A 3 mm length was measured from the root apex of the samples from each group, before proceeding with the resection. The bacterial leakage test was performed using Enterococcus faecalis TCC 23,125, and a sample from each experimental group was randomly chosen for SEM. Data analysis was conducted under the One-way ANOVA test, completed by Tukey’s post hoc test. Results There is a significant difference in sealing ability and marginal adaptation between the groups. (p < 0.05). The study showed that Pro Root MTA had the superior sealing ability and marginal adaptation compared to Biodentine and MTA Angelus. Conclusion The ProRoot MTA as a coronal pulpotomy pulp dressing material, was found to have a better marginal adaptation and sealing ability compared to three other bioceramics materials. The material would be the better choice during clinical settings and procedures.