The occlusal surface of a tooth is affected by the development of biofilm in pits and fissures as bacteria and food particles accumulate in its complex structure. In this study, miswak fibers containing cellulose and antimicrobial extract were incorporated in commercial pit and fissure sealants. The miswak powder was characterized by different analytical techniques. The powder was mixed in different ratios (0–5%) into a pit and fissure sealant to result in five sealants (Groups 0–5), and their mechanical properties i.e. flexural strength, compressive strength, and Vickers hardness were evaluated. The sealants were also evaluated against
streptococcus mutans
oral pathogenic bacteria. SEM analysis confirmed irregular shape and micron-size particles of miswak powder. The infrared spectral analysis and X-ray differential peaks showed characteristic peaks related to miswak fibers. The particle appearance increased in prepared pits and fissure sealants with higher loading of miswak powder in SEM analysis. The flexural strength, compressive strength, and Vickers hardness values were obtained in the range of 148–221 (±16.6:
p
-value < 0.001) MPa, 43.1–50.3 MPa (±1.7:
p-
value <0.001), and 15.2–21.26 VHN (±0.56:
p
-value <0.001) for control and prepared sealant specimens respectively. In the antibacterial study, the zone of inhibitions increased with increased content of miswak from 15.6 ± 0.45 mm (Group 1) to 20.3 ± 0.32 mm (Group 5). The MIC was calculated to be 0.039%. The prepared experimental sealant had acceptable mechanical and good antibacterial properties therefore it could be recommended as an efficient pit and fissure sealant.