Aim: The main aim of the present study is in vitro assessment of the diffusion ability and degradation of calcium hydroxide from pastes prepared by using different vehicles to determine the influence of a vehicle on pH of calcium hydroxide [Ca(OH) 2 ] pastes. Materials and methods: A total of 44 single-rooted premolar teeth were used in this study. The tooth crowns were removed and the root canals were prepared. Depending on the vehicle to be used for preparing calcium hydroxide pastes, four groups were made: group I: Ca(OH) 2 saline paste (control group), group II: Ca(OH) 2 neem , group III: Ca(OH) 2 aloe vera , group IV: Ca(OH) 2 turmeric paste. After biomechanical preparation, calcium hydroxide herbal paste dressings were applied and sealed with resin-based cement. The teeth were placed in containers with distilled water, and the pH of the water was measured at regular intervals over 3, 24, and 168 hours. Results: The present study showed all herbal pastes allowed the diffusion of ions, but pastes prepared with aloe vera showed more ion diffusion and a marked increase in pH, depicting better support for calcium hydroxide action. Conclusion: Aloe vera allows better diffusion of calcium hydroxide through dentinal tubules, thus enhancing its action, and advises its use as a vehicle for placing intracanal medicament. Clinical significance: Calcium hydroxide [Ca(OH) 2 ] is the most common and effective intracanal medicament. However, CH is not so effective when used alone. Therefore combinations are required to enhance its clinical properties. To be effective, diffusion of hydroxyl ions are required for which vehicle plays a significant role.