Aims: to assess the different histologic reactions in dentin-pulp organs in the pulp of mongrel dogs after stimulation with Low-Level Laser (LLL), mineral trioxide aggregate (MTA), and TheraCal light-cured (LC) as capping therapies and compare it with the conventional calcium hydroxide (Ca(OH)) cement material. Subjects and Methods: Eight male mongrel dogs weighing 10-15 kg and 12-18 months old were chosen for this study. The pulp exposure was done via the preparation of a class V cavity on the buccal surface of the premolar teeth. In each doge, the premolar teeth were involved and assigned to four different groups based on the treatment procedure (group 1: LLL; group 2: MTA; group 3: TheraCal LC; and group 4; Ca(OH). The histological reactions at the site of exposure and the mid-region (including odontogenic zones, pulp cores, and supposed tertiary dentin formation) were recorded at 3 different follow-up periods (7, 14, and 42 days). Results: The histological finding showed different histological reactions in the dentin-pulp organs at the site of exposure and the mid-region in response to the different capping materials at different follow-up periods with a higher positive effect with Laser, and MTA followed by TheraCal LC, and Ca(OH) at different follow-up periods.Conclusion: The use of Laser, and MTA as pulp-capping therapies has a considerable positive histological reaction on the dentin-Pulp organs when compared with TheraCal and Ca(OH).