<prompt> Organisms involved in pit and fissure caries:Streptococcus mutans.Lactobacillus.Actinomyces.All of the above.  <response>: Pit fissure caries in initiated by a wide variety of organisms like S. mutans, Lactobacillus and Actinomyces species as they colonize in these retentive areas. However, only S.mutans very significantly S. salivarius by chance have been proved to colonise smooth surfaces. 