Histopathological studies on the effects of experimental trauma and N-methyl-N-nitrosourea on the developing molar in...

Physical trauma to the developing first molar after initial dentin formation (5-day-old rat) and apposition stage (10-day-old rat) caused disturbance in amelogenesis, dentinogenesis, root formation which lead to aberrant odontogenesis. On the other hand, a combination of trauma and injection of carcinogenic substance (NMU) produced a more pronounced disturbance in odontogenesis and higher incidence of unerupted tooth. The transformation of the retained reduced enamel epithelium to squamous type cells was an interesting finding and has not been reported elsewhere. The presence of large proliferating type of odontogenic cell rests was observed.