Enamel hypoplasia mostly affected maxillary incisors.

Epidemiologic studies suggest that intake of excess all-trans-retinoic acid (RA) during embryogenesis induces various developmental defects and the central nervous system (CNS) represents a major site of the teratogenic action of RA.

After analyzing glaze shrinkage freckle on cap and pin insulator body observed in manufacturing process,the author attributes it firstly to deviation of body moisture from technological specification,and secondly to low temperature at glazing and thick ink for marking.