CHEMICAL AND PHYSICAL STUDIES OF ENAMEL FROM HUMAN TEETH

II. SPECIFIC GRAVITY, NITROGEN CONTENT, AND HARDNESS RATING OF DISCOLORED ENAMEL

¹ Department of Anatomy and Division of Dental Research, University of Rochester, School of Medicine and Dentistry, Rochester, N. Y.

1. Microscopic study of brown spots suggests an alteration in the organic material in these areas. The presence of increased residue on decalcification of brown spots indicates an increase in the organic content of the lesion.

2. The organic content of these areas is higher than that of sound enamel according to the nitrogen analysis.

3. The finding that the brown spots have a decreased hardness and lower density than the sound enamel suggests a loss of inorganic material in these areas.

4. The nature of these changes is not fully understood, but it seems likely that the increased organic content is of extraneous origin.