RADIOPACITY OF ORAL STRUCTURES AS A BASIS FOR SELECTING OPTIMUM KILOVOLTAGE FOR INTRAORAL ROENTGENOGRAMS

¹ Departments of Radiology and Oral Physiology, Tufts College Dental School, Boston, Mass.

The density of oral structures in terms of mm. of ivory as seen on the average intraoral film varies beyond the limits of 19.5 and 4.5 mm. of ivory. These may properly be considered the minimal range.

If the quantity of radiation can be critically controlled it is possible to demonstrate, at kilovoltages commonly used on dental x-ray machines (approximately 65 kvp), the full scale of ivory thicknesses varying from 4.5 to 19.5 mm. Slight variations in quantity (mas) result in either overexposure of the least dense areas or underexposure of the most dense areas. If the density range exceeds the limits of 4.5 and 19.5 mm. the probability of full coverage is further reduced.

As the kilovoltage is increased with proper decreases in mas the full scale of structural density can be seen in spite of considerable variation in the quantity of radiation. This greater latitude will accommodate densities in oral structures beyond the range of 4.5 and 19.5 mm. of ivory.

On the basis of this study and clinical evidence in its support, the optimum kilovoltage for intraoral radiography appears to be 90 to 95 kvp.