The Effect of Single Doses of Irradiation Upon the Eruption of the Upper Rat Incisor

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Abstract
The effects of a single exposure to X-ray on the eruption of the upper incisor was studied in 80 white rats weighing 180-200 g. Animals were irradiated with 500 r, 1000 r, 2000 r, 2500 r, 3000 r, and 4000 r. 8 animals were used as controls. The animals were observed up to 20 weeks. Only the area of the upper incisors was exposed to irradiation. The physical factors used were 100 Kv, 5 MA, STD of 12.5 cm., no filter, HVL of 1 mm. Al, and a field of 2.5 cm. The output was 320 r/ min. The rate of eruption was detd. by notching the upper incisor at the gingival margin. The normal controls showed a weekly eruption rate of the upper incisor between 2 and 2.6 mm./week. The animals receiving 500 and 1000 r showed a similar curve. The animals receiving 2000 r showed a dip in the eruption rate for the first 6-7 weeks and from then on a normal curve. Irradiation with 3000 r and 4000 r produced cessation of eruption within 3 weeks.
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