ORAL EFFECTS OF INJECTED STRONTIUM 90
Studies were carried out on the jaws of rabbits injected with Sr/sup 90/ Cl/sub 2/ in single doses, varying between 100 and 1000 mu c/kg, in weanlings and animals. The rabbits were ktlled an hour to 9 months after injection; histological studies were done on one mandible and dosimetric studies were performed on the opposite mandible. The most severe changes in teeth and surrounding tissues were produced weanling rabbits receiving high injected doses (>600 mu c/kg). In this group, pyknotic cells were seen among differentiating odontoblasts after 24 hr (accumulated dose 150 rad) and pulp cells became separated from the internal enamel epithelium by an exadate. After 14 days (2500 rad) depletion of pulp cells in this area was evident. At 30 days growth of the cheek-teeth had almost stopped (4500 rad) and there was fibrosis of the pulps. The recently formed parts of the teeth were of diminished diameter. The younger odontoblasts showed great disorder and the mature parts of the pulps becarne completely replaced by dentine. Production of enamel and growth of the enamel organ were arrested, but the enamel organs did not completely disappear. No neoplastic change was seen in any of the dental tissues with the possible exception of cementum. In rabbits injected as adults with high doses, effects occurred which were in general similar to those seen in the weanlings, but took place after a longer time or were less severe and lasting. In those inlected at under 2 yr, growth and eruption of teeth were generally arrested or much retarded, as in animals injected as weanlings; but in rabbits injected at over 3 yr, continued growth and eruption of teeth were not so much retarded; so that in these, by 6 months after injection, most or all of the dentine which had contained the heaviest burden of Sr/sup 90/ had been lost by attrition. The quality of the tooth pulps and dentine in these older rabbits also showed a high degree of recovery from damage. Pleomorphic proliferation of osteoblastic tissue was seen much later in rabbits injected as adults than in those injected as weanlings-----at 6 months instead of at 2 or 3 months after injection. Dosimetry results showed that this was not due to decreased dose rates in the area concerned, for these and the calculated accumulated doses were much increased. Thus, in the weanling group, the max accumulated dose between the bases of the cheek teeth at the time that osteoblastic proliferation was evident was of the order of 9000 rad but in the adult group 47,000 rad or more. Whereas osteosarcomas were evident in four out of four rabbits of the weanlings series at 6 months after injection, they could not be recognized in the adult group at 6 months and only in one rabbit 9 months after injection. In this animal injected at 21 months of age the max accumulated dose between the bases of the mandibular cheek-teeth was approximates 123,000 rads, compared with the 20,000 to 50,000 rads associated with osteosarcoma of the mandible in the weanlings. The results show that, although there are in the rabbit injected as an adult preferential locations of Sr/sup 90/ in the jaws and especially the teeth compared with the distribution in weanlings, and much higher dose rates in the jaws in all areas initially and in many areas throughout, the development of sarcoma in the jaws is slower. It is not known whether this is due to different reactivity of older tissues, higher dose rate, or other factors. (BBB)
- Research Organization:
- Guy's Hospital, London
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-037080
- OSTI ID:
- 4631166
- Journal Information:
- J. Dental Res., Vol. Vol: 42: Suppl.; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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