Enhancement of orthodontic anchorage and retention by the local injection of strontium: an experimental study in rats

To examine the clinical and histological effects of locally injected strontium on the anchoring unit of a rat model of an experimental relapsed tooth movement. Thirty-six 10-week-old male Wister rats were randomly divided into two groups of 18 animals that were then randomly divided into three subgroups of six animals corresponding to three observation periods: T1 = 1 week, T2 = 2 weeks, and T3 = 3 weeks. In the first experiment, both the right and left maxillary first molars were moved buccally with a standardized expansive spring. Strontium chloride solution was injected every 2 days into the subperiosteal area buccal to the left maxillary first molar [the experimental side]. The right-sided first molar was injected with distilled water as a control. In the second experiment, maxillary first molars were moved buccally with the spring. After 3 weeks, the spring was removed. Two days before the spring removal, strontium chloride was injected into the palatal side of left-sided maxillary first molar and distilled water was injected into the palatal side of the right-sided maxillary first molar as in experiment 1. At the end of the experimental period, significant levels of inhibition were noted in terms of both tooth movement and relapse movement in strontium-injected sides. Histological examinations showed that strontium enhanced the number of osteoblasts and reduced the number of osteoclasts. The local injection of strontium can inhibit the degree of experimental and relapsed tooth movement in a rat model

Histopathological and immunohistochemical study of giant cell granuloma of the jaw and giant cell tumor of long bones [comparative study]

Central giant cell granuloma [CGCG] and peripheral giant cell granuloma [PGCG] are tumor like lesions that affect jaw bones, while giant cell tumor [osteoclastoma] is a tumor that affects the long bones [e.g. tubular bones]. Its affection of the jaw bones is a matter of debate. Both are very similar in their histopathological features while they vary in their clinical behavior. GCT shows a more aggressive behavior than GCG. To evaluate the expression of [Proliferating cell nuclear antigen] and [P53] in peripheral and central giant cell lesion of the jaw and giant cell tumor of long bones with correlation to histopathological parameters. A total of 17 [GCT], 15 [CGCG] and 16 [PGCG] cases where enrolled in this study. Immunohistochemical staining with PCNA and P53 monoclonal antibody was performed. A non-significant difference m proliferative activities was recorded among different histological giant cell lesion subtypes. Giant cell granuloma expressed the same proliferative potential to that of giant cell tumor, moreover PCNA expression was not statistically correlated to different histopathological paramters of lesion subtype. On the other hand. The anti-apoptotic potential of giant cell granuloma which expressed by anti P53 monoclonal antibody was the same of that of giant cell tumor. Results of this study proved that the biological behavior namely P53 and PCNA activities was comparable between giant cell lesions and giant cell tumor. This suggest that these two conditions may act as one disease entity with a spectrum of clinical behavior, possibly due to certain differences in anatomical location which by itself affect its biological behavior. This hypothesis needs further verification concerning the clonality of the lesion to be accepted or refused