ANKYLOSIS OF THE MOUSE MOLAR AFTER SYSTEMIC ADMINISTRATION OF 1-HYDROXYETHYLIDENE-1,1-BISPHOSPHONATE (HEBP)

The proposed homeostasis between fibroblasts in the periodontal ligame nt and bone cells lining the inner aspect of the alveolar wall is thou ght to be responsible for maintaining the width of the periodontal lig ament space. In the present study, we attempted to interfere with this cellular balance by systemic administration of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP). The maxillary left molars of mice were extrac ted. They then received a daily subcutaneous injection of HEBP (10 mg P/kg b.w.) for periods of 10, 30 or 50 days. A 2nd group of animals re ceived HEBP without molar extraction. Control groups were injected wit h Ringer's solution. The animals were sacrificed after the last inject ion and the mandibles processed for light and electron microscopy. HEB P treatment caused a significant decrease of the width of the periodon tal ligament space which was influenced by time. Ankylosis started to occur after 30 days, predominantly in the interradicular areas and was more common around unopposed teeth. At 50 days, signs of resorption w ere seen along the acellular cementum layer. During HEBP-administratio n, extensive deposition of newly formed cementum matrix was observed a long the cellular cementum but this activity was not seen along the ac ellular cementum. It is concluded that HEBP interferes with the mechan isms that mediate preservation of the periodontal ligament width.