Effect of estrogen deficiency on skeletal and alveolar bone density in sheep.

BACKGROUND: This study provides a longitudinal assessment of changes in alveolar and skeletal bone mineral density (BMD) in ovariectomized animals. METHODS: Following ovariectomy (OVX) (n = 6) or sham-operation (n = 6) intraoral radiographs were made at 4-month intervals and serum 17-beta-estradiol, osteocalcin, and interleukin (IL)-6, urinary deoxypyridinium, and salivary IL-6, deoxypyridinium, and osteocalcin concentrations were evaluated. Twelve months after surgery, animals were sacrificed and the mandible and radius/ulna removed. Bones were sectioned and radiographed. Mean BMD and cortical thicknesses were calculated from each region. RESULTS: OVX animals had a progressive decrease in serum 17-beta-estradiol, increased serum osteocalcin and IL-6, urinary deoxypyridinium and salivary IL-6, osteocalcin and deoxypyridinium (P < 0.001), suggesting that they were becoming osteoporotic. The BMD of the radius/ulna and mandibular alveolar bone was significantly reduced in OVX animals (P < 0.05 and P < 0.001, respectively). Reduced alveolar bone BMD became evident in OVX animals 6 months after surgery and became more severe during the subsequent 6 months. Alveolar crestal height was also significantly reduced in OVX animals (P < 0.001). These biochemical and density changes preceded a significant reduction in serum 17-beta-estradiol, which occurred between 4 and 8 months following surgery. CONCLUSIONS: Serial measurements of alveolar BMD predicts loss of skeletal BMD in OVX sheep. Changes in alveolar BMD precede estrogen deficiency, suggesting that early signs of reduced BMD may be detected in peri-menopausal women. The presence of biomarkers of bone metabolism within saliva and their correlation with reduced BMD suggests that saliva could be used as an adjunct screening method for assessment of skeletal bone density.

Preliminary evaluation of a new dental implant design in canine models.

Problems with crestal bone resorption and bone adaptation to dental implants in compromised and weak bone present clinical challenges due to insufficient bone volume. Mathematical models have shown that a new, square-thread, dental implant design increases functional surface area and reduces shear loading at the implant interface. The aim of this investigation was to evaluate the ability of bone to grow between the threads of the new implant and its general biocompatibility in a canine model. Test implants were placed in the mandibles of four beagle dogs after posterior partial edentulism. Three months after implantation, the animals received independent fixed partial dentures, were followed for an additional 6 months, and then euthanized for histological analyses. Analyses revealed that bone grew between the threads and closely apposed the new implant design. Histological observations also revealed that the inferior aspect of the test implant threads were apposed by more bone than the coronal aspect, suggesting a biological advantage for the compressive load transfer mechanism of the new implant design. The results of this study revealed that the new implant design became osseointegrated with bone growing between the threads of the device.

Radiographic bone loss correlations and technetium-99m-MDP bone uptake in ligature-induced periodontal disease in the beagle.

The goal of this study was to develop an animal model for the study of acute periodontal disease using silk ligatures in combination with a soft diet in eleven purebred beagle dogs. The silk ligatures were placed subgingivally on the mandible second and fourth premolar on one side of the mouth; the opposite side served as a control. Dogs were monitored during the 16-20 weeks of ligature placement, and for 48 weeks after ligature removal. Development of periodontal disease was evaluated by radiopharmaceutical uptake into bone, radiographic evidence of alveolar bone loss, attachment loss, gingival index and prostaglandin level. Bone loss occurred on the ligatured side during the ligature phase of the study. Radiopharmaceutical uptake was correlated with radiographic evidence of bone loss during the ligature phase. No significant bone loss occurred during the post-ligature phase. Progressive periodontal disease was induced during ligature placement. However, a chronic less aggressive form was not sustained by soft diet alone after ligature removal.

Segmental spinal fixation of a thoracic vertebral fracture in an adult chimpanzee.

Accidental trauma associated with an epileptic convulsion in a 10-year-old, male chimpanzee (Pan troglodytes) resulted in incomplete paraplegia from fracture and subluxation of T4. Dorsal laminectomy and segmental spinal fixation were used in treatment. The segmental spinal fixation consisted of sublaminar wires attached to a contoured 316L stainless steel U-rod. The chimpanzee recovered sufficient function to allow reintroduction into the chimpanzee colony at a zoological park during the 12 months after surgery and continues to do well 24 months after surgery.

Treatment of canine blastomycosis with ketoconazole.

Four dogs with blastomycosis were treated with ketoconazole, and good results were obtained in 3 of the 4 cases. Dogs that responded to treatment had manifested a variety of the clinical forms of blastomycosis (osseous, pulmonary, lymphatic, and ocular), and all lesions in the dogs abated. There were no clinical signs or clinicopathologic evidence of adverse drug reaction or toxicosis. The results of the study suggested that ketoconazole is effective for the treatment of canine blastomycosis.

The effect of levamisole on the canine central nervous system.

Levamisole was given orally to 3 groups of dogs, totaling 56 animals. Drug administration period varied from 1 to 120 days. All animals were killed and the central nervous system was examined histologically. Lesions were found in 44 of 56 dogs. These consisted of disseminated perivascular cuffing with mononuclear cells throughout the brain and meninges. The severity of the perivascular cuffing varied considerably and could not be correlated to the length of the drug administration period nor to any other variables. There was no damage to the neural tissues associated with the perivascular cuffing. There was evidence of regression of the lesions whether levamisole treatment was continued or not. The changes observed in this study were considered to be related to the known immunomodulating properties of levamisole. The pathogenesis of this change in uncertain.