Healing of onlay mandibular bone grafts covered with collagen membrane or bovine bone substitutes: a microscopical and immunohistochemical study in the sheep.

The objective of this study was to evaluate the role of collagen membrane and Bio-Oss coverage in healing of an onlay graft to the mandible. Twelve adult sheep each received an onlay bone graft (experiment 1), bone graft+Bio-Gide (experiment 2), and bone graft+Bio-Oss/Bio-Gide (experiment 3) on the lateral surface of the mandible. The animals were euthanized at 4, 8, 12 or 16 weeks after surgery, and findings were analysed by routine microscopy and immunohistochemistry for proliferation (Ki67) and apoptotic (Caspase-3) markers. Grafts were fully incorporated in all specimens. Pronounced resorption was observed in experiment 1. Minimal loss of graft volume was seen in experiment 2 specimens without membrane displacement. A remarkable increase in the augmented region of the mandible was observed in experiment 3. A high number of osteoclasts were expressed within the grafts during the early healing period, and thereafter declined markedly. Osteoblasts within the grafts expressed a moderate level of Ki67 at 8 weeks, which thereafter declined markedly. The strongest expression of Caspase-3 on the bone surface was observed after 16 weeks. In conclusion, the effect of collagen membrane coverage on bone graft volume maintenance was dependent on membrane stability during healing. An autogenous bone graft covered with Bio-Oss particles resulted in a remarkable increase in augmented lateral surface of the mandible. The late stage of bone graft healing was associated with a high apoptotic induction pathway of osteoblasts lining the surfaces of the new bone, demonstrated by strong positive Caspase-3 immunoreactivity.

A case of chronic calcium pyrophosphate dihydrate crystal disease (tophaceous pseudogout) in the temporomandibular joint.

Pseudogout is a rare joint disease which is characterized by the presence of calcium pyrophosphate dihydrate crystals in the intraarticular and periarticular tissue. The crystals tend to attach to fibrocartilage tissue. Pseudogout principally affects the knee and wrist joints. Involvement of the temporomandibular joint (TMJ) is very rare. There have been <20 cases reported world-wide. Both acute and chronic manifestations have been described. We present here an unusual case that necessitated a high condylectomy.

Chemoprevention of oral squamous cell carcinomas.

Among individuals with a history of head and neck cancer and tobacco abuse the risk of second primary cancers in the upper aerodigestive tract is high. Chemoprevention of oral squamous cell carcinomas is based on two conditions: Premalignant mucosa lesions are treated with chemopreventive agents in order to prevent malignant conversion (primary prevention). In secondary prevention of oral cancer, after curative therapy patients are treated by chemoprevention in order to reduce the rate of second primaries. This paper presents a comprehensive clinical review of oral cancer prevention studies, highlighting the agents mostly used, such as beta-carotene, alpha-tocopherol, ascorbic acid, and retinoids. Although most intervention trials showed good overall response with these substances, high relapse rates and serious side effects, in most cases related to the retinoid compounds were noticed. In addition, in all prospective randomized chemoprevention trials (CARET, ATBC and PHS) no significant evidence of benefit for supplementation with alpha-tocopherol, beta-carotene or retinyl palmitate was reported.