Multinucleated giant cells elicited around hydroxyapatite particles implanted in craniotomy defects are not osteoclasts.

BACKGROUND: The nature of the multinucleated giant cells (MNGC) elicited in contact with implantable biomaterials is still indecisive. METHOD: In Wistar rats the MNGC recruited after the implantation of hydroxyapatite (HA) particles in standardized skull defects were examined morphologically (at both the light and electron microscope levels), enzymatically (tartrate-resistant acid phosphatase and non-specific esterase), and after a challenge with salmon calcitonin. RESULTS: The MNGC were of great size and contained abundant mitochondria, vacuoles, and vesicles throughout the cytoplasm; they were either tightly apposed to the HA surface or had long and thin processes penetrating the material. When processed for tartrate-resistant acid phosphatase, only a few cells were weakly stained. The staining was totally suppressed when samples were pretreated with cyanuric chloride in the MNGC but not in the host osteoclasts. Calcitonin induced the withdrawal of the host osteoclasts from the bone surface while the MNGC remained in contact with the HA material. CONCLUSION: The MNGC recruited to HA particles did not exhibit the morphologic, enzymatic and functional characteristics of the osteoclasts, and consequently must be regarded as macrophage polykaryons.

[Posterior bite collapse. 2. Therapeutic proposals]. / L'effondrement occlusal postérieur. 2ème partie. Propositions therapeutiques.

In the treatment of posterior bite collapse, the orthodontic phase consists of three steps: uprighting of molar teeth, leveling of the mandibular arch and closure of anterior diastemas. During and after orthodontic therapy, the maintenance of periodontal health is important. For patients in which there is a reduced periodontium, splinting should be accomplished after the teeth are moved into their desired position.

Periodontal and femoral bone status in periodontitis-affected hamsters receiving a high dose indomethacin treatment.

The aim of this study was to test the effect of a high dose (6 mg/kg/d) of indomethacin, a PG-synthesis inhibitor, on hamster periodontitis and to verify a possible systemic skeletal action. Thirty animals were separated into three groups: control, untreated periodontitis-affected, and indomethacin treated groups. Compared to affected untreated animals, indomethacin reduced the number of osteoclasts (p less than 0.001) to the control level, and accordingly the extent of resorption (p less than 0.01). A partial decrease in reversal (p less than 0.05) was also obtained; the persistence of aborted reversal lacunae was the scar of the pretreatment period. The extent of formation was markedly increased by indomethacin (p less than 0.01). Bacterial plaque accumulation was not modified but PMNLs investing plaque were dramatically decreased (p less than 0.02). Indomethacin had no influence on the femoral periosteal remodeling, nor on metaphyseal and epiphyseal trabecular density, nor on growth plate thickness. These results confirm the positive effect of indomethacin on hamster periodontitis and emphasize the role of PGs on periodontitic bone disturbances, particularly on the uncoupling of the remodeling sequence. The reduction in PMNL migration is an important feature, which possibly participates in the improvement of the bone status. The lack of femoral changes indicates that a mid-term treatment with indomethacin has no detrimental action on ordered skeletal growth and bone mass.

[Posterior bite collapse. 1. Etiology and diagnosis]. / L'effondrement occlusal postérieur. 1re partie: Etiologie et diagnostic.

The posterior Bite Collapse is a sequelae of advanced break down. The presence of periodontal inflammation and loss of osseous support can induce teeth migration in a direction partially imposed by occlusal forces. Posterior Bite Collapse often causes mesial drifting of the posterior teeth and flaring of the anterior segments. It may be aggravated by early loss of teeth that are not replaced, by malocclusion or by a neuro muscular disorder.