The long bone deformity of osteogenesis imperfecta III: analysis of structural changes carried out with scanning electron microscopic morphometry.

The wedges of the mid-diaphyseal osteotomies carried out to correct the femoral and/or tibial native deformity in type III osteogenesis imperfecta (OI III) were used to study the remodeling patterns and lamellar organization at the level of the major deformity. Histology and scanning electron microscopy (SEM) morphology showed abnormal cortical remodeling characterized by the failure to form a cylinder of compact bone with a regular marrow canal. Atypical, flattened, and large resorption lacunae with a wide resorption front on one side and systems of parallel lamellae on the opposite side were observed, resembling those formerly reported as drifting osteons. SEM morphometry documented a higher percentage of nonossified vascular/resorption area (44.3 %) in OI than in controls (13.6 %), a lower density of secondary osteons, and lower values for the parameters expressing the individual osteon size. The mean osteon total area, the mean central canal area, and the mean osteon bone area of two selected, randomized populations of secondary osteons were significantly higher (p < 0.001, p = 0.028, and p < 0.001, respectively) in control bones than in OI. The mean ossified matrix area was not significantly different, but the mean secondary osteon number and mean density were higher in controls (both p < 0.001). Osteon wedges were carried out to correct the native deformity of OI III and morphologic analysis suggested that the abnormal remodeling pattern (with "drifting osteons") may result from the altered load and tensile stresses on the deformed tubular bones.

Dentinogenesis imperfecta in children with osteogenesis imperfecta: a clinical and ultrastructural study.

AIM: The aim of this study was to assess the correlation between osteogenesis imperfecta (OI) and dentinogenesis imperfecta (DI) from both a clinical and histological point of view, particularly clarifying the structural and ultrastructural dentine changes. DESIGN: Sixteen children (6-12 years aged) with diagnosis of OI were examined for dental alterations referable to DI. For each patient, the OI type (I, III, or IV) was recorded. Extracted or normally exfoliated primary teeth were subjected to a histological examination (to both optical microscopy and confocal laser-scanning microscopy). RESULTS: A total of ten patients had abnormal discolourations referable to DI: four patients were affected by OI type I, three patients by OI type III, and three patients by OI type IV. The discolourations, yellow/brown or opalescent grey, could not be related to the different types of OI. Histological exam of primary teeth showed severe pathological change in the dentin, structured into four different layers. A collagen defect due to odontoblast dysfunction was theorized to be on the base of the histological changes. CONCLUSIONS: There is no correlation between the type of OI and the type of discolouration. The underlying dentinal defect seems to be related to an odontoblast dysfunction.