IMMUNOREACTIVITY OF TENASCIN-C IN DENTIN MATRIX IN DENTINOGENESIS IMPERFECTA ASSOCIATED WITH OSTEOGENESIS IMPERFECTA

Osteogenesis imperfecta (OI) is a heterogeneous group of heritable con nective tissue disorders, assigned to different mutations in type I co llagen genes. A variety of structural abnormalities of dentin have bee n described in dentinogenesis imperfecta (DI) associated with OI. To c larify further the constitution of the dentin matrix in OI, we immunos tained frozen and paraffin sections of deciduous teeth from four patie nts, each from a different family, with two monoclonal antibodies (MAb s) to the matrix glycoprotein tenascin-C (TN-C). One of the MAbs recog nizes an epitope common to all TN-C isoforms (BC-4), and the other is specific for a splicing variant (BC-2). Normal teeth, oral mucosa, and skin were analyzed for comparison. Staining patterns with the two MAb s did not differ markedly. Normal dentin matrix and odontoblasts were lacking reactivity, but the pulp stained clearly. TN-C reactivity was present in the dentin matrix of all teeth obtained from two patients w ith different OI phenotypes and DI, and in one out of three teeth from one patient who also had DI. The reactivity was distributed in layers , but the staining patterns varied from one patient to another and fro m tooth to tooth. Intratubular staining seen in a tooth from the patie nt with clinically and histologically normal teeth was comparable with that present in normal deciduous teeth. The variation in TN-C express ion suggests that, besides genetic heterogeneity, epigenetic factors c ould influence the composition of the dentin matrix in OI.