LIGHT-MICROSCOPIC INVESTIGATION OF THE DISTRIBUTION OF EXTRACELLULAR-MATRIX MOLECULES AND CALCIFICATIONS IN HUMAN DENTAL PULPS OF VARIOUS AGES

The distribution of extracellular matrix molecules, especially collage n types I, III, V, and VI, in the extracellular matrix of the connecti ve tissue of human dental pulp of various ages was studied by polariza tion and indirect immunofluorescence microscopy by using a conventiona l fluorescence microscope and a confocal laser scanning microscope. Po larization and immunofluorescence microscopy of paraffin sections show ed thick fibers of collagen type I, which represented the main compone nt of the connective tissue matrix of the dental pulp. By indirect imm unofluorescence, thin fibers and small bundles of collagen type III we re determined to be one of the main fibrillar elements present in the dental pulp matrix. Collagen type IV was detected by a clear intense s taining of the basement membrane of blood vessels at all ages examined . Collagens type V and VI formed a dense meshwork of thin microfibrils throughout the stroma of the connective tissue of the dental pulp. Th ese fibers were localized around blood vessels and appeared to be enri ched in the subodontoblastic layer. Investigations by means of confoca l laser scanning microscopy revealed fibers of collagen type VI spiral ling between fully differentiated odontoblasts toward the predentin la yer. With advancing age, the connective tissue matrix appeared to be c ondensed and aggregates of thick fiber bundles could be observed. Furt hermore, the participation of various collagen types in the compositio n of pulp stones was shown. These calcifications and diffuse calcifica tions increased in frequency with advancing age in a statistically sig nificant manner.