Cementum is the mineralized structure that covers the surface of the roots of teeth; it serves as the attachment site for collagen fibers of adjacent soft connective tissues. Very little is known about how cementum formation is regulated or how it affects other periodontal structures. We have raised a monoclonal antibody that may aid in studies to determine the biology and function of cementum. Mice were immunized with a 55-kDa attachment protein partially purified from human cementum and a monoclonal antibody, H166, was produced. Incubation of tissue sections with this antibody and fluorescein isothiocyanate-conjugated secondary antibody revealed that it immunostains cementum but not dentin, gingiva, or periodontal ligament. Alveolar bone did not bind the antibody, although a few paravascular cells were positive. Long bones, kidney, liver, skin, and several other tissues were negative. Protein fractions separated from cementum extracts by binding to immobilized H166 column contained 55-, 49-, 39-, 29- to 31-, and 23- to 26-kDa components that cross-reacted with the antibody in Western blots; these components were previously shown to be derived from a common precursor. We conclude that the antibody recognizes a group of proteins related to 55-kDa attachment protein in cementum. Our data show that the antibody could serve as a marker for cementum.

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Cells obtained from human cementoblastoma and alveolar bone were isolated and cultured. Initial and late stages of mineralization were assessed by using atomic force microscopy, scanning electron microscopy and X‐ray microanalysis. In cultures of cementoblastoma‐derived cells the initial stages of mineralization showed well‐defined spherical‐shaped structures, while the osteoblastic cells showed plaque‐like deposits. These morphological patterns of mineral deposition could serve as nucleation centers for hydroxyapatite crystals. Late stages of mineralization at 28 and 35 d maintained thosemorphological differences established in initial cultures. The material deposited by cemetoblastoma and osteoblastic cells, analyzed by EDX spectra, revealed similar Ca/P ratios for both cell types. These values were similar to those reported for hydroxyapatite in enamel and bone. Alkaline phosphatase specific activity (Alp), of osteoblastic cells at 3, 7 and 11 d, showed an increase of 27.9, 50.9 and 37.0% (p<0.001), respectively. However, at 15 and 19 d there was an increase of A1P activity of cementoblastoma cells by 39.4 and 34.5% over osteoblastic cells (p <0.001). Immunostaining of cementoblastorna and osteoblastic cells using a specific mAb against a cementum‐derived attachment protein revealed strong immunostaining of cementoblastoma cells which was localized to the cell membrane and fibril‐like structures (96.2±1.3). A few osteoblastic cells also stained weakly with the anti‐CAP mAb (6.4 ±0.6). Sections of decalcified paraffin embedded cementoblastoma specimens, when immunostained with anti‐CAP mAb, showed strong immunostaining of the cells surrounding the regular and irregularly‐shaped calcified masses of the tumor. Putative cementocytes also stained positively. Immunostaining with a polyclonal antibody against osteopontin strongly stained the osteoblastic cells (89.0±3.6). Cementoblastoma cells showed weaker staining (54.252.4). The results suggest that cementoblastoma cells could be a major source of specific cementum proteins. These cells could provide the opportunity to elucidate the regulation of the cementogenesis process.