Ultrastructural localisation of TGF-beta exposure in dentine by chemical treatment

Transforming growth factor-beta (TGF-beta) sequestered in dentine matrix ha s an important role in dental tissue repair after injury and its exposure a t sites of injury may stimulate tertiary dentinogenesis. This study aimed t o investigate the expression of TGF-beta isoforms in mature human dentine m atrix and the ability of chemical treatments to expose TGF-beta on the cut surface of dentine using gold immunolabelling and subsequent scanning elect ron microscopy examination. TGF-beta 1 was the only isoform that could be d etected in human dentine and the nature of the chemical treatment of the ti ssue influenced its detection. EDTA treatment provided good exposure of TGF -beta 1 on the dentine surface, whilst citric acid and sodium hypochlorite treatments revealed lesser amounts of this isoform. Only minimal staining f or TGF-beta 1 was observed in samples treated with phosphate-buffered salin e. TGF-beta 2 and -beta 3 could not be detected in the specimens with any o f the treatments. This study suggests that TGF-beta 1 is the only TGF-beta isoform expressed by human odontoblasts to be sequestered in dentine implyi ng that differences in isoform-extracellular matrix interactions may exist. Information on chemical treatment of tissue specimens for immunostaining m ay provide a useful basis for selection of tissue preparation techniques fo r clinical restorative treatment procedures to facilitate TGF-beta mediated reparative processes at sites of dental injury.