Surface fine structure of treated dentine investigated with tapping mode atomic force microscopy (TMAFM)

Objectives: the objective of this study was to investigate the surface morphology and roughness of human dentine treated with different dentine conditioning agents with tapping mode atomic force microscopy (TMAFM). Methods: dentine samples from third permanent molar teeth were prepared as flat disks. The samples were treated with different conditioning agents for 15–30 s: aqueous phosphoric acid and those supplied with three commercial adhesive products. The surface morphology and roughness was measured with tapping mode atomic force microscopy, a highly resolving method which minimises unwanted side effects of conventional AFM. Results: the tubules, the areas between the tubules and the entire surface showed variations in surface morphology and roughness, depending on the conditioning agent used. These differences might affect the bonding properties of the agents in dentine/polymer systems. Conclusions: the surface structure, such as the tubules diameters and depths, the local height differences of the surface between the tubules and the overall mean surface roughness Ra varies between samples treated with different conditioning agents. All conditioning agents, however, led to exposed and open tubules. Clinical relevance: the direct observation of effects of conditioning agents on dentine is important in order to judge their performance under clinically relevant conditions-free of desiccation artefacts. A vast number of conditioning agents is available today. The differences in their actual effects on dentine surfaces, however, are less than clear to many users.