Amelogenin control over apatite crystal growth is affected by the pH and degree of ionic saturation S Habelitz PK DenBesten SJ Marshall GW Marshall W Li Authors' affiliations: Stefan Habelitz, Sally J. Marshall, Grayson W. Marshall, Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, CA, USA Pamela K. DenBesten, Wu Li, Department of Growth and Development, University of California, San Francisco, CA, USA Correspondence to: Stefan Habelitz Department of Preventive and Restorative Dental Sciences University of California 707 Parnassus Avenue D-2260 San Francisco CA 94143-0758 USA Tel.: 415 514 0818 Fax: 415 476 0358 E-mail: shabeli@itsa.ucsf.edu Structured Abstract Authors – Habelitz S, DenBesten PK, Marshall SJ, Marshall GW, Li W Objective – To study the mechanisms which promote the interactions of amelogenin proteins with the forming mineral to establish suitable conditions for the biomimetic synthesis of enamel in vitro. Design – Saturated calcium phosphate solutions were used in conjunction with recombinant amelogenin proteins to induce mineral formation on glass-ceramics substrates containing oriented fluoroapatite crystals (FAP). The height of mineral layers formed on these substrates within 24 h was measured by atomic force microscopy (AFM). Experimental Variables – The effect of protein concentration, pH and degree of saturation (DS) on the growth of apatite mineral was evaluated. Mineralization experiments were performed at 0, 0.4 and 1.6 mg/ml amelogenin concentrations. Mineralization solutions were used at pH values of 6.5, 7.4, 8.0 and 8.8 and DS of calcium and phosphate between 9 and 13. Outcome Measure – Height and morphology of mineralized layer formed on glass-ceramic substrates as determined from AFM measurements. Results – Homogeneous nucleation and crystal growth of thin layers on the FAP were observed, when calcium and phosphate ions were added. The height of these layers grown on (001) planes of FAP was strongly dependent on the protein concentration and pH. At concentrations of 0 and 0.4 mg/ml crystal grew 5–15 nm on the FAP, while they grew approximately to 200 nm at 1.6 mg/ml. The enhanced crystal growth was observed only at pH 6.5, 7.4 and 8.0, while layers only 20 nm thick were obtained at pH 8.8. An increase in DS resulted in uncontrolled growth of calcium phosphate mineral covering large areas of the substrate. Conclusions – Protein concentration, pH and the saturation of the mineralizing solution need to be considered carefully to Dates: Accepted 10 August 2005 To cite this article: Orthod Craniofacial Res 8, 2005; 232–238 Habelitz S, DenBesten PK, Marshall SJ, Marshall GW, Li W: Amelogenin control over apatite crystal growth is affected by the pH and degree of ionic saturation Copyright Ó Blackwell Munksgaard 2005