Microhardness and microstructure of deciduous enamel with different types of amelogenesis imperfecta
Amelogenesis imperfecta (AI) is an inherited tooth disorder with widely varying phenotypes. The aim of this study was to determine the microhardness and microstructure characteristics of the enamel in AI teeth. The AI phenotypes examined were hypoplastic (pitted and smooth form), hypomaturated, and hypocalcified. Six AI patients were diagnosed according to clinical characteristics. The microhardness of the enamel was measured on axial cuts of AI teeth acquired from the patients. The measurements were done on several sites from the enamel surface towards the dentine-enamel junction using the Vickers scale. Values of microhardness were compared to corresponding control teeth. The microstructure of AI enamel types was evaluated using scanning electron microscopy. The values of microhardness in pitted hypoplastic AI samples were, on average, lower compared to the control enamel and dropped markedly towards the dentine-enamel junction. The smooth hypoplastic enamel was not only extremely thin but also much softer than control enamel. The values for hypomaturated AI fluctuated, but the palatal sites were markedly softer than in the control tooth. Hypocalcified enamel was the softest, with values resembling those of dentin. Microstructural changes varied from altered orientation of enamel prisms in pitted hypoplastic AI to lack of normal prismatic structure and severe porosity in hypocalcified AI. The present results suggest different microhardness profiles and microstructures in each phenotype. Variations among phenotypes are expected with larger case selection in this genetically heterogeneous disease.
- Laboratory of Epitaxy and Nanostructures, University of Nova Gorica, 5101, Nova Gorica, Slovenia
- Department of Materials Science and Metallurgy, Faculty of Natural Sciences and Engineering, University of Ljubljana, 1000, Ljubljana, Slovenia
- Department of Oral Medicine and Periodontology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
-  J.P. Wainmann, J.F. Svoboda and R.W. Woods: “Hereditary disturbances of enamel formation and calcification,”, J. Am. Dent. Assoc., Vol. 32, (1945), pp. 397–418.
-  M.J. Aldred and P.J.M. Crawford: “Amelogenesis imperfecta-towards a new classification,”, Oral Dis., Vol. 1, (1995), pp. 2–5. http://dx.doi.org/10.1111/j.1601-0825.1995.tb00148.x[Crossref]
-  C.J. Witkop: “Amelogenesis imperfecta, dentinogenesis imperfecta and dentin dysplasia revisited: problems in classification,”, J. Oral. Pathol., Vol. 17, (1989), pp. 547–553. http://dx.doi.org/10.1111/j.1600-0714.1988.tb01332.x[Crossref]
-  B. Bäckman, G. Anneroth and P. Hörstedt: “Amelogenesis imperfecta: a scanning electron microscopic and microradiographic study,”, Oral. Pathol., Vol. 18, (1989), pp. 140–145. http://dx.doi.org/10.1111/j.1600-0714.1989.tb00752.x[Crossref]
-  B. Bäckman and B. Angmar-Mansson: “Mineral distribution in the enamel of teeth with amelogenesis imperfecta as determined by quantitative microradiography,”, Scan. J. Dent. Res., Vol. 102, (1994), pp. 193–197.
-  B. Bäckman and G. Anneroth: “Microradiographic study of amelogenesis imperfecta,”, Scan. J. Dent. Res., Vol. 97, (1989), pp. 316–329.
-  B. Bäckman, T. Lundgren, U. Engström, L.K.L. Falk, J.M. Chabala, R. Levi-Setti and J.G. Norén: “The absence of correlations between a clinical classification and ultrastructural findings in amelogenesis imperfecta,”, Acta Odontol. Scand., Vol. 51, (1993), pp. 79–89. [Crossref]
-  J.T. Wright, T.G. Deaton, K.I. Hall and M. Yamauchi: “The mineral and protein content of enamel in amelogenesis imperfecta,”, Connect. Tissue Res., Vol. 32, (1995), pp. 247–252. [Crossref]
-  R.G. Craig and F.A. Peyton: “The microhardness of enamel and dentin,”, J. Dent. Res., Vol. 37, (1958) pp. 661–668. [Crossref]
-  N. Meredith, M. Sherriff, D.J. Setchell and S.A.V. Swanson: “Measurement of the microhardness and Young’s modulus of human enamel and dentine using an indentation technique,”, Arch. Oral. Biol., Vol. 41, (1996), pp. 539–545. http://dx.doi.org/10.1016/0003-9969(96)00020-9[Crossref]
-  H.H. Xu, D.T. Smith, S. Jahanmir, E. Romberg, J.R. Kelly, V.P. Thompson and E.D. Rekow: “Indentation damage and mechanical properties of human enamel and dentin,”, J. Dent. Res., Vol. 77, (1998), pp. 472–480. http://dx.doi.org/10.1177/00220345980770030601[Crossref]
-  D. Purdell-Lewis, A. Groeneveld and J. Arends: “Hardness tests on sound enamel and artificially demineralized white spot lesions,”, Caries Res., Vol. 10, (1976), pp. 201–205. [Crossref]
-  J.L. Cuy, A.B. Mann, K.J. Livi, M.F. Teaford and T.P. Weihs: “Nanoindentation mapping of the mechanical properties of human molar tooth enamel,”, Arch. Oral. Biol., Vol. 47, (2002), pp. 281–291. http://dx.doi.org/10.1016/S0003-9969(02)00006-7[Crossref]
-  H.F. Atkinson and P. Saunsbury: “An investigation into the hardness of human enamel,”, Br. Dent. J., Vol. 94, (1953), pp. 250–253.
-  K. Fokuda, S. Higashi, K. Miake and T. Matsui: “Studies on microhardness of the human third molar, especially that of the enamel,”, Bull. Tokyo. Dent. Coll., Vol. 16, (1975), pp. 11–33.
-  E. Mahoney, A. Holt, M. Swain and N. Kilpatrick: “The hardness and modulus of elasticity of primary molar teeth: an ultra-micro-indentation study,”, J. Dent., Vol. 28, (2000), pp. 589–594. http://dx.doi.org/10.1016/S0300-5712(00)00043-9[Crossref]
-  J.D.B. Featherstone, J.M. ten Cate, M. Shariati and J. Arends: “Comparison of artificial caries-like lesions by quantitative microradiography and microhardness profiles,”, Caries. Res., Vol. 17, (1983), pp. 385–391.
-  T. Kodaka, K. Debari, M. Yamada and M. Kuroiwa: “Correlation between microhardness and mineral content in sound human enamel,”, Caries. Res., Vol. 26, (1992), pp. 139–141. http://dx.doi.org/10.1159/000261498[Crossref]
-  J.T. Wright, C. Robinson and R. Shore: “Characterization of the enamel ultrastructure and mineral content in hypoplastic amelogenesis imperfecta,”, Oral. Surg. Oral. Med. Oral. Pathol., Vol. 72, (1991), pp. 594–601. http://dx.doi.org/10.1016/0030-4220(91)90499-3[Crossref]
-  R.C. Shore, B. Bäckman, S.J. Brookes, J. Kirkham, S.R. Wood and C. Robinson: “Inheritance pattern and elemental composition of enamel affected by hypomaturation amelogenesis imperfecta,”, Connect. Tissue. Res., Vol. 43, (2002), pp. 466–471. http://dx.doi.org/10.1080/713713459[Crossref]
-  J.T. Wright, M.J. Aldred, P.J.M. Crawford, J. Kirkham and C. Robinson: “Enamel ultrastructure and protein content in X-linked amelogenesis imperfecta,”, Oral. Surg. Oral. Med. Oral. Pathol., Vol. 76, (1993), pp. 192–199. http://dx.doi.org/10.1016/0030-4220(93)90204-H[Crossref]
-  M.J. Aldred, P.J.M. Crawford, W. Rowe and R.P. Shellis: “Scanning electron microscopic study of primary teeth in X-linked amelogenesis imperfecta,”, J. Oral. Pathol. Med., Vol. 21, (1992), pp. 186–192. http://dx.doi.org/10.1111/j.1600-0714.1992.tb00099.x[Crossref]
-  J.T. Wright and W.T. Butler: “Alteration of enamel proteins in hypomaturation amelogenesis imperfecta,”, J. Dent. Res., Vol. 86, (1989), pp. 1328–1330. [Crossref]
-  Y. Takagi, H. Fujita, H. Katano, H. Shimokawa and T. Kuroda: “Immunochemical and biochemical characteristics of enamel proteins in hypocalcified amelogenesis imperfecta,”, Oral. Surg. Oral. Med. Oral. Pathol. Oral. Radiol. Endodont., Vol. 85, (1998), pp. 424–430. http://dx.doi.org/10.1016/S1079-2104(98)90068-3[Crossref]