An atomic force microscopic study of the ultrastructure of dental enamel afflicted with amelogenesis imperfecta

Abstract

The ultrastructure of human tooth enamel from a patient diagnosed to have amelogenesis imperfecta (AI) was investigated using atomic force microscopy (AFM) and compared with normal human tooth enamel. AI is a hereditary defect of dental enamel in which the enamel is deficient in either quality or quantity. Tissue-specific proteins, especially amelogenins, have been postulated to play a central role in amelogenesis. The secondary structure of amelogenin has been assigned an important role in directing the architecture of hydroxyapatite (HA) enamel crystallites and an alteration of the secondary structure of amelogenin is expected to result in an altered architecture of the mineral phase in human enamel. Previous studies have shown that the human amelogenin gene encodes for a mutant protein in which a conserved Pro is mutated to a Thr residue (Pro-->Thr); such a mutation should be expected to cause a disoriented pattern of the mineral phase in enamel. AFM results presented for the AI tooth enamel clearly demonstrate that the apatite crystal morphology in AI tooth enamel is perturbed in the diseased state; this might result from a defective synthesis of the extracellular matrix proteins, e.g. amelogenin, by the ameloblasts.

Enamel sample preparation for AFM: Influence on roughness and morphology

“…This tissue represents the first barrier to damage for teeth. There are several studies that have focused on experiments and analysis of enamel, but there has been difficulty in standardizing the parameters, and therefore, in comparing the results (Agrawal et al, ; Batina et al, ; Cheng et al, ; Choi et al, ; Cui and Ge, ; Farina et al, ; Finke et al, ;Ge et al, ; Guidoni et al, ; Lippert et al, 2004; Loyola‐Rodriguez et al, 2009; Mahmoud, Ahmed, Mahmoud, Grawish and Zaher, ; Parkinson, Shahzad and Rees, ; Sanches et al, ; Wang et al, ).…”

“…Enamel's unique microstructure can be seen upon direct observation of the surface as shown by the images of Group I; however, only a few authors have used native enamel in their experiments (Batina et al, ; Farina et al, ; Finke et al, ; Lippert et al, 2004; Tanaka, Shibata, Manabe, and Miyazaki, ; Vargas‐Koudriavtsey and Herrera‐Sancho, 2017). The most used pretreatments in the literature are grinding and polishing because the values for the initial roughness are standardized, which is confirmed by the lowest standard deviation among the groups (Agrawal et al, ; Cheng et al, ; Choi et al, ; Cui and Ge, ; Ge et al, ; Guidoni et al, ; Lippert et al, 2004; Loyola‐Rodriguez et al, 2009; Mahmoud et al, 2012; Parkinson, Shahzad and Rees, ; Sanches et al, ; Wang et al, ).…”

“…AFM is a suitable tool to evaluate the morphological changes on the surface and to observe the microstructure and stages of demineralization of enamel (Agrawal et al, ; Batina et al, , ; Cheng et al, ; Finke et al, ). AFM provides high‐contrast, quantitative data on the nanometer level in all three dimensions, producing high‐resolution images, especially in the z ‐direction, and it is an important tool to obtain structural information and information about surface changes.…”

“…AFM is a suitable tool to evaluate the morphological changes on the surface and to observe the microstructure and stages of demineralization of enamel (Agrawal et al, 2014;Batina et al, 2002Batina et al, , 2004Cheng et al, 2009;Finke et al, 2000). Pedraza, 2011;Sanches et al, 2009).…”

“…Agrawal et al, 2014;Batina et al, 2002Batina et al, ,2004Cheng et al, 2009;Choi et al, 2010;Cui and Ge, 2007;Farina et al, 1999;Finke et al, 2000;Ge et al, 2005;Guidoni et al, 2008;Lippert et al, 2004; Loyola-Rodriguez et al, 2009;Mahmoud, Ahmed, Mahmoud, Grawish and Zaher, 2012;Parkinson, Shahzad and Rees, 2010;Sanches et al, 2009;Wang et al, 2005).Enamel's unique microstructure can be seen upon direct observation of the surface as shown by the images of Group I; however, only a few authors have used native enamel in their experiments(Batina et al, 2002(Batina et al, ,2004Farina et al, 1999;Finke et al, 2000;Lippert et al, 2004;Tanaka, Shibata, Manabe, and Miyazaki, 2010; Vargas- Koudriavtsey and Herrera-Sancho, 2017). The most used pretreatments in the literature are grinding and polishing because the values for the initial roughness are standardized, which is confirmed by the lowest standard deviation among the groups(Agrawal et al, 2014;Cheng et al, 2009;Choi et al, 2010;Cui and Ge, 2007; al., 2005; Guidoni et al, 2008; Lippert et al, 2004; Loyola-Rodriguez et al, 2009; Mahmoud et al, 2012; Parkinson, Shahzad and Rees, 2010; Sanches et al, 2009; Wang et al, 2005).…”