Understanding the mechanical behaviour of human enamel from its structural and compositional characteristics

He, Long; Swain, Michael V.

doi:10.1016/j.jmbbm.2007.05.001

Cited by 321 publications

(184 citation statements)

References 69 publications

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“…However, enamel works differently owing to its different bonding mechanism. Individual hydroxyapatite crystallites are glued together by a thin protein layer (no more than 2 nm thick) that holds the crystallites on the surface with its elastic polymeric backbone (24,25). Crystallites can only change position by breaking the protein layer; the crystallites do not link back up unless new proteins are formed, which is possible but may require that teeth be soaked in water or saliva for hours (26)(27)(28), during which Brownian motion cannot allow the nanometer-scale debris to sit still nearby.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

New model to explain tooth wear with implications for microwear formation and diet reconstruction

Xia

Zheng

Huang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

105

114

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Paleoanthropologists and vertebrate paleontologists have for decades debated the etiology of tooth wear and its implications for understanding the diets of human ancestors and other extinct mammals. The debate has recently taken a twist, calling into question the efficacy of dental microwear to reveal diet. Some argue that endogenous abrasives in plants (opal phytoliths) are too soft to abrade enamel, and that tooth wear is caused principally by exogenous quartz grit on food. If so, variation in microwear among fossil species may relate more to habitat than diet. This has important implications for paleobiologists because microwear is a common proxy for diets of fossil species. Here we reexamine the notion that particles softer than enamel (e.g., silica phytoliths) do not wear teeth. We scored human enamel using a microfabrication instrument fitted with soft particles (aluminum and brass spheres) and an atomic force microscope (AFM) fitted with silica particles under fixed normal loads, sliding speeds, and spans. Resulting damage was measured by AFM, and morphology and composition of debris were determined by scanning electron microscopy with energy-dispersive X-ray spectroscopy. Enamel chips removed from the surface demonstrate that softer particles produce wear under conditions mimicking chewing. Previous models posited that such particles rub enamel and create ridges alongside indentations without tissue removal. We propose that although these models hold for deformable metal surfaces, enamel works differently. Hydroxyapatite crystallites are "glued" together by proteins, and tissue removal requires only that contact pressure be sufficient to break the bonds holding enamel together. dental microwear | diet reconstruction | tooth wear

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Section: Discussionmentioning

confidence: 99%

“…5). Contact pressures associated with human mastication have been reported to vary between ∼0 GPa and ∼2.5 GPa (25). As such, tests here have been conducted using the maximum Hertzian contact pressures of ∼0.74 GPa to ∼1.61 GPa.…”

Section: Methodsmentioning

confidence: 99%

New model to explain tooth wear with implications for microwear formation and diet reconstruction

Xia

Zheng

Huang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

105

114

View full text Add to dashboard Cite

show abstract

“…Studies have reported that both the hardness and the elastic modulus increase from the DEJ toward the tooth surface (Cuy et al, 2002, He andSwain, 2009). Moreover, the H and E values obtained from an occlusal section of enamel are generally higher than those obtained from an axial section (Xu et al, 1998, He andSwain, 2008). The orientation of the prism, the spatial variations in the enamel chemistry, and the mineral contents are hypothesized to contribute to these variations (Kodaka et al, 1992;Cuy et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution of the human enamel fracture toughness with aging

Zheng

Song

et al. 2013

Journal of the Mechanical Behavior of Biomedical Materials

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Enamel AgingMineral content a b s t r a c t A better understanding of the fracture toughness (KIC) of human enamel and the changes induced by aging is important for the clinical treatment of teeth cracks and fractures. We conducted microindentation tests and chemical content measurements on molar teeth from "young" (18≤age≤25) and "old" (55≤age) patients. The KIC and the mineral contents (calcium and phosphorus) in the outer, the middle, and the inner enamel layers within the cuspal and the intercuspal regions of the crown were measured through the Vickers toughness test and Energy Dispersive X-Ray Spectroscopy (EDS), respectively. The elastic modulus used for the KIC calculation was measured through atomic force microscope (AFM)-based nanoindentation tests. In the outer enamel layer, two direction-specific values of the KIC were calculated separately (direction I, crack running parallel to the occlusal surface; direction II, perpendicular to direction I). The mean KIC of the outer enamel layer was lower than that of the internal layers (po0.05). No other region-related differences in the mechanical properties were found in both groups. In the outer enamel layer, old enamel has a lower KIC, II and higher mineral contents than young enamel (po0.05). The enamel surface becomes more prone to cracks with aging partly due to the reduction in the interprismatic organic matrix observed with the maturation of enamel.

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“…In contrast to other calcified elements of the human skeleton system, enamel cannot be easily restored. Therefore, it has to be hard and durable [7].…”

Section: Structure Of Enamelmentioning

confidence: 99%

Natural and Controlled Demineralization for Study Purposes in Minimally Invasive Dentistry

Skucha-Nowak¹,

Gibas²,

Tanasiewicz³

et al. 2015

Adv Clin Exp Med

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Artificially induced demineralization of enamel is frequently used during laboratory tests, particularly in minimally invasive dentistry. The aim of this study was to analyze demineralization techniques of hard tooth tissue applicable in the research of materials in minimally invasive dentistry. The most important factor taken into consideration when designing a method is to make a model as closely similar to the natural environment of the human oral cavity as it is possible. In vitro models allow us to maintain stability and control over the environment and guarantee repeatability of the results. There are main models to produce dental caries outside of the body. The first model is chemical and it uses acids. It is simplified and reflects the actual environment of the oral cavity to a lesser degree. The second model is biological and it is more accurate as it uses microorganisms which build the dental plaque. Among in vitro protocols are also used pH-cycling models. Based on the available literature, it was found that bovine teeth and human teeth with demineralization diagnosed while still inside the oral cavity are the most frequently used kind of specimens in research conducted with use of the chemical model. Not a single case of use of the biological and pH-cycling models were found in the available literature related to the research of infiltrants in minimally invasive dentistry (Adv Clin Exp Med 2015, 24, 5, 891-898).

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Understanding the mechanical behaviour of human enamel from its structural and compositional characteristics

Cited by 321 publications

References 69 publications

New model to explain tooth wear with implications for microwear formation and diet reconstruction

New model to explain tooth wear with implications for microwear formation and diet reconstruction

Spatial distribution of the human enamel fracture toughness with aging

Natural and Controlled Demineralization for Study Purposes in Minimally Invasive Dentistry

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