Fracture in teeth-a diagnostic for inferring bite force and tooth function

Lee, James J.-W.; Constantino, Paul J.; Lucas, Peter W.; Lawn, Brian R.

doi:10.1111/j.1469-185x.2011.00181.x

Cited by 68 publications

(74 citation statements)

References 116 publications

(204 reference statements)

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“…The relationship between crack extension and force is known, with a dependence on enamel toughness and thickness, but additionally on the square root of tooth size. The presence of lamellae can be used to establish a history of force use on a tooth [76]. …”

Section: Macrofracturementioning

confidence: 99%

The Wear and Tear of Teeth

Lucas¹,

Casteren²

2014

Med Princ Pract

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A review is presented of the mechanical damage suffered by tooth crowns. This has been the subject of much recent research, resulting in a need to revise some of the thinking about the mechanisms involved. Damage is classified here by scale into macro-, meso- and microfracture. The focus is on the outer enamel coat because this is the contact tissue and where most fractures start. Enamel properties appear to be tailored to maximize hardness, but also to prevent fracture. The latter is achieved by the deployment of developmental flaws called enamel tufts. Macrofractures usually appear to initiate as extensions of tufts on the undersurface of the enamel adjacent to the enamel-dentine junction and extend from there into the enamel. Cracks that pass from the tooth surface tend to be deflected by an enamel region of high toughness; if they find the surface again, a chip (mesofracture) is produced. The real protection of the enamel-dentine junction here is the layer of decussating inner enamel. Finally, a novel analysis of mechanical wear (microfracture) suggests that the local toughness of the enamel is very important to its ability to resist tissue loss. Enamel and dentine have contrasting behaviours. Seen on a large scale, dentine is isotropic (behaving similarly in all directions) while enamel is anisotropic, but vice versa on a very small scale. These patterns have implications for anyone studying the fracture behaviour of teeth.

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Section: Macrofracturementioning

confidence: 99%

The Wear and Tear of Teeth

Lucas¹,

Casteren²

2014

Med Princ Pract

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“…This trade-off between function and damage control should be of less importance in animals that frequently replace teeth, such as reptiles or fish [23]. For example, the microstructure of tooth materials differs in non-mammals, with enamel crystals that are not arranged to deflect crack propagation [26].…”

Section: Discussionmentioning

confidence: 99%

“…As the shells had different morphologies and were quite different in shell thickness, we also calculated the force to initiate crack propagation per unit volume (F/V in N cm 23 ) of each shell by dividing the initial load of failure by the volume of material rsif.royalsocietypublishing.org J. R. Soc. Interface 11: 20131053 that was used to make the shell.…”

Section: Tests and Analysismentioning

confidence: 99%

How to best smash a snail: the effect of tooth shape on crushing load

Crofts

Summers

2014

J. R. Soc. Interface.

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Organisms that are durophagous, hard prey consumers, have a diversity of tooth forms. To determine why we see this variation, we tested whether some tooth forms break shells better than others. We measured the force needed with three series of aluminium tooth models, which varied in concavity and the morphology of a stress concentrating cusp, to break a shell. We created functionally identical copies of two intertidal snail shells: the thicker shelled Nucella ostrina and the more ornamented Nucella lamellosa using a three-dimensional printer. In this way, we reduced variation in material properties between test shells, allowing us to test only the interaction of the experimental teeth with the two shell morphologies. We found that for all tooth shapes, thicker shells are harder to break than the thinner shells and that increased ornamentation has no discernible effect. Our results show that for both shell morphologies, domed and flat teeth break shells better than cupped teeth, and teeth with tall or skinny cusps break shells best. While our results indicate that there is an ideal tooth form for shell breaking, we do not see this shape in nature. This suggests a probable trade-off between tooth function and the structural integrity of the tooth.

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“…However, provided longitudinal cracks remain fully contained within the enamel coat, structural integrity may not be seriously impaired. After all, typical postcanine teeth in mammals contain a myriad of such cracks, and cracked teeth can last a lifetime [31]. Teeth are 'built to last' [11].…”

Section: Multi-cusp Complexity Allows For Enhanced Food Manipulationmentioning

confidence: 99%

On the evolutionary advantage of multi-cusped teeth

Constantino

Bush

Barani

et al. 2016

J. R. Soc. Interface.

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A hallmark of mammalian evolution is a progressive complexity in postcanine tooth morphology. However, the driving force for this complexity remains unclear: whether to expand the versatility in diet source, or to bolster tooth structural integrity. In this study, we take a quantitative approach to this question by examining the roles of number, position and height of multiple cusps in determining sustainable bite forces. Our approach is to use an extended finite-element methodology with due provision for stepby-step growth of an embedded crack to determine how fracture progresses with increasing occlusal load. We argue that multi-cusp postcanine teeth are well configured to withstand high bite forces provided that multiple cusps are contacted simultaneously to share the load. However, contact on a single near-wall cusp diminishes the strength. Location of the load points and cusp height, rather than cusp number or radius, are principal governing factors. Given these findings, we conclude that while complex tooth structures can enhance durability, increases in cusp number are more likely to be driven by the demands of food manipulation. Structural integrity of complex teeth is maintained when individual cusps remain sufficiently distant from the side walls and do not become excessively tall relative to tooth width.

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Fracture in teeth-a diagnostic for inferring bite force and tooth function

Cited by 68 publications

References 116 publications

The Wear and Tear of Teeth

The Wear and Tear of Teeth

How to best smash a snail: the effect of tooth shape on crushing load

On the evolutionary advantage of multi-cusped teeth

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