Mechanics analysis of molar tooth splitting

Barani, Amir; Chai, Herzl; Lawn, Brian R.; Bush, Mark B.

doi:10.1016/j.actbio.2015.01.004

Cited by 25 publications

(29 citation statements)

References 39 publications

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“…Those qualities were not identified in prior studies performed using the indentation method. Nevertheless, they could be considered most relevant to the potential for tooth fracture arising from incipient cracks on the occlusal surface of teeth [40,41]. Based on the degree of reduction in K g , the degradation in fracture resistance of enamel with age should be considered of substantial importance to tooth survival.…”

Section: Discussionmentioning

confidence: 99%

On the importance of aging to the crack growth resistance of human enamel

2016

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With improvements in oral health and an overall increase in quality of life, the percentage of fully or largely dentate seniors is increasing. Understanding the effects of aging on the mechanical properties of teeth is essential to the maintenance of lifelong oral health. In this investigation the effects of aging on the fracture toughness of human enamel were evaluated from incremental crack growth experiments performed on tissue of donor teeth representing “young” (17≤ age ≤ 25) and “old” (age ≥ 55) age groups. Results showed that the old enamel exhibited significantly lower resistance to fracture than that of the young tissue in two orthogonal directions of crack growth. For crack growth transverse to the enamel rods, the fracture toughness of the old enamel (0.37±0.15 MPa•m0.5) was nearly 70% lower than that of tissue from the young teeth (1.23±0.20 MPa•m0.5). Based on results from a mechanistic analysis of crack growth, the reduction in fracture resistance is attributed to a decreased in the degree of extrinsic toughening. The practice of restorative dentistry should account for these changes in tooth tissues in the treatment of senior patients.

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Section: Discussionmentioning

confidence: 99%

On the importance of aging to the crack growth resistance of human enamel

2016

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“…The presence of multiple cusps enhances the prospect of tooth splitting. For loading between cusps with a hard round object, a longitudinal crack can be wedged open and penetrate into the dentine sublayer to cause a split [35]. Such a fracture is clearly catastrophic, but the loads to propagate either the precursor longitudinal crack (L) or subsequent splitting crack (S) are typically well beyond normal bite forces, even for smaller indenting objects where wedging forces are greater.…”

Section: Setting Up the Cusp Modelmentioning

confidence: 99%

“…Teeth are 'built to last' [11]. Nevertheless, such cracks remain precursors to enamel spallation [24] and wholesale splitting [35] in high force mastication, so it is desirable that their incidence be kept to a minimum. Again, proper occlusal function is vital to avoidance of premature fractures.…”

Section: Multi-cusp Complexity Allows For Enhanced Food Manipulationmentioning

confidence: 99%

“…The basis of the tooth modelling has been outlined in earlier articles [35][36][37]39], and only essential elements are reproduced here. The tooth is considered to consist of an enamel shell with nominal uniform thickness d on a cylindrical base with net height H and base radius R bonded to a dentine interior, depicted in the insets of figure 3.…”

Section: Setting Up the Cusp Modelmentioning

confidence: 99%

“…Generally, these critical loads increase with tooth base radius and height and enamel thickness [36,37]. More recent expansion of modelling to molar teeth with a symmetrical four-cusp structure [35,39], although preliminary in its findings, paints the way to a more comprehensive understanding of cuspal complexity. In this study, we address how systematic addition of cusps to an occlusal tooth surface and variation in the height of any individual cusp may influence the structural integrity of postcanine teeth.…”

Section: Introductionmentioning

confidence: 99%

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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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