D2 Biomaterials Lecture 8: Age Effects on Teeth

What dental issue is most prevalent in older patients?

Tooth fracture

What two levels are decreased in bones with aging?

1. Mineral content

2. Tissue density

What is the percentage of occurence in crown and root caries in patients exceeding 65 years?

65%

What is the thickness of the cuff of peritubular lumen that lines the tubule lumen?

0.5 - 1 μm

What is the matrix of collagen in intertubular dentin reinforced by?

Apatite

What results from the deposition of mineral within the lumen during aging?

Increase in peritubular dentin thickness

What percent of dentinal tubules can naturally become completely occluded with age?

50%

What level is decreased with the reduction in lumen diameter?

Dentin permeability

What is the issue with dehydrated dentin caused by dentin permeability?

Brittleness

What is the term for the energy required to induce failure?

Toughness

What is the flexural strength of young dentin?

140 MPa

What is the flexural strength of old dentin?

80 MPa

From ages 20 - 50, how much does the dentin strength decrease per decade?

20 MPa

What is the endurance strength of young dentin?

44 MPa

What is the endurance strength of old dentin?

22 MPa

What level is increased with crack extension on dentin?

Fracture resistance

How does crack resistance of dentin change with age?

Decreases

What causes the toughening of dentin with increased crack extension?

Bridging forces of collagen fibrils and unbroken ligaments

What effect of age decreases the toughening ability of dentin?

Less unbroken ligaments

What in obturation could cause vertical root fracture?

Excessive forces

What in lateral condensation could cause vertical root fracture?

Wedging of spreaders

What in post cementation could cause vertical root fracture?

Excessive pressure

How can instrumentation cause vertical root fracture?

Decrease in dentin thickness

Which teeth have more vertical root fracture risk in patients age 40+?

Posterior teeth

How can dentin that becomes transparent with age be described?

Sclerotic

What makes fatigue properties of dentin important?

Cyclic loading

How much does the stress intensity threshold decrease from young to old dentin?

25%