Microparticle slip:

i) Mineral microspheres are both organically and aqueously encapsulated.

ii) At a crucial point of bone water content, hydrogen bonding between particles is powerful enough to support daily stresses (above/below this, bonds are weaker and particles more mobile).

iii) Cyclic stress disrupts hydrogen bonds causing particle slip (i.e. microdamage type I).

Crystal fracture:

i) Enamel mineral is exposed and crystalline.

ii) There is no water and little hydrogen bonding.

iii) When stressed, it displays crystal fracture along lattice planes (i.e. microdamage type II).

iv) There are circumstances when bone may behave like enamel by inherent fault or design (e.g. fluorosis).