OBJECTIVETo study the influence of moisture on the mechanical behavior of human dentin and fracture mechanism with crack extension in dentin.

METHODSA loading system that was suitable for biological materials was presented in this paper. With the help of digital image correlation (DIC), the surface deformation of wet samples was analyzed. Miniature compact tensile specimens were made from molars extracted from human beings. The fracture mechanism of human dentin was studied with compact tension (CT).

RESULTSHydrated dentin behaved like visco-elastic material while dehydrated dentin became brittle. The bridged tissue behind the crack tip and the blunting effect at the crack tip resisted the extension of crack in dentin.

CONCLUSIONSHydration plays an important role in mechanical properties of dentin. Dentin tissue has the ability to resist within extension of crack, however this ability decreases with aging.