Cox C F, Heys D R, Gibbons P K, Avery J K, Heys R J
J Dent Res. 1980 Feb;59(2):109-15. doi: 10.1177/00220345800590020101.
This study showed a statistically significant difference between the microhardness of reparative and primary dentin at both five-and eight-week intervals. Reparative dentin from occlusal trauma is harder than reparative dentin underlying a cavity preparation at the 99% level. No statistical difference was noted in the hardness of reparative dentin underlying different materials, but trends were observed.