Department;
of;
Pedodontics,;
School;
of;
Stomatology,;
Fourth;
Military;
Medical;
University,;
Xi'an,;
China;
Department;
of;
Oral;
Histology;
and;
Pathology,;
School;
of;
Stomatology,;
Fourth;
Military;
Medical;
University,;
Xi'an,;
China;
Research;
and;
Development;
Center;
for;
Tissue;
Engineering,;
Fourth;
Military;
Medical;
University,;
Xi'an,;
China;