BACKGROUND AND OBJECTIVE: The tooth root is one of the critical parts to 
maintain tooth function; however, the molecular mechanisms of root development 
remain unknown. We aimed to identify specific factors for root morphogenesis 
using a newly developed experimental system.
MATERIAL AND METHODS: Tentative cementoblasts and periodontal ligament cells 
from mouse mandibular molars were isolated using laser capture microdissection. 
More than 500 cementoblasts and periodontal ligament cells were separately 
captured. After RNA extraction and amplification, mRNA expression in isolated 
cementoblasts was compared with that of periodontal ligament cells by cDNA 
microarray analysis. Then, putative cementoblast-specific genes were subjected 
to in situ hybridization analysis to confirm the results in mouse mandible.
RESULTS: Approximately 2000 genes were differentially expressed between these 
tissues. Among those genes, zinc finger helicase (ZFH), also termed 
chromodomain-helicase-DNA-binding protein 3 (Chd3), was one of the highly 
expressed transcripts in tentative cementoblasts. In situ hybridization revealed 
that ZFH/Chd3 was strongly expressed in Hertwig's epithelial root sheath rather 
than in cementum. Moreover, its expression disappeared when root formation was 
advanced in the first molar. In contrast, Chd3 was continuously expressed in 
dental epithelial cells of the cervical loop, in which root extension is never 
terminated.
CONCLUSION: These results suggest that ZFH/Chd3 might play an important role in 
tooth root development and subsequent cementogenesis.