Tooth structure can be regenerated by implanting dissociated tooth cells seeded onto a scaffold, and all structures in the tooth can be observed by this technique. However, a complete tooth cannot be regenerated by this technique, and several issues arise. For instance, the tooth structures vary widely in shape, and none shows normal tooth morphology. PURPOSE: This study was designed to evaluate whether tissue-engineered tooth morphology can be regulated by a new way of seeding cells onto the scaffold. METHODS: Enamel organ and dental mesenchyme from porcine third lower molars were enzymatically separated. Each tissue was further dissociated into single cells. The isolated mesenchymal cells were first seeded only in the scaffold, and the isolated epithelial cells were seeded on top of the mesenchymal cells in the scaffold. Both cells were in direct contact with each other on the scaffold. Scaffolds were then cultured so that cell proliferation and ALP activity could be evaluated in vitro. We performed an in vivo analysis by implanting the constructs into the omentum of immunocompromised rats and evaluating tooth production for up to 20 wks. RESULTS: ALP activity from the experimental group was higher than that of the control group in an in vitro study. The combination of the mesenchymal cells with epithelial cells on the scaffold exhibited a tooth structure and morphology similar to those of a natural tooth. Interestingly, one tooth structure could be formed in one scaffold. However, the control group exhibited no tooth structures. CONCLUSION: These results suggest that cell-cell direct contact requires a producing tooth, and the regulation of the cell-cell contacts plays a key role in controlling the morphology. The way of seeding cells used in this study could be useful to regulate the morphology of tissue-engineered teeth. However, a complete tooth was still not reproduced this way.