In brief, the isolated incisor pulp or germ with dental epithelium and surrounding dental follicle were placed in 4mg/ml Dispase and 3mg/ml Collagenase I on a thermomixer at 37 °C for 15 to 30min depending on the stage of the sample to release cells from the tissue. All our samples had more than 85% viable cells. For E13.5, E14.5, E15.5, E16.5, E18.5 and P56 wild-type mice incisors, libraries were prepared using SeekOne Digital Droplet Single-Cell 3′ library preparation kit (SeekGene). For Smoc1/2 DKO and wild-type control incisors, libraries were prepared using Single Cell 3′ Library Kit v2 (10X Genomics).