During which stage of tooth development does gemination (attempted division of a single tooth bud) occur?

Gemination occurs during the proliferation stage of tooth development (cap stage), when a single tooth bud undergoes attempted division or invagination, resulting in a tooth that appears to have two crowns joined together with a single (or partially divided) root and root canal. The total tooth count is normal (one unit counted for what appears as two teeth joined together). This distinguishes it from fusion (union of two separate tooth buds, resulting in a reduced tooth count). Gemination is more common in primary dentition and typically affects anterior teeth. It results from abnormal proliferation and attempted division of the inner enamel epithelium.