A  

The primary maxillary (upper) first molar has a small, squat crown with only two well-developed cusps and an occlusal outline that is very similar to a permanent premolar, leading many authors to describe it as “a premolar-type crown on molar roots.” In contrast, the primary second molars mimic permanent first molars, and the mandibular first molar has a unique shape that does not resemble any other tooth. Hence, the upper first primary molar is the deciduous tooth that most closely resembles a premolar [Diéguez-Pérez 2022 PMID 35954635; Ramakrishnan 2020 PMID 34938003].