Denisovan hemimandible from Xiahe has lower second molar with 3 roots dated 160,000 ka. Third root trait occurs in <3.5% non-Asians but up to 40% Asians and New World groups. Frequencies for lower second molars (LM2) are rare even in Asians at 1.4% Chinese and 1.9% Aleuts. Bailey et al cited frequencies for lower first molars (LM1) not LM2. Xiahe accessory root is mesiolingual and larger than one-third distal root size unlike distolingual Asian 3RLM. Penghu fossil shows similar robust extra root between mesial and distal but differs from modern Asian supernumerary. Bifurcated mesial roots exist in modern populations but Xiahe version not homologous to Asian 3RLM. Feature provides no evidence of Denisovan introgression into Asians. Phenotypic signature of hybridization unclear as admixture often causes innovation not intermediates. Higher archaic feature expression may indicate primitive retention not introgression. Isolated dental features should not be overinterpreted for admixture.