出典:Wiktionary
inter- + second as a surface analysis that succeeds by way of syntactic reanalysis, although the escape from nonword status is recent and prescriptively arguable; see usage notes.
intersecond (not comparable)
The adjectives interfirst and intersecond in reference to teeth (premolars または molars) are rarely used nonstandard forms born of editorial errors. They arise from compound constructions such as /inter + first molar + distance/ (the distance between the first molars in a given dental arch) that undergo a copyeditorial error in which a general rule to remove unnecessary hyphens from prefixes that don't need them is misapplied to a term where multiple hyphens or an en dash should have been used: either inter-first-molar distance (two hyphens) or inter–first molar distance (one en dash).