I had one yanked today, so I thought I’d post about the Indo-European forms, which mostly all come from the same root and which beautifully illustrate all sorts of sound changes; this is the sort of thing that got me interested in historical linguistics. The Germanic forms — Old English tóþ, Old Saxon tand, Low German tan, Dutch tand, Old High German zan(a) (German Zahn), and Old Norse tǫnn (Swedish, Danish tand, Norwegian tonn) — all come from a reconstructed *tanþuz (Gothic Gothic tunþus has a different vowel that must come from the zero grade); French dent, Italian dente, Spanish diente, and Romanian dinte all come from Latin dent– (nominative dens); Greek odont– (nominative odous) shows the o-grade and an initial laryngeal; and all these, plus Sanskrit dant-, Welsh dant, Old Irish dét (i.e., /de:d/), Lithuanian dantìs, and Armenian atamn, come from a Proto-Indo-European root reconstructed as *dent-. The AHD IE Appendix lays it out by root grade, beginning with the suggestion that it was originally a participle:
Tooth. Originally *h1d-ent‑, “biting,” present participle of ed– in the earlier meaning “to bite.”
1. O-grade form *dont‑. tooth, from Old English tōth, tooth, from Germanic *tanthuz.
2. Zero-grade form *dn̥t‑. tusk, from Old English tūsc, tūx, canine tooth, from Germanic *tunth-sk‑.
3. Full-grade form *dent‑. dental, […] from Latin dēns (stem dent‑), tooth.
4. O-grade variant form *ədont‑, ultimately becoming odont‑ in Greek –odon, […] from Greek odōn, odous, tooth.
[In Pokorny ed‑ 287.]
The Slavic words (Russian зуб [Vasmer], Polish ząb, etc., all
from related to OCS зѫбъ), like Latvian zùobs and Albanian dhëmb, come from a different root, *gembh- ‘tooth, nail,’ which gives English comb among others, and Irish has fiacail, which is just weird.