For as astonishingly and either endearingly, hilariously, or enfuriatingly backwards they were, the people of Earth were surprisingly advanced in the area of oral hygiene, particuarly for such an otherwise-unsophisticated civilization.
To give an idea of their advancement: among the non-contact planets of the whole outer rim of the Galaxy---of which there are many---humans of Earth ranked first in overall dental hygiene, and had the second-highest concentration of toothpaste varieties per capita in the entire Galaxy. The only race with a higher concentration are the Dentrassi, the culinary legends who strongly believe in the highest quality of all flavor experiences, and who also believe that superior oral hygiene leads to better flavor judgement.
Aside from its improbably plural location, part of the reason for such astounding advancement is that humans reached the civilized milestone of increased sugar intake rather early in their development. As all races do after reaching this point, they noticed the negative dental impact, and began developing accordingly. The strange thing that happened, however, is that this development never leveled off as with most other races. Some races either find a balance, or, as is more usually the case, become disillusioned with the futility of dental hygiene and give up on it altogether. Some of the more self-depricating races in the eastern mid-galactic bulge actually celebrate this resignation, holding Dedential Celebrations as a mildly amusing and unfortunate rite of passage.
The human race showed no signs of such resignation; indeed, at the time of the Earth's destruction, humans were actually slated to surpass the Dentrassi in the next two generations in dental quality. Had this occurred, and had interstellar contact been established, the planet could have made a small fortune in oral procedures, and could have led something of a renaissance in dental hygiene.