Cov txiaj ntsig tau tshwm sim feem ntau yog cov khoom kawg, thiab tsis tas yuav tsum ua lwm yam ua ntej kev teeb tsa lossis siv ua khoom kawg.
Ntau cov ntsiab lus, xws li protrusions, tav, thiab xov, tuaj yeem tsim hauv ib qib ntawm kev txhaj tshuaj molding.