The affix urac comes in the sense of 'having projecting teeth' after the word danta,
Thus दन्ता उन्नता अस्य सन्ति = दन्तुरः ॥ The words in the sutra are either in the nominative or the locative case, but have the force of ablative.
Why do we say when the meaning is that of 'projecting'? Observe दन्तवान् 'having teeth'.,