Dentata is Latin for 'toothed', 'having teeth.'
It is most often used in the phrase Vagina dentata, coined by psychoanalyst Sigmund Freud. This phrase was introduced to a generation of geeks in Neal Stephenson's Snow Crash, where it referred to an anti-rape device.
It is also used in the term fascia dentata, a part of the of the hippocampal circuit in the human brain, and in a number of formal names for various toothy, serrated, and denticulate species.
In nearly every other case toothed structures are referred to as dentate, as in 'dentate leaves' or the 'dentate gyrus' (also part of the hippocampus).
The suffix -ata is the Latin feminine form of the masculine -ātus; however in modern English it is most common to use -ate for all adjectives of Latin origin; technically, the suffix -ata should only appear in written Latin. It is therefor appropriate in obscure medical terms, the writings of pompous 19th century geniuses, and formal biological taxonomies, but should not generally be used otherwise.
Dentata does however appear as the name of at least one band and in the phrase Data Dentata. This suggests that a new proto-word is circulating in the collective unconscious, although what the meaning of this new word may be is as of yet indeterminate.
Dentata and dentate are not common words; if you find yourself using them, you may wish to consider serrate/serrated, or simply toothed and toothy, in their place.