An oral negative-pressure therapy system includes a container and absorbent insert for the container. The container includes a baffle inside an interior of the container. A fluid passageway extends along the baffle for delivering fluid (e.g., a mixture of air and saliva) into the container. The absorbent insert for absorbing liquid (e.g., saliva) in the container may is over the baffle. At least one of the baffle and the absorbent insert is configured to maintain a fluid flow path between the baffle and the absorbent insert to maintain fluid communication between a fluid inlet and a fluid outlet of the container. The absorbent insert and/or the container may be designed and constructed to burst air bubbles in the aspirated liquid. In one or more embodiments, the absorbent insert is replaceable so that a spent absorbent insert can be replaced with a new, fresh absorbent insert.