In this 2019 video, Dentist Dr. Gerry Curatola, rejuv-health.com, and Dr. Daniel Pompa, a Chiropractor, drpompa.com, discuss dental cavitations, and at timestamp 38:40, they show a photo of what a dental cavitation looks like when the dentist first opens up that area of the mouth (it is a hole in the bone that is filled with decay), https://www.youtube.com/watch?v=MUDMXhjuzBU.
In this 2019 video, Dentist Dr. Jorgensen walks you through the process of dental cavitation surgery, and she mentions at timestamp 1 minute that the contents of a dental cavitation appears oily due to fatty necrosis, https://www.youtube.com/watch?v=sdi9gLP2D00.