"Probing depths" refers to measuring the depth of a pocket formed between the gum and tooth during a dental check-up. It helps dentists assess the health of the gums and identify any signs of gum disease or inflammation. Full definition
A good and useful review probes the depths of a book's message to reveal the quality of its themes, attitudes and ethics. (winningedits.com)
Normal probe depths are 1 - 2 mm in the dog and less than 1 mm in the cat. (thepetdentist.com)
A glaciologist develops a lightweight method for probing the depths of Greenland's ice sheet to answer a crucial question: How fast is it melting? (theconversation.com)