Telling a radiographic artifact from real pathology is a reading skill, and it is less settled than the tests for it suggest. Some of the radiolucencies you will be asked to call are not lesions at all — they are the beam, the geometry of the tooth, or your own visual system.
Dental school teaches the facts. It rarely gives students the repetitions that turn facts into pattern recognition. Papilla is built around that gap: real patient radiographs, one call at a time, with a licensed dentist's reasoning waiting on the other side.
Learning to read dental radiographs means building two things that can be measured separately: where your eyes go, and what you make of what they land on.
Bitewing and periapical radiographs answer different questions, and current ADA/AAOMR recommendations say the choice between them should be guided by clinical judgment, the lesion's location and anatomical factors rather than by a fixed rule.
You'll be told to read every radiograph the same way, in a set order. That advice isn't wrong, but the order your eyes travel is not what separates a strong reader from a struggling one. Two habits carry most of the load, and neither depends on which route you pick.
Two separate things go wrong at the cervical region of a posterior tooth, and most teaching names only one. The first is in the radiograph: there really is less tooth there to absorb the beam, so that strip really is darker.