There can be other explanations too.įor example, it may be that the tooth’s original pre-treatment lesion simply hasn’t fully healed yet. more dense cortical bone) that exists in the affected area.īut discovering a dark spot on an x-ray doesn’t necessarily mean that a problem exists. When will a radiolucency (bone changes) show on an x-ray?īefore a developing lesion will show up as a dark spot on a radiograph, the bone in the affected area must have finally reached a point where at minimum around 7% of its mineral content has been lost, and possibly as much as 30 to 50%, depending on the type of bone (cancellous vs. As a result, that portion of the picture appears darkened (referred to as radiolucent areas). In areas having low-density, the x-ray beam passes through the structure easily, thus exposing/triggering the x-ray film/sensor.That’s because the density of the object blocks the x-rays, and as a result that part of the x-ray film/sensor is shielded and remains unexposed, thus the object appears white or light in color. Areas having high-density show as white regions (referred to as radiopacities).Possibly only somewhere on the order of 55 to 65% of root canal cases initiated because of pulpitis (a state where the tooth’s nerve tissue is still alive but inflamed) show evidence of a periapical radiolucency at the time that their diagnosis for endodontic therapy is made.Īs alluded to above, a radiolucency shows up on an x-ray because the bone in that region is less dense (it contains less mineral content, or else there is an actual void in the bone tissue in that area). Why isn’t a radiolucency always evident on an x-ray of a tooth that needs root canal therapy? Additional details about radiolucencies of endodontic origin. The formal classification of the actual lesion (radiolucency) that forms might be: apical periodontitis, apical granuloma, acute apical abscess or radicular cyst.
In essence, the formation of an endodontic periapical radiolucency is evidence of the person’s body creating a line of defense against the spread of bacteria and infection byproducts from within its associated tooth.And as this space forms, it fills with immune cells whose purpose is to defend against the irritants leaking from the tooth. An aspect of this response is one where bone tissue is sacrificed from immediately around the point of exit from the tooth (hence the formation of the dark spot that’s seen on the x-ray).As byproducts from the infection leak out of the tooth (via the opening at the tip of the root where the tooth’s nerve used to enter), they trigger an inflammatory response in the surrounding tissues.It’s a sign of infection located in the nerve space inside the tooth.