There are 3 factors which affects the appearance of the nose: skin, cartilage and bones. You were not very specific in describing the location and appearance of the dent, so I'll discuss a little on all 3:
- Skin - scars from previous trauma, permanent wrinkle lines due to frequent nose rubbing from allergic rhinitis, or even acne scars can cause a dent or depression on the nose. Typically these kinds of dents can be reduced with lasers, resurfacing or scar revision surgeries.
- Cartilage - cartilage is found in the lower 2/3 of the nose. There are 2 pairs of upper and lower lateral cartilages, as well as the nasal septum that may be visible, especially if your skin is thin. Any defect/ contour deformity in these cartilages may show up through thin skin. You may not even have a history of trauma or injury. Treatment options include simple camouflage with fillers, or surgery to correct the cartilage deformity. The latter is particularly worth considering if they are causing you breathing problems as well.
- Bones - these are located in the upper 1/3 of the nose. Previous nasal fractures and trauma can cause the bones to be crooked or dented. Once again options to treat include fillers, or surgery to re position the bones in their correct position.
