Either conventional or digital periapical radiographs are useful in evaluating interproximal bone levels (Figure 6). These radiographs should be compared to baseline radiographs obtained when the final restoration was placed. Radiographic comparison with baseline values is particularly useful. Subtraction programs are also available to further define radiographic changes. In the absence of such a program, however, radiographs taken perpendicular to the implant can show clear thread demarcation, useful for comparison.