Purpose: In implant dentistry, the level of bone attachment is normally assessed by clinical and radiologic parameters. In the literature, however, the accuracy of these measurements has been a source of controversy. The purpose of this study was to assess the reliability of attachment measurements in the beagle dog model. Materials and Methods: In 6 beagle dogs, a total of 60 implants were placed. Bony defects resulting from plaque accumulation were treated surgically. All defects were evaluated at the time of surgery (T3) and 4 months later (T4). Evaluation included standardized measurements on radiographs, pressure-forced implant probing, and histometry. Furthermore, both conventional and digital radiographic techniques were used. Results: Both radiographic techniques showed very similar results at T3 and T4. At time T4, pressure-forced probing revealed statistically significantly different values than those obtained with radiography and histometry. When radiographic and histometric measurements were compared, no significant differences were found at either time T3 or time T4. Discussion: In this study, histometry showed better accordance with radiography than with pressure-forced probing. These results support the hypothesis that peri-implant attachment should be evaluated with a combination of both clinical and radiologic parameters. Conclusion: The exclusive use of radiography cannot be recommended for the measurement of peri-implant attachment.