Delayed implants in the anterior maxilla with the IMZ-implant system: a radiographical evaluation

One hundred and seventy-three IMZ-implants in 81 patients, placed in the anterior region of the maxilla, were evaluated radiographically by two observers. Radiographs were evaluated at three intervals, namely at the time of implant placement, the time of prosthetic restoration and at the latest available radiograph, on average 2 1/2 years after implant placement. In this study marginal bone height and the type of radiolucency adjacent to the implant were determined. Both observers were able to classify the marginal bone height (mesial and distal) and the distinctive type of resorptive defects to an acceptable level of agreement, with Cohen's kappa ranging between 0.48 and 0.69. It was found that, at the most recent visit to the clinic, angular-shaped resorptive defects are found mesially and/or distally of the implants at approximately 25% of the implants. At this stage 20.7% of the mesial implant sites and 27.9% of the distal implant sites show marginal bone heights less than three-quarters of the implant length. These findings do not fully underscore and sometimes even contradict the clinical observations which were considered highly satisfactory.