Radiographs of dental implants in the edentulous mandible, which are suitable for evaluation studies, are difficult to obtain. This article describes the development of an aiming device for intraoral radiography of the crestal bone around the neck of dental implants. Error analysis of serial radiographs indicated only small deviations in reproducibility. Subsequently three methods of measurements of marginal bone level around the neck of dental implants are described, measurements with: 1. a computerized image analysis system, 2. a magnifying glass, and 3. a digital sliding gauge. The intra- and interobserver error analysis showed that determining the precise bone height on the image is responsible for a large standard deviation for each me...