Standardized and individualized vertical bitewing radiographs for a digital x-ray system

Abstract

Intraoral radiographs are important tools for diagnosing, monitoring and evaluating the treatment of infrabony lesions. However, different beam angulations between exposures may give a wrong interpretation when evaluating them. A technique that is useful for monitoring bone loss and regeneration is the use of subtraction radiography. This technique is also very sensitive for changes in projection geometry, thus highly standardized radiographs are required. Previous attempts have been made to standardize and individualize vertical bitewing holders in conventional radiographs by Duckworth et al. (1983). The aim of the present study was to develop a similar system for digital radiographs that can be used on a routine basis with minimal effort in the clinic in the case of infrabony and furcational lesions. The radiographs were also tested for the subtraction technique. For this study, vertical bitewings with an aiming device were employed. Wire markers were incorporated into the holders to enable measurements of angular variations and an occlusal index was used for individualization. The radiographs were taken on phantom heads. In total, 2 sets of measurements on 36 exposures were compared. Radiographs with a difference in projection geometry within 2 degrees were found to be acceptable for using the subtraction technique. 58% of the comparisons lie within this limit, both horizontally and vertically. It was concluded that by knowing which distances correspond to which degrees, the technique can easily be used in a clinical setting.