Linear measurements are used on radiographs for various purposes, such as measuring lengths in endodontics, analysing bone loss in periodontal disease, and making age determinations in forensic dentistry. The purpose of this study was to analyse the accuracy of periapical radiographs for the measurement of the contact point to the crest of the bone compared to the actual measurements of a dried skull. A dried skull had lead squares measuring 1 × 1 mm attached to the contact point and the bone crest. Each site was radiographed using a parallel technique with a Rinn holder. The radiographs were taken perpendicular to the tooth and repeated at 10° and 20° horizontal angulations. The results showed that variation in the angle of the radiograph had a significant effect on the resulting measurements, F(1.7, 26.9) = 218.265, p < 0.001. The results from this study indicate that when measuring the contact point to the crest of the bone, a shift of 20° from the perpendicular of the tooth has a significant effect on the radiograph measurement and the actual measurement of the contact point to the crest of the bone on the actual skull.
Mahasneh et al. (Fri,) studied this question.