Effect of Horizontal Angulation on Radiographic Measurement of the Contact Point–Alveolar Bone Crest Distance: An In Vitro Study

Linear measurements are used on radiographs for various purposes, such as measuring lengths in endodontics, analysing bone loss in perio-dontal disease and making age determinations in forensic dentistry. The purpose of this study was to analyse the accuracy of periapical radio-graphs 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 x 1mm 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 perpendicularly 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 meas-urement of the contact point to the crest of the bone on the actual skull.