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The aim of this study was to identify the potential projection errors of lateral, postero-anterior (PA) and submentovertex (SMV) cephalometric radiographs due to head rotation in the vertical z-axis. For this investigation, a complete human dry skull of an adult was used. The skull was rotated from 0 to +/-14 degrees at 2 degree intervals. A vertical axis, the z-axis, was used as the rotational axis to expose 15 lateral and 15 PA cephalometric radiographs. The skull was tilted on each side, again at 2 degree intervals, to expose the 15 SMV films. A series of linear and angular measurements was carried out on all cephalograms. The results revealed that horizontal linear and angular measurements between the horizontal planes on lateral cephalograms were subject to changes from 16.1 to 44.7 per cent with a 14 degree rotation of the head position. For PA cephalograms, again horizontal linear measurements, particularly mandibular length, were subject to a projection error of up to 34.9 per cent with head rotation. On the other hand, projection errors were within the 3-4 per cent limit for SMV radiography. The findings indicate that: (1) linear measurements and the measurement of angles between the horizontal planes are likely to be affected by head rotation in lateral cephalograms, (2) angular measurements demonstrate smaller variations with changing rotation of the head in PA cephalograms, (3) SMV radiographs are less vulnerable to head rotation. Vertical linear measurements of lateral cephalograms and angular measurements of PA radiographs are more reliable in minimizing the projection errors associated with head rotation.

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Orthodontic forced eruption may be a suitable approach without risking the esthetic appearance in tooth fracture below the gingival attachment or alveolar bone crest. Extrusion of such teeth allows elevating the fracture line above the epithelial attachment and so the proper finishing margins can be prepared. Restoration after orthodontic eruption may present a more conservative treatment choice in young patients compared with the prosthetic restoration after extraction. This case describes a multidisciplinary approach using the orthodontic forced eruption facilitating the composite restoration of a fractured upper permanent central incisor.