RADIOGRAPHIC INTERPROXIMAL ANGULATIONS - IMPLICATIONS FOR ROTATIONAL PANORAMIC RADIOGRAPHY

Axial radiographs were taken on 160 subjects at the screening clinic o f the Dental School, University of Texas Health Science Center at San Antonio. Intermeatal and midsagittal lines, together with coordinate a xes and polynomial curves that represent the average dental arch form, were overlaid on each radiograph. Coordinate references for interprox imal tangents at 3154 contacts along the average dental arch form were digitized and angulations between the arch form and midsagittal plane calculated. Interproximal angulations at the average arch form were f ound to vary greatly but the average fluctuated around 90 degrees over the length of the arch. Optimal beam angulations were shown to be con siderably different from central ray angulations of current panoramic machines, and although most machines demonstrated favorable interproxi mal beam angulation in the anterior region, discrepancy in the premola r region ranged from 15 degrees to over 40 degrees. Overall the OrthOr alix SD (Gendex Dental Systems, S.r.l., Monza, Italy) orthogonal proje ction and PM 2002 CC (Planmeca Inc. Helsinki, Finland) deviate least f rom optimal interproximal angulation over most of the dental arch. How ever, the Planmeca gives a better angulation in the canine/premolar re gion, whereas the OP5/10 (Palomex Instrumentarium Corp., Helsinki, Fin land) is comparable with the OrthOralix SD in the molar region.