Liverdos K, Tsamis Ch, Parissis N.K.
Stoma 2005; 33: 97-106.
Abstract:
In order to achieve high credibility in the appearance of X-rayed objects with intraoral periapical radiographs, the X-ray film should be placed near and parallel to the examined area with the central ray aiming the film perpendicularly. The right angle or paralleling technique is based on these basic rules. As far as the fidelity of the appearance of the radiographed object is concerned, this technique overcomes the standard bisecting angle technique. To apply this technique a 30 or 40-centimeter-long collimator is needed. The great majority of dental X-ray units are equipped with a 20-centimeter collimator. With this kind of collimator, this technique produces a small percentage of magnification due to the divergence of the X-rays. Intraoral radiographs constitute a useful tool in the hands of the dentist, who uses implants, and they constitute an accurate imaging technique. Radiographs are used before, during and after the different surgical phases.
PURPOSE: In this research, the distortion percentage of the paralleling technique with the use of a 20-centimeter collimator was checked.
MATERIALS AND METHOD: From the files of the Department of Oral Surgery, Surgical Implantology and Radiology of AUTH dental school, 89 intraoral radiographs were gathered, of implants (Frialit Dentsply Friadent and 3i Implant Innovations INC) which were placed in patients of our department. The radiographs were digitized and the radiographic lengths of the images of the implants were measured. The measurements were compared with the actual size of the inserted implants. The results were analyzed and the mean value of the radiographic distortion of the implant images in the different areas of the dental arches was calculated.
RESULTS-CONCLUSIONS: a) The paralleling technique with the use of a 20-centimeter collimator is a reliable enough technique in implantology, which does not produce distortion greater than 10%, b) the mean value of the radiographic distortion of the implant images was found to be not bigger than 7% and that in the area of the posterior mandibular teeth, the distortion was very small to zero. It can be said that provided the technique is applied correctly, it is safe to take under consideration, a distortion percentage of 10% during the interpretation of the radiograph.
