title: Reliability of a paralleling instrument for dental radiographs.
abstract: The reliability of a paralleling instrument for dental radiographs was retrospectively evaluated in the course of a 6-month clinical study. The angular variation between successive exposures was precisely quantified. Ninety-one percent of the angular variations were below a 1.4 degree threshold, but some paired images were found unsuitable for quantitative analysis. A mathematic procedure to assess the global angular projection error of any similar coupled x-ray cone-film holder device is proposed. This mathematic procedure should be routinely used to check superimposability of serial radiographs before density quantification or subtraction.
mesh_terms: D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D005069:Evaluation Studies as Topic; D005500:Follow-Up Studies; D006801:Humans; D008433:Mathematics; D011856:Radiographic Image Enhancement / Q000295:instrumentation*; D011861:Radiography, Dental / Q000295:instrumentation*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013382:Subtraction Technique
chemical_list: D015921:Dental Implants