EPIX: an interactive computer application program for cross-sectional epidemiological, periodontal investigations from X-ray films.

This article introduces the interactive computer application program EPIX and the associated personal computer/digitizer system. The system is used to measure marginal alveolar bone height and to record angular alveolar bone defects, defective margins of dental restorations and dental calculus from 5 X-magnified periapical radiographs in cross-sectional epidemiological investigations. The 134-kBytes compiled BASIC program provides 17 menu options. A complete recording of interproximal tooth surfaces takes on average 20 minutes per subject. Data from 200 subjects can be stored on one 5.25" floppy disk. EPIX transforms data files into text files to enable transfer to main-frame computer for statistical analyses. Data displays on VDU or paper are available. Routines for data location and processing, file processing and visual display of an operator's manual provide additional facilities. EPIX has been used to process an epidemiological material of 912 subjects and has proved to be useful.