Photogrammetric angular measurements as a diagnostic tool for orthodontic treatment planning

Abstract

Objectives: The aim of the study was to compare and correlate angular measurements of soft-tissue profile between cephalogram and photograph and to identify gender difference. Materials and Methods: Sample size consisted of 100 lateral cephalograms and 100 profile photographs of 100 Indian Bengali population aged 18– 25 years (50 males and 50 females; mean age = 21.28 years). All records were taken in natural head position, centric occlusion, and lips in relaxed position. For evaluation of method reliability, intra-class correlation coefficients (ICCs) were calculated from repeated photographic measurements. Similarly, cephalometric and photographic measurements were compared for assessing Pearson correlation coefficients. Linear regression analyses were done for the variable with correlation coefficients >r = 0.7. Ten angular parameters were used for soft tissue analysis and t-test was used for comparison. Statistical analyses were done using the Statistical Package for the Social Sciences for Windows software version 21.0. Results: The reliability test for photographs was found satisfactory with most measurements showing ICCs ≥ 0.90 and highly significant correlations (P ≤ 0.001) with cephalometric measurements. The N’-Prn’-Pg’ angle was found most effective for female subjects (r2 = 0.82), the N’-Prn’/N’-Pg’ angle for male subjects (r2 = 0.89) and among total subjects, the N’-Prn’/N’-Pg’ angle (r2 = 0.88). Conclusion: Photographs may be used for soft tissue evaluation for diagnosis and treatment planning as an alternative to cephalometric soft-tissue analysis.