[Effects of diverse influencing factors in clinical dental photography on depth-of-field sharpness and distortion: a comparative study].

Abstract

Objective: To evaluate the effects of different combinations of digital single-lens reflex cameras and macro lenses, aperture settings, and focusing points on depth-of-field sharpness and image distortion in dental clinical photography, and to provide evidence-based guidance for standardizing dental clinical photography. Methods: Full-frame and advanced photo system type-C APS-C digital single-lens reflex cameras were paired with 105 mm and 60 mm macro lenses. Photography was performed under eight preset aperture values (F16, F18, F20, F22, F25, F29, F32, and F36) on a standard oral model, focusing separately on three points simulating the central incisor, canine, and first molar. Five attending physicians, who had completed standardized training in dental esthetic clinical photography and calibration training (with over 5 years of dental clinical photography experience), evaluated the depth-of-field sharpness of the photographs using a double-blind method. Image distortion was assessed by measuring the width-to-length ratio of the central incisor. Results: Photographs taken with the APS-C digital single-lens reflex camera combined with the 105 mm macro lens showed significantly higher depth-of-field sharpness scores (2.756±0.357) compared to other camera-lens combinations (P<0.05). Photographs taken at aperture settings of F25, F29, F32, and F36 demonstrated significantly higher depth-of-field sharpness scores than those taken at F16, F18, F20, and F22 (P<0.05). Images focused on the simulated canine achieved the highest depth-of-field sharpness scores, followed by the central incisor, with the first molar showing the lowest scores (P<0.05). Main effect and interaction effect tests revealed that camera-lens combinations significantly affected image distortion (F=2.79, P=0.042), while focusing points and aperture settings showed no significant effect on image distortion (F=0.40, P=0.671; F=1.27, P=0.270). Conclusion: Based on experimental data analysis, using an APS-C digital single-lens reflex camera with a 105 mm macro lens, setting the aperture value between F25 and F36, and focusing on the canine can ensure sufficient depth-of-field sharpness while avoiding image distortion, thereby achieving optimal results in dental clinical photography.