Precision in Facial Measurements: Comparative Analysis Between a Digital 3D Scanner and an Analog Instrument

Background: Accurate facial proportion analysis is essential for therapeutic planning in dentistry. This study aimed to evaluate the Planmeca ProFace 3D scanner's accuracy by comparing its digital measurements to analog caliper measurements. Methods: A comparative cross-sectional study included seven patients. Fourteen standardized facial landmarks were measured digitally and with an analog caliper. Distances were grouped as small (<= 6.5 cm, Group A) or large (>6.5 cm, Group B). Paired t-tests, Cronbach's Alpha, and Bland-Altman analysis assessed differences, reliability, and agreement. Results: The results showed a statistically significant difference between the two methods of measurements in group A (p = 0.016) and high statistical significance was obtained in group B (p = 0.001). Cronbach's Alpha showed high reliability for Group A (alpha = 0.982) but low for Group B (alpha = 0.270). The mean difference between the caliper and software measurements was 0.24 +/- 0.9 SD (min 0.16 max 2.92) in group A and 0.71 +/- 2.8 SD (min 0.02 max 4.17). Bland-Altman analysis revealed a consistent positive proportional bias, with differences increasing for larger measurements. Conclusions: Facial point measurements by the means of digital scanning technique show measurements overlapping with analog technique for measurements less than or equal to 6.5 cm, with significant deviation for points with a distance greater than 6.5 cm. A hybrid approach or compensatory strategies are needed to ensure clinical precision.