ABSTRACT
Objective To investigate the reliability of cast measurements by comparing Photoshop and conventional hand-held method. Methods Maxillary standard plaster models from 10 orthodontic cases with crowding were enrolled in this study. The space available and the space required of anterior region were measured by using Photoshop in the digital pictures or conventional method used by 5 observers respectively.The measurement results of the same sample among every observer were analyzed with ANOVA, and the difference between the 2 methods was calculated and paired t test was used to analyze the data. Results The repeatability of measurement results was not good when the space available was measured with conven-tional method by different observer( M1 ～ M5 ), and the measurement results of M1 were significantly different from that of M3 and M5 respectively( P ＜ 0.05 ). The repeatability of measurement results was relatively good when the space available was measured by using Photoshop, and the measurement results of M5 were significantly different from other observers ( P ＜ 0.05 ). The measurement results of space required measured by different observer were very close, and the reproducibility was excellent when they were measured by means of Photoshop or conventional methods. Conclusion There were no much difference between Photoshop and conventional method to measure the required space. Photoshop had significant advantage over conventional method when available sRace was measured.