Talaat S, et al. – Using Ortho Mechanics Sequential Analyzer (OMSA), the aim of this study was to assess the validity and reliability of three–dimensional (3D) landmark–based palatal superimposition of digital dental models. The outcomes suggested that OMSA offers a valid and reliable tool for 3D landmark–based digital dental models superimposition using 3 points marked along the midpalatal raphe as a reference.