The aims of this study were to review the literature on palatal rugae and their classification, and assess the pattern, shape, and average size in the medial-lateral direction of the first three anterior rugae of each side. In addition, we studied the factors influencing its size, with subsequent comparison of the results between gender, using digital models. This was a quantitative and qualitative study where 33 digitalized models of growing children (19 boys and 14 girls) from a previous research were evaluated. The palatal rugae were classified according to their shape and measurements were performed from the most medial point to the most lateral point of each of the first three anterior rugae on both sides using the OrthoAnalyser software (3 Shape). The most common palatal ruga shape was sinuous, followed by angle, curve, and straight, which together added up to over 90% (182 of 197) of the rugae shapes. As for the position, the most frequent in the first ruga (R1) was angle; whereas the sinuous shape predominated in the second (R2) and third (R3) rugae.The factors that influenced the sizes of the rugae include shape, number, and gender of the patients. The side of the rugae did not exert significant influence on its size. Palatal rugae did not exhibit a size pattern according to their shape and number. It is necessary to assess each patient individually in order to identify the variation regarding the shape and size of a particular palatal ruga.

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Background: The aim of this study was to evaluate linear measurements in digital models, scanned at different angulations, in order to compare four methods of superimposing digital models. Methods: Dental models obtained from the database of the School of Health and Life Sciences of the Pontifical Catholic University of Rio Grande do Sul (PUCRS) were scanned three-dimensionally at different angulations (0˚, 5˚, 10˚ and 15˚ in relation to the occlusal plane) and divided in four groups. The sample size was calculated and 43 dental models were used in this study. Linear measurements were obtained to assess the central and lateral portions of the 3D models, so that any possible distortion would be detected. Additionally, the digital models were superimposed using four approaches based on anatomical references: Methods 1 (three central landmarks), 2 (three lateral landmarks), 3 (surface + single landmark) and 4 (surface + three landmarks). Intraclass correlation coefficient was applied to evaluate the intra-observer reliability. Kruskal-Wallis was calculated to compare the groups according to the angulation during scanning, and Kappa to evaluate the agreement between superimposition methods. Results: No differences were found in models scanned at different angulations. Better superimposition correlation was observed between methods 3 and 4 those used techniques based on palatal surface associated to anatomical landmarks to superimpose. Conclusions: Linear measurements and superimpositions were not affected by the different angulations of the models during the scanning process. The most reliable superimposition methods were the ones using surface and landmarks.