2 | Three lateral landmarks | Occlusal tip of the right canine, buccal cusp of the left first premolar and mesio-buccal cusp of the right first permanent molar |
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3 | Surface + one landmark | The medial point of the right third ruga and the surface selected on the palate |
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4 | Surface + three landmarks | The medial point of the right second palatal ruga, the medial points of the right and left third rugae, and the surface selected on the palate |
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