Palatal rugae positional changes during orthodontic treatment of growing patients.

OBJECTIVES: To investigate the anteroposterior and vertical changes of the median rugae area, which is commonly used as dental model superimposition reference, relevant to its underlying skeletal structures. SETTINGS AND SAMPLE POPULATION: Retrospectively collected pre- and post-treatment cephalometric radiographs and 3D digital dental models of 24 orthodontic patients (age at treatment start: 12.26 +/- 0.83 years; assessment period: 2.13 +/- 0.68 years) were analysed. All had mild to moderate malocclusions that were treated non-extraction with full fixed appliances. MATERIAL AND METHODS: The incisive papilla and rugae points were placed on the dental models that were then registered to the cephalometric radiographs. Afterwards, the radiographs were superimposed on Sella, ANS-PNS, and through a maxillary structural method. The vertical and horizontal movements of the papilla and the rugae points, as well as of a central incisor, were measured (Viewbox 4 software). RESULTS: The incisive papilla and the three rugae points remained stable anteroposteriorly, but moved downwards in the vertical dimension (approximately 1-2 mm), in a similar manner (P > .05). However, the anteroposterior position of the papilla and the first rugae points were affected by changes in anterior tooth position and inclination (P < .05). CONCLUSION: Both the second and third rugae can be used as superimposition references for tooth movement assessment. The use of the papilla and the first rugae area is not recommended, because they are affected by tooth movement. The outcomes of a palatal superimposition are comparable to those of a maxillary skeletal superimposition in the anteroposterior, but not in the vertical dimension.