Comparison of two digital maxillary superimposition methods for evaluation of orthodontic tooth movement
Kanza Khan, Sohrab Shaheed, Nasir MushtaqObjectives:
A digital model can be used to evaluate periodic tooth movement during treatment with fixed orthodontic appliances to obtain functional and esthetic outcomes, avoid unnecessary movements, and to decrease the treatment time, expenses, and side effects. Assessment of orthodontic tooth movement depends on the presence of a stable structure, this study aimed to compare two digital superimposition methods, i.e., the 3 rd rugae method versus the anterior palatal vault method, to suggest a stable reference area and to find a simple, efficient, and precise way to evaluate orthodontic tooth movement.
Material and Methods:
Maxillary digital scans of 93 patients were obtained at the beginning of treatment (T0), and at 6 months (T1) after the start of active treatment. To assess the tooth movement from T0 to T1, following reference areas were selected on the T0 model: (a) area A: a small area of the palate including the medial two-thirds of the third rugae and the area 5 mm dorsal to them (b) area B: almost the whole palate including all rugae delineated by a line 5 mm from all the gingival margins and spreading posteriorly back until the middle of the 1st permanent molar. Superimposition was done in two steps to get more precise results, which allowed calculation of movement in all three planes of space.
Results:
Paired t -tests revealed that there were no statistically significant differences in the means of linear tooth movements and rotation of both the superimposition methods. The Pearson correlation coefficients of both methods revealed that the r values of all the variables were very high. Bland-Altman plots revealed no significant differences between the two methods for both the linear and rotational measurements
Conclusion:
Both methods showed comparable accuracy and reliability for three-dimensional digital maxillary superimposition and represent reliable reference areas.