A Novel Method for the Assessment of Three-Dimensional Tooth Movement during Orthodontic Treatment

Abstract

Objective: To (1) evaluate the stability of palatal rugae as landmarks for superimposition of dental casts and (2) establish a three-dimensional superimposition method of maxillary dental casts for analyzing orthodontic tooth movement. Materials and Methods: The sample consisted of dental casts obtained from 10 patients treated with extraction of bilateral maxillary first premolars and placement of three palatal miniscrews as anchorage for retraction of the anterior teeth. Dental casts were measured by means of laser surface scanning system, and three-dimensional images were reconstructed. Serial dental casts were superimposed on the three miniscrews as registration landmarks (miniscrew-superimposition method), and the displacement of each palatal ruga point during the closure of extraction spaces was measured. Displacement of the central incisors was measured by the miniscrew-superimposition method and the proposed superimposition technique (ruga-palate-superimposition method). Correlation analysis and paired t-tests were performed to determine whether a significant difference existed between the measurements of the two superimposition methods. Results: The medial points of the third palatal rugae and the shape of the palatal vault were stable throughout the treatment. The displacement of the central incisors measured using the ruga-palate-superimposition method showed no significant difference with that measured using the miniscrew-superimposition method. Conclusion: The maxillary dental casts can be reliably superimposed on the medial points of the third palatal rugae and the palatal vault as reference landmarks. (Angle Orthod. 2009;79: 447-453.)

Accuracy and reliability of palatal superimposition of three-dimensional digital models

“…Many authors have investigated the use of the palatal rugae as reference points for measuring tooth movements on serial dental casts [3][4][5][6][7] and on 3D digital models. 21,23,24 In a study of changes occurring in 15 patients who underwent extraction of four premolars, Peavy and Kendrick 6 reported that the lateral ends of the rugae close to the teeth followed the teeth in the sagittal plane, while the so-called O point on the midsagittal plane was least affected. Van der Linden 7 evaluated changes in rugae and interrugal dimensions in 65 normally growing children (aged 6 to 16 years) and in six orthodontically treated patients.…”

“…The orthodontic miniscrew may serve as an alternative reference landmark, but only in a limited number of cases. 22,23,25 Jang et al 23 evaluated the stability of palatal rugae using digital models superimposed on three miniscrews as registration landmarks and concluded that the medial points of the third palatal rugae and the shape of the palatal vault were stable throughout orthodontic treatment with premolar extraction.…”

“…10,11 Numerous studies have shown that 3D digital models can be used for model analysis and diagnosis, 10,[12][13][14][15][16] treatment planning, 8,17 design and manufacture of orthodontic appliances, [18][19][20] and evaluation of tooth movement. [21][22][23][24] To date, however, studies of the reliability of computed superimposition of 3D digital models to assess the outcomes of orthodontic treatments have been limited. 22,23 Our previous publication suggests that 3D digital model superimposition using the palatal surface as a reference is as reliable as cephalometric superimposition for assessing orthodontic tooth movement in maxillary premolar extraction cases.…”

“…[21][22][23][24] To date, however, studies of the reliability of computed superimposition of 3D digital models to assess the outcomes of orthodontic treatments have been limited. 22,23 Our previous publication suggests that 3D digital model superimposition using the palatal surface as a reference is as reliable as cephalometric superimposition for assessing orthodontic tooth movement in maxillary premolar extraction cases. 22 Nevertheless, it remains to be investigated how accurate digital superimposition techniques are for the quantification of tooth movements.…”

An In Vivo 3D Micro-CT Evaluation of Tooth Movement After the Application of Different Force Magnitudes in Rat Molar

“…The superimposing method has been previously described. 21 The superimpositions were performed within the same rat's material.…”