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The European Journal of Orthodontics Advance Access originally published online on May 19, 2007
The European Journal of Orthodontics 2007 29(4):325-331; doi:10.1093/ejo/cjm019
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© The Author 2007. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org.

Analysis of tooth movement in extraction cases using three-dimensional reverse engineering technology

Bong Kuen Cha*, Jae Yong Lee*, Paul-Georg Jost-Brinkmann** and Noriaki Yoshida***

* Department of Orthodontics, College of Dentistry, Kangnung National University, Gangneung, South Korea
** Department of Orthodontics and Dentofacial Orthopedics, Centre for Dental and Craniofacial Sciences, Charité—Universitätsmedizin Berlin, Germany
*** Department of Orthodontics, College of Dentistry, Nagasaki National University, Japan

Address for correspondence Bong Kuen Cha, Department of Orthodontics, College of Dentistry, Kangnung National University, 120 Gangneung Daehangno, Gangneung city, Gangwon province, , 210-702, South Korea, E-mail: korth{at}kangnung.ac.kr


   Summary
Top
 Summary
Introduction
 Materials and methods
 Results
 Discussion
 Conclusion
 References
 
Despite inherent errors, cephalometric superimpositions are currently the most widely used means for assessing sagittal and vertical tooth movements. The purpose of this study was to compare three-dimensional (3D) digital model superimposition with cephalometric superimposition. The material was collected from initial and final maxillary casts and lateral cephalometric radiographs of 30 patients (6 males, 24 females, mean age 17.7 years) who underwent orthodontic treatment with extraction of permanent teeth. Each pair of cephalograms was traced and superimposed according to Ricketts’ four-step method.

3D scanning of the maxillary dental casts was performed using INUS dental scanning solution®, which consists of a 3D scanner, an autoscan system, and 3D reverse modelling software. The 3D superimposition was carried out using the surface-to-surface matching (best-fit method) function of the autoscan system. The antero-posterior movement of the maxillary first molar and central incisor was evaluated cephalometrically and on 3D digital models. To determine whether any difference existed between the two measuring techniques, paired t-tests and correlation analysis were undertaken.

The results revealed no statistical differences between the mean incisor and molar movements as assessed cephalometrically or by 3D model superimposition. These findings suggest that the 3D digital orthodontic model superimposition technique used in this study is clinically as reliable as cephalometric superimposition for assessing orthodontic tooth movements.


   Introduction
Top
 Summary
 Introduction
Materials and methods
 Results
 Discussion
 Conclusion
 References
 
The dental cast is the traditional three-dimensional (3D) patient record for measuring linear changes in the dental arch. However, it does not provide important information such as structural and volumetric changes in the palate or 3D measurements of orthodontic tooth movement.

Many studies have reported on the stability of the palatal rugae as reference points for pre- and post-treatment comparisons on stone casts (Peavy and Kendrick, 1967Go; van der Linden, 1978Go; Almeida et al., 1995Go; Hoggan and Sadowsky, 2001Go). However, views differ regarding the stability of the rugae as a reference for dental cast measurements, and their role as a reference for serial records of growth or treatment change is highly questionable. This is due to problems with measuring procedures, difficulties in establishing reference planes for superimposition of serial data, and inherent errors.

Superimposition of serial cephalograms has thus far been the most widely used method for measuring tooth movements after orthodontic treatment. However, its drawbacks include difficulties in evaluating 3D dental movement and identifying inherent landmarks. Further disadvantages are tracing errors, frequent radiation exposure, and high costs (Ghafari et al., 1998Go).

Since the introduction of CAD/CAM systems with various 3D scanning techniques, efforts have been directed towards developing modalities such as CEREC® for its clinical application in conservative dentistry (Mormann et al., 1987Go; Mehl and Hickel, 1999Go).

Until recently, in orthodontics, stone casts were the only way to accurately document malocclusions. However, digital alternatives have now become available in the form of 3D computerized models (Commer et al., 2000Go; Cha et al., 2002Go).

Another example for digital 3D data acquisition in orthodontics is the bending art system (BAS)® (Fischer-Brandies et al., 1997Go) for automated bending of orthodontic archwires, which is based on an intraoral data-acquisition method. The Invisalign system® is a new treatment modality that utilizes computer-based virtual orthodontic models to create a series of clear removable aesthetic appliances (Sachdeva, 2001Go).

In the area of orthodontic diagnosis, however, the technique has not been used in many studies other than simple model analysis, digitized data storage, and processing. Several ways of applying 3D reverse engineering technology for model analysis have been explored and it has been suggested that it could be a viable alternative to the conventional cephalometric technique for more accurate and convenient evaluation of orthodontic tooth movement (Cha et al., 2002Go).

The purpose of the present study was to test the hypothesis that the mean horizontal and vertical movements of the upper molars and incisors assessed by digital model superimpositions closely correspond to those determined cephalometrically in extraction cases.


   Materials and methods
Top
 Summary
 Introduction
 Materials and methods
Results
 Discussion
 Conclusion
 References
 

Sample

In this retrospective investigation, the pre- (T1) and post-(T2) treatment maxillary study casts and cephalograms of 30 patients (6 males and 24 females) treated orthodontically with four premolar extractions at Kangnung, National University Dental Hospital, were studied. Details of their ages and the treatment periods are shown in Table 1.


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  		Table 1 Sample description (n = 30).

 

Cephalometric analysis

Cephalometric radiographs were taken with a cephalometric X-ray unit with a magnification of 1.1 (ASAHI CX 90 SP-II®, Kyoto, Japan). The pre- and post-treatment cephalograms were traced on conventional translucent acetate paper using a transilluminating light box. All bilateral structures were bisected. The measuring points and reference lines used for evaluating dental changes were modified from those described by Ricketts (1975)Go and Pancherz (1984Go; Figures 1 and 2). On the pre-treatment tracing, a co-ordinate system was established with the occlusal plane (OL), a line through the central maxillary incisor tip and the mesio-buccal cusp tip of the first maxillary molar, as the X-axis, and the occlusal plane perpendicular (OLP) through sella as the Y-axis. The co-ordinate axes were transferred from the pre- to the post-treatment tracing by superimposition along the palatal plane registered at ANS. Positional changes in the maxillary incisor tip and the mesio-buccal cusp tip of the first maxillary molar were evaluated. The net antero-posterior and vertical changes in landmarks were defined as the distances between the pre- and post-treatment landmarks parallel to the OL (X-axis) and the OLP (Y-axis), respectively (Figure 2). The measurements were made to the nearest 0.5 mm. To test the reliability of the measurements, 10 radiographs were re-traced and re-digitized again after an interval of at least 2 weeks by one author (JYL). The method error was calculated from the repeated measurements using Dahlberg's (1940)Go formula. The mean tracing error of length was 0.27 mm.


Figure 1
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  		Figure 1 Superimposition of the maxilla along the palatal plane registered at ANS according to Ricketts (1975)Go.

 

Figure 2
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  		Figure 2 Reference co-ordinate system for cephalometric superimposition on the palatal plane. X-axis: a line through the maxillary central incisor tip and the mesio-buccal cusp tip of the first maxillary molar on the initial cephalogram; Y-axis: plane perpendicular to X-axis through sella; {Delta}x: horizontal movement of the mesio-buccal cusp tip of upper first molar; {Delta}y: vertical movement of the maxillary central incisor tip.

 

3D scanning

The scanning method used in this study has been described previously (Cha et al., 2002Go). 3D scanning of the maxillary dental casts was performed using INUS dental scanning solution®, which consists of a 3D scanner (topometric and photometric 3D scanner, Breuckmann Inc., Germany, resolution 8 µm, reliability ±15 µm) and a 3D reverse modelling software program (Rapidform 2002®, INUS Technology Inc., Seoul, South Korea).


3D model superimposition and co-ordinate system

To measure orthodontic tooth movement, pre- and post-treatment scans were superimposed on the surface across the palate. This procedure, designated as a 3D surface-to-surface matching (best-fit method), employed a least-mean-squared technique using a function of the Rapidform 2002® (Commer et al., 2000Go; McDonagh et al., 2001Go; Cha et al., 2002Go; Figure 3a). The accuracy of measurement was evaluated by calculating the superimposition discrepancies between pre- and post-treatment 3D models. The results were as follows: mean error 0.0399 mm, standard error 0.0289 mm, and standard deviation 0.1583 mm. Therefore, the surface-to-surface matching (best-fit method) is sufficiently accurate for dental cast analysis.


Figure 3
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  		Figure 3 Superimposed model with differences displayed in colours on a millimetre scale. (a) Reference surface for superimposition. (b) The degree of surface matching is described by the colour-coding system.

 
A change from 0 to 2.1 is represented by a colour progression from blue to red (Figure 3b). A co-ordinate system modified from the proposal of Ashmore et al. (2002)Go was established on the pre-treatment digital model with the junction of the incisive papilla and palatine raphe as the origin (0, 0, 0), resulting in an X-, Y-, Z-axis and three planes (Figure 4).


Figure 4
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  		Figure 4 The co-ordinate system. (a) X-Y sagittal plane is made up of two arbitrary points on the mid-palatal suture and the junction of the inclusive papilla and palatine raphe (PMRJ). (b) X-Z horizontal plane is the section inclusive of PMRJ, perpendicular to the sagittal plane and parallel to the occlusal plane constructed by connecting the buccal cusp tips of the right and left maxillary first and second premolars and mesio-buccal cusp tips of the first molars using the best-fitting process. (c) The Y-Z frontal plane is the section inclusive of PMRJ and perpendicular to both the sagittal and the horizontal planes.

 

Measuring and statistics

The measuring points in the co-ordinate system of the superimposed 3D models were the midpoint on the edge of the upper right and left central incisor and the mesio-buccal cusp tip of the right and left upper molar (Figure 5). Measurements of tooth movement along the X- and Y-axis in the superimposed digital models of left and right teeth were averaged as in the cephalometric analysis. This study excluded measurements of tooth movements along the Z-axis, i.e. movements in the frontal plane. Positive values along the X- and Y-axis indicated mesial and extrusive tooth movements.


Figure 5
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  		Figure 5 Tooth movement of superimposed three-dimensional models. (a) Palatal view and (b) sagittal view (red: before treatment, blue: after treatment).

 
The mean sagittal and vertical molar movements measured on the cephalometric radiographs were compared with that measured on the superimposed 3D models. Similarly, the mean horizontal and vertical incisor movements measured on the cephalometric radiographs were compared with those measured on the superimposed models. Paired t-tests and correlation analysis were performed to determine whether a significant difference existed between the two measuring techniques. The null hypothesis assumed a zero difference between the cephalometric variables and the corresponding 3D model variables.


   Results
Top
 Summary
 Introduction
 Materials and methods
 Results
Discussion
 Conclusion
 References
 
The results are shown in Table 2. Descriptive statistics [including mean, standard deviation, and range (Min, Max)] were calculated for the 3D model variables (averages for the right and left sides) and the cephalometric variables that describe upper molar and upper incisor movement. Paired t-tests showed no statistical differences (P > 0.05) between the vertical and horizontal upper first molar or upper incisor movements assessed by cephalometric and 3D model superimposition.


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  		Table 2 Paired t-tests comparing (a) central incisor and (b) first molar movement measured from cephalograms and three-dimensional digital models.

 
Pearson correlation coefficients between 3D variables and cephalometric variables are also shown in Table 2. Correlation analysis revealed that the r value was highest at 0.994 for upper molar horizontal movement and lowest at 0.932 for upper molar vertical movement. Figures 6a–d show the regression lines for tooth movements as determined cephalometrically and by 3D model superimposition. Adequate correlations were obtained for all tooth movements. This means that the molar and incisor movements were the same, whether measured from the 3D digital model or by cephalometric superimposition.


Figure 6
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  		Figure 6 (a–d) Scattergrams and regression lines for the central incisor and first molar movements measured on the cephalograms and three-dimensional digital models.

 

   Discussion
Top
 Summary
 Introduction
 Materials and methods
 Results
 Discussion
Conclusion
 References
 
Orthodontic study models have played an important role as an essential component of 3D diagnostic records. However, model analysis is performed manually with a number of limitations in terms of accuracy and measuring ability. In other words, analysis of a 3D object by simple linear measurements not only fails to consider diagnostic information such as surface morphology and volumetric palatal changes but also requires considerable time and energy. Efforts have been made to overcome these problems. In particular, photography (Schirmer and Wiltshire, 1997Go), holographic technology (Ryden et al., 1982Go), and a precise 3D co-ordinate measuring technique (Almeida et al., 1995Go) were introduced to improve conventional model analysis. More recently, laser scanning was introduced to digitize the dental arch (Motohashi and Kuroda, 1999Go; Hayashi et al., 2002, 2004Go). However, these methods were applied only for research because of the slow rate of raw data acquisition and operational difficulties.

In this study, a maxillary model was reconstructed using a 3D scanner. There are basically two types of optical 3D scanners: the white-light pattern projection type and the laser type (point, stripe). The white-light pattern projection type scanner is a system for scanning objects of varying size. Using fringe projection techniques, white-light pattern type scanners produce very dense, accurate point cloud data which permit rapid surface and tool path generation. On the other hand, laser-type scanners using white light detects diverse linear patterns projected on an object with a CCD camera and then creates 3D image through triangulation and image processing.

In this study, a stripe pattern projection type 3D scanner was used since it is less affected by light interferences on white stone models, data acquisition can be carried out in a relatively short time, and measurement can be performed at a resolution as high as 8 µm, depending on the degree of calibration, which is well beyond what is normally required for measuring the mesio-distal diameter of a tooth or the arch width or length in model analysis. It took approximately 10 minutes to complete the scanning of a maxillary model. The scanning speed increases when the resolution is reduced and is expected to improve even more by further advancements of hardware.

Several investigators have studied the potential use of the palatal rugae for superimposition of serial models (Peavy and Kendrick, 1967Go; van der Linden, 1978Go; Ashmore et al., 2002Go). Palatal rugae form their pattern within 12–14 weeks of intrauterine life and have been assumed to remain stable throughout life. They have thus served as reference points when studying serial casts (Lebret, 1962Go).

Friel (1949)Go demonstrated a growth-dependent forward movement of the dentition in relation to the rugae. Peavy and Kendrick (1967)Go used a symmetrograph to study 15 subjects in whom the first premolars were extracted and concluded that the lateral end of the rugae close to the teeth tended to follow the teeth in the sagittal plane and thus could not be used as a reference point. They recommended the so-called O point on the midsagittal plane for reference on the assumption that this part of the palate is least affected by growth. Investigations by Almeida et al. (1995)Go, using the reflex metrograph, suggest that the transverse offsets and distances between medial rugae points are generally stable, particularly for the first rugae. They, therefore, recommend this area as a reference point for the superimposition of serial models. As a reference plane, however, they used only the median palatal raphe on the assumption that it is a stable area. This limits the interpretation of the results, especially for sagittal changes of the rugae. In a study measuring antero-posterior molar movement, Hoggan and Sadowsky (2001)Go reported that the median end of the third palatal rugae landmark can be used as reliably as cephalometric superimposition. Ashmore et al. (2002)Go employed a mechanical 3D digitizer for a 3D analysis of molar movement during headgear treatment. They used their own specific co-ordinate system but again superimposed models on the palatal rugae.

The above-mentioned results indicate that the evaluation of tooth movement using the palatal rugae has many clinical limitations because of the difficulty in establishing reference points and the complicated measuring process (Cha et al., 2002Go). In addition, 3D changes of the rugae have not been considered in most previous studies. Errors may also derive from two-dimensional measurements of the 3D curvature of the palatal vault. Moreover, there seems to be no consensus as to the stability of the palatal rugae in conjunction with growth or treatment. Future research should evaluate the 3D positional stability of palatal rugae using another stable reference plane. The microscrew used to reinforce anchorage may serve as an alternative reference landmark, but only in limited cases (Cha et al., 2002Go).

3D surface scanning systems have been suggested for assessing morphological changes in maxillo-facial surgery or dentofacial orthopaedics (Arridge et al., 1985Go; Moss et al., 1987Go, 1988Go, 1994Go, 1995Go; Ayoub et al., 1998Go; Schwenzer et al., 1998Go; Nute and Moss, 2000Go; McDonagh et al., 2001Go; Ismail et al., 2002Go). In the present study, the possibility of clinically assessing tooth movements with a 3D registration method, which is mainly used in the field of engineering, was evaluated. Registration refers to a process of merging scanned images from many different angles to create a single 3D image (Rekoff, 1985Go). The software used in this study automatically extracted shape information from overlapping images as the position that minimizes the mean distance (Figures 3 and 5). On superimposed models, an area of less than 0.2 mm difference, represented by an antero-posterior spread of blue colour, was the constant section of the midsagittal contour. This confirms the findings of Korkhaus (1959)Go, whose line of superimposition was the midsagittal curvature from a few millimeters behind the incisive foramen to the palatal region near the first molar.

The mean horizontal and vertical incisor and molar movements measured by the 3D scanned superimposed model did not differ statistically from those obtained by cephalometric assessment (Table 2). There was a high correlation between cephalometric and 3D measurements (Table 2). These results suggest that the 3D maxillary superimposition model is clinically applicable and just as reliable as cephalometric superimposition for assessing orthodontic tooth movement in extraction subjects. Further studies may be required for the assessment of subjects treated with expansion mechanics or for the mandible.With the co-ordinate system used in this study, it is likely that a simple mouse click will enable computer-assisted evaluation not only of the simple mesio-distal or vertical movements observed on cephalograms but also of all 3D movements, including transverse movements or rotation of diverse dental landmarks. 3D models have opened up many new possibilities ranging from novel treatment modalities to treatment evaluation methods that were until recently still at the theoretical stage. The problem of storing orthodontic casts could thus be solved, and the internet-based data transmission system will facilitate an efficient and convenient exchange of orthodontic data and patients’ records.


   Conclusion
Top
 Summary
 Introduction
 Materials and methods
 Results
 Discussion
 Conclusion
References
 
This study assessing tooth movements for the upper molars and incisors in extraction cases was carried out to compare two dimensional cephalometric and 3D digital model superimpositions. The mean incisor and molar movement measurements did not differ statistically between cephalometric and 3D model superimposition. These findings suggest that 3D digital model superimposition is clinically as reliable as cephalometric superimpositions for assessing orthodontic tooth movement.


   Acknowledgement
 
The authors would like to thank the INUS technology chief, Mr S. H. Bae, and his research staff for their support.


   References
Top
 Summary
 Introduction
 Materials and methods
 Results
 Discussion
 Conclusion
 References
 

    Almeida MA, Phillips C, Kula K, Tulloch C. Stability of the palatal rugae as landmarks for analysis of dental casts. Angle Orthodontist (1995) 65:43–48.[ISI][Medline]

    Arridge S, Moss JP, Linney AD, James D R. Three dimensional digitization of the face and skull. Journal of Maxillofacial Surgery (1985) 13:136–143.[CrossRef][ISI][Medline]

    Ashmore JL, Kurland BK, King GJ. A 3-dimensional analysis of molar movement during headgear treatment. American Journal of Orthodontics and Dentofacial Orthopedics (2002) 121:18–29.[CrossRef][ISI][Medline]

    Ayoub AF, Siebert P, Moos KF, Wray D, Urquhart C, Niblett TB. A vision-based three-dimensional capture system for maxillofacial assessment and surgical planning. British Journal of Maxillofacial Surgery (1998) 36:353–357.[CrossRef]

    Cha BK, Lee JY, Bae SH, Park DI. Preliminary study of future orthodontic model analysis: the orthodontic application of 3D reverse engineering technologies. Journal of the Korean Dental Association (2002) 40:107–117.

    Commer P, Bourauel C, Maier K, Jäger A. Construction and testing of a computer-based intraoral laser scanner for determining tooth positions. Medical Engineering & Physics (2000) 22:625–635.[CrossRef][ISI][Medline]

    Dahlberg G. Statistical methods for medical and biological students (1940) New York: Interscience Publications.

    Fischer-Brandies H, Orthuber W, Laibe J, Menzel E. Continuous arch wire technique using the bending art system. Journal of Orofacial Orthopedics (1997) 58:198–205.[CrossRef][Medline]

    Friel S. Migration of teeth. Dental Record (1949) 69:74–84.

    Ghafari J, Baumrind S, Efstratiadis SS. Misinterpreting growth and treatment outcome from serial cephalographs. Clinical Orthodontics and Research (1998) 1:102–106.[Medline]

    Hayashi K, Arakib Y, Uechia J, Ohnoc H, Mizoguchia I. A novel method for the three-dimensional (3-D) analysis of orthodontic tooth movement—calculation of rotation about and translation along the finite helical axis. Journal of Biomechanics (2002) 35:45–51.[CrossRef][ISI][Medline]

    Hayashi K, Uechia J, Murata M, Mizoguchi I. Comparison of maxillary canine retraction with sliding mechanics and a retraction spring: a three-dimensional analysis based on a midpalatal orthodontic implant. European Journal of Orthodontics (2004) 26:585–589.[Abstract/Free Full Text]

    Hoggan BR, Sadowsky C. The use of palatal rugae for the assessment of anteroposterior tooth movements. American Journal of Orthodontics and Dentofacial Orthopedics (2001) 119:482–488.[CrossRef][ISI][Medline]

    Ismail SF, Moss JP, Hennessy R. Three-dimensional assessment of the effects of extraction and nonextraction orthodontic treatment on the face. American Journal of Orthodontics and Dentofacial Orthopedics (2002) 121:244–256.[CrossRef][ISI][Medline]

    Korkhaus G. Present orthodontic thought in Germany. American Journal of Orthodontics (1959) 45:881–900.[CrossRef]

    Lebret L. Growth changes of the palate. Journal of Dental Research (1962) 41:1391–1404.[Abstract/Free Full Text]

    McDonagh S, Moss JP, Goodwin P, Lee RT. A prospective optical surface scanning and cephalometric assessment of the effect of functional appliances on the soft tissues. European Journal of Orthodontics (2001) 23:115–126.[Abstract/Free Full Text]

    Mehl A, Hickel R. Current state of development and perspectives of machine-based production methods for dental restorations. International Journal of Computerized Dentistry (1999) 2:9–35.[Medline]

    Mormann WH, Brandestini M, Lutz F. The Cerec system: computer-assisted preparation of direct ceramic inlays in 1 setting. Quintessenz (1987) 38:457–470.[Medline]

    Moss JP, Linney AD, Grindrod SR, Arridge SR, Clifton JS. Three-dimensional visualization of the face and skull using computerized tomography and laser scanning techniques. European Journal of Orthodontics (1987) 9:247–253.[Abstract/Free Full Text]

    Moss JP, Grindrod SR, Linney AD, Arridge SR, James D. A computer system for the interactive planning and prediction of maxillofacial surgery. American Journal of Orthodontics and Dentofacial Orthopedics (1988) 94:469–475.[CrossRef][ISI][Medline]

    Moss JP, McCance AM, Fright WR, Linney AD, James DR. A three-dimensional soft tissue analysis of fifteen patients with Class II, division 1 malocclusions after bimaxillary surgery. American Journal of Orthodontics and Dentofacial Orthopedics (1994) 105:430–437.[ISI][Medline]

    Moss JP, Linney AD, Lowey MN. The use of three-dimensional techniques in facial esthetics. Seminars in Orthodontics (1995) 1:94–104.[CrossRef][Medline]

    Motohashi N, Kuroda T. A 3D computer-aided design system applied to diagnosis and treatment planning in orthodontics and orthognathic surgery. European Journal of Orthodontics (1999) 21:263–274.[Abstract/Free Full Text]

    Nute SJ, Moss JP. Three-dimensional facial growth studied by optical surface scanning. Journal of Orthodontics (2000) 27:31–38.[Abstract/Free Full Text]

    Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. American Journal of Orthodontics (1984) 85:125–134.[CrossRef][ISI][Medline]

    Peavy DC, Kendrick GS. The effects of tooth movement on the palatine rugae. Journal of Prosthetic Dentistry (1967) 18:536–542.[CrossRef][ISI][Medline]

    Rekoff MG Jr. On reverse engineering. IEEE Transactions on Systems, Man and Cybernetics (1985) 15:244–252.[ISI]

    Ricketts RM. A four-step method to distinguish orthodontic changes from natural growth. Journal of Clinical Orthodontics (1975) 9(208–215):218–228.

    Ryden H, Bjelkhagen H, Martensson B. Tooth position measurements on dental casts using holographic images. American Journal of Orthodontics (1982) 81:310–313.[CrossRef][ISI][Medline]

    Sachdeva RC. SureSmile technology in a patient-centered orthodontic practice. Journal of Clinical Orthodontics (2001) 35:245–253.[Medline]

    Schirmer UR, Wiltshire WA. Manual and computer-aided space analysis: a comparative study. American Journal of Orthodontics and Dentofacial Orthopedics (1997) 112:676–680.[CrossRef][ISI][Medline]

    Schwenzer K, Holberg C, Willer J, Mast G, Ehrenfeld M. 3-D imaging of the facial surface by topometry using projected white light strips. Mund- Kiefer- und Gesichtschirurgie 2 (1998) (Suppl 1):S130–S134.

    van der Linden FPGM. Changes in the position of posterior teeth in relation to rugae points. American Journal of Orthodontics (1978) 74:142–161.[CrossRef][ISI][Medline]


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