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Objectives: To assess the validity of using the calibration ruler for correcting magnification of linear measurements and to explore and compare the vertical and horizontal magnification of four digital cephalometric units., Methods: An acrylic box was imaged at seven sagittal positions using four digital cephalometric units: Orthopantomograph OC100, Orthopantomograph OC200, Sirona Orthophos CD, and Sirona Orthophos DS. The true linear lengths of the phantom, corrected, and uncorrected linear lengths on the images were measured and compared. The validity of measurements using the calibration ruler was assessed. The magnification values and distortion indices were calculated and compared among the four cephalometric units., Results: For linear measurements on the mid-sagittal plane and averaged linear measurements on bilateral symmetric sagittal planes, the bias 1.96 STD of the calibration ruler ranged from 1% to 2% for the four cephalometric testing units. For linear measurements on the single lateral sagittal plane, the bias 1.96 STD ranged from 3% to 6%. The vertical scanning charge-coupled device cephalometric unit produced the greatest distortion, ranging from 1.029 to 0.964., Conclusion: The metal millimeter calibration ruler is an accurate reference for linear measurement magnification correction. Because of unpredictability and machine specificity, the magnification and distortion of a cephalometric unit should be calibrated for the estimation of cephalometric measurement error., Competing Interests: None

Sixty-nine experienced Chinese orthodontists evaluated 108 Chinese patients' facial attractiveness from set of photographs (frontal, lateral, and frontal smiling photos) taken at the end of orthodontic treatment. These 108 patients, which contained an equal number of patients with Class I, II, and III malocclusion, were randomly selected from 6 orthodontic treatment centers throughout China. Spearman rank-order correlation coefficients (rs) analyses were performed to examine agreement in ranking between all judge pairs. Pearson correlation and multivariate regression were performed to examine the correlation between cephalometric measures and end-of-treatment Photo Attractiveness Rank.96.68% judge pairs showed moderate correlated (+0.4 ≤ rs < +0.7) subjective rankings. Cephalometric measures significantly correlated with end-of-treatment Photo Attractiveness Rank included interincisal angle (r = 0.330, P < 0.05), L1/MP° (r = 0.386, P < 0.05), L1-NBmm (r = 0.451, P < 0.01), L1/NB° (r = 0.374, P < 0.05), and profile angle (r = 0.353, P < 0.05) in Class I patients with an explained variance of 32.8%, and ANB angle (r = 0.432, P < 0.01), angle of convexity (r = 0.448, P < 0.01), profile angle (r = 0.488, P < 0.01), Li to E-line (r = 0.374, P < 0.05), Li to B-line (r = 0.543, P < 0.01), and Z angle (r = 0.543, P < 0.01) in Class II patient with an explained variance of 43.3%.There was less association than expected between objective measurements on the lateral cephalograms and clinicians' rankings of facial attractiveness on clinical photography in Chinese patients. Straight-stand lower incisor was desired for facial attractiveness of Class I malocclusion; and sagittal relationship and lip prominence influence the esthetics of Class II malocclusion in Chinese population.

Objectives: To identify a stable and reproducible reference region to superimpose serial maxillary dental models in adult extraction cases., Setting and Sample Population: Fifteen adult volunteers were enrolled., Methods: To reduce protrusion, bilateral maxillary first premolars were extracted in all volunteers. Each volunteer received six miniscrews, including two loaded miniscrews used to retract anterior teeth and four unloaded miniscrews. Impressions for maxillary models were taken at T1 (1 week after miniscrew placement) and T2 (17 months later). Dental models were created and then scanned using a laser scanner. Stability of the miniscrews was evaluated, and dental models were registered using stationary miniscrews. The palatal region, where deviation was within 0.5 mm in all subjects, was determined to be the stable region. Reproducibility of the new palatal region for 3D digital model superimposition was evaluated., Results: Deviation of the medial 2/3 of the palatal region between the third rugae and the line in contact with the distal surface of the bilateral maxillary first molars was within 0.5 mm. Tooth movement of 15 subjects was measured to evaluate the validity of the new 3D superimposition method. Displacements were 8.18 ± 2.94 mm (central incisor) and 2.25 ± 0.73 mm (first molar) measured by miniscrew superimposition, while values of 7.81 ± 2.53 mm (central incisor) and 2.29 ± 1.03 mm (first molar) were measured using the 3D palatal vault regional superimposition method; no significant difference was observed., Conclusion: The medial 2/3 of the third rugae and the regional palatal vault dorsal to it is a stable region to register 3D digital models for evaluation of orthodontic tooth movement in adult patients., (© 2011 John Wiley & Sons A/S.)

Objective: Cluster and discriminant analysis of the morphological characters of Angle's Class II malocclusion was performed using Procrusts standardization. The classification of craniofacial morphology with the help of morphometry and multivariate statistics was also discussed., Methods: A total of 894 class II patients were collected from the department of orthodontic, Peking University School and Hospital of Stomatology during 1997-2000. Using Procrusts standardization and cluster analysis, the samples were divided into different groups, discrimination equations were then established., Results: The samples were divided into 11 subdivisions by Procrusts superimposition and cluster analysis. Three discrimination equations were established. The accuracy rate of cross-validated grouped cases was 80.17%., Conclusion: Procrusts standardization had certain advantages in morphological classification; cluster analysis could be used in classification of Angle class II malocclusion; For different types, the differentiate rate was not the same; the discrimination equations was the foundation for future research.

Objective: To investigate hard-tissue changes in borderline cases with extraction and non-extraction during treatment and follow-up stages., Methods: Five associate professors, who were from Peking University School and Hospital of Stomatology, were asked to make judgment on the cases with full pre-treatment records for discriminating the borderline cases from extraction and non-extraction cases. Fifty-four borderline cases with full treatment records which had been out of treatment for at least 2 years were followed. Twenty-one cases with follow-up records were collected including 8 extraction cases and 13 non-extraction cases. Cephalometric measurements were preceded in IDAS (Image and Database Analysis System) software program., Results: In extraction group, significant changes of SNB, SNPg in A-P direction and that of ArGo/ANSMe, MP/SN in vertical direction were present during the follow-up stage, while the overjet was stable. In non-extraction group, only decrease of proclination of lower incisor and increase of overjet were present without any skeletal changes during the follow-up stage. In comparison of the two groups, no skeletal and dental changes showed statistically significant difference except for MP/SN and ArGoGn in pre-treatment stage, while dental characteristics in relation to upper and lower incisor (L1/NB, L1-NB, L1-AP, U1-AP, U1/L1) showed statistically significant difference between the two groups after treatment. But in follow-up stage, the skeletal and dental pattern tended to be similar for both groups only except for the proclination of lower incisor., Conclusion: The similarities of skeletal and dental pattern are demonstrated in extraction and non-extraction group before treatment. Dental changes are the major post-treatment changes in the two groups. In follow-up stage, counter-clockwise rotation of mandible is unique in extraction group, which is likely a helpful factor for stability of overjet, while lingual tipping of lower incisor in non-extraction group without skeletal changes may contribute to overjet relapse.

Objective: The aim of the present study was to evaluate the long-term skeletal and dento-alveolar stability 15 years after combined orthodontic and surgical correction of skeletal anterior open bite., Patients and Methods: Ten (8 female, 2 male) anterior openbite patients who had undergone orthodontic treatment in combination with bimaxillary surgery at Hanover Medical School were examined. Each patient had undergone Le Fort I osteotomy combined with bilateral sagittal split osteotomy (BSSO); osteosynthesis with plates and screws was carried out in the maxilla, and wire-osteosynthesis in the mandible. Cephalometric records of these patients were examined immediately before the start of the orthodontic treatment (T1), before surgery (T2), immediately after surgery (T3), medium-term after surgery, averaging 1.5 years (T4), and long-term after surgery, averaging 15 years (T5). Hasund cephalometric analysis was performed for which skeletal and dental cephalometric measurements had been taken., Results: Moderate skeletal relapse was observed 15 years after surgery. Overbite remained quite stable 15 years after surgery, which is mainly due to the upper and lower incisors' eruption over the long-term period., Conclusion: Treatment of skeletal open bite via Le Fort I and bilateral sagittal split osteotomy appears to be a clinically successful procedure providing stable results.

Objective: To establish the normal MESH diagrams of Chinese in Beijing, and to build a computerized MESH analysis system for orthodontic practice., Methods: Twenty-eight subjects with normal occlusion were selected in Beijing and their lateral cephalograms were taken at the age of thirteen and eighteen, respectively. Individual MESH diagrams were then established for each subject mainly according to Moorrees' method from the cephalograms orientated in estimated natural head position. Male and female normal MESH diagrams were created. A computerized MESH analysis system was also developed., Results: The normal MESH diagrams of Chinese in Beijing, thirteen and eighteen years old respective, were established. The computerized MESH analysis system was constructed and used in orthodontic patients., Conclusions: MESH analysis is a proportional analysis method. It can show the results directly, succinctly and holistically. It is also a favorable complement and amendment to the commonly used angle and linear X-ray analysis methods.

Objective: To compare soft-tissue morphology changes by cephalometric measurements between extraction and non-extraction orthodontic treatment in borderline cases., Methods: The samples consisted of 33 cases selected as borderline cases by 5 orthodontic specialists. They were divided into 21 extraction cases (including 13 four first premolar extraction cases and 8 four second premolar extraction cases) and 12 non-extraction cases by checking patients' treatment records. Conventional cephalometric analysis was made to compare soft tissue structures before and after orthodontic treatments and the same comparison was made between two different extraction patterns., Results: No statistical difference was found in pretreatment soft-tissue morphology between extraction and non-extraction groups divided from borderline cases. The PosBs/FH of the four first premolars extraction group was smaller than that of non-extraction group, and the Ns-Sn-Pos of the four first premolars extraction group was smaller than that of four second premolar extraction group. None of the post-treatment soft-tissue measures showed significant statistical differences between four first premolars extraction group and non-extraction group, but there were 6 items showed significant statistical differences between four second premolars extraction group and non-extraction group. Compared with extraction and non-extraction treatments, the most significant soft-tissue changes were: PosBs/FH, LL-SnPos, and Bs-EP ., Conclusion: Although pre-treatment soft-tissue morphology of second premolar extraction group was close to that of non-extraction group, the post-treatment soft-tissue morphology of first premolar extraction group became closer to that of non-extraction group. Compared with non-extraction treatment, the more significant changes caused by extraction treatment were located in the lower lip and chin, but not the upper lips.

Objective: To compare the treatment effect on the prominence of profile in borderline cases between extraction and non-extraction treatment., Methods: The sample consisting of 33 borderline cases based on the judgment of 5 orthodontic specialists was divided into three groups according to the treatment way selected by the doctor in charge of the case. Three groups comprised 12 non-extraction cases, 13 four first premolars extraction cases and 8 four second premolars extraction cases. Structure superimposition was used to measure landmarks displacements which reflect the change of profile prominence before and after orthodontic treatment using pretreatment FH plane as a frame of reference., Results: Only the prominence of upper and lower incisors showed statistically significance between the extraction and non-extraction treatments. There was no statistically significant difference between the extraction of four first premolars and second premolars., Conclusion: The main effect of extraction vs. non-extraction on profile of borderline cases is the prominence of upper and lower incisors, while their influences on upper and lower base bone and soft-tissue profile are not obvious.