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Background: This study aims to verify Bolton's values for tooth size ratios and to evaluate possible relationships to different occlusal traits using precise digital measurement methods., Materials and Methods: Including 1000 consecutively selected patients from three study centres a digital, partially automated model analysis was performed utilizing the software OnyxCeph. The measurements comprised tooth width for calculation of anterior (AR) and overall ratio (OR) as a percentage, arch width, length, perimeter, overjet, overbite, space analysis in millimetre and the assessment of the angle classification., Results: AR and OR were significantly increased compared to Bolton's ratios of 77.2% (AR) and 91.3% (OR). In the gender comparison, male patients showed larger tooth size ratios, especially in the OR. Patients with Angle Class II/1 and II/2 had smaller tooth size ratios than patients with Angle Class III and I. Thus, patients with Angle Class II/1 had the largest tooth diameters in all maxillary teeth and with Angle Class II/2 the smallest tooth sizes in the mandible. The largest tooth widths in the lower jaw were observed in the Angle Class III patient group. Furthermore, a negative correlation from AR/OR to overjet, overbite, and available space in lower jaw as well as a positive correlation to available space in upper jaw was detected., Conclusions: There is a clear correlation between the tooth size ratios and the present dysgnathia as well as other orthodontically relevant occlusal traits. This prior knowledge about our patients is extremely important to create an individualized treatment plan and enable sufficient occlusion. To achieve a functionally good occlusion with correct overjet and overbite, it is essential that the maxillary and mandibular teeth are proportional in size. Any deviation from the ideal patient in terms of tooth size, number, shape, or arch must be considered in the pre-therapeutic treatment plan in combination with the existing dysgnathia in order to be able to achieve a stable anterior and posterior occlusion with appropriate adjustments to the therapy post-therapeutically., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Craniofacial skeletal discrepancies have been associated with upper airway dimensions., Objective: To identify differences in upper airway volume across different sagittal and vertical skeletal patterns., Search Methods: Unrestricted literature searches in eight databases/registers for human studies until May 2023., Selection Criteria: Cross-sectional studies measuring upper airway volumes using three-dimensional imaging in healthy patients of different sagittal (Class I, Class II, and Class III) or vertical (normodivergent, hypodivergent, and hyperdivergent) craniofacial morphology., Data Collection and Analysis: Duplicate independent study selection, data extraction, and risk of bias assessment. Random-effects frequentist network meta-analysis was performed followed by subgroup-analyses and assessment of the quality of clinical recommendations (confidence in effect estimates) with the CINeMA (Confidence in Network Meta-Analysis) approach., Results: Seventy publications pertaining to 66 unique studies were included with 56 studies (5734 patients) contributing to meta-analyses. Statistically significant differences were found for total  pharyngeal airway volume, with Class II having decreased airway volume (-2256.06 mm3; 95% Confidence Interval [CI] -3201.61 to -1310.51 mm3) and Class III increased airway volume (1098.93 mm3; 95% CI 25.41 to 2172.45 mm3) compared to Class I. Significant airway volume reductions for Class II were localized mostly at the oropharynx, followed by the palatopharynx, and the glossopharynx. Significant airway volume increases for Class III were localized mostly at the oropharynx, followed by the intraoral cavity, and hypopharynx. Statistically significant differences according to vertical skeletal configuration were seen only for the oropharynx, where hyperdivergent patients had reduced volumes compared to normodivergent patients (-1716.77 mm3; 95% CI -3296.42 to -137.12 mm3). Airway differences for Class II and Class III configurations (compared to Class I) were more pronounced in adults than in children and the confidence for all estimates was very low according to CINeMA., Conclusions: Considerable differences in upper airway volume were found between sagittal and vertical skeletal configurations. However, results should be interpreted with caution due to the high risk of bias, owing to the retrospective study design, inconsistencies in anatomic compartment boundaries used, samples of mixed children-adult patients, and incomplete reporting., Clinical Trial Registration: PROSPERO (CRD42022366928)., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Orthodontic Society.)

Objective: To systematically evaluate all the evidence assessing variations in the depth of the curve of Spee (COS) according to the presence/absence of different dentoskeletal characteristics., Search Methods and Eligibility Criteria: The eligibility criteria were outlined following the PECO framework, as follows: studies evaluating individuals with complete permanent dentition including second molars (P), which compared a group with a certain dentoskeletal variation (E) versus another group without the variation (C), regarding the depth of the COS (O). MEDLINE (via PubMed), Scopus, Web of Science, The Cochrane Library, LILACS and BBO (via Virtual Health Library), OpenGrey, and Google Scholar were searched up to September 2021 to identify eligible reports., Data Collection and Analysis: Duplicates were removed from all the records retrieved. The selection process and data collection were performed independently by two review members. The risk of bias was also assessed independently and in duplicate, using the guideline described by Fowkes and Fulton. Several meta-analyses (α = 0.05) were conducted to estimate the mean differences (MD) or standardized mean differences (SMD) in the depth of COS between individuals presenting or not certain dentoskeletal characteristics. The certainty of evidence was assessed using the GRADE tool., Results: Thirty-five studies were selected for qualitative synthesis, and 29 of them for quantitative synthesis. All studies had methodological limitations that affected the risk of bias and increased the likelihood that results were due to chance. Syntheses showed that Class II malocclusion (SMD = 0.87; 95% CI: 0.61, 1.13; P < 0.00001; six datasets including 260 subjects analysed), Class II division 1 (SMD = 1.09; 95% CI: 0.62, 1.56; P < 0.00001; 14 datasets including 823 subjects analysed) and Class II division 2 (SMD = 2.65; 95% CI: 1.51, 3.79; P < 0.00001; eight datasets including 476 subjects analysed) had deeper COS than Class I malocclusion. The skeletal Class II also presented higher COS values than skeletal Class I (SMD = 0.57; 95% CI: 0.02, 1.12; P = 0.04; four datasets including 299 subjects analysed). Individuals with Class III malocclusion had flatter COS than the subjects having Class I malocclusion (SMD = -0.57; 95% CI: -1.07, -0.08; P = 0.02; nine datasets including 505 individuals analysed). No difference was shown in the COS depth between skeletal Class III and Class I (P > 0.05). Deep bite individuals had higher COS depth than those with normal overbite (MD = 0.61; 95% CI: 0.41, 0.82; P < 0.00001; two datasets including 250 subjects analysed). In addition, hypodivergent individuals presented deeper COS than normodivergents (SMD = 0.62; 95% CI: 0.37, 0.86; P < 0.00001; six datasets including 305 subjects analysed), and there was no significant difference in the COS depth between hyperdivergent and normodivergent individuals (P = 0.66). The certainty of evidence was rated as very low for all the syntheses., Limitations: All the quantitative syntheses included results from studies with methodological flaws. Therefore, they are potentially biased. Moreover, the evidence was also mainly affected in terms of the inconsistency of the results and the imprecision of the estimates., Conclusions: Although an apparent influence of dentoskeletal Class II, Class III malocclusion, deep bite, and the hypodivergent skeletal pattern on the depth of the COS is suggested, it is not possible to make definitive conclusions on the matter due to the very low certainty of the evidence. Further high-quality research is necessary., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: To compare the quality of orthodontic treatment between 0.018-inch and 0.022-inch slot bracket systems., Subjects and Methods: Eligible participants aged 12 years or over were allocated to the 0.018-inch or 0.022-inch slot MBT appliance (3M-Unitek, Monrovia, California, USA) using block randomization in groups of 10. Outcome measures included: 1. ABO cast-radiograph evaluation (CR-EVAL), 2. peer assessment rating (PAR) scores, 3. incisor inclination, and 4. patient perception using the Index of Orthodontic Treatment Need aesthetic component (IOTN AC) and three validated questionnaires before, during and after treatment. Parametric tests [independent samples t-test and two-way analysis of variance (ANOVA)] and non-parametric tests (chi-square with Fisher's exact tests and Mann-Whitney U-test) assessed differences between groups (P < 0.05)., Results: Of the 187 participants randomized (1:1 ratio), 34 withdrew or were excluded (protocol deviations or poor cooperation). There were 77 patients in the 0.018-inch slot group and 76 patients in the 0.022-inch slot group (overall mean age: 19.1 years). Baseline characteristics were similar between groups (P > 0.05). The mean total ABO CR-EVAL scores were 34.7 and 34.5; mean percentage PAR score reduction 74.1 per cent and 77.1 per cent; mean change for maxillary incisor inclination 2.9 degrees and 1.6 degrees and for mandibular incisor inclination 2.7 degrees and 1.4 degrees for the 0.018-inch and 0.022-inch groups, respectively. Improvement in patient perception of aesthetics after treatment was statistically significant for both groups (P < 0.05). However, there were no statistically significant differences between the two treatment groups for ABO CR-EVAL, percentage PAR score reduction, incisor inclination, and patient perception of treatment (P > 0.05). No adverse events were observed during treatment., Limitations: It was impossible to blind clinicians or patients to allocation and oral hygiene and periodontal outcomes were not assessed., Conclusions: There were no statistically or clinically significant differences in the quality of occlusal outcomes, incisor inclination and patient perception of treatment between 0.018-inch and 0.022-inch slot bracket systems., Registration: The trial was registered with ClinicalTrials.gov on 5 March 2014, registration number: NCT02080338., Protocol: The protocol was published at DOI: 10.1186/1745-6215-15-389., (© The Author(s) 2018. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: The aim of this study was to evaluate the qualitative occlusal changes in individuals with normal occlusion during a period of 47 years., Materials and Methods: The sample comprised dental models of 20 subjects with normal occlusion (8 males; 12 females) taken at 13.2 years (T1) and 60.9 years of age (T2). The occlusal features were evaluated with the objective grading system (OGS) and with the six keys to normal occlusion (SKNO). The subjects also answered a questionnaire on the aesthetic and occlusal self-perception at T2. Comparisons from T1 to T2 were performed with paired t- and McNemar tests (P less than 0.05)., Results: OGS analysis showed a significant improvement in the marginal ridge levelling and tooth buccolingual inclination. There was a significant deterioration of the antero-posterior occlusal relationship from T1 to T2. Subjects without tooth loss showed a dental alignment worsening between time points. The marginal ridges, buccolingual inclination, and interproximal contacts improved. The SKNO analysis showed a significant deterioration of the maxillary second molars buccolingual inclination and an improvement of the maxillary second molar angulation. All patients were satisfied with their smiles, and 60 per cent of the subjects had no complaints. Dental crowding caused dissatisfaction in 35 per cent of the sample., Limitations: A limitation of this study was the high prevalence of tooth loss in the sample from T1 to T2. Only 30 per cent of the subjects had no tooth loss in T2., Conclusions: The aging process slightly deteriorates some occlusal features of individuals with normal occlusion. However, most individuals were satisfied with their aesthetics and occlusal comfort at the sixth decade of life., (© The Author(s) 2018. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: No randomized controlled trial (RCT) has compared flapless piezocision-assisted corticotomy in the extraction-based orthodontic decrowding of lower anterior teeth with the conventional treatment., Objective: To evaluate the effectiveness of flapless piezocision-assisted corticotomies in accelerating lower anterior teeth alignment., Trial Design: A parallel-group RCT was conducted., Materials and Methods: Thirty-six patients (mean age 20.32 ± 1.96 years) in need of orthodontic treatment with a fixed orthodontic appliance were enrolled and randomly allocated to either the experimental or the control group. Following first premolar extraction, five radiographic-guided micro incisions and localized piezoelectric corticotomies were performed on the labial surfaces of the alveolar bone between the six anterior teeth in order to accelerate alignment for patients in the experimental group, whereas those in the control group received traditional orthodontic treatment. The overall alignment time (OAT) required to complete anterior alignment of the mandibular dental arch (OAT) was measured. Little's Irregularity Index (LII) was also calculated at monthly intervals. Randomization was performed using a software-generated list of random numbers; the recruited patients were divided into two parallel groups with a 1:1 allocation ratio. Assessor blinding was employed., Results: One hundred and eight severe dental crowding patients were evaluated for eligibility, 40 of them fulfilled the inclusion criteria. Thirty-six participants were allocated to the treatment groups randomly. One female patient was lost to follow-up from the control group, and another female patient was excluded from analysis for the experimental group. Accordingly, the results of 34 patients were statistically analyzed. OAT was reduced by 59% in the experimental group compared to the control group, with a statistically significant difference between the two groups (P < 0.001). No harms were encountered., Conclusion: Flapless piezocision technique was very effective in accelerating orthodontic tooth movement., Trial Registration: This trial was registered at Clinical Trials.gov (Identifier: NCT02977221)., (© The Author(s) 2018. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background and Objectives: Some authors have recently postulated the possibility of a unilateral contraction of the palate in patients with crossbite. This study aimed to investigate palatal dimension size and morphology in subjects with functional posterior crossbite and to localize location of the contraction through a 3D analysis procedure., Materials and Methods: A study sample (SS) of 35 subjects (mean age 9.2 ± 0.8 years), diagnosed with functional crossbite, and a control sample (CS) of 35 subjects (mean age 9.4 ± 0.9 years) without crossbite were selected for this study. The digital models of each patient were analysed to assess palatal dimension size and symmetry by measuring linear distances between primary canines (D1) and fist molars (D2) to the median palatine plane and by performing and analysing the 3D deviation between the two specular models of the palatal vault for each patient., Results: Our findings demonstrate a significantly narrower dimension of D2 for the crossbite side than at the non-crossbite side. The 3D deviation analysis demonstrates a lower matching percentage of the palatal vault models in the SS (83.36%) compared with the CS (92.82%) and a location of that the palatal contraction is at the alveolar bone level., Conclusions: It can be assumed that there is a bilateral symmetrical contraction of the palatal vault and an asymmetric contraction of the alveolar process, but further studies are needed to corroborate this hypothesis.

Background and Objectives: Apart from the primary effect of bite-blocks on tooth position, they may also influence the mandibular condylar growth. Our aim was to investigate their influence on the condylar morphology, with variable masticatory forces., Material and Methods: Fifty-two 4-week old male rats were divided into hard and soft diet groups in order to create individuals with different masticatory muscle capacity. Two weeks later, they were equally divided into bite-block and control groups. After a total of 6 weeks experimental time, the animals were sacrificed. The mandibles were scanned with high-resolution micro-CT and 3D analysis was performed on the condylar neck and head of the condyle. The volume and the length of the condylar process were measured. Statistical analysis was done with a one-way analysis of variance., Results: The use of bite-blocks decreased the length of the condylar process (P = 0.001) as well as the volume of the condylar neck (P = 0.001) and head (P = 0.006). The soft diet decreased the volume of the condylar neck (P < 0.001) and head (P < 0.001) two to three times more than the bite-blocks but did not affect the condylar process length. The interaction between the two variables was not statistically significant., Conclusions: Both the bite-block appliance and weak masticatory muscle function reduced the volume at all regions of the condylar process, although the functional factor had a substantially greater effect. However, only the bite-block appliance affected the condylar process length. In the presence of both factors, an additive effect was found but no interaction detected.

Aim: The aim of this study was to describe the longitudinal changes in facial morphology, dental arch alterations and oral functional capacities that occur in growing patients with Duchenne muscular dystrophy (DMD) in order to identify the effects of the progression of the disease., Subjects and Methods: Twelve DMD patients (6.5-17.5 years of age) and 12 matched controls were screened on two different occasions (T1 and T2), 2 years apart. Dental casts, lateral cephalometric radiographs, maximal posterior bite force and labial force were measured to determine changes in their functional capacities and dentofacial morphology. Furthermore, the thickness and echogenicity of the masseter muscle were measured during clenching., Statistical Evaluation: Unpaired t-tests were performed to evaluate the differences between the DMD patients and their healthy matched controls; paired t-tests were used to assess the changes that occurred within each group between T1 and T2., Results: Between T1 and T2 the following changes were observed: widening of the lower dental arch for the DMD patients of 2.6mm (±0.9mm) compared to a slight reduction of -0.1mm (±0.8mm) for the control group (P = 0.001). We found a statistically significant reduction of the sagittal skeletal intermaxillary relationship (ANB-angle) of 2.0° (±2.0°) in the DMD group (P = 0.012). In T1 and T2, the maximal posterior bite force and the labial force were lower for the DMD patients compared to the control group (P = 0.001), who showed an increase during this period., Conclusion: The results indicate that DMD influences the facial morphology, dental arch dimensions and oral functional capacities. The longitudinal perspective of this study revealed that the worsening of most of the measured parameters is associated with the progression of the disease. Besides the expected deterioration of the functional measurements, we found in all patients, a marked transverse increase of the posterior part of the dental arches, more in the lower than in the upper, resulting in posterior crossbites, as well as a tendency towards a skeletal Class III relationship.

Background and Objectives: There is no consensus in the literature regarding which rapid maxillary expansion (RME) design or activation rate benefits the patients the most. Therefore, the primary aim of this systematic review was to see whether there is a difference in the skeletal and dentoalveolar effects of different RME appliances in children and growing adolescents. The secondary aim was to see whether these effects are different when using different activation protocols for these appliances., Data Collection and Analysis: The search was done in three databases (PubMed, Cochrane Library, and Web of Science). The following inclusion criteria were used: randomized controlled trial, prospective controlled studies, 15 or more patients in each study, human subjects up to 18 years of age, and RME effects had to be assessed by computed tomography/cone beam computed tomography., Study Appraisal and Synthesis Methods: Quality of the methodology was classified according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines as high, moderate, or low., Results: The search resulted in 145 titles and abstracts; 109 of them were excluded based on pre-established criteria. Thirty-six full-text articles were assessed for eligibility and 18 of which satisfied the inclusion criteria. Finally, seven articles were deemed eligible for full inclusion and revealed that all appliances and protocols showed significant expansion in the mid-palatal suture. No evidence was found for the cause of dental tipping., Limitations: In this systematic review, having different age groups in each study and using different anatomical landmarks and outcome measures for assessing the skeletal and dental effects made it difficult to conduct a meta-analysis., Conclusions: There is moderate evidence that all designs produce significant expansion at the mid-palatal suture. However, lack of studies comparing appliances and protocols has been found. Finally, no evidence-based conclusions could be drawn about the appliance effect on teeth tipping., Implications of Key Findings: No appliance appears to be superior when it comes to expansion in the mid-palatal suture. Therefore, the tooth-borne appliance might be preferable until further high-quality studies conclude otherwise., Funding: The project was funded through the Department of Orthodontics, Postgraduate Dental Education Center, Region Örebro County, Örebro, Sweden., Registration: This systematic review was not registered in any external databases., (© The Author 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)

Background and Aim: Digital orthodontic model analysis is gaining acceptance in orthodontics, but its reliability is dependent on the digitalisation hardware and software used. We thus investigated intra-observer reliability and agreement / conformity of a particular digital model analysis work-flow in relation to traditional manual plaster model analysis., Materials and Methods: Forty-eight plaster casts of the upper/lower dentition were collected. Virtual models were obtained with orthoX®scan (Dentaurum) and analysed with ivoris®analyze3D (Computer konkret). Manual model analyses were done with a dial caliper (0.1 mm). Common parameters were measured on each plaster cast and its virtual counterpart five times each by an experienced observer. We assessed intra-observer reliability within method (ICC), agreement/conformity between methods (Bland-Altman analyses and Lin's concordance correlation), and changing bias (regression analyses)., Results: Intra-observer reliability was substantial within each method (ICC ≥ 0.7), except for five manual outcomes (12.8 per cent). Bias between methods was statistically significant, but less than 0.5 mm for 87.2 per cent of the outcomes. In general, larger tooth sizes were measured digitally. Total difference maxilla and mandible had wide limits of agreement (-3.25/6.15 and -2.31/4.57 mm), but bias between methods was mostly smaller than intra-observer variation within each method with substantial conformity of manual and digital measurements in general. No changing bias was detected., Conclusions: Although both work-flows were reliable, the investigated digital work-flow proved to be more reliable and yielded on average larger tooth sizes. Averaged differences between methods were within 0.5 mm for directly measured outcomes but wide ranges are expected for some computed space parameters due to cumulative error., (© The Author 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)

Objectives: This 10-year prospective study aimed to measure and evaluate the teeth position and occlusion following 10-year nocturnal use of a mandibular protruding device (MPD) in subjects with obstructive sleep apnoea (OSA) or snoring., Materials and Methods: Seventy-seven consecutive patients diagnosed with OSA/snoring were treated with an MPD. Fabrication of dental casts with jaw registration indexes in the intercuspal position was carried out at baseline and at follow-up, a construction bite was made, and an MPD was fitted. At the 10-year follow-up, all subjects (n = 74) were invited to participate. The dental casts were analysed in a series of measurements., Results: Sixty subjects were included in the follow-up examination-41 were still using the device and 19 had ceased using the MPD. The MPD users showed significant changes in all analysed variables-decrease of overjet (-1.8 mm), overbite (-1.5 mm)-except the mandibular intercanine width and the maxillary anteroposterior relationship. Subjects who had ceased using their MPD retained their initial values, with the exception of a decreased overbite. The MPD users also showed an increased number of subjects with mesio-occlusion and posterior infra-occlusion; those who had ceased using their MPD mostly retained their initial status., Conclusions: Long-term nocturnal use of an MPD may cause both favourable and unfavourable occlusion changes, such as a decrease of the overjet and overbite or posterior infra-occlusion, and these changes may continue to develop during treatment with an MPD. Subjects with a Class III relationship may not be a suitable group for treatment with an MPD due to the mesial drift of the mandibular teeth., (© The Author 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)

Objective: To evaluate the transverse relationships of the first permanent molars after the correction of posterior crossbite performed during the deciduous dentition with two different treatment protocols., Materials/methods: Ninety patients (40 males and 50 females) with posterior crossbite were treated during the deciduous dentition with either a removable expansion plate (RP group, 60 patients) or rapid maxillary expander (RME group, 30 patients). The dental casts before treatment (T0, mean age 5.1 ± 0.7 years) and after treatment, when the first permanent molars were fully erupted, (T1, mean age 7.7 ± 1.0 years) were analysed. The prevalence rates for posterior crossbite on the first permanent molars in the two groups were compared by means of chi-squared test with Yates correction. A logistic regression was performed to evaluate the factors that could influence the presence/absence of posterior crossbite on the first permanent molars., Results: Prevalence rate of posterior crossbite on the first permanent molars at T1 was 34.4 per cent in the total sample, 28.3 per cent for the RP group and 46.6 per cent for the RME group. No significant predictors for the 'presence/absence of posterior crossbite on the first permanent molars' at T1 were found., Limitations: Retrospective study., Conclusions: After treatment of posterior crossbite during the deciduous dentition phase, the first permanent molars erupted in crossbite in the 34.4 per cent of the cases. The type of treatment is not a significant predictor for the presence of posterior crossbite on the first permanent molars., (© The Author 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)

Objective: To assess the ANB angle's and Wits appraisal's diagnostic performance using an extended version of Receiver Operating Curve (ROC) analysis, which renders ROC surfaces. These were calculated for both the conventional and normalized cephalometric tests (calculated by exchanging the patient's reference landmarks with those of the Procrustes superimposed sample mean shape).The required 'gold standard' was derived statistically, by applying generalized Procrustes superimposition (GPS) and principal component analysis (PCA) to the digitized landmarks, and ordering patients based upon their PC2 scores., Methods: Digitized landmarks of 200 lateral cephalograms (107 males, mean age: 12.8 years, SD: 2.2, 93 females, mean age: 13.2 years, SD: 1.7) were subjected to GPS and PCA. Upon calculating the conventional and normalized ANB and Wits values, ROC surfaces were constructed by varying not just the cephalometric test's cut-off value within each ROC curve, but also the gold standard cut-off value over different ROC curves in 220 steps between -2 and 2 standard deviations along PC2. The volume under the resulting ROC surfaces (VUS) served as a measure of overall diagnostic performance. The statistical significance of the volume differences was determined using permutation tests (1000 rounds, with replacement)., Results: The diagnostic performance of the conventional ANB and Wits was remarkably similar for both Class I/II (81.1 and 80.75% VUS, respectively, P > 0.05). Normalizing the measurements improved all VUS highly significantly (91 and 87.2 per cent, respectively, P < 0.001)., Conclusion: The conventional ANB and Wits do not differ in their diagnostic performance. Normalizing the measurements does seem to have some merit., (© The Author 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)

Background/objective: The aim of this study was to evaluate force levels exerted by levelling arch wires with labial and lingual conventional and self-ligating brackets., Materials/methods: The tested orthodontic brackets were of the 0.022-in slot size for labial and 0.018-in for lingual brackets and were as follows: 1. Labial brackets: (i) conventional bracket (GAC-Twin, Dentsply), (ii) passive self-ligating (SL) brackets (Damon-Q®, ORMCO; Ortho classic H4™, Orthoclassic; FLI®SL, Rocky Mountain Orthodontics) and (iii) active SL brackets (GAC In-Ovation®C, DENTSPLY and SPEED™, Strite). 2. Lingual brackets: (i) conventional brackets (Incognito, 3M and Joy™, Adenta); (ii) passive SL bracket (GAC In-Ovation®LM™, Dentsply and (iii) active SL bracket (Evolution SLT, Adenta). Thermalloy-NiTi 0.013-in and 0.014-in arch wires (Rocky Mountain Orthodontics) were used with all brackets. The simulated malocclusion represented a maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis)., Results: Lingual bracket systems showed higher force levels (2.4 ± 0.2 to 3.8 ± 0.2 N) compared to labial bracket systems (from 1.1 ± 0.1 to 2.2 ± 0.4 N). However, the differences between SL and conventional bracket systems were minor and not consistent (labial brackets: 1.2 ± 0.1 N for the GAC Twin and 1.1 ± 0.1 to 1.6 ± 0.1 N for the SL brackets with 0.013-in thermalloy; lingual brackets: 2.5 ± 0.2 to 3.5 ± 0.1 N for the conventional and 2.7 ± 0.3 to 3.4 ± 0.1 N for the SL brackets with 0.013-in Thermalloy)., Limitations: This is an in vitro study with different slot sizes in the labial and lingual bracket systems, results should be interpreted with caution., Conclusions/implications: Lingual bracket systems showed higher forces compared to labial bracket systems that might be of clinical concern. We recommend highly flexible nickel titanium arch wires lower than 0.013-in for the initial levelling and alignment especially with lingual appliances., (© The Author 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)

Background: Hypofunctional occlusion is known to lead to changes in the length of roots over time. The mechanisms that drive such changes, however, are poorly understood, with most studies concentrating on juvenile rats prior to the arrest of root development. In this article, we investigated the response of the upper and lower first molar roots to lack of occlusion concentrating on time-points after the development of the roots has ceased using the mouse as a model. Mouse molar roots finish development at weaning, much earlier than rat molars, and display a similar pattern of roots in the lower and upper jaw to humans., Methods: Hypofunctional occlusion was achieved in adult mice at 5 and 9 weeks of age by flattening the cusps of the upper first molar. Mice were then sacrificed after 6 and 2 weeks, respectively, along with control littermates. microCT was used to measure root length, alveolar bone height, and the amount of tooth eruption, followed by sectioning to understand the mechanisms behind the changes at the histological level., Results: In the lower first molar, the response to hypofunctional occlusion was characterized by elongation of both the mesial root and its surrounding alveolar bone, while the distal root was unaffected. In contrast, the response of the upper first molar was characterized by over-eruption of the mesial side of the tooth without any significant change in the alveolar bone or root length. From histologic sections, it was clear that increased deposition of cellular cementum played an important role in the changes that occurred in the lower mesial root., Conclusions: In a mouse model, upper and lower molars responded differently to hypofunctional occlusion, with adult mice showing a different response to that previously reported for juvenile rats, highlighting the importance of considering age and tooth position in cases of hypofunction., (© The Author 2016. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)

Background: Of the various malocclusions, unilateral posterior crossbite has often been associated to skeletal and muscular asymmetrical growth and function., Objective: To assess, by systematically reviewing the literature, the association between unilateral posterior crossbite (UPCB) and morphological and/or functional asymmetries (i.e. skeletal, masticatory muscle electromyographic (EMG) performance, bite force, muscle thickness, and chewing cycle asymmetries)., Materials and Methods: A literature survey covering the period from January 1965 to June 2015 was performed. Two reviewers extracted the data independently and assessed the quality of the studies., Results: The search strategy resulted in 2184 citations, of which 45 met the inclusion criteria. The scientific and methodological quality of these studies was medium-low, irrespective of the association reported. In several studies, posterior crossbite is reported to be associated to asymmetries in mandibular skeletal growth, EMG activity, and the chewing cycle. Fewer data are available on bite force and masticatory muscle thickness., Conclusions: The relationship between unilateral posterior crossbite and skeletal asymmetry is still unresolved. To date, most of the studies available report a skeletal asymmetric growth. EMG activity of masticatory muscles is different between crossbite and non-crossbite sides. Subjects with UPCB show smaller bite force than non-crossbite subjects. There is no consistency of studies reporting masticatory muscle thickness asymmetry in UPCB subjects. UPCB is associated to an increase in the reverse chewing cycle. The literature available on the subject is of medium-low scientific and methodological quality, irrespective of the association reported. Further investigations with higher sample size, well-defined diagnostic criteria, rigorous scientific methodologies, and long-term control are needed., (© The Author 2016. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: Facial attractiveness is an important factor in our social interactions. It is still not entirely clear which factors influence the attractiveness of a face and facial asymmetry appears to play a certain role. The aim of the present study was to assess the association between facial attractiveness and regional facial asymmetries evaluated on three-dimensional (3D) images., Methods: 3D facial images of 59 (23 male, 36 female) young adult patients (age 16-25 years) before orthodontic treatment were evaluated for asymmetry. The same 3D images were presented to 12 lay judges who rated the attractiveness of each subject on a 100mm visual analogue scale. Reliability of the method was assessed with Bland-Altman plots and Cronbach's alpha coefficient., Results: All subjects showed a certain amount of asymmetry in all regions of the face; most asymmetry was found in the chin and cheek areas and less in the lip, nose and forehead areas. No statistically significant differences in regional facial asymmetries were found between male and female subjects (P > 0.05). Regression analyses demonstrated that the judgement of facial attractiveness was not influenced by absolute regional facial asymmetries when gender, facial width-to-height ratio and type of malocclusion were controlled (P > 0.05)., Limitations: A potential limitation of the study could be that other biologic and cultural factors influencing the perception of facial attractiveness were not controlled for., Conclusions: A small amount of asymmetry was present in all subjects assessed in this study, and asymmetry of this magnitude may not influence the assessment of facial attractiveness., (© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Aim: To evaluate maxillary and mandibular dental arch changes induced by a passive self-ligating system by analysing digital dental casts., Subjects and Methods: A sample of 25 growing patients (16 females and 9 males, mean age 12.8 years) treated with passive self-ligating brackets was compared to a sample of 25 untreated controls (15 females and 10 males, mean age 13.4 years). Sixty three-dimensional points were digitised on the maxillary and mandibular pre- and post-treatment virtual models to evaluate differences in the transverse and antero-posterior arch dimensions and in the torque values of representative anterior and posterior teeth. Statistical comparisons were performed with independent sample t-tests with Holm-Bonferroni correction for multiple tests., Results: The greatest increments in arch widths were found at the maxillary and mandibular premolar level (ranging from 2.0 to 2.2mm) and they were associated with significant increases in maxillary and mandibular arch perimeters (2.3 and 2.5mm, respectively), and in buccal crown torque of the upper premolars (with adequate torque control of all other teeth)., Conclusions: The passive self-ligating system produced a modest but statistically significant widening of both maxillary and mandibular dental arches that were associated with significant net gains in maxillary and mandibular arch perimeters., (© The Author 2016. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: Mastication is an essential function that prepares the food for swallowing and digestion and may be related to nutritional status. Thus, the aims of this study were to evaluate the masticatory parameters in overweight and obese children and the relation between bite force and anthropometric evaluation, food consistency, breast/bottle-feeding, and occlusion., Materials and Methods: The sample consisted of 204 children of both genders, age range 8-10 years, divided into normal weight, overweight, and obese. Unilateral bite force was measured using a digital gnatodynamometer with 10mm force fork. Anthropometric and nutritional evaluation involved the measurements of body mass index and skeletal muscle mass using bioelectric impedance analysis. Occlusion was evaluated as regards orthodontic treatment need and food consistency was analysed using a structured questionnaire. In addition, the time of breast- and bottle-feeding was investigated. The results were submitted to chi-square and correlation tests, analysis of variance, and multiple linear regression to determine the relation between bite force and the independent variables under study (α = 0.05)., Results: Statistical analysis showed that the time of breast- and bottle-feeding and food consistency did not differ among groups. The regression model showed that body mass index, orthodontic treatment need, and body skeletal muscle mass contributed significantly to the variation in bite force., Conclusions: Breast- and bottle-feeding behaviour and food consistency did not differ in normal-weight, overweight, and obese children. However, bite force was dependent on body skeletal muscle mass, body mass index, and orthodontic treatment need., (© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: This study aimed to quantify the patterns of shape variability and the extent and patterns of shape covariation between the upper and lower dental arch in an orthodontic population., Methods: Dental casts of 133 white subjects (61 males, 72 females; ages 10.6-26.6) were scanned and digitized in three dimensions. Landmarks were placed on the incisal margins and on the cusps of canines, premolars, and molars. Geometric morphometric methods were applied (Procrustes superimposition and principal component analysis). Sexual dimorphism and allometry were evaluated with permutation tests and age-size and age-shape correlations were computed. Two-block partial least squares analysis was used to assess covariation of shape., Results: The first four principal components represented shape patterns that are often encountered and recognized in clinical practice, accounting for 6-31 per cent of total variance. No shape sexual dimorphism was found, nevertheless, there was statistically significant size difference between males and females. Allometry was statistically significant, but low (upper: R(2) = 0.0528, P < 0.000, lower: R (2) = 0.0587, P < 0.000). Age and shape were weakly correlated (upper: R(2) = 0.0370, P = 0.0001, lower: R (2) = 0.0587, P = 0.0046). Upper and lower arches covaried significantly (RV coefficient: 33 per cent). The main pattern of covariation between the dental arches was arch width (80 per cent of total covariance); the second component related the maxillary canine vertical position to the mandibular canine labiolingual position (11 per cent of total covariance)., Limitations: Results may not be applicable to the general population. Age range was wide and age-related findings are limited by the cross-sectional design. Aetiology of malocclusion was also not considered., Conclusions: Covariation patterns showed that the dental arches were integrated in width and depth. Integration in the vertical dimension was weak, mainly restricted to maxillary canine position., (© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: To assess whether a true knowledge of crowding alters treatment decisions compared with estimates of crowding., Materials and Methods: Thirty-six orthodontists were asked to estimate crowding using visualization on eight mandibular arch study models and to indicate possible extraction choices. For each model, the intermolar widths, intercanine widths, and clinical scenarios were identical, but the true crowding varied from 0.2 to 8.4mm as to a lesser extent did the curve of Spee. Eleven orthodontists repeated the visualization exercise after 2 weeks to assess reliability. All 36 of the orthodontists were asked to repeat the treatment planning exercise on the same models, but this time was provided with the true amount of crowding in each case., Results: When the 36 orthodontists used direct visualization of the models to assess crowding, the range of their estimates of crowding increased as the crowding increased. As might be expected, they also tended to move towards extraction treatments as the crowding increased (P = 0.013, odds ratio = 3). Although the reliability of the repeat estimates of crowding were moderate, the mean estimates were greater than the true crowding for each model. When orthodontists were presented with the true amount of crowding, rather than their estimate of crowding, it had a significant effect on the decision to extract, with fewer orthodontists recommending extractions., Limitations: The principal limitation of this study is that it was a laboratory-based study and utilized just the mandibular arch model for estimation and treatment planning., Conclusions: Direct visualization may overestimate the amount of crowding present. When the true amount of crowding is known, it can lead to more consistent treatment planning, with the decision to extract fewer teeth in the borderline cases. A formal space analysis is likely to assist with treatment planning., (© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Introduction: The cervical vertebrae maturation (CVM) method is used to determine the timing of treatment of Class II malocclusion. Because its performance has not been tested in patients with Class II, the objective of this study was to evaluate the effectiveness of the CVM method in predicting craniofacial growth in Class II malocclusion., Methods: Twenty-nine untreated girls with Class II malocclusion were identified among participants of the Nijmegen Growth Study. Each girl had a series of cephalograms taken semi-annually from 9 to 14 years of age. The CVM status was established by five observers on a cephalogram taken at 9 years; mandibular and maxillary length and anterior face height were assessed on all available cephalograms. Method error was evaluated with kappa statistics and Bland-Altman (BA) plots. Regression analysis was used to determine if CVM grade can predict the amount of facial growth., Results: The mean kappa for intra-rater agreement during grading with CVM was 0.36 (fair agreement). BA plots demonstrated acceptable agreement for cephalometric measurements. The regression analysis demonstrated that the only chronologic age was associated with the facial growth. The largest effect of age was for condylion-gnathion (Cd-Gn) and articulare-gnathion (Ar-Gn)-for every additional 6 months the Cd-Gn increases by 1.8mm [95 per cent confidence interval (CI): 1.7, 1.9, P < 0.001] and Ar-Gn increases by 1.59mm (95 per cent CI: 1.52, 1.67, P < 0.001). The CVM grade could not predict the change of cephalometric variables., Conclusions: There is no evidence to support the hypothesis that the CVM method can predict the amount of craniofacial growth in girls with Class II malocclusion., (© The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: Comparison of three different retention strategies 5 years or more postretention., Design, Setting, and Participants: Randomized, prospective, single-centre controlled trial. Forty-nine patients (33 girls and 16 boys) were randomly assigned to one of three retention methods during 2 years by picking a ballot shortly before start of retention treatment. Inclusion criteria were no previous orthodontics, permanent dentition, normal skeletal sagittal, vertical, and transversal relationships, Class I dental relationship, space deficiencies, treatment plan with extractions of four premolars followed by fixed straight-wire appliance. Maxillary and mandibular Little's irregularity index (LII), intercanine and intermolar width, arch length, and overbite/overjet were recorded in a blinded manner, altogether 10 measurements on each patient. Significant differences in means within groups assessed by t-test and between groups by one-way analysis of variance., Interventions: Retention methods: removable vacuum-formed retainer (VFR) covering the palate and the maxillary anterior teeth from canine-to-canine and bonded canine-to-canine retainer in the lower arch (group V-CTC); maxillary VFR combined with stripping of the lower anterior teeth (group V-S); and prefabricated positioner (group P)., Results: Maxillary mean LII ranged from 1.8 to 2.6mm, mean intercanine width 33.6-35.3mm with a significant difference between groups V-S and P, mean intermolar width 46.8-47.4mm and mean arch length 21.8-22.8mm. Mandibular mean LII ranged from 2.0 to 3.4mm with a significant difference between groups V-S and P, mean intercanine width from 25.4 to 26.6mm, mean intermolar width from 40.8 to 40.9mm and mean arch length from 16.9 to 17.3mm. Mean overbite ranged from 1.8 to 2.7mm and mean overjet from 3.7 to 4.1mm., Limitations: A single centre study could be less generalizable., Conclusions: The three retention methods disclosed equally favourable clinical results., Trial Registration: This trial was not registered., Protocol: The protocol was not published before trial commencement., (© The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: To investigate whether individuals with high and low mandibular plane angles, respectively, have different patterns of long-term dental arch changes in adulthood., Subjects and Methods: The material comprised 16 low-angle (≤ 24.4 degree) and 10 high-angle individuals (≥38.7 degree). Mean age was 22.7 years when the first recordings were made (T1), and new recordings were made 10 (T2) and 20 (T3) years later. The individuals were orthodontically untreated except for three who had been out of retention for more than 5 years before T1. Lateral cephalograms and study casts were obtained on all three occasions., Results: For the total observation period, the greatest mean changes were observed as a 1mm decrease of lower intercanine width and arch depths in both groups. Intermolar widths increased less than 0.5mm. Upper and lower crowding increased in the range of 0.5-0.7mm in the two groups. Only small changes occurred in overjet and overbite. Differences between groups were not significant except for lower anterior arch depth which decreased more in the low-angle group, and overjet which increased in the high- and decreased in the low-angle group. During both periods the changes were generally in the same direction., Conclusion: Changes in dental arch dimensions from third to fifth decade of life are small and generally similar in individuals with high versus low mandibular plane angles. The changes are for most variables in the same direction in the two periods examined. The only significant differences between the groups are the changes in lower arch depth and overjet., (© The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: To compare the effectiveness of fixed and removable orthodontic appliances in correcting anterior crossbite with functional shift in the mixed dentition., Subjects and Methods: Consecutive recruitment of 64 patients who met the following inclusion criteria: early to late mixed dentition, anterior crossbite with functional shift, moderate space deficiency in the maxilla, i.e. up to 4mm, a non-extraction treatment plan, the ANB angle > 0 degree, and no previous orthodontic treatment. Sixty-two patients agreed to participate. The study was designed as a randomized controlled trial with two parallel arms. After written consent was obtained, the patients were randomized, in blocks of 10, for treatment either with a removable appliance with protruding springs or a fixed appliance with multi-brackets. The main outcome measures assessed were success rate, duration of treatment, and changes in overjet, overbite, and arch length. The results were also analysed on an intention-to-treat basis., Results: The crossbite was successfully corrected in all patients in the fixed appliance group and all except one in the removable appliance group. The average duration of treatment was significantly less, 1.4 months, for the fixed appliance group (P < 0.05). There were significant increases in arch length and overjet in both treatment groups, but significantly more in the fixed appliance group (P < 0.05 and P < 0.01)., Conclusion: Anterior crossbite with functional shift in the mixed dentition can be successfully corrected by either fixed or removable appliance therapy in a short-term perspective., (© The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background/objectives: Although it has been suggested that adult patients with facial asymmetry with posterior unilateral crossbite (PUXB) may have a more tilted mandibular hinge axis (MHA) than those without PUXB, whether craniofacial morphology is associated with the MHA remains unclear. The purpose of this study was to compare the craniofacial morphology and MHA in adult subjects with post-growth facial asymmetry with and without PUXB., Subjects/methods: Thirty pre-orthodontic patients (PUXB and non-PUXB groups, n = 15 each, 9 females and 6 males, mean age: 23.2 years) participated in the study. The MHA was measured by computerized axiography and duplicated on posteroanterior and submentovertex cephalometric radiographs. Morphological asymmetry was evaluated for both skeletal and dental components and positional deviation of the mandible by cephalometric analysis. The Mann-Whitney U-test and Spearman's correlation coefficient by rank were used for statistical analysis. The level of statistical significance was set at P < 0.05., Results: Significant differences in both skeletal and dental components were found between the PUXB and non-PUXB groups. In both the frontal and horizontal dimensions, the inclination of the MHA towards the mandibular shifted side was greater in the PUXB group than in the non-PUXB group., Conclusions/implications: The present findings suggest that facially asymmetric adult subjects with malocclusions associated with PUXB exhibit not only mandibular asymmetry but also remodelling of the condylar head and glenoid fossa that accompanies the three-dimensional shifting of the MHA., (© The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: To assess the estimation of crowding by orthodontists and their subsequent extraction choices., Materials and Methods: Sixty-two orthodontists were asked to quantify crowding on eight lower arch study models using their preferred method and also to indicate possible extraction choices. For each model, the intermolar widths, intercanine widths, and clinical scenarios were identical, but the true crowding varied from 0.1 to 7.5mm across the eight models as to a lesser extent did the curve of Spee. Eleven orthodontists repeated the exercise after 9 months to assess reliability., Results: The preferred method of space estimation by all of the orthodontists was direct visualization. However, the estimates of crowding were very variable. For the most crowded lower model with 7.5mm of crowding, the estimates ranged from 5 to 20mm. Extraction choices were less variable than estimates of crowding and shifted from second to first premolars as crowding increased. Estimates of crowding and treatment decisions changed with time in 28 of 33 repeat measures. Estimates of crowding were unrelated to clinical experience., Limitations: The principal limitation of this study is that it was a laboratory-based study and utilized just the lower arch model for estimation and treatment planning., Conclusions: Extraction decisions and estimates of crowding tended to vary both initially and over time but were less varied in the case of the extraction decisions. Although this may have been a reflection of the limited treatment options, perhaps reassuringly, as the degree of crowding increased, so did the likelihood of prescribing extractions and the decisions generally shifted from second to first premolars. How orthodontists estimate crowding and make subsequent extraction choices is important and has potential medico-legal implications., (© The Author 2013. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: To evaluate and compare the effectiveness of rapid maxillary expansion (RME) and slow maxillary expansion (SME)., Materials and Methods: PubMed, Embase, Web of Science, CENTRAL, ProQuest Dissertations & Theses, ClinicalTrial.gov, and SIGLE were searched from January 1980 to October 2012 for randomized or non-randomized controlled trials. The processes of study search, selection, and quality assessment were conducted independently and in duplicate. Original outcome data underwent statistical pooling through Review Manager 5., Results: Fourteen eligible studies were finally included and two interventions (RME and SME) studied. Four outcomes (maxillary intermolar width, maxillary intercanine width, maxillary interpremolar width, and mandibular intermolar width) during three time periods (expansion, retention, and net change) were statistically pooled. The sensitivity analysis revealed that the results from the meta-analysis were generally robust. Egger's test and Begg's test detected no publication bias except for maxillary intercanine width in expansion period for SME versus control., Conclusions: SME is effective in expanding maxillary arch, while we cannot determine its effectiveness in mandibular arch expansion. RME is effective in expanding both maxillary and mandibular arches. Furthermore, SME is superior to RME in expanding molar region of maxillary arch, while similar with RME in mandibular arch expansion. However, we cannot compare their effectiveness in maxillary anterior region.

The aim of the present study was to investigate and compare the effects of conventional Hyrax screw treatment and memory screw treatment on skeletal and dentoalveolar structures. Thirty-two patients with maxillary transversal deficiency were divided into two groups. The memory-screw group included 17 patients (nine females and eight males), while the Hyrax-screw group comprised 15 patients (eight females and seven males). Mean ages of the subjects in the memory-screw and Hyrax-screw groups were 13.00 ± 1.29 and 12.58 ± 1.50 years, respectively. Plaster models and postero-anterior cephalograms were taken from the patients at the beginning of the treatment (T1) and at the end of expansion (T2) and retention periods (T3). The mean expansion period was 7.76 ± 1.04 days in the memory-screw group and 35.46 ± 9.39 days in the Hyrax-screw group. 'Shapiro-Wilk Normality test' was used to determine whether the investigated parameters were homogeneous or not. To determine the treatment changes within the group, 'paired t-test' and 'Wilcoxon signed-ranks test' were applied to the homogeneous and non-homogeneous parameters, respectively. Comparison between the groups was carried out using 'Student's t-test' for homogeneous parameters and 'Mann-Whitney U-test' for the rest. Rapid maxillary expansion was carried out successfully in both the groups. However, the use of memory screw may be advantageous because it shortens the maxillary expansion period, provides additional expansion in the retention period, and generates light forces relative to the conventional Hyrax screw.

The aim of this project was to study the impact from Turner syndrome (TS) karyotype and age on dental arch morphology and palatal height and to compare the variables in TS with reference data from non-TS females with normal occlusion. Plaster casts from 76 females with TS (6-50 years) were analysed with respect to dentoalveolar arch dimensions and palatal height. The TS females were divided into the karyotype categories: i) 45,X ii) 45,X/46,XX iii) isochromosome, and iv) other. The 45,X/46,XX karyotype exhibited fewer statistically significant variables differing from the reference group compared with other karyotypes. TS females showed increased dentoalveolar depths, decreased maxillary but increased mandibular width, decreased posterior segments, and decreased mandibular circumference compared with the reference group. In opposition to previous reports, the palatal height did not differ compared with non-TS females. Age had an impact on nine of the variables. We conclude that the present dental arch deviations are reflecting the high frequency of malocclusions reported in TS and the subsequent need for orthodontic treatment, which might possibly be lower in the 45,X/46,XX karyotype. The palatal height did not differ from the reference group, but instead the narrow maxilla might contribute to an illusion of a higher palate. We therefore suggest using the nomination 'narrow palatal vault' instead of the commonly used term 'high palatal vault'.

The aim of this study was to evaluate the influence of prolonged sucking habits and mouth breathing on palatal vault morphology in a group of subjects with unilateral functional crossbite [crossbite (CB) group] compared with a group of subjects with normal occlusion [non-crossbite (NCB) group]. A sample of 80 Caucasian subjects (51 CB and 29 NCB; aged 5.3 ± 0.8 years) in the deciduous dentition was selected. A questionnaire regarding the subject's sucking habits was answered by the parents. Any sucking habit that lasted more than 24 months was considered as a prolonged sucking habit. The breathing pattern was assessed by an experienced otorinolarygologist and was classified either mainly nose or mouth breathing. Intercanine and intermolar distances and palatal surface area and volume were recorded three dimensionally on study casts. Univariate and multivariate analyses were employed. Posterior CB was negatively correlated with all the dental and palatal parameters (P < 0.01) with the exception of the palatal surface area that did not reach the statistical significance. Only prolonged sucking habits (but not mouth breathing) was a significant risk indicator for unilateral functional CB (P < 0.001). However, the prolonged sucking habits were not significantly correlated with any of the investigated parameter, and mouth breathing was negatively correlated with the intermolar distance only. Therefore, maxillary constriction in unilateral functional CB might not be influenced by the presence or absence of prolonged sucking habits or mouth breathing.

Dentoalveolar changes in adulthood have not been extensively documented. Such changes may have important implications for the long-term stability of orthodontic treatment. To analyse occlusal and dentoalveolar changes in adults from the age of 20 years to the age of 60 years. The material comprised 18 Swedish dentists, 16 men and 2 women, with no missing teeth and no prosthodontic or orthodontic treatment. Measurements were recorded on study casts made between 1949 and 1989 at the Department of Stomatognathic Physiology at the Faculty of Odontology in Malmö, thus documenting changes over an average period of 38.4 years. Malocclusion traits, overbite, overjet, dental arch length and width, and Little's irregularity index were registered. There was a significant increase in Little's irregularity index in the mandible (1.0 mm, P < 0.01) and a decrease in arch length in both jaws (0.5-0.9 mm, P < 0.05). The maxillary and mandibular intercanine widths decreased by 0.8 and 1.0 mm, respectively (P < 0.001). The malocclusion traits, overbite, and overjet remained unchanged during the observation period. The results confirm that dentoalveolar changes occur as a continuous process throughout adult life. The findings of potential clinical importance are decreases in arch length and depth, resulting in a decrease in intercanine width and an increase in anterior crowding. In clinical orthodontic practice, these findings have important implications for treatment planning and long-term stability after orthodontic treatment.

The aim of this study was to assess the effect of bracket type on the labiopalatal forces and moments generated in the sagittal plane. Incognito™ lingual brackets (3M Unitek), STb™ lingual brackets (Light Lingual System; ORMCO), and conventional 0.018 inch slot brackets (Gemini; 3M Unitek) were bonded on three identical maxillary acrylic resin models, with a palatally displaced right lateral incisor. The transfer trays for the indirect bonding of the lingual brackets were constructed in certified laboratories. Each model was mounted on the orthodontic measurement and simulation system and ten 0.013 inch CuNiTi wires were used for each bracket type. The wire was ligated with elastomerics and each measurement was repeated once after re-ligation. The labiopalatal forces and the moments in the sagittal plane were recorded on the right lateral incisor. One-way analysis of variance and post hoc Scheffe pairwise comparisons were used to assess the effect on bracket type on the generated forces and moments. The magnitude of forces ranged from 1.62, 1.27, and 1.81 N for the STb, conventional, and Incognito brackets, respectively; the corresponding moments were 2.01, 1.45, and 2.19 N mm, respectively. Bracket type was a significant predictor of the generated forces (P < 0.001) and moments (P < 0.001). The produced forces were different among all three bracket types, whereas the generated moments differed between conventional and lingual brackets but not between lingual brackets.

In orthodontic diagnosis and treatment planning, an accurate antero-posterior measurement of jaw relationships is critically important. Previously described angular and linear measurements can be inaccurate because of their dependency on various factors. The purpose of this study was to introduce a new cephalometric measurement, named the W angle, to assess the sagittal relationship between maxilla and mandible with accuracy and reproducibility. This angle uses three skeletal landmarks--point S, point M, and point G--to measure an angle that indicates the severity and the type of skeletal dysplasia in the sagittal dimension. One hundred and forty-two pre-treatment cephalometric radiographs of patients between the age of 15 and 25 years were selected. They were again subdivided into Classes I, II, and III groups on the basis of Beta angle, Wits appraisal, and ANB angle. The W angle was measured between the perpendicular from point M on S-G line and the M-G line. The mean and the standard deviation for the W angle were calculated. After using the one-way analysis of variance and the Newman-Keuls test, receiver operating characteristics curves were obtained. Results showed that a patient with a W angle between 51 and 56 degrees can be considered to have a Class I skeletal pattern. With an angle less than 51 degrees, patients are considered to have a skeletal Class II relationship and with an angle greater than 56 degrees, patients have a skeletal Class III relationship.

The purpose of this study was to investigate the prevalence and severity of occlusal asymmetries in the molar and canine regions in a large population-based sample of adolescent Kuwaitis. Using a stratified cluster sampling method, 1299 Kuwaiti adolescents (674 boys mean age 13.3 years and 625 girls mean age 13.2 years), representing approximately 6.7 per cent of that age stratum in the population, were examined clinically for sagittal molar and canine relationships, with a view to recording half and full-step asymmetries. In this sample, 1244 subjects were examined clinically, while for the remaining 55, pre-treatment study models were assessed. All subjects were in the early permanent dentition stage. Descriptive statistical analyses were used to determine the proportion of different molar and canine asymmetries. Antero-posterior asymmetries were found to be a distinctive and common feature of the dental arches, with half-step outweighing full-step asymmetries both in the anterior and posterior regions. The total prevalence of an asymmetric molar or canine relationship was 29.7 and 41.4 per cent, respectively, with more than 95 per cent falling in the mild category. Patient gender did not influence the prevalence or magnitude of asymmetry. The results showed a clinically significant prevalence of asymmetric molar and canine relationships, which were mainly in the category of half-step asymmetry. Class II half and full-step asymmetries were more prevalent than Class III asymmetries in the molar and canine regions.

This study aimed to evaluate the malocclusions of patients with a cleft lip and/or palate (CLP) and to compare malocclusion characteristics between subjects with a pre-foramen incisor cleft (PIC) and a trans-foramen incisor cleft (TIC). A cross-sectional study was conducted of 117 cleft patients (53 per cent male) aged 6-37 years (mean age 14.7 ± 7.4 years) who attended the Dental Specialty Center in the city of Fortaleza, Brazil, between 2004 and 2007. Oral clefts were classified and radiographic examinations and dental casts were analysed to determine malocclusions and facial patterns. Malocclusion measurements were compared between the PIC and TIC groups by Mann-Whitney and Fisher's exact tests. The percentage of subjects with PIC, TIC, post-foramen incisor cleft, and rare cleft were 20.5, 73.5, 5.1, and 0.9 per cent, respectively. The prevalence of malocclusions in subjects with a CLP was 82.1 per cent (molar relationships Classes II and III) in 6- to 12-year-olds, and a severe malocclusion [dental aesthetic index (DAI)] was observed in all patients aged 13 years and above. The frequency of patients with a normal canine relationship, open bite, and anterior crossbite was higher in the PIC group than in the TIC group (6-12 years). Patients aged 13 years and above in the PIC group showed lower means for the largest anterior maxillary irregularity, higher means for positive anterior mandibular overjet, a lower frequency of crowding in the anterior incisal segments, and a normal antero-posterior molar relationship compared with the TIC group. Severe malocclusions were prevalent in subjects with a CLP. Subjects with a TIC have higher prevalence of malocclusions than those with a PIC.

The aim of this retrospective study was to cephalometrically evaluate and compare the skeletal and dental effects of a transverse sagittal maxillary expander (TSME) and a Hyrax-type expander (RME) in children with maxillary hypoplasia. Fifty subjects (26 males and 24 females), aged from 6 to 15 years, with a maxillary crossbite caused by basal apical narrowness, were divided into two equal groups. Twenty-five were treated with a TSME and the other 25 with a RME. For each patient, a lateral cephalogram was obtained before treatment (T0) and at the end of the retention period (T1). Changes in the two groups during the observation period were calculated, compared, and statistically analysed with a paired samples t -test. In the TSME group, SNP-A, I SN, and I FH and in the RME group SN-SNP.SNA, N-Me, and U6.PP displayed a statistically significant increase (P < 0.05). The increase in SNP-A, I SN, and I FH in the TSME group was significantly greater following treatment than in the RME group. The results support the use of the TSME to produce skeletal changes and dentoalveolar modification and to correct maxillary hypoplasia. It was also demonstrated that in patients with an anterior open bite, the use of the TSME is not contraindicated as the anterior vertical dimension did not increase significantly.

The purpose of this research was to investigate whether anterior dental alignment in 8- to 10-year-old children influences the first impressions of their peers, and to verify the validity of the tested method. From colour photographs of two attractive children, one male and one female, Adobe Photoshop 5.0 was used to alter the images and create three versions of each photograph: one with good anterior dental alignment (OK smile), a second with proclination of the upper incisors (P-type smile), and finally one with moderate-to-severe anterior crowding (C-type smile). The six different photographs were shown to 121 subjects with mean age of 9.2 years (65 females and 56 males). Each subject was asked to view one photograph and subsequently respond to a questionnaire, the 'Smile perception questionnaire for children between the ages of 8 and 10' (SPQ 8-10), composed of 13 questions with graded responses. The responses for each photograph were analysed using linear regression analysis to determine the questionnaires validity as a whole and to investigate five area of common interest (honesty, intelligence, personal happiness, pleasantness, and extroversion). The results demonstrated that the questionnaire was reliable both from an internal coherence standpoint and from a test-retest reliability perspective. Data regarding the five areas of interest showed that 8- to 10-year-olds viewed their peers with well-aligned teeth more favourably as far as honesty, personal happiness, and intelligence were concerned. However, there was no statistically significant difference with regard to pleasantness and extroversion in children with harmonious, as opposed to crowded or proclined anterior teeth.

Summary: The purpose of the present research was to compare the normal average values of mesiodistal axial angulation, with the mesiodistal axial angulation of canines, premolars and mandibular molars in individuals with and without the presence of the mandibular third molars. Panoramic radiographs of 19 male and 21 female Caucasians, with a mean age of 22.35 years, who had not undergone orthodontic treatment were studied. The subjects were divided into two groups: group I, 20 radiographs of subjects without, and group II, 20 radiographs of subjects with mandibular third molars. The mean values of the groups were compared using a Student's t-test. The results show that, in both groups, the mandibular premolars and molars had enhanced angulation in the mesial direction, when compared with a control group of 42 Caucasians ranging in age from 12 to 17 years with a 'normal' occlusion (P < 0.05), while the mesiodistal axial angulation of the mandibular canines was similar to the control group (P < 0.05). The two groups, when compared, exhibited similar angular values for the canines, premolars and mandibular molars (P < 0.05), indicating no influence of the third molars.

The purpose of this study was to investigate the effect of treatment of mandibular crowding with self-ligating and conventional brackets on dental arch variables. Fifty-six patients were selected from a pool of subjects satisfying the following inclusion criteria: non-extraction treatment in the mandibular or maxillary arches, eruption of all mandibular teeth, no spaces and an irregularity index greater than 2 mm in the mandibular arch, and no adjunct treatment such as etxra- or intraoral appliances. The patients were assigned to two groups: one group received treatment with the self-ligating bracket and the other with a conventional edgewise appliance, both with a 0.022 inch slot. Lateral cephalometric radiographs obtained at the beginning (T1) and end (T2) of treatment were used to assess the alteration in mandibular incisor inclination, and measurements of intercanine and intermolar widths were made on dental casts to investigate changes associated with the correction. The results were analysed with bivariate and multivariate linear regression analysis in order to examine the effect of the bracket systems on arch width or lower incisor inclination, adjusting for the confounding effect of demographic and clinical characteristics. An alignment-induced increase in the proclination of the mandibular incisors was observed for both groups; no difference was identified between self-ligating and conventional brackets with respect to this parameter. Likewise, an increase in intercanine and intermolar widths was noted for both bracket groups; the self-ligating group showed a higher intermolar width increase than the conventional group, whereas the amount of crowding and Angle classification were not significant predictors of post-treatment intermolar width.

The aims of this study were to identify possible gender-related differences in tooth size ratios, to determine whether there is a prevalence for intermaxillary tooth size discrepancies in any malocclusion group, and to detect the percentage of tooth size discrepancies outside 1 or 2 standard deviations (SDs) from Bolton's mean. The material comprised the models of 500 subjects (284 females and 216 male aged between 12 and 28 years). Five groups were formed: normal occlusion, Class I, Class II division 1, Class II division 2, and Class III, which had an equal number of subjects. Tooth size measurements were undertaken using an electronic measuring device. Overall, anterior, and posterior ratios were computed as described by Bolton. For statistical evaluation, analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) tests were used. A significant gender difference was found only for posterior ratio in all groups (P < 0.01). There was no significant difference among the malocclusion groups in anterior ratio, but the differences for overall and posterior ratios were significant (P < 0.05 and P < 0.001, respectively). A large number of subjects had discrepancies greater than 2 SD from Bolton's mean. In addition, the means and SDs in this investigation were found to be larger than those of Bolton. Intermaxillary tooth size ratios may vary in different malocclusion types and may, to some degree, contribute to the severity of a malocclusion.

The aim of this study was to determine the occurrence of oral health impacts among patients with severe malocclusions and dentofacial deformities before treatment. A further aim was to evaluate the effect of gender or the type of malocclusion on the oral impacts. The study comprised 151 adult patients who were referred for orthodontic or surgical-orthodontic treatment to the Oral and Maxillofacial Department, Oulu University Hospital, Finland during the years 2001-2004. The study group consisted of 92 females and 59 males with a mean age of 35.5 years [standard deviation (SD) 11.5 years, range 16-64 years]. A self-completed Oral Health Impact Profile (OHIP)-14 questionnaire was used to measure oral impacts during a 1 month reference period. The prevalence, extent, and severity scores were calculated from the OHIP-14. Malocclusions were registered at clinical examination. The prevalence and mean extent and severity scores were compared among malocclusion groups and between genders. Statistical significance was evaluated with Mann-Whitney, Kruskall-Wallis, Chi-squared, and Fisher's exact tests. The prevalence of oral impacts perceived fairly or very often was 70.2 per cent. The mean severity and extent scores were 17.2 (SD 10.5, range 0-45) and 2.5 (SD 2.6, range 0-10), respectively. Physical pain as well as psychological discomfort and disability were the most commonly perceived oral impacts. Being self-conscious, feeling tense, having difficulties in relaxing, and being somewhat irritable with other people were more common in females than in males. No differences were observed in oral impacts among the malocclusion groups. Compared with a 'normal' population, patients with severe malocclusions report high levels of oral impacts. Females reported oral impacts more often than males.

Although there have been some reports on the relationship between craniofacial morphology and the activity of the temporal muscle attached to the coronoid process, such relationship is still unclear. The aim of the present study was therefore to investigate the relationship between the coronoid process and overall craniofacial morphology using lateral cephalograms of 60 female subjects (mean age 9.6 years) without mandibular deviation. Statistical testing was undertaken using stepwise regression analysis. Anterior coronoid marginal depth correlated negatively (r = 0.71) with gonial angle, SNA, and overjet. The coronoid angle also correlated negatively (r = 0.86) with both the vertical and horizontal lengths from sella to the coronoid tip as well as with the horizontal length from sella to the posterior ramus margin. Furthermore, the coronoid length correlated positively (r = 0.61) with the coronoid angle and the anterior coronoid marginal depth. The coronoid width was also positively (r = 0.69) correlated with overbite. Coronoid process morphology is related not only to mandibular morphology and position but also to maxillary position and the dental relationship in the anterior region. It therefore seems clear that coronoid process morphology might be related to temporal muscle functioning and its associated craniofacial morphological measurements.

The purpose of this study was to quantitatively evaluate skeletal and dental compensation in patients with vertical skeletal dysplasias and to determine which dentoalveolar parameters compensate for vertical jaw discrepancies. Cephalometric analyses were performed on pre-treatment lateral cephalographs of 186 orthodontic patients (120 females and 66 males; mean age 15 years 11 months) who met the selection criteria. SN-MP angle was used to classify the facial patterns as: hyperdivergent > 36 degrees, normo = 28-36 degrees, and hypo < 28 degrees. Analysis of variance (ANOVA) was used to determine statistical differences between the means in the three vertical facial types. To evaluate dental compensation quantitatively, correlation analyses were performed to find associations between skeletal and dental parameters. To further elucidate the compensatory nature of the lower incisors, regression analyses and scattergrams were obtained, with SN-MP as a measure of the vertical skeletal discrepancy. ANOVA showed statistically significant differences for most of the skeletal variables, but only for lower incisor height and inclination among the dentoalveolar parameters. Correlation analyses demonstrated significant relationships between various skeletal variables. LI-MP showed a negative relationship with SN-MP, whereas LAMdH demonstrated a positive linear relationship with SN-MP. Among all dentoalveolar heights, UAMxH showed the weakest, and LAMdH the strongest, associations with skeletal parameters. The variability in dentoalveolar compensation therefore demands individualized diagnosis and treatment planning. LAMdH and LI-MP parameters were the most likely, whereas UAMxH was the least likely parameter to compensate for vertical dysplasia.

The aim of this study was to investigate a method which minimizes the effects of geometric distortion on various cephalometric measurements used to determine sagittal discrepancy, such as ANB angle, Wits appraisal, AB plane angle, projections on the palatal plane, Frankfort horizontal (FH) plane, the mandibulomaxillary bisector, and the SN line, in an attempt to optimize the correlation between them. This was accomplished by superimposing the Bolton 12-year male-female averaged template on a patient's tracing using Procrustes analysis and performing measurements while exchanging the patient's reference landmarks/planes (point N, the mandibulomaxillary bisector, FH plane, occlusal plane, palatal plane, and SN line) with those of the template. The normalized measurements were then compared with their classic counterparts using correlation coefficients. The above cephalometric analyses, classic and normalized, were applied to 71 patients [26 males: mean age 13.1 years, standard deviation (SD) 1.1 years and 45 females: mean age of 14.6 years, SD 8.2 years]. Spearman's rank correlation coefficient was calculated between the classic measurements and their normalized counterparts, resulting in a consistent increase in the correlation between the normalized measurements in comparison with the classic ones. This increase varied in absolute value from 0.052 to 0.405. All normalized measurements were highly correlated (P > 0.742, absolute value). Although correlation calculations do not represent a true measure of diagnostic performance, it is hoped that improving their correspondence heightens the possibility of the different tests agreeing on the patient's sagittal discrepancy, decreasing the possibility of differing, or even totally opposing diagnostic outcomes resulting from their application to (clear-cut) Class I, II, and III patients.

The aim of this study was to investigate if true incisor intrusion can be achieved using miniscrews. Eleven patients (three males and eight females; mean age: 19.8 +/- 4.8 years) with normal vertical dimension showing a pre-treatment deep bite of 5.9 +/- 0.9 mm and a 'gummy' smile were enrolled in the study. After levelling of the maxillary central and lateral incisors with a segmental arch, an intrusive force of 80 g using closed coil springs was applied from two miniscrews placed between the roots of the lateral and canine teeth. The amount of incisor intrusion was evaluated on lateral cephalometric headfilms taken at the end of levelling (T1) and at the end of intrusion (T2). Statistical analysis of the data was performed using a paired t and Wilcoxon signed rank tests. A significance level of P < 0.05 was predetermined. The mean upper incisor intrusion was 1.92 mm and the mean overbite decrease 2.25 +/- 1.73 mm in 4.55 months. Upper incisor angulation resulted in a 1.81 +/- 3.84 degree change in U1-PP angle and a 1.22 +/- 3.64 degree change in U1-NA angle. However, these were not statistically significant (P > 0.05). True intrusion can be achieved by application of intrusive forces close to the centre of resistance using miniscrews. However, studies with a larger number of subjects and long-term follow-up are necessary.

The aim of the present study was to determine the dental and occlusal features that could contribute to the aetiology of palatally displaced canines (PDCs). The material consisted of pre-treatment dental casts of 50 patients (36 females and 14 males) with unilateral and bilateral PDCs aged 14-16 years (mean 15.6 +/- 1.6 years). These were compared with a control group of 50 treated subjects (25 males and 25 females) of the same age with normally erupted maxillary canines. The following parameters were measured on the dental casts: the mesiodistal (MD) and buccolingual (BL) width of each maxillary tooth, the maxillary interpremolar and intermolar widths, overjet and overbite, dentoalveolar arch relationship (based on incisor classification), and missing or anomalous teeth. The differences between the PDC group and controls were determined using a Student's t-test. P values less than 0.05 were considered significant. PDCs occurred most frequently in subjects with a Class I occlusion. Sixteen per cent of the PDC subjects had congenital absence or peg-shaped lateral incisors or congenital absence of the second premolar, demonstrating a clear association between palatal impaction of the maxillary canine and anomalous or congenital tooth absence. The overjet was significantly smaller in the PDC female subjects, especially in those with unilateral impaction (P < 0.05). Overbite was significantly greater in PDC male subjects compared with the controls, especially in bilateral impaction cases. There was no statistically significant difference between the groups with regard to the maxillary transverse dimensions, maxillary MD widths, or palatal height for either gender.

The aim of this study was to compare the accuracy of cephalometric measurements made with digital tracing software (FACAD) with equivalent hand-traced measurements, and to evaluate the reproducibility of each method. Pre- and post-surgical lateral cephalographs of 30 adult patients (12 males and 18 females, median age = 25 years, standard deviation = 8.7) who had undergone orthognathic treatment were scanned into a computer. One operator identified 25 landmarks digitally on the computer display and manually on acetate paper. Measurements on the 60 radiographs were duplicated, and measurement error of each method was determined with interclass correlation. A paired t-test was used to detect differences between the manual and digital methods. Overall, greater variability in digital cephalometric measurements was found. Differences in Gn', Li, Si, and Ii-Li measurements between the two methods were statistically (P < 0.05), but not clinically significant. The findings indicate that the results of the two investigated tracing methods are similar and that digital tracing with FACAD is reliable and can be used routinely.

There is a clearly established relationship between masticatory muscle structure and facial form. Human studies in this area, however, have been limited, especially in consideration of the myosin heavy chain (MyHC) family of contractile proteins. The aim of this pilot study was to assess if differences were detectable between genotype with respect to MyHC isoforms and the vertical facial phenotype in a sample of nine Caucasian female patients, age range 18-49 years, using a novel rapid technique. Masseter muscle biopsies were taken from patients with a range of vertical facial form. The levels of expression of the MyHC isoform genes MYH 1, 2, 3, 6, 7, and 8 were compared with the expression in a female calibrator patient aged 23 years with normal vertical facial form, using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Statistical analysis was undertaken using Pearson correlation coefficient. The results showed that there were distinct differences in gene expression between patients with a wide range of variation although changes in MYH1 were consistent with one cephalometric variable, the maxillo-mandibular angle. The full procedure, from start to finish, can be completed within half a day. Rapid genotyping of patients in this way could reveal important information of relevance to treatment. This technology has potential as a diagnostic and prognostic aid when considering correction of certain malocclusions.