IMU Sensors Measurements Towards the Development of Novel Prosthetic Arm Control Strategies.

The complexity of the human upper limb makes replicating it in a prosthetic device a significant challenge. With advancements in mechatronic developments involving the addition of a large number of degrees of freedom, novel control strategies are required. To accommodate this need, this study aims at developing an IMU-based control for the HannesARM upper-limb prosthetic device, as a proof-of-concept for new control strategies integrating data-fusion approaches. The natural human control of the upper-limb is based on different inputs that allow adaptive control. To mimic this in prostheses, the implementation of IMUs provides kinematic information of both the stump and the prosthesis to enrich the EMG control. The principle of operation is to decode upper limb movements by using a custom-made system and to replicate them in prosthetic arms improving the control algorithms. To evaluate the system's effectiveness, the custom algorithm's motion extraction was compared to a motion capture system using fifteen able-bodied subjects. The results showed that this system scored 0.16 ± 0.04 and 0.81 ± 0.12 in Root Mean Squared Error and Cross-Correlation compared to the motion capture system. Experimental results demonstrate how this work can extract valuable kinematic information necessary for new and improved control strategies, such as intention detection or pattern recognition, to allow users to perform a broader range of tasks and enhancing in turn their quality of life.

Preliminary Assessment of Two Simultaneous and Proportional Myocontrol Methods for 3-DoFs Prostheses Using Incremental Learning.

Despite progressive developments over the last decades, current upper limb prostheses still lack a suitable control able to fully restore the functionalities of the lost arm. Traditional control approaches for prostheses fail when simultaneously actuating multiple Degrees of Freedom (DoFs), thus limiting their usability in daily-life scenarios. Machine learning, on the one hand, offers a solution to this issue through a promising approach for decoding user intentions but fails when input signals change. Incremental learning, on the other hand, reduces sources of error by quickly updating the model on new data rather than training the control model from scratch. In this study, we present an initial evaluation of a position and a velocity control strategy for simultaneous and proportional control over 3-DoFs based on incremental learning. The proposed controls are tested using a virtual Hannes prosthesis on two healthy participants. The performances are evaluated over eight sessions by performing the Target Achievement Control test and administering SUS and NASA-TLX questionnaires. Overall, this preliminary study demonstrates that both control strategies are promising approaches for prosthetic control, offering the potential to improve the usability of prostheses for individuals with limb loss. Further research extended to a wider population of both healthy subjects and amputees will be essential to thoroughly assess these control paradigms.

A Novel Method for Vibrotactile Proprioceptive Feedback Using Spatial Encoding and Gaussian Interpolation.

OBJECTIVE: The bidirectional communication between the user and the prosthesis is an important requirement when developing prosthetic hands. Proprioceptive feedback is fundamental to perceiving prosthesis movement without the need for constant visual attention. We propose a novel solution to encode wrist rotation using a vibromotor array and Gaussian interpolation of vibration intensity. The approach generates tactile sensation that smoothly rotates around the forearm congruently with prosthetic wrist rotation. The performance of this scheme was systematically assessed for a range of parameter values (number of motors and Gaussian standard deviation). METHODS: Fifteen non-disabled subjects and one individual with congenital limb deficiency used vibrational feedback to control a virtual hand in the target-achievement control test. Performance was assessed by end-point error and efficiency as well as subjective impressions. RESULTS: The results showed a preference for smooth feedback and a higher number of motors (8 and 6 versus 4). With 8 and 6 motors, the standard deviation, determining the sensation spread and continuity, could be modulated through a broad range of values (0.1 - 2) without a significant performance loss. The overall average error and efficiency across these feedback configurations were ∼ 10% and ∼ 30%, respectively. For low values of standard deviation (0.1-0.5), the number of motors could be reduced to 4 without a significant performance decrease. CONCLUSION: The study demonstrated that the developed strategy provided meaningful rotation feedback. Moreover, the results indicate that the Gaussian standard deviation could be used as an independent parameter to encode an additional feedback variable. SIGNIFICANCE: The proposed method is a flexible and effective approach to provide proprioceptive feedback while adjusting the trade-off between sensation quality and the number of vibromotors.

Object stiffness recognition and vibratory feedback without ad-hoc sensing on the Hannes prosthesis: A machine learning approach.

Introduction: In recent years, hand prostheses achieved relevant improvements in term of both motor and functional recovery. However, the rate of devices abandonment, also due to their poor embodiment, is still high. The embodiment defines the integration of an external object - in this case a prosthetic device - into the body scheme of an individual. One of the limiting factors causing lack of embodiment is the absence of a direct interaction between user and environment. Many studies focused on the extraction of tactile information via custom electronic skin technologies coupled with dedicated haptic feedback, though increasing the complexity of the prosthetic system. Contrary wise, this paper stems from the authors' preliminary works on multi-body prosthetic hand modeling and the identification of possible intrinsic information to assess object stiffness during interaction. Methods: Based on these initial findings, this work presents the design, implementation and clinical validation of a novel real-time stiffness detection strategy, without ad-hoc sensing, based on a Non-linear Logistic Regression (NLR) classifier. This exploits the minimum grasp information available from an under-sensorized and under-actuated myoelectric prosthetic hand, Hannes. The NLR algorithm takes as input motor-side current, encoder position, and reference position of the hand and provides as output a classification of the grasped object (no-object, rigid object, and soft object). This information is then transmitted to the user via vibratory feedback to close the loop between user control and prosthesis interaction. This implementation was validated through a user study conducted both on able bodied subjects and amputees. Results: The classifier achieved excellent performance in terms of F1Score (94.93%). Further, the able-bodied subjects and amputees were able to successfully detect the objects' stiffness with a F1Score of 94.08% and 86.41%, respectively, by using our proposed feedback strategy. This strategy allowed amputees to quickly recognize the objects' stiffness (response time of 2.82 s), indicating high intuitiveness, and it was overall appreciated as demonstrated by the questionnaire. Furthermore, an embodiment improvement was also obtained as highlighted by the proprioceptive drift toward the prosthesis (0.7 cm).

Benefits of the Cybathlon 2020 experience for a prosthetic hand user: a case study on the Hannes system.

BACKGROUND: Cybathlon championship aims at promoting the development of prosthetic and assistive devices capable to meet users' needs. This paper describes and analyses possible exploitation outcomes of our team's (REHAB TECH) experience into the Powered Arm Prosthesis Race of the Cybathlon 2020 Global Edition, with the novel prosthetic system Hannes. In detail, we present our analysis on a concurrent evaluation conducted to verify if the Cybathlon training and competition positively influenced pilot's performance and human-technology integration with Hannes, with respect to a non-runner Hannes user. METHODS: Two transradial amputees were recruited as pilots (Pilot 1 and Pilot 2) for the Cybathlon competition and were given the polyarticulated myoelectric prosthetic hand Hannes. Due to COVID-19 emergency, only Pilot 1 was trained for the race. However, both pilots kept Hannes for Home Use for seven weeks. Before this period, they both participated to the evaluation of functionality, embodiment, and user experience (UX) related to Hannes, which they repeated at the end of the Home Use and right after the competition. We analysed Pilot 1's training and race outcomes, as well as changes in the concurrent evaluation, and compared these results with Pilot 2's ones. RESULTS: The Cybathlon training gradually improved Pilot 1's performances, leading to the sixth place with a single error in task 5. In the parallel evaluation, both pilots had an overall improvement over time, whereas Pilot 2 experienced a deterioration of embodiment. In detail, Pilot 1, who followed the training and raced the Cybathlon, improved in greater way. CONCLUSION: Hannes demonstrated to be a valuable competitor and to perform grasps with human-like behaviors. The higher improvements of Pilot 1, who actively participated in the Cybathlon, in terms of functionality, embodiment and UX, may depend on his training and engagement in the effort of achieving a successful user-prosthesis interaction during the competition. Tasks based on Cybathlon's ones could improve the training phase of a prosthetic user, stimulating dexterity, prosthetic integration, and user perception towards the prosthesis. Likewise, timed races or competitions could facilitate and accelerate the learning phase, improving the efficiency and efficacy of the process.

Exploring the Embodiment of a Virtual Hand in a Spatially Augmented Respiratory Biofeedback Setting.

Enhancing the embodiment of artificial limbs-the individuals' feeling that a virtual or robotic limb is integrated in their own body scheme-is an impactful strategy for improving prosthetic technology acceptance and human-machine interaction. Most studies so far focused on visuo-tactile strategies to empower the embodiment processes. However, novel approaches could emerge from self-regulation techniques able to change the psychophysiological conditions of an individual. Accordingly, this pilot study investigates the effects of a self-regulated breathing exercise on the processes of body ownership underlying the embodiment of a virtual right hand within a Spatially Augmented Respiratory Biofeedback (SARB) setting. This investigation also aims at evaluating the feasibility of the breathing exercise enabled by a low-cost SARB implementation designed for upcoming remote studies (a need emerged during the COVID-19 pandemic). Twenty-two subjects without impairments, and two transradial prosthesis users for a preparatory test, were asked (in each condition of a within-group design) to maintain a normal (about 14 breaths/min) or slow (about 6 breaths/min) respiratory rate to keep a static virtual right hand "visible" on a screen. Meanwhile, a computer-generated sphere moved from left to right toward the virtual hand during each trial (1 min) of 16. If the participant's breathing rate was within the target (slow or normal) range, a visuo-tactile event was triggered by the sphere passing under the virtual hand (the subjects observed it shaking while they perceived a vibratory feedback generated by a smartphone). Our results-mainly based on questionnaire scores and proprioceptive drift-highlight that the slow breathing condition induced higher embodiment than the normal one. This preliminary study reveals the feasibility and potential of a novel psychophysiological training strategy to enhance the embodiment of artificial limbs. Future studies are needed to further investigate mechanisms, efficacy and generalizability of the SARB techniques in training a bionic limb embodiment.

Dental anomalies in the primary dentition and their repetition in the permanent dentition: a diagnostic performance study.

This study investigated the recurrence in the permanent dentition of dental anomalies of the primary dentition. A sample of 189 subjects (100 males, 89 females, mean age of 5 years and 7 months) with anomalies of primary teeth (tooth hypodontia, supernumerary teeth, geminated teeth, and fused teeth) was selected and re-analyzed at a mean age of 11 years and 2 months for the recurrence of the dental anomalies in the permanent dentition. As a control group, 271 subjects (123 males, 148 females) without dental anomalies in the primary dentition were selected. The recurrence in the permanent dentition of the dental anomalies in the primary dentition was evaluated by measures of diagnostic performance. The results showed high values for the repetition of hypodontia (positive likelihood ratio = 102.0); low score for the repetition of hyperdontia (positive likelihood ratio = 6.5); low positive likelihood ratio (9.1) for gemination of primary teeth resulting in supernumerary permanent teeth; high positive likelihood ratio (47.0) for fusion of primary teeth followed by missing permanent teeth. Dental anomalies in the primary dentition are associated with an increased likelihood of anomalies of the succedaneous permanent.

Oral and craniofacial findings of Binder syndrome: two case reports.

Binder syndrome is a malformative midfacial alteration, known also as maxillonasal dysplasia or maxillonasal dysostosis. In this article, two cases of affected patients are reported, and the features of the condition are reviewed. One case presents a cleft lip. Hypotheses about etiology, pathogenesis, and classification of the syndrome are illustrated. This work provides a contribution for the delineation of a differential diagnostic procedure.

Transverse dimensions of dental arches in subjects with Class II malocclusion in the early mixed dentition.

OBJECTIVE: The purpose of this study was to analyze the transverse dentoalveolar features of subjects with Class II Division 1 malocclusion in mixed dentition when compared to subjects with normal occlusion. MATERIALS AND METHODS: The study was performed on 192 randomly selected subjects in the early mixed dentition. According to sagittal skeletal and occlusal features the sample was divided into two groups: 88 subjects (53 females and 35 males) with Class II skeletal disharmony and Class II, division 1 malocclusion (Class II Group, mean age 8 years and 10 months±11 months) and 104 subjects (66 females e 38 males) with dentoskeletal Class I relationships (Class I Group, mean age 9±1 years). The Class II group was further divided into two subgroups (maxillary protrusion group and mandibular retrusion group) on the basis of the skeletal characteristics. Intermolar and intercanine distances were measured on dental casts in both arches and posterior and anterior transversal discrepancy (PTID and ATID) were calculated. RESULTS: Subjects with Class II malocclusion showed a significantly greater negative PTID (-2.1 mm) which was associated with a significantly reduced maxillary width with respect to the Class I group (-2.2 mm). The Class II group showed also a significantly greater negative ATID (-1.4 mm) when compared to the Class I group. Subjects with mandibular retrusion showed a significantly greater reduction both in the maxillary intercanine width (-1.7 mm). and in the maxillary intermolar width (-2.7 mm) with respect to the Class I group. Subjects with maxillary protrusion presented with a significantly greater constriction at the maxillary intermolar width (-1.7 mm) when compared to the Class I group. CONCLUSIONS: Class II malocclusion with mandibular retrusion is associated with a significant constriction of the maxillary arch with reduced intercanine and intermolar widths. When Class II malocclusion is due to a maxillary protrusion the constriction at the maxillary arch is limited to the intermolar width.

Maxillary dental anomalies in children with cleft lip and palate: a controlled study.

OBJECTIVE: To evaluate the prevalence of dental abnormalities of the primary and permanent maxillary dentitions in children affected by unilateral (UCLP) and bilateral (BCLP) cleft of the lip and palate. METHODS: One hundred and fifty-six Caucasian patients (64 females and 92 males) affected by non-syndromic UCLP or BLCP were selected. A control sample of 1000 subjects (482 males and 518 females) without CLP was selected. All comparisons were carried out by means of z-tests on proportions. RESULTS: The prevalence rate for missing primary lateral incisors in UCLP subjects was 8.1% and it was 27.9% for the permanent lateral incisors. In BLCP subjects, the prevalence rates were 17% for the primary lateral incisors and 60% for the permanent lateral incisors. The second premolar was absent in 5.4% of UCLP subjects and in 8.8% in the BCLP sample. The statistical analysis revealed significant differences for the prevalence rates of all dental anomalies compared with the control group except for second premolar agenesis. CONCLUSIONS: In both UCLP and BCLP subjects the most prevalent missing teeth were the lateral incisors. The dental anomalies occurred predominantly in the cleft area, thus suggesting that the effect of the cleft disturbance is more local than general on the dentition.

Morphometric investigation in the skulls of young adults. A comparative study between 19th century and modern Italian samples.

OBJECTIVE: To test the hypothesis that there are no differences in the shape of the cranial complex between two samples from the same restricted geographical area and separated by almost 150 years. MATERIALS AND METHODS: A group of 35 skulls from the 19th century were selected and compared with a modern sample composed of 43 young adult subjects by means of lateral cephalograms and using a morphometric analysis. The peculiarity of this work is the uniformity of the two samples involving adults coming from the same restricted birthplace and with homogeneity for the orthodontic classification. RESULTS: Although the time spans are short, significant differences were found between the two samples. Shape changes included maxillary elongation toward the posterior region and a marked change in shape configuration in the mandible's points that shows a posterior rotation of the mandibular body. The global result of this cranial base point's movements symbolizes a tiny tendency toward closure of the cranial base angle. CONCLUSIONS: The hypothesis is rejected. Changes were evident, and environmental influences can be responsible for these changes.

Dentoskeletal effects of a removable appliance for expansion of the maxillary arch: a postero-anterior cephalometric study.

The aim of this study was to evaluate the dentoskeletal effects of early treatment in the primary or early mixed dentition with a removable appliance with expansion springs, assessed on postero-anterior (PA) cephalograms, in patients with a unilateral posterior crossbite when compared with untreated subjects. The treatment group consisted of 23 subjects, 8 males, and 15 females treated with a removable appliance for the expansion of the maxillary arch. The mean age at the start of expansion (T1) was 6 years 2 +/- 17 months, and 8 years +/- 18 months at the end of active therapy and after 1 year of retention (T2), with an observation interval of 22 +/- 7 months. The control group comprised 20 subjects (9 males and 11 females) with an untreated unilateral posterior crossbite. Their mean age was 5 years 9 +/- 15 months at the first observation and 7 years and 4 +/- 16 months at the second examination. The interval between the two observations was 18 +/- 7 months. Nine skeletal and two dental measurements on the transverse plane were assessed. The data from the two groups were compared by means of a Student's t-test for independent samples (P < 0.05). Positive dental and skeletal effects induced by the therapy were observed at T2. The width of the upper dental arch and that of the skeletal maxillary transverse dimension were significantly greater (P < 0.001) in the treatment group when compared with the controls.

Early orthodontic treatment of skeletal open-bite malocclusion with the open-bite bionator: a cephalometric study.

INTRODUCTION: This study was designed to evaluate the effectiveness of the open-bite bionator in growing subjects with increased vertical dimensions. METHODS: The records of 20 subjects with high-angle skeletal relationships (MPA > or =25 degrees) were examined. Cephalometric measurements were compared with those obtained from 23 sets of records of an untreated group matched according to age, sex, vertical skeletal relationships, and time intervals between records. Lateral cephalograms were analyzed before the start of treatment (mean age; 8.3 years) and after therapy and retention, with a mean period of observation of 2.5 years. RESULTS: The treated group had a significantly smaller palatal plane-mandibular plane angle (-1.9 degrees) and a greater overbite (+1.5 mm) associated with a significantly smaller overjet when compared with the control group. CONCLUSIONS: Based on the analysis of this sample, early treatment of skeletal open bite with the open-bite bionator appears to produce a modest effect that mainly consists of significant improvement in intermaxillary divergence. No favorable effects on the extrusion of posterior teeth were found.

Dentoalveolar effects induced by a removable expansion plate.

OBJECTIVE: The aim of this article was to analyze the changes in the transverse dimensions of the dental arches produced by a removable expansion plate (Removable Spring Expander, RSE) in subjects with unilateral posterior crossbite. MATERIALS AND METHODS: The treated group (TG) comprised of 17 subjects (5 males and 12 female) with unilateral posterior crossbites. Dental casts were available at pre-treatment (T1) and at a post-retention observation period (T2). The mean age at T1 was 6 years +/- 1 year and 4 months, and 7 years 11 months +/- 1 year and 5 months at T2. Seventeen subjects (7 males, 10 females) with an untreated unilateral posterior crossbite were used as the control group (CG). The mean age was 5 years 11 months +/- 1 year and 2 months at T1 and 7 years 9 months +/- 1 year and 4 months at T2. Post-retention changes in the transverse dimensions of the dental arches were evaluated statistically by means of a t-test for independent samples. RESULTS: The TG showed statistically significant increments when compared with untreated controls in maxillary intermolar widths (4.5 mm), intercanine widths (3.6 mm), and there were significant improvements in the posterior transverse interarch discrepancy (4.2 mm) and in the anterior transverse interarch discrepancy (3.3 mm). No statistically significant differences were found for the mandibular intermolar and intercanine widths between TG and CG. CONCLUSIONS: The expansion plate is a simple and effective device for the expansion of the upper arch in the deciduous and early mixed dentitions.

Dental arch dimensions in the mixed dentition: a study of Italian children born in the 1950s and the 1990s.

The objective of this study was to compare the dental arch dimensions in the mixed dentition in two modern samples living in the same geographic area and separated by almost 35 years. A group of 83 subjects (39 boys and 44 girls) born between 1953 and 1959 (mean age: eight years and three months +/-15 months for the boys and seven years and 11 months +/-12 months for the girls) were compared with a group of 84 subjects (38 boys and 46 girls) born between 1990 and 1998 (mean age: eight years and eight months +/-12 months for the boys and eight years and four months +/-11 months for the girls). Measurements were taken on dental casts for posterior and anterior arch segments, intermolar and intercanine width, and mesiodistal size of incisors. The available anterior space in both arches and the posterior and anterior transverse dimensions were calculated. Groups were compared using a nonparametric test (Mann-Whitney U-test) for independent samples (P < .05). Results show that both boys and girls of 1990s showed significantly smaller maxillary intermolar width when compared with 1950s. Posterior transverse interarch discrepancy was significantly minor in girls of 1990s. The present population has a greater probability of developing a malocclusion as a consequence of the secular trend toward the reduction of the width of the upper arch.

Tooth wear in the mixed dentition: a comparative study between children born in the 1950s and the 1990s.

The aim of this study was to evaluate the degree of tooth wear in posterior deciduous teeth of 100 subjects in the second phase of mixed dentition who were born in the 1950s (50sG) and 100 subjects born in the 1990s (90sG). The degree of abrasion for each posterior deciduous tooth was scored ranging from 0 to 3. The comparison of the degree of abrasion showed significant differences between the two groups for all examined teeth (upper and lower deciduous canines and first and second primary molars) all of which appeared to be more abraded in the 50sG. The findings of the present study indicate that subjects who were born in the 1950s exhibited a significantly greater degree of tooth wear on the posterior deciduous teeth when compared with contemporary subjects, along with a well-recognized lower prevalence of malocclusions. Changes in dietary habits and a diet based on processed foods may be postulated as factors involved with a decrease of dental attrition in contemporary populations. An increase in the prevalence of mouth breathing (tested in the present study) appears to be associated with a decrease in tooth wear in the contemporary population as well.

Abnormal mandibular growth after craniovertebral surgery in Morquio syndrome type A.

Morquio syndrome or MPS4A is an autosomal recessive inherited metabolic disease, due to a deficiency of N-acetil-galactosamine-6-sulfatase (OMIM 253000). Hypoplastic odontoid processes causing atlantoaxial subluxation and cervical myelopathy are usual clinical findings. Surgical intervention of craniocervical fusion is often performed to prevent this complication. Clinical and cephalometric findings in a patient affected by Morquio syndrome after craniovertebral surgery are described. Facial growth pattern in the lateral plane changed dramatically. The mandibular gonial angle (ArGoMe), the body of the mandible (GoGn), and the total length of the mandible (CoGn) increased abnormally, whereas the mandibular ramus (CoGo) exhibited normal growth. Knowledge of the possibility of abnormal mandibular growth may contribute in long-term orthodontic management of such subjects.

Class II malocclusion with maxillary protrusion from the deciduous through the mixed dentition: a longitudinal study.

The aim of this study was to analyze the skeletal characteristics of Class II malocclusion with maxillary protrusion in the deciduous dentition and to describe the growth features of this type of skeletal imbalance during the transition from the deciduous through the mixed dentition. A group of 17 subjects having skeletal Class II malocclusions in the deciduous dentition due to maxillary protrusion was compared with a control group of 30 untreated subjects with ideal occlusion at the same stage of development. Both groups were observed for the first time in the deciduous dentition (T(1)) and followed during the transition from the deciduous to the mixed dentition (T(2)). During this time no orthodontic treatment was provided. Lateral cephalograms were taken for all subjects at T(1) and T(2). A cephalometric analysis was performed based on a reference system that consisted of two perpendicular lines traced through stable basicranical structures. The results indicate that a Class II skeletal pattern due to a maxillary protrusion is established early in the deciduous dentition and remains unmodified in the transition to the mixed dentition. The maxilla appeared to be displaced forward in Class II subjects, whereas the mandibles of the Class I and Class II subjects did not show any significant differences at this stage of growth. In the passage from the deciduous through the mixed dentition, Class I and Class II subjects showed growth increments that were not significantly different from each other. Sucking habits appeared to be correlated with the skeletal maxillary protrusion.

Biometric and magnetic resonance imaging assessment of dentofacial abnormalities in a case of Klippel-Trénaunay-Weber syndrome.

Klippel-Trénaunay-Weber syndrome is characterized by cutaneous hemangioma, arteriovenous fistulas or varicosities (or both), and unilateral hypertrophy of hard and soft tissues with different localization. Klippel-Trénaunay-Weber syndrome represents a syndrome of interest for those in the fields of oral and maxillofacial radiology and pathology because of the high incidence of compromise of the orofacial area in affected patients. The patient reported here presents with all of the 3 characteristic signs of the syndrome. The somatic and facial hypertrophy is contralateral to angiomata. As revealed through the use of magnetic resonance imaging, the primary component of facial hypertrophy is adipic subcutaneous tissue. Statistical analysis of the dental dimensions revealed that teeth on the hypertrophic side are significantly larger than normal.

Morphometric analysis of the transverse dentoskeletal features of class II malocclusion in the mixed dentition.

The aim of the present study was to evaluate the dentoskeletal features of Class II malocclusion in the transverse plane by means of a morphometric analysis (thin-plate spline analysis [TPS]) applied to posteroanterior cephalograms. A sample of 49 subjects (24 males, 25 females; mean age 7 years, 9 +/- 5 months) with Class II Division 1 malocclusion was compared with a control group of 50 subjects (17 males, 33 females; mean age 8 years, 4 +/- 3 months) with Class I occlusion. Subjects of both groups were in the mixed dentition and had no history of orthodontic treatment. Average craniofacial configurations were subjected to TPS analysis to compare the differences in shape between the two groups. The results of the present study showed that subjects with Class II malocclusion exhibited significant shape differences in craniofacial configuration in the frontal plane when compared with subjects with normal occlusion; these differences mainly consisted of a contraction of the maxilla at both the skeletal and the dentoalveolar levels and a narrowing of the base of the nose. The reduction in maxillary dentoskeletal width was associated with an increase in the vertical height of the maxilla.