Three-dimensional Soft Tissue Research Articles

Physics-informed neural network estimation of material properties in soft tissue nonlinear biomechanical models

AbstractThe development of biophysical models for clinical applications is rapidly advancing in the research community, thanks to their predictive nature and their ability to assist the interpretation of clinical data. However, high-resolution and accurate multi-physics computational models are computationally expensive and their personalisation involves fine calibration of a large number of parameters, which may be space-dependent, challenging their clinical translation. In this work, we propose a new approach, which relies on the combination of physics-informed neural networks (PINNs) with three-dimensional soft tissue nonlinear biomechanical models, capable of reconstructing displacement fields and estimating heterogeneous patient-specific biophysical properties and secondary variables such as stresses and strains. The proposed learning algorithm encodes information from a limited amount of displacement and, in some cases, strain data, that can be routinely acquired in the clinical setting, and combines it with the physics of the problem, represented by a mathematical model based on partial differential equations, to regularise the problem and improve its convergence properties. Several benchmarks are presented to show the accuracy and robustness of the proposed method with respect to noise and model uncertainty and its great potential to enable the effective identification of patient-specific, heterogeneous physical properties, e.g. tissue stiffness properties. In particular, we demonstrate the capability of PINNs to detect the presence, location and severity of scar tissue, which is beneficial to develop personalised simulation models for disease diagnosis, especially for cardiac applications.

The Accuracy of Three-Dimensional Soft Tissue Simulation in Orthognathic Surgery-A Systematic Review.

Three-dimensional soft tissue simulation has become a popular tool in the process of virtual orthognathic surgery planning and patient-surgeon communication. To apply 3D soft tissue simulation software in routine clinical practice, both qualitative and quantitative validation of its accuracy are required. The objective of this study was to systematically review the literature on the accuracy of 3D soft tissue simulation in orthognathic surgery. The Web of Science, PubMed, Cochrane, and Embase databases were consulted for the literature search. The systematic review (SR) was conducted according to the PRISMA statement, and 40 articles fulfilled the inclusion and exclusion criteria. The Quadas-2 tool was used for the risk of bias assessment for selected studies. A mean error varying from 0.27 mm to 2.9 mm for 3D soft tissue simulations for the whole face was reported. In the studies evaluating 3D soft tissue simulation accuracy after a Le Fort I osteotomy only, the upper lip and paranasal regions were reported to have the largest error, while after an isolated bilateral sagittal split osteotomy, the largest error was reported for the lower lip and chin regions. In the studies evaluating simulation after bimaxillary osteotomy with or without genioplasty, the highest inaccuracy was reported at the level of the lips, predominantly the lower lip, chin, and, sometimes, the paranasal regions. Due to the variability in the study designs and analysis methods, a direct comparison was not possible. Therefore, based on the results of this SR, guidelines to systematize the workflow for evaluating the accuracy of 3D soft tissue simulations in orthognathic surgery in future studies are proposed.

Lower Third Soft Tissue Changes After Orthognathic Surgery.

Triple jaw surgery, inclusive of a LeFort osteotomy, bilateral sagittal split osteotomy, and genioplasty, is used to maximize functional and esthetic outcomes for patients. This is achieved through the procedure's measurable effects on the craniofacial skeleton but is also influenced by the soft tissue changes that occur as a result of the procedure. This study aims to characterize the three-dimensional (3D) soft tissue changes of triple jaw surgery. Patient demographics were collected along with pre and postoperative 3D images (3D VECTRA photosystem, Canfield, Fairfield, NJ). Orolabial anthropometric measurements were performed using Mirror (Canfield Scientific Inc., Fairfield, NJ). Forty-eight 3D data sets were included. The male/female ratio was 0.6, with a mean age of 23.4 years. Significant postoperative decreases (P<0.001) were seen in the mean absolute distance from the lower lip to S-line and distance from lower lip to H-line. In female patients, upper vermilion fullness, lower lip height, lower vermilion fullness, distance from lower lip to S-line, and absolute distance from lower lip to H-line were found to fall within ideal norms postoperatively. In male patients, lower lip height, lower vermilion fullness, distance from lower lip to S-line, and absolute distance from lower lip to H-line were found to fall within ideal norms postoperatively. Triple jaw surgery has a significant soft tissue impact and can transform some orolabial measurements to conform to ideal norms.

Three-dimensional soft tissue reconstruction and volume measurement used for the diagnosis of dysthyroid optic neuropathy.

Dysthyroid optic neuropathy (DON) leads to vision loss. This study aimed to investigate a new method that can directly evaluate the change in muscle cone inner volume (MCIV) and distinguish DON orbits from non-DONs. This study included 54 patients (108 orbits) who were diagnosed with thyroid eye disease and treated at the Beijing Tongren Hospital between December 2019 and September 2021. The extraocular muscle volume (EOMV), orbital fat volume (OFV), and bony orbit volume (BOV) of the patients were measured using three-dimensional reconstruction. MCIV was measured using artificially defined boundaries. The associations between these volumes and clinical indicators were studied, and the diagnostic efficacy of these volumes for DON was described using receiver operating characteristic (ROC) curves. The ROC curve showed that the area under the curve of MCIV/BOV (%) combined with EOMV/BOV (%) reached 0.862 (p < 0.001), with a sensitivity of 85.7% and a specificity of 76.1%. The combination of MCIV/BOV (%) and EOMV/BOV (%) is a good indicator for the diagnosis of DON, which aids in the early detection and intervention of DON.

Comparison of three-dimensional soft tissue changes according to the split pattern after sagittal split osteotomy in patients with skeletal class III malocclusion

ObjectivesThis study aimed to analyse the changes in soft tissue and hard tissue stability associated with the split pattern, i.e. long split (LS) or short split (SS), after sagittal split osteotomy.Materials and methodsPatients who underwent sagittal split ramus osteotomy were classified into LS or SS groups according to postoperative computed tomography images. They were examined via lateral cephalography and three-dimensional (3D) optical scanning before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Six standard angles (SNA, SNB, ANB, FMA, FMIA, and IMPA) were used as measures of hard tissue change. The two sets of 3D data were superimposed, and the volumetric differences were calculated as the soft tissue change. The areas evaluated were delimited by 10 × 20-mm rectangles in the frontal aspect and a 25 × 25-mm square in the lateral aspect.ResultsA total of 42 sides (26 patients) were analysed, including 20 (16 patients) in the SS group and 22 (16 patients) in the LS group. We found no significant differences in cephalographic angle or soft tissue changes in the frontal aspect between the SS and LS groups. We found significant differences in the subauricular region from T0–T1 (p = 0.02), T0–T2 (p = 0.03), and T0–T3 (p = 0.037) in terms of soft tissue changes in the lateral aspect. The volume increase associated with posterior mandibular movement was greater in the LS group.ConclusionsWe found that LS patients with mandibular prognathism exhibited increased subauricular volumes following mandibular setback.Clinical relevanceIt is essential to predict the postoperative facial profile before surgery. The split pattern after sagittal split osteotomy affects the postoperative profile of patients with mandibular prognathism.

Photon and Proton irradiation in Patient-derived, Three-Dimensional Soft Tissue Sarcoma Models

BackgroundDespite their heterogeneity, the current standard preoperative radiotherapy regimen for localized high-grade soft tissue sarcoma (STS) follows a one fits all approach for all STS subtypes. Sarcoma patient-derived three-dimensional cell culture models represent an innovative tool to overcome challenges in clinical research enabling reproducible subtype-specific research on STS. In this pilot study, we present our methodology and preliminary results using STS patient-derived 3D cell cultures that were exposed to different doses of photon and proton radiation. Our aim was: (i) to establish a reproducible method for irradiation of STS patient-derived 3D cell cultures and (ii) to explore the differences in tumor cell viability of two different STS subtypes exposed to increasing doses of photon and proton radiation at different time points.MethodsTwo patient-derived cell cultures of untreated localized high-grade STS (an undifferentiated pleomorphic sarcoma (UPS) and a pleomorphic liposarcoma (PLS)) were exposed to a single fraction of photon or proton irradiation using doses of 0 Gy (sham irradiation), 2 Gy, 4 Gy, 8 Gy and 16 Gy. Cell viability was measured and compared to sham irradiation at two different time points (four and eight days after irradiation).ResultsThe proportion of viable tumor cells four days after photon irradiation for UPS vs. PLS were significantly different with 85% vs. 65% (4 Gy), 80% vs. 50% (8 Gy) and 70% vs. 35% (16 Gy). Proton irradiation led to similar diverging viability curves between UPS vs. PLS four days after irradiation with 90% vs. 75% (4 Gy), 85% vs. 45% (8 Gy) and 80% vs. 35% (16 Gy). Photon and proton radiation displayed only minor differences in cell-killing properties within each cell culture (UPS and PLS). The cell-killing effect of radiation sustained at eight days after irradiation in both cell cultures.ConclusionsPronounced differences in radiosensitivity are evident among UPS and PLS 3D patient-derived sarcoma cell cultures which may reflect the clinical heterogeneity. Photon and proton radiation showed similar dose-dependent cell-killing effectiveness in both 3D cell cultures. Patient-derived 3D STS cell cultures may represent a valuable tool to enable translational studies towards individualized subtype-specific radiotherapy in patients with STS.

A longitudinal study of facial asymmetry in a normal birth cohort up to 6 years of age and the predisposing factors.

This prospective, population-based cohort study aimed to investigate the development of facial asymmetry up to 6 years of age using a three-dimensional (3D) soft tissue imaging method in a normal population. In addition, the study sought to identify potential predisposing factors to facial asymmetry. A total of 102 newborns were enrolled in the study at birth. 3D stereophotogrammetric images of the head and face were analysed at the ages of 12 months (T1), 3 years (T2), and 6 years (T3). The surface-based analysis involved the calculation of the average distance (mm) and the symmetry percentage (%) between the original and mirrored surfaces. For landmark-based analysis, the distance of facial landmarks to the facial midline was examined. The final analysis included 70 (68.6%) subjects. Surface-based analysis showed a significant improvement of facial symmetry from T1 to T3 in all facial areas. Landmark-based analysis showed that upper facial landmarks were located, on average, slightly on the left and lower facial landmarks slightly on the right in relation to the facial midline (P < 0.001). The size of the study population was limited. Facial posture may affect the reliability of the results, especially in younger children. Facial asymmetry is detectable in early childhood and tends to reduce with age in young children. The lower face deviates slightly to the right, and the upper face to the left in relation to the facial midline. Possible predisposing factors for facial asymmetry at the age of 6 years include deformational plagiocephaly, sleeping position, and previous facial asymmetry.

Three-dimensional soft tissue landmark detection with marching cube algorithm

Current method of analyzing three-dimensional soft tissue data, especially in the frontal view, is subjective and has poor reliability. To overcome this limitation, the present study aimed to introduce a new method of analyzing soft tissue data reconstructed by marching cube algorithm (Program S) and compare it with a commercially available program (Program A). Cone-beam computed tomography images of 42 patients were included. Two orthodontists digitized six landmarks (pronasale, columella, upper and lower lip, right and left cheek) twice using both programs in two-week intervals, and the reliability was compared. Furthermore, computer-calculated point (CC point) was developed to evaluate whether human error could be reduced. The results showed that the intra- and inter-examiner reliability of Program S (99.7–100% and 99.9–100%, respectively) were higher than that of Program A (64.0–99.9% and 76.1–99.9%, respectively). Moreover, the inter-examiner difference of coordinate values and distances for all six landmarks in Program S was lower than Program A. Lastly, CC point was provided as a consistent single point. Therefore, it was validated that this new methodology can increase the intra- and inter-examiner reliability of soft tissue landmark digitation and CC point can be used as a landmark to reduce human error.

Finite element analysis of lumbosacral soft tissue at sitting posture at desktop computer

ABSTRACT Aim: This study aims to numerically determine the biomechanical effect of von Mises stress, induced at different flexion angles of the spine while sitting at a desktop computer, on the soft tissues in the front and back of the lumbosacral region, as well as to contribute to determining the ideal sitting posture. Materials and Methods: Three-dimensional (3D) soft tissue models were created using Solidworks. Static structural analyses of the tissues were performed in ANSYS with the finite element method (FEM). Stress distribution and stress values occurring in the anterior and posterior sides of the lumbosacral region at 0, 15, 30, and 45 spine flexion angles were analyzed separately. The values of von Mises stress formed in the anterior and posterior soft tissues of the lumbosacral region gradually increased with the increase in the flexion angle. Furthermore, the stress values in the anterior and posterior soft tissues were compared with each other for the same spinal flexion angle. Results: The von Mises stress values were found to be higher in the posterior side only at 0 degrees, whereas at 15, 30, and 45 degrees, they were higher in the anterior side. As a result, the most suitable position for sitting at a computer was determined. Lower flexion angles of the spine, such as 0 and 15 degrees, create less stress on the anterior and posterior sides of the lumbosacral region. Conclusion: Sitting postures with a flexion angle of the spine higher than 0-15 degrees are not appropriate, and desktop users are not recommended to adopt such a posture. The results of the analysis could be used to better understand the effects of prolonged sitting on the lumbosacral area and to design interventions to reduce the risk of injury or discomfort.

Soft tissue changes with skeletal anchorage in comparison to conventional anchorage protocols in the treatment of bimaxillary proclination patients treated with premolar extraction : Asystematic review.

This review systematically evaluates the evidence related to comparisons between skeletal and conventional anchorage protocols in the treatment of bimaxillary proclination patients who underwent premolars extraction with respect to soft tissue profile changes, treatment duration and three-dimensional (3D) soft tissue changes. Electronic database search and hand search with no language limitations were conducted in the Cochrane Library, PubMed, Ovid, Web of Science, Scopus and ClinicalTrials.gov. The selection criteria were set to include studies with patients aged 13years and above requiring extractions of upper and lower first premolars to treat bimaxillary proclination with high anchorage demand. Risk of bias assessment was undertaken with Cochrane's Risk Of Bias tool 2.0 (ROB 2.0) for randomised controlled trials (RCTs) and ROBINS‑I tool for nonrandomised prospective studies. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach was used for quality assessment. Results were summarised qualitatively; no meta-analysis was conducted. Two RCTs and two nonrandomised prospective studies were included. According to the GRADE approach, there is low to very low quality of evidence that treatment using mini-implant anchorage may significantly change nasolabial angle, upper and lower lip procumbence, and facial convexity angle compared to treatment with conventional anchorage. Similarly, very low quality evidence exists showing no differences in treatment duration between treatments with skeletal or conventional anchorage. The overall existing evidence regarding the effect of anchorage protocols on soft tissue changes in patients with bimaxillary protrusion and premolar extraction treatment plans is of low quality. PROSPERO CRD42020216684.

Three-dimensional soft tissue changes after reduction malarplasty in female patients

The aim of this study was to determine the three-dimensional soft tissue changes after reduction malarplasty. Soft tissue changes relative to the amount of movement of the zygomatic bone were studied. Pre- and postoperative cone beam computed tomography images of 21 female patients were superimposed. The anterior-most point of the body osteotomy (point A), arch osteotomy site (point D), and points dividing line A–D into thirds (points B and C) were marked on lateral view images. The vertical distances from the midsagittal line to the centre of the zygomatic bone and the outer prominence of the soft tissue were measured on the coronal view of each image. The proportion of the change in soft tissue to that of the bone before and after surgery was calculated for each point. The relationship between body mass index and the soft tissue change ratio, and the differences in soft tissue changes at each point were analysed. Mean soft tissue changes for points A, B, C, and D were 53.43%, 66.66%, 63.67%, and 57.23%, respectively. The amount of soft tissue change at point B was greater than that at points A and D, which were osteotomy sites. There was no statistical correlation between body mass index and the soft tissue change ratio at each point.

Three-dimensional evaluation of soft tissues in hyperdivergent skeletal class II females in Guangdong

ObjectivesTo establish the three-dimensional facial soft tissue morphology of adolescent and adult females in the Guangdong population and to study the morphological characteristics of hyperdivergent skeletal class II females in Guangdong compared with that of normodivergent class I groups.Materials and methodsThe 3dMDface system was used to capture face scans of 160 patients, including 45 normal and 35 hyperdivergent skeletal class II adolescents (aged 11–14 years old) and 45 normal and 35 hyperdivergent skeletal class II adults (aged 18–30 years old). Thirty-two soft tissue landmarks were mapped, and 21 linear, 10 angular and 17 ratio measurements were obtained by 3dMDvultus analysis software. Data were assessed with a t-test of two independent samples between the normal adolescent and adult groups and between the normal and hyperdivergent skeletal class II groups.ResultsThe linear measurements of the Guangdong adult females were larger than those of the adolescents in both Class I and Class II groups. However, the angular and ratio measurements had no significant difference. The vertical linear measurements were higher and the sagittal and transverse linear measurements were smaller in the hyperdivergent class II group (p < 0.05). The soft tissue ANB angle, chin-lip angle, and mandibular angle were significantly larger and the soft tissue facial convexity angle and nasal convexity angle were significantly smaller in the hyperdivergent class II group (p < 0.05). Additionally, there were significant differences in the ratio measurements between the hyperdivergent class II groups and the control groups (p < 0.05).ConclusionsThe three-dimensional facial morphology of Guangdong adolescent and adult females was acquired. The facial soft tissue measurements of the adults were higher in the three dimensions except for the facial convexity and proportional relationships which were similar, suggesting that the growth pattern remained the same. The three-dimensional facial soft tissue features of hyperdivergent skeletal class II were characterized by the terms “long, convex, and narrow”. Three-dimensional facial measurements can reflect intrinsic hard tissue characteristics.

The MAKO robotic-arm knee arthroplasty system.

The Mako robotic arm knee arthroplasty system was initially indicated in unicompartmental knee arthroplasty followed by bicompartmental and total knee arthroplasty techniques. The system utilizes three elements: (1) Pre-op 3D CT based planning and image based intra-op navigation. (2) Pre-resection implant modifications with integrated alignment, implant position and gap data, and (3) A semi-constrained robotic arm assisted execution of bone resection with "haptic" boundaries, and cemented implants. This paper evaluates variable pre-op implant placement, and anatomic reference positioning; data entry with incorporation of alignment, implant congruency through range of motion, and gaps; bone resection with "haptic" boundaries, and final implant evaluation with kinetic sensors. The Mako system allowed for improved implant placement utilizing CT guidance, bone resection accuracy, flexibility for functional implant placement with gap balancing. When combined with kinetic sensors, there was improved rotation and soft tissue balance. The MAKO robotic system can assist the surgeon with anatomic landmarks, provides the flexibility for independent gap balance through implant and alignment refinement, and three-dimensional soft tissue balancing data to achieve functional stability. Registry data has shown improved outcome survivorship irrespective of the surgeons' volumes and learning curves.

Three-dimensional analysis of lip soft tissue changes and related jaw changes in patients with skeletal class III malocclusion and facial asymmetry.

To investigate three-dimensional soft tissue changes of lips and related jaw changes in patients with skeletal class III malocclusion and facial asymmetry using cone-beam computerized tomography (CBCT). This study included 46 CBCT scans of patients with aforementioned character before (T1) and 6-12 months after orthognathic surgery (T2). Subjects were divided into 2 groups according to two types of orthognathic surgery namely, the one-jaw surgery group who underwent bilateral sagittal splint ramus osteotomy (BSSRO) and the two-jaw surgery group who underwent Le Fort I osteotomy and BSSRO. Mimics 19.0 software are used for model reconstruction, landmark location and three-dimensional cephalometric analysis. Descriptive statistics and correlation analyses are used to investigate jaw hard tissue and lip soft tissue changes. In one-jaw group, the mandible shows changes in contour and position (p < 0.05), and the surgery causes changes of lip structure on the deviated side. While in two-jaw group, jaws only show changes in spatial position, and surgery changes contour of bilateral lips and nasolabial angle (p < 0.05). At the same time, lip symmetry increases significantly in both groups postoperatively. Orthognathic surgery can improve lip aesthetics in patients with skeletal class III malocclusion and facial asymmetry. However, changes induced by two surgical approaches are different. Surgeons should have a clear acquaintance with this difference to deal with different situations.

Integration of imaging modalities in digital dental workflows - possibilities, limitations, and potential future developments.

The digital workflow process follows different steps for all dental specialties. However, the main ingredient for the diagnosis, treatment planning and follow-up workflow recipes is the imaging chain. The steps in the imaging chain usually include all or at least some of the following modalities: cone-beam computed tomographic data acquisition, segmentation of the cone-beam computed tomography image, intraoral scanning, facial three-dimensional soft tissue capture and superimposition of all the images for the creation of a virtual augmented model. As a relevant clinical problem, the accumulation of error at each step of the chain might negatively influence the final outcome. For an efficient digital workflow, it is important to be aware of the existing challenges within the imaging chain. Furthermore, artificial intelligence-based strategies need to be integrated in the future to make the workflow more simplified, accurate and efficient.

Miniscrew-assisted rapid palatal expander (MARPE) therapeutic results: A review

Background: One of the most common maxillary abnormalities is transverse deficiency, which can be a contributory factor in malocclusions. There are some evidence of successful non-surgical treatment of this type of discrepancy after puberty by using maxillary expansion techniques. The Miniscrew-assisted rapid palatal expander (MARPE) method is a newly introduced method that has attracted the interest of many orthodontists. This study aimed to evaluate the therapeutic results of this technique in a systematic review. Method: In this study, various databases including PubMed, Scopus, and ISI (Web of science) were queried with proper keywords, provided by PICO strategy of research, from 1980 to December 2020. Relevant articles were collected with restrictions on the English language. The full text of papers with all inclusion criteria was assessed. The therapeutic outcomes of MARPE were evaluated in the selected studies. Results: A total of 14 studies were included in the systematic review. Totally, 5 case report studies, 8 retrospective studies, and 1 case series study were reviewed. Cone-beam computed tomography was used as an outcome measure in all studies. In all reviewed studies, maxillary expansion occurred with high success rates in patients. Moreover, respiratory characteristics were also assessed in two studies measuring respiratory muscle strength, airflow and nasal and nasopharyngeal airway volume, showing benefits of MARPE. A study also examined three-dimensional soft tissue stereophotogrammetry. Based on these studies, the indication for using this method was a maxillary transverse deficiency as well as upper and lower arches crowding. No serious complications were reported in any of the reviewed studies. However, most studies did not perform long-term follow-ups and the age range of the subjects was mainly between 12 and 24 years. MARPE has been suggested as a treatment modality for correction of maxillary transverse deficiency in young adults but patients under the age of 14 may also benefit from this treatment in special conditions. Conclusion: A general review of the results of studies showed the high efficiency of MARPE technique in correcting maxillary transverse deficiency.

Population affinity and variation of sexual dimorphism in three-dimensional facial forms: comparisons between Turkish and Japanese populations

Examining the extent to which sex differences in three-dimensional (3D) facial soft tissue configurations are similar across diverse populations could suggest the source of the indirect evolutionary benefits of facial sexual dimorphism traits. To explore this idea, we selected two geographically distinct populations. Three-dimensional model faces were derived from 272 Turkish and Japanese men and women; their facial morphologies were evaluated using landmark and surface-based analyses. We found four common facial features related to sexual dimorphism. Both Turkish and Japanese females had a shorter lower face height, a flatter forehead, greater sagittal cheek protrusion in the infraorbital region but less prominence of the cheek in the parotid-masseteric region, and an antero-posteriorly smaller nose when compared with their male counterparts. The results indicated the possible phylogenetic contribution of the masticatory organ function and morphogenesis on sexual dimorphism of the human face in addition to previously reported biological and psychological characteristics, including sexual maturity, reproductive potential, mating success, general health, immune response, age, and personality.

Accuracy of three-dimensional soft tissue profile prediction in orthognathic surgery.

To evaluate the accuracy of three-dimensional (3D) soft tissue prediction in bimaxillary orthognathic surgery. Cone-beam computed tomographs of 88 patients with class II (n = 46) and class III (n = 42) malocclusions, who underwent bimaxillary orthognathic surgery, were included in this retrospective study. 3D soft tissue prediction and postoperative outcome were compared by using ten landmarks of facial soft tissues. Patients' sex and age were also assessed. Results were analyzed using a mixed model methodology (p < 0.05). The success criterion adopted was a mean discrepancy of < 2mm. Most mandibular landmarks indicated a tendency for underprediction with a downward direction in class II patients, with some values > 2mm. In class III, there was overprediction with a downward direction for the mandibular landmarks, with values < 2mm. More accurate results were found in female and older patients. 3D surgical planning showed clinically acceptable results for predicting soft tissues in patients undergoing bimaxillary orthognathic surgery, with more accurate results for class III patients. Although some differences were found when age and sex were interacted, a consistent association between these variables could not be stated. These results support the clinician, as accuracy can provide a strong guide to the surgeon when planning surgical orthodontic treatment.

Three-dimensional soft tissue changes in orthodontic extraction and non-extraction patients: A prospective study.

To assess the soft tissue changes in orthodontic extraction and non-extraction patients on 3D stereophotogrammetric images. 23 extraction (22.2±9.2years) and 23 non-extraction (20.3±11.1years) consecutive patients were enrolled at the Sections of Orthodontics at Aarhus University and at University of Naples Federico II. All patients had a first 3D image taken after bonding of brackets on the upper incisors (T0), and a second 3D image (T1) after space closure in the extraction group or at insertion of the first SS or TMA rectangular wire in the non-extraction group. The 3D images were captured with 3dMDFace System and analysed with 3dMDVultus Software. After placing 19 landmarks, 15 measurements were obtained. Intragroup changes were analysed with paired t-test and intergroup changes with unpaired t-test (P<.05). Superimpositions of the 3D images at T0 and T1 visualized with colour-coded maps showed that soft tissue changes primarily happened in the perioral area in both groups. The Nasolabial angle increased significantly in the extraction group (3°±4.1, P=.002), while it decreased in the non-extraction group (-1.5°±5.5°, P=.002). There was a significant difference between the two groups (4.4°, P=.004). 3D comparison of the soft tissues in the extraction and non-extraction groups showed statistically significant, but clinically limited differences in the perioral area. The Nasolabial angle was significantly larger at T1 in the extraction group compared with the non-extraction group.

A comparison of postoperative, three-dimensional soft tissue changes in patients with skeletal class III malocclusions treated via orthodontics-first and surgery-first approaches

The aim of this retrospective study was to compare three-dimensional (3D) soft tissue and hard tissue changes between orthodontics-first approach (OFA) and surgery-first approach (SFA) after mandibular setback surgery. All patients underwent bilateral sagittal split osteotomy, and were examined by lateral cephalograms and 3D optical scanner before surgery (T0) and 1 (T1), 3 (T2), and 12 (T3) months after surgery. Three standard angles (FMA, U1 to FH, IMPA) were measured as hard tissue change and the 2 sets of 3D data were superimposed, and volumetric differences were calculated as soft tissue change. Statistical analyses were performed by using unpaired t-tests. Differences with P < 0.05 were considered significant. A total of 39 patients with mandibular prognathism were included in this study. The OFA group consisted of 24 patients and the SFA group of 15 patients. The SFA group exhibited more labial inclination from T1 to T2 (p = 0.008) and T2 to T3 (p = 0.003) than did the OFA group. There were no significant changes at maxilla and mandible at each term of T0, T1, T2 and T3 (p > 0.05), but compared to before surgery, mandibular volume in SFA group significant increased at 1year (p = 0.049) after surgery. We found that the soft tissue changes after the SFA differed significantly from those after the OFA; thus, soft tissue predictions require more care. An analysis of our data compared with OFA and SFA for the patient with mandibular prognathism confirm that the mandibular soft tissue changes by postoperative orthodontic treatment and occlusal relationship in SFA.