Prediction Of Soft Tissue Changes Research Articles

Analysis of facial features and prediction of lip position in skeletal class III malocclusion adult patients undergoing surgical-orthodontic treatment.

This study presents a retrospective study aimed to analyze the facial features at each stage of surgical-orthodontic treatment for skeletal class III malocclusion, and predict the changes in the lips after treatment. There were 49 skeletal class III malocclusion patients treated with bimaxillary surgery and orthodontic treatment enrolled in this study. Lateral cephalograms were obtained before treatment (T0), 1 month before surgery (T1), 1 month after surgery (T2), and after debonding (T3) for cephalometric measurements. After the measurement of the required variables, paired t-test, Pearson's correlation analysis, and multiple linear regression were performed using SPSS 19.0. The main factors associated with changes in the upper lip included ΔUIE-V, ΔA-V, ΔU1A-V, and ΔL1A-V, and those associated with changes in the lower lip included ΔLIE-V, ΔL1A-V, ΔB-V, ΔPog-V, and Δfacial angle. The predicted regression equation for the horizontal change in the upper lip was represented as ΔUL-vertical reference line (VRL) = 9.430 + 0.779 (ΔUIE-VRL) - 0.542(VULT) (P < 0.05) with a mean error of 1.04 mm; the corresponding equation for the lower lip was ΔLL-VRL = -1.670 + 0.530 (ΔB-VRL) + 0.360 (Ls-E) + 0.393 (ΔLIE-VRL) (P < 0.05), with a mean error of 1.51 mm. This study explored the relationship between orthognathic surgery and changes in the lips and obtained the predictive equations of lip position after treatment by using multiple linear regression, which likely offers a reference for prediction of soft tissue changes before surgical-orthodontic treatment in patients with skeletal class III malocclusion. The findings can help dentists to rapidly predict the lip changes after surgical-orthodontic treatment in patients with skeletal class III malocclusion. The study has been registered with the Chinese Clinical Trial Registration (No: ChiCTR1800017694).

Accuracy of Soft Tissue Prediction of 2 Virtual Planning Systems in Patients Undergoing Intraoral Quadrangular Le Fort II Osteotomy.

Background:Virtual surgical planning (VSP) is state of the art in routine clinical work. Visualization of soft tissue changes adds important information for surgical planning. The aim of this study was to evaluate accuracy of soft tissue prediction of 2 VSP systems in patients undergoing an intraoral quadrangular Le Fort II osteotomy.Methods:VSP was performed with the software application IPS Case Designer (IPS) and Dolphin Imaging 11.95 (DOL) in bone and soft tissue structure. Distances were measured at the 3 levels of the face at the infraorbital rim, the sinus floor, and the lateral incisor level with 2 VSP systems (DOL and IPS).Results:A convenience sample of 19 patients was included in the study with a mean age of 21.9 years. From cranial to caudal, mean differences between simulation and postintervention data were as follows: infraorbital rim level: DOL and ST0: mean difference: 2.90 mm; IPS and ST0: 1.70 mm; sinus floor level: DOL and ST0: mean difference: 3.57 mm; IPS and ST0: 1.34 mm; and lateral incisor level: DOL and ST0: mean difference: 2.48 mm; IPS and ST0: 2.25 mm.Conclusions:Generally, both VSP systems are suitable for planning an intraoral quadrangular Le Fort II osteotomy. Especially in the infraorbital region, improvement of the algorithm is required for trustworthy prediction of soft tissue changes.

Prediction of Soft-Tissue Changes Following Single and Bi-Jaw Surgery: An Evaluative Study.

Introduction:Orthognathic surgery is carried out in the hard tissues; however, the patient perceives change in the soft tissue. It is important to accurately predict postoperative facial changes associated with each surgical procedure. This study aims to evaluate the changes in the soft tissues resulting from the movement of the hard tissue following single and bi-jaw surgeries.Materials and Methods:An evaluative clinical study was carried out on a total of 34 subjects which consisted of 52 jaw surgeries. Maxilla and mandible were considered as a separate entity even in bi-jaw cases for evaluation. Surgical procedures performed were either bilateral sagittal split osteotomy, Le Fort I osteotomy or both. Pre- and post-surgical lateral cephalograms were compared to assess the soft-tissue change at various soft-tissue points and were labeled T1 and T2, respectively. The points on maxilla were Point A and PrS on upper lip. The points on mandible were PrI and Point B on lower lip and Pog and Gn on chin.Results:All the points on the maxilla and mandible had a strong correlation between the hard and soft-tissue points except point PrS on upper lip.Discussion:Facial appearance is an important parameter in the present times which influences the social and psychological development of an individual. What patient sees is the external soft-tissue drape whereas orthognathic surgery is carried out on bony components of the face. Thus prediction of soft-tissue changes following surgery is an important part of treatment planning.

Perception of computerised predictions using cephalometric software facad in orthognathic surgery

Introduction: Orthognathic surgery has become a more acceptable treatment modality in conjunction with orthodontic treatment as esthetic awareness has been increased. The criteria for success of an orthognathic surgical procedure are not only centred on the correction of the skeletal and dental abnormalities, but also on an esthetic improvement as judged by both patients and practitioners. Using computer softwares for prediction of orthognathic surgical outcome is gaining more popularity. It was the purpose of the present study to examine the efficacy of prediction of soft tissue changes after performing orthognathic surgeries using the cephalometric software program FACAD. Aims and Objectives: The aim of the study is to assess the perception of facial profile attractiveness and soft tissue outcome in predicted profile images in patients undergoing orthognathic surgery. Materials and Methods: Total of 50 samples aged 20 to 25 years (35 females and 15 males) 20 skeletal class I bimaxillary protrusion cases, 20 skeletal class II cases and 10 skeletal class III cases. Cephalometric radiographs were scanned using Epson V 700 film scanner. The radiographic images were analysed using cephalometric software (FACAD 3.6 )and traced by identifying and placing a series of cephalometric points, both bony and soft tissue. Result: The study suggested that the predicted profile images of all the patients were attractive and rankings were decreasing from class I bimaxillary class III and then class II. The least score of attractiveness were given to class II patients. The predicted profile images of class I bimaxillary patients were more attractive. Conclusion: this study showed that the predicted profile images were attractive as suggested by three raters with class I bimaxillary most attractive and class II least attractive. In overall, laypersons and dental students ratings were somehow similar in the assessment of facial profile attractiveness in the predicted profile images.

The accuracy of three-dimensional prediction of soft tissue changes following the surgical correction of facial asymmetry: An innovative concept

The accuracy of three-dimensional (3D) predictions of soft tissue changes in the surgical correction of facial asymmetry was evaluated in this study. Preoperative (T1) and 6–12-month postoperative (T2) cone beam computed tomography scans of 13 patients were studied. All patients underwent surgical correction of facial asymmetry as part of a multidisciplinary treatment protocol. The magnitude of the surgical movement was measured; virtual surgery was performed on the preoperative scans using Maxilim software. The predicted soft tissue changes were compared to the actual postoperative appearance (T2). Mean (signed) distances and mean (absolute) distances between the predicted and actual 3D surface meshes for each region were calculated. The one-sample t-test was applied to test the alternative hypothesis that the mean absolute distances had a value of <2.0mm. A novel directional analysis was applied to analyse the accuracy of the prediction of soft tissue changes. The results showed that the distances between the predicted and actual postoperative soft tissue changes were less than 2.0mm in all regions. The predicted facial morphology was narrower than the actual surgical changes in the cheek regions. 3D soft tissue prediction using Maxilim software in patients undergoing the correction of facial asymmetry is clinically acceptable.

Accuracy of three-dimensional facial soft tissue simulation in post-traumatic zygoma reconstruction

The aim of this study was to evaluate the accuracy of novel software-CMF-preCADS-for the prediction of soft tissue changes following repositioning surgery for zygomatic fractures. Twenty patients who had sustained an isolated zygomatic fracture accompanied by facial deformity and who were treated with repositioning surgery participated in this study. Cone beam computed tomography (CBCT) scans and three-dimensional (3D) stereophotographs were acquired preoperatively and postoperatively. The 3D skeletal model from the preoperative CBCT data was matched with the postoperative one, and the fractured zygomatic fragments were segmented and aligned to the postoperative position for prediction. Then, the predicted model was matched with the postoperative 3D stereophotograph for quantification of the simulation error. The mean absolute error in the zygomatic soft tissue region between the predicted model and the real one was 1.42±1.56mm for all cases. The accuracy of the prediction (mean absolute error ≤2mm) was 87%. In the subjective assessment it was found that the majority of evaluators considered the predicted model and the postoperative model to be ‘very similar’. CMF-preCADS software can provide a realistic, accurate prediction of the facial soft tissue appearance after repositioning surgery for zygomatic fractures. The reliability of this software for other types of repositioning surgery for maxillofacial fractures should be validated in the future.

Prediction of lip response to orthodontic treatment using a multivariable regression model.

Background:This was a retrospective cephalometric study to develop a more precise estimation of soft tissue changes related to underlying tooth movment than simple relatioship betweenhard and soft tissues.Materials and Methods:The lateral cephalograms of 61 adult patients undergoing orthodontic treatment (31 = premolar extraction, 31 = nonextraction) were obtained, scanned and digitized before and immediately after the end of treatment. Hard and soft tissues, angular and linear measures were calculated by Viewbox 4.0 software. The changes of the values were analyzed using paired t-test. The accuracy of predictions of soft tissue changes were compared with two methods: (1) Use of ratios of the means of soft tissue to hard tissue changes (Viewbox 4.0 Software), (2) use of stepwise multivariable regression analysis to create prediction equations for soft tissue changes at superior labial sulcus, labrale superius, stomion superius, inferior labial sulcus, labrale inferius, stomion inferius (all on a horizontal plane).Results:Stepwise multiple regressions to predict lip movements showed strong relations for the upper lip (adjusted R2 = 0.92) and the lower lip (adjusted R2 = 0.91) in the extraction group. Regression analysis showed slightly weaker relations in the nonextraction group.Conclusion:Within the limitation of this study, multiple regression technique was slightly more accurate than the ratio of mean prediction (Viewbox4.0 software) and appears to be useful in the prediction of soft tissue changes. As the variability of the predicted individual outcome seems to be relatively high, caution should be taken in predicting hard and soft tissue positional changes.

Data-based prediction of soft tissue changes after orthognathic surgery: clinical assessment of new simulation software

The aim of the present study was to evaluate the accuracy of a novel simulation software package (OrthoForecast) for predicting the soft tissue profile after orthognathic surgery. The study included 15 patients with facial asymmetry (asymmetry group), 15 with a skeletal class II jaw relationship (class II group), and 15 with a skeletal class III jaw relationship (class III group). Twenty-four feature points were digitized, and the distances between points on the predicted and actual postoperative images were compared. Thirty-seven calibrated evaluators also graded the similarity of the predicted images compared to the actual postoperative photographs. Comparisons between the predicted and actual postoperative images revealed that the mean difference between feature points was 3.1±1.4mm for the frontal images and 2.9±0.8mm for the lateral images in the asymmetry group; 2.7±0.9 and 2.1±1.6mm, respectively, in the class II group; and 1.8±1.2 and 1.7±1.0mm, respectively, in the class III group. More than half of the evaluators assessed the predicted images as similar to the actual postoperative images in all groups. In conclusion, OrthoForecast can be regarded as useful, accurate, and reliable software to predict soft tissue changes after orthognathic surgery.

Prediction of soft-tissue changes after mandibular advancement surgery with an equation developed with multivariable regression

This was a retrospective cephalometric study in patients undergoing mandibular advancement surgery. Our aim was to provide a more precise estimation of the postsurgical soft-tissue outcomes than can be achieved by using simple ratios of the hard and soft tissues. The lateral cephalograms of 64 patients undergoing mandibular advancement, from before and near the end of treatment, were scanned and digitized with a customized software program. Multivariable regression analyses were used to create prediction equations for soft-tissue changes at pogonion, inferior labial sulcus, labrale inferius, and stomion inferius (all in the horizontal plane). This method of using multiple explanatory variables appears to be useful in the prediction of soft-tissue changes. At least 96% of the variation of each dependent variable was explained by its relationship with the explanatory variables in the relevant multivariable regression equation, and the results appeared to be clinically useful.

Deformable modeling of facial tissue for craniofacial surgery simulation.

While deformable object modeling has been studied by computer graphics specialists for more than two decades, only a few applications in the field of surgical simulation have been developed which provide both real-time and physically realistic modeling of complex, nonlinear tissue deformations. Particularly in craniofacial surgery, the prediction of soft-tissue changes--which result from alterations in the underlying bone structure--is critical to the surgical outcome. The prediction these tissue changes and, therefore, the prognosis of the postoperative appearance of the patient, is still based on empirical studies of the relationship between bone and tissue movements: There exists no physical model which takes into account the individual patient anatomy to simulate the resulting tissue changes during craniofacial surgery. In this article we present two different deformable tissue models which are intergrated in an interactive surgical simulation test bed. Both techniques allow precise preoperative simulation of the resulting soft tissue changes during craniofacial surgery and visualization of the patient's postoperative appearance. The different deformable models are described in detail and both are applied to the same craniofacial case study. The simulation results are shown and compared with regard to the speed and accuracy of the prediction of the patient's postoperative appearance.

Deformable Modeling of Facial Tissue for Craniofacial Surgery Simulation

While deformable object modeling has been studied by computer graphics specialists for more than two decades, on ly a few applications in the field of surgical simulation have been developed which provide both real-time and physically realistic modeling of complex, nonlinear tissue deformations. Particularly in craniofacial surgery, the prediction of soft-tissue changes—which result from alterations in the underlying bone structure—is critical to the surgical outcome. The prediction of these tissue changes and, therefore, the prognosis of the postoperative appearance of the patient, is still based on empirical studies of the relationship between bone and tissue movements: There exists no physical model which takes into account the individual patient anatomy to simulate the resulting tissue changes during craniofacial surgery. in this article we present two different deformable tissue models which are integrated in an interactive surgical simulation testbed. Both techniques allow precise preoperative simulation of the resulting soft tissue changes during craniofacial surgery and visualization of the patient's postoperative appearance. The different deformable models are described in detail and both are applied to the same craniofacial case study. The simulation results are shown and compared with regard to the speed and accuracy of the prediction of the patient's postoperative appearance.

The validity of the prediction of soft tissue profile changes after LeFort I osteotomy using the dentofacial planner (computer software)

The purpose of this study was to examine the validity of the prediction of soft tissue changes after LeFort I osteotomy with the DentoFacial Planner (DFP) (computer software). The preoperative and postoperative lateral cephalograms of 21 white adult orthodontic patients (10 males and 11 females) who underwent only LeFort I osteotomy as part of their overall treatment were digitized. A coordinate system of X and Y axes were used to assess the amount and direction of movement of the maxilla. The SN + 7° was the X axis, and a perpendicular to this plane from nasion was the Y axis. The sample was divided into two groups depending on the amount of forward movement of the maxilla. More than 2 mm of anterior placement of the maxilla comprised the advancement group (13 patients) and less than 2 mm comprised the impaction group (8 patients). The selection criteria for the sample were (1) before and after cephalograms taken with lips in repose and in centric occlusion; (2) all preoperative records taken almost immediately before surgery; (3) postoperative records taken at least 6 months after surgery and checked by regional superimposition of the preoperative and postoperative lateral cephalograms onto the maxilla and the mandible. No tooth movement occurred between the time the records were taken. The following soft tissue landmarks were examined: pronasale, subnasale, stomion superior, middle upper lip, stomion inferior, middle lower lip, labrale inferior, labiomental fold, and pogonion. The results indicate that for some of these landmarks the amount and direction of soft tissue changes differed between the DFP prediction and the actual surgical changes by LeFort I osteotomy. Differences between actual and predicted changes may be partially attributed to the variability of surgical procedures of previous studies that provided the data for the DFP computer software. (A M J O RTHOD D ENTOFAC O RTHOP 1994;105:241-9.)

Long-term stability and prediction of soft tissue changes after LeFort I surgery

Many evaluations of soft tissue changes after orthognathic surgery have been undertaken, and many correlations of soft tissue to hard tissue movements have been established. These studies have not, however, specifically discussed the long-term stability or characteristics of the soft tissue changes. The objectives of this study were (1) to determine the long term stability of soft tissue changes 5 years after LeFort I osteotomy, (2) to determine reliable correlations, if any, of soft tissue changes to bony movements effected in surgery, and (3) to determine the predictability of soft tissue changes as an aid to orthodontic treatment planning. Cephalometric data from 25 patients who were treated with LeFort I osteotomy with or without a concurrent mandibular procedure were analyzed retrospectively. Cases were selected from the patient records of the Department of Oral Surgery of the Vrije Universiteit in Amsterdam, the Netherlands. These patients were followed up at four time points, the last being a mean of 6.1 years after surgery. Analysis of stability data revealed that most horizontal and vertical soft tissue change after LeFort I surgery occurred in the first year after surgery. Significant (> 10%) change continued to occur for subnasale, labrale inferius, upper lip protrusion, lower lip protrusion, and soft tissue convexity during the subsequent 5 years. Hard tissue to soft tissue correlations were calculated and ratios of soft tissue to hard tissue movement were determined for appropriate hard and soft tissue landmarks at four time intervals. Reliable correlations of hard tissue change at surgery to 5-year soft tissue change could be made for 10 variables, which was considerably less frequently than for 1-year soft tissue change. The relatively low reliability of long-term prediction correlations suggests that soft tissue movements may be more independent of hard tissue over time. One-year prediction values were similar to 5-year values and thus could be used for prediction purposes in orthodontic treatment planning. Most short-term hard to soft tissue correlations found in the present study were in the range of those established by previous authors. Long-term hard tissue to soft tissue correlations gave higher ratios of soft tissue movement secondary to maxillary surgery, approaching ratios of 1.0:1.0 for some variables. This finding, as well as the long-term stability data, suggest that soft tissue settling or equilibrium after surgery may take several years to complete.

Long term stability and prediction of soft tissue changes following LeFort I surgery: Gregory A. Hack University of Connecticut, Farmington, Conn., 1991.

Long term stability and prediction of soft tissue changes following LeFort I surgery: Gregory A. Hack University of Connecticut, Farmington, Conn., 1991.

Changes during and following total maxillary osteotomy (le Fort I procedure): a cephalometric study.

Profile radiographs of 16 adult patients before, subsequent to, and one year following a total maxillary osteotomy were studied. The purpose of the study was to evaluate (1) osseous stability, (2) the relation between hard and soft tissue changes, and (3) the predictability of soft tissue changes on the basis of operative changes. The displacement of the maxilla in relation to the cranial base was expressed as a translation and a rotation. Correlation and stepwise regression analyses were the statistical methods applied. Conclusions: Hard tissue changes were stable in the horizontal plane whereas maxillary intrusion continued following the operation. The ratio between hard and soft tissue changes was low for nose and subnasal structures whereas the upper lip seemed to follow the underlying structures. Soft tissue changes had a low predictability when related to x and y coordinates of the underlying hard tissue but were markedly influenced by the rotational changes with maxillary plane.

Soft tissue response to upper incisor retraction in boys.

The paper describes the lip morphology and treatment changes in two groups of boys with slight (3–4 mm) and marked (8–10 mm) overjets. The results show that the initial morphological differences are greatest in the lower lip and these are maintained even after treatment. In individuals with a small overjet, the upper lip response is more closely related to the degree of incisor retraction than in individuals with marked overjet. Correction of the great overjets results in approximately similar upper and lower lip retraction. The results generally show great variability, and thus indicate that prediction of soft tissue changes in an individual case is difficult.