***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Purpose Superimposition of two dimensional preoperative and postoperative facial images , including radiographs and photographs , are used to evaluate the surgical changes after orthognathic surgery .  Recently , three dimensional ( 3D ) imaging has been introduced allowing more accurate analysis of surgical changes . Surface based registration and voxel based registration are commonly used methods for 3D superimposition . The aim of this study was to evaluate and compare the accuracy of the two methods . Material s and methods Pre-operative and 6 months post-operative cone beam CT scan ( CBCT ) images of 31 patients were r and omly selected from the orthognathic patient data base at the Dental Hospital and School , University of Glasgow , UK .  Voxel based registration was performed on the DICOM images ( Digital Imaging Communication in Medicine ) using Maxilim software ( Medicim-Medical Image Computing , Belgium ) . Surface based registration was performed on the soft and hard tissue 3D models using VRMesh ( VirtualGrid , Bellevue City , WA ) . The accuracy of the superimposition was evaluated by measuring the mean value of the absolute distance between the two 3D image surfaces . The results were statistically analysed using a paired Student t-test , ANOVA with post-hoc Duncan test , a one sample t-test and Pearson correlation coefficient test . Results The results showed no significant statistical difference between the two superimposition methods ( p<0.05 ) . However surface based registration showed a high variability in the mean distances between the corresponding surfaces compared to voxel based registration , especially for soft tissue . Within each method there was a significant difference between superimposition of the soft and hard tissue models . Conclusions There were no significant statistical differences between the two registration methods and it was unlikely to have any clinical significance . Voxel based registration was associated with less variability . Registering on the soft tissue in isolation from the hard tissue may not be a true reflection of the surgical change Aim The purpose of this study was to present and vali date an innovative semi-automatic approach to quantify the accuracy of the surgical outcome in relation to 3D virtual orthognathic planning among patients who underwent bimaxillary surgery .  Material and Method For the validation of this new semi-automatic approach , CBCT scans of ten patients who underwent bimaxillary surgery were acquired pre-operatively . Individualized 3D virtual operation plans were made for all patients prior to surgery . During surgery , the maxillary and m and ibular segments were positioned as planned by using 3D milled interocclusal wafers . Consequently , post-operative CBCT scan were acquired . The 3D rendered pre- and postoperative virtual head models were aligned by voxel-based registration upon the anterior cranial base . To calculate the discrepancies between the 3D planning and the actual surgical outcome , the 3D planned maxillary and m and ibular segments were segmented and superimposed upon the postoperative maxillary and m and ibular segments . The translation matrices obtained from this registration process were translated into translational and rotational discrepancies between the 3D planning and the surgical outcome , by using the newly developed tool , the OrthoGnathicAnalyser . To evaluate the reproducibility of this method , the process was performed by two independent observers multiple times . Results Low intra-observer and inter-observer variations in measurement error ( mean error < 0.25 mm ) and high intraclass correlation coefficients ( > 0.97 ) were found , supportive of the observer independent character of the OrthoGnathicAnalyser . The pitch of the maxilla and m and ible showed the highest discrepancy between the 3D planning and the postoperative results , 2.72 ° and 2.75 ° respectively . Conclusion This novel method provides a reproducible tool for the evaluation of bimaxillary surgery , making it possible to compare larger patient groups in an objective and time-efficient manner in order to optimize the current workflow in orthognathic surgery Inaccurate visualization of the inter-occlusal relationship has raised an important challenge to virtual planning for  orthognathic surgery  based on cone beam computerized tomography ( CBCT ) . The aim of this study was to evaluate an innovative workflow for orthognathic surgery planning and surgical splint fabrication . The clinical protocol consists of a single cone beam computerized tomography ( CBCT ) scan of the patient , surface scanning of the dental arches with an intraoral digital scanner , and subsequent fusion of the two data sets . The " virtual patient " thus created undergoes virtual surgery , and the result ing file with the intermediate intermaxillary relationship is used to obtain the intermediate splint by CAD/CAM technology ( computer-aided design and computer-aided manufacturing ) . A proof-of-concept study was performed in order to assess the accuracy and reliability of this protocol . The study comprised two parts : an in vitro evaluation on three dentate skull models and a prospect i ve in vivo assessment on six consecutive patients .  Vector error calculation between the virtually simulated intermaxillary position and the intraoperative intermediate intermaxillary relationship revealed high accuracy . The greatest average variation corresponded to the y axis . Compared to previously described methods for obtaining an augmented three-dimensional virtual model , this procedure eliminates the need for dental impressions , simplifies the necessary technical steps and computational work , and reduces the patient 's exposure to ionizing radiation Our purpose was to evaluate the immediate postoperative outcome of preoperatively planned and predicted positional changes in hard and soft tissue in 100 prospect ively and consecutively planned and treated patients ; all had various dentofacial deformities that required single or double jaw orthognathic correction using the computerised , cephalometric , orthognathic , surgical planning system ( TIOPS ) .  Preoperative cephalograms were analysed and treatment plans and prediction tracings produced by computerised interactive simulation . The planned changes were transferred to models and finally to operation . Five to 6 weeks postoperatively , the changes in profile actually obtained in the hard and soft tissue were cephalometrically assessed . The mean accuracy was relatively high . At the cephalometric reference points where significant differences between planned or predicted , and actually obtained , positional changes in hard and soft tissue were apparent and the inaccuracies were , except for the predicted horizontal position of the lower lip , relatively small . However , the variability of the predicted outcome in individual hard and soft tissues was relatively high . Using the TIOPS planning system with the presently included soft tissue algorithms , the current study shows relatively high mean predictability of the immediately postoperative hard and soft tissue outcome , independent of the extent and direction of required orthognathic correction . Because of the relatively high individual variability , caution is required when presenting the planned and predicted positional changes in the hard and soft tissue preoperatively in individual patients PURPOSE The purpose of this prospect i ve multicenter study was to assess the accuracy of a computer-aided surgical simulation ( CASS ) protocol for orthognathic surgery . MATERIAL S AND METHODS The accuracy of the CASS protocol was assessed by comparing planned outcomes with postoperative outcomes of 65 consecutive patients enrolled from 3 centers .  Computer-generated surgical splints were used for all patients . For the genioplasty , 1 center used computer-generated chin templates to reposition the chin segment only for patients with asymmetry .  St and ard intraoperative measurements were used without the chin templates for the remaining patients . The primary outcome measurements were the linear and angular differences for the maxilla , m and ible , and chin when the planned and postoperative models were registered at the cranium . The secondary outcome measurements were the maxillary dental midline difference between the planned and postoperative positions and the linear and angular differences of the chin segment between the groups with and without the use of the template . The latter were measured when the planned and postoperative models were registered at the m and ibular body . Statistical analyses were performed , and the accuracy was reported using root mean square deviation ( RMSD ) and the Bl and -Altman method for assessing measurement agreement . RESULTS In the primary outcome measurements , there was no statistically significant difference among the 3 centers for the maxilla and m and ible . The largest RMSDs were 1.0 mm and 1.5 ° for the maxilla and 1.1 mm and 1.8 ° for the m and ible . For the chin , there was a statistically significant difference between the groups with and without the use of the chin template . The chin template group showed excellent accuracy , with the largest positional RMSD of 1.0 mm and the largest orientation RMSD of 2.2 ° . However , larger variances were observed in the group not using the chin template . This was significant in the anteroposterior and superoinferior directions and the in pitch and yaw orientations . In the secondary outcome measurements , the RMSD of the maxillary dental midline positions was 0.9 mm . When registered at the body of the m and ible , the linear and angular differences of the chin segment between the groups with and without the use of the chin template were consistent with the results found in the primary outcome measurements . CONCLUSIONS Using this computer-aided surgical simulation protocol , the computerized plan can be transferred accurately and consistently to the patient to position the maxilla and m and ible at the time of surgery . The computer-generated chin template provides greater accuracy in repositioning the chin segment than the intraoperative measurements The purpose of this study was to apply a novel method to evaluate surgical outcomes at 1 year after orthognathic surgery for Class III patients undergoing two different surgical protocol s. Fifty patients divided equally into two groups ( maxillary advancement only and combined with m and ibular setback ) had cone beam computed tomography ( CBCT ) scans taken pre-surgery , at splint removal , and at 1-year post-surgery . An automatic cranial base superimposition method was used to register , and shape correspondence was applied to assess , the overall changes between pre-surgery and splint removal ( surgical changes ) and between splint removal and 1-year post-surgery at the end of orthodontic treatment ( post-surgical adaptations ) . Post-surgical maxillary adaptations were exactly the same for both groups , with 52 % of the patients having changes > 2 mm . Approximately half of the post-surgical changes in the maxilla for both groups were vertical . The two-jaw group showed significantly greater surgical and post-surgical changes in the ramus , chin , and most of the condylar surfaces ( P<0.05 ) . Post-surgical adaptation on the anterior part of the chin was also more significant in the two-jaw group ( P<0.05 ) . Regardless of the type of surgery , marked post-surgical adaptations were observed in the regions evaluated , which explain the adequate maxillary-m and ibular relationship at 1-year post-surgery on average , with individual variability In this r and omised controlled clinical trial , 2 homogeneous groups of patients with facial asymmetry ( n=10 in each ) were treated by either classic or computer-assisted orthognathic corrective surgery . Differences between the 2 groups in the alignment of the lower interincisal point ( p=0.03 ) , m and ibular sagittal plane ( p=0.01 ) , and centering of the dental midlines ( p=0.03 ) were significant , with the digital planning group being more accurate The aim of this article is to determine the advantages of 3D planning in predicting postoperative results and manufacturing surgical splints using CAD/CAM ( Computer Aided Design /Computer Aided Manufacturing ) technology in orthognathic surgery when the software program Simplant OMS 10.1 ( Material ise ( ® ) , Leuven , Belgium ) was used for the purpose of this study which was carried out on 16 patients . A conventional preoperative treatment plan was devised for each patient following our Centre 's st and ard protocol , and surgical splints were manufactured . These splints were used as study controls . The preoperative treatment plans devised were then transferred to a 3D-virtual environment on a personal computer ( PC ) . Surgery was simulated , the prediction of results on soft and hard tissue produced , and surgical splints manufactured using CAD/CAM technology . In the operating room , both types of surgical splints were compared and the degree of similitude in results obtained in three planes was calculated . The maxillary osteotomy line was taken as the point of reference . The level of concordance was used to compare the surgical splints . Three months after surgery a second set of 3D images were obtained and used to obtain linear and angular measurements on screen . Using the Intraclass Correlation Coefficient these postoperative measurements were compared with the measurements obtained when predicting postoperative results . Results showed that a high degree of correlation in 15 of the 16 cases . A high coefficient of correlation was obtained in the majority of predictions of results in hard tissue , although less precise results were obtained in measurements in soft tissue in the labial area . The study shows that the software program used in the study is reliable for 3D planning and for the manufacture of surgical splints using CAD/CAM technology . Nevertheless , further progress in the development of technologies for the acquisition of 3D images , new versions of software programs , and further studies of objective data are necessary to increase precision in computerised 3D planning 
    Output:
    
On the basis of the findings of this review , it is evident that the literature lacks consensus regarding accuracy assessment .