1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
CRANIOMAXILLOFACIAL DEFORMITIES/COSMETIC SURGERY
The Impact of Orthognathic Surgery on Facial Expressions Q15
Q2 Q3
Ali Al-Hiyali, BDS, MSc,* Ashraf Ayoub, BDS, MDS, PhD,y Xiangyang Ju,z Mohammad Almuzian, BDS, MSc,x and Thamer Al-Anezi, BMS, BM BCh, BDS, MSck Purpose:
The aim of this pilot study was to evaluate the impact of orthognathic surgical correction of facial asymmetry and maxillary hypoplasia on the magnitude and pattern of facial expressions.
Patients and Methods:
This study was carried out on 2 cohorts of patients: in group 1, 10 patients had surgical correction of facial asymmetry; in group 2, 13 patients had Le Fort I osteotomy to correct maxillary hypoplasia. The patients were asked to perform 3 facial expressions (maximal smile, lip purse, and cheek puff) that were recorded using the Di4D image-capture system before and after surgery. The capture of each expression generated 180 3-dimensional (3D) facial images. Twenty-seven facial soft tissue landmarks were digitized on the first frame of the 3D image of each expression and a mathematical generic mesh was applied on the 3D model to clone each patient’s face. The cloned mesh was superimposed automatically on each sequence of the 3D images to evaluate the pattern of facial expressions. The digitization of facial landmarks was satisfactorily accurate and reproducible.
Results:
In group 1, the asymmetry of facial expressions was significantly decreased after surgical correction (P = .0458). In group 2, Le Fort I osteotomy decreased the magnitude of facial expressions (P = .0267).
Conclusion: Q7
This study confirmed that orthognathic surgery affects the dynamics of facial expressions; this should be considered when planning the surgery and informing patients about the surgical correction of dentofacial deformities. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1-11, 2015 Facial expressions are the most common means of communication among humans, with 55% of daily social interactions being nonverbal and dependent on facial expressions.1 In addition, dentofacial deformities are associated with compromised facial expressions.2 In living creatures, flawless bilateral facial and body symmetry is a hypothetical concept that rarely exists. Minor asymmetry exists in pleasing-looking faces and does not require treatment. For minor facial asymme-
Q4
try, the right half of the face is frequently wider than the left, with the chin deviated to the left.3 Maxillary hypoplasia combined with relative mandibular excess results in skeletal Class III skeletal deformity; this deformity esthetically affects the attractiveness of the affected individuals. Most patients with Class III skeletal deformity have the appearance of an angry person and they look older than their actual age; therefore, they seek treatment to improve their facial esthetics.4 Maxillary hypoplasia and facial
*Department of Oral and Maxillofacial Surgery, Faculty of
kDepartment of Oral and Maxillofacial Surgery, Faculty of
Medicine, College of Medical, Veterinary and Life Sciences,
Medicine, College of Medical, Veterinary and Life Sciences,
Glasgow University Dental Hospital and School, Glasgow, UK.
Glasgow University Dental Hospital and School, Glasgow, UK.
yProfessor, Department of Oral and Maxillofacial Surgery, College
Address correspondence and reprint requests to Dr Ayoub:
of Medical, Veterinary and Life Sciences, University of Glasgow
Department of Oral and Maxillofacial Surgery, University of Glasgow,
Medical School, Glasgow, UK.
Dental School, 378 Sauchiehall Street, Glasgow G2 3JZ, UK; e-mail:
zSenior Software Engineer, Medical Devices Unit, NHS Greater Glasgow and Clyde; Honorary Research Fellow, Faculty of
[email protected] Received March 11 2015
Medicine, College of Medical, Veterinary and Life Sciences,
Accepted May 13 2015
Glasgow University Dental Hospital and School, Glasgow, UK.
Ó 2015 American Association of Oral and Maxillofacial Surgeons
xFaculty of Medicine, College of Medical, Veterinary and Life
0278-2391/15/00592-3
Sciences, Glasgow University Dental Hospital and School,
http://dx.doi.org/10.1016/j.joms.2015.05.008
Glasgow, UK.
1 FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112
113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168
2
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
asymmetry are among the common facial deformities that are readily correctable with orthognathic surgery.5-8 However, the impact of orthognathic surgery on facial expressions has not been fully investigated. The most common concerns of patients who seek orthognathic surgery are the dysmorphology of facial appearance at rest and with facial expressions. Expressions are dependent on the movement of facial muscles and their relation to underlying bones. Therefore, it is logical to assume that orthognathic surgery will alter the orientation of facial muscles. It also has been suggested that postsurgical stability is dependent on muscle balance and that relapse is more likely if the functional impairments of facial expressions persist after orthognathic surgery.9 Several studies have assessed the impact of orthognathic surgery on the bony structures and the covering soft tissue10-14; however, the impact of orthognathic surgery on the dynamics of facial expressions is rarely investigated.9,15-17 The published studies on this topic have limitations. The direct placement of multiple markers on a patient’s face before image captures can vary between imaging sessions, which introduces inaccuracies into the assessment. Direct application of facial markers also is time consuming for the clinician and requires a high level of cooperation from the patient. Moreover, the application of markers onto the face could prevent the achievement of a natural facial expression.18,19 The small number of landmarks to describe facial movements limits the comprehensiveness of the analysis and the interpretation of the results.17 Various methods have been developed to assess facial expressions,19-21 some of them are 2-dimensional, including photography and videotaping. However, these methods underestimate the magnitude of facial expressions by 43%.22 Facial expressions also have been assessed using 3-dimensional (3D) statistic imaging-based systems.23 However, these methods do not record or analyze the dynamic of facial expressions. The objective assessment of facial muscle movements requires the recording of the associated expressions in a dynamic state. Static capture of maximum facial expressions does not record the direction, speed, and pattern of facial movements, which limits the robustness of the analysis.6 Various 3D dynamic motion-capture systems have been developed recently that are based on active stereophotogrammetry, in which a textured pattern is projected onto the face to aid the 3D build of the facial model,24 or passive stereophotogrammetry, which depends on skin texture to build the 3D facial models.25 The dynamic imaging system captures 60 3D images of the face per second; the capture of each expressions takes approximately 3 seconds, which generates approximately 180 3D facial images for analysis. Facial landmarks are digitized on
the first 3D facial image, and their locations are automatically tracked throughout the sequence of the images of the captured facial expression. The accuracy of the software in tracking the digitized facial landmarks across the sequence of the 3D images of each facial expression captured by a passive stereophotogrammetry imaging system has been validated26 and the clinical application of the method has been tested.27 The purpose of this study was to investigate the impact of orthognathic surgical correction of maxillary hypoplasia and facial asymmetry on facial expressions.
Patients and Methods This study was carried out on 2 cohorts of patients: 10 patients (5 male and 5 female; 17 to 29 yr old) who had surgical correction of facial asymmetry (group 1) and 13 patients (8 female and 5 male; 18 to 50 yr old) who had had Le Fort I osteotomy to address maxillary hypoplasia (group 2). All patients were treated by the same surgeon and followed a standard protocol of data recording and analysis before and after surgery. Preoperative facial expressions were captured 1 week before surgery and 6 to 18 months after surgery (Table 1) using the Di4D capture system (Dimensional Imaging Limited, Glasgow, UK). The system consisted of 2 gray-scale cameras (Model avA 160065km/kc; resolution, 1,600 1,200 pixels; sensor model KAI-02050; Kodak, Basler, Germany), 1 color camera that captured 60 frames per second, and a lighting system (Model DIV-401-DIVALITE; Kino Flo Corporation, Burbank, CA). The system was connected to a personal computer (Win 8.1 professional; Intel Core i7; CPU, 3.40 GHz; RAM, 32.0 GB). The Di4D system was calibrated before each capture session to synchronize the intrinsic camera parameters. The image recording and building of the dynamic 3D imagines were based on passive stereophotogrammetry, which allowed the automatic tracking of facial landmarks throughout the sequence of the captured images of each facial expression. Three nonverbal, reproducible facial expressions were captured in this study, which included maximal smile, lip purse, and cheek puff, according to a previously published protocol.18,20,21 Patients sat in an upright and comfortable position at a 95-cm distance from the cameras. Patients were asked to keep their eyes open and remain relatively still during image capturing. The system’s illumination lights were adjusted by the operator to avoid excessive brightness that could affect the patient’s facial expressions. Three facial expressions were recorded: maximum smile, lip purse, and cheek puff (Fig 1). Ethics approval was granted to conduct this study under the Integrated
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
Q1
169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224
3
AL-HIYALI ET AL
225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280
Table 1. DEMOGRAPHIC DISTRIBUTION OF CASES IN THE 2 GROUPS Q11
Patient Number Group 1 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 Group 2 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13
Age (yr)
Gender
Performed Surgical Procedure
Follow-Up (mo)
20 20 21 20 29 17 19 20 18 18
M M M F F M M F F F
Le Fort I osteotomy + genioplasty BSSO Bimaxillary osteotomy, Le Fort I + BSSO Bimaxillary osteotomy, Le Fort I + BSSO Bimaxillary osteotomy, Le Fort I + BSSO bimaxillary osteotomy, Le Fort I + BSSO Bimaxillary osteotomy, Le Fort I + BSSO Bimaxillary osteotomy, Le Fort I + BSSO BSSO BSSO + genioplasty
5 8 6 6 6 6 5 8 18 18
41 20 20 19 41 19 45 20 49 27 50 18 20
M F F M M F M M F F F F F
Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy
6 6 6 6 6 6 6 6 6 6 6 6 6
Abbreviations: BSSO, bilateral sagittal split osteotomy; F, female; M, male. Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
Research Application System GN12DN441 (protocol 1 18) and sponsored by the UK NHS Greater Glasgow and Clyde health board.
DATA PROCESSING
A set of facial landmarks (Table 2) was digitized on the first 3D facial model of each of the 3D sequence of images for each facial expression. The position of these landmarks was tracked automatically across the set of 180 3D sequences of facial images for each expression. To assess the errors of the method, facial soft tissue landmarks of 10 cases were digitized twice, 1 week apart, by the same operator for each of the 3 captured expressions. A novel method was applied to assess the impact of orthognathic surgery on facial expressions using a generic mesh (Fig 2). The generic mesh consists of 1,982 points and was adapted to the morphologic characteristic of the face to generate a confirmed mesh that was specific to each case. The first frame of each 3D sequence for each expression and its related generic mesh were selected for manual digitization of 27 anthropometric facial landmarks (Table 2).28-30 The
landmarks on the first 3D frame were used to clone (transform) a generic mesh to the 3D model in the first frame (Fig 3). The cloned (transformed) mesh was automatically tracked throughout the sequence of the 3D imagining of each expression. The coordinated tracked facial landmarks were saved for statistical analysis.
STATISTICAL ANALYSIS
The analysis of variance (ANOVA) linear mixedeffects (LME) model was applied to test the impact of the orthognathic surgery on the 3 facial expressions at a chosen level of significance (P < .05). The LME model represents a model of a response variable with fixed and random effects. For each fixed-effects term, ANOVA performs a t test to determine whether all coefficients representing the fixed-effects term are equal to 0. Facial asymmetry score and maximal distance changes of facial expressions were analyzed in this study. To investigate the dissimilarity in the shape of lips, cheeks, and chin regions, each 3D facial image was mirror imaged; the reflected image was superimposed on its own original configuration
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
Q12
281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
print & web 4C=FPO
337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392
4
FIGURE 1. Three-dimensional image sequence of the captured maximum smile before surgical correction. All expressions were captured from Q10 rest to maximum positions. Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
(shape) using partial Procrustes analysis (PPA). The process of mirror reflection of each 3D image was based on the equation x = x x(1), which allowed the entire set of 3D images to be ‘‘mirrored’’ around the x axis to obtain a mirror-like reflection. PPA allowed the maximum superimposition of corresponding shapes by transformation (rotation without scaling). PPA was applied in this study to maintain the original sizes of the tested regions (lips, cheeks, and chin). PPA allowed the values of the differences between the original and mirror-reflected 3D images to be measured as the sum of squared distances of the corresponding vertices, which represented the asymmetry score in each 3D facial image. The average scores from at rest to maximal expression measured the asymmetry of the facial movements. An ANOVA LME model was applied to test the impact of surgery on the asymmetry scores of facial expressions as a fixed effect and the types of facial expression and gender as random effects. The 3 recorded facial expressions were amalgamated together and analyzed collectively to evaluate the impact of orthognathic surgery on these facial movements. The scores obtained from the PPA were tested using the ANOVA LME model to generate the facial asymmetry score. This protocol was applied for each sequence of facial expressions that were recorded before and after surgery for each case in the 2 groups. The method also was applied to measure the differences of the vertices in the lips, cheeks, and chin regions. Differences in the magnitude of maximal expressions were investigated in this study. The tracked
coordinates of facial landmarks were used to assess the magnitude of maximal movement for each of the recorded facial expressions before and after surgery. The change from the rest position (first 3D frame of facial expression) to maximal expression (peak 3D frame of the same facial expression) was tracked and calculated using correspondence analysis (CA). CA is a statistical method based on mapping the difference between 2 facial confirmed meshes. The obtained CA scores were analyzed by the ANOVA LME model to assess the impact of orthognathic surgery on the magnitude of facial expressions.
Results ERRORS OF THE METHOD
The mean differences among the repeated landmark procedures of the 3D facial images were 0.1, 0.2, and 0.6 mm in the x, y, and z directions, which confirmed that the landmark technique was accurate and reproducible. GROUP 1 (SKELETAL FACIAL ASYMMETRY)
There was a significant difference in facial expression asymmetry scores as a result of the surgical correction (P = .0458; Fig 4). The improvement in the symmetry of facial expressions for this group of patients is illustrated in the color mapping of Figure 5, which shows the degree of deference between the Q8 2 surface meshes by a color scale graded in millimeters.
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448
5
AL-HIYALI ET AL
449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504
Table 2. NAMES AND DEFINITIONS OF LANDMARKS THAT WERE DIGITIZED ON THE 3-DIMENSIONAL IMAGE
Landmark Number Q13
Landmark Name
1 and 5
Exocanthion
2 and 4
Endocanthion
3
Glabella
6 and 8 7
Superciliary points Nasion
9
Pronasale
10
Subnasale
11
Labrale superius
12
Labrale inferius
13 14 and 19
Pogonion Zygion
15 and 20
Alar curvature
Q6
16 and 21
Subalare
Q5
17 and 22 18 and 23 24 and 25
Crista philter Cheilion Right and left upper middle lateral lip points Right and left lower middle lateral lip points
Q14
26 and 27
Description Point at the outer commissure of the eye fissure, located slightly medial to the bony exocanthion Point at the inner commissure of the eye fissure, located lateral to the bony landmark Most prominent midline point between the eyebrows, identical to the bony glabella on the frontal bone Points located above the most superior aspects of the eyebrows Point in the midline of the nasal root and the nasofrontal suture, always above the line that connects the 2 inner canthi; identical to the bony nasion Most protruded point of the nose identified in the lateral view of the rest position of the head Midpoint of angle at the columella base where the lower border of the nasal septum and the surface of the upper lip meet Point indicating maximum convexity of the mucocutaneous junction of the upper lip and philtrum Point indicating maximum convexity of the mucocutaneous border of the lower lip Most anterior midpoint of the chin Most prominent point on the cheek area beneath the outer canthus and slightly medial to the vertical line passing through it; different from the bony zygion Most lateral point on the curved base line of each ala, indicating the facial insertion of the nasal wing base Point on the margin of the base of the nasal ala where the ala disappears into the upper lip skin Peak of cupid’s bow of the upper inferior point located at the corner of each labial commissure Midpoints located between the cheilion and labrale superius
Midpoints located between the cheilion and labrale inferius
Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
There was no significant difference in the magnitude of facial expression as a result of orthognathic surgical correction of asymmetry (P = .1984; Fig 6); the differences in the maximal distance of facial expressions are shown by color mapping (Fig 5). The measured distance was recorded between the 3D facial image of first frame of capture (rest position) and the 3D image at maximal peak (maximum expression).
GROUP 2 (MAXILLARY HYPOPLASIA)
Changes in the symmetry of facial expressions as a result of Le Fort I osteotomy were not significant (P = .6994; Fig 7). There was a significant difference in the magnitude of facial expressions before and after surgery (P = .0267; Fig 8); the differences are presented by the color mapping illustrations (Fig 9). The measured
distance was between the first 3D image (rest position) and the peak 3D image (maximum expression).
Discussion Facial expressions have an impact on the diagnosis of facial soft tissue impairments, planning of the surgical correction, and assessment of surgical outcomes.27,31 Therefore, it is important for clinicians to evaluate the dynamics of facial expressions before the surgical planning for the correction of skeletal deformities. It also is valuable to evaluate the changes in the pattern and magnitude after orthognathic surgery, which can affect the stability of the achieved results.6,9,16,17 Various 3D dynamic motion analysis systems have been used for the assessment of facial expressions. These systems track markers on the face or track pixels of the facial images. These systems have been
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560
print & web 4C=FPO
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
FIGURE 2. Generic mesh used to evaluate the dynamic changes of facial expressions. Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
used to assess facial expressions,2,30-36 after nonorthognathic surgical procedures, and to quantify the symmetry of normal facial movements.23,28,37-40 The first video-based study to investigate the impact of orthognathic surgery on facial expressions was
conducted on 19 patients.9 Eleven patients had skeletal Class II mandibular retrognathia, 5 patients had anterior open bite, and the other 3 patients had skeletal Class III maxillomandibular relation. A set of 34 spherical, retroreflective markers, 2 mm in diameter, were attached by eyelash adhesive to specific anthropologic landmarks on the patients’ faces, and facial expressions were recorded by a video-based tracking system (Motion Analysis; Motion Analysis Corporation, Santa Rosa, CA). Seven facial animations were performed by each patient, including the instructed maximal smile, lip purse, mouth opening, cheek puff, eye opening, eye closure, grimace, and a natural smile animation. The aim was to measure the relative change or percentage of change in distance from rest to maximal animation between corresponding pairs of landmarks. There was a statistical difference in the magnitude of animations after surgery, with the most important changes detected in the lip purse animation. These findings suggested that facial movements are affected by skeletal malocclusion and orthognathic surgical procedures. The results showed that all changes were related to the direction of the facial expressions and these varied for each patient group in the study. However, the symmetry and magnitude of facial expressions were not assessed. A 3D laser scanner was used to assess the effect of orthognathic surgery on facial expressions16 in 11 cases that required orthognathic surgery. Only 13 landmarks were directly placed on the patients’ faces before capturing 5 basic facial expressions (frowning, eye closure, grimace, smile, and lip purse). The facial images were captured at 1 week before surgery and
print & web 4C=FPO
561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616
6
FIGURE 3. Transformed mesh (generic mesh) to track the changes of anatomic landmarks throughout the sequence of 3-dimensional capture during facial expressions (patient from facial asymmetry group). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672
7
FIGURE 4. Boxplot showing changes in the asymmetry score of facial expressions after surgery (group 1). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
at 3, 6, and 12 months postoperatively. The displacement of every landmark at specific intervals was investigated. A change in the symmetry of facial expressions as a result of surgery was detected. At 1-year follow-up, the magnitude of facial movements was statistically similar to that recorded before surgery. The path of
movement of facial landmarks was not tracked and the results were based only on the positional differences between rest and maximum expression. The landmarks-based analysis has limitations, and the anatomic areas between the landmarks were not considered in this study. The direct placement of multiple markers on the face before image capture is a major obstacle for the assessment of facial expressions. This can vary between sessions and among operators, which contributes to the errors of the method and affects the reliability of the assessment. Direct marker placement also is time consuming for the patient and the clinician and could prevent the patient from producing a natural facial expression.18,19 The applied generic mesh in the present study was an innovation in assessing the impact of orthognathic surgery on facial expressions. The confirmed mesh is considered a fingerprint that captures facial patterns and morphologic characteristics of each patient’s face. The 27 landmarks that were digitized on the 3D facial model in this study were used only to guide the cloning of the facial mesh for the transformation process of the generic mesh to produce the confirmed mesh. The application of the confirmed meshes in the
print & web 4C=FPO
673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728
print & web 4C=FPO
AL-HIYALI ET AL
FIGURE 5. Illustration of the change of symmetry of the maximum smile after surgery shown on photorealistic images and color-coded facial masks (group 1). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784
print & web 4C=FPO
print & web 4C=FPO
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
FIGURE 6. Boxplot showing changes in maximal distance of facial expressions after surgery (group 1). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
tracking process allowed the automatic tracking of up to 3,000 anatomic corresponding ‘‘vertices’’ that improve the accuracy and comprehensive nature of the morphometric analysis. In this study, only the lips, cheeks, and chin regions were analyzed, because these were the anatomic regions most affected by the captured facial expressions. The confirmed mesh of the 3 anatomic regions contained 469 facial points for analysis and tracking of facial expressions. The results showed that in asymmetric cases there was a statistical difference in asymmetry scores between preoperative and postoperative facial expressions. Orthognathic surgical correction of facial asymmetry improved the associated asymmetry of facial muscle movements. Surgery produced more balance to the dynamics of the movements of the attached facial muscles and the related expressions.
print & web 4C=FPO
785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840
8
FIGURE 7. Boxplot showing changes in asymmetry score of facial expressions after surgery (group 2). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
FIGURE 8. Boxplot showing changes in maximal distance of facial expressions after surgery (group 2). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
Orthognathic correction of the facial bones led to repositioning of the muscles, fat, and associated skin in a more symmetric position. This positional change of the muscle attachments might have resulted in changing the direction and magnitude of facial expressions. The indirect effect of surgery is on the proprioception and motor activity of the muscles of facial expressions, especially those of the lips, cheeks, and chin regions. This would contribute to the changes in the direction and magnitude of facial expressions. The authors acknowledge the heterogeneity of the sample of asymmetric cases regarding the surgical approach for the correction of the underlying asymmetry. However, the common denominator in all cases was the asymmetry of facial expressions. The performed surgery, Le Fort I osteotomy or sagittal split osteotomy, changes the orientation of the orbicularis oris muscle and other muscles of facial expressions, improving the symmetry of facial movements. The main objective of this study was the evaluation of the dynamic and magnitude of facial expressions before and after surgery. The sample is too small to correlate the magnitude of the surgical movements with the observed changes in the pattern and magnitude of facial expressions. In addition, the thickness of the soft tissue was not measured in this study owing to the lack of a standardized protocol and a reliable method for this measurement. To the authors’ knowledge, there is no evidence in the literature to show a clear correlation between tissue thickness and the dynamics of facial expressions. In group 2, the physiologic explanation of the statistical difference in the magnitude of animations could be due to the fact that Le Fort I maxillary advancement stretches the attachments of the muscles of facial
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896
9
897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952
print & web 4C=FPO
AL-HIYALI ET AL
FIGURE 9. Illustration of the change of the symmetry of the maximum smile after surgery shown on photorealistic images and color-coded facial masks (group 2). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
expressions. These findings are complementary to a previous study that showed that mandibular setback surgery increases the magnitude of lip movements,9 which produces the opposite effect of Le Fort I maxillary advancement on the attachment of the lip muscles. The latter will cause stretching of the attached muscles to the maxilla, and this might have contributed to the decreased magnitude of lip movements. However, the long-term impact of maxillary advancement on lip movement was not examined in this study and warrants further investigation.
It is likely that the magnitude of surgical movement would influence the change in facial expressions; however, owing to the small sample, the evaluation of the relation between surgical movements and the change in the pattern of facial expressions has limited value in this study. A longer follow-up is highly desirable; it might show that the magnitude of facial expressions gradually returns to its preoperative measurement. However, patients should be warned of the expected restriction in facial expressions during the first 6 months after surgery. A larger sample would lend
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064
10
Q9
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
itself to a more intensive analysis on the relation between skeletal jaw movements and the change in the dynamic of facial expressions. Another limitation of this study is the amalgamation of the 3 facial expressions for the analysis of the impact of orthognathic surgery on muscle movements. One could argue that the changes of one expression in one direction cancel the changes of another expression in an opposite direction. A larger sample would have allowed the study of the impact of orthognathic surgery on each facial expression separately and a more robust conclusion on understanding the relation between the surgical movements of the osteotomy segments and the attached muscles. This study did not investigate the relation among the extent of surgery, 1- or 2-jaw surgery, the magnitude and direction of movements of the osteotomy segments (yaw, pitch, and roll), and the recorded changes in facial expressions. A larger sample would be required to answer these questions. Nevertheless, the study shows clearly the impact of orthognathic surgery on the magnitude and overall symmetry of facial expressions. The authors hope this study inspires a more comprehensive investigation on a more homogenous group of orthognathic cases. They acknowledge this article does not provide the answers to all these questions; it is just the first step in highlighting the importance of investigating the dynamics of facial expressions and evaluating the impact of orthognathic surgery on the symmetry and magnitude of these movements. Correction of facial asymmetry improved facial symmetry. The magnitude of facial expressions was decreased after Le Fort I osteotomy. The asymmetry score developed in this study is a novel and sensitive tool in quantifying facial expressions that could have a broad clinical application in the assessment of facial muscle movements.
References 1. Mehrabian A: Inference of attitudes from nonverbal communication in two channels. J Consult Psychol 31:248, 1967 2. Weeden JC, Trotman CA, Faraway JJ, et al: Three dimensional analysis of facial movement in normal adults: Influence of sex and facial shape. Angle Orthod 71:132, 2001 3. Cheong YW, Lo LJ: Facial asymmetry: Etiology, evaluation, and management. Chang Gung Med J 34:341, 2011 4. Posnick JC: Orthognathic Surgery: Principles and Practice. New York, NY, Elsevier, 2014, pp 686–757 5. Proffit WR, Turvey TA, Phillips C: Orthognathic surgery: A hierarchy of stability. Int J Adult Orthodon Orthognath Surg 11:191, 1996 6. Johns FR, Johnson PC, Buckley MJ, et al: Changes in facial movement after maxillary osteotomies. J Oral Maxillofac Surg 55: 1044, 1997 7. Bauer RE, Ochs MW: Maxillary orthognathic surgery. Oral Maxillofac Surg Clin North Am 26:523, 2014 8. Severt TR, Proffit WR: The prevalence of facial asymmetry in the dentofacial deformities population at the University of North Carolina. Int J Adult Orthodon Orthognath Surg 12:171, 1996
9. Nooreyazdan M, Trotman CA, Faraway JJ: Modeling facial movement: II. A dynamic analysis of differences caused by orthognathic surgery. J Oral Maxillofac Surg 62:1380, 2004 10. Katsumata A, Fujishita M, Maeda M, et al: 3D-CT evaluation of facial asymmetry. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 99:212, 2005 11. Trpkova B, Prasad NG, Lam EW, et al: Assessment of facial asymmetries from posteroanterior cephalograms: Validity of reference lines. Am J Orthod Dentofacial Orthop 123:512, 2003 12. Yamamoto M, Takaki T, Shibahara T: Assessment of facial asymmetry based by subjective evaluation and cephalometric measurement. J Oral Maxillofac Surg Med Pathol 24:11, 2012 13. Forsberg CT, Burstone CJ, Hanley KJ: Diagnosis and treatment planning of skeletal asymmetry with the submental-vertical radiograph. Am J Orthod 85:224, 1984 14. Bishara SE, Burkey PS, Kharouf JG: Dental and facial asymmetries: A review. Angle Orthod 64:89, 1994 15. Wachtman GS, Cohn JF, VanSwearingen JM, et al: Automated tracking of facial features in patients with facial neuromuscular dysfunction. Plast Reconstr Surg 107:1124, 2001 16. Verze L, Bianchi FA, Dell’Acqua A, et al: Facial mobility after bimaxillary surgery in Class III patients: A three-dimensional study. J Craniofac Surg 22:2304, 2011 17. Popat H, Richmond S, Marshall D, et al: Three-dimensional assessment of functional change following Class 3 orthognathic correction—A preliminary report. J Craniomaxillofac Surg 40: 36, 2012 18. Sawyer AR, See M, Nduka C: Assessment of the reproducibility of facial expressions with 3-D stereophotogrammetry. Otolaryngol Head Neck Surg 140:76, 2009 19. Frey M, Giovanoli P, Gerber H, et al: Three-dimensional video analysis of facial movements: A new method to assess the quantity and quality of the smile. Plast Reconstr Surg 104: 7, 1999 20. Johnston DJ, Millett DT, Ayoub AF, et al: Are facial expressions reproducible? Cleft Palate Craniofac J 40:291, 2003 21. O’Leary E, Ju X, Khambay B, et al: Evaluation of the reproducibility of non-verbal facial animations. Lecture Notes Comput Sci 7378:184, 2012 22. Gross MM, Trotman CA, Moffatt KS: A comparison of threedimensional and two-dimensional analyses of facial motion. Angle Orthod 66:189, 1996 23. Hajeer MY, Ayoub AF, Millett DT: Three-dimensional assessment of facial soft-tissue asymmetry before and after orthognathic surgery. Br J Oral Maxillofac Surg 42:396, 2004 24. Popat H, Richmond S, Benedikt L, et al: Quantitative analysis of facial movement—A review of three-dimensional imaging techniques. Comput Med Imaging Graph 33:377, 2009 25. Mishima K: Analysis methods for facial motion. Jpn Dent Sci Rev 45:4, 2009 26. Al-Anezi T, Khambay B, Peng MJ, et al: A new method for automatic tracking of facial landmarks in 3D motion captured images (4D). Int J Oral Maxillofac Surg 42:9, 2013 27. Shujaat S, Khambay BS, Ju X, et al: The clinical application of three-dimensional motion capture (4D): A novel approach to quantify the dynamics of facial animations. Int J Oral Maxillofac Surg 43:907, 2014 28. Farkas L: Anthropometry of the Head and Face (ed 2). New York, NY, Raven Press, 1994, pp 79–88 29. Sawyer AR, See M, Nduka C: Quantitative analysis of normal smile with 3D stereophotogrammetry—An aid to facial reanimation. J Plast Reconstr Aesthet Surg 63:65, 2010 30. Hajeer MY, Ayoub AF, Millett DT, et al: Three-dimensional imaging in orthognathic surgery: The clinical application of a new method. Int J Adult Orthodon Orthognath Surg 17: 318, 2002 31. Trotman CA: Faces in 4 dimensions: Why do we care, and why the fourth dimension? Am J Orthod Dentofacial Orthop 140: 895, 2011 32. Popat H, Richmond S, Playle R, et al: Three-dimensional motion analysis—An exploratory study. Part 1: Assessment of facial movement. Orthod Craniofac Res 11:216, 2008
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120
11
AL-HIYALI ET AL
1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131
33. Popat H, Richmond S, Zhurov AI, et al: A geometric morphometric approach to the analysis of lip shape during speech: Development of a clinical outcome measure. PLoS One 8: e57368, 2013 34. Mishima K, Yamada T, Matsumura T, et al: Analysis of lip motion using principal component analyses. J Craniomaxillofac Surg 39: 232, 2011 35. Trotman CA, Faraway JJ: Sensitivity of a method for the analysis of facial mobility. II. Interlandmark separation. Cleft Palate Craniofac J 35:142, 1998 36. Trotman CA, Faraway JJ: Modeling facial movement: I. A dynamic analysis of differences based on skeletal characteristics. J Oral Maxillofac Surg 62:1372, 2004
37. Trotman CA, Faraway JJ, Phillips C: Visual and statistical modeling of facial movement in patients with cleft lip and palate. Cleft Palate Craniofac J 42:245, 2005 38. Hontanilla B, Auba C: Automatic three-dimensional quantitative analysis for evaluation of facial movement. J Plast Reconstr Aesthet Surg 61:18, 2008 39. Tzou CH, Pona I, Placheta E, et al: Evolution of the 3-dimensional video system for facial motion analysis: Ten years’ experiences and recent developments. Ann Plast Surg 69:173, 2012 40. Coulson SE, Croxson GR, Gilleard WL: Three-dimensional quantification of the symmetry of normal facial movement. Otol Neurotol 23:999, 2002
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142
CRANIOMAXILLOFACIAL DEFORMITIES/COSMETIC SURGERY
The Impact of Orthognathic Surgery on Facial Expressions Q15
Q2 Q3
Ali Al-Hiyali, BDS, MSc,* Ashraf Ayoub, BDS, MDS, PhD,y Xiangyang Ju,z Mohammad Almuzian, BDS, MSc,x and Thamer Al-Anezi, BMS, BM BCh, BDS, MSck Purpose:
The aim of this pilot study was to evaluate the impact of orthognathic surgical correction of facial asymmetry and maxillary hypoplasia on the magnitude and pattern of facial expressions.
Patients and Methods:
This study was carried out on 2 cohorts of patients: in group 1, 10 patients had surgical correction of facial asymmetry; in group 2, 13 patients had Le Fort I osteotomy to correct maxillary hypoplasia. The patients were asked to perform 3 facial expressions (maximal smile, lip purse, and cheek puff) that were recorded using the Di4D image-capture system before and after surgery. The capture of each expression generated 180 3-dimensional (3D) facial images. Twenty-seven facial soft tissue landmarks were digitized on the first frame of the 3D image of each expression and a mathematical generic mesh was applied on the 3D model to clone each patient’s face. The cloned mesh was superimposed automatically on each sequence of the 3D images to evaluate the pattern of facial expressions. The digitization of facial landmarks was satisfactorily accurate and reproducible.
Results:
In group 1, the asymmetry of facial expressions was significantly decreased after surgical correction (P = .0458). In group 2, Le Fort I osteotomy decreased the magnitude of facial expressions (P = .0267).
Conclusion: Q7
This study confirmed that orthognathic surgery affects the dynamics of facial expressions; this should be considered when planning the surgery and informing patients about the surgical correction of dentofacial deformities. Ó 2015 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg -:1-11, 2015 Facial expressions are the most common means of communication among humans, with 55% of daily social interactions being nonverbal and dependent on facial expressions.1 In addition, dentofacial deformities are associated with compromised facial expressions.2 In living creatures, flawless bilateral facial and body symmetry is a hypothetical concept that rarely exists. Minor asymmetry exists in pleasing-looking faces and does not require treatment. For minor facial asymme-
Q4
try, the right half of the face is frequently wider than the left, with the chin deviated to the left.3 Maxillary hypoplasia combined with relative mandibular excess results in skeletal Class III skeletal deformity; this deformity esthetically affects the attractiveness of the affected individuals. Most patients with Class III skeletal deformity have the appearance of an angry person and they look older than their actual age; therefore, they seek treatment to improve their facial esthetics.4 Maxillary hypoplasia and facial
*Department of Oral and Maxillofacial Surgery, Faculty of
kDepartment of Oral and Maxillofacial Surgery, Faculty of
Medicine, College of Medical, Veterinary and Life Sciences,
Medicine, College of Medical, Veterinary and Life Sciences,
Glasgow University Dental Hospital and School, Glasgow, UK.
Glasgow University Dental Hospital and School, Glasgow, UK.
yProfessor, Department of Oral and Maxillofacial Surgery, College
Address correspondence and reprint requests to Dr Ayoub:
of Medical, Veterinary and Life Sciences, University of Glasgow
Department of Oral and Maxillofacial Surgery, University of Glasgow,
Medical School, Glasgow, UK.
Dental School, 378 Sauchiehall Street, Glasgow G2 3JZ, UK; e-mail:
zSenior Software Engineer, Medical Devices Unit, NHS Greater Glasgow and Clyde; Honorary Research Fellow, Faculty of
[email protected] Received March 11 2015
Medicine, College of Medical, Veterinary and Life Sciences,
Accepted May 13 2015
Glasgow University Dental Hospital and School, Glasgow, UK.
Ó 2015 American Association of Oral and Maxillofacial Surgeons
xFaculty of Medicine, College of Medical, Veterinary and Life
0278-2391/15/00592-3
Sciences, Glasgow University Dental Hospital and School,
http://dx.doi.org/10.1016/j.joms.2015.05.008
Glasgow, UK.
1 FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112
113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168
2
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
asymmetry are among the common facial deformities that are readily correctable with orthognathic surgery.5-8 However, the impact of orthognathic surgery on facial expressions has not been fully investigated. The most common concerns of patients who seek orthognathic surgery are the dysmorphology of facial appearance at rest and with facial expressions. Expressions are dependent on the movement of facial muscles and their relation to underlying bones. Therefore, it is logical to assume that orthognathic surgery will alter the orientation of facial muscles. It also has been suggested that postsurgical stability is dependent on muscle balance and that relapse is more likely if the functional impairments of facial expressions persist after orthognathic surgery.9 Several studies have assessed the impact of orthognathic surgery on the bony structures and the covering soft tissue10-14; however, the impact of orthognathic surgery on the dynamics of facial expressions is rarely investigated.9,15-17 The published studies on this topic have limitations. The direct placement of multiple markers on a patient’s face before image captures can vary between imaging sessions, which introduces inaccuracies into the assessment. Direct application of facial markers also is time consuming for the clinician and requires a high level of cooperation from the patient. Moreover, the application of markers onto the face could prevent the achievement of a natural facial expression.18,19 The small number of landmarks to describe facial movements limits the comprehensiveness of the analysis and the interpretation of the results.17 Various methods have been developed to assess facial expressions,19-21 some of them are 2-dimensional, including photography and videotaping. However, these methods underestimate the magnitude of facial expressions by 43%.22 Facial expressions also have been assessed using 3-dimensional (3D) statistic imaging-based systems.23 However, these methods do not record or analyze the dynamic of facial expressions. The objective assessment of facial muscle movements requires the recording of the associated expressions in a dynamic state. Static capture of maximum facial expressions does not record the direction, speed, and pattern of facial movements, which limits the robustness of the analysis.6 Various 3D dynamic motion-capture systems have been developed recently that are based on active stereophotogrammetry, in which a textured pattern is projected onto the face to aid the 3D build of the facial model,24 or passive stereophotogrammetry, which depends on skin texture to build the 3D facial models.25 The dynamic imaging system captures 60 3D images of the face per second; the capture of each expressions takes approximately 3 seconds, which generates approximately 180 3D facial images for analysis. Facial landmarks are digitized on
the first 3D facial image, and their locations are automatically tracked throughout the sequence of the images of the captured facial expression. The accuracy of the software in tracking the digitized facial landmarks across the sequence of the 3D images of each facial expression captured by a passive stereophotogrammetry imaging system has been validated26 and the clinical application of the method has been tested.27 The purpose of this study was to investigate the impact of orthognathic surgical correction of maxillary hypoplasia and facial asymmetry on facial expressions.
Patients and Methods This study was carried out on 2 cohorts of patients: 10 patients (5 male and 5 female; 17 to 29 yr old) who had surgical correction of facial asymmetry (group 1) and 13 patients (8 female and 5 male; 18 to 50 yr old) who had had Le Fort I osteotomy to address maxillary hypoplasia (group 2). All patients were treated by the same surgeon and followed a standard protocol of data recording and analysis before and after surgery. Preoperative facial expressions were captured 1 week before surgery and 6 to 18 months after surgery (Table 1) using the Di4D capture system (Dimensional Imaging Limited, Glasgow, UK). The system consisted of 2 gray-scale cameras (Model avA 160065km/kc; resolution, 1,600 1,200 pixels; sensor model KAI-02050; Kodak, Basler, Germany), 1 color camera that captured 60 frames per second, and a lighting system (Model DIV-401-DIVALITE; Kino Flo Corporation, Burbank, CA). The system was connected to a personal computer (Win 8.1 professional; Intel Core i7; CPU, 3.40 GHz; RAM, 32.0 GB). The Di4D system was calibrated before each capture session to synchronize the intrinsic camera parameters. The image recording and building of the dynamic 3D imagines were based on passive stereophotogrammetry, which allowed the automatic tracking of facial landmarks throughout the sequence of the captured images of each facial expression. Three nonverbal, reproducible facial expressions were captured in this study, which included maximal smile, lip purse, and cheek puff, according to a previously published protocol.18,20,21 Patients sat in an upright and comfortable position at a 95-cm distance from the cameras. Patients were asked to keep their eyes open and remain relatively still during image capturing. The system’s illumination lights were adjusted by the operator to avoid excessive brightness that could affect the patient’s facial expressions. Three facial expressions were recorded: maximum smile, lip purse, and cheek puff (Fig 1). Ethics approval was granted to conduct this study under the Integrated
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
Q1
169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224
3
AL-HIYALI ET AL
225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280
Table 1. DEMOGRAPHIC DISTRIBUTION OF CASES IN THE 2 GROUPS Q11
Patient Number Group 1 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 Group 2 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13
Age (yr)
Gender
Performed Surgical Procedure
Follow-Up (mo)
20 20 21 20 29 17 19 20 18 18
M M M F F M M F F F
Le Fort I osteotomy + genioplasty BSSO Bimaxillary osteotomy, Le Fort I + BSSO Bimaxillary osteotomy, Le Fort I + BSSO Bimaxillary osteotomy, Le Fort I + BSSO bimaxillary osteotomy, Le Fort I + BSSO Bimaxillary osteotomy, Le Fort I + BSSO Bimaxillary osteotomy, Le Fort I + BSSO BSSO BSSO + genioplasty
5 8 6 6 6 6 5 8 18 18
41 20 20 19 41 19 45 20 49 27 50 18 20
M F F M M F M M F F F F F
Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy Le Fort I osteotomy
6 6 6 6 6 6 6 6 6 6 6 6 6
Abbreviations: BSSO, bilateral sagittal split osteotomy; F, female; M, male. Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
Research Application System GN12DN441 (protocol 1 18) and sponsored by the UK NHS Greater Glasgow and Clyde health board.
DATA PROCESSING
A set of facial landmarks (Table 2) was digitized on the first 3D facial model of each of the 3D sequence of images for each facial expression. The position of these landmarks was tracked automatically across the set of 180 3D sequences of facial images for each expression. To assess the errors of the method, facial soft tissue landmarks of 10 cases were digitized twice, 1 week apart, by the same operator for each of the 3 captured expressions. A novel method was applied to assess the impact of orthognathic surgery on facial expressions using a generic mesh (Fig 2). The generic mesh consists of 1,982 points and was adapted to the morphologic characteristic of the face to generate a confirmed mesh that was specific to each case. The first frame of each 3D sequence for each expression and its related generic mesh were selected for manual digitization of 27 anthropometric facial landmarks (Table 2).28-30 The
landmarks on the first 3D frame were used to clone (transform) a generic mesh to the 3D model in the first frame (Fig 3). The cloned (transformed) mesh was automatically tracked throughout the sequence of the 3D imagining of each expression. The coordinated tracked facial landmarks were saved for statistical analysis.
STATISTICAL ANALYSIS
The analysis of variance (ANOVA) linear mixedeffects (LME) model was applied to test the impact of the orthognathic surgery on the 3 facial expressions at a chosen level of significance (P < .05). The LME model represents a model of a response variable with fixed and random effects. For each fixed-effects term, ANOVA performs a t test to determine whether all coefficients representing the fixed-effects term are equal to 0. Facial asymmetry score and maximal distance changes of facial expressions were analyzed in this study. To investigate the dissimilarity in the shape of lips, cheeks, and chin regions, each 3D facial image was mirror imaged; the reflected image was superimposed on its own original configuration
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
Q12
281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
print & web 4C=FPO
337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392
4
FIGURE 1. Three-dimensional image sequence of the captured maximum smile before surgical correction. All expressions were captured from Q10 rest to maximum positions. Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
(shape) using partial Procrustes analysis (PPA). The process of mirror reflection of each 3D image was based on the equation x = x x(1), which allowed the entire set of 3D images to be ‘‘mirrored’’ around the x axis to obtain a mirror-like reflection. PPA allowed the maximum superimposition of corresponding shapes by transformation (rotation without scaling). PPA was applied in this study to maintain the original sizes of the tested regions (lips, cheeks, and chin). PPA allowed the values of the differences between the original and mirror-reflected 3D images to be measured as the sum of squared distances of the corresponding vertices, which represented the asymmetry score in each 3D facial image. The average scores from at rest to maximal expression measured the asymmetry of the facial movements. An ANOVA LME model was applied to test the impact of surgery on the asymmetry scores of facial expressions as a fixed effect and the types of facial expression and gender as random effects. The 3 recorded facial expressions were amalgamated together and analyzed collectively to evaluate the impact of orthognathic surgery on these facial movements. The scores obtained from the PPA were tested using the ANOVA LME model to generate the facial asymmetry score. This protocol was applied for each sequence of facial expressions that were recorded before and after surgery for each case in the 2 groups. The method also was applied to measure the differences of the vertices in the lips, cheeks, and chin regions. Differences in the magnitude of maximal expressions were investigated in this study. The tracked
coordinates of facial landmarks were used to assess the magnitude of maximal movement for each of the recorded facial expressions before and after surgery. The change from the rest position (first 3D frame of facial expression) to maximal expression (peak 3D frame of the same facial expression) was tracked and calculated using correspondence analysis (CA). CA is a statistical method based on mapping the difference between 2 facial confirmed meshes. The obtained CA scores were analyzed by the ANOVA LME model to assess the impact of orthognathic surgery on the magnitude of facial expressions.
Results ERRORS OF THE METHOD
The mean differences among the repeated landmark procedures of the 3D facial images were 0.1, 0.2, and 0.6 mm in the x, y, and z directions, which confirmed that the landmark technique was accurate and reproducible. GROUP 1 (SKELETAL FACIAL ASYMMETRY)
There was a significant difference in facial expression asymmetry scores as a result of the surgical correction (P = .0458; Fig 4). The improvement in the symmetry of facial expressions for this group of patients is illustrated in the color mapping of Figure 5, which shows the degree of deference between the Q8 2 surface meshes by a color scale graded in millimeters.
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448
5
AL-HIYALI ET AL
449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504
Table 2. NAMES AND DEFINITIONS OF LANDMARKS THAT WERE DIGITIZED ON THE 3-DIMENSIONAL IMAGE
Landmark Number Q13
Landmark Name
1 and 5
Exocanthion
2 and 4
Endocanthion
3
Glabella
6 and 8 7
Superciliary points Nasion
9
Pronasale
10
Subnasale
11
Labrale superius
12
Labrale inferius
13 14 and 19
Pogonion Zygion
15 and 20
Alar curvature
Q6
16 and 21
Subalare
Q5
17 and 22 18 and 23 24 and 25
Crista philter Cheilion Right and left upper middle lateral lip points Right and left lower middle lateral lip points
Q14
26 and 27
Description Point at the outer commissure of the eye fissure, located slightly medial to the bony exocanthion Point at the inner commissure of the eye fissure, located lateral to the bony landmark Most prominent midline point between the eyebrows, identical to the bony glabella on the frontal bone Points located above the most superior aspects of the eyebrows Point in the midline of the nasal root and the nasofrontal suture, always above the line that connects the 2 inner canthi; identical to the bony nasion Most protruded point of the nose identified in the lateral view of the rest position of the head Midpoint of angle at the columella base where the lower border of the nasal septum and the surface of the upper lip meet Point indicating maximum convexity of the mucocutaneous junction of the upper lip and philtrum Point indicating maximum convexity of the mucocutaneous border of the lower lip Most anterior midpoint of the chin Most prominent point on the cheek area beneath the outer canthus and slightly medial to the vertical line passing through it; different from the bony zygion Most lateral point on the curved base line of each ala, indicating the facial insertion of the nasal wing base Point on the margin of the base of the nasal ala where the ala disappears into the upper lip skin Peak of cupid’s bow of the upper inferior point located at the corner of each labial commissure Midpoints located between the cheilion and labrale superius
Midpoints located between the cheilion and labrale inferius
Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
There was no significant difference in the magnitude of facial expression as a result of orthognathic surgical correction of asymmetry (P = .1984; Fig 6); the differences in the maximal distance of facial expressions are shown by color mapping (Fig 5). The measured distance was recorded between the 3D facial image of first frame of capture (rest position) and the 3D image at maximal peak (maximum expression).
GROUP 2 (MAXILLARY HYPOPLASIA)
Changes in the symmetry of facial expressions as a result of Le Fort I osteotomy were not significant (P = .6994; Fig 7). There was a significant difference in the magnitude of facial expressions before and after surgery (P = .0267; Fig 8); the differences are presented by the color mapping illustrations (Fig 9). The measured
distance was between the first 3D image (rest position) and the peak 3D image (maximum expression).
Discussion Facial expressions have an impact on the diagnosis of facial soft tissue impairments, planning of the surgical correction, and assessment of surgical outcomes.27,31 Therefore, it is important for clinicians to evaluate the dynamics of facial expressions before the surgical planning for the correction of skeletal deformities. It also is valuable to evaluate the changes in the pattern and magnitude after orthognathic surgery, which can affect the stability of the achieved results.6,9,16,17 Various 3D dynamic motion analysis systems have been used for the assessment of facial expressions. These systems track markers on the face or track pixels of the facial images. These systems have been
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560
print & web 4C=FPO
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
FIGURE 2. Generic mesh used to evaluate the dynamic changes of facial expressions. Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
used to assess facial expressions,2,30-36 after nonorthognathic surgical procedures, and to quantify the symmetry of normal facial movements.23,28,37-40 The first video-based study to investigate the impact of orthognathic surgery on facial expressions was
conducted on 19 patients.9 Eleven patients had skeletal Class II mandibular retrognathia, 5 patients had anterior open bite, and the other 3 patients had skeletal Class III maxillomandibular relation. A set of 34 spherical, retroreflective markers, 2 mm in diameter, were attached by eyelash adhesive to specific anthropologic landmarks on the patients’ faces, and facial expressions were recorded by a video-based tracking system (Motion Analysis; Motion Analysis Corporation, Santa Rosa, CA). Seven facial animations were performed by each patient, including the instructed maximal smile, lip purse, mouth opening, cheek puff, eye opening, eye closure, grimace, and a natural smile animation. The aim was to measure the relative change or percentage of change in distance from rest to maximal animation between corresponding pairs of landmarks. There was a statistical difference in the magnitude of animations after surgery, with the most important changes detected in the lip purse animation. These findings suggested that facial movements are affected by skeletal malocclusion and orthognathic surgical procedures. The results showed that all changes were related to the direction of the facial expressions and these varied for each patient group in the study. However, the symmetry and magnitude of facial expressions were not assessed. A 3D laser scanner was used to assess the effect of orthognathic surgery on facial expressions16 in 11 cases that required orthognathic surgery. Only 13 landmarks were directly placed on the patients’ faces before capturing 5 basic facial expressions (frowning, eye closure, grimace, smile, and lip purse). The facial images were captured at 1 week before surgery and
print & web 4C=FPO
561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616
6
FIGURE 3. Transformed mesh (generic mesh) to track the changes of anatomic landmarks throughout the sequence of 3-dimensional capture during facial expressions (patient from facial asymmetry group). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672
7
FIGURE 4. Boxplot showing changes in the asymmetry score of facial expressions after surgery (group 1). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
at 3, 6, and 12 months postoperatively. The displacement of every landmark at specific intervals was investigated. A change in the symmetry of facial expressions as a result of surgery was detected. At 1-year follow-up, the magnitude of facial movements was statistically similar to that recorded before surgery. The path of
movement of facial landmarks was not tracked and the results were based only on the positional differences between rest and maximum expression. The landmarks-based analysis has limitations, and the anatomic areas between the landmarks were not considered in this study. The direct placement of multiple markers on the face before image capture is a major obstacle for the assessment of facial expressions. This can vary between sessions and among operators, which contributes to the errors of the method and affects the reliability of the assessment. Direct marker placement also is time consuming for the patient and the clinician and could prevent the patient from producing a natural facial expression.18,19 The applied generic mesh in the present study was an innovation in assessing the impact of orthognathic surgery on facial expressions. The confirmed mesh is considered a fingerprint that captures facial patterns and morphologic characteristics of each patient’s face. The 27 landmarks that were digitized on the 3D facial model in this study were used only to guide the cloning of the facial mesh for the transformation process of the generic mesh to produce the confirmed mesh. The application of the confirmed meshes in the
print & web 4C=FPO
673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728
print & web 4C=FPO
AL-HIYALI ET AL
FIGURE 5. Illustration of the change of symmetry of the maximum smile after surgery shown on photorealistic images and color-coded facial masks (group 1). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784
print & web 4C=FPO
print & web 4C=FPO
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
FIGURE 6. Boxplot showing changes in maximal distance of facial expressions after surgery (group 1). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
tracking process allowed the automatic tracking of up to 3,000 anatomic corresponding ‘‘vertices’’ that improve the accuracy and comprehensive nature of the morphometric analysis. In this study, only the lips, cheeks, and chin regions were analyzed, because these were the anatomic regions most affected by the captured facial expressions. The confirmed mesh of the 3 anatomic regions contained 469 facial points for analysis and tracking of facial expressions. The results showed that in asymmetric cases there was a statistical difference in asymmetry scores between preoperative and postoperative facial expressions. Orthognathic surgical correction of facial asymmetry improved the associated asymmetry of facial muscle movements. Surgery produced more balance to the dynamics of the movements of the attached facial muscles and the related expressions.
print & web 4C=FPO
785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840
8
FIGURE 7. Boxplot showing changes in asymmetry score of facial expressions after surgery (group 2). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
FIGURE 8. Boxplot showing changes in maximal distance of facial expressions after surgery (group 2). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
Orthognathic correction of the facial bones led to repositioning of the muscles, fat, and associated skin in a more symmetric position. This positional change of the muscle attachments might have resulted in changing the direction and magnitude of facial expressions. The indirect effect of surgery is on the proprioception and motor activity of the muscles of facial expressions, especially those of the lips, cheeks, and chin regions. This would contribute to the changes in the direction and magnitude of facial expressions. The authors acknowledge the heterogeneity of the sample of asymmetric cases regarding the surgical approach for the correction of the underlying asymmetry. However, the common denominator in all cases was the asymmetry of facial expressions. The performed surgery, Le Fort I osteotomy or sagittal split osteotomy, changes the orientation of the orbicularis oris muscle and other muscles of facial expressions, improving the symmetry of facial movements. The main objective of this study was the evaluation of the dynamic and magnitude of facial expressions before and after surgery. The sample is too small to correlate the magnitude of the surgical movements with the observed changes in the pattern and magnitude of facial expressions. In addition, the thickness of the soft tissue was not measured in this study owing to the lack of a standardized protocol and a reliable method for this measurement. To the authors’ knowledge, there is no evidence in the literature to show a clear correlation between tissue thickness and the dynamics of facial expressions. In group 2, the physiologic explanation of the statistical difference in the magnitude of animations could be due to the fact that Le Fort I maxillary advancement stretches the attachments of the muscles of facial
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896
9
897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952
print & web 4C=FPO
AL-HIYALI ET AL
FIGURE 9. Illustration of the change of the symmetry of the maximum smile after surgery shown on photorealistic images and color-coded facial masks (group 2). Al-Hiyali et al. Orthognathic Surgery and Facial Expressions. J Oral Maxillofac Surg 2015.
expressions. These findings are complementary to a previous study that showed that mandibular setback surgery increases the magnitude of lip movements,9 which produces the opposite effect of Le Fort I maxillary advancement on the attachment of the lip muscles. The latter will cause stretching of the attached muscles to the maxilla, and this might have contributed to the decreased magnitude of lip movements. However, the long-term impact of maxillary advancement on lip movement was not examined in this study and warrants further investigation.
It is likely that the magnitude of surgical movement would influence the change in facial expressions; however, owing to the small sample, the evaluation of the relation between surgical movements and the change in the pattern of facial expressions has limited value in this study. A longer follow-up is highly desirable; it might show that the magnitude of facial expressions gradually returns to its preoperative measurement. However, patients should be warned of the expected restriction in facial expressions during the first 6 months after surgery. A larger sample would lend
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064
10
Q9
ORTHOGNATHIC SURGERY AND FACIAL EXPRESSIONS
itself to a more intensive analysis on the relation between skeletal jaw movements and the change in the dynamic of facial expressions. Another limitation of this study is the amalgamation of the 3 facial expressions for the analysis of the impact of orthognathic surgery on muscle movements. One could argue that the changes of one expression in one direction cancel the changes of another expression in an opposite direction. A larger sample would have allowed the study of the impact of orthognathic surgery on each facial expression separately and a more robust conclusion on understanding the relation between the surgical movements of the osteotomy segments and the attached muscles. This study did not investigate the relation among the extent of surgery, 1- or 2-jaw surgery, the magnitude and direction of movements of the osteotomy segments (yaw, pitch, and roll), and the recorded changes in facial expressions. A larger sample would be required to answer these questions. Nevertheless, the study shows clearly the impact of orthognathic surgery on the magnitude and overall symmetry of facial expressions. The authors hope this study inspires a more comprehensive investigation on a more homogenous group of orthognathic cases. They acknowledge this article does not provide the answers to all these questions; it is just the first step in highlighting the importance of investigating the dynamics of facial expressions and evaluating the impact of orthognathic surgery on the symmetry and magnitude of these movements. Correction of facial asymmetry improved facial symmetry. The magnitude of facial expressions was decreased after Le Fort I osteotomy. The asymmetry score developed in this study is a novel and sensitive tool in quantifying facial expressions that could have a broad clinical application in the assessment of facial muscle movements.
References 1. Mehrabian A: Inference of attitudes from nonverbal communication in two channels. J Consult Psychol 31:248, 1967 2. Weeden JC, Trotman CA, Faraway JJ, et al: Three dimensional analysis of facial movement in normal adults: Influence of sex and facial shape. Angle Orthod 71:132, 2001 3. Cheong YW, Lo LJ: Facial asymmetry: Etiology, evaluation, and management. Chang Gung Med J 34:341, 2011 4. Posnick JC: Orthognathic Surgery: Principles and Practice. New York, NY, Elsevier, 2014, pp 686–757 5. Proffit WR, Turvey TA, Phillips C: Orthognathic surgery: A hierarchy of stability. Int J Adult Orthodon Orthognath Surg 11:191, 1996 6. Johns FR, Johnson PC, Buckley MJ, et al: Changes in facial movement after maxillary osteotomies. J Oral Maxillofac Surg 55: 1044, 1997 7. Bauer RE, Ochs MW: Maxillary orthognathic surgery. Oral Maxillofac Surg Clin North Am 26:523, 2014 8. Severt TR, Proffit WR: The prevalence of facial asymmetry in the dentofacial deformities population at the University of North Carolina. Int J Adult Orthodon Orthognath Surg 12:171, 1996
9. Nooreyazdan M, Trotman CA, Faraway JJ: Modeling facial movement: II. A dynamic analysis of differences caused by orthognathic surgery. J Oral Maxillofac Surg 62:1380, 2004 10. Katsumata A, Fujishita M, Maeda M, et al: 3D-CT evaluation of facial asymmetry. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 99:212, 2005 11. Trpkova B, Prasad NG, Lam EW, et al: Assessment of facial asymmetries from posteroanterior cephalograms: Validity of reference lines. Am J Orthod Dentofacial Orthop 123:512, 2003 12. Yamamoto M, Takaki T, Shibahara T: Assessment of facial asymmetry based by subjective evaluation and cephalometric measurement. J Oral Maxillofac Surg Med Pathol 24:11, 2012 13. Forsberg CT, Burstone CJ, Hanley KJ: Diagnosis and treatment planning of skeletal asymmetry with the submental-vertical radiograph. Am J Orthod 85:224, 1984 14. Bishara SE, Burkey PS, Kharouf JG: Dental and facial asymmetries: A review. Angle Orthod 64:89, 1994 15. Wachtman GS, Cohn JF, VanSwearingen JM, et al: Automated tracking of facial features in patients with facial neuromuscular dysfunction. Plast Reconstr Surg 107:1124, 2001 16. Verze L, Bianchi FA, Dell’Acqua A, et al: Facial mobility after bimaxillary surgery in Class III patients: A three-dimensional study. J Craniofac Surg 22:2304, 2011 17. Popat H, Richmond S, Marshall D, et al: Three-dimensional assessment of functional change following Class 3 orthognathic correction—A preliminary report. J Craniomaxillofac Surg 40: 36, 2012 18. Sawyer AR, See M, Nduka C: Assessment of the reproducibility of facial expressions with 3-D stereophotogrammetry. Otolaryngol Head Neck Surg 140:76, 2009 19. Frey M, Giovanoli P, Gerber H, et al: Three-dimensional video analysis of facial movements: A new method to assess the quantity and quality of the smile. Plast Reconstr Surg 104: 7, 1999 20. Johnston DJ, Millett DT, Ayoub AF, et al: Are facial expressions reproducible? Cleft Palate Craniofac J 40:291, 2003 21. O’Leary E, Ju X, Khambay B, et al: Evaluation of the reproducibility of non-verbal facial animations. Lecture Notes Comput Sci 7378:184, 2012 22. Gross MM, Trotman CA, Moffatt KS: A comparison of threedimensional and two-dimensional analyses of facial motion. Angle Orthod 66:189, 1996 23. Hajeer MY, Ayoub AF, Millett DT: Three-dimensional assessment of facial soft-tissue asymmetry before and after orthognathic surgery. Br J Oral Maxillofac Surg 42:396, 2004 24. Popat H, Richmond S, Benedikt L, et al: Quantitative analysis of facial movement—A review of three-dimensional imaging techniques. Comput Med Imaging Graph 33:377, 2009 25. Mishima K: Analysis methods for facial motion. Jpn Dent Sci Rev 45:4, 2009 26. Al-Anezi T, Khambay B, Peng MJ, et al: A new method for automatic tracking of facial landmarks in 3D motion captured images (4D). Int J Oral Maxillofac Surg 42:9, 2013 27. Shujaat S, Khambay BS, Ju X, et al: The clinical application of three-dimensional motion capture (4D): A novel approach to quantify the dynamics of facial animations. Int J Oral Maxillofac Surg 43:907, 2014 28. Farkas L: Anthropometry of the Head and Face (ed 2). New York, NY, Raven Press, 1994, pp 79–88 29. Sawyer AR, See M, Nduka C: Quantitative analysis of normal smile with 3D stereophotogrammetry—An aid to facial reanimation. J Plast Reconstr Aesthet Surg 63:65, 2010 30. Hajeer MY, Ayoub AF, Millett DT, et al: Three-dimensional imaging in orthognathic surgery: The clinical application of a new method. Int J Adult Orthodon Orthognath Surg 17: 318, 2002 31. Trotman CA: Faces in 4 dimensions: Why do we care, and why the fourth dimension? Am J Orthod Dentofacial Orthop 140: 895, 2011 32. Popat H, Richmond S, Playle R, et al: Three-dimensional motion analysis—An exploratory study. Part 1: Assessment of facial movement. Orthod Craniofac Res 11:216, 2008
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120
11
AL-HIYALI ET AL
1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131
33. Popat H, Richmond S, Zhurov AI, et al: A geometric morphometric approach to the analysis of lip shape during speech: Development of a clinical outcome measure. PLoS One 8: e57368, 2013 34. Mishima K, Yamada T, Matsumura T, et al: Analysis of lip motion using principal component analyses. J Craniomaxillofac Surg 39: 232, 2011 35. Trotman CA, Faraway JJ: Sensitivity of a method for the analysis of facial mobility. II. Interlandmark separation. Cleft Palate Craniofac J 35:142, 1998 36. Trotman CA, Faraway JJ: Modeling facial movement: I. A dynamic analysis of differences based on skeletal characteristics. J Oral Maxillofac Surg 62:1372, 2004
37. Trotman CA, Faraway JJ, Phillips C: Visual and statistical modeling of facial movement in patients with cleft lip and palate. Cleft Palate Craniofac J 42:245, 2005 38. Hontanilla B, Auba C: Automatic three-dimensional quantitative analysis for evaluation of facial movement. J Plast Reconstr Aesthet Surg 61:18, 2008 39. Tzou CH, Pona I, Placheta E, et al: Evolution of the 3-dimensional video system for facial motion analysis: Ten years’ experiences and recent developments. Ann Plast Surg 69:173, 2012 40. Coulson SE, Croxson GR, Gilleard WL: Three-dimensional quantification of the symmetry of normal facial movement. Otol Neurotol 23:999, 2002
FLA 5.2.0 DTD YJOMS56816_proof 1 June 2015 8:52 pm CE AH
1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142
