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CLINICIANS'CORNERThe accuracy of video imaging inorthognathic surgeryPeter M. Sinclair, DDS, MSD, a Pauli Kilpelainen, DDS, b Ceib Phillips, PhD, MPH, Raymond P. White, Jr., DDS, PhDfl Lyna Rogers, RDH, BS, e and David M. Sarver, DMD, MS fChapel Hill, N.C.Video imaging is an important emerging technology in planning orthognathic surgery and educatingpatients about the esthetic effects of treatment. The presurgical cephalograms of 56 patients, 41with mandibular advancement alone and 15 with mandibular advancement plus genioplasty, weredigitized, and the computer-generated soft tissue "line drawing" predictions were compared withthe actual postt(eatment cephalograms. Video images of the patients' presurgical lateral view wereobtained, and two experienced clinicians compared the computer generated video imagepredictions with the actual posttreatment profile. Video images judged very good or excellent wereconsidered acceptable for treatment planning; 60% to 83% met this criterion, depending on theprofile area viewed. The percentage of acceptable images in the lower lip, labiomental fold, andchin area decreased with the addition of a genioplasty. The predicted and actual posttreatment softtissue line drawings were quite similar for all areas except for the lower lip region, where statisticallysignificant differences were noted, with the predicted lower lip more retrusive and thinner than theactual contours. For the lower lip and chin, a 2 mm or more discrepancy was observed in 20% ofthe patients. In all cases, the actual image was judged more esthetic than the predicted image,allaying fears of unrealistically optimistic computer generated predictions. (AM J ORTHODDENTOFACORTHOP1995;107:177-85.)Withover 70% of prospective orthognathic surgery patients citing esthetics as a motivator for seeking treatment, 1 there is clearly a needfor a treatment prediction technique that gives theclinician the diagnostic information required toplan treatment accurately, while also providing patients with a realistic simulation of the estheticoutcomes of their treatment. Currently, there arethree methods by which orthognathic treatmentoutcomes can be predicted by using lateral cephalometric radiographs.The first method, most commonly used for thepast 20 years, involves manually repositioning acetate tracings of skeletal segments over the originalSupported in part by NIH grant DE-05215 from the National Institute ofDental Research, and by the Dental Foundation of North Carolina."Professor and Chairman, Department of Orthodontics, University ofSouthern California, Los Angeles.bFaculty of Dentistry, Department of Orthodontics, University of Kuopio,Kuopio, Finland. Associate Professor, Orthodontic Department, University of NorthCarolina.dProfessor, Department of Oral and Maxillofacial Surgery, University ofNorth Carolina. Research Associate, Orthodontic Department, University of NorthCarolina.fAdjunct Professor, University of North Carolina; private practice, Birmingham, Ala.Copyright 1995 by the American Association of Orthodontists.0889-5406/95/ 3.00 0 8/1/53318cephalometric tracing to simulate the proposedtreatment. 2 The posttreatment soft tissue outline isthen added based on accepted ratios of soft tissueto hard tissue changes. This approach suffers fromtwo major weaknesses: (1) the variables of softtissue thickness, tonicity, individual patient response, as well as differences in the surgeon's softtissue manipulation introduce uncertainties thatmake the soft tissue prediction as much an art formas a science; and (2) the "line drawing" of the softtissue, while relatively informative to the clinician,often does not provide the patient with an adequate image of the proposed result.In the second technique, appropriate landmarksfrom the cephalometric tracing are digitized andentered into a computer. 3-6 Surgical movements aresimulated on the screen and the treatment optionscompared. Hard copies of each option serve asvisual aids in discussions with the patient. Manipulating the image by computer, however, is no moreaccurate than doing a prediction by hand, since thepredictions are based on the same guidelines usedin manual predictions. Although the provision ofhard copies of several options for discussion withthe patient may facilitate communication, they arestill line drawings and do not provide a lifelikeesthetic representation of the predicted outcome.177

178Sinclair et al.Fig. 1. Cephalometric superimposition showing actual postsurgical tracing (dotted line) and computer generated prediction (solid line).The third prediction technique involves blending the digitized image of the lateral cephalometrictracing with a video image of the patient. 7- 1 Theorthodontic and surgical predictions producedfrom the digitized cephalometric tracing are combined with the video image, so that the predictionincludes both a line drawing and a correspondingfacial image. Images of treatment options can thenbe displayed on the computer terminal, or a hardcopy can be produced.Video imaging offers two significant advantagesover previous prediction techniques. First, the predicted image facilitates communication betweendoctor and patient by establishing visual treatmentgoals for orthodontics and surgery. This addressesthe patient's basic "need to know" and, by involving the patient in the selection of the treatmentoptions, should improve patient acceptance of theoutcome. 7'8 By patients developing joint goals withtheir doctors, clinicians with experience in videoimaging report that there are fewer surprises, fewerunrealistic expectations, and a greater "bonding"between doctor and patient during treatment.The second suggested advantage of video imag-American Journal of Orthodontics and Dentofacial OrthopedicsFebruary 1995ing relates to its ability to aid in treatment planningdecisions. 9-11 It provides the orthodontist and surgeon with a manipulable image so a consensusdecision can be made on the desired soft tissueoutcome. For example, the esthetic improvement ofcorrecting a Class III malocclusion by advancingthe maxilla can be compared with setting back themandible. Video imaging can also be particularlyhelpful in deciding whether or not to performadjunctive soft tissue procedures? 2 The advantageof having an actual facial image to review andmanipulate rather than just a "line drawing" orcutting up enlarged photographs to perform "photograph surgery" is particularly important whenattempting to meet the patient's principal facialesthetic concerns.The questions regarding video imaging revolvearound several issues. First, does the presentationof an image to a patient create an unrealisticexpectation of the final result? Does sharing theimage with the patient represent an implicit warranty as to the treatment outcome? In addition, canthe surgeon actually produce the suggested outcome, or is the video image simply the resultcreated by a skilled computer operator? 7 Some ofthese questions regarding patient expectations ofvideo imaging were addressed by Sarver et al. 8Their findings showed that 89% of the patientsbelieved that the image predictions were realisticand the desired results were achieved. In theirsample, 83% of the patients believed that theimaging process was beneficial in helping themmake their decision whether or not to have surgery,and 72% believed that the imaging process allowedtheir participation in specific treatment decisions.The fear that a patient's expectations might become too great if provided a presurgical videoprediction did not appear to be supported. Incomparison, Kiyak's studies show that less than45% of patients from a nonimaged populationexpressed esthetic satisfactionJ This would supportthe contention that patients who have been imagedhave more realistic expectations as to treatmentoutcome, and therefore the chances of dissatisfaction are reduced considerably.A major concern regarding video imaging centers on the accuracy of the prediction. Is it trulyreflective of the probable outcome, too optimisticor too pessimistic? Are specific areas of the image,i.e., lips and chin, accurate enough only for displayto the patient as a rough guideline, or can they beused as specific templates from which to plan theorthodontic and surgical movements.

American Journal of Orthodontics and Dentofacial OrthopedicsVolume 107, No. 2Sinclair et aL179Table h Difference between actual and predicted line drawing soft tissue valuesDiscrepancyX SDRangeP value - 2 m m (percent) 2 m m (percent)Upper lipUpper lip-SNV (ram)Upper lip--E-plane (ram)Upper lip-hard tissue(ram)Upper l i p - U I labia 1 surface (mm)Subnasale-stomion (ram)Superior labial sulcus - SNV(mm)-0.10 1 . 1 2-0.39 - 1 . 7 2 0.00 - 1 . 5 8-3.0/ 3.2-4.4/ 4.2-4.3/ 5.00.490.090.9952011022-0.07 - 1 . 5 7-4.3/ 4.90.7182-0.40 - 1 . 8 6 0.04 - 0.70-4.1/ 5.0- 1.5/ 1.90.110.6221020-0.76 2 . 0 5-1.22 - 2 . 1 8-0.86 - 1 . 7 6-5.2/ 4.5-7.1/ 3.7-5.5/ 4.40.010.00010.001303224202-0.84 1 . 8 0-6.3/ 4.90.001252 0.39 - 3 . 3 8-9.3/ 11.440.381810 0.44 0.01 0.57 0.13-5.2/ 4.5-5.4/ 11.0-6.9/ 6.5-4.0/ 6.00.070.990.150.5047241566207 0.40 - 1.91-4.5/ 6.70.1l1110-0.19 - 2 . 1 9 0.27 - 2 . 1 9-5.8/ 7.0-5.8/ 7.00.500.35181564Lower lipLower lip-SNV line (mm)Lower lip-E-plane (ram)Lower lip-hard tissue(mm)Lower l i p - L I labial surface (mm)Stomion-ILS (mm)ChinILS-SNV (ram)Pgs-SNV (ram)I L S - M e (ram)Pogonion (soft) to hardtissueSoft to hard tissue Me(ram)Pogonion to soft Pg (ram)Menton to soft Me (ram)- 1.83- 2 . 3 2- 2 . 9 8- 2 . 1 7- indicates prediction value smaller or more retrusive than actual value. indicates prediction values larger or more protrusive than actual value.These questions regarding the accuracy of videoi m a g i n g have y e t to b e scientifically i n v e s t i g a t e da n d t h e r e f o r e l e d to t h e s e two r e s e a r c h questions:( l ) Is t h e v i d e o i m a g e a c c u r a t e a n d realistic e n o u g hto u s e in p r e s e n t a t i o n to p a t i e n t s ? a n d (2) A r especific a r e a s of t h e i m a g e a c c u r a t e e n o u g h for usein t r e a t m e n t p l a n n i n g and, if different, in w h a t w a ya n d why? This s t u d y a d d r e s s e s t h e s e questions.MATERIALS AND METHODSThe sample used in this study consisted of 56 patientsdrawn from the office of one of the authors (D.S.), whohad completed treatment involving orthodontics and orthognathic surgery to advance the mandible a minimumof 5 mm. Forty-one patients underwent a mandibularadvancement only, whereas the remaining 15 patientshad an additional advancement genioplasty. All the patients were over 18 years of age, white, and selected onthe basis of the availability of presurgical and posttreatment lateral cephalograms and lateral profile photographs. All records were taken with teeth together incentric occlusion, and the lips in repose.The presurgical and posttreatment cephalogramswere digitized with the Prescription Planner/Portraitsoftware program (Rx Data Inc, Ooltewah, Tenn.), and acranial base superimposition was performed. The actualamounts of anteroposterior and vertical surgical changethat had occurred during treatment was measured at thelower incisor tip, B point, pogonion, and menton. Withthese values, a line drawing profile prediction was generated from the presurgical cephalogram. The hard tissue cephalometric prediction was then superimposed onthe digitized posttreatment hard tissue cephalogram.Thus, with the computerized hard tissue prediction andthe actual hard tissue final result superimposed, it waspossible to compare and analyze the line drawing cephalometric soft tissue outlines (i.e., the actual final softtissue outline versus the predicted soft tissue outline) todetermine the accuracy of the soft tissue line drawingprediction (Fig. 1).With a special soft tissue analysis module of thesoftware program developed for this project, 18 linear orangular soft tissue measures (Table I) on the upper lip,lower lip, and chin were obtained on the digitized posttreatment cephalogram and on the prediction line draw-

180Sinclair et al.AmericanJournalof Orthodonticsand DentofacialOrthopedicsFebruary 1995Fig. 2. A, Presurgical video image with computer generated postsurgical predicted cephalometricline drawing superimPosed on it. B, The resultant computer generated surgical video imageprediction for this patient.ing. The differences between the actual posttreatmentsoft tissue and the predicted posttreatment soft tissue"line drawing" were analyzed with paired t tests. Thedifference in the discrepancies observed in the twosurgical groups was compared with unpaired t tests.Errors in the soft tissue of the predicted line drawing willbe reflected in the predicted video image since the imageis based on the predicted line drawing. Level of significance was set at 0.01 because of the number of analysesperformed.Video images of the patient's presurgical and posttreatment lateral facial photographs were captured witha CCD-F33 camera (Sony Corp., Tokyo, Japan) set at astandardized distance with uniform background lighting,and displayed on a flat screen RGB monitor using thePrescription Portrait software program. The predictedposttreatment line drawing was overlayed on the presurgical video image and a predicted posttreatment videoimage generated (Fig. 2). All the predictions were created without the computer operator employing any of thesmoothing and blending functions available in the program. Although these functions can improve the prediction image, the use of these functions is subjective andmay vary from patient to patient.To assess whether the video image predictions wereaccurate and representative enough to display to patients, the actual initial, actual final, and predicted finalvideo images of one patient at a time were simultaneously displayed on the monitor (Fig. 3). These threeimages were evaluated and scored independently by anoral surgeon (R.W.) and an orthodontist (P.S.) for howwell the predicted final image matched the actual finalimage. Both clinicians, who had been in clinical practicefor at least 10 years, were full-time faculty members andteam members in the Dentofacial Deformity clinicthrough which potential surgical-orthodontic treatmentpatients are evaluated. Neither clinician had been involved in any aspect of treatment for these 56 patients.The clinician's perception of the concordance betweenthe actual posttreatment and predicted video images wasevaluated by using the following 5-point scale:0: Poor-little agreement between predicted and actualimages1: Fair-general form of prediction acceptable but notclinically representative2: Good-predicted image clinically representative butwith noticeable (by any observer) differences fromactual image3: Very good-predicted image clinically accurate withonly minor (only noticeable by a trained clinician)differences from actual image4: Excellent-predicted image indistinguishable from actual imageThe clinicians discussed the use of the scale beforescoring began but no formal calibration session was held.Perceptual assessments were made at the upper lip,lower lip, labiomental fold, chin, and submental areas.Small differences (one scale unit) occurred frequently between the examiners, resulting in low intraclass correlation values. Rho values ranged from 0.32 forthe upper lip to 0.53 for the labiomental fold. However,a difference of two scale units occurred in only 4% of the

American Journal of Orthodontics and Dentofacial OrthopedicsVolume 107, No. 2Sinclair et al.181Fig. 3. Representation of actual presurgical image, computer generated postsurgical prediction, andactual postsurgical video image (left to right) as displayed on screen for evaluation.patients for the upper lip and in only 12% for the leastconsistent point, the labiomental fold. There were nodifferences of three scale units. Because of the lowproportion of major discordances between the two observers bat the low exact agreement, the sum of the twoobserver's scores for each area was used as the outcomemeasure. The Mantel Haenszel row mean score test wasused to compare the predictive utility of the areas of theface between the mandibular advancement with andwithout genioplasty groups and the Mantel Haenszel testfor matched designs, the equivalent to the Cochran's Qcriterion for measures with more than two responses, wasused to compare the predictive utility for the areas onthe face. 13RESULTSActual versus predicted line drawingsBecause the average discrepancies for the genioplasty group were not statistically different(p 0.03) from those of the mandibular advancement alone group, the data were combined foranalysis. Differences between actual and predictedmeasures on the posttreatment soft tissue profileare shown in Table I. As the table shows, the m e a ndifference between actual and predicted was quitesmall for measures other than those of the lowers lip and were not statistically significant. For thelower lip, the differences between actual and predicted are statistically significant at the 0.01 level.The computer predicted lip was found to be significantly (p 0.01) m o r e retrusive when com-pared with both the E-line and a vertical linedropped through subnasale (SNV-line). The lowerlip was also predicted to be considerably thinner(p 0.01) than was actually the case, both in thearea of B point and overlying the lower incisor. Thepredicted length of the lower lip as measured fromstomion to inferior labial sulcus, however, was notsitgnificantly different from the real outcome.Since the average can mask differences in thedistribution of discrepancies, the percentage of thepatients with a difference of 2 m m or more between actual and predicted line drawings also isshown in Table I. For 11 of the 18 measures, a2 m m or greater discrepancy was noted in at least20% of the patients. Note that the percentage withdifferences at chin points is higher than might havebeen expected from the m e a n changes alone. Inpart, this is due to the genioplasty patients whosechanges at the chin were not as consistent as thenongenioplasty group. For all the measures exceptthe inferior labial sulcus depth, the percentage ofpatients for whom the 2 m m discrepancy was an"under prediction" exceeded the "over prediction"percentage.Actual versus predicted video imagesD a t a for the judgment of the video images bythe two clinicians are shown in Tables I! and III.For the mandibular advancement only group, thepredicted images were perceived as agreeing with

182Sinclair et aLAmerican Journal of Orthodontics and Dentofacial OrthopedicsFebruary 1995Table II. Accuracy of video imaging predictions for mandibular advancement patients (n 41)ScaleArea evaluated0 Poor1 Fair2 Good3 Very good4 Excellent5 Clinically acceptable(3 and 4 combined)Upper lipLower lipLabiomental foldChinSubmental 9%39%32%32%23%22%21%83%71%62%71%60%Percentage of patients showing: O: Poor-little agreement between predicted and actual images; 1: Fair-general form of predictionacceptable but not clinically representative; 2: Good-predicted image clinicallyrepresentative but still not with noticeable (by anyobserver) differences from actual image; 3: Very' good-predicted image clinicallyrepresentative with only minor (only noticeable bytrained clinician) differences from actual image; 4: Excellent-predicted image indistinguishable from actual image.Table III. Accuracy of video imaging predictions for mandibular advancement and genioplasty patients(n 15)ScaleArea evaluated0 Poor1 Fair2 Good3 Very good4 Excellent5 Clinically acceptable(3 and 4 combined)Upper lipLower lipLabiomental foldChinSubmental %50%58%57%30%17%3%20%90%67%50%53%77%the actual image most frequently in the upper liparea; the labiomental fold and submental areasshowed the poorest agreement. For the genioplastygroup, the percentage of acceptable images washigher for the submental area but lower for thelower lip, labiomental fold, and chin; these differences were not statistically significant, but approached significance at the chin (p 0.04). Thepredicted images were perceived as agreeing withthe actual image most frequently in the upper andlower lip regions. The scores given the upper lipwere significantly higher (p 0.01) than the labiomental fold, chin, and submental areas. At the chin,71% of the advancement alone and 53% of thegenioplasty patients had acceptable predictions(Fig. 4).None of the predicted images were viewed byeither clinician as more favorable than the actualimage.DISCUSSIONAs the average discrepancies between the actual soft tissue outline and the predicted line drawing were small, and the predictions can be judgedaccurate enough for display to patients and formost treatment planning purposes. Nevertheless, itmust be kept in mind that a 2 mm or morediscrepancy occurred in more than 20% of thepatients for all the lower lip and several of the chinmeasures, so only in 39 of the 56 cases were thepredictions judged accurate enough in these areasfor detailed treatment planning. This probably reflects the paucity of published data on the responseof the lower lip to orthognathic treatment, especially when face height is changed as the mandibleis advanced. Current prediction algorithms thatrely on the ratios of averages do not reflect thevariability of the responses and the interrelationships of horizontal, vertical, and transverse dimensions. To improve the accuracy of the computergenerated line drawings, better data are needed forthe soft tissue changes that accompany vertical andhorizontal changes in the position of bone andteeth.The predicted line drawing of the soft tissueprofile was used in this study for two reasons: First,the software program did not, in the version used,have the capability to measure directly on the

Sinclair et aLAmerican Journal of Orthodontics and Dentofacial OrthopedicsVolume 107, No, 2183100[ ] Mandibular Advancement OnlygOXroll80U), .060. 40CG)0L.12.20Upper LipLower LipLabiomentalFoldChinSubmentalAreaFig. 4. Percentage of video image predictions judged to be clinically acceptable (levels 3 and 4 fromTables II and III).predicted video image; and second, the assumptionwas that the video image modification was directlybased on the predicted line drawing. However, evenif the actual cephalogram and predicted line drawings were coincident, the video image did notalways exactly reflect the line drawing on which itwas based. The specific landmarks the computerused to generate the video image differed slightly,in this version of the software program, in a fewareas from those used in generating the line drawing (e.g., the most anterior point on the lower lipversus the junction of thevermillion and the rest ofthe lip). Such deviations in computer software willonly compound the prediction error if soft:hardtissue prediction ratios derived from cephalogramsare applied to noncoincident measures. 14 This mayrequire the development of specific video imagingsoft tissue ratios for specific programs (Table IV).As subjectively viewed by the two clinicians, allthe video image predictions were considered acceptable for patient education, even without theuse of any computerized smoothing or blendingfunctions to improve the esthetics of the image.With the addition of this step, which should takeonly 1 to 2 minutes per case, the performance ofthis or any other program is likely to be significantlyimproved (Fig. 5). While these functions are inessence "prettifiers," which do not improve thescientific information content, they are useful inproviding "clean" images for patient education. Itwas also clear to the evaluators that when simultaneously viewing the actual and predicted images onTable W. The ratios developed in this study ofthe soft tissue to hard tissue changes seen inthe video image predictionsNose anteriorNose baseSoft tissue point AUpper lip anterior pointUpper lip stomionLower lip stomionLower lip anterior pointSoft tissue point BSoft tissue 280.260.310.200.100.351.001.00the screen, in all cases the acutal final images wassuperior in esthetics to the prediction. In no casedid the predicted image produce an outcome betterthan the surgeon was able to achieve in real time.This was due to the computer image alwayspresenting with a slightly rasterized or jagged appearance.With this fear allayed, we found considerablygreater interest from the surgeons in using theimaging system as a tool for patient education.Concerns about the image providing an impliedwarranty can be addressed by having phrases suchas Treatment Simulation Only appear on the screenoverlayed on the computer image, or by the use ofa video imaging informed consent form, such asthat recommended by the American Academy ofFacial Plastic and Reconstructive Surgery. 15 As

184Sinclair et aLAmerican Journal of Orthodontics and Dentofacial OrthopedicsFebruary 1995Fig. 5. Video image prediction before and after application of computerized smoothing function.Sarver has suggested, with the majority of patientshaving seen and recognized many other computersimulations in other situations for what they are,just "simulations," the advantages of having a clinically acceptable image for patient education anddiscussion seems to far outweigh this potential risk.As one gains experience with video imaging,there is a learning curve for the operator thatrelates to the accuracy and ease of use of thistechnology. It is clear that taking accurate andreproducible records is a critical first step. Thepresurgical video images in this study were obtained from slides rather than directly from thepatient. The discrepancies between the actual andpredicted records observed in this study likely arelarger than would be found in a prospective patientevaluation with direct imaging, since imaging fromslides allows no correction of background or patient positioning. Video imaging requires excellentlighting and a white background behind the patient; otherwise the software program may experience difficulty in defining the edges of the patient'sprofile against the background. This can lead to a"fuzzy" soft tissue image. It is also vital that thevideo image be captured and the cephalogram betaken with the patient in the same head positionand with the lips in a similar repose position.Ideally, the physical arrangement of the cephalometer and camera should allow for the simultaneouscapturing of the two images with the patient in areproducible position. Differences in head position,particularly rotational, as well as differences in lipposture, were probably responsible for some of theimaging errors seen in this study.Although this study primarily focused on mandibular anteroposterior movements, considerablevertical change occurred in many of the advancements. It appeared that the greater the mandibularadvancement and particularly the greater the vertical change, the poorer the lower lip predictionbecame. In addition, the larger adjustments showedgreater need for smoothing in the submental area.Future video imaging studies must therefore carefully evaluate vertical changes, including those involved with maxillary movements.It should be pointed out that this study wascarried out with the technology available in the firsthalf of 1992 and considerable improvements inmethods have occurred since that time. Also, thestudy represents the results of only one softwareprogram's approach to video imaging, and studiesof other programs should be initiated to compareoutcomes and broaden our knowledge and understanding of video imaging. Future studies shouldalso include psychologic evaluations of patientswho were video imaged as part of their orthognathic treatment so as to understand their responses, as has been done by Kiyak et al.' forseveral groups of orthognathic patients. Improvedsoft tissue ratios specific to imaging need to bedeveloped and comparisons of the same patientsimaged on different software systems need to be

Sinclair et al.American Journal of Orthodontics and Dentofacial OrthopedicsVolume 107, No. 2c a r r i e d o u t so t h a t t h e b e s t a p p r o a c h to i m a g i n gc a n b e identified. C u r r e n t l y v i d e o i m a g i n g is b e i n ga p p l i e d to t h e m a t u r e a d u l t face. C o n s i d e r a b l escientific e v a l u a t i o n o f t h e t e c h n i q u e is r e q u i r e d tod e t e r m i n e w h e t h e r it r e p r e s e n t s a scientific b r e a k t h r o u g h , o r w h e t h e r its p r i n c i p a l role is in p a t i e n te d u c a t i o n . A n y c o n s i d e r a t i o n o f its a p p l i c a t i o n tot h e g r o w i n g face s h o u l d a w a i t r e s o l u t i o n o f t h e s equestions.8.9.10.11.REFERENCES1. Kiyak HA, Bell R. Psychosocial considerations in surgeryand orthodontics. In: Proffit WR, White RP, eds. Surgicalorthodontic treatment. St Louis: Mosby Year-Book, 1991:71-95.2. McNeil RW, Proffit WR, White RP. Cephalometric prediction for orthodontic surgery. Angle Orthod 1972;42:154-64.3. Bhatia SN, Sowray JH. A computer-aided design for orthognathic surgery. Br J Oral Maxillofac Surg 1984;22:237-53.4. Harradine NWT, Birnie DJ. Computerized prediction of theresults of orthognathic surgery. J Maxillofac Surg 1985;13:245-9.5. Walters H, Walters DH. Computerised planning of maxillofacial osteotomies: the program and its clinical application.Br J Oral Maxillofac Surg 1986;24:178-89.6. Lew KK. The reliability of computerized soft tissue prediction following bimaxillary anterior subapical osteotomy, IntJ Adult Orthod Orthognath Surg 1992;7:97-101.7. Laney TJ, Kuhn BS. Computer imaging in orthognathic and12.13.14.15.185facial cosmetic surgery. Oral Maxillofac Clinics North Am1990;2:659-68.Sarver DM, Johnston MW, Matukas VJ. Video imaging forplanning and counseling in orthognathic surge

Peter M. Sinclair, DDS, MSD, a Pauli Kilpelainen, DDS, b Ceib Phillips, PhD, MPH, . 178 Sinclair et al. American Journal of Orthodontics and Dentofacial Orthopedics February 1995 . 9-