ACCURACY OF STO PREDICTION

Introduction:
Orthognathic surgery for the correction of facial deformities and severe malocclusions has
been performed more frequently and involves a much wider range of operative procedures than
in the past. The criteria for a successful surgical outcome is not only the correction of skeletal
and dental abnormalities but also an aesthetic improvement as judged by both patients and
practitioners.
Since Tweed (1954)1 first presented his ‘diagnostic triangle’, many orthodontists includ ing
Steiner, Holdaway and Hilgers have developed the concept of using cephalometric tracings to
establish precise treatment objectives. Holdaway (1983)2 in particular, proposed a method of
overlay prediction tracing for a patient requiring orthodontic treatment. His analysis brought
together factors such as growth increments, stability and soft tissue balance to form a
Visualised Treatment Objective (VTO).
It was Wolford (1985)3 who used the VTO for surgical-orthodontic treatment planning and
coined the term Surgical Treatment Objective (STO).

Uses of an STO: (Taylor 1998)4

 Plan dental movements.
 Assess need for extractions
 Plan mechanics.
 Plan type of surgery and nature of osteotomies.
 A basis for communication
 A basis for informed consenting.
 A basis for splint construction.
 Provides a reasonable prediction of soft tissue changes, that can provide a basis for computer
imaging.
 In recent studies, Kiyaki found that 53% of female patients and 41% of male patients listed
aesthetics as a major factor in their decision to proceed with orthognathic surgery. Other
studies report that 76% to 89% of patients rate aesthetics as a moderate to major factor in their
decision to pursue treatment. Clearly a treatment prediction technique that provides both
accurate diagnostic information required for treatment planning and a realistic simulation of
the aesthetic outcome is needed to maximize the chances of patient satisfaction.

Methods of surgical outcome prediction:

The objective of treatment simulation is to allow the clinician to visualize and manipulate the
skeletal and dental structures, so to compare different treatment alternatives.
There are five general methods of visualising, planning and predicting surgical-orthodontic
treatment outcomes.

1. The first method has been in use for the past 20 years.
 Acetate tracings of skeletal structures are manually repositioned over the origina l
cephalometric tracing to simulate the proposed surgical movements. ii
 The posttreatment soft tissue outcome is established by using acceptable guidelines for the ratio
of soft to hard tissue changes.
 The two major weaknesses of this technique is that:
I. Variables in soft tissue thickness, tonicity, individual responses
II. Differences in the surgeon’s manipulation will introduce uncertainties that make soft tissue
prediction more of an ‘art’ form.
III. The ‘line drawing’ produced by this approach is an inadequate means by which to portray the
proposed result to the patient.

2. Manipulation of patient photographs (cut and past) to illustrate treatment goals.iii. Traditionally,
the lateral cephlogram was traced and superimposed onto a profile picture in a ratio of 1:1; this
has been called a "photometric plan". The photograph, with the hard tissue points marked, was
then cut-up to simulate the pre-surgical orthodontic phase of incisor decompensation. The
necessary surgical movements were then undertaken; followed by the soft tissue response to
the hard tissue movements. The end results sometimes looked a bit like a Picasso picture!
3. Computerised diagnostic and planning software that produced a soft tissue profile ‘line
drawing’ as a result of manipulation of digitised structures of lateral cephalometr ic
radiographs. iv,v Using any of the commercially available programmes, the clinician can
simulate surgical movements on the screen and rapidly compare different treatment options.
Hard copies can then be used as visual aids in treatment planning. This method of prediction
is no more accurate than manual predictions as the computer predictions are based on the same
guidelines and the resultant line drawing is still lacking in providing a lifelike aesthetic
representation.
4. Computerised diagnostic and planning software that integrates video images with the patient’s
lateral cephalograph to aid in planning and predicting surgical orthodontic procedures
(Videocephalometrics). Visualisation of facial changes is enhanced as is patient/clinic ia n
communication; alternative treatment plans can be evaluated with ease, and realistic patient
expectations may be achieved. (Harradine 1985, Sarver 1988, Sinclair 1995).
5. Three-dimensional computer technology for planning and predicting orthognathic surgery.
Moss et al (1988)vi expanded on the early methods of 3-D planning by including laser
scanning to model the soft tissue response to hard tissue movements.
Two significant advantages of video imaging over other prediction techniques are:
  The image facilitates communication between clinician and patient by establishing visua l
treatment goals for orthodontics and surgery. By involving the patient in the decision of
treatment options, acceptance of the treatment outcome should be improved.
 Valuable aid in treatment planing decisions by providing a maniputable image for the
orthodontist and surgeons to decide on the best soft tissue outcome. This technique is also
helpful on deciding the necessity of adjunctive soft tissue procedures.

Radiographic Analysis
In order to use a computer programme to plan orthognathic treatment, the radiograph needs to
be digitised prior to analysis. Two methods are described (Travess and Juggins, 2007):
1. Direct computer digitisation of the radiograph:
• The radiograph is placed onto a digitising light box
• Anatomical points are entered into computer using a cursor or electronic pen
2. Indirect computer digitisation of the radiograph:
• Image is captured (scanned image or true digital image) and stored on the computer.
• Image displayed in orthognathic programme and digitised using a cursor.
Studies have shown that the direct and indirect methods of cephalometric analysis are
comparable (Richardson, 1981; Oliver, 1991; Sarver, 1998).
There are advantages to using the indirect method:
• Digital storage of radiographs allows easy access when required
Use of magnification, alteration of brightness and contrast allow more detailed visualisation of
the image

Orthognathic Prediction Software

There are numerous programmes available for the analyses and prediction of orthognathic
treatment:
• OPAL image version 2.2
• Dolphin imaging 10
• Dentofacial Planner 8.05
• Quick Ceph Image
• Computer assisted simulation system for Orthognathic surgery (CASSOS)
There have been several studies evaluating the accuracy of digitisation and validity of
computerised prediction of surgical outcome.
Power et al. (2005) compared the accuracy of cephalometric digitisation and orthognathic
prediction of Dolphin Imaging 8 with manual tracing (the "gold standard"). Both methods were
reliable at identifying cephalometric points. Of note, manual tracing was more reliable for
SNA, SNB, SNMx and MxMd. In contrast Dolphin imaging 8 was more reliable for UIMx and
LIMd, although systematic error in the software meant that LAFH% was 4% larger than
manual tracing (this has been corrected in Dolphin Imaging 10).
Loh et al. (2001) analysed the accuracy and reliability of Quick Ceph Image software (version
3). There was good correlation between repeated digitisation for all measurements. The only
variables to show statistically significant differences were ANB, FMA, SN-Mx1 and Wit's but
only the Wit's analysis showed clinically relevant differences between the two measurements.
The authors concluded that clinicians should be cautious when using this system; it may not be
possible to achieve the planned surgical result based upon this system's information.
CASSOS prediction of hard tissue profiles was evaluated in a retrospective analysis by Loh
and Yoe (2002). Results showed good correlation between repeated digitisation for all
measurements. The differences that were statistically significant were in angular measureme nts
for SNA, U1-Mx, U1-L1, U1-SN. None of the measurements demonstrated a clinically relevant
difference.
More recently CASSOS was evaluated for its validity in planning surgical correction of Class
III deformities (Jones et al., 2007). Two groups were compared, maxillary advancement and
bimaxillary surgery. For the maxillary advancement group there were statistically significa nt
differences in three horizontal landmarks: superior labial sulcus, labrale superius and the
labiomental fold. In the bimaxillary group only the landmark labrale superius (in the vertical
direction) showed a statistically significant difference. The authors commented that CASSOS
produced useful predictions; however there was wide interindividual variation, mainly for the
lips.
Smith et al. (2004) investigated the ability of prediction imaging software to simulate the actual
outcome of orthognathic surgery. Five programmes were compared - Dentofacial Planner Plus,
Dolphin imaging, Orthoplan, Quick Ceph Image and Vistadent. Ten difficult vertical
discrepancy cases were chosen and "retreated" with the programmes using the actual surgica l
changes. Dentofacial Planner Plus was judged the best default simulation. The authors also
noted that programme choice is not only related to simulation ability but also performance,
cost, ease of use, compatibility, image and and for some practitioners the inclusion of a practice
management tool.
OPAL software (Orthodontic planning and analysis) was developed by Nigel Harradine and
David Birnie and George Chauvet in 1983. It has undergone numerous revisions since its initia l
presentation. Cousley et al. (2003) investigated the accuracy of OPAL in the calculation of the
total treatment hard tissue and dental changes. Prediction of the majority of the variables was
acceptable, however there was large interindividual variation for most measurements ;
prediction of Wits, MxP/MdP, LAFH and LPFH were prone to systematic error. There was
also a tendency towards over-prediction of the surgically- induced backward mandibula r
rotation. A follow-on study was carried out which assessed the accuracy of OPAL preoperative
prediction in relation to immediate and long term changes in mandibular advancement
(Cousley and Grant, 2004). Overall the wafer had a limited anterior displacement (0.1mm) but
2.1mm of bite-opening measured at the incisor level. There was little difference in actual and
predicted values for LAFH%, SNA, ANB, OJ and OB. The most pronounced inaccuracies were
in L1/MdP. The vertical skeletal measurements (MxP/MdP, LAFH and LPFH) were
significantly under-estimated in both the immediate and long term predictions. In essence the
programme underestimated the amount of backward rotation of the mandible as it was
advanced.
However, it is important to ask ourselves if the use of 2D prediction software is more useful to
clinicians than to patients and whether patients ever look at themselves in profile?
Phillips et al. (2001) investigated the effects of computerized treatment simulation on patient
expectations of orthognathic treatment. One hundred and forty-six patients requiring combined
orthodontic and orthognathic treatment were randomly allocated to two groups: presurgica l
consultation with, and without, computerised treatment simulation software. Viewing a
prediction did not have a significant effect on the anticipation of social relations and general
health in the first month after surgery. Psychologically distressed patients, whether or not they
saw a simulation, expected significantly more problems in social interaction and general health
in the first month after surgery. Treatment simulation did affect patients' overall expectations
of problems in the first month after surgery and their concerns about symptom recovery

VIDEO IMAGINGvii
 Does the prediction image create an unrealistic expectation of the final result?

Does sharing the image with the patient represent an implicit warranty as to the treatment
outcome?

Phillips et al (1995)10 found that the presentation of video images appears to be a valuab le
adjunct for conveying treatment options to patients, but warned that caution may be needed to
avoid elevated or unrealistic treatment expectations. Video imaging was found to heighte n
patients’ expectations of improvement in self-image following treatment.
 Kiyak (1991)5 showed that fewer than 45% of non-imaged patients were satisfied with their
aesthetic result.
 However, Sarver et al (1988)9 found that 89% of the patients believed that the image
predictions were realistic and that desired results were achieved.
 Furthermore, 83% believed that the imaging process helped them in deciding whether to have
surgery or not,
 72% believed the process allowed them to take part in specific treatment decisions.
 Fear that the patients expectations may be too high do not appear to be supported.

How accurate is the prediction?

There are few studies investigating the validity of methods predicting the soft tissue outcomes
after orthognathic surgery.
Pospisil (1987)viii evaluated manual acetate tracings and found 60% inaccuracy when compared
to 6-month postoperative radiographs. He stated that soft tissue profiles in 83% of
2-jaw and 40% of single jaw cases were inaccurately predicted. The magnitude and direction
of discrepancy was not reported.

Hing (1989)ix and Sinclair (1995)14 used records of patients who had mandibular advancement
surgery to investigate the accuracy of computerised soft tissue line drawings. Sinclair et al
(1995) also compared the accuracy of line drawings of patients who had mandibula r
advancement with those who had both mandibular advancement and advancement genioplas ty.
Sample of 56 patients from the office of one of the authors (D. Sarver), who had completed
treatment involving orthodontics and orthognathic surgery to advance the mandible a minimum
of 5mm. 41 had mandibular advancement only and 15 had an additional advancement
 genioplasty. All patients were over 18 years old, white and selected on the basis of the
availability of presurgical and posttreatment lateral cephalograms and lateral profile
photographs. All records were taken with teeth together in centric occlusion and lips in repose.
By superimposing the computerized hard tissue prediction (using Prediction Planner/Portra it
imaging system) with the actual hard tissue result, it was possible to compare and analyze the
accuracy of the soft tissue outline.
To assess the accuracy of the video image predictions, the actual initial, the actual final and the
predicted final images were displayed simultaneously on the monitor. These three images were
evaluated and scored independently by an oral surgeon and an orthodontist, for the similar ity
between the actual final and the predicted final images.

Actual versus predicted line drawings

The mean differences on the posttreatment soft tissue profile was small and statistica lly
insignificant for measures other than the lower lip. The computer predicted lip was
significantly more retrusive when compared with the E-line and a vertical through subnasale
(SNV-line). The lower lip was also predicted to be thinner than it actually was.

For 11 of the 18 measurements taken, a 2mm of greater discrepancy was found in at least 20%
of the patients. Differences at the chin point were higher than would be expected from mean
changes alone. For the majority of patients the 2mm discrepancy was an underprediction.

Actual versus predicted video images

1. Mandibular advancement only: predicted and actual images agreed most often in the upper lip
area; poorest agreement in the labiomental fold and submental areas.

2. Genioplasty group: agreement most frequent in upper and lower lip areas.
The percentage of acceptable images was higher in submental areas but lower for
labiomental fold and chin.
 71% of mandibular group and 53% of genioplasty group had acceptable predictions at the chin.

Results:
 more than 20% of patients had 2mm discrepancy at lower lip and chin. Current prediction
algorithms based of ratios of averages do not reflect the variability of responses and the
 interrelationships of horizontal, vertical and transverse dimensions. To improve accuracy of
computer line drawings, better data is needed for soft tissue changes that accompany vertical
and horizontal skeletal and dental changes.
 all video image predictions were considered acceptable for patient education.
 in all cases the actual final images were superior in aesthetics to the prediction images.
 the greater the mandibular advancement and the greater the vertical change, the poorer the
lower lip prediction.

Hing used the Quick-Ceph diagnostic software programme and he found that the largest
amount of discrepancy between the computer predicted profile outline and the posttreament
radiographic tracing was in the horizontal position of the lower lip and the vertical position of
soft tissue Pogonion.
 predicted position of lower lip was more anterior
 predicted position of soft tissue pogonion was more superior

Konstiantos et al (1994)x investigated the accuracy of computer predictions of patients who

had LeFort 1 osteotomy, using the Dentofacial Planner imaging system.
 nasal tip (pronasale) and nasal base (subnasale) were more posterior on the prediction
 position of lower lip was more retrusive on the prediction

Upton et al (1997) evaluated the accuracy of soft tissue profile ‘line drawings’ predicted by
Quick-Ceph in combined maxillary and mandibular orthognathic surgery procedures. In this
study preoperative and posttreament lateral cephalographs of 40 white patients (10 males, 30
females) who had undergone LF1 and BSSO advancement with or without genioplasty were
used. 45 hard and soft tissue landmarks were digitised for each readiograph. Results indicated
variability among several of the landmark positions when comparing prediction tracings with
posttreament radiographs, with more variability in vertical measurements than in horizontal or
angular measurements. This current study revealed more measurements that were statistica lly
significantly different from posttreatment tracings than did previous validity studies. One
explanation may be that in this study patients had 2-jaw surgery whereas other study samples
had only single jaw procedures. Other reasons include the different soft and hard tissue ratios
used in different software packages and different statistical methods employed. The Quick-
 Ceph programme uses soft and hard tissue ratios published by Wolford (1985) 3 and Epker and
Fish (1986)xi.
 amount and direction of soft tissue changes differed between predicted and actual tracings
 most differences were in the horizontal and vertical positions of the lower lip
 lower lip was predicted to be more inferior, shorter and more protrusive
 upper lip was predicted to be shorter
 soft tissue pogonion was predicted to be more inferior
Gerbo (1997)xii in a retrospective study of the accuracy of a prediction algorithm from Quick-
Ceph, digitised lateral cephalographs of 35 adult patients. Results showed good correlatio n
between repeated digitisation of all variables except soft tissue B point and the E-plane.
Comparison of predicted and actual changes showed that all differences were less than 1.8mm
or 3.1 degrees. 10 of the 16 measurments did not differ significantly and were judged to be
within clinically acceptable limits.

Can the surgeon actually produce the suggested outcome?

Donatsky et al (1997)xiii applied a computerised cephalometric, orthognathic surgical

programme (TIOPS) in simulation, treatment planning and postsurgical records, to assess
precision and stability of bimaxillary surgery. This prospective study included 40 consecutive
patients requiring maxillary superior repositioning combined with mandibular advancement or
setback. All were managed with rigid wire fixation. Planned, 5-week postsurgical and 1-year
postsurgical cephalometric positions were compared.
In mandibular advancement group:
 anterior maxilla was placed too far superiorly, with an inaccuracy of 0.4mm. Posterior maxilla
and anterior mandible were placed in the planned positions.
 Lower posteior part of mandibular ramus was placed too far anteriorly with inaccuracy of
2.0mm. However condyles were in correct positions.

In mandibular setback group:

 anterior maxilla was too far superiorly and posteriorly with a vertical and horizontal inaccurac y
of 1.0mm and 0.7mm respectively.
 Lower posteior part of mandibular ramus was placed too posteriorly with inaccuracy of 0.9mm.
Again, condyles were in correct positions.
 Stability:
1-year data showed maxilla had moved 0.3mm posteriorly in the advancement group and
0.8mm superiorly in the setback group. No significant positional changes were observed in the
mandibular ramus.
They concluded that the TIOPS progamme is useful in orthognathic surgical simulatio n,
planning and prediction, and also in evaluation of surgical precision and stability. The
simulated treatment plan can be transferred to model surgery and then on to surgica l
procedures. The results suggest that this technique yields acceptable postoperative precision
and stability.

In a review of the current capabilities and limitations of video imaging, Grubb et al (1996)11
discusses the factors affecting the accuracy of video imaging. He considers the accuracy of the
predictions is dependent on three components:

 accuracy of the computerized cephalometric VTO. Researchers have shown a reasonable

accuracy in the A/P plane when compared to manual tracings, and slightly poorer but still
acceptable accuracy in the vertical plane. All the software tested had problems predicting the
position of the lips, especially the morphology of the lower lip.
 ability of the program to fit the facial image onto the corresponding soft tissue cephalometr ic
outline. All programs tested differed; an optimal system is yet to be developed.
 image morphing. Sinclair (1995) reports that 70% of video images produced are accurate
enough for clinical use without any additional operator influence in blending or smoothing the
profiles. Less than 50% of images predicting the position and contour of the lower lip showed
acceptable accuracy.

Soft Tissue Profile Changes Associated with Surgical Movement

The recognition of the importance of aesthetic factors in orthognathic treatment is a very
important part of the planning process. Knowledge of the relationship between hard tissue
changes and the effect this has on the overlying soft tissues is essential when planning and
predicting facial changes.
Moss et al. (1988) noted that the various type of orthognathic procedures and the anatomica l
morphology of the patient must be considered when predicting the outcome of facial surgery.
Mandibular setback procedures
The first studies on the effects of surgery on the soft tissues were associated with mandibula r
reduction procedures (Knowles 1965). It was found that for each 1mm of posterior movement
of the mandible, soft tissue pogonion moved posteriorly between 0.9-1mm while the soft tissue
lip moved back 0.6-0.75mm (Shiu-Shiung et al. 1998).
Mandibular advancement:
Veltkamp et al (2002) confirmed that the direction of surgical movement and preoperative soft
tissue thickness have a definitive effect on the post-operative lower lip position. As the
mandible advances the lower lip contour straightens and the vermillion thins. The authors
confirmed that the effect of maxillary surgery in conjunction with anterior mandibula r
advancement on the soft tissue contour of the lower lip is similar to an isolated single jaw
procedure.
Mobarak et al. (2001) investigated changes in soft tissue profiles following mandibula r
advancement surgery. In a sample of 61 patients with retrognathic mandibles the authors
confirmed that the soft tissue chin and labio-mental fold followed their underlying skeletal
structures in a 1:1 ratio. They did however suggest that more realistic long term projection may
be achieved if ratios incorporating mean relapse values were used rather than relying on a 1:1
relationship.
Mandibular advancement with genioplasty:
Ewing and Ross (1992) carried out a study on 31 patients investigating the soft tissue response
to mandibular advancement and genioplasty. The results showed a consistent 1:1 ratio of soft
tissue to hard tissue movement at pogonion and point B; with accurate predictions in both
antero-posterior directions. When a genioplasty was added to the advancement, however, the
results became much less consistent. The mean ratio was 0.9:1 but had a variation of +/- 2.6mm
which was not sufficiently accurate for predictive purposes. After genioplasty the soft tissue
pogonion moved inferiorly relative to the underlying hard tissue pogonion. The behaviour of
the lip was also variable between the two groups. Advancement thinned the lip by an average
of 1.7mm. Changes in the vertical dimension were also more variable with a range of 4mm
recorded depending on the operator. This variation means that surgeons must assess the soft
tissue reaction pertaining to their technique.
Maxillary procedures at Le Fort I level:
There have been many studies attempting to assess the soft tissue changes that occur with Le
Fort I surgical procedures. Initial ratios proposed by Lines and Stenhauser (1974) stated that
there was a 2:3 soft tissue: hard tissue ratio in the maxilla although the number of patients
included in this study was very small.
Costa et al. (1986) investigated 25 cases of Le Fort I maxillary advancement and naso-labia l
reconstruction and found a lip to osseous ratio of 0.9:1. This is a higher ratio than in other
studies but may be due to the naso-labial reconstruction process.
Stella et al. (1989) followed 21 maxillary advancement patients for at least 6 months post-
operatively and found no reliable correlations between bony advancement and soft tissue
position. However they did find that tissue changes varied with different lip thicknesses.
Hack et al. (1992) collected cephalometric data from 25 patients who underwent either a Le
Fort l or a bimaxillary procedure. They aimed to establish the long term stability and prediction
of soft tissue changes after Le Fort I surgery and found that the short term soft: hard tissue
correlations were in the range suggested by previous authors.
They concluded that soft tissue settling and maturation may take several years to complete.
Bimaxillary Procedures
Jensen at al. (1992) investigated the response of simultaneous maxillary impaction and
mandibular advancement. They suggested that the soft tissue responses seen were similar to
single jaw procedures, with the exception of changes to the naso-labial angle and the labio-
mental fold. With maxillary advancement and impaction, the upper lip advanced 90% of the
underlying hard tissue change and moved superiorly by 20% of the hard tissue movement. The
naso-labial angle changed about 60% of the rotation of the maxilla.
Shiu-Shiung et al. (1998) aimed to clarify the soft tissue changes that occur with maxilla r y
advancement and mandibular set back when correcting Class III malocclusions, using the V-Y
closure technique and alar-base cinch suture. In a sample of 17 patients undergoing bimaxilla r y
osteotomy, superimposition cephalometric analysis was carried out post-operatively. They
found similar results to previous studies in that the mandibular hard tissue to soft tissue ratio
was 1:1 at pogonion and point B. The maxillary ratios correlated less strongly with maxilla r y
advancement. The ratio of the superior labial sulcus and A point was less than that of the lower
lip and chin, ranging from 0.4:1 to 0.82:1.
This wide variation may be due to the modification of various cephalometric landmarks such
as ANS.
Vertical movements of the mandible showed a strong correlation in the lower lip and chin but
vertical movement of the maxilla showed a weak correlation at the level of the nasal base and
upper lip.
 Advancement genioplasty
Shaughnessy et al. (2006) aimed to assess the skeletal stability of advancement genioplasty 3
years after surgery and to evaluate the predictability of soft tissue changes in 21 patients
underwent genioplasty advancement only. At 3 years the soft tissue of the chin was found to
follow the bony movement in a ratio of 0.9:1 but great individual variability was observed.

CONCLUSION:
“ In any creative endeavour, orthodontics included, one must have an idea, a mental image of
his objective.” King12

The integration of video imaging into the counseling of patients on aesthetics consideratio ns
of treatment offer several advantages:
 a higher level of communication
 more precision in this communication

 improved visualisation of individual treatment plans, resulting in greater precision in planning

a desired outcome
 a template is provided for decision-making among patient, orthodontist and oral surgeon, with
greater participation by the patient
 Quantitates surgical movements
 allows facial planing and provided quantitative feedback as to what is required to attain a
particular treatment plan.

It is clear that surgical treament prediction methods are a valuable tool in planning and
simulating treatment objectives. From the literature it appears that manual acetate tracings
alone were more inaccurate in predicting treatment outcomes than the more advanced
technology of video imaging. Different degrees of inaccuracy are reported in different studies
assessing the validity of videocephalometrics, mainly due to different soft /hard tissue ratios
used in various software. With continued technological advancements and the development of
more accurate soft /hard tissue ratios, we can look forward to more accurate prediction methods
that facilitate greater success in orthognathic surgery and greater patient satisfaction.

_____________________________________
REFERENCES:
1 Tweed, C. The Frankfort-mandibular incisor angle (FMIA) in orthodontic
diagnosis. AJO 1954; 24:121-169
2 Holdaway, R. A soft tissue cephalometric analysis and its use in orthodontic
treatment. AJO 1983; 84:1-28
3 Wolford, L.et al STO prediction tracing. 1985 Mosby, St.Louis
4 Taylor, P. In ‘orthodontics and dentofacial orthopaedics’ Ch.
i Kiyak HA, Bell R. Psychosocial considerations in surgery and orthodontics.
Proffit W, White R. Surgical orthodontic treatment.1991 p71-
95
ii McNeil, Proffit, White. Cephalometric prediction for orthodontic surgery.
Angle 1972; 42: 154-64

iii Kinnebrew M. et al Projecting the soft tissue outcome of the surgical and
orthodontic manipulation of the maxillofacial skeleton.
AJO 1983;84: 508-19
iv Bhatia S, Sowray J. A computer-aided design for orthognathic surgery.
Br J Oral Maxfac Surg 1984; 22: 237-53

v Harradine N, Birnie D. Computerized prediction of the results of orthognathic surgery.

J Maxfac Surg. 1985; 13: 245-9

vi Moss et al A computer system for the interactive planning and prediction

of maxillofacial surgery.
AJO 1988;84: 469-75
vii Sarver D et al Video imaging for planning and counseling in orthognathic
surgery.
J Oral Maxfac Surg 1988; 46: 939-45

10 Phillips, C et al The influence of video imaging on patients’ perceptions and

expectations. Angle 1995; 65(4): 263-270

viii Pospisil O Reliability and feasibility of prediction tracing in orthognathic

surgery.
J. Cranio. Max Fac Surg 15:79-83
ix Hing N The accuracy of computer generated prediction tracings.
Int J Oral Maxfac Surg 1989;18: 148-51
x Konstiantos et al The validity of prediction of soft tissue profile changes after
LF1 osteotomy using Dentofacial planner.
AJO 1994; 105:241-9
xi Epker N and Fish L Systematic evaluation of the patient with a dentofacial
deformity. 1986 Mosby p17-21
xii Gerbo et al A comparison of a computer-based orthognathic surgery
prediction systmen to postsurgical results.
Int J Adult Ortho & Orthog Surg 1997; 12(1):55-63

Donatsky et al
xiii Computerised cephalometric evaluation of orthognathic
surgical
precision and stability in relation to bimaxillary surgery.
J of Oral & Maxfac Surg 1997; 55(10): 1071-9
11 Grubb, J et al Clinical and scientific applications/advances in video imaging.
Angle 1996; 66(6): 407-416
12 King, E. Relapse of orthodontic treatment.
Angle 1974; 44: 300-15