The reliability of AutoCAD program in cephalometric analysis in comparison with pre¬programmed cephalometric analysis software

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Conservative Dentistry
The reliability of AutoCAD program in cephalometric analysis in comparison with pre-
programmed cephalometric analysis software
Mohammed Nahidh, B.D.S., M.Sc
Lecturer, Department of Orthodontics, College of Dentistry, University of Baghdad
Ahmed F. Al-Jarad, B.D.S., M.Sc.
Assistant Lecturer, Department of Orthodontics, College of Dentistry, University of Baghdad
Zana H. Aziz, B.D.S., M.Sc.
Orthodontist. Ministry of Health. Sulimani Governorate
INTRODUCTION
Since Broadbent (1) and Hofrath (2) introduced
the cephalometer in 1931, cephalometric analysis has
contributed to the analysis of malocclusion and it has
become a standardized diagnostic method in ortho-
dontic practice and research (2–4).
Twoapproachesmaybe usedtoperformacephalo-
metric analysis: a manual approach and a computer-
aided approach. The manual approach is the oldest
and most widely used. It consists of placing a sheet
of acetate over the cephalometric radiograph, tracing
salient features, identifying landmarks, and measur-
ing distances and angles between landmark locations.
Theotherapproachiscomputer-aided.Computerized
cephalometric analysis uses manual identication
of landmarks, based either on an overlay tracing of
the radiograph to identify anatomical or constructed
points followed by the transfer of the tracing to a digi-
tizer linked to a computer, or a direct digitization of
the lateral skull radiograph using a digitizer linked to
a computer, and then locating landmarks on the moni-
tor (5–7). Afterwards, the computer software completes
the cephalometric analysis by automatically measur-
ing distances and angles.
 Themajor sources of error incephalometric
analysis include radiographic lm magnication,
tracing, measuring, recording, and landmark identi-
cation.Previousstudiesrevealedthatinconsistency
inlandmarkidentication is an important sourceof
error in conventional cephalometry (8-10).
 Thiserrorisspecictoeachlandmarkandaf-
fected by experience and training of the observers (11).
Rapid advances in computer science have led
to its wide application in cephalometry. Computer-
aided cephalometric analysis is faster in data acquisi-
tion and analysis than conventional methods. Many
cephalometric programs have been developed to
perform computer-aided cephalometric analysis by
digitizing the landmarks. However, digitizing may
introduce errors such as head lm movement and
impropersequencingofdigitizedpoints.Totakead-
vantageofimageprocessingandcomputer-basedl-
ing systems that can integrate patients’ records and
images,theoriginalcephalometricradiographiclms
may be transformed into a digital format by a scan-
ner or video camera. A radiographic system for taking
direct-digital lateral cephalograms at reduced radia-
tion dose is presently available (12,13).
Consequently, many commercially available
or customized programs have been developed to con-
duct cephalometric analyses directly on the screen-
displayed digital image (14–15). Such applications could
substantially reduce the potential errors in the use
of digitizing pads and totally eliminate the need of
hardcopies of digitally born images for conventional
cephalometric analysis (15). Digital cephalometry also
has the benets of image storage, transmission and
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ABSTRACT
Background: This study aimed to evaluate the reliability of AutoCAD program in cephalometric analysis in comparison with View-
box 3.1.1 cephalometric computer soware.
Materials and method: The sample consisted of 30 digital true lateral cephalometric radiographs of some under- and postgradu-
ate students in the College of Denstry/ University of Baghdad. Seventeen parameters (11 angular and 6 linear) were measured
using the Viewbox 3.1.1 cephalometric computer soware and re-measured using AutoCAD program. Descripve stascs were
performed for each parameter and paired samples t-test was obtained to evaluate the dierence between both of the methods.
Results: The results revealed the presence of non-signicant dierence between both sowares.
Conclusions: Cephalometric analysis with AutoCAD program was comparable with Viewbox 3.1.1 soware and both of them de-
pend on the landmarks idencaon by the observer. AutoCAD soware is available in Iraq unlike the other sowares and it can
be used in clinical diagnosis also suited for research projects.
Key words: AutoCAD, computerized cephalometric analysis.

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processing (8).
Greateffortshavebeenmadetodevelopsystemsfor
automaticcomputerizedidenticationofcephalomet-
ric landmarks (4,17). However, automated systems are
atpresentunabletocompetewithmanualidentica-
tionintermsofaccuracyoflandmarkposition.The
landmarkslyingonpoorlydenedstructuresaredif-
culttoautomaticallyidentifyduetopoorsignal-to-
noise ratio (8). Earlier studies revealed that comput-
er-aided cephalometric analysis does not introduce
more measurement error than hand tracing, as long
aslandmarksareidentiedmanually(18,19).Therefore,
manually identifying landmarks on screen-displayed
digital images for cephalometric analysis may still be
the better strategy.
In Iraq, before 2006, the manual tracing was the dom-
inate method for cephalometric analysis, but after
transporting to the digital cephalometric X-ray, the
need for a software for cephalometric analysis begins.
Al-Nasseri (20) compared the accuracy of the comput-
erized procedure from digitizing the radiograph to
thenalcephalometricanalysisontwenty-sixlateral
cephalograms using Viewbox 3.0.1 cephalometric
computer software. His results showed that comput-
erized angular measurements were more comparable
to the manual method than with linear measurements,
with most of the differences being of low clinical im-
portance.Ontheotherhand,UthmanandAl-Sahaf(21)
measuredtheeffectoflmdigitizationonreliability
and validity of some angular and linear cephalomet-
ric measurements. They used the Dimaxis pro/clas-
sic imaging software (version 3.2.1) for landmarks
identicationandvariablecalculationsandfoundthat
the angular and linear measurements in digital images
were comparable with that of original radiograph and
areclinicallyacceptable.Thisworkwiththissoftware
is not easy, so the need for simple and full option soft-
ware has been aroused.
Mohammed (22) evaluated the reliability of landmarks
identicationandtheireffecton theaccuracyofthe
linear and angular measurements among the con-
ventional, hardcopy and direct digital cephalographs
of 110 Iraqi adults. Lateral conventional and digital
cephalometric radiographs were taken for each sub-
ject, a hardcopy image from the digital cephalometric
radiograph have been printed. Twenty one cephalo-
metricmeasurements(12angularand9linearmeas-
urements) were determined. Cephalometric analyses
were made by traditional (manual), direct digital
analysisbythePlanmecaSoftwareProgram(Dimax)
and direct manual analysis on the hardcopy image.
Theresultsshowedthatmostofcephalometricland-
markshavebeenidentied with moreprecisionand
reliability within the digital techniques rather than
with conventional and hardcopy techniques. With the
hardcopy analysis technique, all the linear measure-
ments either skeletal or dental showed a high sig-
nicant variation, so it cannot be used to make the
so good diagnosis or the evaluation of the treatment
plan. On the other hand, there was no statistical sig-
nicance difference between the conventional and
digital methods and both techniques could be used
as clinical tool in diagnosis and treatment planning
evaluation.
NowadaysinIraq,AutoCAD(AutoComputerAided
Design) program is the best solution. With this soft-
ware,bothdigital andconventionalX-rays,that can
be scanned and entered to this program, can be ana-
lyzed. It has the property of measuring the angular,
linear parameters and surface area. With it, the image
isimported,themagnicationiscorrectedandpoints
and planes can be obtained easily with the property
of enlarging the image, snapping the points, determi-
nation the mid between two points, drawing the per-
pendiculars, and measuring the variables with high
precision.
Since 2005, AutoCAD program used in cephalomet-
ric analysis and no one test its reliability, so the aim
of the present study is to evaluate the reliability of
AutoCAD program in cephalometric analysis in com-
parison with Viewbox 3.1.1 cephalometric computer
software.
MATERIALS AND METHOD
Sample
Thesampleconsistedof30digitaltruelateralcepha-
lometric radiographs of some under- and postgradu-
atestudentsintheCollegeofDentistry/Universityof
Baghdad.
Equipment
a)Pentium IV portable computer.
b)Analyzing softwares (AutoCAD 2007 by Au-
todesk, Inc., and Viewbox 3.1.1 by Dhal Orthodontic
Software).
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Method
Cephalometric Analysis
Every digital true lateral cephalometric radiograph
was analyzed by Viewbox 3.0.1 cephalometric com-
puter software one time then by AutoCAD program
2007 on the second time to obtain the angular and lin-
ear measurements. After importing the picture to both
oftheseprograms,themagnicationwas corrected,
the points were localized, the planes were determined,
and the angles and distances were measured by the
AutoCAD program while in Viewbox 3.0.1 software
the planes and measurements were obtained directly
as the program designed.
Cephalometric Landmarks, Planes, and Measure-
ments
I. Cephalometric Landmarks
1. PointS(Sella):Themidpointofthehypophysial
fossa (23).
2. PointN(Nasion):Themostanteriorpointonthe
nasofrontal suture in the median plane (23).
3. PointAr(Articulare):Thepointofintersectionof
the external dorsal contour of the mandibular con-
dyle and the temporal bone (24).
4. PointA(Subspinale):The deepest midline point
on the premaxilla between the Anterior Nasal
Spine and Prosthion (25).
5. Point B (Supramentale): The deepest midline
point on the mandible between Infradentale and
Pogonion (25).
6. PointPog(Pogonion):Itisthemostanteriorpoint
on the mandible in the midline(25).
7. PointANS(AnteriorNasalSpine):Itisthetipof
the bony anterior nasal spine in the median plane
(23).
8. PointPNS(PosteriorNasalSpine):Thisisacon-
structed radiological point, the intersection of a
continuation of the anterior wall of the pterygo-
palatinefossaandtheoorofthenose.Itmarks
the dorsal limit of the maxilla (23).
9. PointMe(Menton):Thelowestpointonthesym-
physeal shadow of the mandible seen on a lateral
cephalograms (26).
10. Point Go (Gonion): A point on the curvature of
the angle of the mandible located by bisecting the
angle formed by the lines tangent to the posterior
ramus and inferior border of the mandible (26).
11. PointIi(Incisorinferius):Thetipofthecrownof
the most anterior mandibular central incisor (23).
12. PointIs(Incisorsuperius):The tip of the crown
of the most anterior maxillary central incisor (23).
13. PointAp1(Apicale1):Rootapexofthemostan-
terior maxillary central incisor (23).
14.PointAp1(Apicale1):Rootapexofthemostan-
terior mandibular central incisor (23).
II. Cephalometric planes
1. Sella-Nasion(SN)plane: Formedbyaline join-
ing Sella turcica and Nasion (23).
2. S-Ar plane: Formed by a line joining Sella turcica
and Articulare (23).
3. Ar-Goplane:AlinejoiningArticularetoGonion
(23).
4. N-Pog plane: Formed by a line joining Nasion
and point Pogonion (25).
5. N- A line: Formed by a line joining Nasion and
point A (25).
6. N- B line: Formed by a line joining Nasion and
point B (25).
7. Palatal plane: Formed by a line joining ANS and
PNS (23).
8. Mandibularplane(MP):Formedbyalinejoining
GonionandMenton(23).
9. Longaxisof theupperincisor(U1):Alinecon-
necting Is and Ap 1 (23).
10. Longaxisofthelowerincisor(L1):Alinecon-
necting Ii and Ap 1(23).
11. Mandibular incisor- Mandibular plane: A line
connecting the long axis of the lower incisor to
the mandibular plane (23).
12. Maxillary incisor- Palatal plane: A line connect-
ing the long axis of the upper incisor to the palatal
plane (23).
Cephalometric measurements
A. Angular measurements
1. SNA angle: The angle between lines S-N and
N-A. It represents the angular anteroposterior po-
sition of the maxilla to the cranial base (27,28).
2. SNBangle:TheanglebetweenlinesS-NandN-B.
It represents the angular anteroposterior position
of the mandible to the cranial base (27,28).
3. ANB angle: The angle between lines NA and
N-B. It is the most commonly used measurement
for appraising anteroposterior disharmony of the
jaws (27,28).
4. Gonialangle(Ar-Go-Me):Theanglebetweenthe
posterior border of the ramus and the mandibular
plane(23).
5. Saddle angle (N-S-Ar): The angle between the
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anterior and the posterior cranial base. This an-
gle formed at the point of intersection of the S-N
plane and the S-Ar plane (23).
6. Articular angle (S-Ar-Go): The angle between
S-ArandAr-Goplanes(23).
7. S-N-Pog angle: The angle between S-N and N-
Pog planes (23).
8. SN-PPangle:TheanglebetweenS-Nandpalatal
planes (23).
9. Maxillaryincisor–Palatal plane angle(U1-PP):
Theanglebetweenlongaxisofupperincisorand
palatal plane, posteriorly (27,28).
10. Mandibularincisor–Mandibularplaneangle(L1-
MP):Thatangle formed by the longaxis of the
most labial mandibular incisor to the mandibular
plane, posteriorly (24).
11. Inter-incisalangle(U1-L1):Theangleformedby
the intersection of the lines representing the long
axes of the most labial maxillary and mandibular
incisors, posteriorly (27,28).
B. Linear Measurements
1. S-N: A distance from Sella to Nasion (23).
2. S-Ar: A distance from Sella to Articulare (23).
3. Mandibular body length: It represents the distance
fromGoniontoMenton(23).
4. Ramuslength:ThedistancebetweenAr and Go
(23).
5. Totalanteriorfacialheight(TAFH):It’smeasured
from N to Me (29).
6. Posteriorfacialheight(PFH):It’smeasuredfrom
StoGo(29).
Statistical Analyses
All the data of the sample were subjected to computer-
izedstatisticalanalysisusingSPSSversion15(2006)
computerprogram.Thestatisticalanalysisincluded:
1. Descriptive Statistics
a) Means.
b) Standarddeviations(SD).
c) Statistical tables.
2. Inferential Statistics
a) Paired- samples t-test for the comparison be-
tween both methods.
In the statistical evaluation, the following levels of
signicanceareused:
Non-signicant NS P>0.05
Signicant  * 0.05≥P>0.01
Highlysignicant ** 0.01≥P>0.001
Veryhighlysignicant*** P≤0.001
RESULTS AND DISCUSSION
Different studies had been made to compare between
the manual and computerized cephalometric analy-
sis revealed non-signicant difference between the
methods (6,13).
Baskin and Cisneros (14)conducted a study to deter-
mine the reliability and reproducibility of measure-
ments obtained from two popular programs, Dentofa-
cialPlannerandQuickCeph,ascomparedtomanual
tracings using the measurements of Steiner’s analysis.
TheyfoundthatbothDentofacialPlannerandQuick
Ceph can produce dependable results.
Theresultofthepresentstudyrevealedthatthemean
values of the measured variables by both softwares
wereveryclosewithanon-signicantdifferencebe-
tweenbothmethods(Table1).
For both methods, the cephalometric analysis depend-
edmainlyonlandmarksidenticationbytheobserver
rather than the method of calculating and measuring
of the linear or angular variables.
Althoughtheresultsshowedanon-signicantdiffer-
ence between both softwares; the differences between
them obviously seen in their design. Viewbox was
designed as a cephalometric analysis program devel-
oped by an orthodontist. Initially it was written for
personal computers in the DOS environment and later
it was ported to Windows 3.1. Version 3.1.1 incor-
porates the latest in cephalometric analysis software,
including advanced image processing algorithms,
Procrustes superimposition and Principal Component
Analysis, while AutoCAD program in fact designed
for solving engineering purposes rather than ortho-
dontic analysis. One of the most features in the Au-
toCAD program is that the observer has a full con-
trol in locating points that are between two shadows,
likeGonionunlikepreprogrammedidenticationby
Viewbox 3.1.1 cephalometric computer software.
CONCLUSIONS
AutoCAD program, like Viewbox, is not restricted to
cephalometric analyses, however, this program can
perform measurements on any diagnostic record that
can be scanned with a scanner or photographed with
a video or digital camera. Such records might include
frontal, submentovertex and panoramic radiographs,
orthodontic models, facial and prole photographs,
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hand-wristradiographs,animalradiographs,etc.The
resultsof the present study revealednon-signicant
difference between both methods. Therefore,Auto-
CAD program can be used in clinical diagnosis also
suited for research projects.
Linear
Measurements
(mm)
Variables Descriptive statistics Method difference
d.f.=29
Viewbox AutoCAD
Mean S.D. Mean S.D. Mean
difference
t-test p-value
SNA 82.67 3.25 82.83 3.17 0.17 1.37 0.19(NS)
SNB 79.44 3.15 79.50 2.98 0.06 0.44 0.67(NS)
ANB 3.33 1.33 3.28 1.41 -0.06 -0.44 0.67(NS)
GA 126.22 3.14 126.22 3.32 0 0 1(NS)
N-S-Ar 122.06 5.18 122.56 5.29 0.50 1.84 0.08(NS)
S-Ar-Go 144.50 5.89 143.94 5.92 -0.56 -1.82 0.09(NS)
SN-PP 9.28 2.44 9.17 2.20 -0.11 -0.52 0.61(NS)
S-N-Pog 80.44 3.01 80.39 3.01 -0.06 -0.37 0.72(NS)
U1-PP 111.11 8.78 110.83 8.54 -0.28 -0.77 0.45(NS)
L1-MP 100.39 6.48 100.61 7.20 0.22 0.44 0.67(NS)
U1-L1 124.83 10.72 125.39 10.85 0.56 1.25 0.23(NS)
S-N 67.89 2.64 68.32 3.03 0.42 1.26 0.23(NS)
S-Ar 33.08 2.94 33.31 2.94 0.23 1.82 0.09(NS)
Go-Me 68.22 2.89 68.73 3.03 0.50 1.24 0.23(NS)
Ar-Go 45.21 6.22 45.42 6.12 0.21 1.34 0.20(NS)
TAFH 113.02 7.29 113.14 7.17 0.12 0.75 0.46(NS)
PFH 74.73 6.62 74.87 6.54 0.14 1.76 0.10(NS)
Table 1. Descriptive statistics and methods difference for the measured variables
Angular
Measurements
(°)
Orthodontics
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