Rapid Prototyping JournalError analysis of FDM fabricated medical replicasIhab El-Katatny S.H. Masood Y.S. Morsi

Article information:To cite this document:Ihab El-Katatny S.H. Masood Y.S. Morsi, (2010),"Error analysis of FDM fabricated medical replicas", Rapid Prototyping Journal,Vol. 16 Iss 1 pp. 36 - 43Permanent link to this document:http://dx.doi.org/10.1108/13552541011011695

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Error analysis of FDM fabricated medicalreplicas

Ihab El-Katatny, S.H. Masood and Y.S. Morsi

Faculty of Engineering and Industrial Science, Swinburne University of Technology, Melbourne, Australia

AbstractPurpose – Recent advancement in fused deposition modelling (FDM) rapid prototyping technology has made it a viable technology for application inreconstructive surgery. The purpose of this paper is to investigate the errors generated during the fabrication stage of complex anatomical replicasderived from computed tomography coupled with the technique of FDM.Design/methodology/approach – An evaluation on the errors generated during the fabrication process of two anatomical parts (skull or mandible)for different human sizes (infant, female or male) is carried out. A comparison between the linear measurements of 11 landmarks on the virtual modelof a skull and nine for the mandible of patient specific and its replica is conducted. Furthermore, eight landmarks are chosen to evaluate the bonethickness variation over the fabricated replicas.Findings – Although the FDM technology proved the ability to manufacture and to fit prosthesis to a patient’s unique proportions quickly and withrelatively low cost, the model accuracy is a key factor to the applicability of such technology. The results show undersized replicas with an overallabsolute average deviation of 0.24 per cent with an average standard deviation of 0.16 per cent of the skull models and 0.22 per cent with a0.11 per cent standard deviation of the mandibles. Furthermore, a high level of accuracy is reflected in the representation of the measured bonethickness with deviations in the order of 100th of a millimetre being reported.Originality/value – The paper demonstrates an outstanding accuracy using FDM process for the fabrication of anatomical replicas using models ofdifferent human sizes and gender in comparison to other established rapid prototyping techniques.

Keywords Rapid prototypes, Modelling, Human anatomy, Computer aided design, Error analysis

Paper type Research paper

1. Introduction

The rapid prototyping technology is becoming increasinglyimportant as a manufacturing method for many medicaldevices. Several studies were carried out in order to evaluatethe technology in comparison with traditional fabricationmethods. (Santler et al., 1998) carried out a comparison inregard to the production method and accuracy between twomodels produced by stereolithography (SLA) and milling.They concluded that both methods are sufficiently accuratefor clinical use. However, SLA replicas are preferable inspecial cases necessitating fine structures and complex internalgeometry. A similar conclusion was reached by Sarment et al.(2003) highlighting the use of Stereolithographic guidesallowing for improved implant placement where significantreduction to the average distance between the plannedimplants and actual osteotomies was reported in comparisonto the traditional surgical guidance methods.Although the advantage of such a technique is evident,

developing an understanding of the entire manufacturingprocess, starting from the image generation to the endproduct as well as identifying all possible sources of error isessential in assisting such techniques. In 1997, Bouyssie et al.

(1997) investigated the accuracy of complex anatomicalreplicas derived from X-ray computed tomography (CT) datalinked to the rapid prototyping techniques of SLA. In theirstudy, two mandible replicas were manufactured by SLA. Thedry mandibles were embedded in gelatin to reduce air-boneinterface and to simulate the presence of surrounding softtissues. Dimensional comparisons were undertaken betweennine landmarks both on the original bone and on its replica bythree different observers. Absolute and relative differenceswere calculated, relative differences being expressed aspercentages. They concluded that the differences betweenthe various measurements are either positive or negative,which indicate that the replica can be over or under-dimensioned. Absolute differences range from 0.0 to0.24mm. Globally, the original mandible is slightly morevoluminous than the replica, with a mean difference ofþ0.06mm. The average absolute difference is 0.12mm, witha standard mean error of 0.02mm reported.Another study carried out by Choi et al. (2002) examines

the effect of the threshold value on the accuracy of 3D virtualmodels as well as the errors generated during the productionof medical rapid prototyping (RP) models using SLAtechnique, etc. In their study, 12 landmarks were used forlinear measurement, eight for craniomaxillary and four for themandible. They concluded that the absolute mean deviationThe current issue and full text archive of this journal is available at

www.emeraldinsight.com/1355-2546.htm

Rapid Prototyping Journal

16/1 (2010) 36–43

q Emerald Group Publishing Limited [ISSN 1355-2546]

[DOI 10.1108/13552541011011695]

Support from Australian Research Council (ARC) under ARC Linkagegrant is gratefully acknowledged.

Received: 20 November 2008Revised: 9 April 2009Accepted: 14 April 2009

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between the original dry skull and the RP model over the 16

linear measurements was 0.62-0.35mm (0.56-0.39 per cent),

which is smaller than the values reported in previous studies.Furthermore, they developed a relationship called the “dumb-

bell” effect which describes that the effect of threshold valuedepending on whether a measurement is internal or external.

Although knowledge of the optimal threshold value is

important to enhance model accuracy, it cannot bedetermined from a limited number of RP models. A similar

investigation was carried by Nizam et al. (2006). Their studyof the dimensional accuracy of the skull models produced

using the rapid prototyping technology of SLA was aimed at

validating the system for clinical applications at HospitalUniversity Sains Malaysia. SLA technique was used to

fabricate a replica model of four dried human adult skulls.

Eight linear measurements were repeatedly made betweenidentified point landmarks on each of the original skulls and

its replica using an electronic digital caliper. They concludedthat the overall absolute difference between the four human

adult skulls and its replica models was 0.59mm with a

standard deviation of 0.89mm. Furthermore, the meanpercentage of 0.54 per cent with a standard deviation of 0.62

per cent was recorded.Meakin et al. (2004) evaluated the accuracy of a replica of a

sheep’s lumbar vertebra using data from a CT scan andutilising the fused deposition modelling (FDM) technique.

Vernier callipers and laser scanning techniques were used to

compare the measured data between the original and itsreplica. They concluded that apart from the spinous process

width, over five linear measurements, there was an absolutemean deviation of 1.36mm, and 0.77mm of absolute

standard deviation. Furthermore, in comparison to the

other rapid prototyping techniques a similar level ofaccuracy was achieved. Apart from the pervious study, the

primary focus was on the evaluation of selective laser sintering

(SLS) and SLA techniques. However, recent developments inusing poly(e-caprolactone) and other biocompatible material

in an FDM machine have opened the door for such atechnique to be widely used especially for scaffolds fabrication

in tissue engineering applications. While it is essential to

identify all possible sources of errors which may occur duringthe manufacturing process such as: errors generated during

medical imaging (Bouyssie et al., 1997) as well as the virtualmodel generation (Choi et al., 2002), the objective of this

study is to evaluate the accuracy in the fabrication stage of the

medical replica based on different human sizes and genderusing the rapid prototype technique of FDM.

2. Model fabrication

Figure 1 shows the overall production stages of skullfabrication using FDM technique. A 3D representation of

the craniomaxillary of a patient specific was generated usingInVesalius (2008) software. In order to differentiate the hard

tissues from the surrounding soft tissues a segmentation

technique with threshold values ranging between 1,200 and4,000 were applied. Upon completion of segmentation, data

is converted to an standard tessellation language (STL) fileformat which is imported to Materialise (2004) software. In

Magics software, the 3D volume of the patient’s

craniomaxillary was edited and distortions resulting frommetallic implants and errors due to partial volume effects were

corrected. Furthermore, morphology operations, Boolean

operations and cavity fill were used to generate a high-

resolution contour suitable for most rapid prototype

techniques.In the second step, Stratasys (2004) software was used to

prepare the model for fabrication. The model orientation was

chosen and a model support was created. A slice algorithm

was invoked and a tool-path plan was also generated. The

tool-path information was then converted into machine codes

for physical model fabrication. FDM3000 was used in the

replica fabrication with operating specifications as shown in

Table I. The replica was produced in a slice fashion using

ABS as the fabricated material and soluble support material.

The final stage involved the removal of the support material as

well as cleaning and polishing the product. The fabrication

procedure shown below refers to the male skull fabricated

replica. However, a similar process for different skull sizes

(female and infant) and mandibles (male, female and infant)

fabrication was conducted. Figure 2 shows the final fabricated

models of using FDM technique.

3. Dimensional analysis

Based on Garwin (2006), 11 pre-determined positions on the

cranium as well as nine mandible landmarks were selected for

linear measurement analysis. Table II shows the linear

measurement definition of these landmarks. Figure 3 shows

the physical locations of these landmarks. Furthermore, eight

landmarks were used to evaluate the accurate presentation of

bone thickness variations over the parts which were

Figure 1 Fabrication process of the skull replica using FDM3000

CT InVesalius software2 D slice image 3D render model Regain of interst

3D fabricated modelFDM 3,000

3D tool-path ModelInsight software

3D virtual modelMagics Software

Table I Operating specifications of FDM3000

Modeller: FDM 3000Model material ABS P400 Nozzle type: T12

Support material Soluble P400SR Nozzle type: T12

Slice height 0.2540 mm

Part fill style Perimeter/rasters Depth of contours 6.3500 mm

Part interior style Solid – fine Part interior depth 1.0160 mm

Contour width 0.5080 mm Part raster width 0.5080 mm

Error analysis of FDM fabricated medical replicas

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considered to be of the most important factors in evaluating

such a technique, especially with regard to bone replacement

as well as scaffold fabrication in tissue engineering. Table III

shows the definition of eight landmarks where comparison

between the thickness of replica and the virtual model were

conducted. Figure 4 shows the physical locations of these

landmarks.All linear measurements were carried out on the replica

using NSK MAX-Series Electronic Digital callipers. In

Magics software, a distance measurement function was used

to identify the linear measurements on the 3D virtual model

as shown in Figure 5. To guarantee ease and clarity for

measurements, and to avoid any possible errors resulting from

misrepresentation of point positioning, 2mm2 grooved holes

were punched into each of the landmark points. Furthermore,

to avoid the errors generated from the open profile of the

mandible, a 3mm rod was placed between the condyles.Linear distance between each identified landmark (left and

right) was measured by placing the digital calliper at the far

end corner of each groove. In order to reduce the possibility

of human error while taking the linear measurements on the

replica, an average of five measurements was considered in the

final analysis. An optimum scaling of the virtual model was

Figure 3 Linear measurements used in the comparison between the virtual models and its replicas

Coronal view of skull

alal 5

46 ec

zy

ft

eu

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10ba

87

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S3CC

JFSF

FOFS

16

14

15

13

12

cdl

go go

gn

2017

18

id

19 cdl

3

2

1

ft

eu

zy

ec

Axial view of skull Sagittal view of mandible Coronal view of mandible

Figure 2 3D fabricated replicas and virtual presentation

Infa

ntM

ale

Fem

ale

Virtual models Fabricated replicas Virtual models Fabricated replicas

Skull Mandible

Table II Anatomical landmarks definitions used for the linear measurement

No Abbrev Landmark name Definition

Skull1 eu-eu Maximum cranial breadth Maximum width of skull perpendicular to midsagitta

2 ft-ft Minimum frontal breadth Distance between the two frontotemporale (ft)

3 ec-ec Biorbital breadth Distance between right and left ectoconchion (ec)

4 zy-zy Bizygomatic diameter Distance between most lateral points on the zygomatic arches

5 al-al Nasal breadth Maximum breadth of the nasal aperture

6 Orbital height Distance between the superior and inferior orbital margins

7 Foramen magnum breadth Distance between the lateral margins of foramen magnum at the points of greatest lateral curvature

8 ba-o Foramen magnum length Distance from basion (ba) to opisthion (o)

9 Fo-fo Foramen ovale Distance between left and right of foramen ovale

10 Fs-fs Foramen spinosum Distance between left and right of foramen spinosum

11 Length of internal cranium Anteroposterior length of the bony internal cranium

Mandible12 Maximum ramus height Distance from the highest point on the mandibular condyle to gonion (go)

13 Maximum ramus breadth Distance between the most anterior point on the mandibular ramus

14 Mandibular length Distance of the anterior margin of the chin

15 Minimum ramus breadth Least breadth of the mandibular ramus measured perpendicular to the height of the ramus

16 Height of the mandibular body Distance from the alveolar process to the inferior border of the mandible

17 mf-mf Mental foramen Distance between the right and left mental foramen

18 go-go Bigonial width Distance between right and left gonion (go)

19 cdl-cdl Bicondylar breadth Distance between the most lateral points on the two condyles (cdl)

20 id-gn Chin height Distance from infradentale (id) to gnathion (gn)

Error analysis of FDM fabricated medical replicas

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utilised in order to produce a clear and accurate presentation

of the points of interest and liner distance values were

acquired at corresponding exact locations on the replica as

shown in Figure 5. Table IV shows each of linear

measurements on the virtual model and their replicas. Thedifference between the measurements is also presented in

terms of mm and percentages.

4. Results and discussion

Figure 6 shows the linear deviation of the skull models over 12

landmarks. The error values varied between minimum errorsof 0.02mm and a maximum error of 0.25mm with an average

deviation of 0.108mm. The deviation is reported to be in

the negative with an under-dimensioned representation of the

replica in comparison to the virtual model. Also, the figureshows that apart from a few scatter points the error is

concentrated in the range between 0.07 and 0.15mm with an

average deviation of 0.1mm.

With regard to the mandible study, similar observations

with an under-dimensioned representation of the replica incomparison to the virtual model were presented. Errors

ranged between a minimum of 0.035mm and maximum of0.2mm with an average of 0.079mm reported. Furthermore,the error over various landmarks was concentrated in the

range between 0.05 and 0.08mm as shown in Figure 7. Inaddition greater accuracy was achieved with the mandiblefabrication which had an average error in the order of a

hundredth of a millimetre, whereas the skull showed errors inthe order of a tenth of a millimetre.The influences of themeasured distance aswell as the shape of

the replicated organs on the errors generated during thefabrication stage were investigated. The fitted curves in

Figure 8 shows that the errors reported are random withrespect to the measured distance. In addition, the shape of thereplica has no influence in the fabricated errors where different

error trends for the samemedical organ were observed as shownin Figure 8(a) and (b).

Figure 4 Anatomical landmarks used for bone thickness measurement

Coronal view of skull Sagittal view of skull Coronal view of mandible

gn

gogo

cdl

I

cdl

zyzy

al al

eueu

ecec

Figure 5 Linear measurements of landmarks for the 3D virtual model

Coronal view of skull Axial view of skull Sagittal view of mandible Coronal view of mandible

Table III Anatomical landmark definitions used for bone thickness measurement

No Abbrev Landmark name Definition

Skull1 al Alare The most lateral points on the nasal aperture in a transverse plane

2 ec Ectoconchion The intersection of the most anterior surface of the lateral border of the orbit and a line bisecting the orbit along

its long axis

3 eu Euryon The points on opposite sides of the skull that form the termini of the line of greatest cranial breadth

4 l Lambda The ectocranial midline point where the sagittal and lambdoidal sutures intersect

5 zy Zygion Instrumentally determined as the most lateral point on the zygomatic arch

Mandible6 cdl Condylion laterale The most lateral point on the mandibular condyle

7 gn Gnathion The most inferior midline point on the mandible

8 go Gonion A point along the rounded posteroinferior corner of the mandible between the ramus and the body

Error analysis of FDM fabricated medical replicas

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With regard to the accuracy of bone thickness fabrication, as

shown in Figure 9, a high degree of accuracy of bone

thickness fabrication was observed. An average of less than

0.03mm deviation between the bone thickness of the replica

and its virtual model with the error ranges from 0.007 to

0.064mm were reported.Table V outlines the overall absolute difference between the

skull virtual model and its replicas were in the range between

0.21 and 0.27 per cent with a standard deviation ranging

between 0.12 and 0.2 per cent. With regard to the mandible

the overall absolute difference between the virtual model and

its replica are in the range of 0.15-0.32 per cent with a

standard deviation range between 0.08 and 0.14 per cent.

Furthermore, as shown in Table VI(a), a high level of

accuracy is reported with the reduction of absolute error

percentage to less than half in comparison with the errors

reported in the recent studies by Nizam et al. (2006) and

Choi et al. (2002). This was further reduced to almost one-

tenth in comparison with earlier studies by Kragskov et al.

(1996), Barker et al. (1994) and Lill et al. (1992). Despite

the majority of the studies being carried out on the

comparison between the dry skull and its fabricated replica,

the reduction of the errors remained in the vicinity of 50

per cent in comparison to that reported by Choi et al.

(2002). In his study, the errors between the virtual model

and its rapid prototype replica for the same landmark and

Figure 6 Linear deviations between the skull virtual models and replicas over 11 landmarks

Errors of the skull models fabrication

00.010.020.030.040.050.060.070.080.090.1

0.110.120.130.140.150.160.170.180.190.2

0.210.220.230.240.250.26

0 1 2 3 4 5 6 7 8 9 10 11 12

Landmarks no.

Err

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mm

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Infant Female Male

Table IV Mean and percentage of the absolute differences for the linear measurements

Infant Female Male

Virtual Replica

Absolute

difference Virtual Replica

Absolute

difference Virtual Replica

Absolute

difference

No mm mm mm % mm mm mm % mm mm mm %

Skull1 118.07 117.98 0.087 0.07 122.20 122.13 0.069 0.06 139.21 139.12 0.090 0.06

2 78.25 78.12 0.126 0.16 85.54 85.42 0.122 0.14 95.05 94.98 0.073 0.08

3 71.34 71.25 0.094 0.13 81.26 81.16 0.093 0.11 91.47 91.43 0.031 0.03

4 86.44 86.32 0.121 0.14 111.53 111.40 0.127 0.11 117.57 117.37 0.193 0.16

5 17.39 17.31 0.076 0.44 23.13 23.05 0.082 0.35 22.95 22.86 0.092 0.40

6 19.72 19.69 0.029 0.15 29.64 29.48 0.152 0.51 33.01 32.98 0.029 0.09

7 24.85 24.80 0.052 0.21 24.38 24.30 0.085 0.35 26.33 26.25 0.078 0.30

8 23.42 23.33 0.088 0.38 27.99 27.89 0.095 0.34 33.74 33.62 0.115 0.34

9 37.08 36.94 0.133 0.36 37.47 37.33 0.145 0.39 32.64 32.45 0.192 0.59

10 46.98 46.88 0.093 0.20 43.88 43.66 0.219 0.50 46.67 46.43 0.241 0.52

11 136.62 136.51 0.106 0.08 161.70 161.56 0.140 0.09 178.80 178.71 0.086 0.05

Mandible12 24.44 24.37 0.071 0.29 48.85 48.81 0.039 0.08 63.32 63.26 0.065 0.10

13 25.27 25.20 0.070 0.28 36.86 36.80 0.060 0.16 42.29 42.21 0.073 0.17

14 43.96 43.81 0.142 0.32 55.51 55.45 0.054 0.10 85.32 85.25 0.065 0.08

15 19.66 19.59 0.066 0.34 26.99 26.92 0.069 0.26 32.45 32.39 0.059 0.18

16 14.57 14.50 0.072 0.49 22.56 22.49 0.068 0.30 29.13 29.04 0.082 0.28

17 28.37 28.28 0.095 0.33 37.94 37.88 0.060 0.16 42.84 42.72 0.117 0.27

18 60.62 60.54 0.080 0.13 83.12 83.08 0.046 0.06 88.13 88.07 0.067 0.08

19 76.36 76.16 0.201 0.26 102.60 102.48 0.120 0.12 109.64 109.56 0.071 0.06

20 18.58 18.50 0.075 0.40 21.88 21.77 0.110 0.50 30.20 30.15 0.041 0.14

Error analysis of FDM fabricated medical replicas

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measurement techniques were also found and compared as

reported in Table VI(b).

5. Conclusion

Studies on the skull showed an average of absolute mean

differences of 0.108mm (0.24 per cent) and average standard

deviations of 0.048mm (0.16 per cent). There was a similar

range of errors with regarded to the mandible replicas

showing an average absolute mean difference of 0.079mm(0.22 per cent) and an average standard deviation of

0.031mm (0.11 per cent). Furthermore, a high level ofaccuracy with the regard to the bone thickness fabrication was

recorded with errors in the range of a hundredth of amillimetre. The fabricated replicas demonstrated negative

presentations in comparison to the virtual models with

Figure 8 Relationship between the error and measured distance for skull (a) and mandible (b) models

The relationship between errors and linear measurement of the skull models fabrication

00.010.020.030.040.050.060.070.080.090.1

0.110.120.130.140.150.160.170.180.190.2

0.210.220.230.240.250.26

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190

Linear measurement (mm)

Err

or (

mm

)

Infant Female Male

The relationship between errors and linear measurement of the mandible models fabrication

00.010.020.030.040.050.060.070.080.090.1

0.110.120.130.140.150.160.170.180.190.2

0.210.22

0 10 20 30 40 50 60 70 80 90 100 110 120

Linear measurement (mm)

Err

or (

mm

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(a) (b)

Figure 7 Linear deviations between the mandible virtual models and replicas over six landmarks

Errors of the mandible models fabrication

00.010.020.030.040.050.060.070.080.090.1

0.110.120.130.140.150.160.170.180.190.2

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11 12 13 14 15 16 17 18 19 20 21

Landmarks no.

Err

or (

mm

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Infant Female Male

Figure 9 Linear deviation of bone thickness fabrication for skull and mandible replicas

Errors of the skull and mandible models fabrication

00.0020.0040.0060.0080.01

0.0120.0140.0160.0180.02

0.0220.0240.0260.0280.03

0.0320.0340.0360.0380.04

0.0420.0440.0460.0480.05

0.0520.0540.0560.0580.06

0.0620.064

al ec eu l ez cdl gn go

Landmarks

Err

or (

mm

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Infant skull Female skull

Male skull Infant mandibleMale mandible Man mandible

Error analysis of FDM fabricated medical replicas

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under-sized replicas over all the linear measurementsobserved. The anatomical parts (skull or mandible) as wellas the replicated size (infant, male and female) seem to havenot much influence on the fabrication accuracy using FDMtechnique. Outstanding fabrication accuracy in comparison toother rapid prototype technology was demonstrated.Furthermore, the use of FDM technique in the fabricationof various anatomical parts to a high level of accuracy isevident.

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models for evaluation of craniofacial anomalies”, Journal

of Oral and Maxillofacial Surgery, Vol. 54 No. 4, pp. 402-12.Lill, W., Solar, P., Ulm, C., Watzek, G., Blahout, R. and

Matejka, M. (1992), “Reproducibility of three-dimensional

CT-assisted model production in the maxillofacial area”,

British Journal of Oral and Maxillofacial Surgery, Vol. 30

No. 4, pp. 233-6.Materialise (2004), Magics v9.9, Materialise, Leuven,

available at: www.materialise.com/magicsMeakin, J.R., Shepherd, D.E.T. and Hukins, D.W.L. (2004),

“Fused deposition models from CT scans”, British Journal

of Radiology, Vol. 77 No. 918, pp. 504-7.Nizam, A., Gopal, R.N., Naing, L., Hakim, A.B. and

Samsudin, A.R. (2006), “Dimensional accuracy of the skull

models produced by rapid prototyping technology using

stereolithography apparatus”, Orofacial Sciences, Vol. 1,

pp. 60-6.Santler, G., Karcher, H., Gaggl, A. and Kern, R. (1998),

“Stereolithography versus milled three-dimensional models:

comparison of production method, indication, and

accuracy”, Computer Aided Surgery, Vol. 3 No. 5, pp. 248-56.Sarment, D.P., Sukovic, P. and Clinthorne, N. (2003),

“Accuracy of implant placement with a stereolithographic

surgical guide”, International Journal of Oral and

Maxillofacial Implants, Vol. 18 No. 4, pp. 571-7.Stratasys (2004), Insight, V3.1, Stratasys, Eden Prairie, MN,

available at: www.stratasys.com

Table VI Previous study results compared with current study results

Mean of absolute

difference

Standard deviation of

absolute difference

Comparison models mm % mm %

(a)

Our study Skull virtual model – FDM replica 0.11 0.24 0.05 0.16

Nizam et al. (2006) Dry skull – SLA replica 0.59 0.54 0.89 0.62

Choi et al. (2002) Dry skull – SLA replica 0.62 0.56 0.53 0.39

Kragskov et al. (1996) 3D CT image – SLA replica 1.98 3.59 1.2 2.67

Barker et al. (1994) Dry skull – SLA replica 1.90 2.54 1.48 1.38

Lill et al. (1992) Dry skull – milled replica 1.47 2.19 0.94 1.37

(b)

Our study Skull virtual model – FDM replica 0.11 0.24 0.05 0.16

Choi et al. (2002) Skull virtual model – SLA replica 0.57 0.82 0.62 0.52

Table V Overall mean and percentage differences between the virtual model and its replica

Skull Mandible

Mean of absolute

difference

Standard deviation

of absolute

difference

Mean of absolute

difference

Standard deviation

of absolute

difference

mm % mm % mm % mm %

Infant 0.091 0.21 0.031 0.12 0.097 0.32 0.046 0.10

Female 0.121 0.27 0.043 0.17 0.070 0.19 0.028 0.14

Male 0.111 0.24 0.069 0.20 0.071 0.15 0.021 0.08

Average 0.108 0.24 0.048 0.16 0.079 0.22 0.031 0.11

Error analysis of FDM fabricated medical replicas

Ihab El-Katatny, S.H. Masood and Y.S. Morsi

Rapid Prototyping Journal

Volume 16 · Number 1 · 2010 · 36–43

42

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About the authors

Ihab El-Katatny is a Research Engineer at Faculty ofEngineering and Industrial Sciences at Swinburne Universityof Technology. His research interests are in rapid prototyping,reconstructive surgery and computational fluid dynamics.

S.H. Masood is a Professor of Manufacturing Engineering atSwinburne University of Technology. He is the ProgramCoordinator of Postgraduate Programs in AdvancedManufacturing Technology at Swinburne. His research

interests are in rapid prototyping, fused deposition

modelling, rapid manufacturing, tissue engineering scaffolds

and CAD/CAM. S.H. Masood is the corresponding author

and can be contacted at: smasood@swin.edu.au

Y.S. Morsi is a Professor of Mechanical Engineering and

leader of Biomechanics and Tissue engineering research

group at Swinburne University of Technology. His research

interests are in biomedical devices, biomechanics, tissue

engineering and nanofabrication.

Error analysis of FDM fabricated medical replicas

Ihab El-Katatny, S.H. Masood and Y.S. Morsi

Rapid Prototyping Journal

Volume 16 · Number 1 · 2010 · 36–43

43

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