RESEARCH AND EDUCATION
Analysis o he impac o he acial scanning me hod
on he p ecision o a i ual acebow eco d echnique:
An in i o s udy
Xabie Amezua, BEng, MSc,
a
Mikel I u a e, BEng, MSc, PhD,
b
Xabie Ga ikano, BEng, MSc, PhD,
b
and
Eneko Solabe ie a, BEng, MSc, PhD
c
ABSTRACT
S a emen o p oblem. Vi ual acebow eco d echniques ypically eco d he ela ionship o a maxilla y digi al scan o acial landma ks by
aligning i o a 3-dimensional ace scan. Th ee-dimensional ace scans can be acqui ed wi h di e en acial scanning me hods, bu he impac
o he acial scanning me hod on he accu acy ( ueness and p ecision) o a i ual acebow eco d echnique emains unclea .
Pu pose. The pu pose o his in i o s udy was o assess he impac o he acial scanning me hod on he p ecision unde he epea abili y
condi ions ( epea abili y) o a i ual acebow eco d echnique.
Ma e ial and me hods. Repea abili y o he i ual acebow eco d echnique wi h he ollowing 3 clinical-g ade acial scanning me hods was
de e mined and compa ed: a p o essional handheld scanne based on s uc u ed blue ligh scanning echnology (PHS me hod); an
a achmen - ype 3-dimensional senso came a connec ed o a able and con olled wi h a mobile applica ion (3DSC-T me hod); and a
sma phone wi h an in eg a ed 3-dimensional senso came a con olled wi h a mobile applica ion (3DSC-S me hod). To de e mine he
epea abili y o he i ual acebow eco d echnique wi h each acial scanning me hod, 8 i ual acebow eco ds o a comple ely
den a e adul wi h class I occlusion and mesop osopic acial o m we e ob ained (8×3=24 in o al); wi h hese, 8 loca ions o a maxilla y
digi al scan wi h espec o a common 3-dimensional ace scan we e ob ained. Repea abili y was de e mined in e ms o de ia ions
be ween loca ed maxilla y digi al scans, de e mined, in u n, by calcula ing he dis ances be ween co esponding e ices o each o he
possible non epea ing combina ions o pai s o loca ed maxilla y digi al scans (
8
C
2
=28). Finally, he epea abili y o he i ual acebow
eco d echnique wi h he di e en acial scanning me hods was compa ed by using he Welch ANOVA es and he pos hoc Games-
Howell es (bo h
a
=.05).
Resul s. The epea abili y o he i ual acebow eco d echnique wi h PHS, 3DSC-T, and 3DSC-S acial scanning me hods esul ed in 0.243
±0.094 mm, 0.437 ±0.171 mm, and 1.023 ±0.399 mm, espec i ely. Compa ison o hese esul s e ealed ha he acial scanning me hod had a
s a is ically significan e ec on he epea abili y o he i ual acebow eco d echnique (P<.001) and ha i s epea abili y was s a is ically
significan ly g ea e wi h he PHS acial scanning me hod han wi h he 3DSC-T and 3DSC-S acial scanning me hods and g ea e wi h he
3DSC-T acial scanning me hod han wi h he 3DSC-S acial scanning me hod (P<.001 o all pai wise compa isons).
Conclusions. This s udy ound ha he acial scanning me hod had a g ea impac on he epea abili y o he i ual acebow eco d
echnique and ha he i ual acebow eco d echnique was mo e epea able wi h mo e accu a e acial scanning me hods. (J P os he
Den 2023;130:382-91)
Suppo ed by MINECO Minis y o Economy and Compe i i eness, Spain (g an numbe PID2019-108975RA-I00).
a
Resea ch Assis an , Depa men o G aphic Design and Enginee ing P ojec s, Facul y o Enginee ing Gipuzkoa, Uni e si y o he Basque Coun y UPV/EHU, San Sebas ian,
Spain.
b
Assis an P o esso , Depa men o G aphic Design and Enginee ing P ojec s, Facul y o Enginee ing Gipuzkoa, Uni e si y o he Basque Coun y UPV/EHU, San Sebas ian,
Spain.
c
Associa e P o esso , Depa men o G aphic Design and Enginee ing P ojec s, Facul y o Enginee ing Gipuzkoa, Uni e si y o he Basque Coun y UPV/EHU, San Sebas ian,
Spain.
382 THE JOURNAL OF PROSTHETIC DENTISTRY
In den al compu e -aided design and compu e -aided
manu ac u ing (CAD-CAM) sys ems, i ual a icula o s
a e used o subs i u e o complemen mechanical a ic-
ula o s.
1
As mos o hese i ual a icula o s ha e
s uc u es and wo king p inciples simila o hose o
mechanical a icula o s, adequa e moun ing o digi al
scans o den al a ches is a p e equisi e o simula ing
indi idual jaw mo emen s as ealis ically as possible.
The e o e, se e al echniques o moun ing digi al scans
o den al a ches o i ual a icula o s ha e been de el-
oped,
2
including i ual acebow (VF) echniques.
3-9
A VF echnique is a digi al al e na i e o a acebow
and as such is used o moun a maxilla y digi al scan o
a i ual a icula o acco ding o he ela ionship o he
maxilla y a ch o some ana omic e e ence poin o
poin s. The mos used VF echniques consis fi s ly o
eco ding he ela ionship o he maxilla y digi al scan o
some acial landma ks and hen moun ing i on he
i ual a icula o acco ding o his ela ionship.
7-9
To
ob ain such a ela ionship, a VF eco d ha in ol es
aligning he maxilla y digi al scan o one o mo e 3-
dimensional (3D) ace scans is made. The e o e, an
accu a e moun ing o a maxilla y digi al scan in a i ual
a icula o h ough hese VF echniques equi es, among
o he hings, an accu a e VF eco d. Di e en VF eco d
echniques a e a ailable,
7-15
bu hei accu acy has been
li le s udied.
16-18
The accu acy o a VF eco d echnique e e s o i s
abili y o p o ide co ec and epea able loca ions o a
maxilla y digi al scan wi h espec o a 3D ace scan.
Acco ding o he In e na ional O ganiza ion o S an-
da diza ion (ISO) s anda d 5725-1,
19
accu acy is a com-
bina ion o ueness and p ecision, wi h ueness
e e ing o he abili y o he VF eco d echnique o
loca e a maxilla y digi al scan o a 3D ace scan as close o
i s eal posi ion as possible and p ecision o he closeness
o ag eemen be ween independen loca ions o a
maxilla y digi al scan o a 3D ace scan p o ided by he
VF eco d echnique unde s ipula ed condi ions. In his
ega d, a p e ious in i o s udy ound ha he accu acy
o a VF eco d echnique was s ongly influenced by he
acial scanning me hod used and ha he VF eco d
echnique was mo e accu a e, wi h mo e accu a e acial
scanning me hods.
18
P e ious s udies ha e e alua ed he accu acy o
di e en acial scanning me hods, concluding ha he
mos accu a e a e s a iona y acial scanning sys ems
based on s e eopho og amme y scanning echnol-
ogy.
20
,
21
Howe e , hei cos , size, complexi y, and lack o
po abili y may limi he clinical adop ion o hese sys-
ems.
20
,
21
Al e na i ely, p o essional handheld scanne s,
whose accu acy has been shown o be compa able wi h
hose o s a iona y acial scanning sys ems, a e a ail-
able.
22-24
Low-cos and easy- o-use al e na i es a e also
a ailable,
25
,
26
including 3D senso came as based on
s uc u ed ligh scanning echnology.
26-28
Ini ially, hese
3D senso came as we e o he accesso y ype and we e
connec ed o sma phones, able s, o lap op com-
pu e s.
26
,
27
Howe e , mo e ecen ly, hese 3D senso
came as ha e also been in eg a ed in o some sma -
phones and able s.
28
The accu acy o hese 3D senso
came as is no compa able wi h ha o p o essional
handheld scanne s bu has been epo ed o be clinically
accep able.
21
,
28
Ne e heless, he accu acy o VF eco d
echniques wi h hese clinical-g ade acial scanning
me hods emains unclea .
The pu pose o his in i o s udy was o assess he
impac o he acial scanning me hod on he p ecision
unde epea abili y condi ions ( epea abili y) o a VF e-
co d echnique. The null hypo hesis was ha no di e -
ence would be ound in he epea abili y o he VF eco d
echnique when using di e en acial scanning me hods.
MATERIAL AND METHODS
Repea abili y o a VF eco d echnique (AFT Sys em One;
AFT Den al Sys em, SL) wi h 3 di e en clinical-g ade
acial scanning me hods was de e mined and
compa ed. The selec ed 3 acial scanning me hods we e a
p o essional handheld scanne based on s uc u ed blue
ligh scanning echnology (A ec Space Spide ; A ec 3D,
SARL) (PHS me hod); an a achmen - ype 3D senso
came a (Bellus3D Face Came a P o; Bellus3D, Inc) con-
nec ed o a able (Huawei MediaPad M3; Huawei
Technologies Co, L d) and con olled wi h a mobile
applica ion (Bellus3D Face Came a App; Bellus3D, Inc)
(3DSC-T me hod); and a sma phone wi h an in eg a ed
3D senso came a (iPhone X; Apple, Inc) con olled wi h
a mobile applica ion (Bellus3D FaceApp; Bellus3D, Inc)
(3DSC-S me hod).
A comple ely den a e 22-yea -old man wi h class I
occlusion and mesop osopic acial o m was ec ui ed.
The s udy was app o ed by he uni e si y e hical com-
mi ee (M10_2019_254), and acco ding o local and in-
e na ional e hical ules, he pa icipan signed an
in o med consen o m be o e en ollmen in he s udy.
An in ao al scan o he pa icipan ’s maxilla y a ch
was made by using an in ao al scanne (TRIOS 3;
3Shape A/S) by ollowing he manu ac u e ’s scanning
Clinical Implica ions
The acial scanning me hod had a g ea impac on
he abili y o a i ual acebow eco d echnique o
p o ide epea able loca ions o a maxilla y digi al
scan wi h espec o a 3-dimensional ace scan.
Clinicians need o be awa e o his when selec ing
he acial scanning me hod.
Sep embe 2023 383
Amezua e al THE JOURNAL OF PROSTHETIC DENTISTRY
s a egy. This was pe o med by an expe ienced ope a o ,
wi h he pa icipan posi ioned in a den al chai a a
esea ch labo a o y wi h only ceiling ligh ing. A maxilla y
digi al scan was ob ained in he s anda d essella ion
language (STL) file o ma (Fig. 1), which was hen
loaded in o a e e se enginee ing so wa e p og am
(Geomagic S udio 2013; Geomagic, Inc) in conjunc ion
wi h a 20-mm edge cube, p e iously designed by using
an enginee ing CAD so wa e p og am (Solid Edge;
Siemens AG). The maxilla y digi al scan was o ien ed
wi h espec o he cube, and he se was expo ed in he
STL file o ma o subsequen use (Fig. 2).
An in ao al ans e elemen (IOTE) and a acial
ans e elemen (FTE) we e hen placed on he pa ici-
pan : he FTE on he pa icipan ’s o ehead, well
cen e ed, and he IOTE in he pa icipan ’s mou h,
a ached fi mly o he lip and s abilized wi h high- and
low- iscosi y poly inyl siloxane imp ession ma e ial
(Aquasil So Pu y and Aquasil Ul a LV; Den sply
Si ona). In addi ion, a small poin was d awn on he
pa icipan ’s nose wi h an ul afine, black pe manen
ma ke (BIC Ma king; BIC, Inc) by ollowing he bipu-
pilla y line as a e e ence.
Wi h he FTE and IOTE in place, 8 epea ed acial
scans we e made wi h each o he 3 acial scanning
me hods (Fig. 3). All scans we e pe o med wi h he
pa icipan sea ed in an adjus able o a y chai , and, o
ensu e epea abili y condi ions, hey we e pe o med by
he same expe ienced ope a o in he same esea ch
labo a o y and wi hin a sho ime, lea ing a ew seconds
be ween scans and changing he acial scanning me hod
in andom o de a e e e y 4 scans. Scans wi h he PHS
me hod we e pe o med by mo ing he scanne manu-
ally a ound he pa icipan ’s ace a a dis ance o be ween
20 and 30 cm, and, in con as wi h he 3DSC-T and
3DSC-S me hods, by posi ioning he co esponding
mobile de ice ( he able wi h he 3D senso came a
a ached and he sma phone, espec i ely) on a fixed
suppo a a dis ance o be ween 30 and 45 cm om he
pa icipan ’s ace and by o a ing he chai acco ding o
he ins uc ions gi en by he mobile applica ion. Each
scan wi h he PHS me hod ook app oxima ely 40 sec-
onds, whe eas wi h he 3DSC-T and 3DSC-S me hods,
20 seconds. As a esul , 24 3D ace scans (named e e -
ence ace scans) we e ob ained in he objec (OBJ) file
o ma (Fig. 3B, D, F).
Subsequen ly, he IOTE was emo ed om he mou h,
main aining he FTE in he same posi ion. Then, a acial
scan was pe o med wi h he pa icipan a he es posi-
ion by using each o he 3 acial scanning me hods (Fig. 4).
This esul ed in h ee 3D ace scans (named es ace
scans) in he OBJ file o ma (Fig. 4B, D, F). The IOTE was
hen scanned by using a labo a o y scanne (E2; 3Shape
A/S). Fo ha , he imp ession a ea was coa ed wi h
scanning powde (Sp ay Scan Schmid Line; Hen y
Schein, Inc). As a esul , he digi al scan o he IOTE was
ob ained in he STL file o ma (Fig. 5).
A e comple ion o all scans, he pa icipan ’sVF
eco ds we e ob ained. Fo ha , each o he 8 e e ence
ace scans acqui ed wi h each o he 3 acial scanning
me hods was impo ed sepa a ely in o a den al CAD
so wa e p og am (exocad; exocad GmbH) in
conjunc ion wi h he es ace scan acqui ed wi h he
same acial scanning me hod, he maxilla y digi al
scan, and he digi al scan o he IOTE. The e, he
maxilla y digi al scan was aligned o he es ace scan,
keeping he es ace scan fixed. This was accomplished
by ollowing he alignmen p ocedu e es ablished by
he VF eco d echnique in e e se o de (Fig. 6): fi s ,
he e e ence ace scan was aligned o he es ace
scan (Fig. 6A); hen, he digi al scan o he IOTE was
aligned o he e e ence ace scan (Fig. 6B); and finally,
he maxilla y digi al scan was aligned o he digi al
scan o he IOTE (Fig. 6C). Thus, 3 g oups o 8
epea ed VF eco ds we e ob ained, which we e named
acco ding o he acial scanning me hod used o ob ain
Figu e 2. Maxilla y digi al scan aligned o cube.Figu e 1. Maxilla y digi al scan.
384 Volume 130 Issue 3
THE JOURNAL OF PROSTHETIC DENTISTRY Amezua e al
he 3D ace scans: PHS, 3DSC-T, and 3DSC-S. In his
way, in each o he 8 VF eco ds belonging o he same
g oup, a spa ial loca ion o he maxilla y digi al scan
was ob ained wi h espec o a common es ace scan.
F om each VF eco d, he loca ed maxilla y digi al scan
was expo ed in he STL file o ma . In each g oup,
each loca ed maxilla y digi al scan was labeled as
VFR_i (i=1 o 8).
Then, o each g oup, he de ia ion be ween pai s o
loca ed maxilla y digi al scans was de e mined o all
possible pai combina ions wi hou epe i ion (
8
C
2
=28).
To de e mine he de ia ion be ween a pai o loca ed
maxilla y digi al scans, gi en ha a maxilla y digi al scan
is a polygonal mesh and ha he loca ed maxilla y digi al
scans a e copies o he same maxilla y digi al scan a
di e en spa ial loca ions, dis ances be ween
Figu e 3. Acquisi ion o e e ence ace scans wi h di e en acial scanning me hods. A, Re e ence acial scan wi h PHS acial scanning me hod.
B, Re e ence ace scan acqui ed wi h PHS acial scanning me hod. C, Re e ence acial scan wi h 3DSC-T acial scanning me hod. D, Re e ence ace scan
acqui ed wi h 3DSC-T acial scanning me hod. E, Re e ence acial scan wi h 3DSC-S acial scanning me hod. F, Re e ence ace scan acqui ed wi h
3DSC-S acial scanning me hod.
Sep embe 2023 385
Amezua e al THE JOURNAL OF PROSTHETIC DENTISTRY
co esponding e ices we e calcula ed as a dis ance map
by using he me hodology desc ibed by Amezua e al.
18
Acco ding o his me hodology, each pai o loca ed
maxilla y digi al scans was loaded sepa a ely in o a 3D
inspec ion so wa e p og am (GOM Inspec 2019; GOM
GmbH). The e, a coo dina e sys em was c ea ed on each
by using he a ached cube (Fig. 7): he coo dina e sys em
ðOAXYZÞAon one (he eina e loca ed maxilla y digi al
scan A) and he coo dina e sys em ðOBUVWÞBon he
o he (he eina e loca ed maxilla y digi al scan B). Once
he coo dina e sys ems we e c ea ed, he componen s
o he homogeneous ans o ma ion ma ix A
BT ha de-
fines he loca ion o he coo dina e sys em ðOBUVWÞB
wi h espec o he coo dina e sys em ðOAXYZÞAwe e
Figu e 4. Acquisi ion o es ace scans wi h di e en acial scanning me hods. A, Res acial scan wi h PHS acial scanning me hod. B, Res ace scan
acqui ed wi h PHS acial scanning me hod. C, Res acial scan wi h 3DSC-T acial scanning me hod. D, Res ace scan acqui ed wi h 3DSC-T acial
scanning me hod. E, Res acial scan wi h 3DSC-S acial scanning me hod. F, Res ace scan acqui ed wi h 3DSC-S acial scanning me hod.
386 Volume 130 Issue 3
THE JOURNAL OF PROSTHETIC DENTISTRY Amezua e al
ob ained: A
BT=2
6
6
4
cðU;XÞ
cðU;YÞ
cðV;XÞ
cðV;YÞ
cðW;XÞ
cðW;YÞ
dx
dy
cðU;ZÞ
0
cðV;ZÞ
0
cðW;ZÞ
0
dz
1
3
7
7
5
,
whe e dx,dy,anddz ep esen he componen s o he
ec o dlinking he o igin o he coo dina e sys em
ðOAXYZÞAwi h he o igin o he coo dina e sys em
ðOBUVWÞBand he cðj;kÞ(j=U,V,Wand k=X,Y,Z)
ep esen he cosines o he angles o med by he axes U,
V, and Wo he coo dina e sys em ðOBUVWÞBwi h each
o he axes X,Y, and Zo he coo dina e sys em
ðOAXYZÞA. A e wa d, he x, y,and zcomponen s o
he posi ion ec o o each o he 144156 P e ices o
he loca ed maxilla y digi al scan A(among which he
e ices co esponding o he cube we e no included)
we e expo ed (Fig. 7) in Ame ican s anda d code o
in o ma ion in e change (ASCII) file o ma . This file was
hen loaded in o a sp eadshee so wa e p og am
(Mic oso Excel; Mic oso Co p), whe e he ollowing
sys em o ma ix equa ions was applied o each o he
posi ion ec o s o he e ices o he loca ed maxilla y
digi al scan A o ob ain he 0
x, 0
y, and 0
zcomponen s o
he posi ion ec o 0o hei co esponding e ices o
he loca ed maxilla y digi al scan Bwi h espec o he
ðOAXYZÞAcoo dina e sys em (Fig. 7):
8
>
>
>
>
>
<
>
>
>
>
>
:
0
x
0
y
0
z
1
9
>
>
>
>
>
=
>
>
>
>
>
;
=A
BT
8
>
>
>
>
>
<
>
>
>
>
>
:
x
y
z
1
9
>
>
>
>
>
=
>
>
>
>
>
;
.
Once all he posi ion ec o s 0we e ob ained, he dis-
ance map was ob ained by calcula ing he Euclidean
dis ances dPbe ween he co esponding e ices (Fig. 7).
Thus, epea ing his me hodology o all pai s o loca ed
maxilla y digi al scans, 28 dis ance maps we e ob ained
o each g oup, each comp ising 144 156 dis ances
(Fig. 8).
The dis ance da a we e loaded in o a s a is ical so -
wa e p og am (IBM SPSS S a is ics, 26; IBM Co p).
The e, he epea abili y o he VF eco d echnique wi h
di e en acial scanning me hods was de e mined and
compa ed. Fo ha , in each g oup, he mean o e ex-
o- e ex dis ances was calcula ed o each dis ance
map (Fig. 9). The epea abili y o he VF eco d echnique
wi h each acial scanning me hod was de e mined in
e ms o mean e ex- o- e ex dis ances wi hin each
g oup and exp essed, in u n, as hei mean ±s anda d
de ia ion (Table 1) because he Shapi o-Wilk es (
a
=.05)
e ealed ha in each g oup he mean e ex- o- e ex
dis ances we e no mally dis ibu ed. To compa e he
epea abili y o he VF eco d echnique (dependen
a iable) wi h di e en acial scanning me hods (inde-
penden a iable), he Welch ANOVA and he pos hoc
Games-Howell es (bo h
a
=.05) (Table 2) we e used, as,
despi e he assump ion o no mali y being me , he
Le ene es (
a
=.05) showed ha homogenei y o a i-
ances could no be assumed. In addi ion, Games-Howell
pai wise compa isons ha de ec ed a s a is ically signi -
ican di e ence we e accompanied by Cohen d e ec size
measu e, which de e mined he magni ude o such a
di e ence (Table 2).
29
A pos hoc powe analysis was also
pe o med in ano he s a is ical so wa e p og am (R
4.04; R Founda ion o S a is ical Compu ing) o assess
whe he he sample size (n=28) was adequa e o es he
null hypo hesis.
30
RESULTS
The de ia ions be ween he epea ed loca ions o he
maxilla y digi al scan p o ided by he VF eco d ech-
nique wi h he PHS, 3DSC-T, and 3DSC-S acial scan-
ning me hods anged om 0.041 mm o 0.550 mm, om
0.092 mm o 0.962 mm, and om 0.219 mm o 3.074 mm,
espec i ely (Fig. 8). Wi h hese de ia ions, he epea -
abili y o he VF eco d echnique wi h he PHS, 3DSC-T,
and 3DSC-S acial scanning me hods esul ed in 0.243
±0.094 mm, 0.437 ±0.171 mm, and 1.023 ±0.399 mm,
espec i ely (Table 1).
The Welch ANOVA es de ec ed ha he acial
scanning me hod used had a s a is ically significan e ec
on he epea abili y o he VF eco d echnique (Welch’sF
[2, 45.226]= 58.652, P<.001), whe eas he pos hoc powe
analysis e ealed a es powe alue equal o 1, con-
fi ming ha he sample size (n=28) was adequa e o es
he null hypo hesis. The Games-Howell pos hoc es
indica ed ha he epea abili y o he VF eco d ech-
nique was s a is ically significan ly g ea e wi h he PHS
acial scanning me hod han wi h he 3DSC-T and
3DSC-S scanning me hods and wi h he 3DSC-T scan-
ning me hod han wi h he 3DSC-S scanning me hod
(Table 2). Fu he mo e, acco ding o he Cohen d mea-
su e o e ec size, he magni ude o he s a is ically
Figu e 5. Digi al scan o IOTE. IOTE, in ao al ans e elemen .
Sep embe 2023 387
Amezua e al THE JOURNAL OF PROSTHETIC DENTISTRY
significan di e ence de ec ed in hese 3 pai wise com-
pa isons was e y la ge (d>0.8) (Table 2).
29
DISCUSSION
The esul s indica ed ha he epea abili y o he VF e-
co d echnique was di e en wi h di e en acial scan-
ning me hods, wi h s a is ical significance; hence, he
null hypo hesis was ejec ed. The esul s also indica ed
ha he epea abili y o he VF eco d echnique was
s a is ically significan ly g ea e wi h he PHS acial
scanning me hod han wi h he 3DSC-T and 3DSC-S
acial scanning me hods and wi h he 3DSC-T acial
scanning me hod han wi h he 3DSC-S acial scanning
me hod (Tables 1 and 2).
P e ious s udies ha e also analyzed he epea abili y
o his ype o VF eco d echnique,
17
,
18
bu a quan i a i e
compa ison among s udies is no possible because o
me hodological he e ogenei y. Ne e heless, he esul s
ob ained in he p esen s udy we e consis en wi h hose
o a p e ious s udy
18
because hey e ealed ha he
acial scanning me hod had a g ea impac on he
Figu e 7. Schema ic o calcula ion o dis ances be ween co esponding
e ices.
Figu e 6. Alignmen o maxilla y digi al scan o es ace scan. A, Alignmen o e e ence ace scan o es ace scan. B, Alignmen o digi al scan o IOTE
o e e ence ace scan. C, Alignmen o maxilla y digi al scan o digi al scan o IOTE. D, Resul o alignmen .
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THE JOURNAL OF PROSTHETIC DENTISTRY Amezua e al
epea abili y o he VF eco d echnique and ha i s
epea abili y was g ea e wi h mo e accu a e acial
scanning me hods. This is because, acco ding o p e ious
s udies ega ding he accu acy o acial scanning
me hods, PHS- ype acial scanning me hods a e mo e
accu a e han 3DSC-T- and 3DSC-S- ype me hods.
21
The au ho s a e unawa e o a p e ious s udy compa ing
he accu acy o 3DSC-T- and 3DSC-S- ype acial scan-
ning me hods, bu he esul s o he p esen s udy sug-
ges ha 3DSC-T- ype me hods a e mo e accu a e han
3DSC-S- ype me hods. Howe e , u he s udies a e
needed o e i y his.
Acco ding o ISO s anda d 5725-1, he epea abili y o
a VF eco d echnique can be defined as he ex eme o i s
p ecision desc ibing he minimum a iabili y o he lo-
ca ions o maxilla y digi al scans wi h espec o he 3D
ace scans i p o ides.
19
The e o e, and conside ing ha
o his s udy VF eco ds o a comple ely den a e adul
wi h class I occlusion and mesop osopic acial o m we e
made by an expe ienced ope a o in a esea ch
Pai Combina ion A
B
C
Pai Combina ion
VFR_1-VFR_2
VFR_1-VFR_3
VFR_1-VFR_4
VFR_1-VFR_5
VFR_1-VFR_6
VFR_1-VFR_7
VFR_1-VFR_8
VFR_2-VFR_3
VFR_2-VFR_4
VFR_2-VFR_5
VFR_2-VFR_6
VFR_2-VFR_7
VFR_2-VFR_8
VFR_3-VFR_4
VFR_3-VFR_5
VFR_3-VFR_6
VFR_3-VFR_7
VFR_3-VFR_8
VFR_4-VFR_5
VFR_4-VFR_6
VFR_4-VFR_7
VFR_4-VFR_8
VFR_5-VFR_6
VFR_5-VFR_7
VFR_5-VFR_8
VFR_6-VFR_7
VFR_6-VFR_8
0.0
0.1
0.2
0.3
0.4
0.5
0.6
VFR_7-VFR_8
Ve ex- o-Ve ex
Dis ance (mm)
Ve ex- o-Ve ex
Dis ance (mm)
VFR_1-VFR_2
VFR_1-VFR_3
VFR_1-VFR_4
VFR_1-VFR_5
VFR_1-VFR_6
VFR_1-VFR_7
VFR_1-VFR_8
VFR_2-VFR_3
VFR_2-VFR_4
VFR_2-VFR_5
VFR_2-VFR_6
VFR_2-VFR_7
VFR_2-VFR_8
VFR_3-VFR_4
VFR_3-VFR_5
VFR_3-VFR_6
VFR_3-VFR_7
VFR_3-VFR_8
VFR_4-VFR_5
VFR_4-VFR_6
VFR_4-VFR_7
VFR_4-VFR_8
VFR_5-VFR_6
VFR_5-VFR_7
VFR_5-VFR_8
VFR_6-VFR_7
VFR_6-VFR_8
0.0
0.2
0.4
0.6
0.8
1.0
VFR_7-VFR_8
Pai Combina ion
Ve ex- o-Ve ex
Dis ance (mm)
VFR_1-VFR_2
VFR_1-VFR_3
VFR_1-VFR_4
VFR_1-VFR_5
VFR_1-VFR_6
VFR_1-VFR_7
VFR_1-VFR_8
VFR_2-VFR_3
VFR_2-VFR_4
VFR_2-VFR_5
VFR_2-VFR_6
VFR_2-VFR_7
VFR_2-VFR_8
VFR_3-VFR_4
VFR_3-VFR_5
VFR_3-VFR_6
VFR_3-VFR_7
VFR_3-VFR_8
VFR_4-VFR_5
VFR_4-VFR_6
VFR_4-VFR_7
VFR_4-VFR_8
VFR_5-VFR_6
VFR_5-VFR_7
VFR_5-VFR_8
VFR_6-VFR_7
VFR_6-VFR_8
0.0
1.0
2.0
3.0
VFR_7-VFR_8
Figu e 8. Box plo s o e ex- o- e ex dis ances ob ained in each dis ance map wi hin each g oup. A, PHS g oup. B, 3DSC-T g oup. C, 3DSC-S g oup.
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Amezua e al THE JOURNAL OF PROSTHETIC DENTISTRY
labo a o y, i is o be expec ed ha he abili y o he VF
eco d echnique wi h PHS, 3DSC-T, and 3DSC-S acial
scanning me hods o p o ide epea able loca ions o a
maxilla y digi al scan wi h espec o a 3D ace scan
would be wo se in clinical p ac ice.
Al hough he epea abili y o he VF eco d echnique
was ound o be g ea e wi h he PHS acial scanning
me hod han wi h he 3DSC-T and 3DSC-S acial scan-
ning me hods, he 3DSC-T and 3DSC-S me hods p e-
sen se e al ad an ages o e he PHS me hod. These
ad an ages include being less expensi e and easie o
use, hus lowe ing he ba ie o en y o den al clinics o
ob ain 3D ace scans, no equi ing he p ojec ion o a
isible ligh pa e n on he pa ien ’s ace and he e o e
no dis u bing he pa ien , and equi ing hal he scan-
ning ime, he eby educing he need o pa ien
compliance.
26-28
The e o e, u he s udies a e needed o
imp o e he epea abili y o he VF eco d echnique wi h
3DSC-T and 3DSC-S acial scanning me hods.
Limi a ions o his s udy included no being able o
assess he ueness o he VF eco d echnique. This was
because he eal loca ion o a maxilla y digi al scan wi h
espec o a 3D ace scan is unknown in an in i o s udy.
In a p e ious s udy,
17
his loca ion was es ima ed by
aligning he maxilla y digi al scan fi s o a 3D digi al
eplica o he c anio acial ha d issues and hen o a 3D
ace scan, bu his loca ion can be a ec ed by a ious
e o s. Fu he s udies a e needed o de e mine a me h-
odology o assess he ueness o a VF eco d echnique
in an in i o s udy.
CONCLUSIONS
Based on he findings o his in i o s udy, he ollowing
conclusions we e d awn:
1. The acial scanning me hod had a g ea impac on
he epea abili y o he VF eco d echnique.
2. The epea abili y o he VF eco d echnique was
s a is ically significan ly g ea e wi h he PHS acial
scanning me hod han wi h he 3DSC-T and 3DSC-
S acial scanning me hods and wi h he 3DSC-T
acial scanning me hod han wi h he 3DSC-S acial
scanning me hod, indica ing ha he VF eco d
echnique was mo e epea able wi h mo e accu a e
acial scanning me hods.
REFERENCES
1. Alghazzawi TF. Ad ancemen s in CAD/CAM echnology: op ions o p ac-
ical implemen a ion. J P os hodon Res 2016;60:72-84.
2. Lepidi L, Galli M, Mas angelo F, Venezia P, Joda T, Wang HL, e al. Vi ual
a icula o s and i ual moun ing p ocedu es: whe e do we s and?
J P os hodon 2021;30:24-35.
3. Solabe ie a E, Mínguez R, Ba ene xea L, E xaniz O. Di ec ans e o he
posi ion o digi ized cas s o a i ual a icula o . J P os he Den 2013;109:
411-4.
4. Solabe ie a E, O egi JR, Mínguez R, E xaniz O. Imp o ed digi al ans e o
he maxilla y cas o a i ual a icula o . J P os he Den 2014;112:921-4.
Mean Ve ex- o-Ve ex Dis ance (mm)
G oup
0.5
1.0
1.5
2.0
0.0
PHS 3DSC-T 3DSC-S
Figu e 9. Box plo o mean e ex- o- e ex dis ances o dis ance maps ob ained in each g oup.
Table 1. Desc ip i e s a is ics o mean e ex- o- e ex dis ances o
dis ance maps ob ained in each g oup
G oup Mean ±SD (Repea abili y)
95% CI
Lowe Bound Uppe Bound
PHS 0.243 ±0.094 0.206 0.279
3DSC-T 0.437 ±0.171 0.371 0.504
3DSC-S 1.023 ±0.399 0.868 1.178
CI, confidence in e al; SD, s anda d de ia ion.
Table 2. Resul s o be ween-g oup compa isons o mean e ex- o-
e ex dis ances wi h Games-Howell pos hoc es
G oups PCohen d
PHS - 3DSC-T <.001 1.413
3DSC-T - 3DSC-S <.001 1.908
PHS - 3DSC-S <.001 2.692
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