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Sa e zones o he maxilla y al eola
bone in Down synd ome o
o hodon ic minisc ew placemen
assessed wi h cone-beam
compu ed omog aphy
Jacobo Lime es posse, Ma ía e esa Abelei a pazos, Ma ía e nández casado,
Me cedes ou umu o Rial, ped o Diz Dios & Má cio Diniz- ei as
he aim o his s udy was o quan i y he a ailable maxilla y al eola bone in a g oup o indi iduals
wi h Down synd ome (DS) o de e mine he bes a eas o o hodon ic minisc ew placemen . he s udy
g oup consis ed o 40 pa ien s wi h DS aged 12–30 yea s. We also selec ed an age and sex-ma ched
con ol g oup. All measu emen s we e pe o med on c oss-sec ional images ob ained wi h cone-beam
compu ed omog aphy. The selec ed a eas o in e es we e he 4 in e adicula spaces be ween he
dis al wall o he canine and he mesial wall o he second mola , in bo h maxilla y quad an s. We
measu ed he es ibula -pala ine (VP) and mesiodis al (MD) dimensions o dep hs o 3, 6 and 9 mm
om he al eola idge. We also measu ed he bone densi y in he same in e adicula spaces o in e es
o 6 mm o dep h om he al eola c es . VP measu emen s we e longe in he mo e pos e io sec o s
and as he dis ance om he al eola idge inc eased. MD measu emen s also inc eased p og essi ely
as he dis ance om he al eola idge inc eased. in gene al, bo h he Vp and MD measu emen s in
he DS g oup we e simila among he male and emale pa icipan s. As age inc eased, he MD dis ance
inc eased, while he Vp dis ance dec eased. he Vp dis ance was ≥6 mm in a leas 75% o he DS g oup
in p ac ically all assessed in e den al spaces. he MD dis ance was ≥2 mm in a leas 75% o he DS
g oup only be ween he i s and second mola , o 9 mm o dep h om he al eola idge. The sa e a ea
o inse ing o hodon ic minisc ews in DS pa ien s is es ic ed o he mos pos e io and deepes a ea
o he maxilla y al eola bone.
Down synd ome (DS), also known as isomy 21, was i s desc ibed in 1866 by John Langdon Down and ep e-
sen s he mos common li e-bo n human aneuploidy. DS is associa ed wi h men al disabili y and has a cha ac e -
is ic pheno ype in which o o acial abno mali ies a e common1.
I is es ima ed ha mo e han 80% o indi iduals wi h DS ha e se e e o highly se e e den al malocclu-
sions2. The demand o o hodon ic ea men by his g oup has g own p og essi ely2, al hough in many cases i s
app oach can p esen a conside able challenge o he den al eam3.
Technological ad ances, such as o hodon ic empo a y ancho age de ices (TAD) ha minimize he need
o compliance o he success o den al mo emen echniques, can acili a e ea men in pa ien s wi h special
needs4. I has been sugges ed ha pala ine implan s and minipla es ha e compa able o highe success a es han
hose achie ed wi h minisc ews5. Howe e , a ecen ly published ex ensi e e iew ha analyzed 3250 minisc ews
om 41 s udies concluded ha hese p o ide a s able ancho o a ious den al mo emen s and ha i s ailu e a e
is accep ably low (13.5%)6. In he gene al popula ion, minisc ews ha e been employed success ully o co ec ing
skele al abno mali ies such as an e io open bi e7, a equen malocclusion in DS.
The ad an ages o minisc ews include hei small size (which enables placemen in nume ous in ao al a eas,
including he in e adicula spaces), low cos and he ac ha bo h hei inse ion and wi hd awal a e simple
Medical-Su gical Den is y Resea ch G oup (OMEQUI), Heal h Resea ch Ins i u e o San iago de Compos ela (IDIS),
Uni e si y o San iago de Compos ela (USC), San iago de Compos ela, Spain. Co espondence and eques s o
ma e ials should be add essed o M.D.-F. (email: [email p o ec ed])
Recei ed: 11 Janua y 2019
Accep ed: 21 Augus 2019
Published: xx xx xxxx
open
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p ocedu es8. Addi ionally, hei placemen causes minimal auma, and o hodon ic ac ion o ce can be applied
immedia ely o ea ly compa ed wi h den al implan s9.
In DS, minisc ews can be especially indica ed because hey educe he deg ee o coope a ion needed om he
pa ien o achie e oo h mo emen and help sol e he p oblem o c own size and pe iodon ally a ec ed ee h.
When planning he inse ion o minisc ews, i is essen ial o conside ce ain ana omical ac o s such as he p ox-
imi y be ween he oo h oo s, he a ailable a ached gingi a, he ne e s uc u e opog aphy, he maxilla y sinus
mo phology and he co ical bone hickness10. The peculia i ies o many o hese ana omical s uc u es ha e no
ye been analyzed in indi iduals wi h DS. In he gene al popula ion, he highes success a es o he minisc ews
co espond o hose placed in he midpala al line, while he loca ion wi h he poo es p ognosis is he zygoma ic
bu ess11. Al e na i e loca ions ha e been sough o inse ing he minisc ews, such as he in e adicula spaces
be ween he uppe mola s8; howe e , he bone a ailabili y in his a ea in pa ien s wi h DS is unknown. The aim
o his s udy was o assess (in a g oup o indi iduals wi h DS) he opog aphical cha ac e is ics and bone densi y
o he maxilla y al eola p ocess in he loca ions whe e inse ion o o hodon ic minisc ews is mos equen ly
ecommended.
Ma e ial and Me hods
The s udy g oup (DS g oup) consis ed o 40 whi e pa ien s, selec ed acco ding o he ollowing inclusion c i e ia:
age be ween 12 and 30 yea s; gene ically con i med diagnosis o DS; de ini i ely e up ed ee h; a ailabili y o
h ee-dimensional cone-beam compu ed omog aphy (CBCT) images o accep able quali y o he maxilla; no
his o y o su gical p ocedu es in he maxillo acial a ea (wi h he excep ion o s ic ly den al p ocedu es); and no
p e ious o hodon ic/o hopedic ea men o se e e maxilla y auma.
The con ol g oup included 40 nonsynd omic indi iduals ma ched o age and sex. In addi ion o he selec ion
c i e ia applied o he s udy g oup, we excluded hose indi iduals wi h sys emic disease ha could a ec o o acial
de elopmen o den al/skele al ma u i y di ec ly o as a esul o hei ea men .
All images used in his s udy we e om indi iduals wi h DS who had unde gone uppe and lowe jaw CBCT
in a p e ious s udy o e alua e a lan oaxial ins abili y. The con ol g oup unde wen CBCT mainly o he p e-
su gical assessmen o une up ed hi d mola s, he oo eso p ion assessmen o pe iapical lesions, he assess-
men o empo omandibula (TMJ) diso de s and c oss-sec ional imaging p io o den al implan placemen . All
images om he DS and con ol g oups we e e ie ed om he a chi e o he Radiology Uni o he Facul y o
Medicine and Den is y a he Uni e si y o San iago de Compos ela in Spain. All pa icipan s o , as applicable,
hei legal gua dians signed an in o med consen o au ho ize he use o images o eaching o esea ch pu poses.
These adiological s udies we e pe o med in acco dance wi h he adia ion p o ec ion p inciples o “As Low As
Reasonably Achie able (ALARA)” and ollowing he guidelines o he SEDENTEXCT Guideline De elopmen
Panel, Radia ion P o ec ion No. 172: Cone Beam CT o Den al and Maxillo acial Radiology, E idence Based
Guidelines 2012 (www.seden exc .eu). The s udy was app o ed by he e hics commi ee o he Uni e si y o
San iago de Compos ela.
All images employed in he s udy we e ob ained usnig an I-CAT® scanne (Imaging Sciences In e na ional,
Ha ield, PA). The p o ocol o acqui ing and manipula ing he images has been p e iously desc ibed in de ail12.
All measu emen s we e pe o med using open-sou ce Osi iX image p ocessing so wa e (Pixmeo, Gene a,
Swi ze land; www.osi ix- iewe .com).
To pe o m he measu emen s in he es ibula -pala ine (VP) di ec ion based on he axial slices o he o iginal
CBCT images, we pe o med a pano amic econs uc ion o he supe io maxilla using he Den al3DPlugin®
plugin. Using his pano amic econs uc ion, we selec ed he a eas o in e es in bo h quad an s o he supe-
io maxilla, which we e he in e adicula spaces om he dis al wall o he canine o he mesial o he second
Figu e 1. Measu emen based on he c oss-sec ional cone-beam compu ed omog aphy images o he a ailable
maxilla y al eola bone a 3, 6 and 9 mm o dep h om he al eola idge. (a) Ves ibula -pala ine dimension. (b)
Mesiodis al dimension.
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mola . To associa e da a wi h a speci ic oo h, we employed he Wo ld Heal h O ganiza ion’s wo-digi no a ion
sys em (also known as ISO 3950 no a ion)13. F om each a ea o in e es , we ob ained an image o a 1-mm hick
c oss-sec ion wi h which we measu ed he dis ance be ween he ex e nal su aces o he es ibula and pala al
co ical bones o he supe io maxilla, o dep hs o 3, 6 and 9 mm om he al eola idge (Fig.1). We pe o med
a o al o 24 VP measu emen s pe pa ien .
To pe o m he measu emen s in he mesiodis al (MD) di ec ion, we used he same pano amic econs uc ion
o he supe io maxilla desc ibed in he p e ious pa ag aph. Using his image, we selec ed he a eas o in e es and
de e mined hei in e adicula dis ance o dep hs o 3, 6 and 9 mm om he al eola idge (Fig.1), un il a o al
o 24 MD measu emen s pe pa ien had been comple ed.
In he e en o missing ee h in he a ea o in e es , we skipped he measu emen s in he co esponding in e -
adicula spaces. In he e en o pneuma iza ion o he maxilla y sinus wi h in asion o he in e adicula space,
he VP measu emen was pe o med om he es ibula co ical bone o he supe io maxilla o he es ibula
wall o he sinus. When he den al oo s ha delimi ed an a ea o in e es we e sho e han 9 mm, we assigned he
alue o he maximum MD dis ance ob ained in his a ea o in e es o he in e adicula dis ance co esponding
o his dep h om he al eola idge.
Once he VP and MD measu emen s had been pe o med, we delimi ed he ideal a eas o he inse ion o
o hodon ic minisc ews. To his end and based on he s udy by Ma inelli e al.14, which ecommended minis-
c ews wi h a diame e o 1.5–2.3 mm and a leng h o 6–8 mm, we es ablished a minimum e e ence leng h o
6 mm in he VP di ec ion and 2 mm in he MD di ec ion. In each loca ion, we de ined 3 ypes o a eas depending
on he pe cen age o indi iduals who sa is ied he c i e ia o minimum dimensions es ablished as he e e ence:
“sa e y a ea”, i a leas 75% o he indi iduals me he c i e ia; “seconda y a ea”, when he pe cen age was be ween
51% and 74%; and “ isk a ea”, when he pe cen age did no exceed 50%.
To de e mine he bone densi y, we simula ed he placemen o a minisc ew in each o he in e adicula loca-
ions o in e es . To his end, we d ew a ec angle (6 mm long by 1.5 mm wide) a a dep h o 6 mm om he bone
c es on he c oss-sec ions o he supe io maxilla ob ained om he o iginal CBCT images.
The s a is ical analysis was pe o med wi h he ee R so wa e ( e sion 2.12.0, R Co e Team, Vienna,
Aus ia). The al eola measu emen s MD and VP we e eco ded in millime e s and he densi y measu emen s
we e eco ded using g ayscale alues. To e alua e in aobse e eliabili y, we andomly selec ed images om
10 pa icipan s (5 om he DS g oup and 5 om he con ol g oup) and a single ained obse e pe o med all
MEASUREMENT AREA
VP DIMENSION (mm)
Down synd ome Con ol g oup
p alue
In e den al
space Dis ance o
bone c es nMean ± SD Range nMean ± SD Range
13–14
3 mm
30
8.1 ± 1.6 5.0–14.2
33
8.2 ± 1.5 5.4–13.1 0.534
6 mm 8.8 ± 1.8 5.3–15.5 8.7 ± 1.7 5.2–13.4 0.893
9 mm 9.5 ± 2.2 4.9–17.1 9.0 ± 2.2 9.0–15.6 0.482
14–15
3 mm
32
8.7 ± 1.1 5.8–11.4
35
9.4 ± 1.2 7.0–13.1 0.010
6 mm 9.0 ± 1.0 5.6–10.9 10.9 ± 1.4 6.5–13.4 0.455
9 mm 9.4 ± 1.6 5.5–12.2 9.4 ± 1.9 4.0–14.0 0.745
15–16
3 mm
35
10.3 ± 1.3 7.1–12.5
39
11.1 ± 1.5 7.3–14.6 0.022
6 mm 11.0 ± 1.8 6.0–13.8 11.2 ± 2.9 1.8–16.7 0.293
9 mm 11.9 ± 2.1 6.0–14.8 10.4 ± 4.4 1.0–16.6 0.242
16–17
3 mm
39
11.5 ± 1.4 8.5–15.5
29
13.4 ± 1.1 11.2–16.1 0.000
6 mm 11.9 ± 1.5 9.3–16.0 13.1 ± 3.2 0.9–17.3 0.000
9 mm 10.6 ± 4.3 1.3–17.7 11.4 ± 5.7 0.7–18.2 0.050
23–24
3 mm
31
7.9 ± 1.5 5.1–12.1
33
8.3 ± 1.6 4.2–13.2 0.333
6 mm 8.6 ± 1.7 5.6–13.7 8.6 ± 1.8 4.7–13.8 0.941
9 mm 9.2 ± 2.0 5.9–15.3 9.0 ± 1.9 5.7–14.2 0.736
24–24
3 mm
32
8.8 ± 1.3 6.3–11.0
36
9.2 ± 1.2 6.4–12.5 0.512
6 mm 9.1 ± 1.5 5.9–12.1 9.3 ± 1.3 6.2–13.1 0.912
9 mm 11.0 ± 3.6 6.1–13.0 9.6 ± 1.4 7.2–13.5 0.661
25–26
3 mm
36
10.0 ± 1.5 6.7–13.1
38
11.2 ± 1.6 4.6–13.8 0.000
6 mm 10.7 ± 1.7 7.3–14.3 11.6 ± 2.3 2.3–14.7 0.011
9 mm 11.0 ± 3.6 1.3–16.2 10.5 ± 4.6 1.0–15.7 0.723
26–27
3 mm
38
11.8 ± 1.3 8.9–15.6
39
13.2 ± 1.3 9.9–15.9 0.000
6 mm 11.9 ± 1.6 8.7–15.4 13.0 ± 3.5 1.5–16.8 0.000
9 mm 11.0 ± 4.2 1.0–17.5 11.9 ± 5.5 1.1–19.7 0.014
Table 1. Ves ibula -pala ine (VP) dimensions a 3, 6 and 9 mm o dep h om he bone c es in he Down
Synd ome g oup and con ol g oup. VP, es ibula -pala ine; n, numbe o pa icipan s; SD, s anda d
de ia ion;13, maxilla y igh canine; 14, maxilla y igh i s p emola ; 15, maxilla y igh second p emola ; 16,
maxilla y igh i s mola ; 17, maxilla y igh second mola ; 23, maxilla y le canine; 24, maxilla y le i s
p emola ; 25, maxilla y le second p emola ; 26, maxilla y le i s mola ; 27, maxilla y le second mola .
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measu emen s du ing he s udy on 2 occasions wi h a 6-week in e al. The ep oducibili y was e alua ed using
he in aclass co ela ion coe icien (ICC, 0.94; 95% con idence in e al, 0.82–0.99). The signi icance o he di -
e ences be ween 2 si es wi hin a single g oup (DS o con ol) was e alua ed by pe o ming mul iple compa isons
in a linea mixed model. We employed logis ic eg ession o compa e he alues ob ained om each si e be ween
he DS and con ol g oups. Some o he a iables did no ollow a no mal dis ibu ion. The e o e, o analyze he
di e ences in he al eola measu emen s e alua ed acco ding o sex in he DS and con ol g oups, we employed
he Wilcoxon es o independen samples. To analyze he di e ences in he measu emen s e alua ed acco ding
o age, we calcula ed Spea man’s co ela ion coe icien . A p- alue < 0.05 was conside ed s a is ically signi ican .
e hical app o al. The s udy was app o ed by he Ins i u ional Re iew Boa d o he Uni e si y o San iago de
Compos ela (USC), Spain.
in o med consen . No speci ic in o med consen was equi ed as all pa icipan s o , as app op ia e, hei
legal ep esen a i es had signed an in o med consen o au ho ize he use o images o eaching o esea ch
pu poses.
Resul s
The DS g oup had a mean age o 17.8 ± 4.0 yea s, 15 we e emale, and 25 we e male. The mean age o he con ol
g oup was 17.5 ± 5.5 yea s and ollowed he same sex dis ibu ion.
The la ges numbe o missing ee h in he DS g oup was de ec ed in he an e io sec o and mainly co e-
sponded o he canines and igh i s p emola s. Fo his eason, measu emen s o 10 pa ien s could no be
pe o med in his a ea.
Measu emen s o he al eola bone in he Down synd ome and con ol g oups. The VP dis ance
inc eased p og essi ely (bo h in he DS and con ol g oups) he u he back he measu emen s we e aken. In
he DS g oup, he VP dis ance inc eased as he dep h om he bone c es inc eased. In he con ol g oup, his en-
dency was no obse ed, and he opposi e e ec was obse ed in he in e mola spaces. The VP dis ance be ween
he i s and second mola was signi ican ly sho e in he DS g oup han in he con ol g oup (Table1).
MEASUREMENT AREA
MD DIMENSION (mm)
Down synd ome Con ol g oup
p alue
In e den al
space Dis ance o
bone c es nMean ± SD Range nMean ± SD Range
13–14
3 mm
30
2.5 ± 1.4 1.2–7.0
33
2.9 ± 1.4 0.8–7.0 0.037
6 mm 2.3 ± 0.9 0.6–4.6 3.0 ± 1.2 0.7–5.3 0.022
9 mm 4.3 ± 2.3 0.4–7.0 3.9 ± 1.8 1.1–7.3 0.591
14–15
3 mm
32
2.7 ± 1.2 0.5–5.3
35
2.5 ± 0.8 1.0–4.3 0.674
6 mm 2.9 ± 1.3 0.7–6.5 2.8 ± 1.0 0.9–5.0 0.960
9 mm 4.5 ± 2.3 1.5–7.5 3.5 ± 2.0 0.9–7.5 0.050
15–16
3 mm
35
3.0 ± 1.2 0.8–6.6
39
2.8 ± 1.6 0.9–10.8 0.194
6 mm 2.9 ± 1.6 0.5–8.0 3.1 ± 1.5 0.8–8.3 0.472
9 mm 5.2 ± 3.7 0.7–10.7 4.9 ± 2.7 1.6–10.7 0.646
16–17
3 mm
39
2.1 ± 0.8 0.6–3.9
39
2.0 ± 0.9 0.7–4.1 0.465
6 mm 2.6 ± 1.6 0.4–7.1 2.0 ± 1.6 0.3–7.1 0.043
9 mm 4.7 ± 2.1 0.7–6.7 3.6 ± 2.5 0.2–6.7 0.021
23–24
3 mm
31
2.5 ± 1.0 0.6–4.9
33
2.5 ± 1.1 0.4–4.9 0.910
6 mm 3.3 ± 1.9 1.0–7.8 2.4 ± 0.9 0.6–4.1 0.117
9 mm 5.4 ± 2.6 0.8–7.8 3.4 ± 2.2 0.6–7.8 0.000
24–25
3 mm
32
2.6 ± 0.9 0.8–5.3
36
2.5 ± 1.0 0.6–5.3 0.726
6 mm 2.6 ± 1.0 0.2–4.9 2.8 ± 1.2 0.8–6.0 0.882
9 mm 3.8 ± 1.8 1.1–6.1 2.9 ± 1.4 6.1–6.1 0.050
25–26
3 mm
36
2.8 ± 1.2 0.9–7.1
38
3.1 ± 1.5 1.1–7.1 0.472
6 mm 2.8 ± 1.5 0.4–8.2 3.2 ± 1.8 0.5–8.2 0.343
9 mm 4.8 ± 3.4 0.6–10.3 4.8 ± 2.8 0.5–10.3 0.615
26–27
3 mm
38
2.0 ± 0.9 0.7–4.3
39
1.9 ± 0.9 0.5–4.7 0.764
6 mm 2.4 ± 1.3 0.6–5.7 1.9 ± 1.8 0.3–7.1 0.027
9 mm 4.0 ± 1.6 0.3–5.7 3.0 ± 1.9 0.4–5.7 0.023
Table 2. Mesiodis al (MD) dimensions a 3, 6 and 9 mm o dep h om he bone c es in he Down Synd ome
g oup and con ol g oup. MD, mesiodis al; n, numbe o pa icipan s; SD, s anda d de ia ion; 13, maxilla y
igh canine; 14, maxilla y igh i s p emola ; 15, maxilla y igh second p emola ; 16, maxilla y igh i s
mola ; 17, maxilla y igh second mola ; 23, maxilla y le canine; 24, maxilla y le i s p emola ; 25, maxilla y
le second p emola ; 26, maxilla y le i s mola ; 27, maxilla y le second mola .
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The MD dis ance inc eased p og essi ely (bo h in he DS and con ol g oups) he a he he measu emen s
we e aken om he bone c es . The MD dis ance be ween he i s and second mola measu ed a 6 and 9 mm o
dep h om he bone c es was signi ican ly longe in he DS g oup han in he con ol g oup (Table2).
Measu emen s o he al eola bone in ela ion o sex. In gene al, he VP dis ances we e simila in
he male and emale pa ien s in he DS g oup. In he con ol g oup, he VP dis ances be ween he canine and i s
p emola and be ween he i s and second p emola we e signi ican ly longe in he male pa ien s han in he
emale pa ien s (Table3).
The e we e no s a is ically signi ican di e ences in he MD dis ances be ween he male and emale pa ien s,
ei he in he DS o con ol g oup, excep in speci ic cases (e.g., he MD dis ance a 3 mm o dep h om he bone
c es be ween he second p emola and i s mola was longe in he emale pa ien s han in he male pa ien s o
he DS g oup) (Table4).
Measu emen s o he al eola bone in ela ion o age. In e ms o he VP dis ance, all Spea man co -
ela ions we e nega i e, which implies ha he VP dis ance dec eased as age inc eased. In he DS g oup, his ind-
ing was e i ied in i ually all e alua ed in e den al spaces, while in he con ol g oup, his inding was limi ed o
pos e io sec o s (be ween he second p emola and i s mola and be ween he i s and second mola ) (Table5).
When assessing he MD dis ance, in con as , mos o he Spea man co ela ions we e posi i e, which implies
ha he MD dis ance also inc eased wi h age. This inding was con i med in he DS and con ol g oups, excep in
speci ic cases (e.g., be ween he igh i s and second p emola ) (Table5).
ideal a eas o inse ing o hodon ic minisc ews. Based on he VP measu emen s, all e alua ed in e -
den al spaces can be conside ed “sa e a eas” (in he DS and con ol g oups), excep be ween he canine and igh
i s p emola s in he DS g oup (which is a “seconda y a ea”) (Fig.2).
MEASUREMENT AREA
VP DIMENSION (mm)
Down synd ome Con ol g oup
Male Female
p alue
Male Female
p alue
In e den al
space Dis ance o
bone c es nMean ± SD nMean ± SD nMean ± SD nMean ± SD
13–14
3 mm
19
8.1 ± 1.7
11
7.9 ± 1.4 0.999
22
8.5 ± 1.5
11
7.6 ± 1.4 0.143
6 mm 9.0 ± 1.9 8.4 ± 1.5 0.401 9.2 ± 1.6 7.6 ± 1.5 0.015
9 mm 9.9 ± 2.3 8.7 ± 2.0 0.103 9.6 ± 2.1 7.7 ± 1.8 0.022
14–15
3 mm
18
8.7 ± 0.8
14
8.7 ± 1.5 0.732
22
9.8 ± 1.3
13
8.9 ± 0.9 0.031
6 mm 9.1 ± 1.1 8.8 ± 1.6 0.704 9.7 ± 1.5 8.8 ± 1.2 0.094
9 mm 9.7 ± 1.4 9.0 ± 1.9 0.332 10.0 ± 1.8 8.4 ± 1.9 0.042
15–16
3 mm
20
10.3 ± 1.0
15
10.3 ± 1.7 0.526
25
11.0 ± 1.5
14
11.3 ± 1.7 0.319
6 mm 11.1 ± 1.4 10.9 ± 2.2 0.802 11.7 ± 1.8 10.3 ± 4.1 0.608
9 mm 12.0 ± 2.0 11.7 ± 2.4 0.92 11.1 ± 3.6 9.1 ± 5.4 0.334
16–17
3 mm
24
11.5 ± 1.4
15
11.6 ± 1.4 0.665
26
13.5 ± 1.2
13
13.1 ± 0.9 0.325
6 mm 11.8 ± 1.5 12.1 ± 1.5 0.443 13.5 ± 2.3 12.2 ± 4.4 0.612
9 mm 11.2 ± 3.7 9.7 ± 5.2 0.772 11.5 ± 5.6 11.3 ± 6.1 0.976
23–24
3 mm
20
8.3 ± 1.5
12
7.2 ± 1.1 0.044
21
8.9 ± 1.5
12
7.2 ± 1.2 0.002
6 mm 9.1 ± 1.6 7.8 ± 1.5 0.056 9.5 ± 1.6 7.1 ± 1.1 0.000
9 mm 9.9 ± 2.0 8.1 ± 1.6 0.014 9.7 ± 1.9 7.7 ± 1.4 0.004
24–25
3 mm
19
8.8 ± 1.2
14
8.8 ± 1.5 0.743
22
9.7 ± 1.1
14
8.4 ± 0.9 0.001
6 mm 9.1 ± 1.3 9.0 ± 1.7 0.956 9.9 ± 1.2 8.3 ± 0.9 0.001
9 mm 9.9 ± 1.4 9.3 ± 1.9 0.635 10.1 ± 1.5 8.8 ± 1.0 0.016
25–26
3 mm
21
10.0 ± 1.1
15
10.1 ± 1.9 0.7
25
11.5 ± 1.3
13
10.6 ± 2.1 0.248
6 mm 10.7 ± 1.5 10.7 ± 2.1 0.7 12.0 ± 1.7 10.8 ± 3.1 0.397
9 mm 10.6 ± 3.7 11.4 ± 3.5 0.451 11.5 ± 4.0 8.6 ± 5.3 0.090
26–27
3 mm
23
11.6 ± 1.2
15
11.9 ± 1.5 0.324
26
13.5 ± 1.2
13
12.6 ± 1.3 0.107
6 mm 11.7 ± 1.6 12.1 ± 1.5 0.437 14.0 ± 2.0 11.2 ± 5.0 0.107
9 mm 11.4 ± 3.7 10.2 ± 4.9 0.591 12.4 ± 5.4 11.0 ± 5.7 0.531
Table 3. Ves ibula -pala ine (VP) dimensions a 3, 6 and 9 mm o dep h om he bone c es in he Down
Synd ome g oup and con ol g oup, acco ding o sex. VP, es ibula -pala ine; n, numbe o pa icipan s; SD,
s anda d de ia ion; 13, maxilla y igh canine; 14, maxilla y igh i s p emola ; 15, maxilla y igh second
p emola ; 16, maxilla y igh i s mola ; 17, maxilla y igh second mola ; 23, maxilla y le canine; 24,
maxilla y le i s p emola ; 25, maxilla y le second p emola ; 26, maxilla y le i s mola ; 27, maxilla y le
second mola .
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Based on he MD measu emen s, he only bila e al “sa e a ea” in he DS g oup is be ween he i s and second
mola , a 9 mm o dep h om he bone c es . In he con ol g oup, he only “sa e a ea” was be ween he second
p emola and i s mola , a 3, 6 o 9 mm o dep h om he bone c es (Fig.3).
Bone densi y measu emen in he Down synd ome and con ol g oups. In gene al, he e we e no
signi ican di e ences be ween he pa icipan s wi h DS and he con ol g oup, excep in he in e adicula space
be ween he i s and second uppe igh mola , whe e he bone densi y was signi ican ly lowe in he pa icipan s
wi h DS (Table6).
When s udying he in luence o sex on he bone densi y alues in he s udy g oup, we ound no signi ican
di e ences be ween he male and emale pa ien s, excep in he in e adicula spaces be ween he i s and second
uppe igh p emola and be ween he i s and second uppe igh mola , whe e he bone densi y was signi i-
can ly g ea e in he emale pa ien s han in he male pa ien s (Table7).
In gene al, age did no a ec he bone densi y alues, excep o he in e adicula spaces be ween he second
p emola and he i s uppe igh mola (p = 0.01) and be ween he canine and he i s uppe le p emola
(p = 0.03).
Discussion
A pa icula ly na ow mo phology o he pala e bu wi h an e opos e io dimensions and aul heigh simila o
hose o he gene al popula ion is conside ed a pheno ypic cha ac e is ic o DS15. In speci ic loca ions such as he
midpala al su u e a ea, he pala al bone is also hinne in pa ien s wi h DS han in nonsynd omic con ols pai ed
by age and sex. We can he e o e expec ha he e a e o he mo phome ic cha ac e is ics in he maxilla y a ea
ha a e inhe en o he synd ome, al hough we ha e hus a ound no published s udies o con i m i .
The p esen s udy is no exemp om a numbe o me hodological limi a ions ha should be conside ed
when ex apola ing ou esul s. The pa icipan s’ age ange is much wide han ha o pa icipan s in p e i-
ous s udies ha used a simila me hodology16. All pa icipan s we e whi e; howe e , i has been indica ed ha
MEASUREMENT AREA
MD DIMENSION (mm)
Down synd ome Con ol g oup
Male Female
p alue
Male Female
p alue
In e den al
space Dis ance o
bone c es nMean ± SD nMean ± SD nMean ± SD nMean ± SD
13–14
3 mm
19
2.3 ± 0.8
11
2.8 ± 2.0 0.964
22
2.9 ± 1.6
11
2.9 ± 0.9 0.721
6 mm 2.4 ± 1.0 2.0 ± 0.6 0.238 2.9 ± 1.2 3.0 ± 1.2 0.702
9 mm 4.8 ± 2.4 3.4 ± 2.0 0.133 3.8 ± 1.9 4.1 ± 1.7 0.833
14–15
3 mm
18
2.7 ± 0.8
14
2.7 ± 1.6 0.382
22
2.4 ± 0.7
13
2.6 ± 0.8 0.533
6 mm 3.1 ± 1.2 2.6 ± 1.5 0.193 2.7 ± 1.0 3.0 ± 1.1 0.597
9 mm 4.6 ± 2.2 4.4 ± 2.5 0.642 3.2 ± 1.9 4.0 ± 2.2 0.313
15–16
3 mm
20
2.6 ± 0.8
15
3.5 ± 1.4 0.027
25
2.9 ± 1.8
14
2.6 ± 1.3 0.826
6 mm 2.6 ± 1.3 3.3 ± 1.9 0.182 3.2 ± 1.4 3.0 ± 1.8 0.292
9 mm 4.6 ± 3.4 6.0 ± 4.1 0.458 4.6 ± 2.4 5.3 ± 3.2 0.837
16–17
3 mm
24
2.1 ± 0.7
15
2.1 ± 1.0 0.869
26
2.1 ± 1.0
13
1.7 ± 0.8 0.340
6 mm 2.3 ± 1.1 3.1 ± 2.2 0.565 2.0 ± 1.5 1.9 ± 1.9 0.712
9 mm 4.5 ± 2.0 5.0 ± 2.2 0.512 3.8 ± 2.5 3.2 ± 2.4 0.412
23–24
3 mm
20
2.4 ± 1.1
12
2.6 ± 0.9 0.425
21
2.1 ± 1.1
12
3.1 ± 0.9 0.022
6 mm 3.3 ± 1.7 3.2 ± 2.2 0.349 2.3 ± 1.0 2.7 ± 0.7 0.166
9 mm 5.7 ± 2.6 5.0 ± 2.6 0.441 3.4 ± 2.4 3.3 ± 1.9 0.793
24–25
3 mm
19
2.3 ± 0.7
14
3.0 ± 1.1 0.053
22
2.5 ± 1.0
14
2.6 ± 0.9 0.398
6 mm 2.6 ± 1.0 2.6 ± 1.0 0.785 2.6 ± 1.2 3.0 ± 1.1 0.153
9 mm 3.8 ± 1.7 3.9 ± 1.9 0.985 2.7 ± 1.5 3.2 ± 1.3 0.269
25–26
3 mm
21
2.3 ± 0.9
15
3.4 ± 1.4 0.01 25 3.2 ± 1.7
13
2.8 ± 1.2 0.548
6 mm 2.6 ± 1.7 3.1 ± 1.1 0.133 3.0 ± 1.6 3.5 ± 2.2 0.902
9 mm 4.0 ± 3.4 6.0 ± 3.3 0.026 4.1 ± 2.5 6.1 ± 3.0 0.030
26–27
3 mm
23
1.9 ± 0.9
15
2.1 ± 1.0 0.742
26
2.0 ± 1.0
13
1.8 ± 0.7 0.905
6 mm 2.3 ± 1.2 2.5 ± 1.4 0.79 2.0 ± 1.5 1.9 ± 2.3 0.185
9 mm 4.1 ± 1.5 4.0 ± 1.9 0.999 3.1 ± 2.0 2.8 ± 1.9 0.558
Table 4. Mesiodis al (MD) dimensions a 3, 6 and 9 mm o dep h om he bone c es in he Down Synd ome
g oup and con ol g oup, acco ding o sex. MD, mesiodis al; n, numbe o pa icipan s; SD, s anda d de ia ion;
13, maxilla y igh canine; 14, maxilla y igh i s p emola ; 15, maxilla y igh second p emola ; 16, maxilla y
igh i s mola ; 17, maxilla y igh second mola ; 23, maxilla y le canine; 24, maxilla y le i s p emola ; 25,
maxilla y le second p emola ; 26, maxilla y le i s mola ; 27, maxilla y le second mola .
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acial mo phome y is de e mined by e hnici y and ace17. In any case, he diame e and leng h o he minisc ew
implan s does no ensu e he success o he p ocedu e18.
In he DS g oup, he longes VP dis ances we e de ec ed in he in e mola a ea, which allows o he inse ion
o longe minisc ews in his a ea. I has been shown ha , in he gene al popula ion, he hickes pa o he bone
in he buccopala al dimension in he maxilla y a ch is also be ween he i s and second mola s8. The a ailable
bone in he in e mola a ea was hinne in he DS g oup han in he con ol g oup, a esul ha could be explained
by he ac ha he ha d pala e is na owe in he DS g oup han in he con ol g oup19.
The diame e o he selec ed minisc ew will be de e mined by he MD leng h o a ailable bone. I has been
sugges ed ha skele al ancho ing o he minisc ews is s able when hey ha e a diame e be ween 1.5 and 2.3 mm7.
The MD dis ance is highly ele an , gi en ha one o he g ea es isks o minisc ew ailu e is i s p oximi y o he
ee h oo s20. In he DS g oup, he in e mola a ea p esen ed a longe MD dis ance, and he amoun o a ailable
MD bone was g ea e han in he con ol g oup, p obably because he ee h o he DS g oup we e smalle han
hose o he con ol g oup. Mic odon ia is no uncommon among pa ien s wi h DS and can esul in spacing21. In
he gene al popula ion, he in e mola a ea is also conside ed one o he mos eachable loca ions o minisc ew
placemen because i has a la ge space be ween he oo h oo s20. A numbe o au ho s ha e indica ed ha he
longes MD dis ance in he maxilla is on he pala al side be ween he second p emola and i s mola 8.
In he DS g oup, we ound no signi ican di e ences in leng h o he maxilla y al eola bone be ween he
male and emale pa ien s. This inding is consis en wi h ou p e ious esul s in DS in which sex did no a ec
he mo phome y o he ha d pala e15 o he pala al bone hickness12. In con as , a numbe o measu emen s in
he canine and p emola a eas we e la ge in he male pa ien s han in he emale pa ien s in he con ol g oup,
con i ming he sexual dimo phism de ec ed in he gene al popula ion in mos c anio acial measu emen s om
childhood22, in he dimensions o he ha d pala e15 and in he co ical bone hickness in he maxilla y pos e io
egion23.
We obse ed a signi ican educ ion in he VP dis ance wi h age in bo h he DS and con ol g oups, which
could be he esul o a sligh dec ease in he den al a ch wid hs epo ed a e he comple e e up ion o pe manen
MEASUREMENT AREA
VP DIMENSION (mm) M-D DIMENSION (mm)
Down
synd ome Con ol g oup Down
synd ome Con ol g oup
In e den al
space Dis ance o
bone c es SCC p alue SCC p alue SCC p alue SCC p alue
13–14
3 mm −0.44 0.006 −0.21 0.799 −0.28 0.000 −0.23 0.000
6 mm −0.42 0.064 −0.16 0.921 0.46 0.000 −0.23 0.000
9 mm −0.24 0.409 −0.09 0.830 0.38 0.001 −0.06 0.000
14–15
3 mm −0.46 0.000 −0.38 0.002 −0.15 0.002 0.2 0.173
6 mm −0.52 0.000 −0.5 0.000 0.32 0.07 0.18 0.094
9 mm −0.35 0.000 −0.5 0.000 0.47 0.001 0.13 0.139
15–16
3 mm −0.47 0.000 −0.54 0.000 −0.1 0.096 0.27 0.012
6 mm −0.52 0.000 −0.72 0.000 0.35 0.012 0.48 0.000
9 mm −0.58 0.000 −0.43 0.000 0.42 0.002 0.42 0.000
16–17
3 mm −0.49 0.000 −0.41 0.000 0.39 0.024 0.42 0.000
6 mm −0.5 0.000 −0.45 0.000 0.22 0.42 0.39 0.000
9 mm −0.46 0.000 −0.49 0.000 0.31 0.009 0.44 0.000
23–24
3 mm −0.39 0.007 −0.03 0.163 −0.29 0.000 −0.27 0.000
6 mm −0.37 0.026 −0.01 0.246 0.14 0.191 0.03 0.040
9 mm −0.39 0.01 −0.1 0.544 0.48 0.000 0.08 0.235
24–25
3 mm −0.68 0.000 −0.15 0.37 −0.15 0.002 −0.3 0.000
6 mm −0.7 0.000 −0.17 0.213 0.45 0.001 −0.18 0.000
9 mm −0.53 0.000 −0.21 0.053 0.44 0.000 0.04 0.114
25–26
3 mm −0.61 0.000 −0.45 0.000 0.04 0.314 0.08 0.421
6 mm −0.62 0.000 −0.52 0.000 0.37 0.006 0.36 0.016
9 mm −0.57 0.000 −0.56 0.000 0.43 0.000 0.26 0.009
26–27
3 mm −0.6 0.000 −0.33 0.000 0.42 0.039 0.35 0.000
6 mm −0.58 0.000 −0.32 0.000 0.41 0.031 0.54 0.000
9 mm −0.49 0.000 −0.6 0.000 0.51 0.005 0.37 0.000
Table 5. Ves ibula -Pala ine (VP) and Mesiodis al (MD) dimensions a 3, 6 and 9 mm o dep h om he
bone c es in he Down Synd ome g oup and con ol g oup, acco ding o age. VP, es ibula -pala ine; SCC,
Spea man’s co ela ion coe icien ; SD, s anda d de ia ion; 13, maxilla y igh canine; 14, maxilla y igh i s
p emola ; 15, maxilla y igh second p emola ; 16, maxilla y igh i s mola ; 17, maxilla y igh second mola ;
23, maxilla y le canine; 24, maxilla y le i s p emola ; 25, maxilla y le second p emola ; 26, maxilla y le
i s mola ; 27, maxilla y le second mola .
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den i ion24. In con as , he a ailable bone in he MD di ec ion inc eased wi h age, p obably due o he signi ican
e ec ha age has on an e opos e io pala al leng h15.
In he DS g oup and based on he MD measu emen s, he “sa e a ea” co esponded o he deepes loca ions o
he in e mola space. In he gene al popula ion, i has been shown ha co ical bone densi y and hickness sig-
ni ican ly inc ease om he co onal o he apical egions o he al eola bone25, and he mos a o able a eas o
minisc ew inse ion in he maxilla ha e been p oposed om he second p emola o he second mola 26.
A numbe o s udies ha e shown educed bone mass in child en and adolescen s wi h DS27. An impo an
ecen ly published se ies ound ha he maximum peak bone mass was eached ea lie han in he gene al popula-
ion bu ha hose le els we e lowe han in he gene al popula ion28. Addi ionally, indi iduals wi h DS ha e a num-
be o isk ac o s ha can p omo e he onse o os eopo osis, such as p ema u e aging, de elopmen al diso de s,
physical inac i i y, limi ed sun exposu e, como bidi ies and d ug consump ion ha can al e bone me abolism. In
Figu e 2. De e mining he ideal a eas o o hodon ic minisc ew placemen based on he es ibula -pala ine
dimension o he a ailable maxilla y al eola bone.
Figu e 3. De e mining he ideal a eas o o hodon ic minisc ew placemen based on he mesiodis al
dimension o he a ailable maxilla y al eola bone.
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his s udy, we de ec ed no signi ican di e ences in he bone densi y o he uppe maxilla be ween he pa icipan s
wi h DS and he con ol g oup. We ha e ound no simila s udies in he li e a u e wi h which o compa e hese
esul s. In any case, i seems ha he main isk ac o o he ailu e o o hodon ic minisc ews is he p oximi y o he
minisc ew o he oo h oo s11, while bone densi y does no appea o ha e a de e minan e ec 29.
When de e mining he bes loca ion o placing minisc ews, pano amic adiog aphs can unde es ima e he
a ailable in e den al bone space30. The accu acy o pe iapical adiog aphs is g ea e han ha o pano amic adi-
og aphs when assessing he leng h o he oo h oo s31 and when de e mining he posi ion o mini-implan s32.
CBCT, is supe io o pe iapical adiog aphs when assessing he p oximi y o he minisc ews o he oo h oo s,
and i s applica ion has inc eased he success o his o hodon ic ancho ing echnique29. In gene al, 2D adi-
og aphs enable an app oxima e assessmen o he minisc ew’s posi ion ela i e o he su ounding s uc u es,
especially when maps o “sa e zones” a e a ailable, such as hose o he p esen s udy. CBCT should be ese ed o
bo de line cases in which he in e adicula dis ance o he quan i y o a ailable bone issue in he VP di ec ion
is unce ain.
In conclusion, “sa e a eas” o inse ion o o hodon ic minisc ews in indi iduals wi h DS a e limi ed, espe-
cially by he MD dis ance o he a ailable maxilla y al eola bone.
Da a A ailabili y
The da ase s gene a ed du ing and/o analyzed du ing he cu en s udy a e a ailable om he co esponding
au ho on easonable eques .
Re e ences
1. Desai, S. S. Down synd ome: a e iew o he li e a u e. O al Med O al Pa hol O al Radiol Endod 84, 279–285 (1997).
2. Abdul Rahim, F. S., Mohamed, A. M., No , M. M. & Saub, R. Malocclusion and o hodon ic ea men need e alua ed among
subjec s wi h Down synd ome using he Den al Aes he ic Index (DAI). Angle O hod 84, 600–606 (2014).
3. Ou umu o, M. e al. Maxilla y expansion he apy in child en wi h Down synd ome. Pedia ic Den is y 32, 499–504 (2010).
MEASUREMENT
AREA
BONE DENSITY (GV)
Down synd ome
n
Con ol g oup
p alueIn e den al space nMean ± SD Range Mean ± SD Range
13–14 30 817.51 ± 285.90 233.76–1481.24 33 654.03 ± 306.97 70.93–1253.80 0.062
14–15 32 545.12 ± 277.74 49.39–1061.48 35 632.90 ± 231.04 241.75–1016.88 0.243
15–16 35 544.01 ± 325.91 16.93–1307.72 37 564.39 ± 261.75 19.58–1017.17 0.817
16–17 38 470.44 ± 210.30 4.86–1217.25 36 683.91 ± 374.03 13.86–1329.44 0.040
23–24 32 764.56 ± 263.62 384.16–1103.35 33 747.46 ± 301.34 37.09–1328.30 0.821
24–24 33 660.45 ± 274.23 255.77–1244.23 36 674.08 ± 318.41 47.48–1262.00 0.879
25–26 36 584.43 ± 274.23 225.01–1278.38 37 673.99 ± 346.56 42.11–1414.94 0.235
26–27 37 492.46 ± 278.79 65.66–1033.24 35 649.19 ± 288.21 128.10–1289.26 0.065
Table 6. Bone densi y a a dep h o 6 mm om he bone c es in he Down Synd ome g oup and in he
con ol g oup. GV, g ey alues; n, numbe o pa icipan s; SD, s anda d de ia ion; 13, maxilla y igh canine;
14, maxilla y igh i s p emola ; 15, maxilla y igh second p emola ; 16, maxilla y igh i s mola ; 17,
maxilla y igh second mola ; 23, maxilla y le canine; 24, maxilla y le i s p emola ; 25, maxilla y le second
p emola ; 26, maxilla y le i s mola ; 27, maxilla y le second mola .
MEASUREMENT
AREA
BONE DENSITY (GV)
Down synd ome Con ol g oup
Male Female
p alue
Male Female
p alueIn e den al space nMean ± SD nMean ± SD nMean ± SD nMean ± SD
13–14 19 802.70 ± 333.25 11 838.24 ± 218.30 0.772 21 617.43 ± 339.80 12 742.91 ± 200.77 0.371
14–15 18 421.54 ± 230.19 14 718.15 ± 252.14 0.013 21 620.09 ± 234.07 14 663.99 ± 238.62 0.683
15–16 20 468.60 ± 286.50 15 649.60 ± 320.08 0.168 24 542.92 ± 292.52 13 616.52 ± 173.12 0.542
16–17 23 335.63 ± 246.87 15 659.18 ± 339.93 0.012 24 580.46 ± 373.51 12 935.16 ± 245.53 0.032
23–24 20 726.19 ± 205.77 12 818.29 ± 215.31 0.308 20 717.13 ± 315.78 13 821.11 ± 270.65 0.456
24–25 19 580.86 ± 183.48 14 771.87 ± 324.53 0.088 21 710.68 ± 293.91 15 585.19 ± 381.16 0.397
25–26 21 541.01 ± 248.21 15 645.23 ± 310.08 0.374 24 658.12 ± 369.17 13 712.54 ± 307.47 0.739
26–27 22 402.04 ± 216.58 15 619.06 ± 316.77 0.062 24 582.90 ± 267.65 11 810.20 ± 291.00 0.082
Table 7. Bone densi y a a dep h o 6 mm om he bone c es in he Down Synd ome g oup and in he con ol
g oup, by sex. GV, g ey alues; n, numbe o pa icipan s; SD, s anda d de ia ion; 13, maxilla y igh canine;
14, maxilla y igh i s p emola ; 15, maxilla y igh second p emola ; 16, maxilla y igh i s mola ; 17,
maxilla y igh second mola ; 23, maxilla y le canine; 24, maxilla y le i s p emola ; 25, maxilla y le second
p emola ; 26, maxilla y le i s mola ; 27, maxilla y le second mola .
