TECHNO BYTES

Midpalatal suture maturation:

Classification method for individual
assessment before rapid maxillary
expansion
Fernanda Angelieri,a Lucia H. S. Cevidanes,b Lorenzo Franchi,c Joa~o R. Gonc¸ alves,d Erika
Benavides,e and James A. McNamara Jrf
S~ao Paulo and Araraquara, Brazil, Ann Arbor, Mich, and Florence, Italy

Introduction: In this study, we present a novel classification method for individual assessment
of midpalatal suture morphology. Methods: Cone-beam computed tomography images from
140 subjects (ages, 5.6-58.4 years) were examined to define the radiographic stages of
midpalatal suture maturation. Five stages of matura- tion of the midpalatal suture were identified
and defined: stage A, straight high-density sutural line, with no or little interdigitation; stage B,
scalloped appearance of the high-density sutural line; stage C, 2 parallel, scalloped, high-
density lines that were close to each other, separated in some areas by small low-density
spaces; stage D, fusion completed in the palatine bone, with no evidence of a suture; and
stage E, fusion anteriorly in the maxilla. Intraexaminer and interexaminer agreements were
evaluated by weighted kappa tests. Results: Stages A and B typically were observed up to 13
years of age, whereas stage C was noted primarily from 11 to 17 years but occasionally in
younger and older age groups. Fusion of the palatine (stage D) and maxillary (stage E) regions
of the midpalatal suture was completed after 11 years only in girls. From 14 to 17 years, 3 of
13 (23%) boys showed fusion only in the palatine bone (stage D). Conclusions: This new
classification method has the potential to avoid the side effects of rapid maxillary expansion
failure or unnecessary surgically assisted rapid maxillary expansion for late adolescents and
young adults. (Am J Orthod Dentofacial Orthop 2013;144:759-69)

Bernardo do Campo 09640-000, S~ao Paulo, Brazil; e-mail,

fernandaang@yahoo.com.br.
Submitted, May 2012; revised and accepted, April
a
2013. 0889-5406/$36.00
Associate professor, Department of Orthodontics, Methodist University
Copyright © 2013 by the American Association of Orthodontists.
of S~ao Paulo, S~ao Paulo, Brazil. http://dx.doi.org/10.1016/j.ajodo.2013.04.022
b
Assistant professor, Department of Orthodontics and Pediatric
Dentistry, University of Michigan, Ann Arbor.
c
Assistant professor, Department of Orthodontics, University of
Florence, Flor- ence, Italy; Thomas M. Graber visiting scholar,
Department of Orthodontics and Pediatric Dentistry, University of
Michigan, Ann Arbor.
d
Professor, Children’s Clinic Department, Araraquara Dental School,
University of
S~ao Paulo State (UNESP), Araraquara, Brazil; visiting scholar,
Department of Or- thodontics and Pediatric Dentistry, School of
Dentistry, University of Michigan, Ann Arbor, MI.
e
Clinical assistant professor, Department of Periodontics and Oral
Medicine, School of Dentistry, University of Michigan, Ann Arbor,
MI.
f
Thomas M. And Doris Graber Endowed Professor of Dentistry,
Department of Orthodontics and Pediatric Dentistry, School of
Dentistry; research professor, Center for Human Growth and
Development, University of Michigan, Ann Arbor. All authors have
completed and submitted the ICMJE Form for Disclosure of
Potential Conflicts of Interest, and none were reported.
Funded in part by Foundation for Research Support of the State of
S~ao Paulo
(FAPESP); support also was made available through the Thomas M.
and Doris Graber Endowed Professorship, the Department of
Orthodontics and Pediatric Dentistry, University of Michigan.
Address correspondence to: Fernanda Angelieri, Methodist University
of S~ao Paulo, Rua do Sacramento, 230 Bairro Rudge Ramos, S~ao
 apid maxillary expansion (RME) has been

R
used in orthodontic practice for the
correction of poste- rior crossbite and
dental crowding1 as well as to
facilitate correction of Angle Class II2 and
Class III3,4 malocclusions, with the overall
objective to widen the maxilla by separating
the midpalatal suture and the
circummaxillary sutural system.5
Since the pioneering work of Angell 6 150
years ago that introduced the concept that
the maxilla can be expanded by opening the
midpalatal suture, the early orthodontic
literature (1860-1930) included controversy as to
whether it was possible to widen the hard palate
at the midpalatal suture. The landmark work of
Haas7 made RME routine in many orthodontic
practices, beginning in the 1960s. However,
details of the morphology and the maturation
of the midpalatal suture have been
investigated only in histologic studies,8-12 an
autopsy microcomputed tomography study,13
an investigation with occlusal radiographs, 14
and an animal study with multislice computed
tomography.15
Understanding individual variability in the
fusion of the midpalatal suture is essential
in identifying prospectively which late
adolescent or young adult pa- tient can have
RME as a less-invasive alternative to
759
760 Angelieri et al

surgically assisted expansion. The midpalatal and young adult patients.

suture has been described as an end-to-end type of
suture16,17 with characteristic changes in its
MATERIAL AND METHODS
morphology during growth.8,9,11-13,15,16 In the
infantile period, Melsen12 reported that the Baseline diagnostic CBCT images acquired for
midpalatal suture is broad and Y-shaped in clinical purposes in 147 subjects were selected
its frontal sections.16,18 initially; however,
The ossification process in the midpalatal suture
starts with bone spicules from suture
margins along with “islands” (ie, masses of
acellular tissue and inconsistently calcified tissue)
in the middle of the sutural gap.8,9,13,16 The
formation of spicules occurs in many places
along the suture, with the number of spicules
increasing with maturation9,19 and forming
many scalloped areas that are close to each
other and separated in some areas by
connective tissue.10,11 Concomitantly,
interdigitation increases11,12; then fusion occurs
earlier in the posterior area of the suture, with
progression of ossification taking place
from posterior to anterior,9,11 with
resorption of cortical bone in the sutural
ends and formation of cancellous bone.16,18
The start and the advance of fusion of the
midpalatal suture vary greatly with age and
sex. Persson and Thilander9 observed fusion of
the midpalatal suture in subjects ranging from
15 to 19 years old. On the other hand, patients at
ages 27, 32,9 54,11 and even 7113 years have been
reported to have no signs of fusion of this
suture. Such findings indicate that variability
in the developmental stages of fusion of the
midpalatal suture is not related directly to
chronologic age, particularly in young adults.8-11,13
For this reason, Revelo and Fishman14 proposed
indi- vidual assessment of the midpalatal suture
morphology with occlusal radiographs before RME
therapy. However, occlusal radiographs are
not reliable for analyzing midpalatal suture
morphology because the vomer and the
structures of the external nose overlay the
midpalatal area and thus might lead to false
radiographic interpre- tations of midpalatal
suture fusion.10
Cone-beam computed tomography (CBCT)
provides 3-dimensional visualization of the oral
and maxillofacial structures at relatively low cost,
no superimposition of adjacent structures, easy
accessibility, and low radiation exposure
compared with multislice medical computed
tomography.20 The aim of this study was to
present a novel classification method for the
individual assess- ment of midpalatal suture
morphology using CBCT im- ages because RME is
an unpredictable treatment for late adolescent

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Angelieri et al 761

classification of the maturational stage of the

Table I. Demographics of the sample for sex midpalatal suture (Fig 1). For subjects with a
and
Sex
age5-\11 y 11-\14 y 14-18 y .18 y Total curved palate, the palate was evaluated in 2
Female 24 24 19 19 86 central cross-sectional axial slices, identifying
Male 4 24 13 13 54 the posterior
Total 28 48 32 32 140

7 subjects were excluded because of poor-quality

scans (eg, blurry images). CBCT scans from 140
subjects (86 female, 54 male; Table I), with
ages from 5.6 to 58.4 years and no history of
previous orthodontic treatment, were examined
to determine the radiographic stages of
midpalatal suture maturation, as described in
this study. All CBCT images were taken before
orthodontic treatment for clinical reasons to aid
in the diagnosis of clinical conditions such as
canine impaction or skeletal malocclusion.
Institutional review board approval for the
study was obtained from the University of
Michigan. The CBCT scans images were
obtained with an iCAT cone-beam 3-
dimensional imaging system (Imaging
Sciences International, Hatfield, Pa). Each
subject was seated in an upright position with
the Frankfort hori- zontal plane (superior aspect
of the external auditory canal to infraorbital rim
line) parallel to the ground during the scanning
process. For all scans, the mini- mum field of
view used was 11 cm, and the scan time
ranged from 8.9 to 20 seconds with a
resolution
of 0.25 to 0.30 mm.
Image analysis was performed using
Invivo5 (Anatomage, San Jose, Calif). The
following steps were executed for determining
and analyzing the matura- tional stages of
the midpalatal suture.
1. Head orientation. Natural head position in
all 3 planes of space was verified or
corrected. The cursor (the position indicator)
of the image analysis soft- ware was
positioned at the patient's midsagittal
plane in both the coronal and axial views
(Fig 1). In the sagittal view, the patient's head
was adjusted so that the anteroposterior
long axis of the palate was horizontal.
2. Standardization of the axial cross-
sectional slice used for sutural assessment.
In the sagittal plane, the midsagittal cross-
sectional slice was used to position the
palate horizontally, parallel to the soft- ware's
horizontal orange line (Fig 1, B). After
placing the horizontal line along the
palate, the central cross-sectional slice in
the superoinferior dimension (ie, from the
nasal to the oral surface) was used for
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762 Angelieri et al

Fig 1. Standardization of head position in the A, axial; B, sagittal, and C, coronal planes
to allow consistent assessments of the midpalatal suture. Note that in B, the sagittal
view, the orange line that indicates the position of the axial plane view is positioned
through the center of the superoinferior dimension of the hard palate (Invivo5).

and anterior regions of the midpalatal suture described in previous histologic

sepa- rately (Fig 2). For subjects with a thicker
palate, the palate was evaluated in the 2
most central axial slices (Fig 3). A curved
palate was defined as a palate where the
anterior and posterior portions cannot be
visualized in the same axial slice, and the
sutural staging classification requires 2 slices.
A thick palate was defined as a palate where
the midpalatal suture can be assessed in more
than 3 axial slices (1 oral, 1 central, and 1
nasal); for this reason, a thick palate might
have 2 or more central slices.
3. Definition of the maturational stages of the
midpa- latal suture. The stages of fusion of
the midpalatal suture were described from
the analysis of these standardized CBCT
cross-sectional images in the axial plane
by an orthodontist (F.A.) and an oral and
maxillofacial radiologist (E.B.). The definition
of each CBCT radiographic appearance
of the sutural maturation stage followed
the findings of unique morphology in the
maturation of the midpa- latal suture

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Angelieri et al 763

studies.8,16,18 The radiographic aspect of

the midpalatal suture from early infancy
was observed as a high-density line or area
even before sutural interdigitation and fusion.
The following descriptive stages of
midpalatal suture maturation are pro-
posed (Fig 4, A and B).

In stage A, the midpalatal suture is almost a

straight high-density sutural line with no or little
interdigitation 12,13,15,16
(Fig 5).
In stage B, the midpalatal suture assumes an
irregular shape and appears as a scalloped
high-density line (Fig 6, A). Patients at stage B
can also have some small areas where 2 parallel,
scalloped, high-density lines close to each other
and separated by small low-density spaces are
seen (Fig 6, B).13,15
In stage C, the midpalatal suture appears as 2
parallel, scalloped, high-density lines that are
close to each other, separated by small low-
density spaces in the maxillary and palatine
bones (between the incisive foramen and the
palatino-maxillary suture and posterior to
the

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764 Angelieri et al

Fig 2. For subjects with a curved palate, 2 axial plane images through the posterior
and anterior regions were used. The central cross-sectional slices along the axis of the
palate in the anterior and posterior regions were evaluated.

Fig 3. For patients with a thick palate, the 2 most central axial slices were analyzed.

palatino-maxillary suture). The suture can be

progressing from posterior to anterior.9,11 In
arranged in either a straight or an irregular pattern
the palatine bone, the midpalatal suture
(Fig 7, A and B). In stage D, the fusion of the
cannot be visualized at this stage, and the
midpalatal suture has occurred in the
parasutural bone density is increased (high-
palatine bone, with maturation
density bone) compared with

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Angelieri et al 765

Fig 4. A, Schematic drawing of the maturation stages observed in the midpalatal

suture. It is a simpli- fication of the sutural morphology and should not be used for
diagnosis. Sutural morphology can vary between stages, and diagnostic criteria are
based on the decision tree in B and the definitions of the 5 stages. B, Decision tree for
classification of the maturation stages of the midpalatal suture.

the density of the maxillary parasutural bone. selected after full

In the maxillary portion of the suture, fusion
has not yet occurred, and the suture still can
be seen as 2 high- density lines separated by
small low-density spaces (Fig 8). In stage E,
fusion of the midpalatal suture has occurred
in the maxilla. The actual suture is not visible in
at least a portion of the maxilla.16,18 The
bone density is the same as in other regions
of the palate
(Fig 9).13
All axial central cross-sectional slices used for
assess- ment of the midpalatal suture were

American Journal of Orthodontics and Dentofacial Orthopedics November 2013 ● Vol 144 ● Issue
766 Angelieri et al

review of all cross-sectional axial slices by the

principal investigator (F.A.). These slices were
arranged in a pre- sentation (Microsoft Office
PowerPoint 2007; Microsoft, Redmond, Wash)
with a black background and codes that were
displayed sequentially on a high-definition
computer monitor. Each image was classified
blindly by the principal investigator in a
darkened room. No change in contrast or
brightness of these images was undertaken.
This evaluation was considered the ground truth.
Consensus among radiographic interpretation
or more reliable interpretation should not be
considered a

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Angelieri et al 767

Fig 5. Stage A of maturation of the midpalatal A weighted kappa coefficient was calculated to
suture is seen in this patient as a relatively eval- uate intraexaminer and interexaminer
straight high-density line at the midline. agreement, as well as the agreement between
the examiners and the
gold standard because a gold standard would
require histologic or microcomputed
tomography examination of specimens. The
term “ground truth” more frequently is used
regarding consensus of radiographic interpreta-
tion or reliable interpretations.
A validation study of the proposed
maturational stages of the midpalatal suture
was performed by
3 experienced orthodontists (F.A., L.H.C., L.F.)
who each had over 1 year of experience in
interpreting CBCT scans for diagnostic
purposes in specific research applications. The
definitions and figures (Figs 5-9) of the
maturational stages of the midpalatal suture
were shown in the Power Point presentation
with a black background. Examiner
calibration was performed using 10 images,
in which all orthodontists openly classified
the midpalatal suture, and any questions
regarding the different maturation stages
were discussed. For the validation study, 30
images were randomly selected to represent all
maturational stages of the midpalatal suture.
The 3 orthodontists classified all images
blindly in the same room under dim light
conditions, using the same high-definition
monitor. A second viewing session and
reclassification by the same orthodontists
was done 2 days later in the same way
after random rearrangement of the same
images.

Statistical analysis

American Journal of Orthodontics and Dentofacial Orthopedics November 2013 ● Vol 144 ● Issue
768 Angelieri et al

Fig 6. A, Stage B is observed as 1 scalloped,

high- density line at the midline. B, Stage B in
another subject is characterized by a scalloped
high-density line in some areas and, in other
areas, as 2 parallel, scalloped, high-density lines
close to each other and separated by small low-
density spaces.

ground truth. The statistical software used was

MedCalc (version 12.3.0; MedCalc Software,
Mariakerke, Belgium). The agreement was
defined according to the scale of Landis and
Koch.21

RESULTS
The intraexaminer and interexaminer
reproducibility values demonstrated
substantial agreement, with

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Angelieri et al 769

Fig 8. Stage D is visualized as 2 scalloped, high-

density lines at the midline on the maxillary
portion of the palate. The midpalatal suture
cannot be visualized in palatine bone, and the
density of the parasutural palatine bone is
higher compared with the parasutural maxillary
bone.

Fig 7. Stage C is visualized as 2 parallel,

scalloped, high- density lines that are close to
each other and separated in some areas by small
low-density spaces. The suture can be arranged
in either A, a straight or B, an irregular pattern.

weighted kappa coefficients from 0.75 (95% Fig 9. At stage E, sutural fusion has occurred in
confidence interval [CI], 0.57-0.93) to 0.79 (95% the maxilla. The midpalatal suture cannot be
CI, 0.60-0.97), and identified, and the parasutural bone density is
the reproducibility of examiners with the ground the same as in other regions of the palate.
truth showed almost perfect agreement, with
weighted kappa coefficients from 0.82 (95% CI, one 13-year-old boy. Stage B was present
0.64-0.99) to 0.93 (95% CI, 0.86-1.00). mainly up to 13 years of age, with 6 of 32
The maturational stages of the midpalatal subjects (23% of boys, 15.7% of girls) from 14
suture observed in the sample are shown in to 18 years of age. Stage C was observed
Table II. Great variability was verified in the mainly from 11 to 18 years of age. Howev- er, two
distribution of the mat- urational stages of the 10-year-old girls (8.3% of girls) and 4 of 32
midpalatal suture regarding chro- nologic age. adults (15.7% of girls, 7.7% of boys) were in
Stage A was noted in the early childhood period stage C. No subject from 5 to almost 11 years
from 5 to almost 11 years of age, except for of age had fusion of the midpalatal suture.

American Journal of Orthodontics and Dentofacial Orthopedics November 2013 ● Vol 144 ● Issue
770 Angelieri et al

Table II. Distribution of the maturational stages of the midpalatal suture

Stage 5-\11 11-\14 14-18 y .18 y Total
y y
Female Male Female Mal Female Male Femal Male
e e
A 3 1 0 1 0 0 0 0 5
B 19 3 12 16 3 3 1 0 57
C 2 0 6 7 5 7 3 1 31
D 0 0 1 0 3 3 7 3 17
E 0 0 5 0 8 0 8 9 30
Total 24 4 24 24 19 13 19 13 140

Fig 10. At the axial cross-sectional slice closer to the oral cavity indicated by the orange
horizontal line in the sagittal view (A), the midpalatal suture may appear to have a low-
density space at the midline (B). However, at the central axial cross-sectional slice
indicated by the orange horizontal line in the sagittal view (C), it can be observed that the
midpalatal suture is fused (D).

From 11 to almost 14 years of age, 6 of 24 girls ulceration or necrosis, and

(25%) had fusion of the midpalatal suture in
palatine (stage D) or maxillary (stage E) bone. For
subjects between 14 and 18 years of age, 11 of
19 girls (57.9%) had fusion of the midpalatal
suture in palatine (stage D) or maxillary
(stage E) bone; only 3 boys (23%) were in
stage D. This variability also was observed in
adults, who most frequently had fusion of the
midpalatal suture (stages D and E), 4 subjects
(12.5%) had no fused suture in stage C, and 1
subject (3.1%) was in stage B.
DISCUSSION
Clinical experience has shown that RME
failure is not rare in adolescent and young
adult patients.1 Serious pain, mucosal
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Angelieri et al 771

accentuated buccal tipping and gingival

recession in the posterior teeth have been
shown to occur after RME failure. 22-26
Although surgical expansion is possible at
any time throughout life, maxillary widening
through multisegment osteotomies has been
reported to be the most unpredictable
procedure among all orthognathic surgery
modalities.27,28 The unpredictability of the
surgical expansion has to do with its relapse
potential. Those findings have motivated
many surgeons to treat transverse
discrepancies in 2 stages with surgically
assisted RME. These study findings could
elucidate the diagnostic stage of sutural
maturation and the indication for surgically
assisted RME that increases morbidity and
treatment costs.

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772 Angelieri et al

Fig 11. A patient whose palate was thinner (superoinferiorly) in the maxillary region, where
the midpa- latal suture was fused earlier.

The treatment choice of whether an overall midpalatal suture morphology using

adolescent or a young adult patient is a CBCT. Histologic and microcomputed
suitable candidate for RME without a surgical tomography analyses are limited to assessments
assist is a relevant clinical question. of small sections of the total anteropos- terior
Chronologic age is unreliable for determining suture length only, even if several serial sections
the developmental status of the suture during
growth, as evidenced by our study inwhich subjects
older than 11 years presented at all stages of
midpalatal sutural maturation (Table II).29-31
Additionally, histologic studies have shown great
variability in the maturation of the midpalatal
suture.8-11,13 For these reasons, the
development of a method for individual
assessment of the maturation of the midpalatal
suture has been deemed essential.
The images in Figures 5 through 11
illustrate the stages of sutural fusion;
however, the diagnosis of sutural maturation
should include a radiographic review of all
palate axial cross-sections for adequate staging.
After review of all slices, the classification of
sutural fusion presented in this study was based
on the most central axial CBCT cross-sectional
slices through the midportion of the trabecular
bone of the hard palate, bordered by the oral
cavity and the floor of the nasal cavity in
which the suture showed the most advanced
signs of maturation. The proposed
classification of sutural fusion involved
radiographic interpretation of the central axial
cross-sectional slice selected from the
midsagittal plane view of the palate for subjects
with either a relatively straight or a curved
palate (Figs 1 and 2). Evaluation of the axial
cross-sectional slice through the cortical bone
closer to the oral cavity might not be reliable (Fig
10).
This investigation is the first to evaluate the
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Angelieri et al 773

from 1 area are available. In histologic studies,8-

12
only frontal sections have been evaluated; this
restricts their clinical application, especially
since midpalatal suture maturation occurs
from the posterior to the anterior region.9,11
Regarding prediction of RME success or failure,
it has been advocated in histology and
microcomputed to- mography studies that the
presence or lack of fusion is not extremely
important, whereas the percentage of fusion in
each subject is more critical.9,11-13 Persson
and Thilander9 have speculated that midpalatal
sutures with a fusion index below 5% could be
expanded using conventional RME orthopedic
forces. Histologic and microcomputed
tomography studies found fusion indexes of
the midpalatal suture below 5% in subjects
from 18 to 38 years,10 14 to 71 years,13 and
18 to 63 years of age.11 However, these
histologic and micro- computed tomography
data do not explain why it is difficult to open
the midpalatal suture clinically with
conventional RME in patients older than 25
years of age. Many studies have advocated that
most of the resis- tance to midpalatal suture
separation in adults is due to fusion of the
circummaxillary sutures.12,13,32-34 The
hypothesis that the stage of sutural maturation
might be related to the success of orthopedic
expansion is a different research question that
was not tested in this study.
An interesting finding concerned stage D,
in which the fusion of the palatine portion of
the midpalatal suture has occurred. Because
maturation of the midpala- tal suture occurs from
the back to the front of the oral cavity, clinical
observations in adult and late adolescent patients
might be related to sutural fusion in the palatine
bone, as verified in this study in which stage D was
pres- ent in girls after 11 years and in boys after
14 years of

American Journal of Orthodontics and Dentofacial Orthopedics November 2013 ● Vol 144 ● Issue
774 Angelieri et al

age.9,11 These findings have great clinical circumpubertal ages (11-18 years).35 The
relevance in that transverse discrepancies are resistance to expansion possibly can be
located mostly in the posterior region. Fusion explained by the greater percentage of subjects in
of the midpalatal suture at stage D would stage C during pu- berty or even early fusion of
prevent sutural opening with RME in the the midpalatal suture (stages D and E) in girls.
molar region, even though the opening of an
anterior diastema could be observed. This
scenario would lead to skeletal transverse
increase in the anterior maxillary region
followed by dental changes only in the
posterior region, where side effects could
include molar or premolar extrusion and
periodontal damage.
In 2 previous histologic investigations, only
frontal sections of the midpalatal suture at the
maxillary bone were analyzed; the palatine
portion of the suture was not evaluated.9,10 In
other studies, even though the palatal
specimens were between the incisive foramen
and the posterior spine of the hard palate, the
investigators did not evaluate variations in
fusion at different areas of the palate.11,13
Many 11- to 18- year-old girls had a thinner
area of the palate in the maxillary bone where
the midpalatal suture was fused; for this reason,
they were classified as stage E (Fig 11).
Persson and Thilander9 conducted the only
histologic study of the posterior maxillary part of
the midpalatal suture that reported a sutural
fusion index of at least 17% in subjects from 15 to
35 years of age. This percent- age of sutural
fusion of the posterior part of the palate was
considered an indicator that a conventional
RME approach would not be a viable
treatment option for those patients.
Based our proposed staging methodology, we
specu- late that at stages A and B a conventional
RME approach would have less resistant forces and
probably more skel- etal effects than at stage C,
when there are many initial ossification areas
along the midpalatal suture. These areas of
initial ossification have been described previ-
ously by Melsen19 as “bony islands”
throughout the midpalatal suture. Initial
diagnosis of stage C might indicate that the
timing of RME is critical because the start of
fusion of the palatine portion of the suture could be
imminent. Patients in stages D and E might be
better treated by surgically assisted RME because
fusion of the midpalatal suture already has
occurred partially or totally, hampering the
RME forces from opening the suture.
Interestingly, our results (Table II) might
help to elucidate clinical findings in which
RME is obtained easily up to 10 years of age,
with more skeletal effects than in later
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Angelieri et al 775

Adults had great variability in sutural 5. McNamara JA Jr. Long-term adaptation to changes in the
maturation, as corroborated by other trans- verse dimension in children and adolescents: an
overview. Am J Orthod Dentofacial Orthop
studies.9,11 We found that 53% of the adults 2006;129(Suppl):S71-4.
were in stage E, 31% were in stage D, 13%
were in stage C, and 1 subject (3%) was in
stage B. For subjects with fusion of the
midpalatal suture only in the palatine bone
(stage D), a clinical attempt of RME probably
would fail in the posterior region despite the
interincisal opening and in the maxillary bone
portion of the suture, leading to failure of the
RME procedure.
The sutural classification system described
and vali- dated in this study has the potential to
allow a reliable clinical method for individual
assessment of midpalatal suture morphology
before RME, mainly for late adoles- cent and
young adult patients in whom this treatment is
unpredictable. Moreover, the system of
maturation staging of the midpalatal suture
described here can be applied to other
circummaxillary sutures. Such assess- ments
can aid our understanding of which patients
would show more dental than orthopedic
effects in RME and provide knowledge of
orthopedic effects or resistance at
circummaxillary sutures.

CONCLUSIONS
The classification of midpalatal sutural fusion
us- ing CBCT allows the diagnosis of the
overall antero- posterior characteristics of
the midpalatal suture, without overlapping
of other anatomic structures. This method
might provide reliable parameters for the
clinical decision between conventional and
surgi- cally assisted RME for adolescent and
young adult pa- tients.

ACKNOWLEDGMENTS

We thank the artist Chris Jung for drawing the

stages of midpalatal suture maturation.

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