Relationship between stomatognathic alterations and idiopathic scoliosis: a systematic review with meta-analysis of observational studies

Abstract

Purpose
The objective of this systematic review was to assess a possible relationship between stomatognathic alterations and idiopathic scoliosis (IS).

Design
This study is a systematic review with meta-analysis of observational studies.

Methods
The protocol of this systematic review with meta-analysis was registered in PROSPERO (CRD42022370593). A bibliographic search was carried out in the Pubmed (MEDLINE), Scopus, Web of Science and CINAHL databases using the MeSH terms ‘Scoliosis’ and ‘Stomatognathic Disease’. The odds ratio (OR) of prevalence and standardized mean difference (SMD) were used to synthesize the results.

Results
Of 1592 studies located, 14 studies were selected with 3018 subjects (age: 13.9 years). IS was related to Angle’s class II (OR = 2.052, 95% CI = 1.236–3.406) and crossbite (OR = 2.234, 95% CI = 1.639–3.045). Patients with malocclusion showed a higher prevalence of IS than controls (OR = 4.633, 95% CI = 1.467–14.628), and subjects with IS showed high overjet (SMD = 0.405, 95% CI = 0.149–0.661) and greater dysfunction due to temporomandibular disorders (SMD = 1.153, 95% CI = 0.780–1.527).

Conclusion
Compared with healthy controls, subjects with IS have twice the risk of suffering from occlusion disorders, present greater temporomandibular dysfunction and have a greater overjet in the incisors. Moreover, subjects with malocclusion have an IS prevalence up to four times higher. The systematic orofacial examination of patients with IS should be recommended.

Full text

vv
8:10 771–780
Relationship between stomatognathic alterations and
idiopathic scoliosis: a systematic review with
meta-analysis of observational studies
Francisca Gámiz-Bermúdez1, AlfonsoJavier Ibáñez-Vera 2,
Esteban Obrero-Gaitán2, Irene Cortés-Pérez2, Noelia Zagalaz-Anula 2 and
Rafael Lomas-Vega2
1Unidad de Gestión Clínica Adra, Distrito Sanitario Poniente de Almería, Avenida Picasso, Adra, Spain
2Department of Health Sciences, University of Jaen, Jaen, Spain
• Purpose: The objective of this systematic review was to assess a possible relationship
between stomatognathic alterations and idiopathic scoliosis (IS).
• Design: This study is a systematic review with meta-analysis of observational studies.
• Methods: The protocol of this systematic review with meta-analysis was registered
in PROSPERO (CRD42022370593). A bibliographic search was carried out in the
Pubmed (MEDLINE), Scopus, Web of Science and CINAHL databases using the MeSH
terms ‘Scoliosis’ and ‘Stomatognathic Disease’. The odds ratio (OR) of prevalence and
standardized mean difference (SMD) were used to synthesize the results.
• Results: Of 1592 studies located, 14 studies were selected with 3018 subjects (age: 13.9
years). IS was related to Angle’s class II (OR = 2.052, 95% CI = 1.236–3.406) and crossbite
(OR = 2.234, 95% CI = 1.639–3.045). Patients with malocclusion showed a higher
prevalence of IS than controls (OR = 4.633, 95% CI = 1.467–14.628), and subjects with IS
showed high overjet (SMD = 0.405, 95% CI = 0.149–0.661) and greater dysfunction due to
temporomandibular disorders (SMD = 1.153, 95% CI = 0.780–1.527).
• Conclusion: Compared with healthy controls, subjects with IS have twice the risk of suffering
from occlusion disorders, present greater temporomandibular dysfunction and have a
greater overjet in the incisors. Moreover, subjects with malocclusion have an IS prevalence
up to four times higher. The systematic orofacial examination of patients with IS should be
recommended.
Introduction
Adolescent idiopathic scoliosis (AIS) is the most prevalent
paediatric orthopaedic malformation, affecting 2–3% of
adolescents (1). This three-dimensional spine deformity
must be at least 10° in the coronal plane as measured
with the Cobb method (2) to full the diagnostic criteria
for IS, with a high risk of development and progression
(3). Despite research efforts, no curative treatment is
currently available, as the understanding of its aetiology
is still challenging. Several hypotheses have been
suggested, such as structural musculoskeletal alterations
specically related to growth and development (4),
genetic transmission (5), vitamin D (6) or melatonin
deciency (7) and vestibular alterations (8, 9). The
wide heterogeneity among these hypotheses suggests
that several disturbances could contribute to this spine
deformity.
One of the lines of research in recent years has
investigated the possible alteration of motor control in
children with IS. It has been suggested that subjects with
spinal deviation could present an alteration in postural
balance measured through the movements of the centre
of body pressure (10), having ruled out that IS could be
due to an isolated alteration of the vestibular system (11).
In postural control regulation, several systems are
involved, such as the visual, vestibular and somatosensory
systems. The stomatognathic system plays an important
role in this last system, as the inputs received from this
system contribute to postural control and balance
response (12). In a review in 2019, Langella et al.
concluded that the available evidence did not clarify
Correspondence
should be addressed
to A J Ibáñez-Vera
Email
ajibanez@ujaen.es
EFORT Open Reviews
(2023) 8, 771–780
-23-0094
8
10
Keywords
fscoliosis
fadolescent idiopathic
scoliosis
ftemporomandibular
joint disorders
fstomatognathic diseases
focclusal dysfunction
fmalocclusion
fmandibular diseases
SPINE
© 2023 the author(s)
www.efortopenreviews.org
https://doi.org/10.1530/EOR-23-0094
This work is licensed under a Creative Commons
Attribution-NonCommercial 4.0 International License.
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 772
the possible relationship between spinal deformity and
malocclusion (13), although it is accepted that altered
perception caused by a temporomandibular disorder
could bias the information received by postural control
centres in the central nervous system through the
trigeminal nerve, causing abnormal postural responses
(14). In this sense, a recent study found that a few
months after orthognathic surgery the orientation of the
head in the frontal plane improves, and that after these
drastic mandibular changes, the weight of proprioceptive
signals linked to the mandibular system can increase to
constitute a new frame of reference to orient the head
in space and improve static postural stabilization (15).
However, to date the reviews focused largely on studies
that analysed the relationship between craniofacial
morphology and the appearance of scoliosis, and the
quantity and homogeneity of the studies did not allow a
statistical integration of the results of the different studies.
Considering stomatognathic alterations as a plausible
aetiology of IS, the aim of this systematic review is to
analyse the existence of a relationship between alterations
in the stomatognathic system and idiopathic scoliosis.
Materials and methods
Review design
This systematic review with meta-analysis was conducted
in accordance with the recommendations of the Meta-
Analysis of Observational Studies in Epidemiology
(MOOSE) Group guidelines (16), the Preferred Reporting
Items for Systematic Reviews and Meta-Analyses
(PRISMA) statement (17) and the Cochrane Handbook for
Systematic Reviews of Interventions (18). The protocol of
this review was previously registered in PROSPERO (code
CRD42022370593).
Literature search and bibliographical sources
Two authors (ICP and AJIV) independently performed
a literature search up to October 2022 in the PubMed
(MEDLINE), SCOPUS, Web of Science (WOS) and
CINAHL Complete databases. The database searches
were accompanied by additional searches of other
sources, such as previously published articles, abstracts
and conference proceedings, expert articles and grey
literature. For the search strategy, we identied two
search domains: scoliosis and stomatognathic diseases.
In accordance with the Medical Subject Headings (MeSH)
for MEDLINE, the key words employed were ‘scoliosis’,
‘temporomandibular joint disorders’ and ‘stomatognathic
diseases’. In addition, our search strategy included
synonyms and input terms related to the key words, such
as ‘idiopathic scoliosis’, ‘adolescent idiopathic scoliosis’,
‘crossbite’, ‘malocclusion’ or ‘occlusal dysfunction’. The
Boolean operator ‘AND’ was used to join conditions, and
‘OR’ was used to combine synonyms within the search
strategy. Filters related to language, publication date and
free full-text access were not set. A third expert author
(RLV) revised the bibliographic search and resolved
doubts. Table 1 shows the search strategy used in each
database.
Study selection: inclusion and exclusion criteria
Two blinded reviewers (ICP and FGP) independently
screened the titles and abstracts of all references retrieved
in each database and any additional sources. When one
of the authors identied an article with the potential
for inclusion in the qualitative synthesis, this article was
examined in detail by two authors. All disagreements
were resolved by a third author (RLV).
A study was included in the present systematic review
when it met all of the following inclusion criteria: (i)
observational studies, such as cross-sectional, cohort,
and case–control studies; (ii) sample composed of
patients with scoliosis; (iii) comparison with healthy
subjects; (iv) analysis of the morphology or function of
the stomatognathic apparatus before any therapy and (v)
studies analysing the prevalence of scoliosis in patients
with malocclusion in comparison with patients without
malocclusion. The exclusion criteria were as follows: (i)
studies carried out in animals; (ii) observational studies
without a comparison group; (iii) a comparison group
including both subjects with and without IS and (iv)
studies that did not analyse the morphology or function
of the stomatognathic system.
Table 1 Search strategy used in each database.
Databases Search strategy
PubMed,
MEDLINE
(scoliosis[mh] OR scoliosis[tiab] OR idiopathic scoliosis[tiab] OR adolescent idiopathic scoliosis[tiab]) AND (temporomandibular joint
disorders[mh] OR temporomandibular joint disorders[tiab] OR stomatognathic diseases[mh] OR stomatognathic diseases[tiab] OR
craniomandibular disorders[mh] OR craniomandibular disorders[tiab] OR mandibular diseases[mh] OR mandibular diseases[tiab] OR dental
occlusion[mh] OR dental occlusion[tiab] OR malocclusion[mh] OR malocclusion[tiab] OR occlusal dysfunction[tiab] OR crossbite[tiab])
SCOPUS TITLE-ABS-KEY (‘scoliosis’ OR ‘idiopathic scoliosis’) AND TITLE-ABS-KEY (‘temporomandibular joint disorders’ OR ‘stomatognathic diseases’
OR ‘craniomandibular disorders’ OR ‘mandibular diseases’ OR ‘occlusal dysfunction’)
Web of Science TOPIC (*scoliosis* OR *idiopathic scoliosis*) AND TOPIC (*temporomandibular joint disorders* OR *stomatognathic diseases* OR
*mandibular diseases* OR *occlusal dysfunction*)
CINAHL Complete AB (scoliosis OR idiopathic scoliosis) AND AB (temporomandibular joint disorders OR stomatognathic diseases OR mandibular diseases OR
occlusal dysfunction)
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 773
Data extraction
Two authors (ICP and FGB) independently collected data
from the included studies in a standardized Microsoft
Excel data-collection form. To resolve disagreements,
a third author was consulted (RLV). We extracted the
following data: authorship, publication date, country,
total sample size, number of participants in each group
(cases and controls or healthy subjects), age, sex and
time since diagnosis. We collected data on the variable
of interest, the measurement tool used, and the main
ndings reported by each study.
Outcomes
The main variable was the count of subjects with and
without scoliosis in which the presence of malocclusion
was determined by Angle’s class or the presence of
transverse malocclusion as both unilateral and bilateral
crossbite. In Angle’s classication, class I corresponds
to the standard occlusion called orthognathia, class
II (divisions 1 and 2) corresponds to a retrognathia or
short jaw, and class III corresponds to an elongation of
the jaw called prognathism (19). Measures such as open
bite or overjet as well as diagnosis of temporomandibular
disorder were also of interest. The overjet can be dened as
the horizontal distance in millimetres between the upper
and lower incisors (20). We also intended to analyse the
prevalence of scoliosis in subjects who did or did not have
stomatognathic alterations.
Methodological quality assessment
To evaluate the quality of the studies included in this
review, the Newcastle–Ottawa Scale (NOS) was applied
(21). The domains explored by this scale are ‘selection
of study groups’ (maximum, 4 stars), ‘comparability
of groups’ (maximum, 2 stars) and ‘ascertainment of
exposure/outcome’ (maximum, 3 stars). The quality
classication of the included studies according to NOS
score is low (score 1–3), moderate (score 4–6), and high
quality (score 7–9) (22). Quality scores ranged from 0
(lowest) to 9 stars (highest) (23).
Statistical analysis
Two researchers were responsible for the design and
development of the statistical analysis (EOG and RLV). Due
to the heterogeneity in pathologic conditions and their
characteristics and following the recommendations of
Cooperetal. (2009) (24), we chose the DerSimonian and
Laird random effects model to estimate the overall pooled
effect with its 95% CI to improve the generalizability of
the ndings (25). For continuous variables, the pooled
effect was estimated using Cohen’s standardized
mean difference (SMD) calculation (26), which can
be interpreted in three levels of effect intensity: small
(SMD = 0.2), medium (SMD = 0.5) and large (SMD > 0.8)
(27). To analyse the prevalence of occlusal disorders in
scoliosis cases vs healthy controls and the prevalence of
scoliosis in patients with and without stomatognathic
disorders, we calculated the prevalence odds ratio (OR)
together with its 95% CI. The ndings were displayed
graphically using forest plots resulting from each analysis
(28). Heterogeneity analysis was performed by calculating
the Higgins Q-test and degree of inconsistency (I2),
which classies heterogeneity as low (<25%), medium
(25–50%) or large (>50%), as well as by calculating
its P-value (P < 0.1 indicates high heterogeneity) (29,
30). Risk of publication bias was assessed using funnel
plot asymmetry (31) and Egger’s test (P < 0.1 indicates
possible risk of publication bias) (32). We used MedCalc
Statistical software to carry out the analysis (MedCalc®
Statistical Software version 20.110, MedCalc Software
Ltd, Ostend, Belgium; https://www.medcalc.org; 2022)
with a 95% CI.
Results
A total of 14 studies (33, 34, 35, 36, 37, 38, 39, 40, 41,
42, 43, 44, 45, 46) met the eligibility criteria and were
included in the review (Fig. 1). In total, 3018 subjects
were included with a mean age of 13.39 years. Of these
subjects, 823 were scoliosis cases who were compared
to 1898 healthy controls and 133 subjects with occlusion
disorder who were compared to 164 subjects without
malocclusion. Table 2 shows the main characteristics of
the included studies, and Table 3 shows the quality of
the included studies assessed with the Newcastle‒Ottawa
Scale.
Malocclusion in patients with IS
Angle’s class II
Six studies (33, 34, 39, 40, 41, 42) including 476 IS patients
and 1100 controls examined the presence of Angle’s class
II bite in both groups. The OR (2.052, 95% CI = 1.236–
3.406; P = 0.005) indicated a twofold higher rate of type 2
malocclusion in subjects with IS. Heterogeneity between
medium and large and a possible publication bias were
found. The data can be seen in Table 4 and are displayed
graphically in Fig. 2.
Crossbite
Six studies (33, 39, 40, 41, 42, 43) including 482 IS
patients and 1726 controls examined the presence of
crossbite in both groups. The OR (2.234, 95% CI = 1.639–
3.045; P < 0.0001) indicated a more than twofold higher
rate of crossbite in subjects with IS. The data did not show
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 774
any heterogeneity, and no signicant publication bias was
found. The data can be seen in Table 4 and are displayed
graphically in Fig. 3.
Overjet
Three studies (40, 44, 45) including 110 IS patients and
144 controls evaluated the mean overjet in both groups.
The SMD (0.405, 95% CI = 0.149–0.661; P = 0.002)
indicated a medium effect with more pronounced overjet
in IS patients. The data did not show any heterogeneity,
and no signicant publication bias was found. The data
can be seen in Table 4 and are displayed graphically in
Fig. 4.
Temporomandibular disorder
Two studies (35, 46) including 59 IS patients and 71
controls evaluated the presence of TMD by measuring
the mean Fonseca Anamnestic Index in both groups.
The SMD (1.153, 95% CI = 0.780 to 1.527; P < 0.0001)
was signicant but indicated a very small effect with a
higher dysfunction in IS patients. The data did not show
any heterogeneity, and a possible publication bias was
found. The data can be seen in Table 4 and are displayed
graphically in Fig. 5.
IS in patients with malocclusion
Any type of malocclusion
Three studies (36, 37, 38) including 133 patients and 164
controls examined the presence of IS in patients with
malocclusion. The OR (4.633, 95% CI = 1.467–14.628;
P = 0.010) indicated more than fourfold higher risk of IS in
subjects with any type of malocclusion. The data did not
show any heterogeneity, and no signicant publication
bias was found. The data can be seen in Table 4 and are
displayed graphically in Fig. 6.
Discussion
Research into IS that helps to understand the aetiological
factors and increase the treatment success rate is needed.
Evidence points to a multifactorial aetiology, which
results in a challenging multidisciplinary approach. To
the best of our knowledge, this is the rst meta-analysis to
analyse the relationship between IS and stomatognathic
alterations. Our search found 14 studies that investigated
these relationships, nding a signicant relationship
between the presence of Angle’s class II and crossbite in
subjects with IS, a greater distance between the upper
and lower incisors (overjet), and greater dysfunction
due to TMD. It was also found that among subjects with
malocclusion, the prevalence of IS could be four times
higher than among subjects with normocclusion.
The studies found and included in our review were
mostly cross-sectional studies that failed to provide
a temporal relationship between the presence of
stomatognathic disorders and the appearance of IS,
so our ndings cannot be interpreted as a clear causal
relationship. However, our ndings can be interpreted in
the context of some longitudinal investigations in which
the causal relationship can be glimpsed. In fact, one of
the papers included in our review (35) provided data
from a retrospective cohort of subjects with hereditary
orthodontic anomalies in which a prevalence of scoliosis
of 20% was found, which is 14 times higher than the
prevalence in the population of reference, estimated at
1.4%. In isolated studies such as this one, some degree
of causation can be estimated as long as the orthodontic
abnormalities were present before the onset of the
scoliotic curve.
Several authors have investigated the causal
relationship between dental occlusion and spines in
animals. D’Attilioetal. (2014) applied a resin pad on the
right molar of rats. The result showed the development of
a spinal scoliotic curve in just a week, a condition that was
restored in 83% of rats in another week after changing
the resin pad to the opposite side molar (47). Similar
results were observed in another study, which performed
a unilateral molar extraction in rats that caused an
Figure1
Preferred Reporting Items for Systematic Reviews and Meta-
Analyses (PRISMA) ow chart for the systematic literature search
and study selection process.
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 775
alteration of normal spinal curves (48). These ndings
clearly suggest that the postural inputs recorded by the
trigeminal nerve deeply inuence the spinal curvature,
probably by producing an alteration in the erector spinal
muscular tone (49).
A recent systematic review by Langellaetal. focused
on the association between malocclusion and spinal
deformity and determined that the literature tends to
support a higher prevalence of occlusal alterations in
IS patients (13). Despite this, the authors moderate this
conclusion, as the studies used presented a high risk of
bias (13). The variability and heterogeneity of the nine
studies reported by Langella et al. do not allow us to
reach a denitive conclusion or perform any statistical
integration of the results. Our review is supported by 14
observational studies that allow us to state consistent
conclusions based on the presence of stomatognathic
alterations and the statistical integration of the results.
Some orthodontic interventions have been performed
in patients with spine deviations to assess the possible
relationship. Lippoldetal. concluded that early treatment
by maxillary expansion therapy for lateral posterior
Table 2 Main characteristics of the included studies.
Study Country
Study type Measurements
Subjects Controls
Total, nF, nAge†, years Total, nF, nAge†, years
Huggare etal. (44)Finland CSS Archs width, overbite,
overjet
22 16 17.8 (12–34) 22 17.8 (12–34)
Pećina etal. (43)Yugoslavia CSS Deep bite, crossbite,
open bite
202 173 7–17 640 350 7–17
Ben-Bassat etal. (33)Israel CSS Angle’s class, midline
deviation
96 79 13.9 ± 3.5 703 – –
Segatto etal. (40)Hungary/
Germany
CCS Angle’s class, overjet,
overbite, midline
deviation
28 – 14.7 ± 2.3 68 – 14.8 ± 0.11
Kostenko etal. (34)Ukraine CSS Angle’s class,
dentognathic
anomalies
200 169 12–15 25 21 12–15
Laskowska etal. (39)Poland CSS Angle’s class, crossbite,
open bite, deep bite
80 71 14.2 ± 2.03 61 29 12.6 ± 1.9
Sambataro etal. (42)Italy CSS Angle’s class, crossbite,
midline deviation
18 11 9.8 ± 0.8 10 2 14 9.8 ± 0.8
Zhang etal. (41)China CSS Angle’s class, unilateral
crosbite, midline
deviation
58 51 14.8 (12.4–20.2) 152 – 15.2 (12.2–18.6)
Lewandowska etal. (45)Poland CSS Overjet, canine
deviation, midline
deviation
60 60 14.0 ± 1.3 54 54 14.3 ± 1.6
Glowacki etal. (35)Poland CSS TMD disability,
Fonseca AI
30 30 12.43 ± 1.83‡42 42 12.43 ± 1.83‡
Uçar etal. (46)Tur key CSS Fonseca AI, Helkimo
Index
29 29 14.7 ± 1.9 29 29 14.9 ± 2.0
Lippold etal. (38)Germany CSS Angle’s class 22*– 5.0 ± 0.11 37 – 5.0 ± 0 .11
Korbmacher etal. (37)Germany CSS Unilateral crossbite 55 22 7.0 ± 2.08 55 – –
Sofyanti etal. (36)Indonesia ROS Angle’s class 56*22.36 ± 3.02 72 – 22.1 ± 3.01
*Class II/III; †values are mean ± .. or range; ‡age at start.
AI, Anamnestic Index; CCS, case–control study; CSS, cross-sectional study; F, females; ROS, retrospective observational study; TMD, temporomandibular disorder.
Table 3 Newcastle–Ottawa Scale (NOS) score for methodological quality assessment of observational studies.
Study S1 S2 S3 S4 C E1 E2 E3 Total scale Quality
Ben-Bassat etal. (33)* * * – * * * – 6 Moderate
Glowacki etal. (35)– * * * ** * * * 8 High
Huggare etal. (44)* * * * ** * * * 9 High
Korbmacher etal. (37)– * – – ** * – * 5 Moderate
Kostenko etal. (34)* – – – ** * * * 6 Moderate
Laskowska etal. (39)* * – * ** * * * 8 High
Lewandowska etal. (45)* * * * ** * * * 9 High
Lippold etal. (38)* * * * ** * – * 8 High
Pecina etal. (43)* * * * ** * * * 9 High
Sambataro etal. (42)* * * * * * – * 8 High
Segatto etal. (40)* * – * ** * * – 7 High
Sofyanti etal. (36)* * – – ** * – * 6 Moderate
Uçar etal. (46)* * – – ** * * * 7 High
Zhang etal. (41)* * – * ** * * * 8 High
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 776
crossbite did not produce any signicant change in the
spinal curves of the 31 children in the intervention group
(50). On the other hand, Piancino et al. assessed the
effects of orthodontic therapy based on the rapid palatal
expansion technique on juvenile/adolescent idiopathic
scoliosis (51), observing that the Cobb angle worsened
in participants during the treatment when compared
with baseline and improved after removing the treatment
compared with the curve angle during the treatment.
Based on the previous information, we could expect that
not all spinal deformities are related to the stomatognathic
system (50) but almost all IS seems to be related to
this system (51). Our ndings agree with the study by
Piancino et al. (51) as we observed that subjects with
malocclusion present up to four times higher prevalence
of scoliosis.
The ndings of this review could be explained by the fact
that the altered inputs from the stomatognathic system of
patients with malocclusion are recorded by the trigeminal
nerve, so the central nervous system could process an
output or postural response that inuences spine muscle
tone (49, 52). In contrast, we found that subjects with
IS present greater temporomandibular dysfunction and
have twice the risk of suffering from occlusion disorders
such as overjet in the incisors. Although these associations
do not allow us to determine the direction in which the
inuence between temporomandibular disorder and
scoliosis occurs, they do show a clear feedback inuence.
Nonetheless, the literature supports that the aetiology
of AIS could be varied, as there is not an exclusive and
common cause. The rst hypothesis to be considered
was a growth and/or development disorder due to
its appearance during adolescence or childhood (4).
Zhu et al. observed a vitamin D deciency among
Table 4 Main results of the all meta-analyses.
K Scoliosis Controls nSMD OR 95% CI t z P
Heterogeneity Publication bias
Q test I2Egger P
Overjet 3 11 0 14 4 254 0.405 0.149–0.661 3.11 6 0.002 0.3679 0.00% −1.3502 0.5158
Fonseca 2 59 71 130 1.153 0.780 – 1.527 6.111 <0.001 0.0003 0.00% −0.2823 <0.0001
Class II 6 241/ 476 402/1100 1576 2.052 1.236–3.406 2.779 0.005 12.1153 58.73% 3.2379 0.0605
Crossbite 6 96/482 256/1726 2208 2.234 1.639–3.045 5.089 <0.001 0.4146 0.00% 0.2540 0.4667
Scoliosis 3 14/133*4/164 297 4.633 1.467–14.628 2.614 0.009 0. 4345 0.00% −0. 1617 0.9491
*Malocclusion.
I2, degree of inconsistency; K, number of comparisons; OR, odds ratio; SMD, standardized mean difference; t, t-value.
Figure2
Forest plot showing the odds of subjects with scoliosis to suffer
from Angle’s class II.
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 777
subjects with IS that could inuence the regulation of
calcium–phosphorus metabolism, a condition that would
affect the normal growth of human bone (6) Several
genetic associations have been shown, nding up to 20
loci signicantly associated with IS (5). Among them, a
gene polymorphism of melatonin receptor 1B is present
in subjects with IS, which seems to be related to the
appearance of the deformity but not the severity of the
curve (7).
Further recent research suggested a deeper origin
related to how postural information is managed by the
central nervous system. The stomatognathic system,
which we address in this study, the vestibular system
(8) and the visual system (53) must be considered.
Ulusoyetal. found signicant differences in the macular
choroidal thickness of children with IS. The thinner the
choroidal thickness is, the more severe the scoliosis
angle (53). Karaca et al. showed that the thinness
of the choroid can cause anisometropic amblyopia,
which implies an asymmetry of vision in both eyes that
could cause the development of the scoliotic curve
(54). Another recent study found an increased risk
of developing scoliosis in children with strabismus,
indicating a possible causal relationship between
visual disturbances and spinal disorders (55). With
respect to the vestibular system, Cortés-Pérez et al.
reported that the presence of morphological alterations
of the vestibular system is signicantly related to
scoliosis (56). However, not only could morphological
alterations of the vestibular system be derived in IS but
Figure3
Forest plot showing the odds of scoliosis subjects to suffer from
crossbite.
Figure4
Forest plot showing the SMD of overjet in subjects with or
without IS.
Figure5
Forest plot SMD of Fonseca Anamnestic Index score between
subjects with or without IS.
Figure6
Forest plot showing the odds of scoliosis in subjects with or
without malocclusion.
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 778
also alterations in vestibular function according to Le
Berreetal., who observed alterations in the perception
of the gravitational vertical in IS subjects (8). The sum of
this evidence forces us to consider IS a multi-aetiological
disorder that requires a deep and detailed evaluation to
understand what approach will offer the best benet to
the patient.
This review has some limitations derived mainly from
the type of included studies. First, the inclusion of cross-
sectional studies does not allow the establishment of
causal relationships between scoliosis and alterations of
the stomatognathic system. Second, some meta-analyses
in this review included a small number of studies and
subjects, precluding conclusive results. Third, some meta-
analyses in this review showed some publication bias,
which also limits the scope of the conclusions drawn. In
the future, studies that investigate the temporal sequence
of cause and effect between disorders of the spine and
the stomatognathic system and analytical observational
studies, mainly prospective cohorts, that analyse the
inuence of occlusal manipulations on the scoliotic curve
should be carried out.
Conclusions
Subjects with scoliosis have twice the odds of having
occlusion disorders, such as Angle class II and crossbite,
than subjects without scoliosis. Patients with IS also
present a greater distance or overjet between the upper
and lower incisors, as well as greater dysfunction due
to temporomandibular disorders. On the other hand,
the prevalence of IS among subjects with malocclusion
could be up to four times higher. The data are especially
consistent regarding the relationship between crossbite
and scoliosis and, with a much smaller sample, in
the higher prevalence of IS in subjects with any type
of malocclusion, since these two analyses did not
show heterogeneity or publication bias. In light of the
results of this review, it can be recommended to start
new prospective studies with a sufcient sample to
investigate the possible causal relationship between
disorders of the stomatognathic system and IS. The
inclusion of the orofacial examination and the search
for temporomandibular dysfunction in the evaluation
protocols of patients with IS is also justied.
ICMJE conict of interest statement
The authors declare that there is no conict of interest that could be perceived
as prejudicing the impartiality of the research reported.
Funding statement
This research did not receive any specic grant from any funding agency in the
public, commercial, or not-for-prot sector.
References
1. AltafF, GibsonA, DannawiZ & NoordeenH. Adolescent idiopathic scoliosis. BMJ
2013 346 f2508. (https://doi.org/10.1136/bmj.f2508)
2. Romano M, Minozzi S, Zaina F, Saltikov JB, Chockalingam N,
KotwickiT, HennesAM & Negrini S. Exercises for adolescent idiopathic scoliosis:
a cochrane systematic review. Spine 2013 38 E883–E893. (https://doi.org/10.1097/
BRS.0b013e31829459f8)
3. SudA & TsirikosAI. Current concepts and controversies on adolescent idiopathic
scoliosis: Part I. Indian Journal of Orthopaedics 2013 47 117–128. (https://doi.
org/10.4103/0019-5413.108875)
4. DimeglioA & CanaveseF. The immature spine: growth and idiopathic scoliosis.
Annals of Translational Medicine 2020 8 22. (https://doi.org/10.21037/atm.2019.11.134)
5. KouI, Otomo N, TakedaK, MomozawaY, LuHF, KuboM, Kamatani Y,
OguraY, TakahashiY, NakajimaM, etal. Genome-wide association study identifies
14 previously unreported susceptibility loci for adolescent idiopathic scoliosis in Japanese.
Nature Communications 2019 10 3685. (https://doi.org/10.1038/s41467-019-11596-w)
6. Zhu Q, Chen J, Chen C, Wang H & Yang S. Association between calcium-
phosphorus balance and adolescent idiopathic scoliosis: a meta-analysis. Acta
Orthopaedica et Traumatologica Turcica 2019 53 468–473. (https://doi.org/10.1016/j.
aott.2019.08.012)
7. QiuXS, TangNLS, YeungHY, LeeKM, HungVWY, NgBKW, MaSL, KwokRH,
QinL, QiuY, et al. Melatonin receptor 1B (MTNR1B) gene polymorphism is associated
with the occurrence of adolescent idiopathic scoliosis. Spine 2007 32 1748–1753.
(https://doi.org/10.1097/BRS.0b013e3180b9f0ff)
8. Le BerreM, PradeauC, BrouillardA, CogetM, MassotC & CatanzaritiJF.
Do adolescents with idiopathic scoliosis have an erroneous perception of the gravitational
vertical? Spine Deformity 2019 7 71–79. (https://doi.org/10.1016/j.jspd.2018.05.004)
9. Zagalaz-AnulaN, León-MorillasF, Andradre-OrtegaJA, Ibáñez-VeraAJ,
de Oliveira-Sousa SL & Lomas-Vega R. Case report: conservative treatment of
adolescent idiopathic scoliosis can alter the perception of verticality. A preliminary study.
Frontiers in Pediatrics 2020 8 609555. (https://doi.org/10.3389/fped.2020.609555)
10. DufvenbergM, AdeyemiF, RajendranI, ObergB & AbbottA. Does postural
stability differ between adolescents with idiopathic scoliosis and typically developed? A
systematic literature review and meta-analysis. Scoliosis and Spinal Disorders 2018 13 19.
(https://doi.org/10.1186/s13013-018-0163-1)
11. CatanzaritiJF, AgnaniO, GuyotMA, Wlodyka-DemailleS, KheniouiH &
DonzeC. Does adolescent idiopathic scoliosis relate to vestibular disorders? A systematic
review. Annals of Physical and Rehabilitation Medicine 2014 57 465–479. (https://doi.
org/10.1016/j.rehab.2014.04.003)
12. Ferrillo M, Marotta N, Giudice A, Calaore D, Curci C, Fortunato L,
AmmendoliaA & de SireA. Effects of occlusal splints on spinal posture in patients with
temporomandibular disorders: a systematic review. Healthcare 2022 10 739. (https://doi.
org/10.3390/healthcare10040739)
13. LangellaF, FusiniF, RossiG, VillafañeJH, Migliaccio N, Donzelli S &
BerjanoP. Spinal deformity and malocclusion association is not supported by high-
quality studies: results from a systematic review of the literature. European Spine Journal
2019 28 1638–1651. (https://doi.org/10.1007/s00586-019-05896-4)
14. Oliveira SSI, Pannuti CM, Paranhos KS, Tanganeli JPC, Laganá DC,
Sesma N, Duarte M, Frigerio MLMA & Cho SC. Effect of occlusal splint and
therapeutic exercises on postural balance of patients with signs and symptoms of
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 779
temporomandibular disorder. Clinical and Experimental Dental Research 2019 5 109–115.
(https://doi.org/10.1002/cre2.136)
15. Paya-ArgoudM, Tardieu C, Cheynet F, RaskinA & Borel L. Impact of
orthognathic surgery on the body posture. Gait and Posture 2019 67 25–30. (https://doi.
org/10.1016/j.gaitpost.2018.09.019)
16. Stroup DF, Berlin JA, Morton SC, Olkin I, Williamson GD, Rennie D,
MoherD, BeckerBJ, SipeTA & ThackerSB. Meta-analysis of observational studies
in epidemiology: a proposal for reporting. Meta-analysis Of Observational Studies in
Epidemiology (MOOSE) group. JAMA 2000 283 2008–2012. (https://doi.org/10.1001/
jama.283.15.2008)
17. PageMJ, McKenzieJE, BossuytPM, BoutronI, HomannTC, MulrowCD,
ShamseerL, TetzlaJM, AklEA, BrennanSE, etal. The PRISMA 2020 statement:
an updated guideline for reporting systematic reviews. BMJ 2021 372 n71. (https://doi.
org/10.1136/bmj.n71)
18. Higgins J & Green S Cochrane Handbook for Systematic Reviews of Interventions.
London: The Cochrane Collaboration 2011.
19. SaccucciM, TettamantiL, MummoloS, PolimeniA, FestaF & TeccoS.
Scoliosis and dental occlusion: a review of the literature. Scoliosis 2011 6 15. (https://doi.
org/10.1186/1748-7161-6-15)
20. ErgiegSO, SudhirV, ShibuT, FanasS & AshokM. The mean overjet in libyan
children and the relationship between increased overjet and incisors trauma. Indian Journal
of Dental Research 2020 31 967. (https://doi.org/10.4103/ijdr.ijdr_361_19)
21. WellsG, SheaB & O’ConnelD. The Newcastle-Ottawa Scale (NOS) for Assessing
the Quailty of Nonrandomised Studies in Meta-analysis 2009. Available at: http: //www .ohri
.ca/p rogra ms/cl inica l_epi demio logy/ oxfor d.asp
22. StangA. Critical evaluation of the Newcastle-Ottawa scale for the assessment of the
quality of nonrandomized studies in meta-analyses. European Journal of Epidemiology 2010
25 603–605. (https://doi.org/10.1007/s10654-010-9491-z)
23. LoCK-L, MertzD & LoebM. Newcastle-Ottawa Scale: comparing reviewers’ to
authors’ assessments. BMC Medical Research Methodology 2014 14 45. (https://doi.
org/10.1186/1471-2288-14-45)
24. CooperH, LarryH & ValentineJ. The Handbook of Research Synthesis and Meta-
analysis. New York: Russell Publishing Sage Foundation 2009.
25. DerSimonianR & LairdN. Meta-analysis in clinical trials. Controlled Clinical Trials
1986 7 177–188. (https://doi.org/10.1016/0197-2456(86)90046-2)
26. Cohen J. Statistical Power Analysis for the Behavioral Sciences. New York: Academic
Press 1977.
27. Faraone SV. Interpreting estimates of treatment effects: implications for managed
care. P and T 2008 33 700–711.
28. Rücker G & Schwarzer G. Beyond the forest plot: the drapery plot. Research
Synthesis Methods 2021 12 13–19. (https://doi.org/10.1002/jrsm.1410)
29. Higgins J, Thompson S, Deeks J & Altman D. Statistical heterogeneity
in systematic reviews of clinical trials: a critical appraisal of guidelines and practice.
Journal of Health Services Research and Policy 2002 7 51–61. (https://doi.
org/10.1258/1355819021927674)
30. Higgins JPT, Thompson SG, Deeks JJ & Altman DG. Measuring
inconsistency in meta-analyses. BMJ 2003 327 557–560. (https://doi.org/10.1136/
bmj.327.7414.557)
31. SterneJAC & EggerM. Funnel plots for detecting bias in meta-analysis: guidelines
on choice of axis. Journal of Clinical Epidemiology 2001 54 1046–1055. (https://doi.
org/10.1016/s0895-4356(01)00377-8)
32. EggerM, SmithGD, SchneiderM & MinderC. Bias in meta-analysis detected
by a simple , graphical test measures of funnel plot asymmetry. BMJ 1997 315 629–634.
(https://doi.org/10.1136/bmj.315.7109.629)
33. Ben-BassatY, YitschakyM, Kaplan L & BrinI. Occlusal patterns in patients
with idiopathic scoliosis. American Journal of Orthodontics and Dentofacial Orthopedics
2006 130 629–633. (https://doi.org/10.1016/j.ajodo.2005.01.032)
34. KostenkoYY, MelnykVS, HorzovLF & PotapchukAM. Relationship between
idiopathic scoliosis of the spine and dentognathic anomalies in adolescents. Wiadomosci
Lekarskie 2019 72 2117–2120. (https://doi.org/10.36740/WLek201911111)
35. GlowackiJ, LatuszewskaJ, OkretA, SkowronN, MisterskaE & Opydo-
SzymaczekJ. Temporomandibular joint disorders in females with adolescent idiopathic
scoliosis: long-term effects of Milwaukee brace treatment. Journal of Clinical Medicine 2022
11. (https://doi.org/10.3390/jcm11061721)
36. SofyantiE, BoelT & SihombingARN. The correlation between back posture
and sagittal jaw position in adult orthodontic patients. Journal of Taibah Universit y Medical
Sciences 2021 16 63–69. (https://doi.org/10.1016/j.jtumed.2020.10.009)
37. KorbmacherH, KochL, Eggers-StroederG & Kahl-NiekeB. Associations
between orthopaedic disturbances and unilateral crossbite in children with asymmetry of
the upper cervical spine. European Journal of Orthodontics 2007 29 100–104. (https://
doi.org/10.1093/ejo/cjl066)
38. LippoldC, van den BosL, HohoA, DaneshG & EhmerU. Interdisciplinary
study of orthopedic and orthodontic findings in pre-school infants. Journal of Orofacial
Orthopedics / Fortschritte der Kieferorthopädie 2003 64 330–340. (https://doi.
org/10.1007/s00056-003-0236-4)
39. Laskowska M, Olczak-Kowalczyk D, Zadurska M, Czubak J, Czubak-
WrzosekM, WalerzakM & TyrakowskiM. Evaluation of a relationship between
malocclusion and idiopathic scoliosis in children and adolescents. Journal of Children’s
Orthopaedics 2019 13 600–606. (https://doi.org/10.1302/1863-2548.13.190100)
40. SegattoE, Lippold C & Végh A. Craniofacial features of children with spinal
deformities. BMC Musculoskeletal Disorders 2008 9 169. (https://doi.org/10.1186/1471-
2474-9-169)
41. ZhangH, Ma J, Zhang Z, FengY, CaiC & Wang C. Occlusal deviations in
adolescents with idiopathic and congenital scoliosis. Korean Journal of Orthodontics 2022
52 165–171. (https://doi.org/10.4041/kjod21.259)
42. SambataroS, BocchieriS, CervinoG, La BrunaR, CicciùA, InnortaM,
TorrisiB & Cicciù M. Correlations between malocclusion and postural anomalies in
children with mixed dentition. Journal of Functional Morphology and Kinesiology 2019 4
45. (https://doi.org/10.3390/jfmk4030045)
43. Pećina M, Lulić-Dukić O & Pećina-Hrncević A. Hereditary orthodontic
anomalies and idiopathic scoliosis. International Orthopaedics 1991 15 57–59. (https://
doi.org/10.1007/BF00210536)
44. HuggareJ, PirttiniemiP & SerloW. Head posture and dentofacial morphology
in subjects treated for scoliosis. Proceedings of the Finnish Dental Society. Suomen
Hammaslaakariseuran Toimituksia 1991 87 151–158.
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company

www.efortopenreviews.org
8:10
SPINE 780
45. Lewandowska J, Opydo-Szymaczek J, Mehr K & Głowacki J. Bilateral
dentoalveolar asymmetries in female patients with adolescent idiopathic scoliosis. Acta
of Bioengineering and Biomechanics 2019 21 53–62. (https://doi.org/10.37190/ABB-
01457-2019-01)
46. Uçar İ, Batın S, Arık M, Payas A, Kurtoğlu E, Karartı C, Seber T,
Çöbden SB, Taşdemir H & Unur E. Is scoliosis related to mastication muscle
asymmetry and temporomandibular disorders? A cross-sectional study. Musculoskeletal
Science and Practice 2022 58 102533. (https://doi.org/10.1016/j.msksp.2022.102533)
47. D’AttilioM, FilippiMR, FemminellaB, FestaF & TeccoS. The influence of
an experimentally-induced malocclusion on vertebral alignment in rats: a controlled pilot
study. Cranio 2005 23 119–129. (https://doi.org/10.1179/crn.2005.017)
48. Ramirez-Yanez GO, Mehta L & Mehta NR. The effect of dental occlusal
disturbances on the curvature of the vertebral spine in rats. Cranio 2015 33 217–227.
(https://doi.org/10.1179/2151090314Y.0000000017)
49. Wilczyński J. Relationship between muscle tone of the erector spinae and the
concave and convex sides of spinal curvature in low-grade scoliosis among children.
Children 2021 8. (https://doi.org/10.3390/children8121168)
50. LippoldC, Moiseenko T, Drerup B, Schilgen M, Végh A & Danesh G.
Spine deviations and orthodontic treatment of asymmetric malocclusions in children. BMC
Musculoskeletal Disorders 2012 13 151. (https://doi.org/10.1186/1471-2474-13-151)
51. Piancino MG, MacDonald F, Laponte I, Cannavale R, Crincoli V &
DalmassoP. Juvenile/adolescent idiopatic scoliosis and rapid palatal expansion. A pilot
study. Children 2021 8. (https://doi.org/10.3390/children8050362)
52. Cuccia A & Caradonna C. The relationship between the stomatognathic
system and body posture. Clinics 2009 64 61–66. (https://doi.org/10.1590/s1807-
59322009000100011)
53. Ulusoy DM, Akkaya S & Batın S. Evaluation of choroidal changes in
adolescent idiopathic scoliosis using enhanced depth imaging optical coherence
tomography. Clinical and Experimental Optometry 2020 103 320–323. (https://doi.
org/10.1111/cxo.12932)
54. KaracaEE, Çubuk MÖ, Akçam HT, UzunF & Yüksel E. Choroidal thickness
in Turkish children with anisometric amblyopia. Seminars in Ophthalmology 2017 32
291–296. (https://doi.org/10.3109/08820538.2015.1068343)
55. ZhuB, WangX, FuL & YanJ. Pattern strabismus in a tertiary hospital in Southern
China: a retrospective review. Medicina (Kaunas) 2022 58. (https://doi.org/10.3390/
medicina58081018)
56. Cortés-Pérez I, Salamanca-Montilla L, Gámiz-Bermúdez F, Obrero-
GaitánE, Ibáñez-VeraAJ & Lomas-VegaR. Vestibular morphological alterations in
adolescent idiopathic scoliosis: a systematic review of observational studies. Children 2022
10. (https://doi.org/10.3390/children10010035)
SPINESPINE
Downloaded from Bioscientifica.com at 10/04/2023 08:40:53AM
via Eli Lilly & Company