10.59987/ads/2012.3-4.95-99
Background. Rocabado’s hyoid triangle is the only cephalometric parameter that can assess the effects of orthodontic treatment on tongue posture. Aim. To evaluate the restoration of tongue posture and function by conducting a cephalometric assessment of the hyoid triangle before and after rapid maxillary expansion. Methods. Sixtyfour healthy patients aged 6-11 years with skeletal class II malocclusion, mixed dentition, and infantile swallowing took part in this study. They submitted to lateral cephalometric radiography before and after orthodontic maxillary rapid expansion, in order to assess the resulting changes in the proportions of the hyoid triangle (following Rocabado’s parameters). The cephalometric findings were compared according to sex, age, and divergence using the chi-square McNemar test at the 5% significance level (p&lt;0.05). Results. The orthodontic treatment resulted an improvement from skeletal class II malocclusion to class I, with elimination of infantile swallowing in 81.8% of male patients [95% confidence interval (CI)=61.5–92.7%], in 87.1% of patients aged 6–7 years (95% CI=71.1–94.9%). Conclusions. This cephalometric analysis revealed that the hyoid riangle was modified by the orthodontic maxillary expansion, reconditioning of tongue posture and function particularly among male, aged 6-7 years old with skeletal class II malocclusion, mixed dentition, and infantile swallowing.
application/pdf
1971-1441
158
3-4
en
A. Polimeni 
https://creativecommons.org/licenses/by-nc-nd/4.0
Annali di stomatologia
hyoid triangle
Cephalometric evaluation of the hyoid triangle before and after maxillary rapid expansion in patients with skeletal class II, mixed dentition, and infantile swallowing
Text.Serial.Journal
https://www.annalidistomatologia.eu/ads
3
Original Article
2022-08-17
2022-08-17
2012-12-01
2023-12-04
95-99
Ann Stomatol (Roma)
A. Polimeni 
2012
10.59987/ads/2012.3-4.95-99
95
1971-1441
3-4
hyoid triangle
en
99
Cephalometric evaluation of the hyoid triangle before and after maxillary rapid expansion in patients with skeletal class II, mixed dentition, and infantile swallowing
https://www.annalidistomatologia.eu/ads/article/download/158/141
3
                                                                                                         Original article


Cephalometric evaluation of the hyoid triangle
before and after maxillary rapid expansion
in patients with skeletal class II, mixed dentition,




                                                                                                li
and infantile swallowing




                                                                                             na
Valeria Parisella, DDS1                                         Introduction
Iole Vozza, DDS, PhD1




                                                                                          io
Francesca Capasso, DDS1                                         The tongue plays an indispensable role during all stages
Valeria Luzzi, DDS, PhD1                                        of embryonic development. With every act of swallowing,
Gaetano Ierardo, DDS, PhD1                                      contact of the tongue against the palate determines the
Italo Nofroni, MD2                                              correct expansion of the latter, and its absence results in




                                                                                       az
Antonella Polimeni, MD, DDS1                                    failure of the palate to form correctly, such as in Pierre
                                                                Robin syndrome (1). Rocabado’s hyoid triangle is the
                                                                only cephalometric parameter that can be used to assess
1
    Oral and Maxillofacial Sciences Department,                 the effects of orthodontic treatment of tongue posture (2).




                                                                        n
    Sapienza University of Rome                                 The hyoid bone is located at the root of the tongue, and
2
    Experimental Medicine Department,                           is the only bone of the human body that is not articulated




                                                                     er
    Sapienza University of Rome                                 with any other bone. It is located at the fourth cervical ver-
                                                                tebra and is held in place by several muscular formations.
                                                                Its position in the frontal area of the neck is divided into
Corresponding author:
Iole Vozza DDS, PhD
Oral and Maxillofacial Sciences Department
Sapienza University of Rome
                                               nt               cranial (suprahyoid) and caudal (subhyoid) regions. The
                                                                muscles of the subhyoid region generally contribute to
                                                                lowering of the hyoid bone, securing it in a more caudal
                                                                position than in the rest position. The suprahyoid mus-
                                             iI
Via Caserta 6                                                   cles, on the other hand, allow mandible lowering (if the
00161 Rome, Italy                                               hyoid bone has been set caudally in advance) or raising
Phone: +39 06 49976619                                          of the hyoid bone (followed by raising of the larynx, at-
                                           on

E-mail: iole.vozza@uniroma1.it                                  tached to the hyoid bone) (3). This bone is indispensa-
                                                                ble for speech and chewing, and especially for jaw open-
                                                                ing. Swallowing is another important function, involving
Summary                                                         the upper airways and digestive tract. In this situation, the
                                 i


Background. Rocabado’s hyoid triangle is the only               mandible stabilizes itself on the maxilla, normally with a
                              iz


cephalometric parameter that can assess the effects of or-      centric occlusion; the tongue exerts its force balanced be-
thodontic treatment on tongue posture. Aim. To evaluate         tween the palate and the palatal surface of the upper
the restoration of tongue posture and function by conduct-      teeth. The tongue is a muscular complex comprising 16
              Ed




ing a cephalometric assessment of the hyoid triangle be-        smaller muscular bellies. Dynamic alterations of the
fore and after rapid maxillary expansion. Methods. Sixty-       tongue influence the horizontal position of the hyoid
four healthy patients aged 6-11 years with skeletal class II    bone and its different physiological actions and synergy
malocclusion, mixed dentition, and infantile swallowing         in both medium and long terms. The hyoid bone is the
took part in this study. They submitted to lateral cephalo-     bony support of the tongue, it has 24 muscle attach-
metric radiography before and after orthodontic maxillary       ments, and is related to the skull muscles (stylohyoid
 IC




rapid expansion, in order to assess the resulting changes       muscle and posterior belly of digastric muscle), the “fun-
in the proportions of the hyoid triangle (following Ro-         nel chest” (sternohyoid and sternothyroid muscles), and
cabado’s parameters). The cephalometric findings were           scapulae (omohyoid muscle). For these connections,
compared according to sex, age, and divergence using the
                                                                the hyoid bone is a center of coordination that signals the
C




chi-square McNemar test at the 5% significance level
                                                                brain and its related structures and allows mandibular
(p<0.05). Results. The orthodontic treatment resulted an im-
                                                                and cervical kinematics. Monitoring of tongue position is
provement from skeletal class II malocclusion to class I,
                                                                guaranteed by anastomosis of the hypoglossal nerve
with elimination of infantile swallowing in 81.8% of male pa-
                                                                with the first four cervical roots, rendering the cervical and
©




tients [95% confidence interval (CI)=61.5–92.7%], in 87.1%
of patients aged 6–7 years (95% CI=71.1–94.9%). Conclu-         lingual dynamics interdependent. The hyoid bone and
sions. This cephalometric analysis revealed that the hyoid      tongue are the links between oral functions and vertebral
triangle was modified by the orthodontic maxillary expan-       column functions. The hyoid bone is the protagonist in
sion, reconditioning of tongue posture and function partic-     the craniocervical–mandibular relationship, being con-
ularly among male, aged 6-7 years old with skeletal class       nected to the skull, tongue, jaw, cervical spine, clavicle,
II malocclusion, mixed dentition, and infantile swallowing.     scapula, pharynx, and larynx (4). It participates in
                                                                mandibular movements that occur during swallowing,
Key words: cephalometric evaluation, orthodontic treat-         chewing, respiration, and speaking, and it responds to
ment, infantile swallowing, mixed dentition, hyoid triangle.    vertebral muscle solicitations and postural changes. The

Annali di Stomatologia 2012; III (3/4): 95-99                                                                              95
V. Parisella et al.


tongue is the protagonist of temporomandibular joint de-        Materials and methods
velopment and modeling of the dental arches. It has a
morphogenetic role in the developmental stage because           From February 2011 to February 2012 1,152 patients pre-
it acts as a balance in the intermediate step and as a          sented to the Pediatric Dentistry Division, Sapienza Univer-
compensator in the adult stage. At the end of tooth erup-       sity of Rome for an orthodontic evaluation. All patients un-




                                                                                                 li
tion the tongue is located at the equator of the palatal sur-   derwent lateral cephalometric radiography in order to
faces of the incisors; that is coronal to the point corre-      execute a cephalometric analysis (Planmeca Romexis®,




                                                                                              na
sponding to the depth of the pits. In pathological              Planmeca, Finland). The X-ray was performed in occlusion
situations, the tongue diverts its posture to compensate        and without swallowing. For the present study, 64 healthy
and fill the vertical, frontal, and lateral spaces. The swal-   patients (22 males and 42 females), aged 6–11 years
lowing movement is preceded by preparation of the bo-           (mean age 7.76 years) with skeletal class II malocclusion,




                                                                                           io
lus in the oral cavity. True swallowing begins once the bo-     mixed dentition, and infantile swallowing were selected. The
lus has reached the center of the dorsal surface of the         infantile swallowing was assessed according to the Peng
tongue thanks mainly to contraction of the intrinsic lingual    method (9). According to the initial cephalometry executed
muscles and the styloglossus muscle. The tip of the             during the first orthodontic visit, the patients were divided




                                                                                        az
tongue (i.e., the apex) presses against the palate in the       into three groups: normodivergent (group A, n=22), hypo-
area between the back of the retroincisive papilla and the      divergent (group B, n=14), and hyperdivergent (group C,
first wrinkles of the palatine rugae (i.e., tongue position     n=28) patients. Then it was assessed the hyoid triangle
against the palate even at rest), and then movement of          cephalometrically (following Rocabado’s parameters). The




                                                                        n
the tongue dorsum progressively crushes from front to           triangle was drawn by joining the following points: RGN (the
back, inducing progression of the bolus toward the phar-        lowest and most posterior point of the symphysis), H (the




                                                                     er
ynx. The inability of the tongue to implement this action       highest and most anterior point of the hyoid bone), and VC3
for whatever reason (e.g., anatomic problems or dysfunc-        (the lowest and most anterior angle of the third cervical ver-
tional activity) impairs swallowing. Furthermore, there is      tebra). The cephalometric evaluation was performed by two


                                           nt
a functional correlation between the tongue and the first
cervical vertebrae, because tongue protrusion, retru-
sion, and torsion are associated with atlas protrusion,
retrusion, and torsion, respectively (5). The influence of
                                                                double-blinded examiners. The hyoid triangle was classi-
                                                                fied from 1 to 5 according to the form of the obtained trian-
                                                                gle as follows: 1=normal triangle, 2=narrow triangle,
                                                                3=elongated triangle, 4=normal inverted triangle, and
                                         iI
body posture on the posture of the head has been em-            5=narrow inverted triangle (Tab. 1). The patients were sub-
phasized in recent decades by Rocabado, who found a             jected to orthodontic treatment with rapid maxillary expan-
frequent association between second-class occlusion,            sion (RME) with an average active expansion of 15 +/- 2
                                       on

forward position of the head, decreased cervical lordosis,      days. 6.25 +/- 0.15 months after RME the patients re-
posterior rotation of mandible, and increased lower facial      peated the lateral cephalometric radiography in order to as-
height (6, 7). A cephalometric parameter proposed by            sess eventual tongue posture changes (the X-ray was
Bibby and Preston (8) and Rocabado (2) for evaluating           performed in occlusion and without swallowing).
                               i


the position of the hyoid bone from the mandible and the
                            iz


cervical spine, is based on a triangle constructed by
joining the following anatomical points:
              Ed




                                                                                             T1: normal triangle
•    H-point: the upper edge of the frontal area hyoid
     body;
•    The retrognathic (RGN) point: the posterior-lower
     point of the mandibular symphysis;
•    The VC3ai point: the anterior-lower point of the body                                   T2: narrow triangle
     of the third cervical vertebra (C3).
 IC




This triangle is assessed in a proportional and nonlinear
manner and is quantifiable by the projection of H onto the
VC3-RGN segment. The cephalometric position of the
C




hyoid bone depends on the posture of the tongue, the                                         T3: elongated triangle
mandible, and the spine. The triangle is positive when the
bone is at the top, but lower compared to the VC3ai-RGN
base, and vanishes and becomes negative during physi-
©




ological swallowing in hyperdivergent patients with a back
                                                                                             T4: normal inverted triangle
growth vector and cervical kyphosis (4). So the aim of this
study was to assess the restoration of tongue posture and
function by conducting a cephalometric assessment of the
hyoid triangle through lateral cephalometric radiography of
the skull in patients with skeletal class II malocclusion,                                   T5: narrow inverted triangle
mixed dentition, and infantile swallowing, characterized by
malocclusion with sagittal and transverse discrepancies,        Table 1. Classification of the hyoid triangle before orthodontic
before and after orthodontic treatment.                         treatment.


96                                                                                 Annali di Stomatologia 2012; III (3/4): 95-99
Cephalometric evaluation of the hyoid triangle before and after maxillary rapid expansion in patients with skeletal class II…


The cephalometric results of the triangle before and after
orthodontic treatment were compared according to sex,
age, and divergence, using the chi-square McNemar test
at the 5% significance level (p<0.05).




                                                                                                     li
Results




                                                                                                  na
Following orthodontic therapy with rapid maxillary ex-
pansion, 51 out of 64 subjects (79.7%) experienced suc-
cessful outcomes with complete resolution of infantile




                                                                                               io
deglutition, and a class I skeletal pattern was obtained.
The changes in the hyoid bone triangle differed between
the three groups as follows: a post-treatment turned over
and/or normal triangle (group A), a reduced post-treat-




                                                                                            az
ment turned over triangle (group B), and a reduced post-
treatment triangle that was not turned over before therapy
(group C). The improvement in tongue posture was re-
markable for patients who were classified as having a pre-




                                                                            n
treatment T5, T3, and T2 hyoid bone triangle (Figs. 1-6).          Figure 3. Normodivergent patient before therapy.




                                                                         er
                                               nt
                                             iI
                                 i         on
                              iz
              Ed




Figure 1. Hypodivergent patient before therapy.                     Figure 4. Normodivergent patient after therapy.
 IC
C
©




Figure 2. Hypodivergent patient after therapy.                      Figure 5. Hyperdivergent patient before therapy.


Annali di Stomatologia 2012; III (3/4): 95-99                                                                                   97
V. Parisella et al.


                                                                       treatment T3 hyoid bone triangle experienced a clinical
                                                                       improvement of their skeletal pattern class and tongue
                                                                       posture (95% CI=72.2–100.0%), with eight and two pa-
                                                                       tients achieving a T1 and T2 hyoid bone tri-
                                                                       angle, respectively. Table 2 gives the results of the 18 pa-




                                                                                                        li
                                                                       tients with a pretreatment T2 hyoid bone triangle: the
                                                                       triangle shape changed to T1 in 15 out of 18 patients




                                                                                                     na
                                                                       (83.3%; 95% CI=60.8–94.2%).
                                                                       The success of maxillary expansion therapy differed ac-
                                                                       cording to age, sex, and pretreatment clinical situation of
                                                                       the subjects. In 18 out of 22 (81.8%) male subjects and




                                                                                                  io
                                                                       33 out of 42 (78.6%) female subjects, the skeletal pattern
                                                                       switched from class II to class I (95% CI=61.5–92.7% and
                                                                       64.1–8.3%, respectively). Maxillary expansion was asso-
                                                                       ciated with a complete elimination of infantile deglutition




                                                                                               az
                                                                       and I class skeletal pattern (i.e., a desirable outcome) in
                                                                       27 out of 31 (87.1%) patients aged 6-7 years (95%
                                                                       CI=71.1–94.9%), but in only 24 out of 33 (72.7%) patients
                                                                       aged ≥8 years (95% CI=55.8–84.9%). Among the 22 pa-




                                                                                n
                                                                       tients with normodivergence, 19 (86.4%) changed to a
                                                                       class I skeletal pattern with complete elimination of infan-




                                                                             er
Figure 6. Hyperdivergent patient after therapy.
                                                                       tile deglutition (95% CI=66.7–95.3%). Following therapy,
                                                                       12 out of 14 (85.7%) hypodivergent individuals had a
Out of 27 individuals with a pretreatment T5 hyoid bone                positive clinical outcome (95% CI=60.1–96.0%). In addi-


                                                nt
triangle, 26 (96.3%) experienced a clinical improvement
[95% confidence interval (CI)=81.7–99.3%], with 14 and
12 subjects obtaining a T1 and T2 hyoid bone triangles,
respectively. All ten subjects (100%) classified with a pre-
                                                                       tion, 20 out of 28 (71.4%) individuals with hyperdiver-
                                                                       gence achieved a class I skeletal pattern with complete
                                                                       elimination of infantile deglutition (95% CI=52.9-84.7%).
                                                                       The findings are summarized in Table 3.
                                              iI
Triangle                   Number of patients             Number of patients who                 Percentage of patients with
                                            on

                            before treatment             improved after treatment               tongue posture improvement
                                                                                                      after treatment

T2                                  18                           15 (15T1)                       83.3% (95% CI=60.8–94.2%)
                                   i
                                iz


T3                                  10                         10 (8 T1–2 T2)                     100% (95% CI=72.2–100%)

T5                                  27                       26 (14 T1–12 T2)                    96.3% (95% CI=81.7–99.3%)
                 Ed




Table 2. Percentage of patients who improved after tongue posture treatment relative to the shape of the hyoid triangle.



    Patients               Number of patients               Number of patients                   Percentage of patients with
                            before treatment                with skeletal class I                skeletal class I and without
 IC




                                                              after treatment                infantile swallowing after treatment

    Male                            22                               18                          81.8% (95% CI=61.5–92.7%)
C




    Female                          42                               33                          78.6% (95% CI=64.1–88.3%)

    Younger than 7 years            31                               27                          87.1% (95% CI=71.1–94.9%)
©




    Older than 7 years              33                               24                          72.7% (95% CI=55.8–84.9%)

    Normodivergent                  22                               19                          86.4% (95% CI=66.7–95.3%)

    Hypodivergent                   14                               12                           85.7% (95% CI=60.1–96%)

    Hyperdivergent                  28                               20                          71.4% (95% CI=52.9–84.7%)

    Table 3. Percentage of patients who improved after tongue posture treatment according to sex, age, and divergence.


98                                                                                         Annali di Stomatologia 2012; III (3/4): 95-99
Cephalometric evaluation of the hyoid triangle before and after maxillary rapid expansion in patients with skeletal class II…


Discussion                                                         needed with a larger number of cases to confirm these
                                                                   findings.
The position of the tongue at rest is considered to have
a greater effect on the position of teeth than the short-term
pressure of perioral soft tissues (10). It has been shown          References




                                                                                                        li
that in patients with severe maxillary constriction, the
space required to accommodate the tongue close to the              1.    Robin P. La Glossopatose. Doin G (Ed), Editions Semaine




                                                                                                     na
roof of the palate is inadequate, and tongue posture is                  Dentaire, Paris, 1928.
lower than desirable (11). Because maxillary expansion             2.    Rocabado M. Biomechanical relationship of the cranial, cer-
                                                                         vical, and hyoid regions. J Craniomandibular Pract. 1983;
may create the additional space needed to accommodate
                                                                         1(3):61-6.
the tongue, it may be hypothesized that in patients with
                                                                   3.    Doual A, Léger JL, Doual JM, Hadjiat F. [The hyoid bone and




                                                                                                  io
stable results, the tongue may be spontaneously position-                vertical dimension]. Orthod Fr. 2003; 74(3):333-63.
ing itself closer to the roof of the palate. Not only might this   4.    Rocabado M, Iglarsh ZA. Musculoskeletal Approach to Max-
result in balanced cheek and tongue pressure on denti-                   illofacial Pain. J.B. Lippincott, Philadelphia, 1991.




                                                                                               az
tion but also in a modification of craniofacial growth and         5.    Rocabado M. Diagnosis and treatment of abnormal cranio-
development patterns (12). After orthopedic/functional                   cervical and cranio-mandibular mechanics. In: Solberg WK,
treatment to alter the jaw and improve its functional activ-             Clarck GE (Eds). Abnormal Jaw Mechanics Diagnosis and
ity, we observed an increase in the space available for the              Treatment. Quintessence, Chicago, 1984a.
correct positioning of the tongue and its posture. However,        6.    Rocabado M. Joint distraction with a functional maxillo-




                                                                              n
                                                                         mandibular orthopedic appliance. J Craniomandibular Pract.
it is important to emphasize that since lingual dysfunction
                                                                         1984;2(4):358-63.
is difficult to intercept and correct, it is important to pro-




                                                                           er
                                                                   7.    Rocabado M. The importance of soft tissue mechanics in sta-
vide these patients with myofunctional-logopedic rehabil-                bility and instability of the cervical spine: a functional diagno-
itation that guarantees stability of the final result achieved           sis for treatment planning. Cranio 1987;5(2):130-8.
with the aid of orthodontic treatment (13). The cephalo-           8.    Bibby RE, Preston CB. The hyoid triangle. Am J Orthod.



                                               nt
metric analysis of patients at the beginning of therapy re-
vealed a reversed triangle hyoid (i.e., with the top facing
upward); this indicates an incorrect tongue posture, but is
a common physiological factor in hyperdivergent patients
                                                                   9.
                                                                         1981; 80(1):92-7.
                                                                         Peng CL, Jost-Brinkmann PG, Yoshida N, Miethke RR, Lin
                                                                         CT. Differential diagnosis between infantile and mature swal-
                                                                         lowing with ultrasonography. Eur J Orthod. 2003; 25(5):
                                             iI
                                                                         451-6.
and in patients with a vertical growth tendency. However,
                                                                   10.   Proffit, WR. Equilibrium theory revisited: factors influencing
maxillary expansion therapy successfully modified the
                                                                         position of the teeth. Angle Orthod 1978; 48:175-186.
triangle, supporting the hypothesis that palatal expansion
                                           on

                                                                   11.   Okhiba T, Hanada K. Adaptive functional changes in the
can induce positive reconditioning of tongue posture and                 swallowing pattern of the tongue following expansion of the
function (14).                                                           maxillary dental arch in subjects with and without cleft palate.
Tongue posture improvement due to orthodontic maxillary                  Cleft Palate Craniofac J 1989; 26:21-30.
expansion was achieved in all three experimental groups            12.   Ricketts RM. The wisdom of the bioprogressive philosophy.
                                 i


of patients (i.e., normo-, hypo-, and hyperdivergent), all of            Semin Orthod 1998; 4:201-209.
                              iz


whom initially had skeletal class II malocclusion, mixed           13.   Gallerano G, Ruoppolo G, Silvestri A. Myofunctional and
dentition, and infantile swallowing, as revealed using                   speech rehabilitation after orthodontic-surgical treatment of
                                                                         dento-maxillofacial dysgnathia. Prog Orthod. 2012
cephalometric evaluation of the hyoid triangle before and
              Ed




                                                                         May;13(1):57-68.
after treatment. This treatment was especially successful          14.   Ozbek MM, Memikoglu UT, Altug-Atac AT, Lowe AA. Stabil-
among male, normodivergent, or hypodivergent patients                    ity of maxillary expansion and tongue posture. Angle Orthod.
aged between 6 and 7 years. However, further studies are                 2009 Mar;79(2):214-20.
 IC
C
©




Annali di Stomatologia 2012; III (3/4): 95-99                                                                                          99
