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Tongue volume in adults with skeletal Class III dentofacial deformities
Ihan Hren and Barbič Head & Face Medicine
Tongue volume in adults with skeletal Class III dentofacial deformities
N. Ihan Hren 0
U. Barbič 0
0 Department of Maxillofacial and Oral Surgery, University Medical Centre Ljubljana , Zaloška cesta 2, 1000 Ljubljana , Slovenia
Background: The size of the tongue is implicated as an essential etiological factor in the development of malocclusions. The aim of our study was to assess tongue size in skeletal Class III (SCIII) patients in comparison to adults with normal occlusion, using three-dimensional (3D) ultrasound. Methods: The SCIII group consisted of 54 subjects; 34 females and 20 males and the control group contained 36 subjects, 18 from each gender with Class I relationship. 3D ultrasound images of the tongues were acquired, and then the tongues' volumes were assessed. Results: The males in both the SCIII and control groups had significantly larger tongue volumes than the female subjects (mean SCIII 100.8 ± 6.3 and control 92.4 ± 9.8 cm3 in males vs. SCIII 77.4 ± 10.2 and control 67.2 ± 5.6 cm3 in females). The highly significantly larger tongue volumes were in SCIII patients of both genders (p were less than 0.01 for female and 0.03 for male). The tongue volumes within the whole SCIII group were significantly larger with more negative Wits values. Conclusion: The tongue volumes are significantly bigger in SCIII subjects than normal. Larger tongues correlate with more severe SCIII. The clinical importance of this data is that limited mandibular setback planning is necessary to prevent narrowing of respiratory airways.
Skeletal Class III; Tongue; Volume
Background
Skeletal class III (SCIII) better known as mandibular
prognathism in spite the fact that this term describes
only one form of this dentofacial deformity. It is a
severe dentofacial disharmony which frequently shows
combinations of skeletal and dentoalveolar
characteristics resulting in different facial appearances. The
common characteristic is changed anteroposterior
relationship between maxilla and mandible with their
changed sizes and positions in relation to the anterior
cranial base. The more common clinical sign of that is
Class III dental malocclusion.
The etiology of SCIII appears to be a result of
interactions amongst the genetically determined factors and
many internal and external environmental factors but the
precise roles of both have as yet to be clarified. Amongst
them traditionally the muscle equilibrium among intraoral
and buccal forces has been understood for the normal
development of dental arches but this simple theory was
revisited because any equilibrium between the force of the
tongue and the force of lips couldn’t be found [
1
].
It is hypothesised that the tongue volume, besides
posture and function, is of crucial importance in the
etiology of malocclusions and dentofacial deformities
[
2
]. Macroglossia and its consequences are well-known
in Beckwith-Wiedemann syndrome [
3
] and acromegaly
[
4
], it was suggested as a possible cause of open bite
and mandibular prognathism [
5
]. However the role of
tongue volume in mandibular prognathism was also
rejected [
6
]. The studies of tongue reductions have
reported about changing the skeletal Class III into Class I
in the early preadolescent period [
7
] and about dental arch
lingual collapse after a decrease in tongue volume [
8
].
Clinical studies have reported that tongue volume is
correlated with mandibular arch size [
9
], vertical facial
height, and chin position [
6
].
The dilemma is longstanding about tongue adaptation
to existing oral morphology or actively moulding its
surrounding tissues [
10, 11
]. So determining the size of the
tongue in different facial morphological variants and the
examination of other possible tongue roles such as
pressure, mobility, and rest postures are still to be clarified. It
has also been suggested that an increase in the volume of
soft tissues induces osteogenic reaction at the growth site
of the bone. With the relative increase of tongue volume,
which means a decreased volume of the oral cavity as
consequence of orthognathic surgical procedures with
normal volume of the tongue, the relapse can be explained
and indications for tongue reductions determined [12].
The aim of this study was to evaluate the tongue size at
its normative volume in SCIII patients in comparison to
patients with normal occlusion using three-dimensional
ultrasound as valid and non-invasive methods. Therefore,
the null hypothesis assumes that there is insignificant
correlation between the tongue volume and the
maxillamandibular relationship CIII.
Methods
The study was approved by the Ethics Committee of the
Republic of Slovenia, and informed consents were
obtained from all subjects involved in the study. The SCIII
group consisted of 54 subjects, 34 females (aged 25.5 ±
10.3 years) and 20 males (aged 21.5 ± 4.6 years), with Class
III molar relationships, negative overjet and skeletal
defo (...truncated)