Assessment of tongue posture in class I malocclusion with vertical malrelations

Ahmed M Al-Shennawy; Atia A. E. W. Yousif; Neven F Abo Taha

doi:10.4103/tdj.tdj_39_22

ORIGINAL ARTICLE

Year : 2023 | Volume : 20 | Issue : 2 | Page : 105-110

Assessment of tongue posture in class I malocclusion with vertical malrelations

Ahmed M Al-Shennawy M.SC. , Atia A. E. W. Yousif, Neven F Abo Taha
Department of Orthodontics, Faculty of Dentistry, Tanta University, Tanta, Egypt

Date of Submission	02-Sep-2022
Date of Decision	18-Nov-2022
Date of Acceptance	19-Nov-2022
Date of Web Publication	11-May-2023

Correspondence Address:
Ahmed M Al-Shennawy
Dentist, 70, Said St., Tanta, Gharbia
Egypt

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/tdj.tdj_39_22

Abstract

Introduction
Tongue is a soft muscular tissue which is mainly made of mucosa, muscles, vascular and nerve supply. The mucosa of body is formed from the first pharyngeal arch and third pharyngeal arches; while the skeletal muscles develop from myoblast that migrate from occipital somite's.
Aim
Owing to its effect on the building structures all around and vital functions, this study was carried out to assess the tongue posture in vertical malrelations; in class I malocclusion.
Materials and methods
A cephalometric study was carried out on 153 adult patients (76 female, 75 male) from 17 to 22 years old) with skeletal class I. The sample was selected according to the mandibular plane angle (SN/GO-GN) and categorized according to vertical facial pattern into; high angle (SN/MP >37), low angle (SN/MP <27) and average angle (SN/MP 32 ± 5°); including 26 females and 25 males in each group. The tongue position was calculated along horizontal line passing through the incisal edge of the lower central incisor to the cervical distal third of the lower second molar and extending posteriorly. Taking the cervical area as a center, six angles will be drawn at 0°, 30°, 60°, 90°, 12°, and 150°. The contours of the dorsum of the tongue and the palate and six distances will be measured at 0°, 30°, 60°, 90°, 120°, and 150° between tongue and palate contour.
Results
Tongue positions were found to be higher in position in skeletal class I malocclusion in low and high mandibular plane (posterior part of the tongue); on the other, lower tongue position (anterior part) was found in increased mandibular plane angle without sex differences
Conclusion
Tongue position is affected by the position of the mandible in vertical plane; regarding the anterior or posterior part without sex differences.

Keywords: class I vertical malrelations, tongue posture, vertical facial reights

How to cite this article:
Al-Shennawy AM, Yousif AA, Abo Taha NF. Assessment of tongue posture in class I malocclusion with vertical malrelations. Tanta Dent J 2023;20:105-10

How to cite this URL:
Al-Shennawy AM, Yousif AA, Abo Taha NF. Assessment of tongue posture in class I malocclusion with vertical malrelations. Tanta Dent J [serial online] 2023 [cited 2023 May 28];20:105-10. Available from: http://www.tmj.eg.net/text.asp?2023/20/2/105/376637

Introduction

The position of the tongue at rest is thought to have a stronger influence on the position of teeth than the pressure exerted by perioral soft tissues mostly in short term. The space necessary to accommodate the tongue towards the roof of the palate in cases of severe maxillary constriction has been proven to be insufficient, and tongue posture is lower than optimal ^{[1],[2],[3],[4],[5]}.

The tongue, in both humans and animals, has long been regarded as a complex organ. One of the five senses is included within this highly specialized mix of muscles and nerves. It is capable of a tremendous deal of mobility, Takada et al. ^[6] investigated the relationship between the tongue volume and the capacity of the oral cavity proper, hypothesizing that changes in the level of the mouth's floor, which are likely reflected in the position of the tongue, balance the capacity of the oral cavity and the tongue volume-column of the hyoid-larynx.

Lowe et al. ^[7], conducted a study of 60 adult females with normal and anterior open-bite (AOB) malocclusions. The first canonical correlation (r = 0.962) represented a size-related correlation factor between the two groups of variables. Patients with characteristics of a short face syndrome and some evidence of overbite had tongue tips positioned below the lower occlusal plane (r = 0.929). In contrast, skeletal open-bite patients (r = 0.759) revealed tongue tips ahead of and above the lower incisor teeth with the mandible in the rest position. Unerupted mandibular teeth (r = 0.666) were associated with a reduced tongue height and an inferior epiglottis; short tongue length (r = 0.563) correlated with a linear combination of upright central incisors, a small overjet, a low ANB angle, unerupted maxillary and mandibular teeth, and a steep occlusal plane. The multivariate statistical analysis extracted clinically significant associations between tongue soft-tissue and dentoskeletal variables. Tongue posture at rest in skeletal open-bite patients appeared to be related to incisor position.

The rest position, defined as 'the position of the mandible when the patient is in the upright position and the muscles controlling the position of the mandible are in relaxed equilibrium' in The Glossary of Prosthetic Terms (Academy of Dental Prosthetics, 1977) ^[8], has been the patient of much debate, with opinions varying as to whether it is affected by the presence or absence of teeth.

The etiology of bimaxillary proclination has been linked to a variety of factors, including tongue size and posture. Understanding the mechanism of certain types of malocclusions and objectively quantifying the effects of various surgical and/or orthodontic treatments requires an understanding of the interplay between tongue size and volume and cranial skeletal growth ^[9].

Variations in resting lip and tongue pressures and their link to alterations in head posture in class I and class II were investigated by Archer and Vig ^[10] in 1985. Pressures were measured in a natural head position with 20° of head extension and 20° of head flexion in 10 class I and 11 class II participants. In all head positions, posterior lingual pressures differed from labial pressures in class I participants. The posterior lingual pressures in class II patients differed from labial pressures in flexion and natural head postures, as well as anterior lingual pressures in flexion and natural head positions. With head extension, there was no rise in labial pressures.

Moreover, a study was conducted by Kim and Lee ^[11] to investigate the relationship between posture, tongue size, and dentoalveolar pattern. The lengths, heights, and areas of the tongue and intermaxillary space, were measured on cephalograms. Bimaxillary protrusion had the longest tongue length, followed by normal occlusion and class III malocclusion. In class III malocclusion, tongue posture was the lowest, followed by bimaxillary protrusion and normal occlusion.

Primozic et al. ^[12] used cast analysis and cephalometric radiograph to analyses tongue position in class I and class III on 40 patients divided into two groups: class I (six males, 14 females) and class III (nine males, 11 females) ranging in age from 17 to 19 years. Tongue posture is much lower in class III patients and is linked to the maxilla and mandible's dentoalveolar features.

Vald et al. ^[13] studied the position of the tongue and the activation of the temporalis and masseter muscles in 33 students (21 women and 12 men) aged 18–22. The results of EMG with two positions of the tongue, one on the anterior hard palate and one on the floor of the mouth, were recorded for each tongue position. Although there was no significant difference in EMG activity for either the masseter, temporalis muscle or the tongue between the two tongue positions, there was a significant difference in VD as a result of the two tongue positions, with the VD being greater with the tongue in the floor of the mouth.

In 2015, Kadhum ^[14] 30 patient was selected (15 males, 15 females) with ages ranging from 23 to 24 years old were selected. Patients with a class 1 dental and skeletal pattern who did not have a history of sleeping disorders had a cephalometric radiograph taken to determine the length and height of the tongue, as well as the position of the hyoid bone from the cervical lines. The male values were significantly different from the female values.

In another study of Cristina et al. ^[15], studied the location of tongue and lips in participants of 54 children with age from 7 to 11 years old using cephalometric radiograph. The typical tongue position was defined as in the papilla, high dorsum, or on the floor of the mouth, whereas the typical lips posture was classified as closed, half-open/open. The SNB angle was found to have a statistically significant connection with tongue position; children with tongue position on the floor of the mouth had a considerably lower SNB angle than children with tongue position in the papilla. The angle of the SNB was statistically significant.

Sucking, chewing, breathing and speaking, all need the use of the tongue. Oro-facial functioning and tooth alignment are disrupted when its posture is abnormal. So, Mauclairea et al. ^[16] determined the functional effects of the tongue right positioner on lingual posture as well as the velo-pharyngo-lingual system in orthodontic patients.

Tarkar et al. ^[2],[17] measured the upper and lower pharyngeal airway dimensions in 90 participants aged 18–32 years old, dividing them into three groups: group I (n = 30; average growth pattern), group II (n = 30; horizontal growth pattern), and group III (n = 30; vertical growth pattern). They found substantial difference in the position of the tongue's dorsum in the vertical growth pattern.

Kravanja et al. ^[9] investigated the link between inappropriate tongue posture, articulation problem, and the etiology of open bite. There were 32 children with an AOB and 43 children with normal occlusion. In terms of inappropriate tongue posture (P = 0.001) and articulation abnormalities (P = 0.001), the AOB group and the control group were significantly different. The inappropriate tongue posture occurred less frequently in children without articulation issues from both groups than in children with articulation abnormalities (P = 0.001).

Fatima and Fida ^[18] studied tongue posture in 90 people using cephalograms and casts, then divided them into three groups according to class I, class II, and class III, as well as the distinction between the tongue and the palate, and discovered a significant difference in inter-canine and inter-molar width.

Gonzalez et al. ^[19] studied tongue position during deglutition in children aged 8–16 years with an AOB and typical vertical overbite (NVO). This study comprised a total of 132 children with AOB and 132 children with NVO. The difference in tongue contacts was measured in both groups, and a link between tongue position and anterior occlusion was discovered. During the oral phase, roughly 28.8% of AOB participants had tongue contact on the palatal surface of the incisors, compared to 13.6% of NVO participants.

Afzal and Fida ^[20] conducted a study to evaluate the change in the tongue posture and in the hyoid bone position after TBA therapy. Cross-sectional study was conducted using the prefunctional (PF1), postfunctional (PF2) and posttreatment (PT) cephalograms of 30 growing patients. The tongue posture at six distances and the hyoid bone position with four parameters were digitally measured. The comparison of the PF1 and PF2 values showed significant differences in the tongue posture at distances 1–5 cm.

Materials and methods

A cross-sectional study design was carried out on 153 male and female patients selected from the record in Department of Orthodontics, Faculty of Dentistry, Tanta University, Egypt

Inclusion criteria:

Normal nasal breathing.
Class I malocclusion (ANB 2–4°).
No abnormal habits.

Exclusion criteria:

Any craniofacial or dental anomalies.
Any previous orthodontic intervention.
Any pathological problems effecting either teeth or jaws.
History of trauma or surgery of the tongue or oral musculature.
Any deglutition disorders.

The sample size was calculate at n = 51 sampleineach group with power of study 80% andthe collected sample was allocated in three categories according to the mandibular plane angle [the angle between the anterior cranial base (SN) and the mandibular plane (GO-GN)] with age ranging from 17 to 22 years old.

Each group was further divided into male and female subgroup.

Group I: the average vertical facial pattern subgroup: 51 cephalometric radiograph (26 female and 25 male) with SN-MP 32 ± 5° [Figure 1].
Group II: the high angle vertical facial pattern subgroup: 51 cephalometric radiograph (26 female and 25 male) with SN-MP more than 37° [Figure 2].
Group III: the low angle vertical facial pattern subgroup: 51 cephalometric radiograph (26 female and 25 male) with SN-MP less than 27° [Figure 3].

Figure 1: Lateral cephalometric film of average angle case with SN-MP 32 ± 5°.

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Figure 2: Lateral cephalometric film of high angle case with SN-MP more than 37°.

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Figure 3: Lateral cephalometric film of low angle case with SN-MP less than 27°.

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Assessment of tongue posture

Tongue posture was assessed on the lateral cephalogram using the method described by Graber et al. ^[21]. A template with an inscribed millimeter scale will be used to assess the tongue position relative to the palate. The template will be drawn on the lateral cephalogram with its horizontal line passing through the incisal edge of the lower central incisor to the cervical distal third of the lower second molar and extending posteriorly. Taking the cervical area as a center, six angles will be drawn at 0°, 30°, 60°, 90°, 120°, and 150°. The contours of the dorsum of the tongue and the palate and six distances will be measured at 0°, 30°, 60°, 90°, 120°, and 150° between tongue and palate contour [Figure 4] ^[21].

Figure 4: Diagram of tongue position measurements.

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Statistical analysis

The collected data were classified into two groups according to sex (male and female). And further divided into three sub-groups (average, high and low) according to SN-MP angle. The obtained data were tabulated and statistically analyzed using analysis of variance (ANOVA) test using SPSS package, version 25.

Results

ANOVA test was used to determine the statistically significance differences between the means of the three variance of the vertical malrelations and tongue the cephalometric analysis of tongue positions [Table 1].

Table 1 Analysis of variance test for the cephalometric analyses in between groups of class I malocclusion

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In male and female, the result of this study showed a statistically significant differences between average and high SN/MP and high and low distance in D1 variable. Its logic to find a statistically significant difference between high and low angle which is determined by position of the mandible. In male and female patient cephalometric radiograph the tongue position assessment at, the length of D2 showed decrease than average in low and high SP/MP angle. At the same time in D 90° inclination decrease of the distance than average in male and female.

Discussion

It has been settled that, the forces exerted by perioral muscles and the tongue during its functions are play a very important role for guidance of tooth eruption and arch form.

In wards, to reach a normal arch form and accepted tooth alignment with balanced occlusion, the force exerted on the skeletal and dental arch during growth and development either form inside or outer side should be in balance (concept of equilibrium of the labio-lingual muscular force). The setting positions of the tongue which is greatly affected by vertical height either anterior or posterior supposed to have a direct effect on this force balance ^[21].

Owing to difficult in some radiograph for identification of Porion and Orbitali points (FH plane), SN plane considered logic with mandibular plane to assess and classify class I malocclusion into class I with average, low, and high mandibular plane angles ^[22].

The sample selected for this study included 153 cephalometric radiograph which were selected in relevance of criteria of skeletal class I malocclusion. They were classified into three groups according to mandibular plane angle into: average, low, and high angles. Multifactorial ANOVA was used to determine the statistically significant differences between variance.

Tongue posture in different (average, high and low SN/MP angle) vertical verities of skeletal class I malocclusion (types of mandibular plane angle) were determined in terms tongue to palate distance at predetermined six different points. DI is 0° graded to D6 on 30°, 60°, 90°, 120°, and 150° angle centered on the cervical distal third of lower second molar extending posteriorly ^[21].

In female patient, the result of this study showed a statistically significant differences between average and high SN/MP and high and low distance in D1 variable. This result may be attributed to the position and rotation of the mandible in increased SN/MP angle. Its logic to find a statistically significant difference between high and low angle which is determined by position of the mandible. Also, the same result was found in male patient with no difference between males and females patients. This finding is highly coincided with Graber et al. ^[21] who found the same result and Lowe et al. ^[7] who found that the tongue get posterior position of the in cases with increased anterior facial height.

In males and female patient enrolled in this study the posterior part of the tongue (the length of D2) showed decrease than average in low and high SP/MP cases. This may be attributed to posterior position of the tongue and canting of the palate posteriorly and the statistically significant difference between high and low SN/MP angle was due to steepness of the mandible. This result is agreement with that of Winder ^[23], and Garber who explain the effect of tongue pressure on the palate.

Also, the result of this study showed a decrease than average of the distance measured from the defined point on lower second molar on 60° inclination to the palate in high and low SN/MP angle while in male showed decrease in high angle only although sill there a statistically significant difference between high and low angle. This may be attributed to the size of the tongue or growth deficiency of the midface or level of the mouth floor. It relatively agrees with the finding of Takada et al. ^[6] who found an effect of the mouth floor the capacity of the oral cavity and hence on tongue position

The result of this study showed a decrease in D4 90 distance in male and female which is attributed to the geographic shape of the tongue it coincides with the result of Kim and Lee ^[11].

The relationship of the palate shape and the geographic shape of the tongue dorsum are clear on evaluation of the result derived from this study in D5 variable. Although the measurement was restricted more anteriorly on the tongue body, in either male or female patients. The condition is clearer on investigating the distance of D6, which is more anteriorly and the tongue is more affected by lips, way of swallowing, speech, and other functions.

Really, the tongue in both animal and human is considered complex organ. It is highly specialized combination of muscle and nerves. Many studied revealed that the tongue maintains a constant position for an existing occlusion and occupy at rest a lag part of oral cavity. Some abnormal habit like thumb sucking and abnormal swallowing may affect or change tongue position and destruct the line of occlusion producing malocclusion that is why the aim of this study was analyzed the tongue position in malocclusion.

Conclusion

Tongue positions were found to be higher in position in skeletal class I malocclusion in low and high mandibular plane.

Lower tongue position (anterior area) was found in increases mandibular plane angle in skeletal class I malocclusion.

Rotational position of the mandible has a direct effect on tongue position.

Financial support and sponsorship

Nil.

Conflicts of interest

None declared.

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