39 Journal of Contemporary Orthodontics, Jan-March 2020;4(1):39-45

To cite: Sugandha

Namrata Massey, Rana

Pratap Maurya, Tripti

Tikku, Akhil Agarwal,

Kamna Srivastava,

Karunesh Tiwari

Tongue Pressure Exerted On

the Loop of Transpalatal

Arch in Different Craniofacial

Patterns

J Contemp Orthod 2020;4(1):

39-9.

Received on:

20-01-2020

Accepted on:

13-02-2020

Source of Support: Nil

Conflict of Interest: None

Tongue Pressure Exerted On the Loop of Transpalatal Arch

in Different Craniofacial Patterns

1Sugandha Namrata Massey, 2Rana Pratap Maurya, 3Tripti Tikku, 4Akhil

Agarwal, 5Kamna Srivastava, 6Karunesh Tiwari

1Ex-Post-Graduate Student, 2Reader, 3 Professor and Head of Department, 4Ex-Reader, 5Reader, 6Assistant

Professor

1-5Department of Orthodontics and Dentofacial Orthodontics

6Department of Physics , Babu Banarasi Das University Lucknow, U.P. India

1-5Babu Banarasi Das College of Dental Sciences, Babu Banarasi Das University Lucknow, U.P. India

ABSTRACT

Objective: To evaluate the tongue pressure exerted on the loop of transpalatal arch in different craniofacial patterns at different heights from the palatal mucosa.

Material and Method: 15 subjects were divided into three groups according to Schudy’s facial divergence angle as: Group I (Normodivergent), Group II (Hypodivergent) and Group III (Hyperdivergent). TPA was fabricated and placed at 2mm, 4mm and 6mm heights from the palatal mucosa in each subjects and tongue pressure was measured during swallowing using pressure sensors placed on the loop of TPA. The data obtained were recorded and subjected to statistical analysis.

Result: On intergroup comparison, maximum tongue pressure was found in Group III followed by Group I and Group II and the difference was statistically significant (p<0.001). When comparison was done at different heights tongue pressure was found highest at 6mm followed by 4mm and 2mm in each group and difference was statistically significant (p<0.001).

Conclusion: The maximum tongue pressure was observed in Hyperdivergent and minimum in Hypodivergent craniofacial pattern. It increases as the distance of the TPA from the palatal mucosa increases in all craniofacial patterns.

Keyword: Hyperdivergent; Hypodivergent; Normodivergent; Transpalatal Arch, Tongue pressure.

INTRODUCTION

Tongue posture and functions are of interest in regard to their

relationship to the malocclusions. The tongue affects the

dentition, alveolar bone and other supporting structures

during function as well as at rest. Tongue pressure during

swallowing has been found to be several times higher than

the lip or cheek pressures[1] Graber reported the average

frequency of deglutition to be once a minute between meals

and nine times a minute during eating.[2] Even during sleep the

swallowing act is performed at infrequent intervals. The

average frequency of deglutition is between 1,600-2,400

times a day.[3,4] Due to this high frequency of deglutition the

tongue pressure exerted is quite high and this pressure

experienced per deglutition can be utilized in correction of

malocclusions.

Investigators have measured the tongue pressure in order to

incorporate its useful effects in correction of various

malocclusions. Christiansen et al.[5] evaluated the average

force of the resting tongue as 0.8 gm (pressure = 0.039

g/mm2) when measured with a 4.9 mm diameter sensor.

Winders6 and Kydd et al.7 stated that the tongue pressure during

deglutition ranges from 41-709 g/cm2 (0.40-6.95 N/cm2) and

37-240 g/cm2 (0.36-2.35 N/cm2) respectively.

Transpalatal arches (TPA) are routinely used in orthodontic

treatment in both the permanent and mixed dentition. It can be

used to stabilize or reinforce the anchorage, or activated to

produce various types of tooth movement including derotation

of unilateral or bilateral rotated molars, correction of molar

crossbites, asymmetric or symmetric distalization of molars,

buccal or lingual root torque and molar intrusion.[8-11] TPA along

with headgear can also be given to correct the Class II

malocclusion in young adults with vertical growth pattern.[8]

Hata12 investigated tongue forces imparted to the palatal bar and

their control on vertical maxillary growth. Kazuhiro[13] et al

measured tongue pressure during swallowing and found

superiority of tongue pressure production at the antero-median

part of hard palate. Wise et al[14] studied the effects of a normal

transpalatal arch on vertical control of the maxillary first molars

Original Article

Rana Pratap Maurya et al

40

and found restricted eruption of the molars by 0.20 mm per

year. Chiba et al[15] measured the pressure of the tongue on the

transpalatal arch and found maximum pressure exerted at a

distance of 6mm from the palatal mucosa and when placed at

the level of the second molars. It was suggested that the

intrusion effect of TPA would be enhanced if its distance to

the palatal mucosa was increased or if its interactional area

with the tongue was augmented by adding an acrylic button

to the loop.

Figure 1: Clinical evaluation of patient’s facial divergence

The resting position of tongue is different in various

craniofacial patterns as well as in various malocclusions.

According to Wright et al[16] normal tongue posture is when

the apex of the tongue was slightly below the mandibular

incisal edges and the dorsum was visible above the teeth in

all parts of the mouth. It has been observed that in Class II

cases the position of the tongue is more backward and in

Class III cases more forward. According Subrahmanya and

Gupta[17] the dorsum of the tongue was found significantly

higher in vertical skeletal pattern at all the points. In

normodivergent facial pattern; the tongue rests at the

corrugated transverse ridges present on the palate and the tip

of the tongue behind the anterior teeth.

Figure 2: Placement of TPA with pressure sensors: (A)

Pressure sensors on the loop of TPA, (B) TPA along with

pressure sensors in the patient’s mouth.

Studies have been conducted on vertical control of maxillary

molars by utilization of tongue pressure exerted on the loop of

TPA in Class I molar relationship but no studies have been

performed till now in different craniofacial patterns. Since the

position of tongue varies in different craniofacial types,

therefore the pressure exerted by the tongue may also vary. This

pressure exerted by the tongue on the loop of transpalatal arch

can be utilized for control of molars in different facial types. So,

the purpose of this study was to measure the pressure of the

tongue exerted on the loop of the TPA during deglutition at

different vertical heights from the palatal mucosa in different

craniofacial patterns.

Figure 3: Recording of tongue pressure: (A) Projection of wire

from sensor placed in patient’s mouth, (B) Calibration of

amplifier at 0 with tongue not touching the sensor, (C) Reading

on amplifier during swallowing, (D) Amplifier recording tongue

pressure.

MATERIALS AND METHODS

Sample:

This study was conducted in the Department of Orthodontics

and Dentofacial Orthopaedics, Babu Banarasi Das College of

Dental Sciences, Lucknow. The sample for the study consisted

of 15 subjects, selected from the screening of 45 patients

coming to the department for orthodontic treatment. The

screening was done in two stages. In the first stage clinical

examination was done and in the second stage it was confirmed

by the analysis of lateral cephalogram. Approval from Ethical

Committee was obtained and written consent was taken from

each patients prior to conduct of this study.

Criteria for sample selection:

Inclusion Criteria:

41 Journal of Contemporary Orthodontics, Jan-March 2020;4(1):39-45

1. Good general health with good oral and periodontal

health.

2. Normal orofacial and tongue anatomy.

Exclusion Criteria:

1. Any history of systemic illness, pharyngeal pathology,

speech or deglutition problems.

2. Any facial asymmetry or syndrome affecting the

orofacial morphology.

3. Tongue abnormalities (macroglossia / microglossia) or

tongue-tie or abnormal tongue habits.

4. Enlarged tonsils, adenoid or nasal obstruction.

5. The subjects with neuro-muscular problems.

Methodology:

Method of Sample selection:

In clinical examination, estimation of facial divergence was

done using a metallic scale placed parallel to the Frankfort

horizontal plane and keeping another scale along the lower

border of mandible (Figure-1). Based on the results of

clinical examination, the craniofacial patterns of the selected

subjects were confirmed by cephalometric analysis according to

the values of Schudy’s facial divergence angle (SN-MP).

Selected 15 subjects were divided into three groups: Group I

(Normodivergent), Group II (Hypodivergent) and Group III

(Hyperdivergent). The tongue pressure was measured at three

different distances of 2, 4 and 6 mm between the loop of TPA

and palatal mucosa; thereby the groups were further named as

Group IA, IB and IC for Group I and similarly for the other

groups (Table-1).

Placement of TPA and pressure sensors in oral cavity:

The TPA was fabricated on the plaster model and the metal

sleeve with the pressure sensors were placed at the loop of the

TPA. Then whole assembly was transferred to the patient’s

mouth by inserted into the lingual sheath welded to the molar

bands (Figure-2). In order to minimize disturbance of the oral

muscles and any hindrance in the occlusion, the connecting

wires of the pressure sensors were passed distal to the last molar

through the vestibule and out of the oral cavity at the angle of

the mouth. The wire was connected to the battery operated

amplifier for pressure calibration.

Recording of tongue pressure:

A tongue pressure measuring assembly included, pressure

sensor based on the principle of strain gauge, a connector,

amplifier and recording device. Tongue pressure was measured

on digital amplifier connected to the sensors placed on the loop

of TPA. The recordings were done with the subjects sitting in

the upright position and head unsupported. The amplifier was

calibrated to zero before each measurement when the tongue

was not touching the sensors (Figure-3A and B). The subjects

were asked to swallow 5ml of water at room temperature to

minimize the influence of temperature change. The maximum

pressure for three swallowing at each position of the TPA was

recorded. During each swallowing, three maximum pressure

reading were recorded, thus a total of nine readings were

recorded for 3 swallowing at each position of TPA (Table-2) for

one of the samples. Out of these nine readings at each position

the mean was calculated and was used as the final value (Figure

Table 1: Distribution of sample

Group

Subgroup Distance from palatal mucosa

Group I (N=5)

(Normodivergent)

Group IA 2mm

Group IB 4mm

Group IC 6mm

Group II (N=5)

(Hypodivergent)

Group IA 2mm

Group IB 4mm

Group IC 6mm

Group III (N=5)

(Hyperdivergent)

Group IIIA 2mm

Group IIIB 4mm

Group IIIC 6mm

Table 2: Recording of tongue pressure for one of the

sample

Sample No. of

deglutition

Tongue pressure

(g/cm²)

1

1 172

170

171

2 173

172

174

3 173

174

175

Average tongue pressure

for sample 1 172±1.5

Rana Pratap Maurya et al

42

2 and 3). The same procedure was applied for all the

subjects.

STATISTICAL ANALYSIS

Categorical variables were presented in number and

percentage (%) and continuous variables were presented as

mean and SD. Quantitative variables were compared using

ANOVA between three groups and Scheffe’s Multiple

Comparison Test was used for intragroup comparison. The

statistical analysis was done using Statistical Package for

Social Sciences (SPSS) version 21.0.

RESULTS

Maximum tongue pressure was found in Group III, followed

by Group I and minimum for Group II. Tongue pressure was

found highest at 6mm followed by 4mm and lowest at 2mm in

each group. When intragroup comparison of tongue pressure in

various subgroups (at different heights from TPA to palatal

mucosa) using one way ANOVA test (Table-3) and Scheffe’s

test (Table-4) was done, statistically significant difference

(p<0.001) was seen amongst the subgroups of all the Groups.

Intergroup comparison using Scheffe’s test (Table-5) at

different heights also showed a statistically significant

(p<0.001) for various subgroups.

DISCUSSION

Oral functions such as mastication, deglutition, speech and

Table 3: Intragroup comparison of tongue pressure exerted on the loop of TPA placed at different heights (ANOVA test)

Group No. of

samples

(N)

Tongue

pressure

(g/cm²)

Standard

Deviation

95% Confidence Interval for Mean ‘p’ value

Lower Bound

(g/cm²)

Upper Bound

(g/cm²)

Group I-A (2mm) 5 171.20 0.84 170.16 172.24 <0.001****

Group I-B (4mm) 5 231.40 1.14 229.98 232.82

Group I-C (6mm) 5 334.20 1.10 332.84 335.56

Group II-A (2mm) 5 141.80 0.84 140.76 142.84 <0.001****

Group II-B (4mm) 5 209.60 2.70 206.25 212.95

Group II-C (6mm) 5 319.60 0.89 318.49 320.71

Group III-A (2mm) 5 273.20 1.30 271.58 274.82 <0.001****

Group III-B (4mm) 5 302.20 2.17 299.51 304.89

Group III-C (6mm) 5 372.80 1.30 371.18 374.42

p≤0.001=highly significant٭٭٭٭

Table 4: Intragroup comparison of tongue pressure on the loop of TPA placed at different heights (Scheffe’s test)

Group I(Normodivergent) Group II (Hypordivergent) Group III (Hyperdivergent)

Group Mean

difference in

tongue

pressure

(g/cm²)

‘p’

value

Group Mean difference

in tongue

pressure (g/cm²)

‘p’

value

Group Mean difference

in tongue pressure

(g/cm²)

‘p’ value

Group

IA vs

IB

60.200 <0.00

1

٭٭٭٭

Group

IIA vs

IIB

67.800 <0.00

1

٭٭٭٭

Group IIIA

vs IIIB

٭٭٭٭0.001> 29.000

Group

IA vs

IC

163.000 <0.001

٭٭٭٭

Group IIA vs

IIC

177.800 <0.001

٭٭٭٭

Group IIIA vs IIIC

٭٭٭٭0.001> 99.600

Group

IB vs

IC

102.800 <0.00

1

٭٭٭٭

Group

IIB vs

IIC

110.000 <0.00

1

٭٭٭٭

Group IIIB

vs IIIC

٭٭٭٭0.001> 70.600

p≤0.001=highly significant٭٭٭٭

43 Journal of Contemporary Orthodontics, Jan-March 2020;4(1):39-45

respiration plays an important role in the growth and

development of the maxillofacial region. The posture and

function of tongue is of significance in the expression of any

malocclusion. Bobak[18] et al conducted a FEM study and

suggested that TPA increases molar displacement and

controls molar rotation. Various studies[6,14,15,19-24] suggested

that tongue pressure was higher in posterior region and the

intrusion effect of the TPA would be enhanced if its distance

from the palatal mucosa increased. The resting tongue

position varies in different craniofacial patterns and is higher

in vertical skeletal pattern.

The results of the present study demonstrated that the tongue

pressure on the loop of TPA showed statistically significant

difference in various craniofacial patterns and at different

heights from palatal mucosa. These findings can be

interpreted in the light of stages of deglutition, which is the

most important function of stomatognathic system. Before

deglutition, the food bolus is sucked into the mouth by

withdrawing the tongue from front to back. Deglutition

begins by increasing the palatal contact of tongue from front

to back and tongue is lowered in same sequence. Thus the

base of the tongue is moved forcibly upward and backward

towards hard palate, sweeping the food backward down the

pharynx. This kind of tongue movement creates a

considerable force on hard palate, alveolar ridge and any

dental appliance positioned in its way during swallowing.

This is the reason that considerable amount of tongue

pressure was observed in different craniofacial pattern at

different heights of TPA in the present study and this in turn

can be used clinically for vertical control of molars.

The effect of TPA had been evaluated previously either by

assessing mechanical effects of TPA14,19,25 or by measuring

tongue pressure in healthy or normal subjects during repeated

swallowing of their own saliva or during swallowing of water

or during mastication of gummy jelly6,13,15,21,22,24 or in

subjects with malocclusion like open bite[26] during swallowing

of saliva and water, but none of the studies had evaluated

variability in tongue pressure in different craniofacial patterns.

Wise et al[14] found that the mean molar extrusion was 0.2mm

lesser in TPA wearing group for a period of 5 months than the

group without TPA throughout the treatment. They also

suggested that the intrusion effect of the TPA would be

enhanced if its distance to the palatal mucosa was increased. De

Berardinis et al19 used a modified TPA to evaluate the molar

intrusion effect of TPA by adding an acrylic plate and named it

a vertical holding appliance (VHA). They found that the VHA

is useful in restricting vertical dimension by preventing molar

extrusion and helps in reducing the percentage of lower anterior

vertical face height. Along with intrusion, Nanda25 described the

distal movement of maxillary molars with the use of VHA in

Class II patients. Utanohara et al21 found that the tongue

pressure decreased with age as a result of an age-related

reduction in muscle mass.

Kennedy et al22 measured tongue pressure by placing pressure

transducers at three locations of palate in Angle’s Class I molar

relation patients during water swallowing and found maximum

pressure (15 kPa) at mid-palatal region. As this position is

comparable with the position of the loop of TPA in our study,

we can say that the results of their study were consistent with

our study. In our study also, the tongue pressure was found to be

ranging from 13-16 kPa when the loop was closest to the palate

in normodivergent and hypodivergent subjects. On the contrary

the tongue pressure for hyperdivergent subjects was higher

(26kPa). This difference may be due to the fact that their small

sample size of 6 subjects which might not be having any

subjects with Hyperdivergent growth pattern. Hori et al13

observed more tongue pressure at the anterior part than at the

middle or posterior part on the median line, on the habitual

masticatory side and in the later stages of mastication just at the

beginning of initial swallow. According to the authors, close

Table 5: Intergroup comparison of tongue pressures on the loop of TPA at various heights (Scheffe’s test)

2mm distance from the palatal

mucosa 4mm distance from the palatal

mucosa

6mm distance from the palatal mucosa

Group Mean

difference

in tongue

pressure

(g/cm²)

‘p’

value

Group Mean

difference

in tongue

pressure

(g/cm²)

‘p’

value

Group Mean

difference in

tongue

pressure

(g/cm²)

‘p’ value

Group

IA vs

IIA

29.400 <0.001 ٭٭٭٭

Group IB vs IIB

21.800 <0.001 ٭٭٭٭

Group IC vs IIC

٭٭٭٭0.001> 14.600

Group

IA vs

IIIA

102.000 <0.001

٭٭٭٭

Group IB

vs IIIB

70.800 <0.001

٭٭٭٭

Group IC

vs IIIC

٭٭٭٭0.001> 38.600

Group

IIA vs

IIIA

131.400 <0.001

٭٭٭٭

Group

IIB vs

IIIB

92.600 <0.001

٭٭٭٭

Group

IIC vs

IIIC

٭٭٭٭0.001> 53.200

p≤0.001=highly significant٭٭٭٭

Rana Pratap Maurya et al

44

contact of tongue with hard palate during late stage of

mastication or beginning of initial swallow results in

increased tongue pressure. The position of the sensor could

be compared to sensor placed on loop of TPA in our study.

But the pressure was 5.6kPa in their study whereas it was 13-

26 kPa in our study. The difference in the value can be

attributed to the intervening acrylic plate in their study

whereas pressure was directly measured at sensor placed on

the loop in our study. Another reason could be that we asked

the patient to complete the act of swallowing of water

whereas they measured tongue pressure only till the

beginning of initial swallow.

Xu et al24 observed that the tongue pressure was increased

when distance from modified TPA was increased from palate

and suggested that higher tongue pressure in vertical growers

is expected. Similar findings were obtained in our study

where the tongue pressure was higher in vertical growth

pattern and pressure was increased when the distance of the

loop from the palatal mucosa was increased. Therefore for

effective molar intrusion in vertical growers we can place

TPA at a higher level from the palate. Chiba et al15 found

maximum tongue pressure on the TPA at the second molars

level and it was increases as the distance from TPA to palatal

mucosa increases except in first molar region. They

suggested that tongue contact with the palate increases from

the front to the back leading to higher values of tongue

pressure in the second molar.

Findings of our study help in modifying the usage of TPA in

various craniofacial patterns. Considering the tolerance limit

of an individual, TPA can be used at increased height from

the palatal mucosa for effective molar intrusion in vertical

growers. It can also be used effectively at lesser heights in

vertical growers for vertical anchorage control as the tongue

pressure experienced on the loop of TPA is higher even at

lesser heights when compared with other growth patterns. On

contrary, in adult subjects with Normodivergent or

Hypodivergent pattern where molar extrusion occurs because

of different orthodontic mechanics like intrusion arches or

loop mechanics for space closure need to be prevented, TPA

at variable heights can be used as per the requirement of

particular case.

In future, further scope of the study is to measure the tongue

pressure in greater number subjects with various types of

malocclusions as well as in different craniofacial patterns by

adding acrylic button on loop of TPA. Also, the role of

tongue pressure in subjects with various defects such as Cleft

of lip and palate can be evaluated.

CONCLUSION

The maximum tongue pressure exerted on the loop of TPA

was observed in Hyperdivergent, followed by

Normodivergent and minimum in Hypodivergent

craniofacial pattern.

As the distance from the palatal mucosa to the loop of TPA

increases, tongue pressure increases in all the craniofacial

types.

For effective vertical control of molars, TPA can be used at

greater distance from the palatal mucosa.

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