Orofacial Myofunctional Disorders in Children with Asymmetry of the Posture and Locomotion Apparatus

Abstract

352 children radiologically identified with asymmetry in the occipito-cervical region were assessed on a number of myofunctional measures. In all children an orthopedic examination was conducted including a functional test of the upper cervical spine and the iliac joint, the postural test by Matthiass, as well as gait analysis. During a second examination the orofacial myofunctional status was recorded. In general, about 70% of the children revealed orofacial myofunctional disorders. Correlational analysis was conducted in order to determine whether specific myofunctional variables were associated with postural and orthopedic alterations. A weak body posture correlated statistically significantly with all assessed myofunctional variables. On the other hand, all orthopedic items correlated significantly with a reclined head position. A blockade of the iliac spine correlated significantly with persistent habits, articulation disorders and tongue dysfunction, whereas functional asymmetry of the upper cervical spine correlated significantly with incompetent lips. A finding of at least five statistically significant correlations within each orofacial variable underlined the complex symptomatology of myofunctional disorders, so that consideration needs to be given to adequate treatment approaches. The data generated by the present study stress the importance of early interdisciplinary screening in children to ensure a physiological development of the orofacial region and the still growing vertebral column. To help understand the complexity of symptoms influencing orofacial development, an explanatory model of the “interactive functional box system” is given.

NTRODUCTION

A fundamental understanding of the mechanisms contributing to physiological craniofacial development is essential for the diagnosis and successful treatment of skeletal and functional impairments in the masticatory system and adjoining structures. A relapse of certain orthodontic treatment results alerts the orthodontist to focus not only on hard tissue structures such as teeth and jaws, but also, on the adjoining soft tissue structures and the function of orofacial muscles and tongue in order to achieve long-term stability. Clinical experience has shown that ignorance of persistent orofacial disorders often results in relapse. As demonstrated in various studies, the position of teeth may be affected by myofunctional therapy (Benkert, 1997; Garetto, 2001; Meyer, 2000).

Many practitioners have become aware of the complex pathology in children being referred for myofunctional therapy (Meyer, 2000). While abnormal swallowing used to be seen as the key dysfunction, increasing numbers of studies on this issue have focused attention on other dysfunctions such as mouth breathing (Marchesan and Huberman-Krakauer, 1996; Schievano, Rontani and Berzin 1999; Pierce, 1983), mastication and articulation disorders (Bigenzahn, Fischman and Mayrhofer-Krammel, 1992; Pierce, 1996; Umberger and Johnston, 1997). Moreover, recent scientific investigations have highlighted postural changes as an issue to be discussed in the field of myofunctional therapy (Huggare and Tellero Laine-Alava, 1997; Huberman-Krakauer and Guilherme, 2000; Marchesan, 2000).

Despite these observations, documentation often remains anecdotal and important questions are left unanswered: Does a statistically significant relation between changes in the hard tissue in the occipito-cervical region and soft tissue structures in the orofacial region exist? If so, which impairment has most impact on impeded orofacial development? The objective of the present research work was to provide answers to those questions and to evaluate the data in terms of possible preventive treatment approaches.

MATERIALS AND METHODS

Children with postural impairments and abnormalities of gait and balance were referred to the Center for Manual medicine. The present study was based on the data of 352 children aged 1-19 years (mean age 7.52 years  2.95 years). Inclusion criteria were the orthopedic and radiological diagnostic records recording suspected asymmetry of the upper cervical spine. Exclusion criteria were acute inflammatory, neurological and tumor-like affections, syndromes and radiologically proven inclination of the cervical spine, especially of the upper cervical spine. Young patients with structural orthopedic diseases, general medical diseases with long-term therapy, syndromes and physical or mental handicaps were also excluded. The orthopedic examination of the 238 boys and 114 girls was conducted by one manual therapist at the Center for Manual Medicine, whereas orofacial development was assessed by one orthodontist at the Department of Orthodontics at the University of Hamburg.

The data presented in this paper focus on the following variables:

Orthopedic records

Body posture and function of the cervical spine were evaluated with the child standing and bending forward in order to assess a scoliotic posture, thoracic and lumbar curvatures as an asymmetry of the spinal profile. The mobility of the head and neck was recorded with the patient sitting and the manual therapist standing behind. With a specially developed measuring technique the isolated head motion in anteflexion and rotation was measured (Koch, Korbmacher and Kahl-Nieke, 2003). Functional asymmetry was diagnosed with a side deviation in anteflexion and rotation of the head by more than 10° (Koch, Korbmacher and Kahl-Nieke, 2003). A standardized examination was carried out to determine the position of the pelvis by palpating the lateral iliac crest to check for the presence of an oblique pelvis and functional leg shortness.

A postural test proposed by Matthiass (1966) was used to verify the efficiency of the supporting spinal muscles. For this purpose the subject stretched both hands out to the front at right angles. In children who could not stay in that position for at least 30 seconds a hypotonic posture was recorded.

The radiological evaluation was conducted in two planes: a lateral x-ray and an anterior- posterior x-ray of the vertebral column (Gutmann, 1981). All children revealed a radiologically proven asymmetry or rotation of the upper cervical spine.

Orofacial myofunctional findings

The clinical examination of the orofacial status was carried out with the help of a standardized diagnostic evaluation form for patients with orofacial dysfunctions (Korbmacher and Kahl- Nieke, 2001. Standardized extraoral and intraoral clinical photos were taken for documentation purposes.

• Open mouth rest posture

Open mouth posture was assessed during the waiting period of more than five minutes (when the children were unaware of being observed). Signs of habitual mouth breathing such as cracks at the corner of the mouth were also recorded. The findings were supplemented by questioning both the parents and the children on mouth rest posture during the day and at night.

• Tongue dysfunction

The diagnosis “tongue dysfunction” consisted of two parameters: abnormal tongue position at rest and abnormal swallowing pattern. The latter was confirmed by palatography. After application of a paste to the tip and lateral edges of the tongue, the patient was asked to swallow. The color impressions were rated visually.

• Incompetence of lips

The observation included evaluation of the upper and lower lip lengths, the shape and competence of the upper lip at rest, and the mobility of the lips during speech and swallowing.

• Habit history

With the help of a standardized diagnostic form the parents and the children themselves were asked about negative oral habits such as sucking habits or nail biting. If questions on a former sucking habit were confirmed (i.e. the sucking habit was no longer persistent on the day of the examination but had lasted beyond five years of age) the habit history was marked as positive.

• Articulation disorders

Within the scope of a conventional diagnosis, irregular /s/ sound formation and articulation of the phonemes l, n, t, and d was rated.

• Reclined head position

The head position was assessed with the subject standing with the heels placed together and the arms hanging down. The self-balance position of the head will normally be achieved in young children without any special instructions. Older and more anxious children may be instructed to find this position by tilting the head slightly up and down with a decreasing amplitude and then finding the most comfortable position in between (Solow and Sandham, 2002). Special attention was paid to the position of the shoulders.

Statistical analysis

Statistical analysis was performed with SPSS^® 10.0 for Windows (Lead Technologies, Haddonfield, NJ, USA). In the calculation of correlations, the chi-square test according to Pearson was employed to test for any dependence between the myofunctional, orthodontic and orthopedic items. Fisher’s exact test was used for 2x2 tables if a table contained a cell with a predicted frequency of less than 5. The significance level was set at p<0.05.

RESULTS

Orthopedic findings

Functional asymmetry of the upper cervical spine was found in 68.8% (n=242) of the children. 60.8% (n=214) revealed functional asymmetry in the iliac joint. A weak body posture was found in 60.5% (n=213). An overview of the four orthopedic items is given in Figure 1.

Orofacial myofunctional disorders

In 71% (n=250) of the examined children at least two of the following orofacial variables were recorded: 55.7% (n=196) revealed open mouth rest posture; 71.9% (n=253) had an abnormal rest position of the tongue; 61.6% (n=217) had frontal tongue thrust and a tongue sucking habit. In 63.6% (n=224) a visceral swallowing modus was found. For the correlational analysis the diagnosis “visceral swallowing pattern” [tongue thrust] was determined. Since all infants exhibit a tongue thrust swallow pattern up to the age of five years, the diagnosis of tongue thrust was combined with abnormal rest position in children aged less than five years.

In 91.5% (n=322) the lips were incompetent at rest. 44.3% (n=156) revealed a sucking or chewing habit of the lips.

At the time of examination, habits such as thumb sucking or nail-biting were persistent in 64.5% (n=227) of the children. 59.4% (n=209) had a history of negative oral habits, which were no longer persistent at the time of examination. 63.6% (n=224) revealed articulation disorders of /s/l/n/t/d/. All myofunctional variables are summarized in Figure 2.

Correlations between myofunctional disorders and orthopedic findings

All recorded orofacial dysfunctions correlated statistically significant with a weak body posture. The reclined head position correlated significantly with all investigated orthopedic disorders. A blockade in the iliac spine correlated significantly with tongue dysfunction (p=0.017), with articulation disorders (p=0.02), and with persistent habits (p=0.019). Pathologies in the upper cervical spine correlated significantly with incompetent lips (p=0.021). For detailed information see

Table 1. Statistical correlations (highly significant p<0.01, significant p<0.05, no correlation p>0.05) of the different orofacial items in relation to orthopedic findings (top) and to orofacial myofunctional findings (bottom).

a: Positive habit history
Significant (p=0.001)	Significant (p=0.005)	No Correlation
Weak body posture (p=0.000)		Upper cervical spine (p=0.872)
		Iliac spine (p=0.496)
Open mouth rest posture(p=0.001)	Incompetent lips (p=0.013)	Reclined head position (p=0.174)
Articulation disorders (p=0.000)
Habits (p=0.000)
Tongue dysfunction (p=0.000)
b: Persistent habits
Significant (p=0.001)	Significant (p=0.005)	No Correlation
Weak body posture (p=0.000)	Iliac spine (p=0.019)	Upper cervical spine (p=0.356)
Articulation disorders (p=0.000)
Open mouth rest posture (p=0.000)
Tongue dysfunction (p=0.000)
Reclined head position (p=0.008)
Incompetent lips (p=0.007)
Habit history (p=0.000)
c: Incompetent lip closure
Significant (p=0.001)	Significant (p=0.005)	No Correlation
Weak body posture (p=0.000)	Upper cervical spine (p=0.021)	Iliac spine (p=0.628)
Open mouth rest posture (p=0.000)	Tongue dysfunction (p=0.023)
Articulation disorders (p=0.000)	Habit history (p=0.013)
Reclined head position (p=0.000)
Habits (p=0.007)
d: Mouth rest posture
Significant (p=0.001)	Significant (p=0.005)	No Correlation
Weak body posture (p=0.000)		Iliac spine (p=0.257)
		Upper cervical spine^p(p=0.772)
Incompetent lips (p=0.000)	Reclined head position (p=0.029)
Tongue (p=0.000)
Habit history (p=0.000)
Articulation disorders (p=0.000)
Habits (p=0.000)
e: Tongue dysfunction
Significant (p=0.001)	Significant (p=0.005)	No Correlation
Weak body posture (p=0.000)	Iliac spine (p=0.017)	Upper cervical spine (p=0.452)
Reclined head position (p=0.000)	Incompetent lips (p=0.023)
Habit history (p=0.000)
Articulation disorders (p=0.000)
Open mouth rest posture (p=0.000)
Habits (p=0.000)
f: Articulation disorders
Significant (p=0.001)	Significant (p=0.005)	No Correlation
Weak body posture (p=0.000)	Iliac spine (p=0.020)	Upper cervical spine^p(p=0.161)
Habits (p=0.000)	Reclined head position (p=0.011)
Habit history (p=0.000)
Tongue dysfunction (p=0.000)
Mode of breathing (p=0.000)
Incompetent lips (p=0.000)
g: Reclined head position
Significant (p=0.001)	Significant (p=0.005)	No Correlation
Weak body posture (p=0.000)
Upper cervical spine (p=0.000)
Iliac spine (p=0.000)
Habits (p=0.008)	Articulation disorders (p=0.011)	Habit history (p=0.174)
Incompetent lips (p=0.000)	Open mouth rest posture (p=0.029)
Tongue dysfunction (p=0.000)

a-f.

Correlations within myofunctional disorders

All assessed orofacial dysfunctions correlated statistically significantly with at least five further dysfunctions. Open mouth rest posture (p=0.029) and articulation disorders (p=0.011) correlated significantly with a reclined head position. Incompetent lips correlated significantly with all other assessed myofunctional items. Table 1a-f give a precise representation of the single relations.

DISCUSSION

The prevalence of orofacial myofunctional disorders (OMD) in this study population is approximately 70%. “The generally accepted prevalence of orofacial disorders is 38% in the general population” (Kellum, Gross, Hale, Eiland and Williams, 1994). Therefore, OMD are present twice as often in children with a radiologically proven alteration of the occipito-cervical region than in healthy children.

The significant higher prevalence of tongue dysfunction and habit history in the younger age groups up to 10 years demonstrates the earlier proven maturation of the oral motor skills with age (Laine, Pahkala, Jaroma and Qvarnstrom, 1992; Pahkala, Laine and Nahrhi, 1995). On the other hand it becomes obvious, that certain orofacial dysfunctions appear to be associated with each other during growth (Laine, Pahkala, Jaroma and Qvarnstrom, 1992; Pahkala R, Laine T and Nahrhi M, 1995).

The even higher prevalence of OMD in this study group might be explained by alterations to the soft and hard tissue since in addition to a radiologically evident impairment of the upper cervical spine a functional orthopedic asymmetry was revealed in every child.

The statistically significant correlations between orthopedic findings and OMD imply the existence of an interaction between postural alterations and orofacial function. As soon as the balance of form and function is disturbed OMD, dental, skeletal, orthopedic, and postural alterations occur.

Weak body posture seems to be the most dominant orthopedic variable affecting or being affected by OMD. Our observation concurs with the findings of Wachsman (1960) who reported a high incidence of proganthia in children with a hypotonic body posture and hypotonicity of the muscles of the masticatory system, tongue and face. According to Wachsman, the origin of the “circulous vitiosus” of alterations in the orofacial development is the genetically determined insuffiency of the mesoderm. However, scientifically based evidence is still missing. Other authors suggest holistic therapy concepts for the treatment of the multiple findings (Rocabado, 1987; Bahnemann, 1981). Therefore, neuromuscular exercise programs have been developed to strengthen the orofacial muscles and to achieve long-term stability after orthodontic treatment.

Based on the significant correlations with weak body posture, mouth breathing, habits, sigmatism and tongue dysfunctions, the early detection of negative habits seems to be very important in the prevention of further rehabilitation difficulties. Negative habits in the oral region disturb the balance and evoke further OMD. This aspect has been indicated in published literature (Kellum, Gross, Hale, Eiland and Williams, 1994; Wadsworth, Maul and Stevens, 1998).

The generated data also underline the importance of a physiological head position, since all analyzed orthopedic alterations correlated significantly with a reclined head position. Solow and coworkers (Solow and Kreiborg, 1977; Solow and Siersbæk-Nielsen, 1992, Solow and Sandham, 2001) studied the relation between natural head position and facial development for over 30 years and demonstrated that head posture influences facial development. One explanation suggested for their results was the ”soft-tissue stretching“ hypothesis. This model is based on a chain of events which are linked by neuromuscular feedback. Morphological alterations, narrowness of the airway, and alteration in posture lead to a changed force of the soft tissue on the facial skeleton and modulate the facial growth. Hellsing and L’Estrange (1987) confirm the validity of this model with the observed changes in lip pressure in anteflexion of the head.

With reference to the literature on this issue, the present authors have developed a theoretical model of the “interactive functional box system“ [Figure 5] in order to provide an explanation for the observed high prevalence of orofacial dysfunctions and to provide a better understanding of the correlations between alterations of orthopedic and myofunctional impairments as well as different relationships within myofunctional disorders. The orofacial and craniofacial region in particular as well as the whole body posture defined by muscle tonus is divided anatomically into different boxes that are combined by function.

The functional boxes are defined as follows:

• NASAL CAVITY AND NASAL SINUSES (plus EPIPHARYNX):
• with the important role of habitual nose breathing (respiration)
• LIPS: entrance of the mouth. Play an important role in nasal respiration, tongue position, and incisor inclination.
• ORAL CAVITY with TONGUE and TEETH (plus MESO- and HYPOPHARYNX) : swallowing, mastication and speech are the three major functions within this box.
• INFRA- AND SUPRAHYOID
• MUSCLES: contribute to the orthostatic equilibrium of the lower part of the skull
• OCCIPITO-CERVICAL REGION:
• stabilization and movement of the head
• GENERAL MUSCLE TONUS: body
• posture defined by muscle strength

Under normal physiological conditions, the different boxes interact in function and support each other, resulting in physiological development. If the balance of power between the different boxes is disturbed, normal functioning and development are impaired. Stable results can only be achieved by causal therapy. Any relapse might be due to an inadequate diagnosis.

Individual studies have already demonstrated that myofunctional therapy involves far more than correcting abnormal tongue position and function: Schievano, Rontani and Berzin (1999) recorded improvement in the morphology and function of the muscles in habitual mouth- breathing patients. Pierce (1983) reported a relation between mode of breathing and tongue function.

Dental changes have been observed after orofacial myofunctional therapy (Benkert, 1997; Garetto, 2001). Other authors reported a self-correction of articulation disorders during ongoing myofunctional therapy (Bigenzahn, Fischman and Mayrhofer-Krammel, 1992; Pierce 1996; Umberger and Johnston, 1997).

Taking the scientifically proven complex relation between orofacial function and dysfunction, posture and hard tissue changes into account, the data presented here provide the scientific background for the already mentioned demand for a collaborative approach (Paul-Brown and Clausen, 1999) at the time of diagnosis and treatment in children with OMD to ensure physiological development of the orofacial region as well as of the vertebral column. Successful treatment of OMD has a high impact on orofacial and postural development. Due to this correlation the quality of training in orofacial myofunctional phenomena must address all involved medical disciplines and be of high quality.

The presented results are first trends of a pilot study. Further clinical studies will follow in order to gain further knowledge of the causalities and to provide a greater understanding of the complexity of the orofacial balance.

CONCLUSION AND RECOMMENDATIONS

• The high prevalence of orofacial dysfunctions in children with orthopedic disorders implies an interaction between form and function.
• As a multifactorial pathology seems to be the most likely explanation for postural alterations, an interdisciplinary treatment approach is essential for success.
• Early multidisciplinary screening in children with respect to posture, orofacial function and orthopedic alterations may help prevent a disturbed orofacial development and dispense with further cost- intensive treatment approaches. The balance of form and function within the orofacial region must be guaranteed as early as possible in order to allow the growth and developmental processes in the orofacial region and the vertebral column to continue in a normal physiological manner.
• Further research is needed to explore causes and effects in orofacial development.