Orofacial myofunctional disorders (OMDs) are patterns involving oral and orofacial musculature that interfere with normal growth, development, or function of orofacial structures, or call attention to themselves (Mason, n.d. A). OMDs can be found in children, adolescents, and adults. OMDs can co-occur with a variety of speech and swallowing disorders. OMD may reflect the interplay of learned behaviors, physical/structural variables, and genetic and environmental factors (Maspero, Prevedello, Giannini, Galbiati, & Farronato, 2014).
Incidence and Prevalence
The incidence of orofacial myofunctional disorders (OMD) refers to the number of new cases identified in a specified period. The prevalence of OMD refers to the number of individuals who exhibit OMD at any given time.
Estimates vary according to the definition and criteria used to identify OMDs, as well as the age and characteristics of the population (e.g., orthodontic problems, speech disorders, etc.).
- Tongue thrusting (protrusion of the tongue between the teeth) during swallowing is estimated to range between 33% and 50.5% of the general population of school-aged children (Fletcher, Casteel, & Bradley, 1961; Gross et al., 1990; Hale, Kellum, Nason, & Johnson, 1988; Hanson & Cohen, 1973; Wadsworth, Maul, & Stevens, 1998).
- The presence of tongue thrusting (the protrusion of the tongue between the teeth) during swallowing is significantly related to age. Prevalence estimates are highest in preschool- and young school-aged children and lowest in adolescents (Fletcher, et al., 1961; Wadsworth, et al., 1998).
- Children with articulation disorders are more likely to exhibit a tongue thrust swallow (55.3%; Wadsworth, et al., 1998).
- Approximately 31% of children diagnosed with chronic mouth breathing (a common symptom of OMD) exhibit an articulation disorder (Hitos, Arakaki, Sole, & Weckx, 2013).
- Higher estimates are reported for individuals receiving orthodontic treatment (62% to 73.3%) or with dental malocclusions (Hale, Kellum, & Bishop, 1988; Stahl, Grabowski, Gaebel, & Kundt, 2007).
- In individuals with a temporomandibular disorder (TMD), the percentage of those with orofacial myofunctional variables is estimated to be 97.92% (Ferreira, Da Silva, & de Felicio, 2009).
Symptoms
Signs and symptoms of orofacial myofunctional disorders may include:
- Open mouth, habitual lips-apart resting posture (in children, adolescents, and adults)
- Structural abnormalities
- Restricted lingual frenulum
- Dental abnormalities, such as excessive anterior overjet, anterior, bilateral, unilateral, or posterior open bite, and underbite
- Abnormal tongue rest posture, either forward, interdental, or lateral posterior (unilateral or bilateral), which does not allow for a normal resting relationship between tongue, teeth, and jaws, otherwise known as the interocclusal space at rest, or the freeway space (Mason, 2011)
- Distorted productions of /s, z/ often with an interdental lisp. Abnormal lingual dental articulatory placement for /t, d, l, n, ʧ, ʤ, ʃ, ʓ/
- Drooling and poor oral control, specifically past the age of 2 years
- Nonnutritive sucking habits, including pacifier use after the age of 12 months, as well as a finger, thumb, or tongue sucking (Warren & Bishara, 2002; Warren, et al., 2005; Zardetto, Rodrigues & Stefani, 2002)
- Lack of a consistent linguapalatal seal during liquid, solid, and saliva swallows.
- Interdental lingual contact or linguadental contact with the anterior or lateral dentition during swallows.
Causes
No single cause of orofacial myofunctional disorders has been identified, and its causes seem to be multifactorial. Anything that causes the tongue to be misplaced at rest limits lingual excursions within the oral cavity, makes it difficult to achieve acceptable lip closure and reduces or impedes the ability to obtain and maintain correct oral rest postures leading to an OMD. The following factors may coexist and play a role in OMDs:
- Airway incompetency, due to obstructed nasal passages, either due to nasal structural obstructions (e.g., enlarged tonsils, adenoids, hypertrophied turbinates, and/or allergies, that do not allow for effortless inspiration and expiration) (Bueno, Grechi, Trawitzki, Anselmo-Lima, Felicio & Valera, 2015). These may result in upper airway obstruction and open mouth posture (Abreu, Rocha, Lamounier, & Guerra, 2008; Vázquez-Nava, et al., 2006), as well as an incorrect swallow pattern and mouth breathing (Hanson & Mason, 2003).
- Chronic nonnutritive sucking & chewing habits past the age of 3 years of age (Sousa, et al., 2014; Polyak, 2006; Zardetto, et al., 2002)
- Orofacial muscular/structural differences that encourage tongue fronting could include delayed neuromotor development, premature exfoliation of maxillary incisors that encourage fronting of the tongue, orofacial anomalies, and ankyloglossia.
Roles and Responsibilities
Orofacial myofunctional interventions are conducted by appropriately trained speech-language pathologists (SLPs), as part of a collaborative team. SLPs provide these services as members of interprofessional teams that may include the individual, family/caregivers, and other relevant persons (e.g., medical, dental, and orthodontic personnel).
According to the Preferred Practice Patterns (ASHA, 2004), the SLP conducts an assessment to identify and describe:
- Underlying strengths and deficits related to orofacial myofunctional factors that affect growth and development of the dentofacial structures, communication, and swallowing performance;
- Effects of orofacial myofunctional impairments on the individual’s activities (capacity and performance in everyday communication and eating contexts) and participation;
- Contextual factors that serve as barriers to or facilitators of successful communication and participation for individuals with orofacial myofunctional impairments.
The SLP conducts intervention that is designed to (ASHA, 2004)
- capitalize on strengths and address weaknesses related to underlying structures and functions affecting the individual’s orofacial myofunctional and swallowing patterns, as well as related speech patterns;
- facilitate the individual’s activities and participation by assisting the person to acquire new orofacial myofunctional skills and strategies;
- modify contextual factors to reduce barriers and enhance facilitators of successful communication and participation, and to provide appropriate accommodations and other supports, as well as training in how to use them.
Diagnosis
Interdisciplinary Team
Assessment of orofacial myofunctional disorders has many possible aspects, which often require an integrated team approach. The SLP should refer and collaborate with other professionals who may include one or more of the following:
- Allergist
- Certified Orofacial Myologist
- Dentist
- Oral Surgeon
- Orthodontist
- Otolaryngologist
- Physician
- Plastic surgeon
- Physical therapist
- Sleep Apnea Specialist
Case History
Diagnostic written history and interview with the client or the parents/caregivers if applicable conducted to help gather information regarding:
- Birth and developmental history
- Oral habits (e.g., thumb, digit, pacifier, object sucking, etc.)
- Prior Intervention (e.g., surgery, lactation, physical therapy, occupational therapy, speech-language pathology services, etc.)
- Respiratory habits (e.g., nasal breathing vs. mouth breathing)
- Medical history of conditions that might affect oral function including:
- Upper respiratory infections/allergies
- Ear infections/myringotomy
- Allergies – environmental and food influences
- Injuries or trauma
- Snoring and sleep habits
- Use of sleep appliance such as CPAP (continuous positive airway pressure) device
- Previous surgery history, such as (frenectomy, tonsillectomy and/or adenoidectomy, or maxillofacial orthognathic (jaw) surgery
- Dental/Orthodontic history
- Palatal expansion
- Orthodontic appliances and treatment plan
- History of temporomandibular joint dysfunction (TMD)
- Feeding History
- Tendency to drink liquids to assist swallows.
- Chewing with mouth open; noisy eater; messy eater; excessively slow eater; unusually small bites;
- belching excessively after meals
- Dislike foods with textures that require increased oral manipulation and chewing, such as meats, and other chewy foods.
- Speech & Language History
- Hearing history
Assessment of the Orofacial Complex
The clinician will visually examine the client for structural differences/abnormalities (e.g., proportion and symmetry) of the orofacial complex (including face, nose, eyes, ears, mouth,-skull, and profile). Particular attention should be paid to:
- the symmetry of movement of oral structures (lips, jaw, tongue, velum)
- abnormalities of the tongue (e.g., macroglossia, macroglossia, ankyloglossia, fasciculations) (Merkel-Walsh & Overland, 2017), including asking the client to lift lateral lingual edges to visually assess the frenulum (Martinelli, Marchesan, Berretin-Felix, 2018)
- size of tonsillar tissue about the airway (obstruction of the airway will force the tongue to move forward, creating an obligatory forward placement of the tongue)
- the configuration of the hard and soft palates
- status of the dentition, including occlusion
- tactile sensitivity outside and inside the mouth
Ankyloglossia also referred to as tongue-tie or short frenulum, is a medical diagnosis. The decision to clip or not clip the frenulum to treat tongue tie is a medical decision made on a case-by-case basis by physicians and dentists. As members of an interdisciplinary team, SLPs may be asked to provide input. If concerns regarding the frenulum’s structure or function arise during an examination of the orofacial complex, a referral to a physician or other medical professional should be made. There is evidence that division procedures improve breastfeeding function (Buryk, Bloom, & Shope, 2011), but limited data indicating the link between tongue tie, division procedures (i.e. clipping), and speech sound production outcomes (Chinnadurai, et al., 2015; Meaux, Savage, & Gonsoulin, 2016; Messner & Lalakea, 2002; Queiroz Marchesan, 2004; Webb, Hao, & Hong, 2013).
While awareness of malocclusion may be useful to the clinician, please note that diagnosing malocclusion is not within the SLP’s scope of practice. Malocclusions include the following:
- Abnormal/Excessive anterior overjet is often associated with Class II Division 1 malocclusion.
- Excessive overbite, often associated with Class II division 2 malocclusion (upright maxillary central incisors and facially blocked upper lateral incisors).
- Excessive anterior position of the lower jaw and teeth creates a negative anterior overjet in some individuals with Class III malocclusions.
- An open bite (lack of normal vertical overlap of teeth) that may occur anteriorly or posteriorly, on one or both sides of the dental arches.
- Dental cross bites may involve a single upper tooth or a segment of upper teeth being positioned lingual to lower teeth. A crossbite in the posterior dental arch may occur unilaterally or bilaterally.
Diadochokinetic Tasks
Hale and colleagues (1992) found that slower rates in diadochokinetic tasks were associated with postural differences.
- On single-syllable /pʌ/ measure, slower rates were associated with open-mouth postures
- During trisyllabic /pʌtʌkʌ/ measure, slower rates were correlated with decentralized postures of the tongue
Many clients with OMD may have difficulty disassociating the tongue from the mandible, leading to imprecise speech. They may be able to easily pass the diadochokinetic assessment task by compensating with the mandible rather than the tongue.
Oral Rest Posture
The typical rest posture consists of the lips closed, nasal breathing, teeth slightly apart, and the tongue tip resting against the anterior hard palate, at the lower incisors, or overlying gingiva. A forward tongue resting position or tongue tip protruding between anterior teeth can impede normal teeth eruption and result in an anterior open bite (Mason and Proffit, 1984; Mason, 1988).
Difficulty achieving lip closure, or closure with accompanying muscle strain, could be related to the presence of lip incompetence — abnormal lips-apart rest posture in children, adolescents, and adults (Mason, n.d. B). This is often due to unresolved airway interferences (e.g., allergic rhinitis, enlarged tonsils, etc.) and is associated with mouth breathing, dental changes, and speech production errors.
Lips-apart mouth posture is normal and age-appropriate before the lips are fully grown (Mason, n.d. B). The child’s oral mechanism, including the lips, tongue, and jaw, continues to grow and change into the teenage years (Vig & Cohen, 1979), with most individuals able to achieve lips-together resting posture around approximately 12-13 years (Mason, n.d. B; Vig & Cohen, 1979). However, some clinicians may address lip closure before this age, to avoid possible structural changes to the orofacial complex (Harari, Redlich, Miri, Hamud, & Gross, 2010; Hitos, Arakaki, Sole, & Weckx, 2013; Ovsenik, 2009).
Swallowing
Observe the client’s tongue and lip movements in the handling and swallowing of saliva, liquids, and foods. During the initiation phase of a client’s swallow, watch for the presence of an abnormal forward or interdental protrusion of the tongue tip. Tongue tip pressures exerted against the anterior teeth during swallowing are insufficient in duration to move teeth (Mason & Proffit, 1984; Proffit, 2000). Impaired chewing and anterior bolus loss are additional swallowing problems commonly associated with OMDs (Ray, 2006). The clinician may also note if the mentalis muscle or lower lip is being used to retain liquid contents, lack of hyoid excursion during the swallow, and lack of movement of masseters on palpation during swallowing.
Speaking/Articulation
Differentiation between developmental speech sound disorders (i.e., phonological processing), disorders of motor planning (i.e., Childhood Apraxia of Speech), and muscle-based speech sound disorders often present in OMD are critical. Assessment should focus on the placement of the articulators and the rest postures of the tongue, lips, and mandible when evaluating the speech of OMD clients. Differential diagnosis of a speech sound disorder should drive treatment methodology (Ray, 2003).
Imprecise articulation may be related to the inability to separate/differentiate the mandibular and lingual excursions within the oral cavity and the incorrect resting posture of the tongue and mandible. This incorrect resting posture becomes the location from which speech production begins and ends. Unless addressed before initiating traditional speech therapy approaches, the habitual resting pattern will continue to interfere with the habituation of the desired sounds.
The SLP evaluates:
- the resting position of the tongue, mandible, and lips during pauses in conversation.
- the placement of tongue for /t/, /d/, /n/, and /l/. Imprecise articulation may be noted for these phonemes, and are sometimes erroneously referred to as mumbling or lazy speech.
- any deviations of the jaw during connected speech.
- specific errors of articulation: /s/, /z/, / ʃ /, / t ʃ /, / ʒ /, /dʒ/. Note if they are produced interdentally, produced with lateralization, or noticeably against the upper or lower anterior dentition.
- /r/ distortion.
- distortion of velar sounds /k/ /g/, and /ŋ/.
- lack of posterior retraction of tongue on production of /r/, /k/, /g/, and /ŋ/.
- weak bilabial productions, including vowels and diphthongs.
- nasal quality of vowels (i.e., hypernasal or hyponasal). A chronic hyponasal voice quality suggests the presence of upper airway interference and the need for ENT and allergy workup.
Treatment
The primary purpose of orofacial myofunctional therapy is to create an oral environment in which normal processes of orofacial and dental growth and development can take place, and be maintained (Hanson & Mason, 2003).
Establish Patent Nasal Airway
When structural or physiological impediments to nasal breathing, including allergies, have been ruled out or corrected via evaluations by an allergist and otolaryngologist (ENT), achieving lip closure at rest can serve to stabilize a nasal pattern of breathing. Closed mouth posture cannot be consistently established until any airway interferences have been successfully resolved (Hanson & Mason, 2003). In addition to adenotonsillectomy by an otolaryngologist and rapid maxillary expansion by an orthodontist, orofacial myofunctional services have been utilized to promote nasal breathing.
Improve Speech Sound Articulatory Placement
An incorrect oral rest posture of the tongue and lips can result in the tongue initiating speech productions from an abnormal rest position. In such situations, correcting the OMD can positively impact the correction of speech production errors.
When an OMD is related to an abnormal lingual or labial or mouth open behavior pattern that coexists with speech production errors, the articulation errors can be expected to be corrected more easily once the behavior pattern has been corrected in therapy.
Eliminate Nonnutritive Sucking
Prolonged nonnutritive sucking (e.g., pacifier, finger, and object sucking) is a risk factor for increased malocclusion (Farsi & Salama, 1997; Polyak, 2006; Sousa, et al., 2014; Zardetto, Rodrigues, & Stefani, 2002). The American Academy of Pediatric Dentistry (2014) suggested dentists offer parents and caregivers guidance to help their children stop sucking habits by the age of 3 years or younger. In contrast, orthodontists do not usually make referrals to eliminate a sucking habit until close to the time that the adult incisors begin to erupt (Proffit, 2000). According to orthodontists, sucking habits that persist during the primary dentition years have little, if any, long-term negative effects on the dentition, and generally result in malocclusion only if sucking habits persist beyond the time that the permanent teeth begin to erupt.
Parents and caregivers can be taught to ignore problematic behaviors and offer praise, positive attention, and rewards as their child engage in appropriate mouth behavior to help the child break the habit.
Dental professionals have observed a limited success rate with punitive dental habit elimination appliances (e.g., a rake, crib, or thumb guard). Moreover, these punitive appliances have been associated with excessive weight loss, pain, poor sensory perception, and the development of atypical lingual movement secondary to the placement of these devices (Mason & Franklin, 2009; Moore, 2008).
Modify Handling and Swallowing of Saliva, Liquids, and Solids
Individuals with known OMDs may also demonstrate oral phase dysphagia which may require intervention.
Therapeutic intervention can involve the selection of appropriate oral tools such as straws, lip or bite blocks, appropriate food items, etc. for jaw-lip-tongue dissociation needed for eating and drinking.
Oral Rest Posture
A primary goal of orofacial myofunctional therapy is to create, recapture or stabilize a normal resting relationship between the tongue, lips, teeth, and jaws. Individuals who demonstrate difficulties with the patency of their nasal airway often remain mouth breathers, and this further affects normal resting postures of the tongue, jaw, and lips (Harari, Redlich, Miri, Hamud, & Gross, 2010). When the resting dimension (freeway space) has been achieved and stabilized in therapy, dental stability should follow (Mason, 2011).
Achieving a lips-together rest posture is another goal of orofacial myofunctional therapy. Therapy to achieve lip competence helps to stabilize the vertical rest position of the teeth and jaws, and may also positively influence tongue rest posture (Mason, 2011). Exercises to improve lip closure may include holding a tongue depressor between the lips (Ray, 2003), use of a lip gauge (Paskay, 2006), smiling widely and then rounding lips alternately (Meyer, 2000), and lip resistance activities (Satomi, 2001).
Labial-Lingual-Pharyngeal Muscle Resistance Exercises
Exercises to improve tongue, lip, and jaw differentiation include oral tactile stimulation and tongue movements without assistance from the jaw, such as tongue tip to the alveolar ridge or tongue clicks against the palate (Meyer, 2000). Isotonic and isometric exercises target the lips and tongue, to teach closed-mouth resting posture and nasal breathing.
Service Delivery
Format refers to the structure of the treatment session (e.g., group vs. individual) provided.
Provider refers to the person offering the treatment (e.g., SLP, trained volunteer, caregiver).
Dosage refers to the frequency, intensity, and duration of service.
Setting refers to the location of treatment (e.g., home, community-based). OMDs are usually treated in private practice, clinics, or hospital settings. OMDs are not typically treated in public school settings.
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