Dental anomalies and effects on speech
Children with cleft palate commonly have missing, rotated or extra teeth at the alveolar cleft site. The maxilla (upper jaw) may be narrow. These features may result in lateral or interdental production of /, ,, /.
Class III malocclusion, or underbite (where the lower jaw and teeth sit forward in relation to the upper jaw) is common in children with a history of cleft palate. This may affect tongue tip placement of alveolar sounds /t, d, n/ and can result in interdental and tongue blade realizations. Labiodentals /f, v/ may be inverted, being produced by the lower teeth contacting the upper lip.
Consider the effect of any existing dental appliance on the child's oral placement for speech. Read on for more detail on Dental anomalies and their effects on speech.
Dental anomalies and effects on speech
Dental problems are common in the cleft palate population. Kummer (2008) chapter 9 provides a comprehensive review of normal dental occlusion and common patterns of malocclusion and their potential effects on articulation. Peterson-Falzone chapter 6 provides helpful prompt-questions to help focus diagnostic thinking about the effects of dental and occlusal anomalies on speech. Some of the more common dental anomalies are summarised here.
Alignment of jaws and teeth
The normal alignment of the upper jaw (maxilla) to the lower jaw (mandible) is such that the molar teeth will occlude, and the upper incisors (front teeth) slightly overlap the lower incisors. The cusps (like mountains) of the upper molars fit into the fossae (like valleys) of the lower molars, such that the mandibular molar is a half of a tooth in front of the maxillary molar. This is referred to as "Class I occlusion"
Dental malocclusions can refer to either the jaws being misaligned, or the teeth being malpositioned such that they do not line up together properly.
Angle's classification is used to describe dental occlusion. While it describes tooth relationships, it is often supplemented with a description of skeletal relationships.
Class I occlusion
Class II malocclusion
Normal alignment of maxilla and mandible, normal dental occlusion. The term orthagnathic is also used.
The maxilla is protruded relative to the mandible, ie the top jaw sticks out further than usual. This could be due to a small mandible, a large maxilla, or a combination of both. This is also referred to as retrognathic.
The mandible is protruded beyond the maxilla, ie the top jaw is recessed further back than the bottom jaw. This may be due to a large mandible, a small maxilla, or both. This is also termed prognathic.
A class III malocclusion is reasonably common within the cleft palate population.
Crossbite is also quite common within the cleft palate population. In normal occlusion, the maxillary teeth overlap the mandibular teeth. When the mandibular teeth overlap the maxillary teeth, this is referred to as crossbite. In the cleft population, the maxilla can be narrow for a number of reasons, including (i) there is less tissue to start with, due to the presence of a cleft; (ii) maxillary growth can be restricted; (iii) scarring at the surgical repair site may also act to impair growth. Crossbite may occur in one, some, or all of the teeth.
These photos display both anterior and posterior crossbites in a patient who had a partial cleft of the hard and complete cleft of the soft palate. No lip or alveolar involvement.
An anterior crossbite describes the top incisors being positioned behind the bottom incisors. Anterior crossbite is common in cases of Class III malocclusion.
An anterior crossbite may result in an interdental production of alveolar sounds if the tongue remains in a normal position (a passive error). Otherwise, the child may actively compensate by pulling the tongue back: then sounds normally articulated with tongue tip to alveolar contact /s, z, t, d, n, l/ will be produced with tongue dorsum to palate contact. An anterior crossbite may also result in the production of an inverted /f/ (lower teeth to top lip).
A posterior crossbite may occur because the maxilla is narrow, and the upper molars sit medially to the lower molars.
Open bite describes when the upper and lower teeth (usually just the front teeth) do not close at rest. An anterior open bite can have a dental (thumb or dummy sucking habit) or skeletal origin.
An anterior open bite may result in interdental production of alveolar sounds.
A less common form of open bite is the lateral open bite. The anterior teeth overlap as normal but there is space between the posterior teeth. It can be unilateral or bilateral.
Posterior crossbite and lateral open bite on left side and posterior crossbite on right side of same patient.
Overbite describes the vertical relationship of the upper and lower incisors. Normally, the upper incisors overlap the lower incisors such that about 25% of the lower incisor is covered. An overlap which is greater than this is referred to as deep overbite or deepbite. This may happen to the extent that the lower incisors are completely overlapped by the upper incisors. This can be associated with oral cavity crowding and can affect the production of sibilants and tongue-tip sounds.
Overjet describes the horizontal relationship of the upper and lower incisors. In normal dentition, there is a small space between the upper and lower incisors (about 2mm if measured in a horizontal plane from the front surface of the upper incisor to the front surface of the lower incisor when the teeth are closed). If this space is greater, it is described as overjet. "Buck teeth" is one example of overjet. Another is a class II malocclusion. A handy mnemonic for overjet is to think of a jet flying forward.
This displays an increased overjet with a Class II molar relationship.
In addition to occlusal anomalies, children with cleft palate commonly have missing, rotated or extra teeth at the alveolar cleft site.
Missing teeth may result in a lateral or interdental production of sibilants, as the missing tooth or teeth affect tongue position and airflow.
Additional teeth can cause oral cavity crowding, and may affect tongue placement, particularly for alveolar sounds and interdental sounds. Sibilants may be lateralised.
Kummer (2008) explains the effect of dental anomalies on speech as follows:
"With normal occlusion, the tongue rests in the mandible behind the mandibular incisors. The maxillary teeth overlap the mandibular teeth. This leaves plenty of room for the tongue tip to articulate freely in the oral cavity against and under the alveolar ridge. In addition, the upper and lower lips are approximated, making the bilabial and labiodental sounds easy to produce. When there are dental or occlusal anomalies, however, this can inhibit the function of the tongue and lips, causing speech problems" (p. 243).
Click here to view a film clip of an adolescent with a Class III malocclusion. This 14 year old boy has a history of a complete left sided cleft lip and palate, with palatal repair surgery at 9 months of age and alveolar bone graft at approximately 10 years of age. Note in particular his production of alveolar sounds.
These film clips show his ability to improve his tongue tip to alveolar placement when prompted.
See also Kummer (2008) DVD clips 9-01 – 9-03.
Children with cleft palate often have various orthodontic appliances in place, which can also have an impact on articulation. The picture below shows braces. Another common appliance in the late primary to early high school years is the quad helix appliance. This is an orthodontic appliance for maxillary expansion. It has a wire across the hard palate which tends to interfere with airflow and tongue placement for speech, in particular for sibilants and affricates. It may be helpful to delay treatment of affected, non-stimulable sounds until the appliance is removed. (Golding-Kushner, 2001, p18, p.22). Liaison with the orthodontist regarding timing of treatment may be helpful.
Golding-Kushner, K.J. (2001). Therapy Techniques for Cleft Palate Speech and Related Disorders. Delmar, Cengage Learning.
This webpage pertains to management of children by the John Hunter Children's Hospital Cleft Palate Team. The resource information is aimed at qualified speech pathologists working within the geographical area of the Northern Child Health Network. It assumes a working knowledge of articulation and phonological processes in paediatric populations.