PRAXIS Oral Mech

The first molars serve as reference points for evaluating the occlusal relationship, which refers to the alignment of the upper and lower jaws. The upper and lower dental arches are compared with respect to these molar contacts. The occlusion, or the way the upper and lower teeth come together, is based on these molar contacts.

The upper dental arch is typically longer and wider than the lower dental arch. In occlusion, the upper teeth extend horizontally around the lower dental arch, and the upper incisors (maxillary incisors) protrude about one-quarter inch in front of the lower teeth, covering about one-third of the crown of the lower incisors. This relationship, known as dental overjet, is considered normal.

An open bite occurs when the upper teeth do not cover any part of the lower teeth along the dental arch. It means that there is a space or gap between the upper and lower teeth when they come together.

During occlusal evaluation, the client may be asked to bite on the back teeth and separate the lips. While in this occluded position, the client may be instructed to produce several speech sounds in isolation, such as /s/, /z/, /f/, and /v/. The standardization of airspace dimensions and changes in oral cavity pressure during speech can reveal functional relationships and uncover articulatory patterns related to occlusion. For example, a child with an interdental lisp may articulate /s/ more accurately with teeth together, which can provide insights into their speech production.

Mason and Wickwire suggested that individuals with excessive overjet and difficulty with /s/ should be instructed to rotate the mandible forward as a means of adaptation to the excessive overjet. This adjustment in jaw position may help in producing /s/ more effectively.

To view the hard palate (the bony portion of the roof of the oral cavity), the client is often asked to extend their head slightly backward. This position allows for better visualization of the hard palate.

A blue tint observed on the midline of the hard palate may indicate the need for further investigation into the integrity of the bony framework. This discoloration can be associated with a submucous cleft, which is an opening in the bony palatal shelf. However, if the blue tint is seen laterally (to the sides) of the midline, it usually suggests the presence of an extra bony growth, which is found in approximately 20 percent of the population.

During an examination, palpation (rubbing) of the mucous membrane at the midline of the most posterior portion of the hard palate (nasal spine) is recommended to detect a submucous cleft. A submucous cleft is indicated by the combination of (1) a missing posterior nasal spine, (2) a translucent area in the midline of the soft palate known as the zona pellucida, and (3) a bifid or divided uvula.

A submucous cleft of the hard palate is a structural abnormality that can impact speech and swallowing. It is important to identify a submucous cleft because it may require specific management or intervention to address speech and resonance difficulties associated with the cleft.

No, most individuals with high palatal vaults are able to compensate and use alternative movements that allow for adequate speech sound production. While the height of the hard palatal vault is often noted during an examination, it does not necessarily indicate speech difficulties on its own.

The soft palate or velum should be evaluated with the head in a natural upright position. This allows for accurate assessment of velar function as it occurs during speech, without any changes in the structural relationships in the oral cavity area.

According to Mason and Wickwire (1978), the assessment of velar function, especially velar elevation, should not be done with the tongue protruded or with the mandible positioned for maximum mouth opening. They recommend a mouth opening of about three quarters of the maximum opening, as velar elevation might be less than maximum when the mouth is open maximally.

The critical factor in velar function is the effective or functional length of the velum, which refers to the portion of tissue that fills the space between the posterior border of the hard palate and the posterior wall of the pharynx. The effective velar length is one factor in adequate velopharyngeal sphincter function but does not provide information about the function of the sphincter's pharyngeal component, which is another critical factor for adequate velopharyngeal valving.

Observing velar symmetry and elevation during sustained vowel production helps determine the functioning of the velopharyngeal sphincter. If the velum does not elevate or deviates to either side, it suggests an inadequately functioning velopharyngeal sphincter.

Confirming normal velopharyngeal closure is important because it involves not only the movement of the velum but also the movement of the posterior and lateral pharyngeal walls, which cannot be viewed from the mouth alone. Specialized procedures, such as nasendoscopy, lateral fluoroscopic X-ray, or speech aerodynamics, are required to assess velopharyngeal closure accurately.

A bifid uvula, which appears as two appendages instead of one, may indicate other anatomical deviations. It is occasionally associated with submucous clefts and other abnormal anatomical findings. However, if there is no excessive nasality in speech, a bifid uvula has limited diagnostic value on its own.

The presence or absence of tonsillar masses is noted, and their size and coloration are observed. Redness or inflammation could indicate tonsillitis, and large tonsillar masses may displace the faucial pillars and reduce the space between them (isthmus).

The pharyngeal contribution to velopharyngeal closure occurs at the level of the nasopharynx, which is superior to what can be observed through the oral cavity. Therefore, it cannot be assessed directly through intraoral viewing.

Passavant's pad is a prominence or ridge that can be seen on the posterior wall of the pharynx during sustained phonation in some individuals. It is not visible at rest. Its presence, particularly in individuals with cleft palates, may indicate a compensatory mechanism for velopharyngeal closure. The presence of Passavant's pad suggests the involvement of adenoidal tissue in velopharyngeal closure and may influence surgical decisions regarding adenoidectomies.

Instrumental measures, such as nasometer, videofluoroscopy, nasopharyngoscopy, and airflow (aerodynamic) measures, can supplement clinical perceptions and provide objective data on velopharyngeal adequacy and function. These measures can assess factors such as hypernasal resonance, production of pressured consonants, and nasal airflow, which are associated with inadequate velopharyngeal function.

Macroglossia refers to an abnormally large tongue. While historically it has been associated with Down syndrome, research data indicate that individuals with Down syndrome typically have normal tongue size. However, they may exhibit low muscle tone in the tongue and have a relatively small oral cavity, which can create the appearance of relative macroglossia.

Microglossia refers to an abnormally small tongue in relation to the oral cavity. However, this condition rarely, if ever, causes speech problems.

Observing tongue protrusion or lateral movement can provide information about possible motor limitations or problems with tongue control. It can help identify any restrictions or difficulties in tongue movements during speech.

Diadochokinetic tasks involve rapid syllabic repetitions (e.g., /pa pa pa, pa ta k^/), and they can provide information about speech function. The absolute number of syllables produced in a given unit of time is not directly related to articulatory proficiency unless there are gross motor problems. Instead, the focus should be on the pattern of tongue movement and the consistency of contacts during these tasks.

In most cases, individuals can acquire normal speech despite having a short lingual frenum. If the client can touch the alveolar ridge with the tongue tip, the length of the frenum is likely adequate for speech purposes. However, in rare instances where the tongue tip cannot reach the alveolar ridge due to severe restriction, surgical intervention may be necessary.