Children with cleft palate often present with hypernasal speech, most commonly due to a structural deficiency of the velum. Some reports indicate that 20% to 43% of these children will still have velopharyngeal insufficiency following surgical palatal repair, and as a result may continue to sound hypernasal  . Velopharyngeal dysfunction may be treated surgically, prosthetically, by speech therapy, or a combination approach. The speech prosthesis may be the best choice in several situations where surgery is not the treatment of choice due to systemic, anatomic, or functional limitations or if the patient is not willing to undergo any surgical procedure  . The relationship between speech intelligibility and a speech prosthesis in patients with cleft palate is still a matter of concern, and there lies a continuous pursue to understanding more clearly the relationship between speech prosthesis and speech intelligibility and also improvising on the various methods and techniques to analyze, assess and manage patients with cleft palate defects.
Primary objectives for prosthodontic therapy include restoration of mastication, deglutition, and speech that is clinically and functionally acceptable. The definitive prosthesis generally used for this purpose is an obturator. An obturator should be a single piece either closed or open type. Accumulations of nasal secretions causing unpleasant odour and difficulty in polishing the internal surfaces are some of the disadvantages of an open type obturator  . Hence, a closed light weight hollow bulb obturator is preferred as it is easier to maintain  . Although, obturators aid in better mastication and deglutition, speech defects still persist to a large extent. Hence, the routine practice has been to put the patient on an intensive speech therapy. Patients with cleft palate have abnormalities in nasal resonance due to a velopharyngeal dysfunction. Speech bulbs aid as a stimulus intended to increase movements of the pharyngeal walls and palate, and hence, help to improve velopharyngeal closure  . Apart from this, existing articulation errors also result in reduced speech intelligibility  . Correlation between speech intelligibility and speech prosthesis is crucial and understanding this dimension thoroughly will definitely aid in enhancing speech intelligibility through prosthesis. Articulatory records between the tongue and the palate during various speech sounds can be recorded with palatography techniques. Commonly, marker paint is used on the tongue or palate to evaluate the articulation and are called linguograms or palatograms, respectively. In this case report, palatography was done using the correctable wax technique and the existing prosthesis was altered accordingly. The objective of this case report was to evaluate the alterations in speech intelligibility after extending the existing prosthesis to cover the soft tissue defect and modifying the palatal contour using the aforementioned technique.
2. Case Report
An 8-year old female patient reported to the department of Prosthodontics at Sree Mookambika Institute Of Dental Science, Kulasekaram, Tamilnadu. She had an existing prosthesis for correction of the defect, but complained that she was unable to speak clearly with the existing prosthesis (Table 1).
On intra oral examination a group II cleft palatal defect according to Veau’s Classification was present, which involved the hard palate and extended to the soft palate (velum) revealing a velopharyngeal defect as well. (Figure 1(a)) The
Table 1. Socio-demographic and clinical characteristics of child.
Figure 1. (a) Hard palate and Velopharyngeal defect; (b) patient’s existing prosthesis.
existing prosthesis did not cover the defect that involved the soft tissue part (velum). (Figure 1(b))
It was observed that, during speech the patient had high nasality and unintelligible speech. The initial treatment plan was to add a hollow speech bulb to the existing prosthesis.
The patient’s speech was evaluated in three clinical intervals. In the first visit, speech evaluation was done with the existing prosthesis. In the second visit, the analysis was done after adding a speech bulb to the existing prosthesis and in the third visit analysis was done after modifying the corrected prosthesis using the Korrecta wax palatography technique.
The speech was evaluated for nasality with a Nasometer. Praat software was used to evaluate the formants. Speech intelligibility was done using three vowels |a|, |e|, |u|, and was assessed using the listener scale. The patient’s parent’s consent was taken for the publication of this case report.
3. Clinical Procedure
A primary impression was recorded using Putty Impression material (Elite Zhermeck) after blocking the undercut intra orally by placing gauze. The cast was poured using Dental stone (Kalabhai). The existing prosthesis was tried on to the cast and the extension to the velopharyngeal defect was assessed. A 21-gauge stainless steel wire was incorporated onto the posterior extent of the prosthesis, which would aid in support of the impression material during recording the defect extending into the velum (Figure 2).
A pick up impression was done in putty. Impression Compound and green stick compound in the ratio of 7:1 was placed in a hot water bath and placed over the wired extension of the existing prosthesis. The velopharyngeal defect was recorded with the existing prosthesis along with the extension, which worked as the secondary tray (Figure 3).
During the molding of the velopharyngeal area the patient was asked to move her head forward by touching her chin on her chest and backward, and sideways touching her chin on her shoulders. This procedure was repeated until her nasality was considerably decreased. The patient was also asked to speak during the impression procedure.
The cast was poured with die stone, wax up was done and a hollow bulb obturator was constructed using salt method. Base of the obturator bulb was constructed using heat cure acrylic (Acrlyn-H, India) and the roof of the obturator was constructed using salt method using self-cure acrylic (Acralyn-H, India) (Figure 4).
Figure 2. A 21-gauge stainless steel wire incorporated onto the posterior extent of the prosthesis.
Figure 3. Velopharyngeal defect recorded.
Figure 4. Obturator bulb.
Figure 5. Intra oral correcta wax impression.
Figure 6. Final corrective impression.
The prosthesis was then tried in the patient. Speech was assessed using the intelligibility test by listener scale analysis. The patient showed decreased nasality and speech was more intelligible, but clarity of speech was still lacking. Hence, the palatal aspect of the prosthesis was coated with Korrecta wax and left to mould after asking the patient to repeat vowels and many words like shoe, cheer, fishing etc. The final corrective impression was made with Korrecta No 10 wax (factor II company). It was observed that the palatal contour took a different shape when she was able to speak more clearly (Figure 5, Figure 6).
This contour was copied and converted to acrylic resin and the prosthesis was polished and finished and speech evaluation with Nasometer and an intelligibility test using the listeners scale was assessed again. All the evaluation using nasometer and and Praat software analysis were done in a sound proof room of 20 db (Courtsey NISH Trivandrum). Speech intelligibility was tested using three vowels |a|, |e|, |u|, and was assessed using the listener scale.
A remarkable improvement in all the parameters was observed.
It was observed that the speech clarity for the vowels improved significantly after modification of the prosthesis. The values are depicted in Tables 2-4. There was an improvement of nasalance for the vowels after the modification of the prosthesis. The average (SD) percent scores for the 3 groups namely, existing prosthesis, prosthesis after extension and speech bulb, and after modification of the prosthesis with palatography technique for vowel |a| were 62.74% (1.55%), 56.64% (2.35%) and 25.32% (2.97%) respectively, for vowel |e| were 61.40% (1.03%), 54.80% (0.92%) and 17.34% (2.97%) respectively, and for vowel |u| were 52.93% (1.31%), 44.4% (2.78%) and 26.33% (2.60%) respectively (Table 5).
Table 2. Digital acoustic analysis using praat formants values for vowel |a|.
Table 3. Digital acoustic analysis using praat formants values for vowel |e|.
Table 4. Digital acoustic analysis using praat formants values for vowel |u|.
Table 5. Assessment of nasalance for vowels |a|, |e|, |u| using nasometer.
Failure of a primary palatoplasty to achieve a desirable functional velopharyngeal port can result in an array of speech problems, including hypernasality, inappropriate nasal air emission, often with development of compensatory articulation patterns in an attempt to produce oral pressure consonants. The extension of the defect beyond the velopharyngeal port results in hypernasality and reduction in speech intelligibility  . Yoshida, et al.  (2000), pointed out that hypernasality could be either mild or severe and it could generate discrete distortion or a drastic reduction in speech intelligibility respectively, thereby having a direct effect on an individual’s communication and social interactions. Data shows that perceptual ratings of resonance which are indicative of increased hypernasality were associated with poorer intelligibility  .
The literature reveals that as many as 25% to 50% of primary surgical closures of the hard and soft palate fail to adequately restore velopharyngeal function and consequently require one or more additional surgical procedures    or even require prosthetic treatment   to correct the problem. Many reports regarding prosthetic treatment of maxillectomized patients have shown a reduction in hypernasality and a significant increase in the percentage of correctly identified words    .
Fabricating a hollow obturator bulb is the most common treatment for velopharyngeal defects  . Of the different types of obturators, closed obturators have been commonly used  . There are several important patient background characteristics and factors, which have to be considered when looking at either clinical speech measurements or patient perceptions to obturator function. It is observed that patients who have undergone resection of maxilla and have dry mouths due to a history of radiotherapy or patients with reduced saliva and/or presence of thicker saliva experience impaired stability and retention of the prosthesis, with difficulties in sound articulation, associated with poorer intelligibility and impaired mastication and deglutition   . Obturators are known to function better during communication and swallowing in patients with smaller defects of the hard palate  . In individuals with complete unilateral hard and soft palatal defects, Sullivan et al.  found a mean intelligibility score of 46.5% in patients without prosthesis and 79.7% with prosthesis. In our study, we demonstrated improvements in speech intelligibility in the patient with the use of prosthesis, which is in agreement with results reported in the literature      . However, there was a further improvement in clarity after modification of the existing prosthesis using the correcta wax palatography technique.
Static palatography was the first concept to study consonants articulations during speech production  . The method consists of analyzing the contact area where the tongue touches the palate during the articulation. In order to visualize this contact area, before the consonant production, a paste made half of charcoal and half of olive oil is painted over the tongue. After the consonant production, the articulatory contact leaves a dark print onto the palate, which is analyzed to characterize the articulation. Palatography is said to be direct if the tongue touches the real palate. In this case, the tongue print is observed using a mirror. Palatography is said to be indirect, if an artificial palate is used.
Direct and indirect static palatography has been used in many studies for more than a century. But in the sixties, Electropalatography (EPG) came in and permitted the study of dynamic contacts of tongue to plate   . Electropalatography permits contact analysis over time, but it also has limitations. Only points on the palate where electrodes are located are considered and moreover, the artificial palate can disturb the speaker. The EPG plates that are available currently are expensive. Therefore, conducting studies with larger number of speakers becomes practically difficult.
Information about the shape of the palate is quite important in order to understand specificities of certain articulatory behavior patterns as previous studies have pointed out  . 2D image analysis have intrinsic limitations since the palate is not flat, and therefore simulating the shape of the palate as much as practically possible is a crucial step. In order to permit palate classification we propose extraction of the 3D shape to make palate comparison possible. Thus, in this case report we wanted to assess speech intelligibility in cleft palate patients using speech bulb and after altering the palatal contours of the existing prosthesis with palatography using Korrecta wax technique. It was observed that there was an improvement in speech clarity with the existing prosthesis, which was further enhanced with significant improvements by modifying the existing prosthesis using the corrective wax palatography technique. The alteration in the contour and the shape of the palate significantly enhanced the speech intelligibility. Mere placements of obturators in these patients definately help in improving functionality, but slight alterations in thickness and contour and extent of these prosthesis have a tremendous impact on the speech clarity and intelligibility. Understanding this dimension thoroughly will definitely aid in enhancing speech intelligibility through prosthesis.
The encouraging observations and results of this study provides us with a basis to carry out further research in this regard with the ultimate aim to provide near normal speech through prosthetic management.
To conclude, any defect of the maxilla can be corrected using surgical intervention or by prosthetic management but the ultimate aim to provide with a near normal speech lies in the hand of the maxillofacial prosthodontist, who should diagnose the defect and provide a better prosthetic rehabilitation. Modifying the prosthesis using palatography helps the patient to improve intelligibility in speech in very short span of time.