An innovative technique to restore velopharyngeal incompetency for a patient with cleft lip and palate

Abstract

Treatment of cleft lip and palate patients often demand well-coordinated work of medical and dental specialists. In spite of surgical and orthodontic therapy, prosthetic rehabilitation is always necessary because of partial anadontia, maxillary hypoplasia and velopharyngeal dysfuction. The aim of the prosthetic treatment is to improve aesthetics, function and speech of the patients; however, factors like underdeveloped and collapsed maxillary arch, retrognathic maxilla and reduced alveolar ridge height make the treatment challenging. This clinical report describes an interdisciplinary approach for the management of cleft lip and palate patient associated with mutilated dentition. The prosthetic phase began along with orthodontic treatment to achieve sufficient space distribution, which was restored with fixed dental prosthesis to stabilise the achieved status of occlusion. Palatal lift prosthesis was fabricated to restore the velopharyngeal incompetency with an innovative technique using ‘standard orthodontic expansion screw’ to eliminate hypernasality, decrease intelligibility of speech and to aid in deglutition.

Background

Despite the remarkable advancement in surgical management of oral and facial defects, many such defects especially of cleft palate cannot be satisfactorily repaired by plastic surgery alone. Several factors such as underdeveloped maxilla, collapsed maxillary arch, retrognathic maxilla, reduced alveolar ridge height and width and scar tissues make the treatment more challenging.^{1 2} Almost 80% of the cleft palate patients suffer from the defect of the velopharyngeal mechanism.^3–5 Surgery is considered as the preferred treatment for speech correction in such patients; however, it is not practically possible in numerous clinical situations like advanced cardiovascular or neurological disease (cerebral palsy), biomechanical limitations of surgery in conditions like cervical spine deformity or microstomia, anomalous medial deviation of internal carotid artery which is revealed by pulsations appearing in pharyngeal walls and confirmed by MRI or CT scan and psychological reasons. Prosthetic treatment combined with speech therapy is the treatment of choice for such patients.^6–9

Case presentation

A young female patient reported to the department of prosthodontics with missing teeth in the maxillary anterior region associated with mutilated dentition and difficulty in speech and deglutition. On intraoral examination, it was noticed that teeth 11, 12, 22 and 23 were missing with mesial rotation of 21. There was reverse overjet of 5 mm. She had a medical history of surgical repair of the cleft lip and palate in her childhood. There was closure of the cleft lip; however, cleft palate relapsed after few months. The patient was not willing for another surgery because of financial constraints. Her soft palate was drooping downward with the absence of uvula (figure 1). There was no relevant family history.

Figure1.

Velopharyngeal incompetency.

Investigations

The patient was asked to count from 1 to 10, to name the days, and to pronounce pressure consonants p/b/d/t/s/z/sh/t and sequences of /i-a/ and /u-i/. The patient was diagnosed with velopharyngeal incompetency that was confirmed by speech examination.

Treatment

Considering the clinical condition and age of the patient, mutilated dentition was corrected with orthodontic therapy followed by the replacement of the missing teeth with conventional fixed dental prosthesis. After 1 month, the patient was recalled for fabrication of the palatal lift prosthesis and speech therapy.

Fabrication of palatal lift prosthesis

The objective of fabricating the palatal lift prosthesis was to improve the resonance by displacing the drooping soft palate to the level of normal palatal elevation and decreasing the hypernasality by reducing the nasal emission of air during the production of oral consonants.¹⁰

Preliminary impression was made using irreversible hydrocolloid impression material. Referring to the cephalogram, soft palate section of diagnostic cast was altered to simulate the contour of raised soft palate. Remaining seats were prepared and secondary impression was made using light body elastomeric impression material with double mix single impression technique. Master cast was duplicated and wax pattern was fabricated according to the design principles of framework of palatal lift prosthesis. Wax pattern was sprued, invested and casted. Finishing and polishing of the metal framework was done and verified intraorally to check the fit of the prosthesis (figure 2). Heat-softened type I modelling plastic impression compound was adapted over the palatal extension of the metal framework. It was inserted into the patient's mouth to record the palatopharyngeal part of the prosthesis. The patient was instructed to bend the head forward slowly, touch the chest and then move it backward again as in nodding (figure 3). After that, side to side rotation was carried out. It helped to delineate the posterior extension of the prosthesis. More softened modelling plastic impression compound was added in the lateral side. The patient was asked to say ‘ah’ phonate repeatedly and forcefully.^11–13 The impression surface was examined and corrections were made until it was acceptable for speech and the comfort of the patient.

Figure 2.

Polished framework of palatal lift prosthesis.

Figure 3.

Recording of palatopharyngeal part.

Introduction of the new technique

Metal framework was cut at the junction of palatal portion and velar extension. The two halves of the ‘standard orthodontic expansion screw (Dentaurum, Germany)’ were separated by rotating the screw in the anticlockwise direction using the ‘key’. Atypical standard orthodontic expansion screw (Dentaurum, Germany) consists of an oblong body divided into two halves (figure 4). Each half has a threaded inner side that receives one end of a double-ended screw. The screw has a central bossing with four holes. These holes receive a key which is used to turn the screw. The turning of the screw by 90° brings about a linear movement of 0.18 mm. The pattern of threading on either side is of opposite direction. Thus, turning the screw withdraws it from both sides simultaneously. The first half of the expansion screw was soldered to the palatal end of metal framework and the other half to the velar part. After that, both palatal and velar parts were assembled together using the same ‘key’. Metal framework along with soldered expansion screw was positioned upon the master cast. Opening of the expansion screw was blocked out with modelling wax to prevent the flow of acrylic. The whole assembly was invested and acrylised using heat-polymerising resin. After complete polymerisation, the junction of palatal and velar extension part was cut so that it can be separated from each other with the help of the ‘key’ (figure 5). It can be adjusted upto 12–15 mm in anteroposterior according to the patient's comfort, speech and resonance modification. For vertical adjustment, the screw can be completely opened and two plates can be adjusted as per the requirement (figures 6 and 7).

Figure 4.

Standard orthodontic expension screw.

Figure 5.

Palatal lift prosthesis with key.

Figure 6.

Vertical adjustment of prosthesis.

Figure 7.

Intraoral view of palatal lift prosthesis.

The patient was referred to the department of speech therapy to assess the speech outcome before and after wearing the prosthesis. Three speech analyses tests were carried out.

1. Perceptual analysis—This test evaluated the intelligibility and resonance rating before and after the insertion of the prosthesis. While measuring the intraoral pressure with restricted soft palate movement in pronouncing pressure consonants like /pa/, the air predominantly passes through the nose. On the insertion of the prosthesis, expired air passes through both the nose and the mouth. Without prosthesis, the perceptual analyses was 0—poor; and with prosthesis it was1—fair (tables 1 and 2).

2. Acoustic analysis—It evaluated the formant frequency estimation for vowels /a/, /i/, /u/, before and after the insertion of prosthesis. Although most explosives were not clear before placement, insertion of palatal lift prosthesis permitted clear pronunciation of /p/ and /t/. There was also some improvement in the pronunciation of /k/, /b/ and /d/ (table 3).

3. Spectrogram/wideband—It was built from a sequence of spectra by stacking them together in time and by compressing the amplitude axis into a ‘contour map’ drawn in a grey scale. Words from the Hindi articulation test were used. The graph shows time along the horizontal axis, frequency along the vertical axis and the amplitude of the signal at any given time and frequency is shown as a grey level. Conventionally, black is used to signal the most energy, while white is used to signal the least (figures 8 and 9).^14–16

Table 1.

Perceptual analysis

Without palatal lift prosthesis	With palatal lift prosthesis (new technique)
0 (Poor)	1 (Fair)

Table 2.

Resonance rating

Without palatal lift prosthesis	With palatal lift prosthesis (new technique)
Severe	Moderate

Table 3.

Acoustic analysis (Formant frequency values in Hz)

Vowels	Without palatal lift prosthesis		With palatal lift prosthesis (new technique)
	F1	F2	F1	F2
/a/	527	1293	504	1020
/i/	254	1965	351	2391
/u/	278	547	329	724

Figure 8.

Spectrogram without palatal lift prosthesis.

Figure 9.

Spectrogram with palatal lift prosthesis.

Outcome and follow-up

The patient was recalled every 6 months and sent for speech analysis. Speech tests showed satisfactory results.

Discussion

Palatal lift prosthesis is used for patients with adequate palatal tissue, but poor control of velopharyngeal movements. It is currently considered as the only effective prosthesis for the management of velopharyngeal incompetence. It has two components—palatal section and palatopharyngeal section. The palatal section is securely retained by the teeth while palatopharyngeal part physically raises the soft palate.

An innovative technique of fabricating the palatal lift prosthesis using ‘standard orthodontic expansion screw’ is highlighted in this case report. The main advantage of this technique as compared to the other conventional techniques is the easy adjustability of the palatophryngeal section, patient's comfort and adaptability. From the physiological standpoint, it may be desirable that the palatopharyngeal section is movable and adjustable to better simulate soft palate movement during speech and swallowing. The palatal lift prosthesis fabricated using expansion screw can be adjusted in both vertical and horizontal direction upto 12–15 mm. with the help of the key. At the same time, it also subjectively prevents the regurgitation of food and liquid during swallowing. There was a significant improvement in the patient's speech as evaluated by speech tests like perceptual analyses, resonance frequency analyses, acoustic analyses and spectrogram (tables 1–3 and figures 8 and 9).

Palatal lift prosthesis fabricated by other conventional techniques is less retentive because of its greater bulk in the palatopharyngeal section. However, the prosthesis made with expansion screw is lighter in weight with minimal bulk. It satisfies the need for both the retention of palatal lift prosthesis and at the same time prevents the distortion of the expansion screw; otherwise, it can be distorted because of the force needed to elevate the soft palate. The conventional technique requires the addition of material in posterior extension in the palatopharyngeal section every 3 weeks to achieve optimal speech outcome and patient comfort; however, the present technique needs significantly lesser time to fabricate the prosthesis, approximately 1 week. The other advantage is that the appliance can easily be repaired if palatal extension is broken or the palatopharyngeal section can be remade instead of fabricating the complete prosthesis.

Learning points.

• The main advantage of this technique as compared to the other conventional techniques is the easy adjustability of palatophryngeal section, patient's comfort and adaptability.

• The palatal lift prosthesis fabricated using expansion screw, can be adjusted in both vertical and horizontal direction upto 12–15 mm. with the help of key.

• At the same time, it also subjectively prevents the regurgitation of food and liquid during swallowing.

• The appliance can easily be repaired if palatal extension is broken or the palatopharyngeal section can be remade instead of fabricating the complete prosthesis.