M. El-Dakkak, BChD, HDD, MS
Department of Prosthodontic Dental Sciences, King Sand University College of Dentistry, P.O. Box 60169, Riyadh 11545, Saudi Arabia

Ten patients who had undergone soft palate resection for the removal of palatal tumors were studied. In each patient, the surgical defect involved the posterior margin of the soft palate and lead to velopharyngeal insufficiency. None of the patients suffered any speech, hearing or nasal problems before surgery. For each patient, a speech aid obturator was constructed and was used at least one month before the evaluation. Prosthetic management of each subject was evaluated as reflected in adequacy of velopharyngeal closure and speech competency. Various aspects of speech including intelligibility, articulation, nasality, hoarseness and overall speech were correlated with the adequacy of velopharyngeal closure.

The structural integrity of the hard and soft palates is vital for normal speech. Patients with palatal clefts usually have speech defects resulting from velopharyngeal incompetency1"3 or interference with structural integrity of the soft and/or hard palates.4,5
Speech may be influenced by palatal defects via the inappropriate coupling of the nasal cavity and/ or changes in the capability to impound, direct and constrict airflow.5
Repair of such defects may be accomplished by surgery, prosthetic replacement, or a combination of both,6 but prosthetic restoration remains the desirable treatment in patients with large palatal defects.7
The prosthetic management of hard palatal defects is more successful than soft palatal defects due to inherent movements of the unresected por­ tion of the soft paiate, which often interferes with prosthetic restoration.4
This study attempted to evaluate the efficacy of prosthetic management in resected soft palate patients as reflected in the adequacy of the vel­ opharyngeal closure and speech competency. The velopharyngeal closure was measured by the assessment of pressure flow parameters and was correlated with the competency of the various aspects of speech including intelligibility, articula­ tion, nasality, hoarseness and overall speech.

The study included ten subjects, each of whom had received surgical resection of soft palate due to palatal tumor. Their paiatal defects involved the posterior margin of the soft palate leading to vel­ opharyngeal insufficiency [Fig. I],
All subjects had their surgical defect corrected with speech aid obturators. The obturators had been completed and placed for a minimum period of one month before the study so as to acquaint the patient with the prosthesis.
The speech aid obturators had been constructed to extend posteriorly into the pharyngeal region. In this manner, the action of both lateral and posterior pharyngeal walls could be utilized along with the action of the non-resected portion of soft palate. Such combined action achieves velopharyngeal closure during function. All of these resected soft palate patients still had an intact hard palate [Fig. 2].
The history of each subject revealed that none of them had had any speech, hearing or nasal prob­ lems before development of their tumors.
Methods of Evaluation of the Prosthetic Management
For each subject an evaluation of the prothesis, velopharyngeal closure, and speech competency were made.
Evaluation of the Prosthesis
Each prosthesis was examined for adequacy of retention and functional closure as follows:
-   the patient's ability to swallow without fluid escape through the nose
-   the patient's ability to speak
-   visual examination of the functional closure along the pharyngeal section of the prosthesis during pronunciation of a strong "Ah" sound.
Assessment of the Velopharyngeal Orifice Size
The equipment used consisted of a pneumotachograph for measuring the rate of air flow, two differential pressure transducers, and two- channel dynographs for recording the data in a graphic form. Such equipment has been described previously by Warren et al8 in an analysis of vel­ opharyngeal function [Fig. 3].
The technique used for evaluation of the nasal airflow and velopharyngeal orifice area was based on the assumption that velopharyngeal orifice size can be calculated from simultaneous measure­ ments of the pressure drop and airflow passing through the velopharyngeal orifice.8
The pressure drop across the orifice (oropharyngeal pressure minus naso-pharyngeal pressure) was measured by using a differential pres­ sure transducer. One of the two pressure catheters (PE 200 tubing) was placed in the left nostril and the other in the oropharynx. The nasal catheter was secured using a cork which blocked the nostril, creating a stagnant column of air. The oral catheter was held in the oral cavity during the speech seg­ ment. The tips of both catheters were blocked with
dental wax with small holes made around the walls of the distal end of the tube so that static air pressure could be measured.
Nasal airflow was measured by means of a heated pneumotachograph connected by plastic tubing to the subject's nostril. The parameters of pressure and airflow were converted to electrical voltages, amplified and recorded on heat sensitive paper. Velopharyngeal orifice area was calculated using the parameters of pressure and airflow using the hydrokinetic equation utilized by Warren et al8 for this purpose.
K = Correction coefficient = 0.65
Density of air = 0.001 gram/cm3
Each subject phonated a series of test syllables and sentences with the pressure flow apparatus in place. The speech sample was heavily loaded with the sound "P" which requires a high intra-oral pres­ sure for adequate production [Fig. 4].
Speech Evaluation
The equipment used consisted of ampex tape recorder (AG - 600 B), speaker amplifier (AA - 620), shure microphone (Unidyne III Model 545, dynamic), and scotch recording tapes (low noise Dynamag magnetic tape 211) [Fig. 5].
The technique used for recordings was similar to that reported by Oral.9 Each subject was seated in a sound proof room facing the microphone at a fixed distance and was asked to pronounce each word as carefully as possible (Fig. 6]. For each sub­ ject's recording, a certain speech recording schedule described by Oral was used.9
Three speech pathologists rated the recordings independently by listening to the master speech tapes of each of the ten patients. The sequence of the experimental conditions had been changed for each patient. Thus, the speech pathologists had no prior knowledge about which experimental condi­ tion was being evaluated at any point in time. Each recording was evaluated using a seven point scale (1-normal; 7-inadequate). The scores were applied to intelligibility, articulation, nasality, hoarseness, and overall speech.

 
The results demonstrated incomplete vel­ opharyngeal closure in 80% of the subjects, i.e., orifice size was greater than  zero,  while 20% showed complete closure, i.e., orifice size was zero. The linear correlation coefficient (r), was used to test the correlation between the adequacy of vel­ opharyngeal closure and intelligibility, articulation, nasality, hoarseness and overall speech. Student "t" test was used to determine whether the greater than zero orifice sizes differed significantly from zero.10 The results are shown in Table 1. The find­ ings showed a statistically significant correlation between velopharyngeal orifice size and intelligi­ bility (r=.749 and t=3.93). Increasing vel­opharyngeal orifice size adversely affected intelligi­ bility in prosthetically managed patients.
Articulation was significantly and inversely related to orifice size (r =.665 and t = 2.52). Increasing orifice size reduced the adequacy of speech articulation. Additionally, there was a statistically significant correlation between nasality and velopharyngeal orifice size in prosthetically managed patients (r =.785 andt =3.59). increas­
ing orifice size accompanied increasing nasality.
On the other hand, the results showed no statisti­ cally significant correlation between the vel­ opharyngeal orifice size and hoarseness (r - .471 and t = 1.50) as well as overall speech (r = .609 and t = 2.17) (Table 1).

The principal objective of this study was to evaluate the efficacy of prosthetic management in resected soft palate patients as reflected by the adequacy of velopharyngeal closure and speech competency.
Results demonstrated incomplete vel­opharyngeal closure in 80% of the prosthetically managed subjects during production of the sound elements that require high intra-oral pressure and maximum velopharyngeal closure, e.g. "P" sound. This is probably due to the lack of pharyngeal wall movements resulting from the surgical resection and scar tissue contraction. This observation is consistent with those in previous studies,9,11 and may provide a basis for the clinical observation of hypernasality in prosthetically managed cleft palate speakers. It may simply arise from the condition that, in such speakers, the velopharyngeal space is too large to permit closure during pressure conson­ ants.
The complete velopharyngeal closure which was achieved in the remaining 20% of the prosthetically managed subjects may be relevant to the increased ability of muscular adaptation against the speech prosthesis.12
The findings indicated an improvement in articu­ lation and intelligibility following prosthetic man­ agement as a result of reduction in velopharyngeal port size and better sphincteric closure. However, the habits of dysarticulation are not corrected by obturators even when complete velopharyngeal closure is achieved. This has also been supported by Rosin and Bzoch.13 The reason, probably, is that speech articulation is produced not only by the soft palate, but is also performed largely through the movements of the lower jaw, lips, tongue, and soft palate.14 Thus, the use of training procedures in addition to adequate prosthetic management still is required to correct articulatory disorders. Cor­ rection of such conditions usually can best be accomplished by working with a skilled speech therapist.
Nasality became accentuated with an increase in velopharyngeal orifice size. It seemed reasonable
to assume that the increased rate of airflow through the velopharyngeal port led to an excessive amount of overtone resonance occurring in the nasal chamber. This can be corrected by adequate prosthetic management which may also eliminate the distortion of certain pressure sound elements, such as "P" sound.13
Adaptation of the muscle action following prosthetic management could restore, within vari-able limits, the nasalized characteristics of speech to an acceptable level. However, the fact that con­ trol of hypernasality following prosthetic restora­ tion was possible did not mean that it would be accomplished automatically during speech, and direct assistance was needed.
Hoarseness was not significantly related to the adequacy of velopharyngeal closure. While this observation appears not to have been discussed in any of the literature reviewed, it is possible to post­ ulate that since hoarseness is originally produced in the larynx and does not depend mainly upon the movement of the soft palate, it should indeed be unrelated to velopharyngeal closure.
The results did not exhibit a direct correlation between overall speech and velopharyngeal orifice size following prosthetic management. The interpretation to this observation could not be defi­ nite, since speech competency is also related to the integrity of oral structures which affect speech (eg. upper and lower jaws, teeth, lips, and tongue).
Although more definitive conclusions must await substantiation of these data in the form of a larger sample, it is appropriate at this time to suggest that a greater cooperation in clinical management by the maxillofacial prosthodontist and speech pathologist would contribute to speech improve­ ment.

  The conclusions that can be made obtained from this study are :