Speech rehabilitation of maxillectomy patients with hollow bulb obturator
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0973-1075.105692
Source of Support: None, Conflict of Interest: None
Aim: To evaluate the effect of hollow bulb obturator prosthesis on articulation and nasalance in maxillectomy patients.
Keywords: Maxillectomy, Nasalance, Obturator, Speech analysis, Speech intelligibility
Carcinomas of head and neck are the most frequent causes for surgical resection of the palate. It leads not only to surgical trauma but also psychological trauma due to residual facial defects or improper speech production, mastication, and articulation, which ultimately affects the quality of life of the patient. ,,
These patients require prosthetic  or surgical obturation  of the defect, to improve speech, deglutition, esthetics, and mastication. Prosthetic obturation is preferred because of shorter operative time, shorter postoperative hospital stay, and complete visualization of maxillectomy cavity which provides ease in oncologic surveillance.  The objectives of maxillofacial prosthodontic rehabilitation are restoration of missing teeth and, surrounding tissuerestoration of functions, esthetic appearance, preservation of remaining teeth, and physiological support to provide the potential for acceptable speech and swallowing. ,, Speech disorder in maxillectomy patients is an important clinical problem, as maxillectomy causes hypernasality  which affects articulation and speech intelligibility of an individual. Initially, a surgical obturator is given at the time of surgery to hold the surgical dressing and help the patient to swallow, aiding in the removal of the nasogastric tube. After surgical obturator, an intermediate obturator is given to restore speech and swallowing to some extent after complete healing, The definitive hollow bulb obturator is fabricated after complete healing of the defect, that is, around three months after surgery which restores speech, mastication, and swallowing. Different types of definitive obturators used to close the defect are solid bulb obturator, hollow bulb obturator, and sectional obturator for people with reduced mouth opening.Authorities have claimed that hollow bulb obturator is better and helps in rehabilitation with its reduced weight  and increased retention.  This study was designed to evaluate the effect of definitive hollow bulb obturator prosthesis on various speech parameters assessed before and after maxillectomy.
Ten cases that were to undergo maxillectomy in the age range of 15-75 years (mean age: 43 years) irrespective of gender were selected; 50% of the cases had squamous cell carcinoma. Patients who were to undergo chemotherapy and radiotherapy with normal hearing pattern were included in the study [Table 1]. Patients who were completely edentulous or had medical problems like neuromuscular disorders, damaged vocal cords, hearing defect, and so on were excluded from the study. All the subjects were Hindi-speaking and were deemed to be unaffected by any cognitive impairment. Ethical clearance from the institutional ethical committee was taken before commencing the procedure.
Fabrication of obturator
The presurgical obturator plate was made from self-cure acrylic (Trevlon, Dentsply India Pvt Ltd). The presurgical obturator plate was placed in the mouth of each patient at the time of surgery. After a healing period of about two weeks, the presurgical obturator was replaced by an intermediate obturator, fabricated in heat-cured poly (methylmethacrylate) (Trevlon, Dentsply India Pvt Ltd). The definitive hollow bulb obturator was made after complete healing of the defect (3-4 months).The obturator was fabricated using a conventional method, and intraoral adjustments were made. The definitive obturator was made for each patient with full bulb height for which an alginate impression was made and the cast was blocked for undesirable undercuts. Certain specifications were followed for fabrication of the obturator, for example, the medial side of the obturator was restricted by nasal turbinates; so, a relief was given. The superior extension should provide space for nasal breathing, and anterior aspect should be higher than posterior aspect as anterior combined with lateral aspect provides support for the facial muscles which helps in providing better esthetics and function. Inferior and lateral extension should not restrict the mandibular movement; lost salt technique' was used to make the obturator hollow. A hollow maxillary obturator may reduce the weight of the prosthesis by up to 33%, depending upon the size of the maxillary defect.  The patient was asked to wear the obturator after which the speech analysis was done after 24 hours and six weeks of placement.
Speech was analyzed for articulation and nasalance
Articulation was assessed by an Indian articulation test given by Pandit et al.  All the parameters were assessed by a speech pathologist which comprised number of error patterns (substitution, distortion, omission or addition), number of sounds misarticulated (sum of distortion, substitution, addition and omission), most frequent position of error, and consistency of error and speech intelligibility. These were calculated by a careful listening of the speech of the patient using the articulation test and calculating the number of errors. Speech intelligibility was measured on a seven-point scale  by the speech pathologist [Table 2].
Nasalance was assessed by the nasal view of Dr. Speech software (Tiger DRS Inc, Seattle, Washington, USA). The patient was asked to phonate a vowel keeping the receiver at the base of the nose to get the percentage of nasalance.
Both the parameters of articulation and nasalance were assessed at four different intervals, that is, preoperative recording, after complete healing before the placement of the definitive obturator, 24 hours after placement of the definitive hollow bulb obturator, and six weeks after the same.
The data was entered on a Microsoft Excel data spreadsheet and analyzed with the help of the SPSS software version 15.0. A descriptive analysis was done with repeated measures of analysis of variance (ANOVA) for all data except speech intelligibility. Friedman's analysis was done for speech intelligibility with Bonferroni correction.
On evaluating for error pattern, it was seen that distortion was maximum followed by substitution; omissions and additions were negligible.
The mean value of distortion [Table 3] changed from 0.6 ± 0.5 words before surgery (baseline value) to 40.0 ± 0.6 words post surgery after complete healing. After providing the definitive obturator, the mean value changed to 23.7 ± 5.9 words after 24 hours and 6.3 ± 3.3 words after six weeks [Table 3]. On comparison of data with baseline values, the difference in the mean values showed statistically significant results (P0 = 0.001). Distortion decreased with time on providing the obturator. The distortion was mainly associated with dental, dentoalveolar, alveolar, and labiodental sounds.
The mean substitution increased from 0.9 ± 2.0 words to 7.5 ± 6.0 words post surgery after complete healing. The mean decreased to 2.4 ± 3.4 words and 1.2 ± 2.0 words after 24 hours and six weeks of providing the obturator, respectively. When compared to the baseline value, the substitution at 24 hours and six weeks was insignificant ( P > 0.05). The data elucidated that the number of substituted words decreased on providing the hollow bulb obturator, but the value was statistically insignificant. Omission and additions were not seen in any of the patients.
Number of sounds misarticulated: It was found that the mean number increased from 0.3 ± 0.9 words to 15.9 ± 2.6 words postoperatively ( P = 0.001), which became 8.7 ± 2.5 words 24 hours after providing the obturator and it further decreased to 2.7 ± 0.9 words after six weeks. So, the mean misarticulation decreased after providing the obturator. The decrease in misarticulation was more with time ( P < 0.05).
Most frequent position and consistency of error
It revealed that patients showing preoperative errors in speech were showing errors in all positions post surgery also, irrespective of the presence of the obturator and all the subjects showed consistency in the errors.
Speech intelligibility decreased after surgery. As compared to baseline where 10% patients had a score of 1, it was seen that postoperatively, 30% of the subjects had a score of 6 and 70% had a score of 5. After placing the obturator, it was seen that intelligibility improved in 70% patients with a score of 3, 20% with a score of 4, and 10% with a score of 5. After six weeks, it was seen that the speech improved further in 30% patients with a score of 1 and 70% of the patients with a score of 2 [Figure 1].
Nasalance increased significantly from 20.16 ± 5.52 to 52.04 ± 19.25 after surgery ( P = 0.005); it decreased to 25.87 ± 8.37 ( P = 0.006) 24 hours after providing the obturator. The nasalance reached near-normal levels after six weeks of providing the obturator; the mean nasalance becomes 21.21 ± 5.71 with time.
When the baseline values were compared with final values after six weeks, the difference in the mean was insignificant, which shows that the value of nasalance reached near-normal levels [Table 4].
Overall nasality was found to be significant (P < 0.05).
Articulation is a configuration of the larynx, and the pharyngeal, oral, and nasal cavities resulting from the positioning of the mobile organs of the vocal tract (tongue) relative to other parts of the vocal tract that may be rigid (palate). Voice is produced by modification of the airstream by the tongue and hard palate. An inaccurately produced speech sound/s is called misarticulation which is characterized by the substitution, omission, distortion, and addition of phonemes.
Substitution is the replacement of one standard speech sound by another such as/Ө/for/s/or replacement of one standard speech sound by a non-standard speech sound;  distortion is the approximation of a phoneme in the same manner which renders it acoustically unacceptable.  In the present study, the substitutions and distortions were the most commonly occurring articulatory errors and it was mainly for dental, dentoalveolar, affricates, and fricatives, which is in accordance with the study by Johnson et al.,  who observed that the most frequent substitution sounds were/p/,/b/,/t/,/k/, and/g/in cleft palate patients, influenced by the position of the tongue, of the teeth, and the palatal area.
Distortions were also associated with the extensive resection of the palate when the patient was edentulous. This was due to the inability of the tongue to articulate with the palate. It causes distortion of sounds as the tongue has its customary position of producing sounds and because of the missing palate, the tongue is not able to articulate due to the resected palate causing an escapement of air through the nasal cavity which causes difficulty in pronunciation of Hindi phonemes like 'pa', 'fa','ba','bha', 'cha', 'ja', 'jha', 'sa', fricatives like/f/,/v/,/s/, and/z/, and affricates like/ch/and/j/.  After providing the obturator to the patient, it was possible for the tongue to articulate with the acrylic palate, which helped in decreasing both distortion and substitution but the tongue had still not adapted to the obturator palate. After a period of six weeks, there was betterment in speech, with less distortion and substitution. The obturator was still not able to eliminate the distortion and substitution completely but it reduced the number, which suggests that the articulation is completely a matter of the tongue and hard palate and their co-ordination. The obturator obturates the defect and restores the oral pressure to an extent so that the patient is able to phonate.
Addition is insertion of sounds, but not a part of the word itself, for example, animamal for animal; omission consists of omitting certain sounds in words, for example, a-le for apple. Both addition and omission were absent on analysis of speech in our study.
Misarticulation is the incorrect production of sounds due to faulty placement, timing, direction, pressure, speed, or integration of the movement of the lips, tongue, velum, or pharynx. More misarticulations occur in voiceless consonants than their voiced cognates.  Post surgery without the obturator, after complete healing, the number of sounds misarticulated increased abruptly because of resection of the palate.
Speech intelligibility of the patients decreased after surgery; this was due to surgical resection of the palate which leads to nasalance and misarticulations in the speech, making it unintelligible. Postmaxillectomy speech disorders result from the distortion of the oronasal resonance balance and tongue to palate contacts.  The reports by Yoshida in 1990 and Umino in 1998 on the relationship between speech intelligibility without prosthesis and the grade of oronasal communication following maxillectomy , explains the reason for initial decrease in intelligibility. But after providing obturators to the patients, the speech intelligibility improved which is attributed to the palate, which helps in articulation, but the tongue takes time to get adapted to a new palate, which happens even in the case of complete denture wearers. So, the speech becomes partially intelligible in most of the cases but certain cases found it hard to adjust to the obturator. After a period of six weeks, the tongue got adapted to the palate, decreasing the misarticulations and making the speech more intelligible; nasalance is another factor contributing to speech. Sites concerning articulation revealed that speech disorders resulted mainly from poor oronasal separation in the non-reconstructed group and from incorrect linguopalatal contact in the reconstructed group, especially for linguodentoalveolar and lingua-velar sounds. The dentoalveolar and palatal contours of the maxilla must be restored as closely as possible to normal shape, for higher speech function. 
Muller et al., in their study found that a high nasalance score is typically found in sounds with a high proportion of nasal sound pressure, as in nasal consonants, for example, /m/,/n/, and/ng/.  This is in accordance with our study as there was significant change in the values. This signifies that nasalance of voice depends on the integrity of various resonating cavities. Once the integrity is lost, resonance of the voice is adversely affected; ,, as the patient undergoes maxillectomy, it causes hypernasality of voice as the air escapes through the defect. Adequate oronasal separation is required for proper intelligible sounds; so, the obturator plate was given to close the defect and to provide adequate oronasal separation which improves resonance. Therefore, in maxillectomy cases after rehabilitation, nasalance is eliminated and can be as low as in normal individuals. ,,
Rieger et al. described the importance of the anatomical region for postoperative success in cases of speech rehabilitation.  Pauloski et al., in 1998 showed that in certain maxillectomy cases, when nasal speech persisted inspite of an obturator, it was found that the defect was extending to the posterior border of the soft palate.  After the result and discussion, we finally conclude that the hollow bulb obturator tends to improve the articulation and provides adequate nasalance to make the speech intelligible. After rehabilitating the patients, we can definitely assume that it has improved the quality of life of the patients though we do not have a documented proof of it.
[Table 1], [Table 2], [Table 3], [Table 4]