Speech intelligibility following prosthetic obturation of surgically acquired maxillary defects

Maxillofacial prosthetics

Speech

intelligibility

surgically Aziz

acquired

A.

Majid,

Varoujan

A.

Indiana

following maxillary

B;D.S., Chalian,

University

prosthetic

M.S.D.,*

obturation

of

defects Bernd

Weinberg,

Ph.D.,**

and

D.D.S.***

School

of

Dentistry

and Medical

Center,

Indianapolis,

Znd.

A

dvances in dentistry and medicine have been accompanied by new and more effective types of treatment for patients with head and neck neoplasms. The postsurgical rehabilitative techniques used by maxillofacial prosthodontists to replace surgically excised facial parts must be included among these advances. Maxillofacial prosthodontists are frequently called upon to restore craniofacial form and function in persons who have undergone partial resection of a maxilla. Although disturbances in speech represent one of the primary problems following ablative surgery of this type, little is known about the speech characteristics of persons who have undergone maxillectomy procedures. Studies of speech provide an opportunity to assess functional changes associated with surgery and subsequent prosthetic treatment. The broad objective of this study was to measure the speech intelligibility characteristics of persons who have undergone partial maxillary resection. The specific goal was to make postsurgical comparisons of the speech intelligibility characteristics of a group of patients speaking with and without a permanent maxillary prosthesis in the mouth. METHODS

AND

MATERIALS

Subjects

Six adults had undergone

(three women and three men) were selected for study. These patients partial surgical resection of the maxilla and had their surgical defects

This work was supported in part by research grants from the Marion County Cancer Society, Inc., and the United Health Foundation of Elkhart County, Ind. This research was conducted as part of an M.S.D. thesis submitted by Dr. Majid to Indiana University School of Dentistry. Read

before

the

*Associate

Instructor.

**Director,

Speech

***Chairman,

American Research

Department

Academy

of Maxillofacial

Prosthetics

in

San

Antonio,

Texas.

Laboratory. of Maxillofacial

Prosthetics.

a7

88

Majid,

Weinberg,

Fig.

1-6,

and

A. Site

Chalian

and

extent

of each

patient’s

surgical

defect.

restored with a maxillary prosthetic obturator at the Maxillofacial Prosthetic Clinic, Indiana University Medical Center. The patients ranged in age from 50 to 79 years? were edentulous in the maxillary arch, and by history, indicated that they had been “normal” speakers prior to surgery. A brief description of each patient and a summary of his treatment follow. Patient No. 1. A 79-year-old man had an epidermoid carcinoma of the right maxillary sinus. On Aug. 18, 1966, a right partial maxillectomy with excnteration of the right orbit was performed. The site and extent of this patient’s surgical defects are illustrated in Fig. 1, A. No radiation therapy was given before or after surgeq. His existing upper denture served as an immediate temporary obturator and was inserted at the time of surgery. A temporary obturator was constructed and placed on Sept. 20, 1966, and used until March, 1967, when the patient was given a permanent obturator (Fig. 1, B) Patient No. 2. This 61-year-old woman had an adenocystic basal-cell carcinoma (cylindroma) of the hard and soft palate. On May 3, 197 1, a left partial maxillrctomy was performed, creating a defect represented in Fig. 2, A. No radiation therapy was given before or after surgery. Her existing dentures were used as an immediate

Volume Number

32 1

Speech

Fig. l-6, B. Intraoral

after

prosthetic

view of each patient following

obturation

prosthetic

of

defects

89

treatment.

temporary obturator and were inserted during surgery. A temporary obturator was constructed on May 24, 1971, and used until she was provided with a permanent obturator on July 29, 197 1 (Fig. 2, B) . Patient No. 3. A 50-year-old man had a squamous-cell carcinoma of the left alveolar ridge. On May 11, 197 1, a left partial maxillectomy was performed, and his existing upper denture was used as an immediate temporary appliance. The site and extent of the surgical defect are illustrated in Fig. 3, A. No radiation was given before or after surgery. A temporary obturator was constructed on May 18, 1971, and used until Sept. 29, 1971, when he was provided with a permanent obturator (Fig. 3, B) . Patient No. 4. A 64-year-old woman had an epidermoid carcinoma of the right hard and soft palate. On Aug. 8, 1969, a right partial maxillectomy was performed with exenteration of the right orbit. The site and extent of the defect are illustrated in Fig. 4, A. Her existing upper denture was used as an immediate temporary obturator. No radiation was given before or after surgery. A temporary obturator was constructed on Aug. 12, 1969, and used until April 1, 1970, when she was provided with a permanent obturator (Fig. 4, B) .

90

Majid,

Weinberg,

and

Chalian

,I Prosthet. Dent. July. 1974

Patient No. 5. A 56-year-old man had a left maxillary sinus carcinoma. On Oct. 27, 1971, a partial left maxillectomy was done with exenteration of the left orbit. The site and extent of his surgical lesion are shown in Fig. 5, A. Cobalt therapy (6,500 rads) was given four weeks before surgery. An immediate temporary obturator was constructed and inserted at the time of surgery. A temporary obturator was constructed on Nov. 23, 1971, and used until Jan. 28, 1972, when he was given a permanent obturator (Fig. 5, B) . Patient No. 6. A 65-year-old woman had an adenocarcinoma on the right hard and soft palate. On Nov. 18, 1970, a right partial maxillectomy was performed. The site and extent of surgery are illustrated in Fig. 6, A. An immediate temporary ohturator was inserted at the time of surgery. Cobalt therapy (6,000 rads ) was given four weeks before surgery. A temporary obturator was constructed on Dec. 18, 1970, and used until April 8, 1971, when she was provided with a permanent obturator, (Fig. 6, B) . Audiometric tests were administered to each subject. The results of audiometrrc testing (pure-tone air and bone conduction and speech audiometry) indicated that each of these patients had adequate hearing for speech in at least one ear, Maxillofacial

prosthodontic

reconstruction

A standard series of procedures was used in the dental treatment of these patients.’ First, an immediate temporary or surgical obturator was constructed for each patient who had not used dentures before surgery. This baseplate prosthesis wa2; designed from preoperative impressions and was inserted into the patient’s mouth during surgery. The surgical obturator was used to close the resection, to hold SWgical dressings, and to provide limited physiologic assistance for speech and deglutition. The immediate temporary prostheses were removed within one month following surgery. An impression of the maxillary arch. including the resected area. was obtained for each subject at this time. This impression cast was used to construct a second prosthesis, called a temporary or intermediate obturator. This one-piece obturator consisted of a false palate, a false alveolar ridge, and a hollow bulb obturator which filled the resected area. No teeth were placed on this prosthesis. The false alveolar ridge of the intermediate prosthesis was made symmetric with the unoperated ipsilateral palate. In general, this obturator was designed to conform closelywith each subject’s presurgical oral morphology. Patients wore intermediate obturators for two to six months. These obturators served three purposes: ( 1) to give patients practice in retaining the prosthesis in the mouth, (2) to provide a period of observation for evaluating potential neoplastir recurrence, and (3) to allow time for healing and tissue shrinkage. The final stage of prosthetic rehabilitation was the construction of a permanent obturator. The intermediate obturator was removed, and a new impression of the maxillary arch and resected area was obtained. Following conventional complete denture procedures, the casts were used to construct a permanent obturator con sisting of a false palate, false alveolar ridge, hollow bulb obturator, and teeth. The permanent obturator was designed to achieve the best possible result for each patient in terms of oral-facial cosmetics and function. With respect to function,

Volume Number

Speech

32 1

after

prosthetic

obturation

of defects

91

the potential changes in speech after maxillary resection were carefully dealt with during construction of the permanent prosthesis. For example, the permanent obturator was designed to conform as closely as possible to each patient’s presurgical morphology in an attempt to minimize resonance changes in the vocal tract. Special efforts were also made to attain a close fit between the prosthesis and surrounding tissue to preclude leakage of air into the nasal cavity during speech. Speech

recordings

Each subject recorded six word lists, of 50 items each, from a Consonant Rhyme Test (CRT) described by House and associate? and six word lists, of 24 items each, from a Vowel Rhyme Test (VRT) recently described by Horii.” All recordings were made in April, 1972. Patients made these recordings under two experimental conditions: ( 1) with their surgical defects untreated-that is, in the absence of prosthetic obturation-and (2) with maxillary prosthetic obturation. Recordings were made in the Speech Research Laboratory, Indiana University Medical Center, with high-quality recording equipment. Subjects were seated in a soundproof room (IAC-Model No. 404A) facing a condenser microphone (Breul and Kjaer-Model No. 4131) placed approximately 12 inches from the speaker’s lips. The word lists were recorded without instrumental monitoring; however, each subject was instructed to maintain a constant level of vocal effort and to pronounce each word as carefully as possible. The recordings were edited by inserting a four-second silent interval after each word. In addition, an estimate of the signal level of each word was obtained by playing the rhyme-test word recordings at a fixed level into a high-quality tape recorder (Ampex-440). The peak 1evels of each word were visually read off the VU* meter of the tape recorder relative to the level of a prerecorded 1,000 Hz reference signal. These peak levels provided estimates of the signal level of each word and were used to calculate an average level for each CRT and VRT word list. The range in average word-list levels was less than 2.5 db. Consequently, the recordings were not adjusted for level variations during the listening experiment. listening

experiment

and

listeners

The listening experiment was conducted in a sound-treated laboratory built specially for group listening experiments. The rhyme-test recordings were monaurally presented to a group of listeners via earphones and high-quality listening equipment. The speech material was presented at an average level of 70 db SPLt measured under the headphones. The listeners were 15 college undergraduates with normal hearing and with no prior experience in judging speech and no familiarity with the type of speech being evaluated. Each listener was given a screening audiometric evaluation and was found to have an air-conduction threshold less than 15 db (ISO,$ 1964) for 500, 1,000, 2,000, 4,000, 6,000, and 8,000 Hz pure tones. Listeners evaluated 144 word lists-six speakers’ recordings of six CRT and *Volume units. tSound pressure level. ~International Standards

Or,~anization.

Table I. Differences in average intelligibility experimental condition (F values) *

tr’

T

O.lJi.

$P

-=

0.1J0l11.

SP

-=

0.005.

for each speaker

und(br ractl

six VKT lists spoken both with and without prosthetic obturation. ‘l‘he listening experiment \vas conducted in III daily one-hour sessions. The 144 lists wrre randomizcd across speakers. stimulus type 1CRT 1’s. VRT): and obturation conditions. For c~cll word presented! each listener identified his choice on a form with six alternati1.e choices. In short. a close-set rcsponsc strategy wxs employed. with listeners instructed to respond to each stimulus. RESULTS A com.entional measure of the avtarage intc*lligibilit)~ of speech is an articulation score.’ This sconb specifies the number or percentage of stimuli correctly identified by thr listeners. Accordingly. the listening data \v(Lrc initially summarized in the form of articulation scores for each 50 item CRT and each 24 item VRT word list recordrd by each patient (see Majid” for details). Analysis of variance techniques were applied to these scores to determint: lvhcthel thcbrc were diffrrcnces in average intelligibility as a function of a word list. These analyses arc sunlrnarized in Table I. ‘T‘wenty-four separate F tests were pc.rformed to assess the significance of thfz differences in average word-list intelligibility for each talker under eactl type of speaking condition. Nineteen of the 21 F \.alues were signific,ant. indicating that there were significant differences in the average intelligibility scores for sin,cle word lists. In \iew of these findings. we estimated the average intc~lligibilitv of each patient bv calculating L,irticulation scores basrd on the listeners‘ responses to all six CK’I’ and VKT word lists. rather than one. Each patient’s average intelligibility for CRT and VR’I’ materials is illustrated in Fig. 7. ‘l‘hrsc data highlight thr significant reduction in intelligibility associated with partial surgical resection of the maxilla. Among the six patients studied herca. average intelligibility for words spoken without prosthetic obturation was 62 per cent correct for CRT \vords and 58 per cent correct for VRT words. The data in Fig. 7 also point up the sizablr intersubject \,ariation in speech intelligibility following SW-

Speech

after

prosthetic

obturation

of defects

93

100 90 80 70 -

23 E 6050 s P 2

30-

E FG G::

20-

z

I

40-

loo-

2

*

80-i

20 10 01 Sl

Fig. 7. Intelligibility bars) and without

1

scores (per cent correct) for (empty bars) prosthetic obturation.

1tI II1

1 S6

CRT

and

VRT

Group

words

Average

spoken

with

(solid

gery. The range in articulation scores was about 40 per cent. Specifically, CKT scores for patients speaking without prosthetic obturation ranged from 41 to 80 per cent correct; for VRT words, scores ranged from 40 to 78 per cent correct. By comparison, prosthetic treatment produced a dramatic improvement in speech intelligibility for both CRT and VRT words in all subjects (see Fig. 7). There was a 34 per cent average increase in intelligibility for CRT material, and a 36 per cent average increase for VRT material. Articulation scores for words spoken with prosthetic obturation ranged between 92 and 98 per cent correct, suggesting that these patients spoke as intelligibly following maxillofacial prosthetic treatment as normal speakers.“> 3 Finally, it is important to note that the materials used to assess intelligibility of

94

Majid,

Weinberg,

and

Chalian

Words

Spoken

without

Words

Spoken

with

Prosthetic

Obturation

60 50 40 30

20 10 0 Prosthetic

Obturation

100 90 80 70

60 50 40 30

20 10 0

II S3

Word-Initial

Group

'6

Consonants

Fig. 8. Intelligibility scores (per cent correct) spoken with and without prosthetic obturation.

Word-Final

for word-initial

Average

Consonants

and word-final

cOnsOnants

consonant words permitted a comparison of word-initial vs. word-final consonants. A summary of such an analysis is shown in Fig. 8. A reduction in the intelligibility of both word-initial and word-final consonants followed maxillary surgery. On the average, the articulation scores for word-initial and word-final consonants were equivalent-about 60 per cent correct. Four speakers had slightly higher scores for word-initial consonants, while two subjects showed slightly better performance on word-final consonants. By comparison, all six speakers had nearly perfect intelligibility for both word-initial and word-final consonants following maxillofacial prosthetic treatment.

Volume Number

32 1

Speech ajter prosthetic

obturation

of dejects

95

DISCUSSION The principle objective of this project was to assess changes in the intelligibility of speech associated with surgery and prosthetic treatment of large, surgically acquired maxillary defects. Six patients who had undergone partial maxillary surgery for the removal of oral cancers were studied. In each patient, the surgical defects involved extensive resection of the hard palate and minimal excision of soft palate morphology. Hence, conclusions concerning the effects of surgery and subsequent dental rehabilitation apply only to patients with defects of the type described here. With respect to the surgical effect, all patients exhibited a significant reduction in the intelligibility of speech following surgery-that is, while speaking without prosthetic obturation of their surgical defects (Figs. 7 and 8). For the six patients studied here, average intelligibility was 62 per cent correct for CRT words and 58 per cent correct for VRT words. Since those patients had been normal speakers prior to surgery, it was assumed that they would have exhibited nearly perfect intelligibility for both CRT and VRT words at that time.2’ ‘. ’ Thus, maxillary surgery resulted in about a 35 to 40 per cent reduction in average intelligibility for both consonant and vowel types of speech in these subjects. The present data also highlight the variation in speech performance following ablative craniofacial surgery. For example, articulation scores for speech produced without prosthetic obturation ranged from about 40 to 80 per cent correct for both CRT and VRT words (Figs. 7 and 8). This wide variation in performance among patients might be attributed to differences in the extent and site of surgical resections and to differences in compensatory speech mechanisms employed by the speakers. A systematic study of specific factors responsible for the differences in average performance for this group of patients was not pursued in the present project, such a study represents a promising area of future research. With respect to the effect of dental treatment, all patients exhibited a significant increase in the intelligibility of speech following maxillofacial prosthetic rehabilitation. Prosthetic replacement of large, surgically acquired maxillary defects produced about a 35 per cent average increase in the intelligibility of both CRT and VRT words (Figs. 7 and 8). It is important to emphasize that none of the patients received any formal speech therapy before or after surgery. Hence, the dramatic improvement in speech must be attributed primarily to the dental treatment. From an intelligibility point of view, all six patients spoke as well as normal speakers following dental reconstruction. Thus, despite large intersubject differences in speech performance following surgery and in the face of marked variation in the length of time patients had been wearing their permanent prostheses (two months to five years), all speakers exhibited nearly perfect intelligibility for both CRT and VRT words following dental treatment. The range in posttreatment articulation scores among subjects was small, with mean values varying between 92 and 98 per cent correct. At the time this study was started, we were unable to locate any published research dealing with the measurement of speech intelligibility characteristics of patients who had undergone partial maxillary resection. In 1972, Kipfmueller and Lang” published an article describing the changes in speech intelligibility associated with maxillary surgery and subsequent prosthetic obturation of such acquired surgical defects. By coincidence, they also studied six patients; three were edentulous,

96

Majid,

Weinberg,

and

Chalian

and three had sufficient maxillary teeth following surgery to provide abutment sufjport for a prosthesis. Comparisons between the results of the Kipfmueller and Lang” and those of the present study are difficult to make because of differences in subjects, experimental design, and obturator construction. Moreover, Kipfmueller and Lang evaluated only word-initial consonant intelligibility’ and based their estimates on articulation scores calculated from listener responses to single 50 item word lists. Despite these differences, the work of Kipfmueller and Lang and the present work both provide experimental support for two important clinical observations. Namely, partial maxillary resection surgery is associated with a significant reduction in the ability to produce highly intelligible speech, and postsurgical rnaxillofacial dental treatment produces an equally dramatic increase in speech intelligibility for word-initial consonant rhyme-test words. The results of the present experiment show that partial maxillary resection surgery is also associated with a marked reduction in the intelligibility of word-final consonants and vovvels. Finally, the present data show that maxillofacial prosthetic treatment of the type described is associated with a restoration of highly intelligible speech for all types of speech stimuli. These ohservations suggest that the achievement of normal speech intelligibility represents a realistic dental treatment objective for patients with acquired defects of the type studied here. We acknowledge C. Shanks in various

the assistance of Harry aspects of this study.

Brittain,

Phillip

Wilson,

Richard

Scott,

and

James

References 1. 2.

3. 4. 5. 6. 7.

Chalian, V. A., Drane, J. B., and Standish, S. M.: Maxillofacial Prosthetics, Baltimort*, 1972, The Williams & Wilkins Company. House, A. S., Williams, C. E., Hecker, M. H. L., and Kryter, K. R.: Articulation Testin,? Methods: Consonantal Differentiation With a Closed Response, J. Acoust. Sot. Am. 37: 158-166, 1965. Horii, Y.: Specifying the Speech-to-Noise Ratio: Development and Evaluation of a Noise Ph.D. dissertation, Purdue University, 1969. With Speech-Envelope Characteristics, Eagen, J. P.: Articulation Testing Methods, Laryngoscope 58: 955-991, 1948. Majid, A. A.: Speech Intelligibility Characteristics of Patients With Partial Surgical Rrsection of the Maxilla, M.S.D. thesis, Indiana University School of Dentistry, 1973. Kipfmueller, L. J., and Lang, B. R.: Presurgical Maxillary Prosthesis: An Analysis of Speech Intelligibility, J. PROSTHET. DENT. 28: 620-624, 1972. Fairbanks, G.: A Test of Phonemic Differentiation: The Rhyme Test, J. Acoust. Sot. Am. 30: 596-600, 1958. INDIANA

1211

UNIVERSITY

W. MICHIGAN

INDIANAPOLIS,

IND.

SCHOOL ST.

46202

OF DENTISTRY