journal club vvs

8/2/2019 Journal Club Vvs

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Speech patterns ofedentulous patients andmorphology

of the palate in relation tophonetics


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An Introduction

In the production of speech sounds,the tongue contacts various portionsof the

teeth, the alveolar ridge, and the hardand soft palate.

When these structures are covered or

replaced by a denture, proprioceptivefeedback may be changed.Therefore,phonetics may be affected

by the presence of a denture.


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There are conflicting data on howdenture wearers achieve speechimprovement.

Allen stated that neglect of phoneticsin complete denture construction maybe

attributed to the fact that edentulouspatients tend to return to their normalspeech patterns after insertion of

dentures.


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This Study aims at toinvestigate: ( 1)The changes in the speech

patterns

of patients with new complete dentures

before and at various times afterinsertion

of the new dentures &

(2) any relationship between speechproduction and the palatal contour ofthe denture.


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CHANGES IN SPEECH PATTERNSOF EDENTULOUS PATIENTS WITH

NEW COMPLETE DENTURES AFTERVARIOUS TIME PERIODS :

Selection of subjects. Ten edentulouspatients wearing satisfactory newcomplete

upper and lower dentures were selected.


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All of these dentures had 14 artificialteeth in each dental arch. Fivesubjects were women and five were

men, having an average age of 49years. All were Caucasians withreasonably normal occlusions and oral

structures,and they all had approximately thesame square-tapering dental-arch

form.


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Test material.

Ten stimulus sentences were usedwith the consonants ch, j, sh, th, s, Z,

t, n, d, and 1 in initial, medial, and finalpositions in the words.


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these sounds are produced when thetongue contacts various parts of theteeth,the alveolar ridge, and the hard

palate of the maxillary denture. Examiners evaluated only those

sounds which had been recorded. The

recordings were made at four differenttime intervals.

Recording time order.


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The speech of each subject wasrecorded at the following times:

( 1) prior to the insertion of the newdentures,

(2) one hour after the insertion of

the new dentures,

(3) 24 hours after the insertion of the

new dentures, and (4)one week after the insertion of the

new dentures.


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Recording procedure.

The subject practiced reading the ten stimulus sentencestwo times each. The readings were then recorded foreach patient.

The recordings were made on tape at a speed of 7&1/2inches per second on a Sony Model T. C-350 recorder,*and a Sony F96 microphone was used.

The patients were instructed to monitor their level ofspeaking so that the tape recorders volume meter didnot peak into the distortion zone.


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The recordings made for each patient ateach of the four time sessions totaled

400 recorded sentences, which wereedited and randomized onto a master

tape. Forty combinations in random order were

made for each sentence spoken by theten patients at four different recording

sessions. Therefore, ten different master tapes

with ten different stimulus sentenceswere made to determine the intelligibility

of speech.


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Judging and rating.

A psychophysical method was usedfor evaluating the intelligibility of the

speech of the edentulous patients. Nineteen examiners were selected.

These examiners had been trained in

speech.


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The ten edited master tapes werepresented to these examinersindependently.

They evaluated each sentence on a 1 to

7 point scale. Sentences rated as 1 were the poorest

and as 7 were the best. Instructions and rating sheets were given

to all examiners to enable them toevaluate the tapes. The examiners wereunaware of the randomized order of thesentences and were asked to evaluate

only the quality of the speech.

ANALYSIS OF THE PALATAL CONTOURS OF


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ANALYSIS OF THE PALATAL CONTOURS OFPATIENTS WITH COMPLETEDENTITIONS AND OF THE MAXILLARY

COMPLETE DENTURES TESTED The ten dentulous subjects had at

least 14 teeth in each dental arch.

They had reasonably normal speech, occlusion,

anatomic tooth form, and oralstructures.

They also had square-tapering dental-arch form.


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Two diagnostic casts of the maxillary arch ofeach dentulous subject and the lingual

surface of the palate of the complete dentureof each edentulous patient were made foranalysis of palatal contour, making a total of40 diagnostic casts.

The three screws on the cast-supporting jigwere then adjusted until the three referencepoints on the cast made an even contact withthe stylus rod (Fig. 1).

The cast, while in the supporting jig, was then

placed into another mix of dental stone,making sure that all three screws contactedthe flat base. With this procedure the base ofthe cast parallel to a plane was determinedby the three reference points.


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Sectioning and cutting .

All sectioning was accomplished with the use of adental cast trimmer.* One of the casts was cut infrontal sections, and the others were cut in sagittalsections (Fig. 2).

Analysis of the palatal contour. It was assumedthat the palatal contours of the various sectionswould adapt for analysis to the parabolic quadraticequation

On the frontal sections, the X axis was determinedby the base of the cast, and the Y axis was drawn

through the midsagittal line of the cast. On the sagittal sections, the X axis was determined

by the base of the cast, and the Y axis wasconstructed through the gingival margin on thepalatal side of the left central and lateral incisor

teeth.


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On the frontal sections, curvature A starts at thelingual surface of the gingival margins of theteeth and terminates at the inflection with the Bcurvature. The B curvature starts at the inflectionwith the A curvature and terminates at the vertex

of B and C curvatures. Curvatures C and D arecorresponding curvatures to B and A,respectively.

On the sagittal sections, curvature E starts at thelingual surface of the gingival margin of the teeth

and terminates at the inflection with the Fcurvature. Curvature F starts at the inflection with the E

curvature and terminates at the distal end of thecast.


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Analytic formula.

The measurements were analyzed according to the

following mathematical formula by means ofcomputer analysis

y = ax + bx + c.

Three sets of (x, y) values as obtained from the

measurements (tracing paper)were substituted intothe equation, and then three sets of linearequations were made. Therefore, three unknowncoefficients (a, b, and c) in the above quadratic

equation can be solved simultaneously.


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After the a, b, and c values have beencalculated, the quadratic equation can

be analyzed as follows:

(1) a expresses the curvature of theparabola;

(2) Y =c - (b/4a) expresses the y

value at the vertex; (3) X = - (b/2a) expresses the x

value at the vertex.


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The inflection of the two parabolas canbe determined using the following

mathematical formulas :

Assuming that two quadraticequations inflect at a certain point,

their determinates be equal.


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Therefore:


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expresses the X value at the inflection.Now, if this X value is substituted into theabove equation, the Y value at the

inflection can be solved simultaneously.These data determine the curvature of thepalatal contours, to ascertain whether anydifference exists between the palatal

contours of the dentulous subjects and themaxillary dentures, and to measure thepalatal vault height and tooth height.


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RESULTS:


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RESULTS:Changes in speech patterns of

edentulous patients Nineteen examiners responses (a total

of 7,600 responses) were

unscrambled from the random orderarrangements. These rated scoreswere then tabulated on work sheets,and the means were computed for the19 listeners.


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The reliability of the judges washandled by an analysis of variance ina treatment-by-subject design with the

use of the Spearman-Brown method. The reliability of the 19 listeners was

at the 0.991 level. In other words, not

only did each judge rate with very highconsistency, but the judges were alsoconsistent among themselves.


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In Fig. 5 are the mean scores of the

responses given by the 19 listeners for allthe sounds spoken by each subject at thefour different recording sessions.

The F values for the time conditions arestatistically significant at the one per centlevel of confidence, as shown in Table II.


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The four conditions and each of the tensounds were treated by an analysis ofvariance in a treatment-by-treatment-by-subject design.

Fig. 5 shows that there was consistentprogressive improvement of intelligibility ofspeech sounds for all subjects with increasedlength of denture-wearing time. However,

each subject showed different degrees ofimprovement.

Neither the correlation between women andmen in the intelligibility of speech nor thecorrelation between age and intelligibility ofspeech of the patient was significant.


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the mean scores for each of the sounds: ch, sh,j, zh, s, .z, t, n, d, and 1. The F values for the sounds

were statistically significant at the one per centlevel of confidence. The summary of these

confidence scores is in Table II1 The z/z sound had the lowest rated intelligibility,

and the 1 sound had the highest ratedintelligibility as the mean for the four-time

recording sessions. The sh sound had the lowest intelligibility before

the subject wore a denture. After insertion of the denture, all sounds showed

an increase in intelligibility except the s sound,which stayed nearly the same.


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. The 45 possible comparisons (t tests)among the

ten sounds were analyzed.

The 22 combinations of sounds were

statistically significant at the one to five percent level of confidence. The speech soundsch, j,sh, zh, and s were significantly differentwhen compared to all of the other sounds.

This summary is in Table III. Acousticdistortions occurred more frequently in thech, j, h, zh, and s sounds than in the Z, t, n, d,and 1 sounds. The correlation between the

palatal vault height and speechintelli ibilit was not si nificant.


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Palatal contour

Sagittal sections. This study showed that a reverse curveexists in the sagittal sections of the casts of dentuloussubjects. This curve, starting at the lingual surface of thegingival margin of the incisor teeth, has a shallow inclinationand is convex.Then, at its inflection, the curve becomes

concave (Fig. 7). The inflection (junction of E and F curves) of this reverse

curve was 11 to 13 mm. behind the incisor teeth and 6 mm.superior to them, which is approximately in an imaginaryplane passing through the long axis of the cuspid teeth. This

area of the inflection has the steepest inclination. Snow and Allen pointed out that this convexity in the anterior

palatal region is important for producing the s and sh sounds.However, the curvature in the casts of the maxillary denturesstudied was either lacking or more shallow (Fig. 7).


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Frontal section. The frontal sections exhibited two types ofcurves. In the bicuspid region, there was just one continuousconcave curve from tooth to tooth on the dentulous subjects(Fig. 8).

This same type of curve was observed on the casts ofmaxillary dentures except that it was more shallow (Fig. 8). Inthe first and second molar sections, a double reverse curvewas noted from tooth to tooth.

The inflections of the first molar sections occurred medially2.29 mm. from the tooth and superiorly 3.22mm. from thetooth.

The inflections in the second molar sections were 3.52 mm.

medial and 4.38 mm. superior from the tooth.


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This means that the alveolopalatal tissuesbecame progressively thicker the moreposterior they were from the bicuspid teeth.The steepest inclination existed in the middlethird of the palate on either side, as shown in

Fig. 8. The majority of the maxillary dentureswere lacking the double reverse curve, andthe concave part in the center of the palatewas shallower.

Many authors state that the convexity of thealveolopalatal tissue in the molar areas isimportant for proper speech. It may be thatmore attention should be given to the contourof palates in dentures in order to improve

speech production.


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Palatal vault height.

The palatal vault height was greater inthe casts of dentitions than indentures.

The measurements of the palatal vaultheight are shown in Table IV. The


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mean difference between the height ofthe vaults in maxillary complete denturesand natural palates was 3.46 mm. in the

bicuspid section, 6.10 mm. in the firstmolar section, and 4.91 mm. in thesecond molar section.

The available tongue space was reduced

by the complete dentures. The lowestvault height in the bicuspid section was6.2 mm.and this patients speech

intelligibility was rated as one of the


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DISCUSSION:

Changes in speech patterns at fourrecording sessions. Intelligibility of thespeech of edentulous patients with

new complete dentures was tested atfour different time intervals. This studyshowed that these dentures had

palatal contours quite different thanthose palates of subjects with naturalteeth.


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. In spite of the faulty palatal contoursof the maxillary complete dentures,the results indicated that there was a

significant improvement in theintelligibility of the speech at each ofthe recording sessions in progression

with new complete dentures


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The interesting part of this study isthat most of the edentulous patientsshowed an improvement when the

denture was first inserted. That is, thepatients

were found to speak better

immediately after receiving the newdentures than without any teeth.


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The improvement of speech with theincreased length of time wearing thenew

dentures was probably a function ofthe feedback mechanism.

That is, the patient was better able to

feel the placement of his tongue andwas able to readjust his speechmechanism (tongue to palate) during

speech production.


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Bouchers stated that the adaptability

of the tongue to compensate forchanges is so great that the majorityof patients master tonguemanipulation for the production ofsound within a few weeks.

Thus, the insertion of a denture maycause a temporary change in the

articulation of the speech sounds,andadaptability of the tongue mayprogress slowly.


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Intelligibility changes of speech sounds andrelation of the palatal contour of completedentures. The results of this study showed thatthere is a difference in intelligibility of differentspeech sounds.

Acoustic distortions occurred more frequently inthe s, sh, ch, zh, and j sounds than in the z, t, n,d, and 1 sounds.

The zh sound had the poorest rating forintelligibility.


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1 sound had the highest ratedintelligibility.

This was found to be true when the

sounds were compared during each ofthe four time periods. However,intelligibility improved with theincreased length of time wearing the

new dentures for each speech soundexcept the s sound. Particularattention should be paid to the ssound.


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There are many factors involved inspeech production that must beconsidered in denture construction.

Most prosthodontists agree thatcorrect placement of artificial

teeth gives the best results in correctspeech. The tooth position of the

dentures in this study could not beobserved because pre-extractionrecords were not available.


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. However, the results showed that,when the sounds were made withoutthe dentures, the rh and j sounds hadthe lowest scores for intelligibility, butwhen

the denture was first inserted,intelligibility of these sounds improved

greatly. Therefore, positioning of the artificial

teeth in complete dentures should beconsidered an important factor ins eech roduction.


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The results of this study showed thatthere was a difference in the palatalcontour of the complete dentures and the

palates of the subjects with natural teeth. The greatest difference was on the

lingual surface beIow the gingival marginofthe teeth. After extraction of the natural

teeth, this area changes greatly, and it isdifficult to reproduce on the finisheddenture.


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The palatal contours of the casts ofnatural teeth showed a convex curvewhile the palates of dentures showed aconcave curve (Figs. 7 and 8).

The height of the teeth from the tip of thelingual cusp to the gingival margin wasgreater in the natural teeth than in thecomplete dentures. These areas areimportant in the articulation of theconsonants, especially the s, z, sh, zh,and j sounds


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The border surface of the tongue, actingas a blade,is used in the production ofthese sounds. Generally, the tongue isspread to touch the lingual surfaces of the

premolars and molars and thealveolopalatal surface

adjacent to them.

The tip of the tongue is used forproducing the fricative and affricativesounds. The airstream is forced betweenthe tongue and the palate.It is then

deflected over the upper edge of the


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Faulty acoustic effects of the s, sh, zh, j, and chsounds may result if the airstream escapes overone or both sides of the tongue, when the tonguetip is in contact with teeth or palate, or when thetongue tip cannot compress the air-streambetween the tongue and the palate.

Therefore, faulty palatal contours of dentures orchanges in the dental arch width due to incorrectpositioning of the artificial teeth may affect theintelligibility of these speech sounds.


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To obtain normal speech in dentureconstruction, Sears, Allen, andMehringer introduced a procedure todevelop a normal tongue-palatal pattern(palatography)in the wax maxillary trial denture.

However, observation of the palatogramsindicates that no two persons contact the

same area while pronouncing givenconsonants. Also, this is a staticrecording of the tongue duringarticulation of sounds. Analysis of thisinformation requires a highly developed

knowledge of phonetics.

SUMMARY AND


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SUMMARY ANDCONCLUSIONS Phonetics is one of the important factors in

complete denture construction.

Frequently, however, this factor is neglectedbecause of the adaptability of patients.

The need to consider phonetics is notrecognized in most instances until a patientcomplains of inability to produce certainsounds with the dentures. Usually, only a

small number of patients are thus troubled. To aid the dentist in minimizing these speech

problems, the adaptability of speechproduction of edentulous patients was tested.


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A psychophysical method was usedfor evaluating the speech of theedentulous patients with new

complete dentures. The palatal contours of the dentures

were analyzed and studied to

determine ifany relationship existed betweenpalatal contour and speechintelligibility Variations in speech


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Conclusion:

On the basis of analysis of the datacollected, the following conclusions weremade:

1. )Most of the patients showed speech

improvement when the dentures were first inserted.

2. )With increased length of time of

wearing the new dentures, the speechintelligibility was improved.

3. )The speech of patients can beimproved by experience with their new

dentures.


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4. Individual sounds showed differentlevels of speech intelligibility, and thislevel improves with the length of dentureusage.

5. Acoustic distortions occurred morefrequently in the s, sh, ch, zh, and jsounds than in the t, t, n, d, and 1sounds.

6. The s sound is a poor prognosticsound for intelligibility of speech.

7. Th palatal ridge formation (palatalcontour) of complete dentures will affectthe acoustic distortion of affricative andfricative sounds.


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Thankyou!

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