Phonetics in complete dentures./ dentistry course in india


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Phonetics in complete dentures./ dentistry course in india

  4. 4. INTRODUCTION "Speech is the use of systematized vocalization to express verbal symbols or words." (Sheridan: 1964) Speech is a very sophisticated autonomous and unconscious activity. Speech in matured man is a learned habitual neuromuscular pattern which makes use of anatomical structures designed primarily for respiration and
  5. 5. The development of the vocal sound into meaningful speech was one of the major accomplishments which enabled man to reach the pinnacle of the animal kingdom, and speech as the basic and fundamental means of communication became the corner­stone for the establishment and organization of society. In the highly complex international society of today, with the sophisticated systems for transmitting the voice,
  6. 6. the spoken word becomes increasingly important in establishing and maintaining a niche in the social structure. Today, man is judged not only by what he says, but equally by the way he says it. Proper speech is a reflection of education, careless speech is an imputation of slovenliness, and faulty speech is a handicap directly proportionate to the degree of speech incapability.
  7. 7. Phonetics – The science of sounds used in speech. Phonetic value – The character or quality of vocal cords
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  10. 10.
  11. 11.
  12. 12.
  13. 13. The epithelial lining of the larynx develops from the endoderm of the cranial end of the laryngotracheal tube. The cartilages of the larynx develop from the cartilages in the fourth and sixth pairs of pharyngeal arches. The laryngeal cartilages develop from mesenchyme that is derived from neuralcrest cells.
  14. 14. The mesenchyme at the cranial end of the laryngotracheal tube proliferates rapidly, producing paired arytenoid swellings. These swellings grow toward the tongue, converting the slit­like aperture ­ the primordial glottis ­ into a T­shaped laryngeal inlet and reducing the developing laryngeal lumen to a narrow slit. The laryngeal epithelium proliferates rapidly, resulting in temporary occlusion of the laryngeal lumen. Recanalization of the larynx occurs by the 10th week.
  15. 15. The laryngeal ventricles form during this recanalization process. These recesses are bounded by folds of mucous membrane that become the vocal folds (cords) and vestibular folds The epiglottis develops from the caudal part of the hypobranchial eminence, a prominence produced by proliferation of mesenchyme in the ventral ends of the third and fourth pharyngeal arches. The rostral part of this eminence forms the posterior third or pharyngeal part of the tongue.
  16. 16. Because the laryngeal muscles develop from myoblasts in the fourth and sixth pairs of pharyngeal arches, they are innervated by the laryngeal branch of the vagus nerves (CN X). Growth of the larynx and epiglottis is rapid during the first 3 years after birth. By this time the epiglottis reaches its adult form.
  17. 17. ANATOMY The larynx is a respiratory organ, set in the respiratory tract between the pharynx and trachea. Although phonation is important in man, the main function of the larynx is to provide a protective sphincter for the air passages. The larynx lies below the hyoid bone in the midline of the neck at the level of C 4­6 vertebrae.
  18. 18.
  19. 19.
  20. 20. SKELETON OF THE LARYNX The framework of the larynx consists of cartilages, liga­ments and membranes. There are three single cartilages (thyroid, cricoid and epiglottic) and three pairs of cartilages (arytenoid, corniculate and cuneiform). The ligaments and membranes are extrinsic (thyrohyoid membrane and cricotracheal, hyoepiglottic and thyroepiglottic ligaments) and intrinsic (quadrangular membrane and crico­ thyroid ligament). The vocal cords are the upper part of the cricothyroid ligament (cricovocal membrane).
  21. 21. The muscles that control the vocal folds are divided into two classes:­ a. Those with in the organ itself (intrinsic) b. Those that act upon it from out (extrinsic). The intrinsic muscles have two main functions:­ 1. To adduct and abduct the folds 2. To regulate the degree of their tension and length.
  22. 22. The muscle that open the rima glottidis are posterior Crico­arytenoids. They are attached to the posterior surfaces of the arytenoid and cricoid cartilages. Thus, they may rotate the arytenoid cartilages laterally and separate the true vocal cords. Closure of rima glottides is affected by the arytenoid and lateral Crico­arytenoid muscle. They rotate the arytenoid muscle is medially and causes the true vocal folds to be approximated
  23. 23. The arytenoids muscle extends from the posterior and lateral surfaces of one arytenoid cartilage to the corresponding surface of the other. These bring the arytenoids cartilage together, consequently narrowing the rima glottidis. The most important muscle used in lengthening and tensing the true vocal folds is the cricothyroid. The vocal folds are relaned and shortened by the thyroaryteniod muscle.
  24. 24. The extrinsic (accessory) muscles act upon the larynx as a whole, connecting the larynx with the hyoid bone, the sternum, the tongue and the pharynx. By means of these muscles, the larynx may be elevated, depressed and tilted.
  25. 25. Blood Supply Above the vocal folds blood is brought to the larynx by the superior laryngeal branch of the superior thyroid artery. This enters the piriform recess below the internal laryngeal nerve by piercing the thyrohyoid membrane The superior laryngeal veins accompany the artery and empty into the superior thyroid veins. The lower half of the larynx is supplied from the inferior laryngeal branch of the inferior thyroid artery; it accompanies the recurrent laryngeal nerve beneath the inferior constrictor of the pharynx. Venous return is by the inferior laryngeal veins to the inferior thyroid
  26. 26. Lymph drainage From the upper and lower halves of the larynx, lymphatics accompany the superior or inferior thyroid vessels and drain to the upper or lower groups of deep cervical nodes respectively. A few lymphatics pass through the cricothyroid membrane and drain initially to prelaryngeal and to pretracheal nodes.
  27. 27. Nerve supply All the muscles of the larynx are supplied by the recurrent laryngeal nerve except cricothyroid which is innervated by the external laryngeal nerve. The mucous membrane of the larynx above the level of the vocal folds is supplied by the internal laryngeal nerve; that of the folds and the larynx below them is supplied by the recurrent laryngeal nerve.
  28. 28. The sympathetic supply (vasoconstrictor) comes in with the superior and inferior laryngeal arteries from the middle and inferior cervical sympathetic ganglia.
  29. 29.
  30. 30.
  31. 31. MECHANISM OF VOICE PRODUCTION The pre­requisites for sound are a source of energy and a vibrator . The source of energy for the voice is air in the lungs. The vibrator for the voice are the vocal folds in the larynx. The larynx, pharynx, nasal cavity all act as cavity resonators to reinforce the original sound wave. This reinforcement is augmented by the change of shape and size of these cavities permitted by neuromuscular control.
  32. 32. Speech involves not only the respiratory system but also (1) specific speech nervous control centers in the cerebral cortex, (2) respiratory control centers of the brain, (3) the articulation and resonance structures of the mouth and nasal cavities. Speech is composed of two mechanical functions: (1)phonation, which is achieved by the larynx, (2) articulation, which is achieved by the structures of the mouth.
  33. 33. Phonation. The larynx is especially adapted to act as a vibrator. The vibrating element is the vocal folds, commonly called the vocal cords. The vocal folds protrude from the lateral walls of the larynx toward the center of the glottis; they are stretched and positioned by several specific muscles of the larynx itself. During normal breathing, the folds are wide open to allow easy passage of air. During phonation, the folds move together so that passage of air between them will cause vibration. The pitch of the vibration is determined mainly by the degree of stretch of the folds but also by how tightly the folds are approximated to one another and by the mass of their
  34. 34.
  35. 35. The three major organs of articulation are the lips, tongue, and soft palate The resonators include the mouth, the nose and associated nasal sinuses, the pharynx, and even the chest cavity.
  36. 36. PHYSIOLOGIC VALVES IN SPEECH PRODUCTION Speech mechanism includes three principal physiologic valves 1. Valve I , the glottis 2. Valve II, the palatopharangeal region 3. Valve III, the orifice of the mouth.
  38. 38. True vocal folds of larynx :­ The vibrating mechanism produces vocal tones, and the true vocal folds serve as a valve only in connection with speech sounds that have tone i.e., the voiced sounds other wise, the out going stream of air passes through the region of the vocal folds without interference as in normal breathing. The valve mechanical serves to modulate the outgoing breath stream in instance of voiced sounds only. It is a generator of sound waves which enables man to communicate at a distance as contrasted to the short distance through which one might communicate by whispering.
  39. 39. The larynx, containing the vocal folds that serve intermittently as value I during speech, is composed of three single cartilages and three pairs of cartilages. They are connected by ligaments and moved by muscles, the larynx has a mucous membrane lining that is continued superiorly with the pharynx and inferiorly with the trachea. The cartilages and muscles offer the means for adducting (approximating) and abducting (separating) the true vocal folds and for tensing them (shortening antero­posteriorly) and relaxing them (elongating antero­posteriorly).
  40. 40. When in a position of rest, as in quiet breathing, the free edges of the folds form an angular opening which has its apex located anteriorly and its base posteriorly the opening or aperture between them when they are not approximated is called rima glottidic.
  41. 41. When voice is desired, the folds are approximated, and air is pushed against them from below with sufficient force to blow the edges of these elastic folds apart. The overload of air pressure is momentarily spent. Tension restores the folds to a closed position. This cycle is repeated. The acoustic output is called voice.
  42. 42.
  43. 43. PHYSIOLOGIC VALVE 11:­ Palatopharangeal region:­The pharynx is made up primarily of a constrictor band of broad, flat muscles inserting into a median raphe along its posterior wall. The pharynx may be divided arbitrarily into three parts:­ 1.The nasal pharynx 2.The oral pharynx 3.The laryngeal pharynx
  44. 44. 1.The nasal pharynx is a continuation of nasal cavity posteriorly; it is bounded inferiorly by the soft palate and terminates along the posterior pharyngeal wall near the atlas (1 st cervical vertebra). It's only function is respiratory. 2.The oral pharynx is a continuation, inferiorly, of the nasal pharynx to the laryngeal pharynx, i.e. about the level of hyoid bone. It's function are respiratory and digestive
  45. 45. 3. The laryngeal pharynx is the inferior portions of the pharynx. It extends inferiorly from the oral pharynx and terminates in the esophagus at about the level of the VIth cervical vertebra. Its function is strictly digestive. The palato­pharangeal value is located in the region in which the respiratory and digestive tracts cross each other (pharyngeal Isthmus).
  46. 46. Both in the act of swallowing and in speech, this valve divide the pharynx into naso­pharyngeal and oro­pharyngeal cavities. The principal closure is affected by movement of the soft palate into contact with the posterior wall of the pharynx
  47. 47. PHYSIOLOGIC VALVE 111:­ The Mouth:­ The mouth is a complicated valve, capable of making many changes, both in capacity and in size of the orifices. It is modified by many articulators, the chief one being the tongue. The three physiologic valves serve to form a number of more specific articulatory valves, such as:­ 1. Mandibular lip against the maxillary lip. 2. Mandibular lip against the maxillary teeth 3. Tip of the tongue against the alveolar ridge etc.
  49. 49. 1. RESPIRATION The speech process is initiated by the energy inherent in a stream of air. In normal speech, the respiratory apparatus provides, during exhalation, a continuous stream of air with sufficient volume and pressure, under adequate voluntary control, for phonation. The stream of air is modified in its course from the lungs by the maxillofacial structures and gives rise to the sound symbols which we recognize as speech.
  50. 50. 2. PHONATION When air leaves the lungs, it passes through the larynx, whose true vocal folds modify the stream. The true vocal folds, by opposing each other with different degrees of tension and space, create a slit like aperture of varying size and contour. The folds, by creating resistance to the stream of air, set up a sequence of laryngeal sound waves with characteristic pitch and intensity. These laryngeal sounds provide the basis for the organization of
  51. 51. 3. RESONATION The sound waves produced at the true vocal folds are still far from being the finished product that we hear in speech. It is the resonators that give the characteristic quality to the voice. The resonating structures are the air sinuses, organ surfaces and cavities, such as the pharynx, oral cavity, nasal cavity, and chest wall. The resonating structures contribute no energy to the stream of air; they act to conserve and concentrate the energy already present in the laryngeal tone, rather than to let it dissipate into the tissues. However, the resonated laryngeal tone still is not
  52. 52. 4.ARTICULATION It is the function of the articulatory mechanism to break up and modify the laryngeal tones and to create new sounds within the oral cavity. So the final action of the articulatory apparatus is to articulate, that is to join in a fluid sequence all the sounds which have been synthesized into symbols. Without the articulatory capacity, the sounds produced would be only of variable pitch, volume, and quality, like a vowel sound.
  53. 53. 5. NEURAL INTEGRATION Speech is integrated by the central nervous system both at the peripheral and central level. Speech is a learned function, and adequate hearing and vision and a normal nervous system are required for its full development. When the speech function comes into conflict with other vital functions of the maxillofacial structures, it is speech that suffers.
  54. 54. 6. AUDITION Audition, or the ability to receive acoustic signals, is vital for normal speech. Hearing permits receptions and interpretation of acoustic signals and allows the speaker to monitor and control speech output. Compromised hearing can preclude accurate feedback and hence, affect speech. Speech development and subsequent speech therapy is hampered in patient with hearing impairments.
  56. 56. The surd is any voiceless sound and is produced by separation of the vocal folds (glottis open) with no marginal vibration. The sound is made by frictions of the air stream as it posses through the appropriate cavities; the initial 'h' sound as in huh and the voiceless sibilants, z, sh and zh pronounced initially are examples.
  57. 57. The sonants are voiced sounds and include all vowels and vowel like sounds. They are produced by vibration of some portions of vocal folds to establish the original sound wave, which is augmented by cavity resonations. The vowels require minimum articulation
  58. 58. Consonants are articulated speech sounds, and all require articulation to impede, constrict, divert, or stop the air stream at the proper place and time to produce the desired sound.
  59. 59. ENGLISH CONSONANTS Stops Fricatives Affricatives Diversions
  60. 60. Stops:­ Are characterized by stoppage and sudden release of air stream and require complete occlusion of the articulators involved; the plosives P and B are produced by closure of the lips to permit momentary build up of the air stream, followed by a sudden explosive release, and t and d are produced by tongue contacting the hard palate to stop the air stream before suddenly releasing it; and the K sounds are produced by tongue and soft palate closing the oral cavity at the same time the soft palate and pharynx close the nasal cavity to stop the air stream prior to plosive release.
  61. 61. STOPS
  62. 62. Fricatives:­ Are produced by the air stream being forced through loosely closed articulators or a narrow passageway. For the labiodentals f and v, the lower lip articulates with the maxillary anterior teeth to constrict the air stream. The linguo­dental ‘th’ is produced by incomplete articulation of tongue, lip maxillary incisors to construct the air stream. The sibilants s, z, zh, sh are produced by tongue blade articulating with the lateral aspects of the hard palate, permitting the air stream to be forced through the groove created in the tongue
  63. 63. FRICATIVES
  64. 64. Affricatives:­ j and ch are produced by a combination of stop and friction, accomplished by articulation of the tongue and anterior hard palate.
  65. 65. 4. Diversions:­ Of the air stream is characterized by stoppage at one point to permit escape at another. The nasal m is produced by the lips occluding to seal the oral cavity and permit emission through the nose. The nasal n is produced by articulation of the tongue and hard palate closing the oral cavity while the sound escapes through the nasal cavity.
  66. 66. The nasal ng is produced by the tongue and soft palate closing off the oral cavity to permit nasal emission. For the lateral "I", the tongue apex occludes the anterior portion of the oral cavity while sound escapes through the lateral portions.
  67. 67. ‘M’ , ‘N’ Sound
  68. 68. ENGLISH CONSONANTS THEIR POSITION AND MODE OF PRODUCTION The production of English consonants and involve six valves below:­ 1. Bilabial 2. Labiodental 3. Linguodental 4. Lingeoalveolar 5. Linguopalatal 6. Linguovelar Out of the above six valves five valves are affected by teeth position
  69. 69. Bilabial Sounds: ­ The sounds b, p and m are made by contact of the lips. Insufficient support of lips by teeth and / or denture base can cause these sounds to be defective. Therefore, the anterior­posterior position of the anterior teeth and the thickness of the labial flange can affect the production of these sounds like wise an incorrect vertical dimension of occlusion or teeth positioning hindering proper lip closure, might influence these
  70. 70. Labio­dental Sounds: ­ The labio­dental sounds f and v are made between the upper incisors and the labio­ lingual center to the posterior third of the lower lip. If the upper anterior teeth are too short (set too high up), the V sound will be more like an 'f. If they are too long (set too far down), the f will sound more like a v. If upper teeth touch the labial side of the lower lip while these sounds are made, the upper teeth are too far back in the mouth.
  71. 71. In this situation, the relationship of the inside of the lower lip to the labial surfaces of the teeth should be observed while the patient is speaking. If the lower lip drops away from the lower teeth during speech, the lower anterior teeth are most probably too far back in the mouth. If, on the other hand, imprints of the labial surfaces of the lower anterior teeth are made in the mucous membrane of the lower lip, or if the lower lip tends to raise the lower denture, are probably too far forward,
  72. 72. and this means that the upper teeth are also too far forward. If the upper anterior teeth are set too far back in the mouth, they will contact the lingual side of the lower lip when f and v sounds are made. This may also occur if the lower anterior teeth are too far forward in relation to the lower residual ridge.
  73. 73. Linguodental Sounds:­ Dental sounds (eg. Th) are made with the tip of the tongue extending slightly between the upper and lower anterior teeth. This sound is actually made closer to the alveolus (the ridge) than to the tip of the teeth. Careful observation of the amount of tongue that can be seen with the words ­ this, that, these and those will provide information as to the labio­lingual position of the anterior teeth.
  74. 74. If about 3mm of the tip of the tongue is not visible, the anterior teeth are probably too far forward, or there may be an excessive vertical overlap that does not allow sufficient space for the tongue to protrude between the anterior teeth. If more than 6mm of the tongue extends out between the teeth when such sounds are made, the teeth are probably too lingual.
  75. 75. Linguoalveolar Sounds:­ Alveolar sounds (eg. t, d, s, z, v & 1) are made with the valve formed by contact of the tip of the tongue with the most anterior part of the palate (the alveolus) or the lingual sides of the anterior teeth. The sibilants (sharp sounds) s, z, sh, ch & j (with ch & j being affricatives) are alveolar sounds, because the tongue and alveolus forms the controlling valve. The important observations when these sounds are produced are the relationship of the anterior teeth to each other.
  76. 76. The upper and lower incisors should approach end to end but not touch. A failure of the incisal edge to approach exactly end to end indicates a possible error in the horizontal overlap of the anterior teeth.
  77. 77. ‘Sh’ sound
  78. 78. THE S SOUND Its articulation is mainly influenced by the teeth and palatal part of the maxillary prosthesis. Clinical experience suggests that s and t can cause most problems in a prosthodontic context. In nearly all languages of the world, S is a common speech sound. The inter individual variation in articulatory details may be great due to individual variation in teeth, palate, lower jaw and tongue shape and size. However, the following phonetic properties are common to all s sounds.
  79. 79.
  80. 80. Linguopalatal and Articulatory characteristics :­ I. The tip of the tongue is placed far forward, coming but never touching the upper front incisors. II. The sagittal groove is made in the upper front part of the tongue, with a small cross sectional area III. The tongue dorsum is flat. IV. Normally, the mandible will move forward and upward, with the teeth almost in contact.
  81. 81. Acoustic characteristics The comparatively strong sound energy is concentrated to a high frequency range, with a steep energy cut off at about 3-4 kHz. Auditory characteristics I. The sound is fairly loud, with a light, sibilant (sharp) quality. The S sound can be considered dental and alveolar speech sounds because they are produced equally well with too different tongue positions, but there can be some variations even behind the
  82. 82. Most people make the S sound with the tip of the tongue against the alveolus in the area of the rugae, but with a small space for air to escape between the tongue and alveolus. The tongue's anterior dorsum forms a narrow groove near the midline, with a cross section of about 10 mm2 . The size and shape of this small space will determine the quality of the sound. Part of the sibilant sound is generated when the teeth are being hit by a concentrated air jet.
  83. 83. If the opening is too small, a whistle will result. If the space is too broad and thin, the S sound will be developed as sh, somewhat like a lisp. The frequent cause of undesired whistles with dentures is a posterior arch form that is too narrow. Creation of a sharp s requires accuracy of the neuromuscular control system, for the creation of the groove and directioning of the air jet. Even small deviations of only 1mm will influence the quality.
  84. 84. Linguovelar sounds:- The truly palatal sounds (example: year, she and onion) present less of a problem for dentures. The velar sounds (k, g and ng) have no effect on dentures, except when the posterior palatal seal extension encroaches on the soft palate.
  86. 86. 1. The vowel sounds – These sounds are produced by a continuous air stream passing through the oral cavity which is in the form of a single chamber. All vowel sounds involve the tongue having a convex configuration. The position of the hump of the tongue in relation to the hard and soft palates determines the quality of the sound. The tip of the tongue, in all the vowel sounds, lies on the floor of the mouth either in contact with or close to the lingual surfaces of the lower anterior teeth and gums.
  87. 87. The application of this in denture construction is that the1ower anterior teeth should be set so that they do not impede the tongue positioning for these sounds; i.e. they should not be set lingual to the alveolar ridge. The upper denture base must be kept thin, and the posterior should merge into the soft tissue in order to avoid irritating the dorsum of the tongue, which might occur if this surface of the denture were allowed to remain thick and square- edged.
  88. 88. Denture thickness and peripheral outline One of the reasons for loss of tone and incorrect articulation of speech is the decrease of air volume and loss of tongue space in the oral cavity resulting from unduly thick denture bases. The periphery of the denture must not be over-extended so as to encroach upon the movable tissues, since the depth of the sulci will vary with the movements of the tongue, lips and cheeks during the production of speech sounds. Any interference with the freedom of these movements may result in indistinct speech, especially if the function of the lips is in any way
  89. 89. Most important is the thickness of the denture base covering the centre of the palate, for here no loss of natural tissue has occurred, and the base reduces the amount of tongue space and the oral air volume. The production of the palatolingual group of sounds involves contact between the tongue, and either the palate, the alveolar process, or the teeth. With the consonants T and D, the tongue makes firm contact with the anterior part of the hard palate, and is suddenly drawn downwards, producing an explosive sound; any thickening of the denture base in this region may cause incorrect formation of these sounds..
  90. 90. When producing the S, C (soft), Z, R and L consonant sounds, contact occurs between the tongue and the most anterior part of the hard palate, including the lingual surfaces of the upper and lower incisors to a slight degree. In the case of the S, C (soft) and Z sounds, a slit- like channel is formed between the tongue and palate through which the air hisses. If artificial rugae are too pronounced, or the denture base too thick in this area, the air channel will be obstructed and a noticeable lisp may occur as a result.
  91. 91. To produce the Ch and J sounds the tongue is pressed against a larger area of the hard palate, and in addition makes contact with the upper alveolar process, bringing about the explosive effect by rapidly breaking the seal thus formed. The Sh sound is similar in formation, but the air is allowed to escape between the tongue and palate without any explosive effect, and if the palate is too thick in the region of the rugae, it may impair in the production of these
  92. 92. Vertical dimension The formation of the bilabials, P, B and M requires that the lips make contact to check the air stream. With P and B, the lips part quite forcibly so that the resultant sound is produced with an explosive effect, whereas in the M sound lip contact is passive. For this reason M can be used as an aid in obtaining the correct vertical height since a strained appearance during lip contact, or the inability to make contact, indicates that the record blocks are occluding
  93. 93. With the C (soft), S and Z sounds the teeth come very close together, and more especially so in the case of Ch and J; if the vertical dimension is excessive, the dentures will actually make contact as these consonants are formed, and the patient will most likely complain of the teeth clicking together.
  94. 94. Occlusal plane The labiodentals, F and V are produced by the air stream being forced through a narrow gap between the lower lip and the incisal edges of the upper anterior teeth. If the occlusal plane is set too high the correct positioning of the lower lip may be difficult. If, on the other hand, the plane is too low, the lip will overlap the labial surfaces of the upper teeth to a greater extent than is required for normal phonation and the sound might be affected.
  95. 95. Anteroposterior position of the incisors In setting the upper anterior teeth, consideration of their labiopalatal position is necessary for the correct formation of the labiodentals F and V. If they are placed too far palatally the contact of the lower lip with the incisal and labial surfaces may be difficult, as the lip will tend to pass outside the teeth; the appearance usually prevents the dentist from setting these teeth forward of their natural position.
  96. 96. If the anterior teeth are placed too far back some effect may be noticed on the quality of the linguopalatals S. C (soft) and Z, resulting in a lisp due to the tongue making contact with the teeth prematurely. The tongue will more readily accommodate itself to anteroposterior errors in the setting of the teeth than to vertical errors.
  97. 97. Post-dam area Errors of construction in this region involve the vowels U and a and the palatolingual consonants K, NG, G and C (hard). In the latter group the air blast is checked by the base of the tongue being raised upwards and backwards to make contact with the soft palate. A denture which has a thick base in the post dam area, or a posterior edge finished square instead of chamfered, will probably irritate the dorsum of the tongue, impeeding speech and possibly producing a feeling of
  98. 98. Indirectly, the postdam seal influences articulation of speech, for if it is inadequate the denture may become unseated during the formation of those sounds that have a explosive effect, requiring the sudden repositioning of the tongue to control and stabilize the denture; this applies particularly to singers. Speech is usually of poor quality in those individuals whose Upper denture has become so loose that it is held in position mainly by means of tongue pressure against the palate. Careful observation will show that the denture, in such cases, rises and falls with tongue movements during speech.
  99. 99.
  100. 100. Width of dental arch If the teeth are set to an arch which is too narrow the tongue will be cramped, thus affecting the size and shape of the air channel; this results in faulty articulation of consonants such as T, D, S, N, K, C, where the lateral margins of the tongue make; contact with the palatal surfaces of the upper posterior teeth. Every endeavor should be made, consistent with general principles of denture design, to place the lingual and palatal surfaces of the artificial teeth in the position previously occupied by the natural dentition.
  101. 101. Relationship of the upper and lower anterior teeth The chief concern is that of the S sound which requires near contact of the upper and lower incisors so that the air stream is allowed to escape through a slight opening between the teeth. In abnormal protrusive and retrusive jaw relationships, some difficulty may be experienced in the formation of this sound, and it will probably necessitate adjustment of the upper and lower anterior teeth anteroposteriorly so that approximation can be brought about successfully. The consonants Ch, J and Z require a similar air channel in their formation.
  103. 103. Speaking space The mandible moves vertically and anteroposteriorly during speech so that the lower teeth invade the freeway. space. Therefore some patients need more freeway space than others depending on the range of mandibular movement during speech. The closest speaking space is the space between the occlusal surfaces of the teeth when the mandible is elevated to the maximum extent during speech. There should be at least 1 mm of closest speaking space in all complete dentures. It should be emphasized that the freeway space is a resting measurement, while the closest speaking space is a dynamic
  104. 104. The large overjet in Angle’s Class II, division I. patients should be reproduced in the denture in order to give room for the anteroposterior movement of the mandible during speech. In this sense the overjet might be considered ‘ horizontal freeway space’, without which the patient would have considerable difficulty in wearing dentures.
  105. 105. A useful phonetic check for correct height is to ask the patient to say a sibilant word such as 'Mississippi', with the record blocks in the mouth. If the height is excessive the word will not be pronounced clearly and the blocks will contact during the 'ss' sounds. If the height is correct, the occlusal surfaces of the rims will be slightly apart during the 'ss' sounds. If the patient does not pronounce the word clearly, and no contact can be detected during the 'ss' sounds, it is likely that the tongue space is restricted by the record blocks, and the wax should be cut away on the lingual sides of the upper and lower rims until a clearer pronunciation is
  106. 106. ‘S’ Sound ‘N’ Sound
  107. 107. AE Sound
  108. 108.
  109. 109.
  110. 110.
  111. 111.
  112. 112.
  113. 113.
  114. 114.
  115. 115.
  116. 116. TRY IN – STAGE The wax trial dentures are prepared for the purpose of foretelling the appearance of the finished dentures and providing the opportunity to make any desired changes. Phonetic tests might be made first, fol1owed by a check of overlaps, occlusions, posterior palatal seal, facial contours, and size, form, color, and arrangement of the teeth. The final step is to ask the patient's approval. It is well to make the phonetic tests early in the routine, for when the patient's attention is concentrated on the speech sounds, his facial appearance is more likely to be natural than, when his attention is concentrated on
  117. 117. Because some speech faults are a consequence of poor retention of the bases, before any decisions are made the bases have to be stabilized, if necessary by means of a denture adhesive. When the mechanical and esthetic factors are correct, the phonetic factors seldom offer a problem. However, they should be checked.
  118. 118. Although the average patient is capable of making considerable muscular adaptation to altered tooth position and palate formation in order to produce speech sounds, we should not impose upon him the burden of acquiring new skills in enunciation. Furthermore, there are deviations in tooth position and palate formation beyond which it becomes impossible for the patient to accommodate himself.
  119. 119. Before speech begins, the mandible hangs loosely in rest relation. Just as occluding relation is a point of reference for the discussion of the mechanical problems, the rest relation is a point of reference for the discussion of phonetic problems. The position of rest relation is merely the habitual position of the mandible when not in use. Some of the speech sounds are made without much dependence on mandibular relation or tooth positions, whereas others depend largely on these factors. Strictly speaking, it is the position of the lower teeth rather than the position of the mandible which is important in the production of the various
  120. 120. By noting the habitual protrusion of the mandible as the patient attempts to produce some of the sounds, it is possible to check on the relation of the teeth to the other structures and change their positions if necessary in order to make them conform to the habitual speaking movements.
  121. 121. ‘F’ sound ‘V’ sound
  122. 122. ‘S’ sound
  123. 123. Posterior border of the denture- when the patient says ‘ah’, the junction of the fixed and movable palate is established and therein determines within limits the posterior extension of the dentures. Vertical dimension with the correctly trimmed maxillary occlusal rim place. The mandibular rim is trimmed to produce a space of 1mm when the patient says ‘s’. Height of the anterior teeth and thus the occlusal plane – using ‘f’ , ‘v’
  124. 124. Overjet – by using the ‘s’ sound Labiolingual position of the lower anteriors – ‘s’ Thickness of the anterior region of the palate - ‘t’ Thickness of the postdam – ‘g’
  125. 125. The channel in the tongue does not always lie in the exact center of the palate. Its location is not a matter of any practical consequence so long as the sounds are produced satisfactorily. When the sibilants offer difficulty, however, the lateral deviation of the channel should be determined, for a lack of sufficient depth in the tongue channel may be compensated for by making a channel in the denture base.
  126. 126. The location of the aperture through, which the air escapes is especially important in the case of lisping, since the necessary sagittal groove in the denture base must be placed opposite the channel in the tongue. If no channel at all exists in the patient's tongue, as in the case of some patients who lisp, a suitable channel is cut in the denture base at the median line.
  127. 127. The phonetics test can be used to check on the mechanics and even the esthetics of a denture. If while speaking, the patient carries the lower incisors in front of the upper ones, the horizontal overlap is probably not great enough for good mechanics or for the best appearance. If the ‘f’ and ‘v’ sounds offer difficulty, the upper incisal edges are probably far back or too short to appear best. If the opposing teeth touch during speech, the degree of jaw separation is too great.
  129. 129. When complete dentures are worn for the first time there is always some temporary alteration in speech owing to the thickness of the denture covering the palate, necessitating slightly altered positions of the tongue. Patients usually adapt readily to moderate changes in denture shape, and problems with speech which are apparent at the delivery stage are not often present at the review.
  130. 130. This is only a temporary inconvenience that can be most rapidly overcome by the patient reading aloud. Adaptation occurs rapidly over the first few days, but if distortions of speech persist after 30 days a change to the denture has to be made. However, that adaptation of speech patterns back to normal is prolonged when the patient has a hearing impediment, and not all patients will admit to such a disability.
  131. 131. A complaint of general speech can be associated with  Unfamiliarity with denture contour Too great vertical dimension Incorrectly positioned anterior teeth History of speech difficulties Interocclusal space Too low an occlusal plane Decreased tongue space.
  132. 132. The length, form and thickness of the lower lingual flange are important consideration in speech. Usually, patients with a low index of neuromuscular skill experience difficulty in speaking with artificial teeth. These patients do better with a lingual flange that does not extend below the mylohyoid ridge, nor posteriorly into the retroalveolar space. The thinnest, shortest snuggest lingual flange possible will aid their speech. However, the demands of retention may
  133. 133. TONGUE SPACE Restriction of the tongue space may give rise to the following complaints: (1)the patient feels that the dentures are a 'mouthful'; (2) the patient has difficulty in speaking; (3) the lower denture feels loose all the time; (4) the tip or sides of the tongue feel sore.
  134. 134. The provision of adequate tongue space in complete dentures is of the greatest importance for the comfort of the patient. Tongue space is most likely to be restricted anteriorly by the setting of the upper incisors in the wrong relationship to the incisive papilla, and pos-teriorly by the setting of the upper posterior teeth 'on the ridge' and the lower posterior teeth lingual to the ridge. If the requirements of occlusal balance make it necessary to have a steep compensating curve or a large angle of the plane of orientation,
  135. 135. the tongue cannot easily overlap the lower molars to stabilize the lower denture. In these cases it is necessary to leave off the second molar, so that an adequate posterior shelf is provided distal to the first molar. This posterior shelf should be at least 1 cm in length from the distal surface of the first molar to the posterior border of the denture. It provides space for the thick posterior part of the tongue, which can rest upon it and stabilize the denture.
  136. 136. Difficulty with speech, is often associated with the placement of the anterior teeth on the ridge instead of in front of it. The anterior tooth position can be very quickly checked by measuring from the middle of the incisive papilla depression, on the fitting surface of the denture, to the labial surfaces of the incisors. The horizontal distance between these two points should be approximately 1 cm. If it is less than 7 mm it is safe to assume that there is restriction of the anterior part of the tongue space.
  137. 137. PATIENT’S COMPLAINT CAUSES OF COMPLAINT Whistle on ‘s’ sounds Too narrow an air space on the anterior part of the palate Lisp on ‘s’ sounds Too broad an air space on the anterior part of the palate ‘Th’ and ‘t’ sounds indistinct Inadequate interocclusal distance ‘T’ sounds like ‘th’ Upper anterior teeth too far lingual ‘F’ and ‘v’ sounds indistinct Improper position of upper anterior teeth either vertically or horizontally
  139. 139. Are prominent rugae and glossy tongue surfaces on artificial dentures to be desired? Luzerne G Jordan JPD 1953; 4: 52-53 Matte or non glossy surfaces on upper denture especially is much more acceptable to patients than a glossy surface. Improve tongue comfort, but also aids materially in phonetics because the tongue is able to obtain a degree of traction on the denture surface, which is similar to that obtained when the tongue is rubbed against the mucosa. There is some evidence that rugae would improve phonetics done by carving interrugae grooves on the tongue surface of the denture over the areas where the grooves exist in the mouth.
  140. 140. The speaking method in measuring vertical dimension Meyer M Silverman JPD1953;3:193-199 He concluded that the speaking method of measuring vertical dimension is a physiologic phonetic method which measures V.D. by mean of the closet speaking space. This space is measured before the loss of the remaining natural teeth to give us the patient natural V.D. which can be recorded and used at later dates. Closest speaking space should be reproduced in full dentures as in the natural dentition. This space is also the means of proving that , VD must not be
  141. 141. Improved phonetics in denture construction Leslie R Allen JPD1958;8:753-763 He concluded that to develop a normal S & SH tongue palatal pattern in the maxillary trial base, it is usually necessary to thicken the area outlined by the palatogram. In most cases, it is necessary to thicken the area of the incisive papilla to prevent the jet of air emitted by the median sulcus of the tongue from escaping towards the vault. It was found that building the tongue palatal contact area to normal and thickening the area of the incisive papilla facilitated proper communication and eliminates much of the post insertion practice
  142. 142. A study of phonetic changes in edentulous patients following complete denture treatment. Joseph G Agnello JPD 1972;27:133-139 Words spoken in edentulous state were compared with words spoken at different stages of the denture wear. The ‘s’, ‘sh’ showed improvement however individual speech sounds developed differently. The voiced ‘th’ sound did not show any general improvement.
  143. 143. Phonetics and swallowing to determine palatal contour of dentures. Francis W Shaffer Robert A Kutz JPD 1972;28:360-362 Technique described by Lott and Levin for forming the palatal surface of dentures. It is a modification that utilizes tin foil on the cast prior to adding soft wax on the palatal surface of the trial denture base and then allows the patients tongue to mold the soft wax during speech and swallowing.
  144. 144.
  145. 145.
  146. 146.
  147. 147. Let ‘s’ be your guide Earl Pound JPD 1977:38;482-489 Establishing vertical dimension of occlusion based upon the fact that the body of the mandible assumes an easily recordable, repetitive horizontal and vertical position when the patient is at the ‘s’ position during speech. This controlled method of developing vertical dimension correlates the posterior speaking space with the placement of the upper and lower anterior teeth when set to a phonetic standard. This permits the development of a dependable vertical dimension of occlusion for most patients and also serve as a guide for the more difficult to treat class II and tongue thrusting
  148. 148. Palatogram assessment of maxillary complete dentures Farley DW, Jones JD, Cronin RJ. J Prosthodont 1998 Jun;7:84-90) presented a review of the mechanics of speech as well as common speech problems encountered with a removable maxillary prosthesis. The use of a palatogram to aid the clinician in the assessment and resolution of speech problems associated with a maxillary denture was demonstrated
  149. 149. Clinical rest and closest speech position in the determination of occlusal vertical dimension Seifert E, Runte C, Riebandt M, Lamprecht - Dinnesen A, Bollmann F J Oral Rehabil 2000;27:714-719 They concluded that variations of thickness and or volume of dentures and of the vertical and horizontal dimension of occlusion may result in unpredictable audible changes to the voice. Patients should be informed about possible effects of modified or new dentures on their
  150. 150. Spectral analysis of ‘s’ sound with changing angulation of the maxillary central incisor Runte C, Tawana D, Dirksen D, Runte B, Lamprecht-Dinnesen A, Bollmann F, Seifert E, Danesh G IJP 2002;15: 254-258 Concluded that the maxillary incisor position influences /s/ sound production. Displacement of the maxillary incisors must be considered a cause of immediate changes in /s/ sound distortion. Therefore, denture teeth should be placed in the original tooth position as accurately as possible. Results also indicate that neuromuscular reactions are more important for initial speech sound distortions than are aerodynamic changes in the anterior speech sound-producing areas.
  151. 151. SUMMARY Clarity of speech ie the articulation of sound, is an important oral function and its relationship to denture construction has been clearly demonstrated. The fact that the neuromuscular pathway for speech remain for a period of time after the teeth are lost is relevant. The aim of complete denture design must be, therefore to construct denture that will be in harmony with the existing pathway and not relay on the patient adaptive capabilities to tolerate new ones. Any change in the shape of the articulation tract can lead to errors in articulation and certain sounds may be used to identify these
  152. 152. CONCLUSION Speech difficulties as sequelae of oral rehabilitation with complete dentures are generally a transient problem. When encountered the difficulties may not be easily solved. Therefore efforts should be made to avoid them by pretreatment records or assessment of speech and provision of information to patients about likely initial deviation from normal speech, immediately following oral rehabilitation.
  153. 153. If persistent difficulties to pronounce certain sounds or other speech disorders persist for more than 2 to 4 weeks, the following protocol is recommended - 1. If the patient has the previous complete denture experience, compare the new set with the old one to diagnose possible design differences of significance for speech production. 2. Make the necessary modifications; soft wax might be helpful. 3. Have the patient's hearing checked. An auditory deficit will prolong the adaptation period and render it more difficult 4. If the reported perceived problem cannot be resolved by dental methods, the patient should be referred to speech
  154. 154. Speech has been shown to be an integral part of denture design and its value should not be overlooked.
  158. 158. Are prominent rugae and glossy tongue surfaces on artificial dentures to be desired? Luzerne G Jordan JPD 1953; 4: 52-53 The speaking method in measuring vertical dimension Meyer M Silverman JPD1953;3:193-199 A study of phonetic changes in edentulous patients following complete denture treatment. Joseph G Agnello JPD 1972;27:133-139 Phonetics and swallowing to determine palatal contour of dentures. Francis W Shaffer Robert A Kutz JPD 1972;28:360-362
  159. 159. Let ‘s’ be your guide Earl Pound JPD 1977:38;482-489 Palatogram assessment of maxillary complete dentures Farley DW, Jones JD, Cronin RJ. J Prosthodont 1998 Jun;7:84-90 Clinical rest and closest speech position in the determination of occlusal vertical dimension Seifert E, Runte C, Riebandt M, Lamprecht - Dinnesen A, Bollmann F J Oral Rehabil 2000;27:714- 719 Spectral analysis of ‘s’ sound with changing angulation of the maxillary central incisor Runte C, Tawana D, Dirksen D, Runte B, Lamprecht-Dinnesen A, Bollmann F, Seifert E, Danesh G IJP 2002;15: 254-258
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