Anatomic and Physiologic Considerations of Tongue in Prosthodontics.pptx

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1. Anatomic and Physiologic Considerations of Tongue in Prosthodontics REDDY. PRIYA DARSHINI 1 st year MDS DEPT OF PROSTHODONTICS

2. Contents Introduction Anatomy Development of tongue Muscles of tongue Nerve supply Arterial supply Anomalies of tongue Functions of tongue Examination of tongue Prosthetic management of tongue Conclusion References

3. Introduction The word ‘Tongue’ is derived from the Latin word ‘lingua’ and Greek word ‘ Glossa ’. Tongue is a highly mobile muscular organ present in the oral cavity. It is partly oral (anterior 2/3 rd) partly pharyngeal ( posterior 1/3 rd ). This well developed sensory capability is considered a protective feature as it permits the tongue to review substances before they pass in to the GI tract The tongue is in intimate contact with the lower denture & also plays an important role in the retention of the mandibular denture

4. ANATOMY Tongue is a muscular organ. Consists of oral part (ant 2/3rds) & pharyngeal part (post 1/3rds) separated by ‘ v’shaped terminal sulcus . At the ‘v’ shaped sulcus is a small depression called foramen cecum . Tongue has 1. a root 2 . a tip 3 . the body which is divided in to upper surface or dorsum and inferior surface

5. Oral (Papillary) part of the tongue It is placed in the floor & cavity of the mouth Margins are free and contact the teeth &gums Superior surface is covered with papilla Inferior surface has prominent deep lingual veins & plica fimbriata

6. Ventral surface consists of median fold called as frenulum , arising from floor of the mouth Ventral surface is smooth, and purplish with no papilla. Lingual veins are often visible as bluish streaks.

7. Pharyngeal part has plenty of lymphoid follicles, lingual tonsil & mucous glands Reflections of mucous membrane between tongue & epiglottis forms a median glossoepiglottic fold & two lateral glossoepiglottic fold

8. Development Anterior two third – from two lingual swellings - one tuberculam impar - from the first branchial arch Posterior one third – hypobranchial eminence - from the third arch Posterior most – from the fourth arch

9. 3 rd arch rapidly over grows that of second arch,which is excluded from further involvement in development of tongue

10. Superior Surface/Dorsum of Tongue

11. Papillae of the tongue Papillae are projections of mucous membrane on the dorsum of the tongue Circumvalate papillae Fungiform papillae Filliform papillae Foliate papillae

12. Filiform Papillae Cover the entire anterior part of the tongue by the keratinized epithelium. They form a tough abrasive surface involved in compressing and breaking food when the tongue is opposed to the hard palate.

13. Fungiform Papillae. Present in the anterior part of the tongue. Scattered among the numerious filliform papillae along the margins of the tongue which are round and larger than filiform papillae. Taste buds are present in the epithelium on the superior surface.

14. Foliate Papillae Consists of 4-11 ridges which alternates with grooves Present as linear folds of mucosa on the lateral margins of the posterior part of the tongue. Few taste buds are present in the epithelium of the lateral walls of the ridges.

15. Circumvallate Papillae Adjacent and anterior to the sulcus terminalis 8 to 12 in number Surrounded by a deep circular group into which open the ducts of von ebner glands, the minor salivary glands. Epithelium covering the lateral walls is non keratinised and contains taste buds.

16. Lingual Tonsils Situated near the mid line on the dorsum of the tongue just behind the vallate papillae. Is a lymphoid tissue similar to the paletine tonsil. Infection in this part of tongue will involve the tonsils. Therefore it is an important indicator of tonsillar infections.

17. Taste buds Taste buds are located on the dorsum of the tongue and are associated with the papillae Taste buds appear around 8 th week of IUL Taste buds arise by inductive interaction b/w the epithelial cells and the invading gustatory nerve cells

18. Inferior / Ventral surface of tongue Lacks papillae Linear mucosal folds present. Single median fold ( Frenulum of tongue) separates the right and left sides of tongue & continues with floor of mouth. On each side of frenulum is a Lingual Vein & lateral to vein is a rough Fimbriated fold .

19. Muscles of Tongue Muscles of tongue are paired. Arise from occipital somites , which have migrated forward carrying with them their nerve supply the 12 th cranial nerve. Consists of Intrinsic muscles - Superior longitudinal Inferior longitudinal Vertical Transverse Extrinsic muscles - Genioglossus Hyoglossus Styloglossus Palatoglossus

20. Intrinsic Muscles Occupies upper part of tongue and attached to sub-mucous fibrous layer and median fibrous septum. 1)Superior longitudinal 3)Transverse 2)Inferior longitudinal 4)Vertical These muscles alter shape of tongue by – Lenghtening & shortening Curling & uncurling apex & edges. Flattening & rounding its surface

21. Superior Longitudinal muscle. Lies beneath the mucous membrane. It shortens the tongue & makes its dorsum concave superior longitudinal muscle

22. Inferior Longitudinal Muscle . Lies between the genioglossus & hyoglossus . It shortens the tongue & makes it dorsum convex inferior longitudinal muscle

23. Found at the borders of the fore- part of the tongue Makes the tongue broad & flattened vertical muscles Vertical Muscles

24. Transverse Muscles Extends from median fibrous septum to lateral margin Makes tongue narrow & elongated transverse muscles

25. Extrinsic Muscles

26. Genioglossus It is fan shaped & forms the bulk of the tongue It arises from upper genial tubercles of the mandible & fibers fan out back

27. Upper fibers are inserted in to the tip , middle fibers in to the dorsum &lower fibers in to the hyoid bone Upper fibers retract the tip , middle fibers depress the dorsum & lower fibers protrude the tongue

28. Hyoglossus It is a thin quadrilateral muscle It arises from the whole length of the greater cornu of hyoid & front of the lateral part of the body of hyoid

29. Fibers run upward & forwards & are inserted in to the side of the tongue between styloglossus & inferior longitudinal muscle It depresses the tongue, makes the dorsum convex & helps in retracting the protruded tongue

30. Styloglossus It arises from tip & adjacent part of the anterior surface of the styloid process as well as from the upper end of the stylohyoid ligament It passes downwards & forwards & is inserted into the side of the tongue intermingling with the fibres of the hyoglossus It pulls the tongue upwards & backwards.

31. Palatoglossus It arises from oral surface of palatine aponeurosis . It descends in the palatoglossal arch ,to the side of the tongue at the junction of its oral & pharyngeal parts. Pulls up the root of the tongue approximates the palatoglossal arches & thus closes the oropharyngeal isthmus.

32. Nerve Supply

33. Nerve supply of the tongue Development of tongue from the branchial arch explains its nerve supply . Sensory supply Ant 2/3 rd - Lingual nerve for general sensation. Chorda tympani for the special sensation Post 1/3 rd - Glossopharyngeal nerve Posterior most part - vagus nerve Motor supply All the intrinsic and extrinsic muscles except the palatoglossus are supplied by the hypoglossal nerve. Palatoglossus –cranial part of accessory nerve through pharyngeal plexus

34. Arterial supply: It is chiefly derived from the lingual artery a branch of external carotid artery. The root of the tongue is also supplied by tonsillar and ascending pharyngeal artery.

35. Venous drainage: The deep lingual vein is the principal vein of the tongue. Lymphatic drainage: The tip of the tongue drains into submental nodes. The remaining part of the anterior 2/3 rd drains into the submandibular nodes. The posterior 1/3 rd of the tongue drains into jugulo-omohyoid nodes

36. ANOMILIES OF THE TONGUE Aglossia Microglossia Macroglossia Bifid tongue Ankyloglossia Lingual thyroid Fissured tongue Median rhomboid glossitis

37. Ankyloglossia Tongue type is defined on the basis of in ability to extend the tip of the tongue beyond the vermillion border of the lip. Syndromes orofacial digital syndrome trisomy 13 vanderwoode’s glasoopalatine ankylosis

38. Clinical importance Severe degree of ankylosis of an exhibit midline mandibular diastema and lingual mandibular periodontal defects. Difficulty in making the impression which hampers the retention of denture . Poor registration of lingual seal. There will be Altered speech Correction Mild – speech therapy Severe – clipping of frenum or frenectomy indicated.

39. Clinically manifested by numerous small furrows or groves often radiating from a central groove along the midline on the dorsal surface. Develop simultaneously as a sequel to geographic tongue. Fissured tongue

40. Rounded or roughly lozenge shaped, raised area that occurs in the midline of the tongue dorsum. Anterior to the vallate papilla, affected area is devoid of filliform papillae. Median rhomboid glossitis

41. Functions of Tongue Speech Mastication Deglutition Maintenance of Oral hygiene

42. Role in Speech Tongue has critical impact on speech production and needs optimal mobility to lift protrude ,flatten and contact adjacent tissues freely. Different sounds produced are Linguoalveolar Linguodental Labiodental Bilabial

43. Alveolar sounds are made with the valve formed by the contact of the tip of the tongue with the most anterior part of the palateor lingual side of anterior teeth. e.g. t,d,s,v,l . Sibilants (sharp sounds) s,z,sh,ch &j (with ch and j being affricatives) are alveolar sounds bcos the tongue and alveolus form the controlling valve. Linguoalveolar Sounds

44. Sh’ sound Sh ’ sound

45. 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. 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.

46. Dental sounds are made with the tip of the tongue extending between the upper & lower anterior teeth eg : th in this This will provide for labio lingual positioning of the anterior teeth. If about 3 mm of tip is not visible, the anterior teeth are probably too forward in placement or if the vertical overlap is excess that does not allow sufficient space for the tongue to protrude between the anterior teeth. More than 6mm of tongue extends out between teeth when such sounds are made, the teeth are probably too lingual. Linguodental Sounds

47. The sounds b ,p and m are made by contact of the lips. In b and p, air pressure is built up behind the lips and released with or without a voice sound. Insufficient support of the lips by teeth or denture base can cause sounds to be defective.therfore , anterioposterior position of anteriorteeth and thickness of labial flange can affect production of these sounds. Incorrect vertical dimension of occlusion or teeth position hindering the lip closure might influence these sounds Bilabial Sounds

48. The labiodental sounds f and v are made between the upper incisors and the posterior third of the lip. Labiodental sounds are made with the relationship of the incisal edges and lower lip. Labiodental Sounds 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.

49. 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.

50. In setting the upper anterior teeth, consideration of their labiodental position is necessary for the correct formation of the labiodentals F and V. 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.

51. Role in Mastication Tongue takes food from the floor of the mouth & the labial & buccal vestibule & places it on the occlusal surface of the teeth

52. Role in Deglutition Tongue plays an important role in deglutition during the oral phase by passing the bolus of food in to pharynx. Bolus formed during mastication is placed over dorsal surface of tongue, in this stage tongue is retracted and depressed. Posterior part of tongue is elevated and retracted against the palate. Bolus is moved in to pharynx to some extent due to the + ve pressure in the posterior part of oral cavity created by forceful contraction of tongue against palate.

53. In Oral Hygiene After the food passes in to the pharynx, the tongue scavenges the sulci with its tip to clear the mouth of fragments of food which have escaped the formation of bolus.

54. EXAMINING THE TONGUE Size Position Surface Tongue movements

55. MACROGLOSSIA- It is a condition where the tongue is enlarged. If a patient has been without teeth for long time or worn a maxillary denture against the lower anterior teeth only, the tongue becomes enlarged and powerful. Results in problem during impression making, contributing to denture instability. Tongue bitting may also occur. Tongue Size

56. Causes of MACROGLOSSIA - Down’s syndrome Congenital lymphangioma Congenital hypothyroidism Neurofibromatosis type 1 Pompe’s disease Hurler syndrome

57. TONGUE CHANGES IN EDENTULOUS PATIENT 1 . Due to long term edentulousness , the tongue expands Introduction of a new denture will be met with a dislodging competition from the tongue 2 . Edentulous patient who has not been wearing mandibular denture will often use tongue as the antagonist for the maxillary arch . Tongue becomes enlarged and powerful 3. Repeated guiding and tongue exercise will help in altering the size to some extent, over a period of time tongue will adapt to the new environment. 4. Surgical trimming has been used to reduce the bulk of tissue present in severe cases.

58. MICROGLOSSIA- It is a rare congenital anomaly manifested by the presence of small or rudimentary tongue. Facilitates impression making, but jeopardizes the lingual seal.

59. Tongue Position Tongue position is important to the prognosis of the mandibular denture. CLASSIFICATION OF TONGUE POSITION : Class I Tongue lies in the floor of the mouth with the tip forward and slightly below the incisal edges of the mandibular anterior teeth . Class II Tongue is flattened and broadened but the tip is in the normal position. Class III Tongue is retracted and depressed in to the floor of the mouth with the tip curled upward , downward or assimilated in to the body of the tongue.

60. Class I – most favourable prognosis. - floor of tongue will be high enough to cover the lingual flange of denture producing border seal. Class II &III – unfavourable positions as they drop the level of floor of mouth and do not provide an adeqate lingual seal.

61. SURFACE Variation in colour , texture,or shape indicates an unhealthy condition of an indivudual . Common disorders Black hairy tongue Benign migratory glossitis Tongue tie Glossodynia Fissure tongue

62. Retromylohyoid fossa Is the area posterior to the mylohyoid muscle It is bounded by the retromylohyoid curtain Protrusion of the tongue causes it to move forward The denture border should extend posteriorly to contact the retromylohyoid curtain when the tip of the tongue is placed against front part of upper ridge

63. Alveololingual sulcus Is the space between the residual ridge & the tongue from the lingual frenum to the retro mylohyoid curtain 1) ANTERIOR REGION- It extends from the lingual frenum to where the mylohyoid ridge curves down below the level of the sulcus – premylohyoid fossa Impression should extend down to contact the mucous membrane of the floor of the mouth when the tip of the tongue touches the upper incisors

64. 2) Middle region It extends from pre mylohyoid fossa to the distal end of mylohyoid ridge curving medially from the mandible When the middle of the lingual flange is made to slope towards the the tongue ,it can extend below the level of the ridge The tongue rests on top of the flange & aids in stabilizing the denture on the residual ridge

65. 3) Posterior region It extends from distal end of mylohyoid ridge to retromylohyoid curtain The denture should extend to contact retromylohyoid curtain when tip of tongue is placed on upper part of residual ridge

66. PROSTHETIC MANAGEMENT IN TONGUE Impression making (border moulding ) Jaw relation Teeth arrangement. Denture insertion.

67. Border Molding of Lingual Areas Distolingual & post mylohyoid areas should be developed bilaterally. Have the patient place the tongue in the distal part of the palate in the right & left buccal vestibule Sublingual flange is developed in its entirety Have the patient place the tongue in the anterior part of the palate & then gently wipe their upper lip with the tip of the tongue. Protruding the tongue determines length of the lingual flange of the tray. Pushing the tongue against anterior part of palate causes base of tongue to spread out and develop thickness of anterior part of flange.

68. In Jaw Relations Tongue plays a major role in orientation of occlusal plane The occlusal plane should be at the level of dorsum of the tongue. In recording centric relation instruct the patient to turn the tongue backward toward the posterior border of the upper denture

69. Teeth must never be set inside the alveolar ridge or they will cramp the tongue causing movement of dentures and irritation to the patient. 2) The lower denture should present lingual flanges to the tongue which slope slightly inwards from above downwards. That is no concavities should be presented to the tongue into which its lateral borders can expand and so lift the denture. In Arrangement Of Teeth

70. 3) Occlusal plane of lower denture should be kept low, thus allowing the lateral borders of tongue to rest upon the occlusal surfaces of teeth when mouth is opened to receive food and so prevent the lower denture from rising. 4) When the mandibular teeth extend too high ,the tongue cannot reach the labial or buccal vestibule to retrieve food. When the mandibular teeth are too low,the tongue will not be supported at the lateral margins & will enlarge in a lateral direction.

71. 5) Teeth should be arranged in the Neutral zone so that the teeth will occupy a space determined by the functional balance of tongue & orofacial musculature. 6) If the teeth are too far lingual ‘t’ will sound more like a ’d’ ,if they are too far anterior the ‘d’ will sound more like a ’t’ If the anterior teeth are too far back ,the tongue will be forced to arch itself up to higher position & airway would too small

72. After Denture Insertion Initial discomfort associated with wearing new denture – Sore tongue - It is related to the habit of thrusting the tongue against the denture Most common complaint – Loose mandibular denture Mandibular denture depends on proper tongue position to maintain adequate peripheral seal & stability . Successful denture wearer - one who has learned the importance of tongue position.

73. Burning mouth- movements of denture bases may tend to exacerbate the symptoms of burning and so the occlusion should be balanced in all positions. sometimes its restricted only to ant 1/3 rd of tongue, this may be due to restricted tongue space in denture, either due to upper anteriors set back on the ridge and so tongue continually taps them, or lower posteriors set far lingually that they irritate the sides of tongue.

74. Action of tongue in denture wearers for control of dentures– The dorsum of tongue is pressed against the back of upper denture to prevent it dropping when incising. The tip is pressed forwards and downwards against the anterior lingual surface of lower denture when lip tends to force the denture backwards. The lateral borders of tongue rest on occlusal surface of lower denture when opening of mouth.

75. In normal position, the tongue appears absolutely relaxed This is the most favourable position for maintaning the lingual border seal which will enhance the retention of the denture

76. A small Training groove of about 10mm long , 2mm wide ,and 2mm deep is made just below the anterior central incisor, using miltex MX-3 resin bur or a similar bur The patient is instructed to place the tongue on the Groove, at all times except when eating and speaking Most of the patients can learn to keep the tongue in this position in few weeks

77. Polished Surface of Denture The polished surface of a denture consists of the labial, buccal , lingual, and palatal of a denture base and the outer surface of artificial teeth except the occlusal surface. If the polished surface is appropriately contoured and if it is in harmony with the movement of the surrounding tissues such as the cheeks lips and the tongue then it aids in the retention of the denture.

78. In Fixed Partial Dentures Tongue can be an interference during preparation & impression procedures. Care should be taken not to injure the tongue. Tongue can be retracted by means of mouth mirror , Svedopter –metal saliva ejector with tongue deflector.

79. Conclusion Tongue is a important organ which plays a major role in mastication , phonetics, deglutition. Tongue helps in denture construction and plays a major role in stabilizing and retention of denture.

80. References Richard L Drake, Wayne Vogi , Adam W M Mitchell: Gray’s Anatomy for Students, 2 nd edition. Canada, Chirchill Livingstone, 2010. Chaurasia BD : Human Anatomy – Regional and applied dissection and clinical, Volume 3 Head, Neck and Brain, 4 th edition. New Delhi, CBS Publishers, 2006. Berkovitz BKB, Holland GR, Moxham BJ: Oral Anatomy, Histology and Embryology, 3 rd Edition. London, Mosby Publishers, 2005. Sheldon Winkler: Essentials of Complete Denture Prosthodontics , 2 nd edition. India , AITBS Publishers, 2009. Roy Macgregor : Clinical Dental Prosthetics , 3 rd Edition. Bombay, Varghese Publishing House, 1994. Antonio Nanci : Tencates Oral Histology Development, Structure and Function., 6 th Edition. NewDelhi , 2005.

81. Charles M Heartwell , Jr , Arthur O Rahn : Syllabus of Complete Dentures, 4 th Edition. Bombay , Varghese Publishing House, 1992. Zarb , Bolender , Carlsson : Prosthodontic Treatment for Edentulous Patients-Complete dentures and implant supported prostheses, 12 th Edition. India, Elsevier, 2005. Sharry John J, Good B : Complete Denture Prosthodontics , 3 rd Edition. Mc Graw Hill, 1974. Influence of tongue activity on lower complete denture retention under biting forces . Acta of Bioengineering and Biomechanics. Vol. 10, No. 3, 2008.