Introduction in Prosthodontics (dental prosthetics)

1. Introduction in Prosthodontics(dental prosthetics) Dr. Waseem Bahjat Mushtaha Specialized in prosthodontics

2. Introduction: Prosthesis: an artificial appliance which replace lost or congenitally missing tissue. Some prosthesis restore both function and appearance of tissue they replace other merely restore one of these factors.

3. Prosthetics: is the art and science of designing and fitting artificial substitutly to replace lost or missing tissue. Prosthodontics (dental prosthetics): Is the branch of dental art and science which with the replacement of missing teeth and oral tissue to restore and maintain oral form, function, appearance, phonetics and health.

5. Complete denture prosthodontics: involves an artificial replacement of the lost natural dentition and associated structures of the maxilla and mandible for patient who has lost all their remaining natural teeth.

7. Function of complete denture: 1- Mastication: chew food for swallowing and digestion. 2- Speech (phonetics): the teeth either natural or artificial assist the tongue and lips to form some of the sounds of speech. 3- Appearance (aesthetic): is influence by the shape of jaws together with the position and occlusal relation ship of the teeth. 4- Health of the alveolar bone and the tempro- mandibular joints (T.M.J).

8. Complete dentures have three structures: 1- The fitting surface. 2- The occlusal surface. 3- The polished surface.

9. Anatomy and physiology in relation to complete denture I- oral mucosa membrane (tissue compression) 1- The bone of the upper and lower edentulous jaws are covered with a soft tissues and the oral cavity is lined with soft tissue known as mucosa membrane. 2- This mucosa membrane is composed of two layer mucosa and sub mucosa. 3- Mucosa consists of stratified squamous epithelium.

10. 4- The thickness and consistency of the sub mucosa are largely responsible for the support denture. 5- In the edentulous patient the crest of residual alveolar ridge + hard palate has masticatory mucosa have firmly attached to the supporting bone. 6- The sub mucosa in the region in the median palatine suture of the maxillary bone is extremely thin so will become inflamed when wearing denture.

11. II- the alveolar ridges 1) The residual ridge consists of: 1- Denture – bearing mucosa. 2- Sub mucosa 3- Periostem 4- Under laying residual alveolar bone.

12. Types of alveolar ridges and palate formation: I- upper ridges 1- well – developed (upper ridge) but not abnormally thick ridges and palate with a moderate vault. 2- Flat –v- shaped palate usually associated with bulky ridge. 3- Flat palate with small ridge and shallow. 4- Ridge exhibiting gross under cut area.

14. II- lower ridge 1- Broad and well developed lower ridges. 2- Ridges exhibiting under cut areas. 3- Well developed but narrow or knife edged ridges. 4- Flat ridge.

16. Anatomical land marks of complete dentures I- INTRA ORAL ANATOMICAL LAND MARK II- EXTRA ORAL LANDMARK

17. Upper denture

18. I- INTRA ORAL ANATOMICAL LAND MARK 1- Stress bearing (supporting area). 2- Peripheral or limiting (sealing) areas

19. Incisive papilla

20. I- supporting structure 1- Incisive papilla: 1) It is the elevation of the tissue that covers the incisive foramens (the opening of the nasopalatine canal which, carry the nasopalatine vessels and nerves). 2) Location, on the median line behind and between the central incisors. 3) In old edentulous mouth it is located on the center of the ridge due to resorption. 4) It may require relief in the finished denture base to prevent irritation of the nasopalatine nerve.

21. 2- Rugae area

22. 2- Rugae area: 1) The rugae are irregular shaped rolls of soft tissue. 2) Location, lie in the anterior part of the hard palate. 3) It is considered a secondary stress- bearing area for the upper complete denture. 4) With the natural dentitions, it assists in formation of sounds like the letter s.

23. Residual alveolar ridge

24. 3- Residual alveolar ridge 1) The residual alveolar ridge and most of the hard palate are considered the major or primary stress bearing area in the upper jaw. 2) The crest of the residual ridge is covered with layer of fibrous connective tissue which is most favorable for supporting the denture because of it is firmness and position. 3) The crest of ridge is described as a primary stress-bearing area and most tolerated to resisting the denture movement and resulting irritation

25. Median palatine raphe

26. 4- Median palatine raphe: 1) It is median suture formed by the union of the palatine processes of maxilla and horizontal plates of the palatine bones. 2) It is covered with mucosa membrane and little sub mucosa tissue. 3) This area may require selective relief with in denture base.

27. 5- The tuberosities

28. 5- The tuberosities 1) The posterior part of the maxillary alveolar ridge forms prominence called the tuberosity. 2) It is usually a bulbous extension of the residual ridge in the second and third molar region. 3) Terminating hamular notch.

29. 4) Large tuberosities bounded by deep salci offer very satisfactory denture 5) Tuberosities exhibiting gross undercuts may require surgical treatment. 6) They are identified in the finished denture by the tubercular fossa.

30. 6- Fovea palatinae

31. 6- Fovea palatinae: 1) These are indentations near the midline of the palate formed. 2) They are close to the vibrating line and always in soft tissue. 3) Which makes an ideal guide for the ending of the posterior border of the denture

32. 7- Tours palatinus

33. 7- Tours palatinus: 1) At the junction of the palatine process of the maxillary bone, in the midline or on each side lateral to the midline. 2) A bony projection is some times observed. 3) It varies in size and form. 4) If it is too large it should be surgically removed. 5) If it is small the denture base should be relieved of that area.

34. Border structures that limit the periphery of the upper denture (limiting structure) 1- The maxillary labial frenum: 1) It is a fibrous bond covered by mucosa membrane that extends from the labial aspect of the residual alveolar ridge to the lip. 2) It has no muscle fiber and has no action of it is own. 3) The labial in the labial flange of the denture must be just wide and deep enough to allow the frenum to pass through it without manipulation of the lip.

35. The maxillary labial frenum

36. 2- Labial vestibule and labial flange: 1) The labial flange of maxillary denture occupies a potential space bounded by: labial aspect of the residual alveolar ridge, the muco-labial alveolar fold, and the orbicularis oris muscle. 2) The length of this flange should not extend beyond the normal drape of the muco-labial fold. 3) The thickness of the flange depends up on the degree of alveolar resorption. 4) The denture border area between the labial frenum and the buccal frenum is known as the maxillary labial flange.

37. 2- Labial vestibule and labial flange

38. 3- Buccal frenum: 1) It is a some times a single fold of mucosa membrane, sometimes double and in some mouths, broad and fan shaped. 2) The buccal notch in the denture must be broad enough to allow the movement of the buccal frenum. 3) Inadequate provision for the buccal frenum or excess thickness of the flange distal to the buccal notch can cause dislodgment of the denture when the cheeks are moved posterioly as in abroad smile.

39. Buccal frenum

40. 4- Buccal vestibule: 1) It is extended from the buccal frenum to the hamular notch. 2) It houses the buccal flange of the denture. 3) This space between the ridge and cheek. 4) The buccal flange of maxillary denture should fill but not over fill it. 5) The thickness of the distal end of the buccal flange of the denture must be adjusted to accommodate the ramus and cronoid process and masseter muscle as they function. The distal end of the buccal flange must not be too thick because the ramus will push the denture out of the place during opening or lateral movement of mandible.

41. Buccal vestibule

42. 5- Pterygomaxillary (hamular) notch 1) It is formed by the pterygoid process of sphenoid bone and the posterior end of maxilla, back to the tuberosity. 2) It is used as boundary of the posterior border of maxillary denture. 3) It is important for sealing.

43. Pterygomaxillary (hamular) notch

44. 6- Vibrating line of the palate 1) It is an imaginary line drawn across the posterior part of the palate that marks the beginning of motion in the soft palate when the patients say "ah". 2) It extends from one pterygomaxillary notch to other. 3) It is not the junction between hard and soft palate. It is always in soft palate.

45. Vibrating line of the palate

46. 7- Posterior palatal border (Potsdam) 1) The distal edge of the maxillary denture base terminates in the posterior palatal seal area. 2) This denture edge generally ends at or before the vibrating line. 3) The seal of this border must be situated in the region of compressible tissue just distal to the hard palate. (But it must be anterior to the vibrating line).

47. Posterior palatal border (Potsdam)

48. 8- The soft palate Patient may be broadly divided in to classes with regard to non mobile area: 1) Those whose palates exhibit movement at the junction of the hard palate and soft palate. 2) Those whose soft palates move some distance behind the junction.

49. The width of the area available for the posterior palatal seal will depend up on the curvature of the soft palate. There are three classes of curvature of soft palate: Glass I: the soft palate has a gentle curvature and allows for abroad posterior palatal seal area. Glass II: the soft palate has a medium curvature and allow for a medium width of the posterior palatal seal area. Glass III: the soft palate has a sharp and abrupt curvature and allows for a narrow posterior palatal seal area.

50. The soft palate