selection of teeth

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selection of teeth

  1. 1. Selection of artificial teeth
  2. 2. GOALS FOR THE SELECTION OF ARTIFICIAL TEETH <ul><li>Construct a denture to : </li></ul><ul><li>Function well </li></ul><ul><li>Allow pt: speak normally </li></ul><ul><li>Esthetically pleasing </li></ul><ul><li>Will not abuse the natural tissues </li></ul>
  3. 3. TOOTH SELECTION STAGES <ul><li>ANTERIOR TEETH SELECTION(ATS) </li></ul><ul><li>POSTERIOR TEETH SELECTION </li></ul>
  4. 4. ANTERIOR TEETH SELETION (ATS) <ul><li>SELETION CRITERIA: </li></ul><ul><li>Selection of tooth size </li></ul><ul><li>Selection of tooth shape (Form) </li></ul><ul><li>Selection of tooth colour ( shade) </li></ul><ul><li>Selection of tooth material </li></ul>
  5. 5. Selection of tooth size <ul><li>Size has three dimensions: </li></ul><ul><li>Mesio - distal width </li></ul><ul><li>Occluso - gingival height </li></ul><ul><li>Facio - lingual thickness </li></ul>
  6. 6. GUIDES FOR THE SELECTION OF ANTERIOR TEETH SIZE <ul><li>Pre – Extraction guides </li></ul><ul><li>Post - Extraction guides </li></ul>
  7. 7. PRE-EXTRACTION GUIDES FOR THE SELECTION OF TOOTH SIZE <ul><li>Diagnostic casts: </li></ul><ul><li>most reliable guide </li></ul><ul><li>Helps to duplicate pt: original teeth shape, size & positional arrangement . </li></ul><ul><li>Especially useful in immediate dentures. </li></ul>
  8. 8. PRE-EXTRACTION GUIDES FOR THE SELECTION OF TOOTH SIZE <ul><li>Photographs: </li></ul><ul><li>Provide information on width & form of teeth (rarely on color). </li></ul><ul><li>Usefulness depends on the extent of teeth visibility </li></ul><ul><li>Human size photographs are more valuable </li></ul><ul><li>Digitization of images make computer assisted vision possible. </li></ul>
  9. 9. PRE-EXTRACTION GUIDES FOR THE SELECTION OF TOOTH SIZE <ul><li>3 . RADIOGRAPHS: </li></ul><ul><li>helps in size & form selection </li></ul><ul><li>Need compensation for magnification </li></ul><ul><li>Distortion of radiographic image is an inherent problem. </li></ul><ul><li>4. EXTRACTED TEETH: </li></ul><ul><li>Excellent guide for tooth size & form selection. </li></ul><ul><li>Not a good guide to select shade of teeth. </li></ul><ul><li>5. Previous Dentures: </li></ul>
  10. 10. POST-EXTRACTION GUIDES FOR THE SELECTION OF TOOTH SIZE <ul><li>GUIDES TO DETERMINE THE TOOTH WIDTH </li></ul><ul><li>Size of the face: </li></ul><ul><li>Anthropometric Measurements </li></ul><ul><li>Bi-zygomatic width </li></ul><ul><li>Cranial circumference </li></ul><ul><li>Ratio of cranial circumference to the combined upper anterior six teeth width is 10:1. </li></ul>
  11. 11. GUIDES TO DETERMINE THE TOOTH WIDTH <ul><li>3 . CORNER OF THE MOUTH: </li></ul><ul><li>Line drops over the max: rim from corner of the mouth at rest, corresponds to the distal surface of the canine. </li></ul><ul><li>4. ALA OF THE NOSE: </li></ul><ul><li>A vertical line dropping from the ala of the nose usually passes along through middle of canine. </li></ul>
  12. 12. GUIDES TO DETERMINE THE TOOTH OCCLUSO-GINGIVAL HEIGHT <ul><li>HIGH LIP LINE: </li></ul><ul><li>2 . INTER-ARCH SPACE: </li></ul>
  13. 13. GUIDES TO DETERMINE THE TOOTH FACIO- LINGUAL THICKNESS <ul><li>Thicker teeth should be prefer. </li></ul><ul><li>Can be rotated & space out to give more realistic appearance. </li></ul><ul><li>Allow more depth while setting the teeth. </li></ul>
  14. 14. SELECTION OF TOOTH FORM <ul><li>Shape/form of artificial teeth is three dimensional. Therefore teeth has got three important forms, </li></ul><ul><li>FACIAL FORM </li></ul><ul><li>LATERAL /PROXIMAL FORM </li></ul><ul><li>AN INCISAL FORM </li></ul>
  15. 15. FACIAL FORM <ul><li>Leon Williams Theory: </li></ul><ul><li>Face form corresponds to facial form of inverted Central incisor. </li></ul><ul><li>Similarly, Face form corresponds to arch form. </li></ul><ul><li>Face form can be categorized into three primary forms; </li></ul><ul><li>Square form </li></ul><ul><li>Tapering form </li></ul><ul><li>Ovoid form </li></ul>
  16. 16. LATERAL /PROXIMAL FORM & AN INCISAL FORM <ul><li>Lateral face form determine the lateral form of the artificial teeth </li></ul><ul><li>Lateral face form can be categorized into; </li></ul><ul><li>Straight </li></ul><ul><li>convex </li></ul>
  17. 17. Selection of tooth colour ( shade) Colour of an object is recognized when a light of a particular wavelength is reflected off an object & then falls on the retina of the eye
  18. 18. Properties of colour <ul><li>Colour has got the three important qualities: </li></ul><ul><li>HUE: </li></ul><ul><li>Particular variety of colour(red, green,etc) </li></ul><ul><li>Determined by the wavelength of reflected light. </li></ul><ul><li>Shorter the wavelength, the closer the hue is to the violet portion. </li></ul><ul><li>longer the wavelength, the closer the hue is to the red portion. </li></ul>
  19. 19. Properties of colour <ul><li>CHROMA: </li></ul><ul><li>Amount of colour. </li></ul><ul><li>Canine is more saturated then other anterior teeth. </li></ul><ul><li>VALUE: </li></ul><ul><li>Represent amount of black or white. </li></ul><ul><li>The brightness depends on the amount of light energy reflects/transmits by an object. </li></ul><ul><li>TRANSLUCENCY: </li></ul><ul><li>Represents the amount of light transmits through an object. </li></ul><ul><li>Predominant in the area of incisal edges &/or proximal surfaces </li></ul>
  20. 20. FACTORS EFFECTS THE COLOUR OF NATURAL TEETH <ul><li>AGE: As age progresses teeth become more opaque . </li></ul><ul><li>WEAR: Teeth looks more glossy, smooth & prone to stain. </li></ul><ul><li>GENDER: Females have more whiter teeth. </li></ul><ul><li>DEMINERALIZATION: teeth gets more prone to staining. </li></ul><ul><li>STAINS: Both extrinsic & intrinsic stains effects the actual shade of the natural standing teeth . </li></ul><ul><li>POSITION OF TEETH IN DENTAL ARCH: Canine is having more saturation of a specific hue . </li></ul>
  21. 21. SHADE REPLICATION <ul><li>Process of replicating the colour of adjacent teeth in an artificial prosthesis, having following steps: </li></ul><ul><li>SHADE MATCHING PHASE: </li></ul><ul><li>a) visual shade matching’ </li></ul><ul><li>b) Instrumental colour analysis. </li></ul><ul><li>2. SHADE DUPLICATION PHASE: </li></ul>
  22. 22. FACTORS INFLUENCE THE APPERANT COLOUR OF AN OBJECT <ul><li>Physical properties of an object. </li></ul><ul><li>Nature of the light. </li></ul><ul><li>Subjective assessment of an observer. </li></ul>
  23. 23. SHADE SELECTION FOR EDENTULOUS PATIENT <ul><li>PRE_EXTRACTION GUIDES: </li></ul><ul><li>Not particularly helpful for shade selection, </li></ul><ul><li>Photographs </li></ul><ul><li>Extracted teeth </li></ul>
  24. 24. SHADE SELECTION FOR EDENTULOUS PATIENT <ul><li>POST-EXTRACTION GUIDES: </li></ul><ul><li>COLOUR OF THE EYES & HAIRS </li></ul><ul><li>Little correlation exist (Hallarman). </li></ul><ul><li>Hair colour is unreliable. </li></ul><ul><li>Black eye individuals have darker teeth shade </li></ul><ul><li>SKIN COLOUR: </li></ul><ul><li>Fair skinned individuals can be given with lighter shades. </li></ul><ul><li>Lighter shades on Darker skinned individual look more conspicuous. </li></ul>
  25. 25. POST-EXTRACTION GUIDES: <ul><li>DENTOGENIC CONCEPT: </li></ul><ul><li>Concept proposed by FRUSH & FISHER. </li></ul><ul><li>Has got the great impact on selection of teeth. </li></ul><ul><li>Teeth selected according to this concept consider the following factors in the given order. </li></ul><ul><li>GENDER: </li></ul><ul><li>FEMALES HAVE, </li></ul><ul><li>Delicate look accorded by rounding the point angles & avoiding the sharp angles in the contour of the teeth. </li></ul><ul><li>Select the small lateral incisors </li></ul><ul><li>Set the lateral incisor at higher level than centrals. </li></ul>
  26. 26. DENTOGENIC CONCEPT: <ul><li>2 . PERSONALITY: </li></ul><ul><li>Patient can have VIGOROUS or DELICATE personality </li></ul><ul><li>Vigorous look can be given by, </li></ul><ul><li>Selecting wider centrals </li></ul><ul><li>Wearing the centrals & canine </li></ul><ul><li>Selecting the darker shade </li></ul><ul><li>Sharp line & point angles </li></ul><ul><li>Delicate personality can be created by , </li></ul><ul><li>More paler teeth </li></ul><ul><li>Rounded contours. </li></ul>
  27. 27. DENTOGENIC CONCEPT: <ul><li>AGE: </li></ul><ul><li>Aged appearance can be given by, </li></ul><ul><li>Wearing the incisal edges. </li></ul><ul><li>Proximal wear can also be incorporated. </li></ul><ul><li>More of the cervical portion visible to give gingival recession appearance. </li></ul><ul><li>Select darker shade. </li></ul><ul><li>Age characterized molds are also available. </li></ul>
  28. 28. Posterior tooth selection
  29. 29. CONSIDERATIONS FOR THE SELECTION OF TEETH <ul><li>Masticatory function </li></ul><ul><li>Preservation of ridge </li></ul><ul><li>Denture stability </li></ul><ul><li>Soft tissue health </li></ul><ul><li>Esthetics </li></ul>
  30. 30. SELECTION CRITERIA FOR POSTERIOR TEETH <ul><li>Colour </li></ul><ul><li>Mesiodistal width </li></ul><ul><li>Buccolingual width </li></ul><ul><li>Occlusogingival length </li></ul><ul><li>Cuspal inclination </li></ul><ul><li>Material selection </li></ul>
  31. 31. <ul><li>SELECTION CRITERIA FOR POSTERIOR TEETH </li></ul><ul><li>COLOUR SELECTION: </li></ul><ul><li>The upper premolars & mesiobuccal half of the 1 st molar are usually visible during smile. </li></ul><ul><li>Canine are the darkest teeth </li></ul><ul><li>Premolars & molars should be slightly lighter in shade than canine. </li></ul><ul><li>The difference should not be too much obvious. </li></ul>
  32. 32. SELECTION CRITERIA FOR POSTERIOR TEETH <ul><li>2. Mesio-Distal width selection: </li></ul><ul><li>Mesio-distal width is dictated by the length of mand: residual ridge from the distal of the canine to retro-molar pad. </li></ul><ul><li>Arrangement of three post: teeth is more often the norm & will reduce the potential for the placement of the 2 nd molar too far posteriorly. </li></ul><ul><li>Max: post: teeth that extends too close to the post: border of max: denture may cause cheek biting. </li></ul>
  33. 33. SELECTION CRITERIA FOR POSTERIOR TEETH <ul><li>3. BUCCO-LINGUAL WIDTH SELECTION: </li></ul><ul><li>Should be less than the width of natural teeth. </li></ul><ul><li>Narrow occlusal table reduces the level of forces needed to masticate. </li></ul><ul><li>Narrow occlusal table allows the development of correct form of polished surfaces by allowing the buccal & lingual denture flanges to slope away from occlusal surface. </li></ul><ul><li>Correct polished surface form assist cheeks & tongue in maintaining the denture in position. </li></ul>
  34. 34. <ul><li>SELECTION CRITERIA FOR POSTERIOR TEETH </li></ul><ul><li>4. OCCLUSO- GINGIVAL LENGTH SELECTION: </li></ul><ul><li>Vertical height should correspond to the available Interarch space. </li></ul><ul><li>Max: 1 st Premolar length should be compatible with the max: canine. </li></ul><ul><li>Longer teeth can be selected for a pt: where there is more interarch space &/or older pt: to mimic gingival recession. </li></ul>
  35. 35. SELECTION CRITERIA FOR POSTERIOR TEETH <ul><li>5. CUSPAL MORPHOLOGY SELECTION: </li></ul><ul><li>Based on cuspal morphology posterior teeth can be classified into: </li></ul><ul><li>Non-anatomical teeth </li></ul><ul><li>Anatomical teeth </li></ul><ul><li>Combination of anatomic & non-anatomic teeth </li></ul>
  36. 36. CUSPAL MORPHOLOGY SELECTION: <ul><li>NON–ANATOMICAL TEETH </li></ul><ul><li>Also known as Flat or Monoplane or Cuspless or Zero degree teeth. </li></ul><ul><li>Historically, </li></ul><ul><li>HALL ( 1929) was the 1 st person to design cuspless teeth called “INVERTED CUSP TEETH.” </li></ul><ul><li>“ TRUE-KUSP” design by Myerson in 1929. </li></ul><ul><li>“ CHOPING BLOCK” by Nelson in 1934. </li></ul><ul><li>“ NON-LOCK by Swenson in 1939. </li></ul><ul><li>“ VITALLIUM OCCLUSAL” by Hardy in 1946. </li></ul><ul><li>Introduced in order to reduce lateral forces acting on the denture. </li></ul><ul><li>Balanced occlusion Can be obtained by introducing “Balancing ramps”. </li></ul><ul><li>. </li></ul>
  37. 37. NON–ANATOMICAL TEETH <ul><li>INDICATIONS: </li></ul><ul><li>Flat ridge cases </li></ul><ul><li>Abnormal jaw relation case </li></ul><ul><li>Where difficulty is faced in recording the centric relation. </li></ul><ul><li>Where balanced occlusion is not planed. </li></ul>
  38. 38. NON–ANATOMICAL TEETH <ul><li>ADVANTAGES: </li></ul><ul><li>Freedom of occlusal movements from centric to eccentric jaw positions. </li></ul><ul><li>Elimination of lateral forces that can destabilized the denture. </li></ul><ul><li>When denture settling take place due to denture abuse no cuspal interference occur. </li></ul><ul><li>DISADVANTAGES: </li></ul><ul><li>Not esthetically pleasing. </li></ul><ul><li>Difficult to balance </li></ul><ul><li>Reduced masticatory efficiency </li></ul>
  39. 39. ANATOMICAL TEETH <ul><li>Can be classified on the bases of cuspal inclines. </li></ul><ul><li>Cuspal inclines vary from 20 degree to 45 degree. </li></ul><ul><li>INDICATIONS: </li></ul><ul><li>Good ridge form with sufficient retention & support. </li></ul><ul><li>Where balanced occlusion is planed. </li></ul><ul><li>Where possible to record & transfer the centric relation with accuracy. </li></ul>
  40. 40. ANATOMICAL TEETH <ul><li>ADVANTAGES: </li></ul><ul><li>Easier to balance </li></ul><ul><li>Better masticatory efficiency </li></ul><ul><li>Reduced chewing cycles </li></ul><ul><li>Better esthetics </li></ul>
  41. 41. COMBINATION OF ANATOMIC & NON-ANATOMIC TEETH <ul><li>This concept was proposed by payne in 1941, called </li></ul><ul><li>“ LINGUALIZED OCCLUSION.” </li></ul><ul><li>Lingualized scheme use upper anatomical & lower either semi or nonanatomical teeth molds. </li></ul><ul><li>The max: lingual cusp set into the lower central fossa ( MOTAR & PESTLE) </li></ul><ul><li>The mand: buccal cusp kept out of the max: central fossa. </li></ul><ul><li>Occlusion can be balanced by introducing the “compensating curves”. </li></ul>
  42. 42. EXAMPLES OF LINGUALIZED INTEGRATION MOLDS <ul><li>Mayerson Lingualized Integration( MLI). </li></ul><ul><li>Gysi’s cross bite posterior.( 1927) </li></ul><ul><li>French’s Modified posteriors.(1935) </li></ul><ul><li>Max Pleasure Scheme.(1937) </li></ul><ul><li>Vita Linguoform. </li></ul>
  43. 43. LINGUALIZED OCCLUSION <ul><li>ADVANTAGES: </li></ul><ul><li>This concept provides maximum intercuspation. </li></ul><ul><li>Absence of deflective contacts. </li></ul><ul><li>Adequate cuspal height for selective grinding. </li></ul><ul><li>Natural & pleasing appearance. </li></ul><ul><li>Can be used in pt: where recording the CR is uncertain. </li></ul><ul><li>Occlusion can be balanced . </li></ul>
  44. 44. 1. Acrylic resin teeth <ul><li>INDICATIONS: </li></ul><ul><li>When there is opposing natural dentition. </li></ul><ul><li>When opposing dentition has got the gold crowns or inlays. </li></ul><ul><li>Where there is reduced interarch space. </li></ul><ul><li>Where occlusal adjustment is required. </li></ul>
  45. 45. MATERIAL SELECTION FOR ARTIFICIAL TEETH <ul><li>1. Acrylic resin teeth </li></ul><ul><li>2. Porcelain teeth </li></ul>
  46. 46. <ul><li>1. Acrylic resin teeth </li></ul><ul><li>INDICATIONS: </li></ul><ul><li>When there is opposing natural dentition. </li></ul><ul><li>When opposing dentition has got the gold crowns or inlays. </li></ul><ul><li>Where there is reduced interarch space. </li></ul><ul><li>Where occlusal adjustment is required. </li></ul>
  47. 47. Acrylic resin teeth <ul><li>ADVANTAGES: </li></ul><ul><li>Inexpensive </li></ul><ul><li>Easy to grind & adjust </li></ul><ul><li>Absorb the occlusal stresses </li></ul><ul><li>Does not wear the opposing natural teeth. </li></ul><ul><li>Bond chemically to denture base. </li></ul><ul><li>Self adjusting & polishing. </li></ul><ul><li>Softer impact sound </li></ul><ul><li>DISADVANTAGES: </li></ul><ul><li>Wear easily </li></ul><ul><li>Loss of VD because of wear. </li></ul><ul><li>Stains with time. </li></ul><ul><li>Shearing efficiency with time. </li></ul>

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