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selection of teeth

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