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Occlusion in complete denture

Occlusion in complete denture. all the occlusal concepts clearly explained with schematic diagrams and illustrations by dr anil goud director of asian dental academy.

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Occlusion in complete denture

  1. 1. Occlusal Considerations in Complete Dentures Dr. M Anil Goud. Professor Dept of Prosthodontics NRDRN Dental College Nanded
  2. 2. Introduction  A literal definition of the term occlusion is the act of closure or being closed  But this term should have in it’s definition the concept of a multifactorial, functional relationship between the teeth and the other components of the masticatory system as well as other areas of head and neck that directly or indirectly relate to function, Para function or dysfunction of the masticatory system
  3. 3. Definitions  Dorland’s dictionary(1985)-relation of maxillary and mandibular teeth when in functional contact during activity of mandible  GPT 8 – 1) The act or process of closure or of being closed or shut off 2) The static relationship between incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogue
  4. 4. Difference between natural and artificial teeth  Proprioceptive feedback of periodontal tissues  Pressure of occlusion on Individual tooth unit  Malocclusion of occlusion uneventful for years  Incising  Bilateral balance  Forces of mastication 5 to 175 pounds in natural teeth 9 pound in incisor area,22-24 pound in premolar & molar area in complete denture
  5. 5. Requirements of complete denture occlusion Stability Balanced occlusion Functional lever balance by tooth to ridge position Cutting penetrating and shearing efficiency of occlusal surfaces Anterior incisal clearance during posterior masticatory functions Minimum area of occlusal contacts to reduce the forces
  6. 6. Requirements of incising units Sharp No contact during mastication Less incisal guidance considering esthetics and phonetics Contact only during protrusive incising function
  7. 7. Requirements of the working occlusal units Efficient in cutting and grinding Should have decreased Buccolingual width Should function as group with simultaneous harmonious contacts Should over the ridge crest for lever balance Should have plane of occlusion as parallel as possible to mean foundation area
  8. 8. Requirements of balancing occlusal units Should contact on the second molars when the incising units contact in function Should contact at the end of chewing cycle when the working units contact Should have smooth gliding contacts for lateral and protrusive excursions
  9. 9. Axioms for artificial occlusion Sears  Smaller area of occlusal surfaces, smaller the forces transmitted  Vertical forces on inclined surface causes non vertical force  Vertical forces on inclined supporting tissue causes non vertical force  Vertical force outside & lateral to the ridge creates tipping forces on the bases
  10. 10. Occlusal schemes for complete denture Anatomically shaped teeth in upper and lower dentures Non-anatomically shaped teeth in both dentures A combination of both types, usually anatomically shaped teeth in the upper
  11. 11. Anatomic teeth Advantages Efficient in cutting of food Cuspal inclination facilitates bilateral balance in various eccentric occlusions Cusp teeth provides resistance to rotation in relation to each other and to there bases Esthetically acceptable
  12. 12. Disadvantages Mandatory to use adjustable articulators Eccentric records must be made for articulator adjustment The bases need prompt and frequent refitting to keep the occlusion stable and balanced Cusp inclinations generate more horizontal forces
  13. 13. Selection of posterior teeth History Anatomic teeth of 33º or more Modified anatomic teeth between 30º and 0º Non-anatomic or zero degree teeth
  14. 14. Anatomic teeth  1913  Gysi  Trubyte
  15. 15.  1932  Pilkington & Turner  30 degree
  16. 16. Non-anatomic teeth Advantages: Area of freedom Poor neuromuscular control Horizontal forces Simple technique and articulator
  17. 17. Disadvantages Esthetically inferior Inefficiency in mastication
  18. 18.  Victor & Sears  1922-chewing members  1927-Channel type posteriors  Unlimited protrusive guide
  19. 19.  1927  Gysi  Crossbite teeth
  20. 20.  1930  Avery brothers  Scissor bite technique
  21. 21.  1936  McGrane  Curved cusp posteriors
  22. 22.  1935  French  Axial occlusal forces directed lingually
  23. 23.  1937  McPleasure  Lower bicuspid in reverse curve  First molar flat  Second in Monson curve
  24. 24.  1942  John Vincent  Metal inserts in resin posteriors
  25. 25. 1941 S. H. Payne Lingualised occlusion
  26. 26.  1961  M. Phylip Sosin  Crossblades of vitalium
  27. 27.  1977  Levin  Modified Sosin’s scheme by reducing the size of the cross blades to maxillary lingual cusp for esthetics
  28. 28. Non-anatomic or zero degree teeth  1929  Hall  Inverted cusp tooth
  29. 29.  1929  Myerson  True cusp  Series of transverse buccal-lingual ridges with sluiceways between them
  30. 30.  1934  Nelson  Chopping block posteriors
  31. 31.  1939  Swenaon  Non-lock
  32. 32.  1946  Hardy  Vitallium occlusal teeth
  33. 33.  1951  Myerson  Shear cusp tooth  First cross lnnked
  34. 34.  1952  Cook  Coe Masticators 1957 Cutter bar Upper porcelain cuspless teeth with a metal cutting bar
  35. 35. 1967 Frush Linear occlusal concept
  36. 36. Theories of occlusion  Theries of occlusion as related to the designs of articulators Bonwill’s theory of occlusion Conical theory of occlusion Spherical theory of occlusion  balanced occlusion theory Unilateral lever balance Unilateral occlusal balance Bilateral occlusal balance Protrusive occlusal balance
  37. 37. Bonwills theory of occlusion  1885  Theory of equilateral triangle  Equilateral triangle with 10 cm (4 inch) sides connecting both condyles and mesioincisal angles of the mandibular central incisor  Bonwil articulator
  38. 38. Conical theory of occlusion  Lower teeth move over the surface of the upper teeth as over the surface of a cone with a generating angle of 45º and with a central axis of the cone tipped at a 15º angle to the occlusal plane Hall automatic articulator by R.E.Hall
  39. 39. Spherical theory of occlusion  G. S. Monson (1918)  Based on observations by Von Spee  Lower teeth moving over the surface of upper teeth as a surface of a sphere on a diameter of 8 inches with centre in the region of Glabella.  Maxillomandibular instrument by Monson
  40. 40. Axioms for balance  Wider & larger the ridge and closer the teeth to the ridge, greater the lever balance vice versa  Wider the ridge and the narrower the teeth greater the balance and vice versa  More lingual the teeth arrangement in relation to the ridge crest, greater the balance and vice versa  More centered the occlusal force anteroposteriorly, greater the stability of base
  41. 41. Balanced occlusion theory  Unilateral lever balance (Equilibration of base)  Bilateral lever balance  Bilateral occlusal balance  Protrusive occlusal balance
  42. 42. Development of balanced occlusion Concept Definition Rationale Goals
  43. 43. Concept Von Spee (1890)- curve of Spee- masticatory surfaces of the molars are aligned in downward convex curve along the upper jaw and in an upward concave curve along the lower jaw Alfred Gysy (1910)- condylar path follows curved line or an S shaped curve
  44. 44.  B. B. McCollum (1926)-completely balanced occlusion for natural dentition  Clyde H. Schuyler (1929)- non-working side contacts may be contributing factors to traumatic injury  Balanced occlusion good theory for complete denture
  45. 45. Definition 1. Bilateral simultanious anterior and posterior contacts of the teeth in centric and eccentric position –(GPT 8) 2. Stable, simultaneous contact of the opposing upper and lower teeth in centric relation position and a continuous smooth bilateral gliding from this position to any eccentric positions within the normal range of mandibular functions (Winkler)
  46. 46. Rationale  Stabilization of denture  Combination of tissue resiliency and denture movement during function accounts for thee high frequency of non chewing or balancing side contacts. Denture movement regardless of posterior occlusal form  Shepperd(1964)- enter bolus enter balance  Prime- enter bolus exit balance-value of smooth gliding non-interfering bilateral tooth contact
  47. 47. Breumer & Hudson (1961)-complete denture do contact at times during mastication. Bilateral balance is even more important during swallowing saliva, closing to reseat denture, bruxing of teeth during stress Do not upset the normal, static, stable and retentive movement of denture Ensures even pressure in all pressure in all parts of the arch
  48. 48. Goals of balanced occlusion Maximum simultanious bilateral contact in centric relation Working side contacts all along the working side from cuspides posteriorly Balancing in molar region in lateral position , one contact is sufficient Occlusal plane parallel to the maxillary & mandibular residual ridge
  49. 49. Balancing in protrusive position require tipping of distal end of mandibular second molar up so that mesiolingual cusp of maxillary second molar will contact the distal marginal ridge of mandibular second molar Compensating curve for protrusive balance created buy tipping the second premolar distally, depressing the mandibular first molar,and placing upword inclination on the mandibular second molar
  50. 50. Laws of protrusive occlusion  Hanau’s study was pioneer explanation  Hanau’s laws of articulation and the Hanau Quint 1.Horizontal condylar inclination 2.Compensating curve 3.Prtrusive incisal guidance 4.Plane of orientation 5.Buccolingual inclination of tooth axis 6.Sagital condylar pathway 7.Sagital incisal guidance 8.Tooth alignment 9.Relative cusp hight
  51. 51. Condylar guidance Compensating curve Relative cusp height Incisal guidance Plane of orientation
  52. 52. Inclination of condylar guidance  Condylar guidance is the guiding influence which is furnished to the condyles by the temporomandibular articulation during essentric jaw movements  One factor which is present in edentulous jaw  Can not modified by edentulous jaw
  53. 53. Inclination of incisal guidance  Guding influence which results from positional relationships of the upper and lower anterior teeth when the mandible ,moved into eccentric relations to the maxillary while anterior teeth remain in contact  Angle in sagittal plane between incisal edges of the upper and lower incisar teeth when closed in centric occlusion
  54. 54.  Should be as flat as esthetics and phonetics will permit  Steep vertical overlap places the rotational centre below the posterior of the mandible and shallow above
  55. 55. Orientation of the occlusal plane Vertical location of the anteroposterior alignment of the occlusal plane in the space between the Camper’s line to a point, not at the superior border, but at the centre of the ear (Hanau)  Camper’s plane is not only misunderstood but also unreliable
  56. 56. Cephalometrically progrmmed adjustable plane Porion Nasion Anterior nasal spine Y= 83.4307-(0.9907-X) Where X= PoNANS angle value Y= best computed value of the occlusal plane
  57. 57. Inclination of the cusp Angle between the total occlusal surfaces of the tooth and inclination of the cusp in relation to that surface
  58. 58. Swenson’s formula Cusp inclination = Incisal inclination + fraction of distance from incisal guidance Σ = v + d ( B – v )
  59. 59. If inclination of the incisal guidance is equal to the condylar guidance v = B Then Σ = v + B
  60. 60. Gysi’s formula for the second molar condylar guidance inclination M2 = Incisal guidance inclination 2 + B + v 2 EM2 =
  61. 61. Prominence of the compensating curve  The anteroposterior and lateral curvature in the alignment of the occlusal surfaces and the incisal edges of artificial teeth which is used to develop balanced occlusion  It is determined by the inclination of posterior teeth and there vertical relationship to the occlusal plane so that the occlusal surface results in a curve that is in a harmony with the movemnt of the mandible as guided by the condylar path
  62. 62. Thielemann’s formula Balance d occlusio n = K. I. O.P. C. OK. K the inclination of condylar path I the inclination of incisal guidance C height of the cusp OP inclination of the plane of orientation OK prominance of the compensating
  63. 63. Cusp plane and cusp plane angle Cusp plane- when two buccal cusps tips and the highest situated lingual cusp cusp tip are connected form a cusp plane Cusp plane angle- the inclination of the cusp plane to the plane of occlusionis called “cusp plane angle”
  64. 64. Compensating curve formula C = Σ - w Σ Cusp angulation w cusp plane angle
  65. 65. Hanau’s Quint
  66. 66. Trapozzano concept Eliminated plane of orientation Compensating curve inclination
  67. 67. Boucher’s concept Three fixed factors Compensating curve is also important Both the cusp height and & the compensating curve are means for solving the problems imposed by the Christensen’s phenomena Occlusal plane shoud be located according to esthetic appearance and soft tissue anatomy
  68. 68. The Lott concept Divided five factors in clear and simple chart
  69. 69. Levin’s concept Eliminates the plane of orientation
  70. 70. Arrangement of anatomic artificial teeth into balanced occlusion
  71. 71. Arrangement of nonanatomic teeth into balanced occlusion
  72. 72. Centre of rotation A line drawn at right angle to the buccal incline of mandibular lingual cusp on the working side and another line at right angle to the lingual surfaces of mandibular buccal cusp on the balancing side meet at B
  73. 73. Influence of incisal and condylar guidance on the working and balancing side Working side inclines are not so steep as balancing side contacts Angle of inclination on the working side is less in posterior area and greater towards the incisal area Since incisal guidance is 30 degree, a smaller degree of angulation is seen in the posterior region which gradually increases towards 30 degrees the incisal area is approached
  74. 74. Concepts of occlusion Neutrocentric Lingualized occlusion Monoplane concept of occlusion Lineal occlusal concept
  75. 75. Neutrocentric concept De Van Neutralization of inclines Centralization of occlusal forces acting on the denture foundation Teeth should be placed where they grew as long as mechanical laws are not violated Factors such as orientation of occlusal plane, compensating curve, incisal guidance must be neutralized before neutralization of
  76. 76. Elements of neutrocentric concept 1.1. PositionPosition posterior teeth over the posterior residualposterior teeth over the posterior residual ridge as far lingually as tongue wouldridge as far lingually as tongue would allow so that forces would beallow so that forces would be perpendicular to the support areasperpendicular to the support areas
  77. 77. Proportion- Devan reduced tooth width by 40% to correct tooth proportion thus reduce vertical stress on the ridge Also horizontal and shearing stress was reduced because friction between opposing surfaces was decreased;such frictional forces are resisted by the o
  78. 78. Pitch Inclination or tilt Pitch as found in natural dentition Parallel to the maxillary and mandibular bases In natural dentition pitch of posteriors is determined by 1.Orientation of occlusal plane in reference to the condylar guidance 2.The steepness of compensating curve
  79. 79. Form Flat teeth with no deflecting inclines Reduction of destructive lateral forces
  80. 80. Number  Number is reduced from 8 to 6  Thus decreased magnitude of the occlusal force and centralised it to second premolar & first premolar area  Aids in stabilityby freeing the lower molar incline of occlusion
  81. 81. There should be no hesitancy in reducing the number of teeth. Krogman, the Anthropologist-the human dental formula of 2-1-2-3 is evolving into the formula 1-1-1-2
  82. 82. Lingualised occlusion Occlusal scheme which uses maxillary lingual cusps as the major functioning occlusal element occluding with nonanatomic or semianatomic teeth in the lower arch Payne- first suggested Pound- used the term
  83. 83. Indications  High priority on esthetics but the nonanatomic occlusal scheme is indicated by oral conditions such as sever resorption, class 2 jaw relationship or desplaceable supporting tissue  Complete denture opposed by a removable partial denture
  84. 84. Principles Anatomic posterior teeth in maxillary denture Non anatomic or semianatomic in mandibular denture Selective grinding of mandibular posterior teeth creates slight concavity on the occlusal surfaces Maxillary lingual cusp contacting mandibular teeth in working, balancing as well as protrusive movements
  85. 85. Monoplane concept of occlusion  Sear (1949) & Devan (1984)  Anterior teeth without vertical overlap, normal horizontal overlap  From 0 mm for class 3 to 12 mm for sever class 2  Occlusal plane- anterior point- incisal edges of canine posterior point- a) equal division of space b) parallel to mean foundation c)2/3rd way up of retromolar pad
  86. 86. Line from distoincisal edges of canine to buccolingual centre of retromolar pad on mandibular wax rim Upper premolars and first molars arranged in such a way that there central grooves coincide with the line Upper molar 2 mm above the occlusal
  87. 87. Lineal occlusal concept  A straight line of points or knife edges contacts on artificial teeth in one arch occluding non-anatomic teeth in opposing arch  Smallest lateral component of force  Since the area of occlusal contacts are minimal, frictional resistance is reduced  No change in location of contacts
  88. 88. Locating the line of occlusal contacts  Stabilization of mandibular denture- with the ridge of occlusal contacts in mandibular arch, occlusal forses in any jaw position will be applied to the mandibular denture at the same point  Esthetics- nonanatomic maxillary first premolar contoured to the anatomically and esthetically pleasant anatomic maxillary teeth with lingual cisps in straight line and keeping baccal cusps out of contacts
  89. 89. Combination of occlusal forms Non-anatomic maxillary porcelain teeth opposing mandibular porcelain teeth  least wear, hence in young healthy patient with adequate interridge distance  earlier occlusal disharmonies as porcelain does not wear fast enough to keep up with changes of the residual ridge
  90. 90.  Non-anatomic maxillary plastic teeth opposing mandibular plastic lineal teeth  Susceptibility to wear  Lineal becomes flat plane type  Contraindicated in young patients and patients with bruxism and abrasive diet  Advantageous in patientas with resorbed ridges and poor muscle function and who need treatment dentures for rapidly deterioring ridges
  91. 91. Nonanatomic maxillary plastic teeth opposing mandiblar porcelain lineal teeth More self adjusting as mouth changes occur Necessity to reshape maxillary posterior teeth
  92. 92. Anatomic maxillary porcelain teeth opposing non-anatomic mandibular plastic teeth Esthetics Line of contact between lingual cusps of maxillary porcelain teeth and non-anatomic mandibular posterior teeth
  93. 93.  Tooth positioning for lineal occlusion  Anterior teeth with no vertical overlap interferance  Posteriorly as high as practical to aid in developing protrusive balancing contacts with flat plane of occlusion  Lower teeth set first and centered over the crest of the ridge  Flat surfaces of maxillary posterior teeth parellel to cross arch horizontal plane
  94. 94. Discussion  Various contravercies in various concepts, theories and philosophies  Occlusion is a part of stomatognathic system and not just setting of teeth  occlusion in complete denture if based on unsound principles, actually worsens the physical, mental and social condition of old patients rather than improving it  There is nothing called ideal occlusion before the great variable Human factor
  95. 95. Summary and conclusion  Nature of supporting structures for complete denture and forces directed to them by creates a special type of problem  Biologic, physiologic and mechanical principles need to be considered and carefully coordinated in this new man made occlusion  First concern is for the health and preservation of the supporting structures.  Apply all factors that favor the stability of base and design the occlusion to function optimally in relation to the forces of mastication.
  96. 96.