Occlusion in fpd seminar

Occlusion in fpd seminar

1. Occlusion In Fixed Partial Dentures Department of Prosthodontics Including Crown & Bridge, Maxillofacial Prosthodontics & Oral Implantology . 1 Presenter- Dr. Nikita Aggarwal Preceptor- Dr. Siddhi Tripathi 6 th of May 2020

2. Contents Introduction Evolution of Occlusion Theories of Occlusion Classification Concepts of Occlusion - bilateral balanced unilateral balanced - mutually protected 2

3. Curves of occlusion Determinants of occlusion -vertical -horizontal Occlusal relation btw centric cusps and opposing teeth Interferences Pathologic occlusion Selective grinding for occlusal equilibration Conclusion References 3

4. Introduction 4

5. DEFINITIONS 1 5 1.Glossary of Prosthodontic Terms, Edition Nine, J Prosthet Dent 2017;117 (5S):e1-e105

6. 6 2. Guichet NF ,  Gourion G ,  Gauthier G . Rev Fr Odontostomatol.  Gnathology--why and how? The occlusion syndrome. Dec;17(10):1375-84.

7. Evolution of occlusion 3 7 3. KARNATI, PRAVEEN KUMAR & Reddy, Vivek & Chaitanya, Nellore. Functional occlusion and temperomandibular joint. Annals and Essences of Dentistry 2014;6(2):51-55

8. Development of the concept of the occlusion is divided into three periods as 8

9. 1. THE FICTIONAL PERIOD Pioneers like Fuller, Clark and Imric talked of antagonism, meeting or gliding of teeth. Kingsley wrote in 1880 about peculiarities of the permanent teeth Eugene Talbot’s text “Irregularities of the teeth and their treatment” 9

10. 2. THE HYPOTHETICAL PERIOD 10

11. 3. THE FACTUAL PERIOD HOLLY BROADBENT (1930) - accurate technique of Roentgenographic Cephalometry. PLANER - told when bites should be opened and when they should not, depending on the amount of space between two positions. In the past 40yrs or since 1930, a third element of occlusion, “Time” has received more attention. 11

12. As related to the designs of articulators- 1. Bonwill’s theory of occlusion 2. Conical theory of occlusion 3. Spherical theory of occlusion THEORIES OF OCCLUSION 12

13. Bonwills theory of occlusion In 1858- triangular theory- distance from the incisal edges of the lower incisors to each condyle is 4 inches, and the distance between the condyles is 4 inches 4 . Proposed concept of bilateral balanced occlusion Developed articulator that applied his 4-inch triangular theory. 13 4” 4” BONWILL 1858 4. Christensen, F. T. (1959).  The effect of Bonwill’s triangle on complete dentures. The Journal of Prosthetic Dentistry, 9(5), 791–796  

14. 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 www.asiandentalacademy.org

15. The Spherical Theory of occlusion Before 1916 Monson formulated a three-dimensional occlusal philosophy by combining the concepts of Bonwill's 4-inch triangle and bilateral balanced occlusion, Von Spee's compensating curve, and the observations of Balkwill and Christensen on condylar movement. This occlusal model was named the Spherical Theory. 15

16. The Spherical Theory of occlusion 16 Lower teeth moving over the surface of upper teeth as a surface of a sphere of a diameter of 8 inches with centre in the region of Glabella. Monson then developed an articulator for the

17. Dawson’s classification of occlusion 5 Type 1- Maximal intercuspation is in harmony with centric relation. Type IA: Maximal intercuspation occurs in harmony with adapted centric posture. The A signifies adapted condition. 17 5. Dawson E.P. Functional Occlusion From TMJ To Smile Design.1st Ed. St. Louis: Elsevier;2009. p. 107-109

18. Type II: Condyles must displace from a verifiable centric relation for maximum intercuspation to occur. Type IIA: Condyles must displace from an adapted centric posture for maximum intercuspation to occur. 18

19. Type III: Centric relation cannot be verified. Type IV: The occlusal relationship is in an active stage of progressive disorder because of pathologically unstable TMJs. 19

20. 20 6 6.

21. BILATERAL BALANCED OCCLUSION In 1935 , Schuyler developed the first detailed technique for occlusal adjustment . By 1953 he began to observe failure of natural dentition restored with balance .His observations and suggestions effectively signaled the end of BALANCE as a acceptable treatment approach for the dentulous patient Stuart and Stallard (1960) noted that balanced occlusion in reconstructed natural dentitions 1.Often required injudicious increase in occlusal vertical dimension to achieve balance. 2. Often led to instability of occlusion . 3. Frequently showed increased wear of teeth and restorations 21 The Demise of Balanced Occlusion in restoring natural dentition

22. Thus the concept of a unilaterally balanced occlusion (group function) evolved 22

23. Group Function Occlusion (Unilateral balanced occlusion) Schuyler (1929) Multiple contact relations be- tween the maxillary and mandibular teeth in lateral movements on the working-side whereby simultaneous contact of several teeth acts as a group to distribute occlusal forces 1 GPT-9 23 1. Glossary of Prosthodontic Terms, Edition Nine, J Prosthet Dent 2017;117 (5S):e1-e105

24. Here excursive contact occurs between all opposing posterior teeth on the laterotrusive (working) side only. On the mediotrusive (non-working) side, no contact occurs until the mandible has reached centric relation. 24 6 6

25. ADVANTAGES: Group function of the teeth on the working side distributes the occlusal load The absence of contact on the nonworking side prevents those from getting subjected to destructive ,obliquely directed forces found in nonworking interferences. 25

26. It also saves centric holding cusps that is mandibular buccal cusps and maxillary palatal cusps from excessive wear. In the presence of anterior bone loss or missing canines, mouth should be restored to group function Due to these factors, this concept has had broad support from PANKEY , MANN and SCHYLUER (1960) RAMJFORD,ASH(1966),POSSELT(1968),and LAURITZEN(1974). It has been adapted by PANKEY and MANN for complete mouth rehabilitation 26

27. Long centric(freedom from centric) 7 freedom to close the mandible either into centric relation or slightly anterior to it without varying the vertical dimension at the anterior teeth. Concern- restrictive effect that can result from the lingual inclines of upper anterior teeth 27 7. Dawson E.P. Functional Occlusion From TMJ To Smile Design.1st Ed. St. Louis: Elsevier;2009. p. 189-198

28. 28 According to Dawson in the absence of any CR interferences difference between centric closure and light closure from rest rarely exceeds 0.5mm,the usual long centric would be close to 0.2mm,and there are patients who do not require “long centric” at all because their light closure from rest is identical to their firm closure into CR.

29. Controversy ????? SCHUYLER Vs GUICHET 29

30. Disadvantages:- Group Function Occlusion doesn’t fulfill criteria for ideal occlusion. Guichet(1970) described standards for ideal occlusion and said that there was no one ideal occlusion pattern for all individuals but an appropriate pattern can be found based on these criteria. 30

31. Mutually Protected Occlusion (Organic occlusion) 31 6 6

32. Stallard found that anterior teeth protect posterior teeth and that the posterior teeth protect the anterior teeth . 32

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34. 34 6 6

35. 35

36. D’Amico (1958) performed a study on canines in animals and human beings and advocated a canine guided occlusion. This theory suggests that the only tooth contact in all positions of the mandible except CR should be between maxillary cuspids and mandibular cuspids . Thus he called canine as NATURE’S STRESS BREAKER Canine guided occlusion 36

37. WHY CANINE?? Long roots Good crown to root ratio Surrounded by dense compact bone which tolerates forces better. Location is far from the TMJ thus receiving less stress . It has many receptors in the periodontal ligament so it controls lateral pressure by directing vertical masticatory movements. 37

38. Plane of occlusion : 7 It refers to an imaginary surface that theoretically touches the incisal edges of the incisors and tips of the occluding surfaces of the posterior teeth. 38 7. Dawson PE. Functional occlusion from TMJ to smile design. Mosby; 2007:200-6

39. The curvatures of anterior teeth are determined by: Establishment of an esthetically correct smile line on the maxillary; and The relationship of the mandibular incisal edges to the anterior guidance & phonetics. 39 7. Dawson PE. Functional occlusion from TMJ to smile design. Mosby; 2007:200-6

40. 40 7. Dawson PE. Functional occlusion from TMJ to smile design. Mosby; 2007:200-6

41. Curve of Spee Purpose- To align each tooth for maximum resistance to functional loading, the long axis of each lower tooth is aligned nearly parallel to its individual arc of closure around the condylar axis. 41 7. Dawson PE. Functional occlusion from TMJ to smile design. Mosby; 2007:200-6

42. 42 7. Dawson PE. Evaluation, diagnosis and treatment of occlusal problems; p.190

43. Curve of Wilson 43 7. Dawson PE. Functional occlusion from TMJ to smile design. Mosby; 2007:200-6

44. Mediolateral curve Contacts the buccal and lingual cusp tips on each side of the arch. Results from inward inclination of the lower posterior teeth, making the lingual cusps lower than the buccal cusps on the mandibular arch; The buccal cusps are higher than the lingual cusps on the maxillary arch because of the outward inclination of the upper posterior teeth. 44 7. Dawson PE. Functional occlusion from TMJ to smile design. Mosby; 2007:200-6

45. There are two reasons for this inclination of posterior teeth: resistance to loading - Axial alignment of all posterior teeth is nearly parallel with the strong inward pull of the internal pterygoid muscles. masticatory function - easy access for the food to get to the occlusal table.(inward inclination of the lower occlusal table) (upper teeth positions the buccal cusps higher for easier access from the buccal corridor) 45 7. Dawson PE. Functional occlusion from TMJ to smile design. Mosby; 2007:200-6

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47. 47

48. Determinants of occlusion 8 48 Posterior controlling factor (CONDYLAR GUIDANCE) Anterior controlling factor (ANTERIOR GUIDANCE) 8. Okeson - Management of Temporomandibular Disorders and Occlusion, 7th Edition PG:86-99

49. Posterior controlling factor (CONDYLAR GUIDANCE) 49

50. As the condyle moves out of centric relation it descends along the articular eminence. If the articular eminence is steep, the condyle describes a steep vertically inclined path and if flatter, the path is less vertically inclined. The angle at which the condyle moves away from a horizontal reference plane is referred to as the CONDYLAR GUIDANCE ANGLE. 50

51. 51

52. Anterior controlling factor (Anterior guidance) 52

53. The anterior teeth guide the movement of the anterior portion of the mandible. As the mandible protrudes, the incisal edge of the mandibular anterior teeth occlude with the lingual surfaces of the maxillary anterior teeth. The steepness of the lingual surface determines the amount of vertical movement of the mandible. It is a variable factor. 53

54. VERTICAL DETERMINANTS 1. Effect of condylar guidance on cusp height 2. Effect of anterior guidance on cusp height 3. Effect of plane of occlusion on cusp height 4. Effect of curve of Spee on cusp height 54 Influence the height of the cusp & the depth of the fossae

55. Effect of condylar guidance on cusp height 55 STEEPER the articular eminence, more is the descent of the condyle, resulting in greater vertical movement. Thus allowing for STEEPER posterior cusps.

56. 56 Effect of anterior guidance on cusp height INCREASED HORIZONTAL OVERLAP decreases the anterior guidance angle. There is less vertical movement of the mandible leading to FLATTER POSTERIOR CUSPS.

57. 57 INCREASED VERTICAL OVERLAP increases the anterior guidance angle. There is more vertical movement of the mandible leading to STEEPER POSTERIOR CUSPS.

58. Effect of plane of occlusion on cusp height Plane of occlusion is an imaginary line touching the incisal edges of the maxillary anterior teeth and the cusps of the maxillary posterior teeth. 58

59. The more parallel the plane of occlusion is to the condylar guide angle, the shorter the posterior cusps must be The more divergent the plane of occlusion is to the condylar guide angle, the taller the posterior cusps can be 59

60. Its degree of curvature influences the height of the posterior cusps. FLATTER the curve of Spee , greater is the angle away from the maxillary posteriors – TALLER cusp . More acute curve of Spee , smaller the angle of mandibular posterior tooth movement – flatter cusps . Effect of curve of spee on cusp height 60

61. EFFECT OF MANDIBULAR LATERAL TRANSLATION MOVEMENT ON CUSP HEIGHT 61 The greater the movement The shorter the posterior cusps The more superior the movement of the rotating condyle The shorter the posterior cusps The greater the immediate side shift The shorter the posterior cusps

62. HORIZONTAL DETERMINANTS 1. Effect of distance from the rotating condyle 2. Effect of distance from midsagittal plane Effect of distance from rotating condyle and fossa from midsagittal plane 4. Effect of mandibular lateral translation movement 5. Effect of intercondylar distance 62

63. Effect of distance from the rotating condyle INCREASED distance – wider angle between laterotrusive and mediotrusive pathways, FLATTER centric cusps. 63

64. Effect of distance from midsagittal plane INCREASED distance – wider angle between laterotrusive and mediotrusive pathways, FLATTER centric cusps 64

65. Effect of mandibular lateral translation movement Increased lateral movement, increases the angle between laterotrusive and mediotrusive pathways The direction of rotation of the rotating condyle also plays a role Lateral and anterior direction – Increased angle (flatter cusp) Lateral and posterior direction – decreased angle (sharper cusp) 65

66. Effect of intercondylar distance Increase in distance, reduces the angle between laterotrusive and mediotrusive pathways 66

67. Occlusal relationship between centric cusps and opposing teeth 67

68. Tooth – to tooth occlusion Cusp tip to fossa Cusp to fossa Tooth – to – two teeth occlusion Cusp marginal ridge/ cusp embrasure occlusion 68

69. Cusp to Fossa Occlusion 69

70. 70 4 upper centric cusps - mesiolingual cusp of molars & palatal of the premolars 2 lower centric cusps – distobuccal cusps of the molars

71. 71 Cusp to Embrasure Occlusion Also called CUSP MARGINAL RIDGE OCCLUSION/ TOOTH TO TWO TOOTH OCCLUSION/ TWO POINT CONTACT : One tooth occludes with two opposing teeth Found in 95% of all adults with natural dentition . The centric cusp occludes in opposing embrasures contacting the marginal ridges of opposing pair of teeth.

72. 2 upper centric cusps - disto -lingual cusp of the molars 72

73. 4 lower centric cusps- buccal cusps of the premolars and mesiobuccal of the molars 73

74. 74 9 9

75. 75 Four types of interferences Centric Interference Working Interference Non Working Interference Protrusive Interference

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78. 78 6

79. Selective Grinding for Occlusal Equilibration 7 79 7. Dawson E.P. Functional Occlusion From TMJ To Smile Design.1st Ed. St. Louis: Elsevier;2009. p. 189-198

80. Equilibration procedures 80 Reduction of interferences in Centric Relation Elimination of all posterior interferences during protrusive excursions Harmonization of anterior guidance Selective reduction of interferences in lateral excursions

81. centric relation interferences can be differentiated into two types: 81

82. Interference to the arc of closure 82 As the condyles rotate on their centric relation axis, each lower tooth follows an arc of closure Any interference  condyles displaced downward and forward  anterior slide

83. Basic grinding rule to correct anterior slide 83 Mesial inclines of maxillary teeth OR distal inclines of mandibular teeth MUDL

84. Interference to the line of closure 84 Primary interferences that cause the mandible to deviate to left or right from first point of contact in CR to most closed position

85. Basic grinding rules 85 1. If the interfering incline causes the mandible to deviate off the line of closure toward the cheek , grind the buccal incline of maxillary or lingual incline of mandibular or both BULL

86. 86 2. If the interfering incline causes the mandible to deviate off the line of closure toward the tongue , grind the lingual incline of maxillary or buccal incline of mandibular or both LUBL

87. Grinding Rules Rule 1: Narrow stamp cusps before reshaping fossae 87 Stamp cusp is the cusp that fits inside the fossa- Lower buccal Upper lingual cusp

88. Rule 2: Don’t shorten a stamp cusp The cusps should be narrowed on the side that marks when the jaw closes to centric relation contact If interferences that deviate the mandible forward are eliminated, a “long centric” will be provided automatically 88

89. Rule 3: Adjust centric interferences first 89

90. Rule 4: Eliminate all posterior incline contacts. Preserve cusp tips only. 90

91. Lateral Excursion Interferences 91 dictated by two determinants: 1. The border movements of the condyles 2. The anterior guidance When lateral excursions are being equilibrated, the mandible must be guided with firm upward pressure through the condyles to ensure that all interferences are recorded and eliminated through the uppermost ranges of motion that can occur at true border paths for both the condyles and the an- terior guidance.

92. Next step: Eliminating Excursive Interferences protrusive interferences, interferences of the working side interferences of the balancing side Can be marked and adjusted without concern for whether the interference is in protrusive, lateral working side, or balancing side. 92 The ideal pattern of centric relation contacts.

93. perfected occlusion Dots in back . . . lines in front. This is the ideal result of marking with a red ribbon while the patient grinds the teeth together in all excursions. All teeth touch in centric relation. Only the anterior teeth contact in excursion. 93

94. A typical pattern of markings when a red ribbon is placed and the patient is instructed to grind the teeth together. note the posterior interferences prevent any excursive contact on the anterior teeth Grind all red marks on posterior teeth. Do not touch any black marks. 94 armamentarium : A small diamond wheel stone, 12-sided football-shaped finishing bur work well for precise reduction and reshaping. Red and black marking ribbons are held in Miller ribbon holders.

95. 95 Marks that might look insignificant can be potent triggers for activating muscle hyperactivity and can prevent the turning off of the elevator muscles that occurs when posterior disclusion is complete. Such interferences can easily be eliminated, and must be, for a predictably successful result.

96. Adjusting the Anterior Guidance Step 1. guided closure. Step 2. light tapping from a postural position. Use a red marking ribbon for light postural closure . Then use a black ribbon for centric (guided) closure . If red marks extend onto a fairly steep incline, reduce the incline just enough to permit unguided closure without wedging into the incline before fully closed. Step 3. Equalize contact in the protrusive path . If a single tooth is carrying 100 percent of the forces when the mandible slides forward, reduce the incline as needed to bring more incisors into contact in protrusive. Step 4. Adjust the lateral anterio r guidance as needed to permit smooth, comfortable excursions. 96

97. 97

98. Protrusive Interferences DUML: Grind the Distal inclines of the Upper or, in some instances, the Mesial incline of the Lower teeth. “slide forward and back, forward and back.” from centric The patient should do the sliding, but the dentist should maintain a firm hold on the mandible to make sure the condyles are staying up against the eminentiae during the movement. 98 DUML

99. VERIFICATION OF COMPLETION 99

100. OCCLUSION INDICATORS – TYPES 10 100 10. Ramakrishna Rajan Babu , Sanjna Vibhu Nayar . Occlusion indicators: A review. J Indian Prosthodont Soc. 2007;7(4):170-174

101. 101 Articulating paper: Hydrophobic Their basic constituents are a coloring agent and a bonding agent (e.g., Transculase -Bausch Articulating paper) In practice, there is a tendency to use cost-effective materials such as carbon papers . These are made up of hydrophobic waxes that tend to smudge the tooth surface and fail to mark the contact spots clearly. Metallic shim stock film: The shim stock film has a metallic surface on one side and the other side is colour coded. It is mainly indicated for use in the occlusal splint therapy in order to accurately mark the contacts on the soft splint in the laboratory. Articulating film: The Artifol articulating film(Bausch Inc.) has only a thickness of 8 μ, It is made up of a emulsion with a thickness of 6 μ, which is hydrophobic and contained inside a polyester film. It must be used with special holders in a dry environment. It is universally applicable, both intraorally and on lab models.

102. 102 Bausch pdf Based on thickness -Ultra-thick- 200 micron plus- mostly not used -Thick -41-100 microns- removable prosthodontics, glazed /metal surfaces -Thin -19-40 microns- natural dentition, bisque trial -Ultra-thin -8-12 microns- foils- shimstock , artifoil - implant prosthesis ( as not pdl ), check presense or tightness of proximal contacts, friction on intaglio surface of crowns Dr. Moez Khakiani , youtube

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104. First -1987 consists of a thin flexible sensor inserted into an autoclavable sensor handle that is plugged into the USB port of a personal computer. The sensors are 85 microns thick, it encloses a double layer of Mylar, a special ink. A force applied to each of these cells modifies the electric conductivity of the Mylar. The program records and analyzes the differentials of applied voltage, and gives relative values of the force and duration of occlusal contacts, with a time precision of 10 ms. Developed by Maness, 1987 T- Scan 10 10. Ramakrishna Rajan Babu , Sanjna Vibhu Nayar . Occlusion indicators: A review. J Indian Prosthodont Soc. 2007;7(4):170-174

105. - accurate way to determine and evaluate the time sequence and force of occlusal contacts by converting the qualitative data into quantitative and displaying them digitally - analyzing tooth contacts in order to improve TMD and removing the causes of disorders. 105 Digital force data 2D and 3D

106. Conclusion There is no one answer to occlusal problems, the dentist should use the philosophy that works best in his own hands and at the same time do the most good, or better yet, the least harm to the patient.”   106

107. REFERENCES 107

108. 1.Glossary of Prosthodontic Terms, Edition Nine, J Prosthet Dent 2017;117 (5S):e1-e105 2. Guichet NF ,  Gourion G ,  Gauthier G . Rev Fr Odontostomatol.  Gnathology--why and how? The occlusion syndrome. Dec;17(10):1375-84. 3. KARNATI, PRAVEEN KUMAR & Reddy, Vivek & Chaitanya, Nellore. Functional occlusion and temperomandibular joint. Annals and Essences of Dentistry 2014;6(2):51-55 4. Christensen, F. T. (1959).  The effect of Bonwill’s triangle on complete dentures. The Journal of Prosthetic Dentistry, 9(5), 791–796   5. Dawson E.P. Functional Occlusion From TMJ To Smile Design.1st Ed. St. Louis: Elsevier;2009. p. 107-109 6. Rosensteil SF, Land MF, FujimotoJ . Contemporary Fixed Prosthodontics. 3 RD ed. St. Louis:Elsevier;2000.p.110-144 7. Dawson E.P. Functional Occlusion From TMJ To Smile Design.1st Ed. St. Louis: Elsevier;2009. p. 189-198 8. Okeson - Management of Temporomandibular Disorders and Occlusion, 7th Edition PG:86-99 9. Shillingburg HT, Hobo S, Whitsett LD, Jacobi R, Brakett SE. Shillinburg's Fundamentals Of Fixed Prosthodontics.4th ed. Chicago: quintessence;2012 10. Ramakrishna Rajan Babu , Sanjna Vibhu Nayar . Occlusion indicators: A review. J Indian Prosthodont Soc. 2007;7(4):170-174 108

109. Tilted teeth if the mark on the upper tooth is lingual to the central fossa and if stability can be improved, the lower cusp tip is moved toward the buccal, and the lower cusp is reshaped by grinding its lingual inclines to move the contact buccally. This should not be done if it will require shortening of the cusp out of centric contact . To grind the up- per tooth only may mutilate its lingual cusp unnecessarily without improving the direction of forces. 109