8 - setting of teeth for class I, II and II arch relation ship (Edited)

Prosthetic Problems and possible solutions in Setting –up
of teeth for skeletal Class II and Class III arch relationship
of completely edentulous patients
Prof. Amal F. Kaddah

1. Prosthetic Problems and possible solutions in Setting –up of teeth for skeletal Class II and Class III arch relationship of completely edentulous patients

2. Prof. Amal Fathy Kaddah Dr. Mohamaed Kandel Prosthodontic Department, Faculty of Oral &Dental Medicine, Cairo University Setting-up of Artificial Teeth For Class II and Class III Arch relationship Dr. Marwa Anas El- Wegoud Dr. Mohamed Adel Dr. Mohamed Esawi Dr. Ramy kalaifa Dr. Mariam Ahmed Roshdy Dr. Heba Salama Dr. Samah Ahmed Dr. Abobakir abasho

3. When you realize you've made a mistake, take immediate steps to correct it.

4. Contents: I-Introduction II-Factors affecting teeth arrangement Pattern of bone resorption Esthetics and phonetics requirements. Stability Occlusal plane Arch form ( Arrangement of teeth in harmony with ridge contour) Interdigitation of the teeth The inclination for proper occlusion Arch relationship III- Guidelines governing the position of artificial teeth IV- Arrangement of teeth in normal cases. V- Atypical arrangement of teeth (Class II, Class II) VI- Common errors in teeth setting.

5. Guidelines for arrangement of teeth A- Key of occlusion Canine key of occlusion Molar key of occlusion B- Anatomical landmarks C- The normal Overjet & overbite

6. Identifying the problem Through: 1) Clinical examination Extra-oral & intra-oral 2) Diagnostic bite record and mounting on articulators 3) Radiograp hic analysis

7. Introduction According to the relation between the bones of the face and the jaws, facial skeletal pattern is classified into: Angle’s classification of the facial skeletal pattern

8. Introduction The selection of teeth for edentulous patients requires a knowledge and understanding of some physical, biological and mechanical factors. Any choice of artificial teeth must be considered as a preliminary selection until the teeth are arranged on trial denture bases and viewed in the patient’s mouth. The teeth are not only an important component of facial appeal, they give each face a unique identity and make it easily recognized ( Important factor for denture success ).

9. NORMAL OCCLUSION The mesial incline of the maxillary canine occludes with the distal incline of the mandibular canine. The distal incline of the maxillary canine occludes with the mesial incline of the mandibular first premolar. Normal Line of Occlusion , normal smooth curves. normal overbite and overjet and coincident maxillary and mandibular midlines. Molar Relationship: According to Angle, the mesiobuccal cusp of the maxillary first molar aligns with the buccal groove of the mandibular first molar. Canine Relationship: The maxillary canine occludes with the distal half of the mandibular canine and the mesial half of the mandibular first premolar .

10. Class I Malocclusion Molar Relationship and Canine Relationship as normal occlusion, but Line of Occlusion: ALTERED in the maxillary and mandibular arches Individual tooth irregularities (crowding/spacing/other localized tooth problems). Inter-arch problems ( open bite/ deep bite/cross bite). Mesognathic : normal, straight face profile with flat facial appearance.

11. Molar relationship : The molar relationship shows the mesiobuccal groove of the mandibular first molar is DISTALLY (posteriorly) positioned when in occlusion with the mesiobuccal cusp of the maxillary first molar.  Usually the mesiobuccal cusp of maxillary first molar rests in between the first mandibular molar and second premolar. Class II malocclusion Canine Relationship : The mesial incline of the maxillary canine occludes ANTERIORLY with the distal incline of the mandibular canine. The distal surface of the mandibular canine is POSTERIOR to the mesial surface of the maxillary canine by at least the width of a premolar.

12. CLASS II DIVISION 2 Condition when class II molar relationship is present with retroclined upper central incisors, upper lateral incisors may be proclined or normally inclined. Overjet is usually minimal CLASS II DIVISION 1 Condition when class II molar relationship is present with proclined upper central incisors. There is an increase in overjet . CLASS II SUB-DIVISION Condition when the class II molar relationship exists on only one side with normal molar relationship on the other side.

13. TRUE class III malocclusion ( SKELETAL) which is genetic in origin due to excessively large mandible or smaller than normal maxilla. The mesiobuccal cusp of the lower fist molar occludes mesial to the class I position Class III malocclusion has 3 subdivisions :

14. (FALSE or postural) which occurs when mandible shifts anteriorly during final stages of closure due to premature contact of incisors or the canines . It’s also known as postural class III. Forward movement of the mandible during jaw closure can also result from  premature loss of deciduous posterior teeth . 2- PSEUDO Class III malocclusion

15. 3- Class III Sub-division : Class III molar relationship exists on one side and the other side as a normal Class I molar relationship.

16. Certain rules and principles that should be followed during managing complete denture cases

17. In the cases with abnormal arch relationships, The relationship cannot be changed by setting up the teeth, and any attempt to make the occlusion normal in abnormal arch relationships would compromise esthetics, phonetics and function. In the cases with abnormal arch relationships, treatment should be restored in the Centric relation . Positions other than centric relation are not repeatable However, some modifications during setting-up are necessary.

18. Mandibular posterior denture teeth must be placed over the lower residual ridge, and adjustments made with the maxillary occlusal table. The horizontal relations to the residual ridges The vertical positions of the occlusal surfaces and incisal edges between the residual ridges

19. Freedom of movement is a must during eccentric movements. Multiple occlusal contacts must be established in centric and eccentric positions whatever the occlusal scheme used. (with the use of Anatomic Teeth , a Steep Occlusal Plane , a More Pronounced Curve Of Spee , and with monoplane teeth use of a Balancing Ramp which is necessary for protrusive balance).

20. Whether the relation is class I,II or III, when setting up dentures, the upper and lower first molars must have the same relationship to each other as in an Angle class I. i . e: Upper mesio -buccal cusp of first molar has contact between the lower mesial buccal and buccal cusp of first molar. Note : in class III, reverse cusp fossa relationship could be done

21. class I class II class III

22. In the maxilla: After extraction of the teeth resorption of bone occurs vertically, labially and buccally , so it becomes small in size. In the mandible: bone resorption occurs vertically and lingually , so it becomes wide. By understanding this pattern setting of the anterior teeth should be inclined labial to the crest of the ridge to restore the natural position of the anterior teeth. Factors affecting setting of teeth 1- Pattern of bone resorption

23. 2- Esthetics and phonetics: Labial surface of teeth should support the lips. It's important to produce pleasant appearance and to simulate the natural teeth to a great extent.

24. 3- Role of The occlusal plane on Esthetics, phonetics and stability: a. Anterior teeth should be 2mm below the upper lip. b. In flat lower ridges, occlusal plane should be as close as possible to the ridge.

25. c. The horizontal relations to the residual ridges d. The vertical positions of the occlusal surfaces and incisal edges between the residual ridges

26. Factors must be considered : 1- Aesthetic base 2- Functional base (chewing and speech) 3- Physical and mechanical (leverage action and parallelism )

27. It is the ability of a denture to be firm, steady or constant, by functional stresses and not to be subjected to change of position when forces are applied . It is the ability of a denture to resist displacement by functional stresses. 4- Stability:

28. If the teeth are placed too far forward , they will displace the denture due to active lip muscles. If they are placed too lingualy , they can cause tongue crowding which also results in denture displacement during tongue movement . If placed too far buccally , the action of the buccinator muscles can dislodge the denture too.

29. The level of the occlusal plan should be below the level of the maximum convexity of the tongue to provide denture stability

30. VD CO # CR Uneven pressure Cuspal interference Teeth off ridge Tuberosity of opposite side In upper buccal sulcus of working side White sore area on the site of pressure VD (Neurological pain) VD (white patch) Occlusion

31. 5- Interdigitation of teeth Maximum interdigitation should be achieved. The upper and lower teeth should be set to have a definite cuspal relation to each other, in order to maintain both positional and functional relationship .

32. The maxillary arch: U-shaped form . While The mandibular arch: V-shaped form. 6- Arch form:

33. The arch form can be: Square Arch: Central incisors are in line with canines. Tapering Arch: Central incisors are at a greater distance forward than canines. Ovoid Arch: In between

34. According to the relation between the bones of the face and the jaws, facial skeletal pattern is classified into: 7- Jaw relationship

35. Factors governing the position of artificial teeth Guide lines governing the position of artificial teeth I- Key of occlusion Canine key of occlusion Molar key of occlusion II- Anatomical landmarks III- The normal Overjet & overbite

36. I-Key of occlusion : It denotes the relationship of upper and lower teeth during function. 1- Canine relationship: the mesial incline of the upper canine aligns with the distal incline of lower canine

37. 2- Molar relationship: The mesiobuccal cusp of maxillary first molar should aligns with the mesiobuccal groove of mandibular first molar. The mesiolingual cusp tip of mandibular first molar should fit into the central fossa of the upper first molar.

38. II. Anatomical Landmarks Incisive papilla as a guide 2) The canine lines 3) Midline 4) High Lip Line 5) Interpupillary line 6) Ala- Tragus line 7) Retromolar pad 8)The maxillary tuberosity

39. Try-in ???

40. The anteroposterior positioning of anterior teeth is important for esthetics and phonetics, because of the support that is provided to the lips, cheeks and other tissues of the oral cavity from the teeth. Anterior teeth Therefore, anterior artificial teeth should be placed in the same position or as close as possible to that occupied by the natural teeth to maintain natural patient appearance. II. Anatomical Landmarks 1) Incisive papilla as a guide

41. • Mark corners of mouth on wax occlusal rims. • A line perpendicular to midline of palate through distal border of incisive papilla. 1) Incisive papilla as a guide

42. The incisive papilla is a valuable guide for anterior teeth placement because it has a constant relationship to the natural central incisors. The labial surfaces of upper central incisors are 8-10 mm anterior (in front) of the middle of to the incisive papilla.

43. Incisive papilla as a guide The incisive papilla is situated on a transverse line passing through the tips of the canines in the dentate person.

44. 2) The canine lines: The six maxillary anterior teeth occupy the space between the distal of the right canine eminence and the distal of the left canine eminence. 3) Midline: A line drawn anteroposteriorly bisecting the midsagittal suture, incisive papilla and labial frenum coincide with the midline of upper dental arch.

45. Nose – Distance between tips of canine is same as width of base of nose A vertical line extending along the lateral surface of the ala often will pass through the middle of the natural upper canine.  Philtrum – Width of upper centrals, approximates the width of philtrum

46. 4- High Lip Line Highest point of upper lip when smiling Cervical necks lie at or above this line If shorter teeth are selected, esthetics compromised

47. Amount of teeth showing

48. 5) Interpupillary line : The occlusal plane of maxillary anterior teeth should be parallel to the interpupillary line. The posterior occlusal plane should be parallel to the ala-tragus line (from the ala of the nose to the tragus of the ear). 6) Ala- Tragus line

49. 7: It is the anatomic landmark used most frequently as a reference for teeth arrangement as it applies in three dimensions: vertically, laterally and anteroposteriorly . Laterally, it guides the buccolingual position of posterior teeth .

50. 7) Retromolar pad: Anteroposteriorly , no artificial teeth are placed posterior to the anterior boundary of the pad, to avoid having a tooth over an incline which results in denture sliding. The posterior occlusal plane should be at the level of 2/3 the height of retromolar pad. Fixed Position Measurable Identifiable Relationship to natural dentition Mesiodistal Width available.

51. Aligned Occlusal Groove The occlusal groove of the posterior teeth should lie on the straight line joining the distal arm or the tip of the canine anteriorly and the midpoint of the occlusal rim posteriorly.

52. The posterior teeth are generally placed to enhance the stability of the mandibular denture. The mandibular teeth should be arranged so that they are positioned over the crest of mandibular residual ridge. The Retro molar pad is used as a guideline to determine the buccolingual position.

53. Not to encroach on tongue space and buccal corridor.

54. 8)The maxillary tuberosity It lies immediately posterior to the maxillary second molar. Teeth should not be set on the tuberosity as it can lead to lever imbalance and cheek biting in posterior region.

55. Buccolingual Width Sufficient to act as a table to hold food. Less than width of natural teeth. Limits forces directed to ridge

56. Determined by available inter ridge space, occlusal plane and height of anterior teeth. Occluso -gingival Height

57. III- Overjet and overbite : The overjet is measured in horizontal plane while the overbite represents the vertical plane. Normal overjet should be: 1.5 mm Normal overbite should be: 0.5 mm

58. The horizontal overlap between upper and lower anterior teeth is automatically decided by the relation between the upper and lower residual ridges. The upper and lower anterior teeth shouldn't be in contact in centric occlusion .

59. 1-Arrangement of teeth for Normal arch relationship)

60. Arrangement of anterior teeth

61. The middle of the crest of the mandibular ridge should be recorded. Mark the midline of the patient’s face by placing a dot on the incisive papilla and marking this midline on the maxillary anterior land area, extending down the front of the cast. The incisive papilla is a much more reliable landmark for the midline than the labial frenum .

62. 1. Arranging the maxillary anterior teeth a. Maxillary central incisors The long axis of the tooth should incline slightly distally. The contact point should coincide with the midline of the face. The incisal edge should touch the mandibular occlusion rim. The facial surface of the central incisors should be 8-10 anterior to the center of the incisive papilla. The neck is slightly depressed.

63. b. Maxillary lateral incisors The long axis should inclined slightly distally. 2. The neck is more depressed. 3. The incisal edge of the lateral should be raised approximately 1 mm from the mandibular occlusion rim.

64. The canine tooth is an important tooth in any tooth arrangement because it forms the corner of dental arch . The incisal edge of the canine should touch the mandibular occlusion rim. 2. The long axis should be perpendicular or slightly inclined distally to the occlusal plane. The cervical third of the labial portion of the canine should incline buccally to achieve some prominence. 3. Distal aspect of the canine should coincide with the crest of the ridge.

65. Relations and inclinations of maxillary anterior teeth . Incisal views of anterior teeth showing their angle of rotation .

66. Lower central incisor Long axis should be set perpendicular to the occlusal plane. The neck of tooth should be slightly depressed. The incisal edge should form (1-2mm) horizontal and vertical overlap in respect with upper central incisor Lower lateral incisor: Long axis slightly inclined. The occlusal height should be the same as the central incisors. Lower canine: Long axis is nearly perpendicular to the occlusal plane The neck of tooth should be set prominent and the cusp tip 2mm above the occlusal plane .

67. N.B. Anterior teeth are set to follow the arch form of the patient's residual ridges. The incisal edges of the anterior teeth should be set to correspond to the shape of the arch.

68. Make a cut with a heated, sharp knife, at the midline in the anterior wax rim. Cut all the way to the baseplate . Make a similar cut just distal to the canine point. Remove this section of wax in its entirety.

69. Use a flat plate to position the central incisor so that it contacts the occlusal plane. Set the rest of the anterior teeth on the right side according to the curve defined by ( occlusal rim).

70. Use a flexible plastic ruler to verify that the incisal portion of the tooth’s labial surface is properly located and in contact with the anterior curvature of the occlusion rim.

71. An anterior view of the maxillary anterior teeth shows that only the lateral incisors do not touch the occlusal plane as recorded by mandibular wax rim.

72. Mark the midline of the mandibular ridge on the mandibular wax rim and cut out a section representing the right mandibular anterior teeth from the rim. Arrange the lower anterior teeth following the arch shape Position the teeth over the crest of the ridge.

73. Set the mandibular central incisors so that the maxillary incisors cover them, 1mm vertically and 1mm horizontally (1mm horizontal and vertical overlap) if you are using anatomic posterior teeth

74. Arrangement of posterior teeth

75. Upper first premolar The facial surface of 1 st premolar must harmonies with canine. Long axis of tooth perpendicular to the occlusal plane. Buccal and palatal cusps touch the occlusal plane Palatal cusp over crest of mandibular ridge Upper second premolar Long axis of tooth perpendicular to the occlusal plane. Palatal cusp is about 1 mm over the occlusal plane. Palatal cusp over crest of mandibular ridge

76. Upper first molar Mesiopalatal cusp touch the occlusal plane The facial surface 1 st molar must harmonies with 1 st and 2 nd premolar The distobuccal cusp is raised about 1/2 mm and the disto Palatal cusp is raised about 1/2 to 3/4 mm above the occlusal plane. Upper second molar All four cusps are above the occlusal plane The facial surface of 2 nd molar must harmonies with 1 st molar Cusps of the second molar are raised from the occlusal plane following the position of the first molar.

77. Remove the wax on one side of the maxillary baseplate . The rim is left intact on the opposite side because this will help you to maintain the location of the occlusal plane. Relation of maxillary posterior teeth to occlusal plane.

78. Set the teeth on the maxillary right side so that the mesiolingual cusp of the maxillary first molar rests in the central fossa of the mandibular first molar. Set the teeth so that the buccal surfaces of the premolar(s) and mesial cusp of the first molar line up with the mid- buccal surface of the canine. The distobuccal cusp of the first molar should deviate approximately 20 o from this plane and the second molar will fall along this plane.

79. Lower first premolar Long axis of tooth perpendicular to the occlusal plane. Buccal cusp above the occlusal plane Lingual cusp is below the occlusal plane. Lower second premolar Long axis of tooth perpendicular to the occlusal plane. Buccal and palatal cusps above the occlusal plane

80. Upper first molar All cusps above the occlusal plane Upper second molar All four cusps are above the occlusal plane

81. Remove enough wax to allow setting most of the posterior. Check the position of the teeth over the crest of the ridge .

82. Buccal cusp of the lower 1 st premolar contacts the mesial marginal ridge of the upper 1 st premolar. Buccal cusp of the lower 2 nd premolar contacts the fossa between two upper premolars. Mesiobuccal cusp of the lower 1 st molar occludes in the fossa between upper 2 nd premolar and 1 st molar. Mesiobuccal cusp of the lower 2 nd molar occludes in the fossa between upper 1 st and 2 nd molars.

83. 2- Arrangement of teeth for Class II arch relationship

84. Problems and possible solutions For Class II arch relationship

85. Problem >> Convex face profile resulting from a mandible that is too small or maxilla that is too large. class II

86. Distobuccal cusp of maxillary first molar falls on the mesio -buccal groove of mandibular first permanent molar. Class II It is divided into: Class II Div 1: Upper incisors are proclined Class II Div 2: Upper laterals overlap centrals and the centrals are retroclined

87. Prosthodontical problems in angle class II Problem in static relationship and functional relationship -Anterior Posteriorly Functional

88. Ridge is narrower than the upper and associated with a receding chin. Setting the upper teeth inside the ridge and lower teeth outside the ridge does not produce marked stability 3. Large overjet is preserved. Angulations of the upper teeth give the patient a rabbit appearance Angulations of the lower tend to unstabilise the denture Prosthodontical problems in angle class II

89. Possible solutions Modifications Done In Setting Up Of Teeth for Angle Class II Modifications Done In Posterior Teeth Morphology: SR Orthotyp Teeth

90. Modifications Done In Setting Up of Teeth for Angle Class II Anterior teeth arrangement 1- Vertical overlap should be kept as minimal as the esthetics and phonetics permit. 2-Maxillary anteriors are set-up with their incisal edges inclined more palatal than their necks. 3- Labial inclination of lower anteriors . 4- Leave out a lower central or lateral incisor, or overlap lower teeth.

91. Modifications Done In Setting Up of Teeth for Angle Class II 5. When retrusion is not extreme, Narrower lower anteriors . Slight spaces between the upper anterior teeth or Slight crowding of lower anterior teeth

92. 6. When it is too great and can not be fixed by modification of anterior teeth Remove lower first bicuspid

93. Angle’s Class II division 2 : If the overbite and minimal overjet of these cases is reproduced in an artificial tooth set-up, the patient could be locked into an impossible situation. So there needs to be some re-positioning of the teeth to reduce the overbite as much as possible without overly compromising aesthetics .

94. Slight labial inclination of lower anteriors + Slight lingual inclination of upper anteriors Slight spacing of upper anteriors or Slight crowding of lower anteriors

95. The incisal edge of the upper anteriors should point toward the lower mucolabial fold

96. Posterior teeth arrangement Non-anatomic teeth or teeth with shallow inclines are selected to reduce the stress on the weaker lower ridge. Eliminate lower 4 Upper posterior teeth can be placed slightly palatal to provide a working occlusal contact with the lower teeth.

97. The lower posterior teeth are placed over crest of the ridge. The upper teeth are then set so that they occlude with the lower teeth U pper p a latal cusp ...........؟؟؟............ ( lingualized occlusion ) A combination of lever balance and occlusal balance is possible by incorporating both a buccal tilt and a lingual tilt in the posterior arrangement.

98. If the upper arch is much wider than lower arch : - Set the lower first on the ridge - Set the upper and lower separately

99. - lingualized occlusion Occlusal scheme - Monoplane occlusion

100. Problems and possible solutions For Class III arch relationship

101. Problem >> Concave face profile with prominent mandible is associated with Class III malocclusion . A ngle class III

102. Problems associated with class III cases The relation between the ridges may vary from edge to edge relationship to extreme prognathism of the lower arch. Wider lower arch leads to problems in selecting the size of the teeth as selecting the same mold size for both arches leads to spacing between lower anterior teeth which reduce aesthetics. The Crest of the lower arch is located further buccally than that of the upper one, leading to problems in obtaining an adequate occlusal relation between upper and lower teeth.

103. Anterior teeth arrangement: Edge to edge relationship Inclining the mandibular anteriors lingually as possible without encroaching the tongue space. Modifications Done In Setting Up of Teeth for Angle Class III Inclimig the maxillary anteriors more anterior to the crest of the ridge than usual, with their incisal edges being inclined more labial than their necks

104. Slight crowding of upper anteriors Addition of lower lateral or central incisor Wider lower anteriors Slight crowding in upper anteriors

105. Posterior teeth arrangement: Monoplane posterior teeth or cuspless teeth ( preferred ) Upper posterior teeth can be placed slightly buccal to the crest of the upper ridge. Cross-bite is accomplished to avoid unfavorable leverage that compromises denture stability Larger sized upper posteriors + Medium sized lower posteriors In case of wider lower arch, an interchange can be done by using upper teeth on the lower denture and lower teeth on the upper denture.

106. Lingualized articulation “an occlusion for all reasons” There is hardly a clinical situation where it is not applicable and the adjustments, especially at the chairside, This scheme use cusped upper teeth 30_ or 33_ cuspal angles, modified to ensure that the buccal cusps take no part in the articulation. The lower teeth use 20_ or 0_ teeth, Occlusal surfaces are in harmony with the angles of the upper palatal cusps, as well as the Refers to the inner maxillary cusps as palatal cusps, for obvious reasons. The main problem with posterior tooth placement in these cases, is that of a medio -lateral arch discrepancy and the need for a cross-bite arrangement. In this case, the lingualized concept becomes a “ buccalized ” one

107. 2. Modifications Done In Posterior Teeth Morphology: SR Orthotyp Teeth It was Designed by Dr. R Strack in the 1950’s and manufactured by Ivoclar Vivadent . His morphology recognizes the three bite classifications: Class I (normal bite –N mould ) Class II (deep bite- T mould ) and Class III (cross bite – K mould ). They differ in the cusp angulations and the guiding surfaces.

108. Failure to make the canine the turning point of the arch Setting mandibular 1st premolar to the buccal side of the canines. Setting the mandibular posterior teeth too far to the lingual side in the 2nd molar region which cause tongue interference and mandibular denture displacement Failure to establish the occlusal plane at the proper level and inclination Establishing the occlusal plane by an arbitrary line on the face Common errors in arrangement of teeth

109. Buccal Corridor Space between buccal Surface of posterior teeth and inner surface of cheeks. Excessive Buccal Corridor results when posterior teeth are set too far lingually. Resulting dark space appears excessive and unaesthetic. Inadequate Buccal Corridor occurs when posterior teeth are set too far buccally, causing obliteration of the buccal corridor .

110. Conclusion: Generally monoplane teeth are more adaptable for unusual jaw relationships and permits the use of a simplified and less time consuming technique Lingualised articulation is also recommended for the majority of cases where it can easily solve most difficulties provided the principles of balanced articulation .

111. Mother Tereza

112. References Kaddah A, and Libshtien IA.: Occlusion in Prosthodontics: Varieties, aberrations and managements. 1988 Applebaum M. (1984): Plans of occlusion. In: Dental Clinics of North America: Becker C.M., Swoope C.C. and Guckes A.d. (1977): Lingualized occlusion for removable prosthodontics. Journal of Prosthetic Dentistry 38:601-608. Krishna Prasad D. et al. “Enhancing Stability : A Review of Various Occlusal Schemes in Complete Denture Prosthesis” NUJHS Vol. 3, No.2, June 2013, ISSN 2249-7110 Symposium on removable prosthodontics. Pp 273-285. W.B.Saunders , Philadelphia. Ivoclar vivadent company  

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