ANDREWS STRAIGHT WIRE APPLIANCE 1 and 2.pptx

ANDREWS STRAIGHT WIRE APPLIANCE

1. ANDREWS STRAIGHT WIRE APPLIANCE Presented by Dr. Roshni Krishnan Post Graduate Student Second Year

2. Content (Part – 1) Introduction History Naturally occurring optimal occlusion Six keys to optimal occlusion Measurements Normality, abnormality, optimally Non programmed appliance 2

3. Content (Part – 2) Fully programmed standard brackets Fully programmed translation brackets Partially programmed appliances Andrews 2 appliance Conclusion References 3

4. Introduction

5. Regardless of one’s expertise in other aspects of orthodontics, fitting the teeth together as well as they can be is essential to being a good orthodontist. Bracket stand between the teeth and the orthodontist, which one are prescribed play a large role in the quality of the results and in treatment efficiency. One must ask in matters of occlusion, whether there are clinical limitations that prevents orthodontists from reaching goals considered exemplary by others. 5

6. Initial attempt to assess the state of the art of orthodontics in terms of post treatment static occlusion did not yield the consistent and adequate data required for firm conclusions. One implication, however was clear the paragon positions of natural teeth could be found only by studying dentitions with naturally optimal occlusion. 6

7. History

8. Dr. Lawrence Fredrick Andrews Research spanning ten years led to the Six Keys to Optimal Occlusion , quantifying the tooth positions of naturally optimal dentitions, and the Andrews Straight-Wire Appliance. 8

9. 1962 1965 1965 1965 1970 1989 9

10. NATURALLY OCCURING OPTIMAL OCCLUSION

11. On the hypothesis of naturally occurring optimal occlusion would be worthy of emulation, casts of such dentitions were collected over a period of 4 year. Fifteen orthodontists and general dentists assisted in this research among which Dr. A . G Brodie arranged to duplicate a collection of casts with naturally good to excellent occlusion at the university of Illinois orthodontic department. 11

12. By 1984 the sample comprised 120 casts. These samples comprised of dentitions: Have never been subjected to orthodontic treatment Are well aligned and pleasing in appearance Appear to have excellent occlusion 12

13. Six keys to optimal occlusion

14. The most important step leading to the development of the appliance was the discovery of six characteristics that were consistently present in the collection of 120 casts of naturally occurring optimal occlusion. These qualities are referred to as “ Six Keys to Optimal Occlusion ”. 14

15. They have special value for the orthodontist because Complete set of indicators of optimal occlusion Can be judged from tangible landmarks Can be judged from facial and occlusal surfaces of crowns reducing the need for a lingual view or for articulating paper to confirm the occlusal interface. 15

16. Andrews plane: The surface or plane on which the mid-transverse plane of every crown in an arch will fall when the teeth are optimally positioned. 16

17. Clinical crown: Normally the amount of crown that can be seen intraorally or with a study cast. 17

18. Crown angulation: The angle formed by the facial axis of the clinical crown and a line perpendicular to the occlusal plane. 18

19. CROWN INCLINATION Angle between a line perpendicular to the occlusal plane and a line that is parallel and tangent to the FACC at its mid-point ( FA point ). 19

20. Facial Axis Of The Clinical Crown: For all teeth except molars, the most prominent portion of the central lobe on each crown’s facial surface while for molars the buccal groove that separates the two large facial cusps. 20

21. Facial Axis Point (FA point) : The point on the facial axis that separates the gingival half of the clinical crown from the occlusal half. 21

22. Mid sagittal plane An imaginary line that separates the crown mesio - distally at the facial axis of the clinical crown (FACC). Mid transverse plane An imaginary line that separates occlusal half the crown from the gingival half of the crown. 22

23. Key I : Interarch Relationship Pertains to the occlusion and the Interarch relationships of the teeth. 23

24. This key consists of seven parts: The mesiobuccal cusp of the permanent maxillary first molar occludes in the groove between the mesial and middle buccal cusps of the permanent mandibular first molar. The distal marginal ridge of the maxillary first molar occludes with the mesial marginal ridge of the mandibular second molar. 24

25. 3. The mesiolingual cusp of the maxillary first molar occludes in the central fossa of the mandibular first molar. 4. The buccal cusps of the maxillary premolars have a cusp – embrasure relationship with the mandibular premolars. 5. The lingual cusps of the maxillary premolars have a cusp – fossa relationship with the mandibular premolars. 25

26. 6. The maxillary canine has a cusp – embrasure relationship with the mandibular canine and first premolar. The tip of its cusp is slightly mesial to the embrasure. 7. The maxillary incisors overlap the mandibular incisors and the midlines of the arches match. 26

27. Molar relationship: When Angle described about molar relationship he stated that the mesiobuccal cusp of the upper first permanent molar should rest on mesiobuccal groove of the lower first permanent molar. But non orthodontic models consistently demonstrated that “ Distal surface of the distobuccal cusp of the upper first molar occluded with the mesial surface of the mesiobuccal cusp of the lower second molar ” 27

28. 28

29. Key II : Crown Angulation Essentially all crowns in the sample have a positive angulation. All crowns of each tooth type are similar in the amount of angulation. 29

30. Key III : Crown Inclination Most maxillary incisors have a positive inclination ; the centrals have more positive than the laterals. Canines and premolars are negative and quite similar. Molars are slightly negative but slightly more negative than canine and premolars. M andibular incisors have slightly negative inclination and are progressively more negative from the incisors through the second molars. 30

31. Key IV : Rotations The fourth key to optimal occlusion is an absence of tooth rotations. 31

32. Key V : Tight Contacts Contact points should abut unless a discrepancy exists in mesiodistal crown diameter. 32

33. Key VI : Curve Of Spee The depth of the curve of spee ranges from a flat plane to a slightly concave surface. 33

34. Key VII : Tooth size In 1993 Bennet and McLaughlin gave 7 th key of normal occlusion ; the tooth size of upper and lower arch should be correctly balanced. If not, there would be either spacing in one arch or crowding in opposing arch. Tooth size is actually the 7 th key of normal occlusion. Andrew’s non orthodontic normal models had balanced tooth size. John C. Benenett , Richard P. McLaughlin. Orthodontic management of the dentition with the Pre-adjusted appliance. 1997;1:1-24 34

35. Measurements

36. The fourth study leading to the development of the first fully programmed appliance involved thousands of measurements of the crowns in the 120 cast sample. The purpose was to learn the extent to which position and shape were constant within each tooth type and how relative size was consistent within an arch. 36

37. The measurements made were : Bracket area of each tooth type Vertical crown contour Crown angulation Crown inclination 37

38. 5. Maxillary molar offset 6. Horizontal crown contour 7. Facial prominence of each crown 8. Depth of curve of spee 38

39. The facial axis of the clinical crown (FACC) and the facial axis point (FA Point) were marked on the each crown of the dental casts. The FACC is the reference line from which crown angulation and inclination are measured. 39

40. Duplicate casts of 120 casts were made and the occlusal half of each crown was trimmed away. A line was drawn on the trimmed surfaces of the casts, connecting the most facial aspects of the contact areas. This is called as the “ embrasure line” . 40

41. The maxillary molar offset and the most facially prominent portion of each crown were measured from embrasure line. Ultimately these data were used in bracket design to eliminate the need for first order arch wire bends. 41

42. Bracket area: The smallest crowns of each normal tooth type determined the occlusogingival height and mesiodistal width limits of each bracket base 42

43. Vertical Crown Contour 43

44. Crown Angulation 44

45. Crown Inclination 45

46. Offset of Maxillary Molars 46

47. Horizontal Crown Contour 47

48. Crown Facial Prominence 48

49. Depth Of Curve Of Spee 49

50. Findings of the experiment Crown inclination: ( Torque ) 7 3 -7 -7 -7 -9 -9 U1 U2 U3 U4 U5 U6 U7 L1 L2 L3 L4 L5 L6 L7 -1 -1 -11 -17 -22 -30 -35 50

51. Findings of the experiment Crown Angulation: ( Tip ) 5 9 11 2 2 5 5 U1 U2 U3 U4 U5 U6 U7 L1 L2 L3 L4 L5 L6 L7 2 2 5 2 2 2 2 51

52. Findings of the experiment Crown Prominence : 52

53. Findings of the experiment Offset of Maxillary Molars : Maxillary molar offset averaged 10 relative to the embrasure line while no offset is needed for mandibular molars because the middle and mesiobuccal cusps are equally prominent. Curve of Spee : Ranged from flat to 2.5 mm deep 53

54. Normality , Abnormality, Optimally

55. Abnormality : Individuals with abnormal jaws and teeth. Eg – cleft palate, peg laterals etc. treatment for this group always needs a multi disciplinary approach Naturally optimal : Group with normal teeth and jaws who require no orthodontic treatment. 120 non orthodontic models can be included in this group. Normal malocclusion : Group with malocclusion which can be treated to optimal standards. 55

56. Both the naturally optimal and the normal malocclusion fall under a same category where they are differentiated only through 6 keys of occlusion. It seemed feasible to design an appliance that could be readily applied to normal teeth with normal malocclusions and direct them to optimal goals. When correctly sited the brackets would be designed to provide the guidance needed with few wire bends. The development of this appliance resulted partly from the 6 keys of optimal occlusion and partly from detailed analysis of limitations of edgewise appliance. 56

57. The Non Programmed Appliance

58. Slot Stem Slot base Tie wings Base point Bracket base Slot point Tie wings 58

59. Non programmed appliance : A set of brackets designed the same type for all tooth types relying totally on wire bending to achieve the optimal position for each individual tooth. Partly programmed appliance : A set of brackets designed with some built in features but that always requires some wire bending 59

60. The Angle designed edgewise brackets are “non programmed” because of their bilaterally symmetrical design. Angle recognized some consistencies in the position of optimally occluded teeth, as shown in his directive to complete active treatment with an ideal archwire. However Angle did not incorporate these treatment objectives into his appliance. 60

61. Design shortcomings: For tooth movement not involving translation, six factors cause the slot of non programmed edgewise brackets to be sited in ways that always require archwire bends. Perpendicular bases Bases not contoured occlusogingivally Mesiodistal base contour Slots not angulated Stems of equal prominence Maxillary molar offset not built-in 61

62. Perpendicular bases: The base of the non programmed bracket is perpendicular to the stem. This feature can cause problems f or the slot inclination and occluso gingival position. 62

63. Each crown in an arch has its own optimal amount of inclination. Therefore brackets having bases that are perpendicular to their stem and sites base point of each crown will target their slots so that many different inclination and occlusogingival levels, even when the base point of the bracket is sited on the FA point of the crowns occlusogingivally the slots are poorly aligned to the Andrew’s plane. 63

64. 64

65. 2. Bases not contoured occlusogingivally Occlusogingivally the bracket is flat but the facial surface of crown is curved. So when such a bracket is being attached to the crown it can unintentionally be rocked occlusally or gingivally. 65

66. There will be irregular slot sitting in each of the arch caused by vertically flat based brackets. Only a part of the bracket will be touching the crown. 66

67. 3. Mesiodistal base contour Irregular mesiodistal slot sitting can occur when the mesiodistal contour of the bracket base does not match that of the crown. 67

68. 4. Slots not angulated : The bracket slots of the edgewise brackets are non angulated. 68

69. When the vertical components of the brackets are sited parallel to FACC and base point sited at FA point the angle of the slot vary to many different angulation. Under these circumstances , the inclination and occlusogingival ranges for slot sitting are greater than when the bracket is not angulated. 69

70. 5. Stem of equal prominence: Distance between bracket base and center of slot is same in each brackets. 70

71. Therefore when the brackets are placed they become as irregular in the facial prominence as the crown. So when the unbent archwire the facial surface of the each crown becomes equidistant from the embrasure line, which is undesirable. 71

72. 6. Maxillary offset not built – in: Since the maxillary molars offset is not built in, the mid sagittal plane of the slot is angular to the mid sagittal plane of the crown. This will lead to rotational effect of molars. So a first order bend must be installed into archwire to accommodate these differences. 72

73. Non programmed brackets are simple in design, easily manufactured and inexpensive but difficult to use because considerable wire bending is needed throughout the treatment. There are three type of wire bending: Primary wire bending Secondary wire bending Tertiary wire bending 73

74. Primary wire bending: Intended for the most direct movement of the teeth. Consists of : First order bend Second order bend Third order bend 74

75. First order bend 75

76. b) Second order bend 76

77. c) Third order bend 77

78. When the brackets are sited on a full complement of optimally positioned teeth, the final “ideal” archwire will require 76 primary wire bending if it is to be places passively into the slots. This number includes 46 bends for angulation, inclination and offset and 30 bends for prominence and occlusogingival slot position error.. 78

79. 2. Secondar y wire bending: Any bends which are for tooth guidance and that are not primary bends Secondary bends are needed to compensate for slot sitting irregularities caused by bracket design and unreliable bracket sitting techniques, wire bending and wire forming side effects. 79

80. 3. Tertiary wire bending: Any bends that are placed for any reason other than guidance. Eg – omega loops for stops, loops for increasing wire flexibility and loops for elastics. 80

81. ANDREWS STRAIGHT WIRE APPLIANCE Presented by Dr. Roshni Krishnan Post Graduate Student Second Year

82. PART - II

83. Fully programmed appliance

84. 84 The concept of programming tooth guidance into bracket rather than into wire is based on the recognition that extensive similarities prevail morphology of normal tooth types and their positions when they are optimally occluded. A fully programmed appliance puts these similarities to work, accomplishing all or nearly all tooth guidance with flexed but unbent archwires. Fully programmed standard brackets Fully programmed translation brackets

85. Fully programmed standard brackets

86. 86 The simplest version of fully programmed appliance consists of standard brackets designed to guide teeth that do not require translation. There is one standard bracket for each tooth type except for incisors and maxillary molars; for incisors there are three while for maxillary molars two. To eliminate archwire bending, more slot siting features are required than just the correct amount of slot angulation, inclination and facial prominence.

87. 87 Auxiliary feature: A design feature that contributes to the biological aspect of treatment but is not involved in targeting the slot. Convinence feature: A design feature that facilitates use by the orthodontist or promotes comfort for the patient but does not contribute to the biological aspects of treatment or to targeting the slot. Fully programmed appliance: A set of brackets designed to guide teeth directly to their goal positions with unbent archwires.

88. 88 Inclined base: A bracket base that is angled more or less than 90 to the midtransverse plane of the bracket stem. Inclined slot: A slot whose midtransverse plane is inclined relative to the midtransverse plane of the bracket stem. Maxillary molar offset: the angle between the crown’s embrasure line and a line connecting the buccal cusps of a maxillary molar. It is measured along the crown’s midtransverse plane.

89. 89 Mesiodistal base contour: the horizontal contour of the brackets base. Occlusogingival base contour: The vertical contour of the bracket base.

90. 90 Slot point Slot point: The junction of the midtransverse, midsagittal and midfrontal planes of the bracket slot. Slot site: The area that the bracket slot must occupy if it is to passively receive a fully size unbent archwire when a tooth is optimally positioned. Slot area

91. 91 Standard bracket: A fully programmed bracket designed for teeth that do not require translation.

92. 92 Translation bracket: A fully programmed bracket for teeth that require translation. It is designed to promote bodily movement during mesial or distal movement.

93. 93 Mid transverse plane :- Feature 1: The midtransverse planes of the slot, stem and crown must be the same.

94. 94 Mid transverse plane :- Feature 2: The base of the bracket for each tooth type must have the same inclination as the facial plane of the crown at the FA point.

95. 95 Mid transverse plane :- Feature 3: Each bracket’s inclined base must be contour occlusogingivally to match the curvature of the crown.

96. 96 Mid transverse plane :-

97. 97 Mid sagittal plane :- Feature 4: The midsagittal plane of the slot, stem and crown must be the same.

98. 98 Mid sagittal plane :- Feature 5: The plane of the bracket base at its base point must be identical to the facial plane of the crown at the FA point.

99. 99 Mid sagittal plane :- Feature 6: The base of each bracket must be contoured to the match the mesiodistal radius of the area of the crown it is designed to fit.

100. 100 Mid sagittal plane :- Feature 7: In each fully programmed bracket, the vertical components are designed to parallel one another. These components, when the parallel and midpoint bracket siting technique is used. The horizontal components of the bracket are the superior and inferior sides of the bracket stem.

101. 101 Mid sagittal plane and mid transverse plane :- Eliminates requirement of first order bends. Eliminates requirement of second order bends for angulation Occlusogingival slot siting

102. 102 Mid frontal plane :- Feature 8: Within an arch, all slot points must have the same distance between them and the embrasure’s line. It eliminates first order wire bends to accommodate for varying crown prominence.

103. 103 Convenience features: It do not play a role in slot siting, but they make the appliance easier for the orthodontist to use and sometimes more comfortable for patient.

104. 104

105. Fully programmed translation brackets

106. 106 A fully programmed appliance must offer more than one standard or basic version. When teeth require bodily movement, translation brackets have significant advantages over standard brackets. Translation brackets have all the qualities of standard brackets plus a power arm and two additional slot siting features ‘counter – mesio distal tip’ and ‘counter rotation’. Maxillary molar brackets include a third feature ‘counter buccolingual tip’

107. 107 These features along with the archwire and mesial or distal force, provide counter moments for translation and the guidance needed for overcorrection in all three planes of space.

108. 108 Counter buccolingual tip: A slot siting feature for maxillary molars that counteracts buccolingual tip during translation and then overcorrects. Counter mesiodistal tip: A slot siting feature that counteracts mesial or distal tipping during translation and then overcorrects. Counterrotation: A slot siting feature that counteracts rotation during translation and then overcorrects.

109. 109

110. 110 Maximum translation bracket: A translation bracket for posterior teeth that require more than 4mm of translation. Medium translation bracket: A translation bracket for teeth that require more than 2 mm but not more than 4mm of translation. Minimum translation bracket: A translation bracket for teeth that require 2 mm or less of translation.

111. 111 Counterrotation:

112. 112 Counterrotation:

113. 113 Counterrotation: Slot rotation + mesiodistal slot length + archwire flex + mesial or distal force

114. 114 Counter mesiodistal tip:

115. 115 Counter mesiodista l tip:

116. 116 Counter buccolingual tip:

117. Part ly programmed brackets

118. 118 By definition, a partly programmed appliance lacks at least one slot siting feature for this reason alone it would fail to fully direct each slot to its tooth’s slot site In actuality the inadequacy in both quality and quantity of slot siting feature makes wire bending necessary.

119. 119 Its brackets have four slot siting features : Slot inclination, Slot angulation , prominence and horizontal base curvature. This is in contrast to the non programmed appliance which has none and fully programmed appliance which has eight for standard brackets and eleven for translation brackets.

120. 120 Slot inclination: The amount of slot inclination for each bracket is the same as the base inclination for each fully programmed standard bracket. Non programmed brackets have no inclination while in fully programmed brackets the inclination is built in base.

121. 121 Slot inclination:

122. 122 Slot angulation:

123. 123 Slot prominence: Eliminates the need of first order bends. Several data indicated faciolingual prominence as thinner or thicker than in non programmed brackets An amount of more than 0.5 mm from the amount in Straight wire appliance can be considered clinically significant.

124. 124 Horizontal base contour: Most partly programmed and some non programmed brackets have horizontal base contour. They may or may not be same as for the straight wire appliance.

125. 125 If they are not, an appliance will not be reliably locate the mid sagittal plane of the bracket stem and slot on the crown’s mid sagittal plane.

126. 126 Patent restrict translation slot siting features; that means unless treated with combinations of wire bending and possibly with auxiliary rotation devices, none of the teeth requiring translation will translate.

127. Andrews 2 Appliance

128. 128 The Andrews 2 Appliance is comprised of both standard and translation brackets. Teeth that do not require translation are assigned standard brackets. Teeth that need to be translated mesially or distally are assigned translation brackets – minimum (T1), medium (T2), or maximum (T3) depending on the distance the teeth need to be translated. Andrews 2 Brackets can be prescribed individually or by prearranged set.

129. 129 There are 11 sets for the maxillary arch and 10 for the mandibular arch. Arch correction efficiency is maximized when the most appropriate brackets are prescribed, properly sited, and the most suitable archwires and forces are applied. When used as such it becomes a fully-programmed appliance.

130. 130

131. 131

132. 132 The bracket sets are combinations of 5 different types of brackets S – Standard bracket T1 – Minimum translation bracket T2 – Medium translation bracket T3 – Maximum translation bracket T4 – Maxillary molar 7mm overjet bracket

133. Conclusion

134. 134 The SWA is programmed to deliver treatment to optimum end results with few archwire bends. This is possible, basically, because of the commonality of dental morphology in our species. Andrew stressed on translation of the teeth utilizing sliding mechanics with different series of brackets for extraction and non extraction cases. But the problem of extensive inventory of brackets was a setback to Andrews’s prescription.

135. References

136. 136 1. Andrews LF. The Six Keys to Normal Occlusion. American Journal of Orthodontics, 1972;62:296-309. 2. Andrews LF. The straight wire appliance origin, controversy, commentary. J Clin Orthod . 1976;10(2):99– 114. 3. Andrews LF. The straight wire appliance explained and compared. J Clin Orthod . 1976;10(3):174–195. 4. Andrews LF. JCO interviews on the straight-wire appliance. J Clin Orthod . 1990;24:493-508.

137. 137 5. Andrews LF. The straight-wire appliance. Extraction series brackets. J Clin Orthod . 1976;10(6):425-441. 6. Andrews LF. The straight-wire appliance. Extraction series brackets. J Clin Orthod . 1976;10(7):507-529. 7. Andrews LF. Straight Wire: The Concept and the Appliance. 1989, San Diego, L A Wells Co. 8. Andrews LF. Fully programmed translation brackets. In: Andrews LF, ed. Straight wire: the concept and appliance. San Diego, CA: LA Wells;1989.

138. THANK YOU