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Building treatment mechanics through brackets /certified fixed orthodontic courses by Indian dental academy


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Building treatment mechanics through brackets /certified fixed orthodontic courses by Indian dental academy

  2. 2. P r e s e n t e d I. Introduction II. Various appliance system discussed 1. ALEXANDER DISCIPLINE. 2. ROTH.(Few variations suggested by b y G a n e s h I. Various gauges used in bracket R a o Bennet and mclaghlin) 3. M.B.T. 4. LINGUAL APPLIANCE. 5. BEGG APPLIANCE. positioning. II. Common errors in bracket positioning. III.Special considerations in bracket positioning. IV.Conclusion.
  3. 3. Introduction: In the past, the best results were achieved by orthodontists who were the the best wire benders. The emphasis has changed since the development of the pre-adjusted appliance by Andrews. The best results in the future will be achieved by those orthodontists who are best at accurate bracket positioning.
  4. 4. Orthodontic treatment is based upon specific force applications to the dentition, the maxilla and the mandible. In order to obtain these forces in a fixed appliance, orthodontic brackets are attached to the teeth.
  5. 5. The brackets themselves produce no force. They are merely handles for attachment of the force producing agents. However, brackets can effect the directions of the force vectors when torque, angulations, and in/out are built in to the brackets.
  6. 6. Andrews measured 120 non orthodontic normal models to establish the TIP, TORQUE and IN/OUT measurements built in to the pre-adjusted appliance . He found that millimeter measurement system for bracket positioning as used with standard edgewise, was not satisfactory for the pre-adjusted appliance.
  7. 7. Using that system for both large and small teeth would not provide a consistent reference point for expression of the three dimensional forces on each tooth. For example, a bracket placed 5mm from the incisal edge of an upper central incisor would be located at a different position on the crown for large versus small teeth. This in turn would create a small difference in the torque position and the thickness position of the tooth.
  8. 8. Andrews therefore rightly chose the centre of clinical crown as a horizontal reference point, so that the expression of TORQUE and IN/OUT compensation would be consistent for both large and small teeth.
  9. 9. Andrews used the long axis of the clinical crown a vertical reference, which was the center of the middle developmental lobe of the crowns from central incisor to second bicuspid, and buccal grove of the first and second molar crowns.
  10. 10. FIVE FACTORS WHICH DEFINE ANY BRACKET SYSTEM: 1. Bracket Type. 2. Placement Positions. 3. Angulations. 4. Torque. 5. In/Outs.
  11. 11. Following are the some Appliance systems which have incorporated bracket positioning variations in order to achieve better treatment outcomes. 1. ALEXANDER DISCIPLINE. 2. ROTH. 3. M.B.T. 4. LINGUAL APPLIANCE. 5. BEGG APPLIANCE.
  12. 12. 1. ALEXANDER DISCIPLINE. The Concept of the Vari Simplex Discipline The system evolved around five factors related to brackets:  Bracket selection,  Bracket height,  Bracket angulations,  Bracket torque,  Bracket in-out.
  13. 13.  Bracket selection Each tooth has a particular bracket that is most effective. Twin Brackets (Diamond brackets) Are used on large, flat-surfaced teeth— maxillary central and lateral incisors. The Diamond bracket is designed so that all the horizontal lines are placed parallel to the incisal edge of the tooth, and the rhomboid design makes it possible to align the vertical lines parallel to of the tooth. the long axis
  14. 14. The flat surfaces of maxillary centrals and laterals permit full archwire engagement in the twin brackets. The accessibility of these teeth negates the usual difficulty in tying twin brackets. Also, twin brackets on the incisors allow 5-6mm of inter-bracket width, which is sufficient for flexibility, rotational control, and torquing ability.
  15. 15. Lang Brackets Lang brackets were invented by Dr. Howard Lang. Brackets with Diamond design are placed on large, round-surfaced teeth at the corners of the arch such as maxillary and mandibular cuspids Lang bracket. A. When a Lewis or Steiner bracket is completely tied into a cuspid, there is a tendency to flatten the curvature of the archwire. B. A Lang bracket avoids this effect, while retaining the A rotation wing capability. B
  16. 16. Lewis Brackets It is prefered to use Lewis brackets on large, round-surfaced teeth that are not at the curve of the arch such as maxillary and mandibular bicuspids and on small, flat-surfaced teeth such as mandibular incisors.Using the basic Lewis design with a wedge shape, which puts the tie wing close to the tooth occlusally and far out gingivally. This makes it easy to tie, to use as a hook for elastics, and to keep clean.
  17. 17. Removing the interfering wing of Lewis bracket on badly rotated tooth permits proper bracket placement.
  18. 18. Other Attachments Twin brackets with a convertible sheath are used on maxillary and mandibular first molars, which are usually banded. The convertible sheath is easily removed when second molars are banded, converting the attachment to a bracket.
  19. 19. Headgear tubes are placed occlusally on the maxillary first molars.This position makes it easier to see and to use them; it minimizes food traps, oral hygiene problems, and gingival impingement; and it eliminates blockage when omega stops are used. Twin bracket with convertible sheath on molar.
  20. 20. Bicuspid bracket height is the key (X on the chart below) because its clinical crown height is so variable. Its normal height is 4.5mm. The other bracket heights are calculated in relation to X, as shown on the chart. Maxillary Arch Centrals X Laterals X – 0.5mm Cuspids X + 0.5mm Bicuspids X 1st Molars X – 0.5mm 2nd Molars X – 1.0mm Mandibular Arch Centrals X – 0.5mm Laterals X – 0.5mm Cuspids X + 0.5mm Bicuspids X 1st Molars X – 0.5mm
  21. 21. Bracket Height Placing a bracket higher or lower affects the amount of torque and angulations, and the incisogingival position of the tooth. Obviously, bracket height will vary to fit the clinical crowns. Cusp tips vary, and that is a consideration. If incisors have chipped edges or mam-melons, the teeth should be recontoured or the bracket height adjusted before bracket placement.
  22. 22. An obvious deviation from these measurements would be in an open bite case. Since the treatment plan would be to intrude the posterior teeth and extrude the anterior teeth , increase the bracket height on anterior teeth by 0.5mm and decrease the bracket height on posterior teeth by 0.5mm.
  23. 23. When banding bicuspids in extraction cases, the band is seated more gingivally on the side toward the extraction site, Hence it is not necessary to angulate the bracket. This provides adequate tip of the bicuspid root into the extraction site, which, combined with the 6° tip in the cuspid, is sufficient to parallel the roots.
  24. 24. The mandibular first molars have a 6° tipback built in to promote leveling and to gain arch length. There is 0° angulation on the mandibular second molars, since these teeth rarely need to be uprighted excessively. If necessary, they can be uprighted by placing a tipback bend in the archwire when bending the omega stop.
  26. 26. 2.ROTH  Roth in 1975 evaluated the preadjusted bracket system after he had it for 5 years. used  In 1981 he modified the appliance by altering the amount of pre-adjustment built into the brackets.  His objectives were to have the teeth in overcorrected positions at the end of treatment when unbent, full-sized wires were used.
  27. 27. Some slight variations in bracket placement are recommended for the Roth set up; thus a flat unbent rectangular, full sized wire can be used as a finishing wire rather than one with reverse and compensating curves.
  28. 28. The key in determining bracket height is the canines and premolars(second premolars in extraction case). Ideally the center of brackets should be placed at the maximum convexity of the crowns of the posterior teeth. (i.e center of clinical crown-LA point. )
  29. 29. Sometimes it is necessary to place the brackets of the anterior teeth more incisally in order to achieve the leveling of the curve of spee. A good guide is to make the tip of each canine 1mm longer than that of the adjacent lateral incisors. In addition the maxillary central incisors should be bracketed to be equal in height to the maxillary laterals.
  30. 30. Individual bracket placement variations: Maxillary first molar bands. As the band is being seated, keep the slot horizontal and level in relation to the crown. The buccal cusps can be used as a guide. Since the band will tend to be seated more on the distal, 0o of tip is incorporated in the tube to avoid distal root tip.
  31. 31. Maxillary second molar bands: It is better to seat the band slightly more occlusal. This will help avoid a posterior interference or fulcrum.
  32. 32. Mandibular first molar bands: Using the band as a guide, keep the slot approximately horizontal and level in relation to the crown. The buccal cusps can be used as a guide, since a slight over correction of –3o is incorporated in the tube to prevent excessive mesial crown tip.
  33. 33. Mandibular second molar bands: It is better to seat the band slightly more gingival . Initially, if the slot is too occlusal, the mandibular second molars tend to roll in lingually when a significant intrusive force is applied.
  34. 34. Mandibular second and first premolar bonds: Center the bracket mesiodistally on the prominent buccal developmental ridge and centre the slot with the maximum convexity of the crown.
  35. 35. Mandibular canine bonds: From the occlusal, center the bracket mesiodistally on the prominent buccal developmental ridge. Align the center of the slot with the widest part of the canine (mesiodistally). This point will vary depending on the size of the other teeth and the size and shape of the canine and it’s tip. The cusp tip is 0.5 to 1mm higher occlusally than the rest of the occlusal plane.
  36. 36. Mandibular incisor bonds: Position the center of the slot so that the incisal edge of each incisor is 0.5 to 1mm shorter gingivally than the canine tip. The lower six anterior brackets should be slightly more incisal relative to the L.A point, which will allow the leveling of the curve of spee.
  37. 37. Maxillary second and first premolar bonds: Align the center of the slot with maximum convexity(Mesiodistally) of the crown.This corresponds to the center(occlusogingivally) of a fully erupted normal sized premolar.
  38. 38. Maxillary second and first premolar bonds: The most common error is not placing the brackets gingival enough. Bennet and Mclaughlin recommend to place the upper first bicuspid bracket 0.5mm gingival to the center of the clinical crown.
  39. 39. Evaluation of treated cases revealed that the center of the clinical crown of the upper first and second bicuspids was 0.5 mm occlusal to a line connecting other clinical crown centers.
  40. 40. Maxillary canine bonds: Align the center of the slot approximately along the widest part of the canine mesiodistally. Then make adjustment to the height . The cusp tip is 1 to 1.5 mm higher incisally than the rest of the occlusal plane. Position the bracket slightly more incisally relative to the L.A point or center of the normal fully erupted crown.
  41. 41. Maxillary lateral bonds: Center of the slot should be in the middle of the crown (mesiodistally). With the small laterals the incisal edge will align on the base of the bracket. This will effectively give the lateral more distal root tip, thus allowing a small lateral to take up more space in the arch.
  42. 42. The incisal edges of the maxillary laterals and centrals should be on the same level. This is 1 to 1.5mm shorter than the maxillary canine tip.
  43. 43. Maxillary central bonds: The distance from slot to the incisal edge should be the same as for the maxillary laterals. The slightly more incisal positioning of these brackets will allow treating to a level curve of spee with a flat archwire rather than placing reverse and compensating finishing curves.
  44. 44. In Situations requiring only maxillary premolar extractions,maxillary first and second molar tubes with 0o antirotation are used , which will allow the maxillary molar to take up more space in the arch and provide a better fitting class II posterior occlusion.
  45. 45. In cases requiring the super torque maxillary incisor brackets, use a canine bracket with slightly more (+3)torque. This compensation will prevent excess labial root torque to the maxillary canine.
  47. 47. If it is intended to treat to a class II molar result (For example , following loss of two upper premolars and no lower premolar extractions), then better occlusion can be obtained if upper first and second molars are allowed to rotate mesially. Occlusal adjustment may be required at the end of the treatment to ensure good lateral excursions.
  48. 48. These tubes have zero distal rotation compared 10o in normal prescription. They are helpful when treating to a class II molar result
  49. 49. Placement of different canine brackets on narrow Maxillary or Mandibular bone. Some patients often has narrow arches, with upper and lower canines blocked out buccally. Canine brackets with –7o upper torque and –11o lower torque are not helpful in correcting such problems Canine brackets with zero torque encourage canine roots to lie more in cancellous bone allowing easier retraction.
  50. 50. Missing upper lateral incisors: If lateral incisor is missing and it has been decided to close the space, good torque control of upper canine is needed, and to change the torque from –7o to +7o the bracket is inverted 180o. This opposite torque helps to move the canine roots palatally
  51. 51. Instanding upper lateral incisors These teeth have special torque needs during finishing and detailing. It may be helpful to place a bracket rotated through 180o to give –10o torque
  52. 52. Axial/paralleling variations: In treating cases where an anterior tooth has been extracted(or missing), it is helpful to vary the axial position when bonding teeth adjacent to extraction site. This assists in achieving root paralleling and reduces the amount of wire bending required during treatment.
  53. 53. Over correction of Axial rotation correction can be achieved by offsetting the brackets mesially or distally. A J O 1 9 9 3 Interaction of bracket control rotations. and arch wire to S e p
  54. 54. Upper first molar bracket positioning The vertical placement is decided using the Bracket placement chart. It is a common error to allow the band to seat too gingivally at the distal,causing excessive crown tip.
  55. 55. Upper first molar bracket positioning Correct positioning Mesio-distally the bracket should straddle the buccal grove. Band seated more gingivally when treating to a class II molar relationship.
  57. 57. Upper second molar In all cases upper second molar brackets are placed 2mm from the occlusal surface of the crown
  58. 58. Lower second molar If the second molar tube is placed too occlusally, a marginal ridge discrepancy occurs. It is a common error to allow first and second molar bands to seat too gingivally on the mesial aspect. This causes tipping and marginal ridge errors. The second molar tube should straddle the buccal grove of the lower molar
  59. 59. 3.MBT MBT Appliance system emphasizes on its versatility and bracket positioning.
  60. 60. Design features: Like other modern bracket systems , MBT system also have been developed using computer aided design and computer aided machining I.e CAD/ CAM System. The resulting brackets by CAD process can have torque in base , torque in face, or a combination of two.
  61. 61. IN/OUT specifications NOTE : IN/OUT Feature of pre adjusted brackets are fully expressed, because the arch wire lies snugly in the slot. A premolar bracket which is 0.5 mm thicker than normal brackets are used for the cases with small upper second premolars.
  62. 62. TIP specifications NOTE:TIP Features of the pre adjusted appliance is almost fully expressed. Upper and lower molar attachments have 0o tip. When placed parallel to the buccal cusps of the molars, this delivers 5o of tip in the uppers and 2o of tip in the lowers
  63. 63. Versatility of MBT system: 1. Options for palataly displaced upper lateral incisors.(-10o). 2. Three torque options for the upper canines(-7o,0o, +7o). 3. Three torque options for the lower canines(-6o, 0o,+6o) 4. Interchangeable lower incisor brackets-same tip and torque 5. Interchangeable lower premolar brackets-same tip and 6. torque Use of upper second molar tubes on first molars in non HG cases. 7. Use of lower second molar tubes for the upper first and second molars of the opposite side, when finishing the cases to a class II molar relationship.
  64. 64. Three torque options for the upper canines: (-7o, 0o,+7o) Effective torque control of the upper canines is necessary, because they are key elements in mutually protected occlusion. By using various tip and torque to the canines it is possible to position the canine in such way that it will fulfill it’s role in lateral excursions.
  65. 65. Three torque options for the lower canines: (-6o,0o,+6o) In some deep bite cases it is necessary to torque the canine crown labial and at the same time maintain the canine roots in alveolar bone.
  66. 66. Factors which govern the selection of canine brackets. 1. Arch form. 2. Canine prominence. 3. The extraction decision(tip control). 4. Overbite. 5. Rapid palatal expansion. 6. Agenesis of upper lateral incisors, where space is to be closed.
  67. 67. Dogherty Guage
  68. 68. INNOVATIONS OF M.B.T 1. SECOND PREMOLAR TUBES: ADVANTAGES:  Decreased occlusal interference of the opposing teeth,mainly in overbite and class II cases.  Comfortable to the patient.  Decreased bracket failure.  Decreased friction during the sliding mechanics.
  69. 69. 2. LOWER SECOND MOLAR MINI TUBES: Helpful in cases where, the inter-occlusal space and the gingival tissue do not allow the placement of regular banded molar tubes or bondable molar tubes.
  70. 70. 4.Lingual appliance Indirect bonding in laboratory procedure is indispensable in lingual treatment because of the variations of lingual tooth surfaces and the limitation of human eyes and hands in accurate bracket positioning. There are three methods to set up bracket positions in the laboratory that represent the evolution of the lingual orthodontics in lab procedures. 1. TARG(TORQUE ANGULATION REFERENCE GUIDE) 2. CLASS (CUSTOMIZED LINGUAL APPLIANCE SET 3. UP SERVICE) HIRO SYSTEM
  71. 71. The TARG The TARG, despite the anatomic variations of the lingual surfaces, permits to bond brackets in the laboratory at an accurate distance from the occlusal edge of each tooth with respect to horizontal occlusal plane.
  72. 72. The tooth orientation is made with a guage or torque blade. The model is tipped on a swivel base until the long axis of the labial face of tooth aligns with the specific guage curvature at the middle third of the tooth. This orientation allows us to pre-program torque and angulation(tip)before starting the treatment
  74. 74. The TARG with the thickness measurement system.
  75. 75. The two blades of the thickness measurement system.
  76. 76. The gap between properly oriented bracket base and the tooth surface is filled with resin.
  77. 77. In case of crowding, the bracket is decentered or rotated.
  78. 78. On the right incisor, the bracket is moved distally for overcorrecting. On the lateral, the bracket is bonded mesially to begin correction of the rotation. Once the rotation is parially corrected, the bracket is re-centered
  79. 79. 5. BEGG APPLIANCE. Off-centering the bracket to the rotated side will help to overcorrect the rotations. Anti-rotational effect is achieved by raising the flange of the bracket by welding 0.010’’ligature wire.
  80. 80. Modified placement of buccal tubes and elastic hooks.
  81. 81. J C O 1 9 7 7 Close-up of modified placement of buccal tubes and elastic hooks. M ar c h
  82. 82. Various gauges used for bracket placement.
  83. 83. Precision bracket placement instrument A. Micrometer for determining vertical height. B. Incisal rest arm controlled by micrometer. C. Plunger for separating bracket holding arms. D. Trigger for releasing bracket. E. Calipers to measure mesiodistal width of tooth at height of bracket. F. Bracket holding arms. A U G 1 9 8 9 G. Locking knob, released when rotating Instrument for use on opposite arch. H. Control knob for width-measurement calipers. I. Fiber-optic bundle In plunger for attachment to light-curing unit. J C
  84. 84. Labial slot machine. The labial surface of individual teeth is oriented to a stationary arch wire slot position.
  85. 85. Height Gauge Tweezer J C O A P R I L 2 0 0 2
  86. 86. Bracket Positioner J C O A U G U S T 2 0 0 0
  89. 89. Bracket Placement with the Preadjusted Appliance 1. Horizontal errors. Placing the bracket to the mesial or distal of the vertical long axis leads to undesirable tooth rotation. Such errors can be avoided by visualizing the vertical long axis—directly from the facial surface, or with a mouth mirror from the incisal or occlusal aspect. Some orthodontists even draw a line on the tooth to indicate the correct vertical long axis. Horizontal bracket placement errors can be avoided with careful technique.
  90. 90. 2. Axial or paralleling errors. If the bracket wings are not parallel to the long axis, the result will be unwanted crown tipping. These errors can be avoided in the same way as horizontal errors. Axial or paralleling errors can be avoided with careful placement technique.
  91. 91. 3. Thickness errors. Leaving excess adhesive under a portion of the bracket base or failing to conform the base accurately to the contour of the tooth can cause improper torque or rotation. This problem is overcome by expressing all excess adhesive from beneath the bracket during placement and by more accurate contouring. Excess adhesive beneath bracket base can cause thickness and rotational errors.
  92. 92. 4. Vertical errors. Improper vertical placement can lead to extrusion or intrusion of teeth, as well as to torque and in-out errors Improper vertical placement can lead to extrusion or intrusion and to torque and in-out errors.
  93. 93. Few Special Considerations
  94. 94. Gingival Concerns: 1. Partially erupted teeth. Young patients frequently have partially erupted teeth on which it is difficult to locate the centers of the clinical crowns. Because the apparent clinical crown is foreshortened, the tendency is to place the bracket too incisally or occlusally, especially with bicuspids and lower second molars. Partial eruption makes it difficult to visualize centers of clinical crowns.
  95. 95. 2. Gingival inflammation. This also causes foreshortening of the clinical crown, and the bracket again tends to be placed too incisally or occlusally. A. Typical patient with healthy gingivae. B. Same case with gingival inflammation in upper right quadrant, reducing apparent length of clinical crowns.
  96. 96. 3. Teeth with palatally or lingually displaced roots. Gingival tissue covers a greater portion than normal of the clinical crowns of such teeth, shortening the clinical crown.The bracket would be placed too incisally or occlusally. Lingually displaced root (right) can make clinical crown appear shorter.
  97. 97. 4. Teeth with facially displaced roots. This situation is often found with cuspids. The clinical crown appears longer, making the bracket placement too gingival. Facially displaced root (right) can make clinical crown appear longer.
  98. 98. Incisal or Occlusal Concerns 1. Incisal or occlusal crown fractures or tooth wear. With such teeth, the apparent clinical crown is shorter. The problem can be corrected by restoring the crown to its proper length or by estimating how long the crown was before the fracture or wear. Incisal crown fracture or tooth wear makes it difficult to visualize center of clinical crown.
  99. 99. 2. Crowns with long, tapered buccal cusps. Cuspids or bicuspids with long, tapered cusps often do not have adequate contact with the opposing teeth. If the bracket is placed in the center of the clinical crown, the adjacent marginal ridges will not be aligned. Improper placement can be avoided by selectively reducing the height of the cusp prior to bonding. With long, tapered buccal cusp, if bracket is placed in center of clinical crown, adjacent marginal ridges will not be properly
  100. 100. Conclusion Accurate bracket positioning is essential, so that the built in features of the bracket system can be fully and efficiently expressed. This helps in treatment mechanics and improves the consistency of the results.
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