Tweed philosophy 2 /certified fixed orthodontic courses by Indian dental academy


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Tweed philosophy 2 /certified fixed orthodontic courses by Indian dental academy

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2.  Introduction :      History and evolution of the edgewise appliance. Dr.E.H.Angle, Dr. Charles Tweed, Dr.Levern Merrifield---contributions to the development of edgewise appliance The Tweed philosophy The Tweed technique The Tweed Merrifield philosophy The Tweed Merrifield technique Conclusion
  3. 3. Dr.Edward Hartley Angle  The edgewise arch mechanism was the brain child of this master technician.  By the time of Dr.Tweed,1930,with the introduction of milled brackets, S.S ligature wires it had evolved into a precision appliance, that demanded accurate fitting and placement of bands and attachments on teeth.
  4. 4. Introduction  The edgewise arch mechanism/appliance was Dr Angle’s last and greatest contribution to orthodontics ,after almost a lifetime devoted to improvement of orthodontic appliances.  Described it to Fedrick Noyes: “all you can do is push, pull or turn a tooth. This appliance is as fine as I can make it. I have given you the appliance. Now for God’s sake use it.”
  5. 5.  Edgewise mech was designed to place teeth into Angle’s concept of line of occlusion: “the line with which in form and position according to type, the teeth must be in harmony if in normal occlusion.”  Angle believed that there could be only one true line of occlusion and it must be the same as the architectural line on which the denture apparatus was constructed.  This ideal line was intended not only to govern the length and breadth of the dental arches, but also the size and pattern of each tooth cusp and inclined plane composing these arches.
  6. 6.  Laber : the best the orthodontist can do is to secure the normal relationship of teeth and correct general form of the arch, leaving the finer adjustments of individual typal form to be worked out by nature through her forces, which must in any event triumph finally.
  7. 7.  Angle’s theory: At last here was an appliance with which all necessary tooth movements, such as restoration of normal arch form, correction of all rotations and all en mass movements of teeth necessary for normal cuspal relationships could be achieved. He was absolutely correct when his treatment techniques were adhered to closely and no concern was raised to the resultant bimaxillary protrusion that was the usual aftermath of such treatment procedures.
  8. 8. Angle’s philosophy of treatment  Based on the then prevalent assumption that ,if cuspal interdigitation of teeth were made normal, stimulation by function would result in growth of basal bone structures.  Little or no thought was given to the inclination of the mandibular incisor teeth or to normal mesiodistal rel of teeth and their respective jaw bases and head structures.  It was assumed function would take care of such matters.  Extraction of teeth for orthodontic therapy wasn’t even an option .
  9. 9.  Research proved otherwise: The theory that stimulation by function could and would result in growth of maxillary and mandibular basal bones discarded. No scientific evidence found to indicate that it was possible to grow bones beyond their genetic potential.
  11. 11. E.H. Angle – Graduation 1878, experienced many technical problems and frustrations in treatment which irritated, motivated and inspired him to develop a standard appliance. His obsession for order motivated him to create the Angle System 1887 : this ultimately resulted in the multi banded edgewise appliance 5yrs before his death. 5 properties that appliance must have    SIMPLE : must push ,pull and rotate teeth STABLE : must be fixed on the teeth EFFICIENT : must be based on NEWTON’S 3RD LAW and anchorage  DELICATE : must be accepted by the tissues and must not cause inflammation and soreness  INCONSPICUOUS : esthetically acceptable
  12. 12. The standard appliance used by Angle Basic components of the standard appliance used by Angle: Traction screw, jack screw, attachment tubes, band material lever wire, arch wire,wrench
  14. 14. E-arch  In the late 1800s the orthodontic appliance was some sort of rigid framework to which the teeth were tied so that they could be expanded to the arch form dictated by the appliance.  E-arch was an improvement on this basic design.  It employed crown movement of teeth with simple anchorage.  Brass wire ligature and stationary anchorage in the molar area were used to expand all the teeth into normal occlusion
  15. 15.  Bands were placed on molar teeth and heavy labial arch wire extended around the arch. The end of the wire was threaded and a small nut placed on the threaded portion of the arch allowed the archwire to be advanced so that the arch perimeter increased.  Individual teeth were simply ligated to this E-arch.
  16. 16. E-arch appliance
  17. 17. Basic E-arch
  18. 18.  The heavy archwire was supplied in 4 designs: 1. Basic E-arch used with baker’s anchorage 2. Ribbed E-arch used in expansion by tying brass ligatures to arch wire 3. E-arch without threaded ends that fit into the molar sheaths, used with attachment for high pull headgear. 4. E-arch with hooks in maxillary wire ,used to move entire maxillary dentition distally.
  19. 19. Ribbed E-arch
  20. 20. E-arch with headgear
  21. 21.  Advantage: Simplicity  Disadvantge: Can deliver only heavy intermittent forces Capable of only tipping teeth to new position, no precise tooth positioning possible. Correction of axial inclination of teeth cant be accomplished.
  22. 22.  Angle concluded from his failures that it was necessary to bodily move teeth.
  23. 23. Pin and tube appliance  To overcome the inability of E-arch to perform precise tooth positioning, Angle placed bands on other teeth and used vertical tubes on each tooth into which soldered pins from a smaller arch wire was placed .  With this appliance tooth movement was accomplished by repositioning the individual pins at each appointment.
  24. 24. Pin and tube appliance  Orthodontist had to expertly solder pins, fit pins perfectly into tubes on the bands, remove the pins, move the pins along the archwire, solder pins again and fit pins once again into tubes on bring about tooth movement.
  25. 25. Pin and tube appliance  Disadvantage: 1. Relatively heavy base arch wire used, so spring quality poor and small adjustments were needed which were difficult to make 2. Construction and adjustment very difficult 3. Though theoretically great precision in tooth movement is possible, impractical for clinical use. Neverthless it was the first appliance with mechanism for root movement.
  26. 26. Ribbon arch appliance(1915)  Angle modified the tube on each tooth to provide a vertically positioned rectangular slot behind the tube…i.e,brackets with vertical slot.  Thus brackets were introduced with this new appliance.  Gold ribbon arch wire was placed into the slot and held with brass pins.  Had good spring qualities and efficient in aligning malposed teeth.
  27. 27. Ribbon arch appliance
  28. 28. Disadvantage:  not suitable for enmass tooth movement.  Mesial and distal tipping bends could not be incorporated into the archwire.  Poor root positioning control  Resiliency of the arch wire did not allow generation of the moments necessary to torque roots to a new position.
  29. 29. Edgewise appliance (introduced 1928)  To overcome the deficiencies of his previous appliances, Angle changed the form of the bracket in the ribbon arch appliance. He placed the slot in the centre and oriented the slot from vertical to horizontal and inserted a rectangular wire rotated 900 to the orientation the wire had with the ribbon arch bracket (hence the name edgewise)
  30. 30. Edgewise appliance
  31. 31.  Edgewise bracket when formed consisted of 3 walls within the bracket.  0.022 x0.028..  Soft gold originally which tended to deform easily  Slot oriented horizontally.
  32. 32.  EDGEWISE APPLIANCE metal bracket …. slot in center, placed in horizontal plane 0.022 x 0.028” rectangular wire in narrow/ edgewise position Unique feature  rectangular wire in rectangular slot  twisting / torquing forces could be imparted to control the axial inclination of teeth So possible to move teeth in all 3 planes of space with a single arch wire.
  33. 33. Evolution of edgewise brackets  Single width brackets: 0.050 inch wide and soldered to gold band material. because of the narrow width, the bracket by itself was ineffective for tooth rotation. so gold eyelets were soldered at appropriate positions on the band..ligature tied from eyelet to archwire to effect rotations…needed repeated tying. time consuming and inefficient.
  34. 34. Evolution of edgewise brackets  Two brackets on a single tooth. the two brackets were placed so as to effect rotation of tooth.
  35. 35. Evolution of edgewise brackets  TWIN BRACKET: (siamese twin brackets) Swain..originator of the idea. two edgewise brackets joined together on common base. 0.05 inch distance b/t the two. initially used only on centrals and molars. later narrower width brackets for other teeth.:4 types: extra wide, standard, intermediate and junior.
  36. 36. Evolution of edgewise brackets  Advantage of twin bracket: 1. effective for rotation correction. 2. greater axial control 3. incorporates positive control:once tooth has been derotated mere tying of wire to bracket with ligature maintains the tooth in its corrected position.
  37. 37. Evolution of edgewise brackets  Disadvantage: because of the increased width of the twin bracket, the amount of wire available b/t brackets on the arch decreased. Adverse effect on inherent resiliency of archwire. also in closing loop arch wires and second order bends,decreased interbracket span interferes with amt of closing action that can be attained.
  38. 38. Evolution of edgewise brackets  Lewis bracket: another approach to address problem of rotation correction soldered auxilary rotation arms that abutted against the bracket,thus offering lever arm to deflect archwire and derotate the tooth.
  39. 39. Evolution of edgewise brackets  Steiner brackets: Flexible rotation arms incorporated…so did not depend entirely on resiliency of archwire for tooth rotation.  Broussard bracket: addition of 0.0185 x0.046 vertical slot to accept a doubled 0.018 auxillary wire.
  40. 40. Dr.Charles.H.Tweed
  41. 41. CHARLES H.TWEED : Graduated from an improved Angle course in 1928 at the age of 33yr. Helped Dr.Angle in publishing an article in the dental Cosmos. Returned to Arizona and in Pheonix established the First pure edgewise speciality practice in U.S. For the next 2yr with Dr.Angle’s advise followed edgewise technique . Dr.Angle urged his dear student to : 1. Dedicate his life to the development of the edgewise appliance 2. To make every effort to make orthodontics as an specialty within the dental profession. Following advise Dr.Tweed instigated the first orthodontic specialty law in the U.S.. In 1929 first law limiting the practice of orthodontics to specialists was passed ; Dr.Tweed received certificate no1. in Arizona to become the first certified specialist in orthodontics in the U.S.
  42. 42.  Aug 11, 1930, Angle died at age of 75yr.  Tweed held to Angle’s conviction that one must never extract teeth, but this lasted for only 4yrs.In 1932 published article in Angle orthodontist “reports of cases treated with Edgewise Arch mechanism.”  What he observed in his patients during retention was so discouraging for him that he almost gave up practice. He devoted the next 4yr studying his successes and failures.he made a most important observation:  Lack of harmony in facial contour was in direct proportion to the extent to which the denture had been displaced mesially into protrusion.  Upright mandibular incisors frequently were related to post treatment facial balance and succesful treatment. To position mandibular incisors upright ,he concluded one must prepare anchorage and extract teeth.
  43. 43.  He selected failed cases and treated them with premolar extractions.  Was called a traitor ,faced critisism.  In 1940 he produced case reports of the retreated cases.
  44. 44.  Tweed made considerable effort to place mandibular incisors at 90 +/- 5 deg to MP without resorting to removal of teeth. In some cases this was achieved by over expansion of dental arches , but too often at the expense of impacting both Unerupted 2nd and 3rd molars. The aftermath of such treatment was relapse and damage to investing tissue.
  45. 45. Importance of identifying growth trends of patients 1.Type A growth trends : middle and lower face are growing forward and downward in unision with no change in the ANB angle. growth is aprroximately equal in both vertical and horizontal dimensions. if molar relationship is class II and the ANB exceeds 4.5deg its type A subdiv growth trend. It is better to place the patient on Kloehn cervical Headgear to restrain maxillary growth. Prognosis is good because the point B is moving forwards as the maxillary denture is moved posteriorly.
  46. 46.  Type B growth trend : the middle face is growing forward more rapidly than the lower, ANB increases in size with growth. if ANB is <4 deg prognosis is fair,one may expect reasonably good facial changes and good occlusion. if ANB 7-12 deg prognosis poor. Growth of the middle and lower face is predominantly in the vertical dimension.
  47. 47.  Type C growth trend: the lower face is growing forward and downward more rapidly than the middle face, with a decrease in the size of the ANB. prognosis very good from the point of view of facial esthetics. But during retention one has to observe for any lingual tipping of mandibular incisors or labial tipping of maxillary incisors. Prolonged retention may be required depending on the type of perioral musculature. Regardless of the size of the FMA , when the growth is mostly in the horizontal direction the growth trend is type C subdivision
  48. 48. TWEEDS CONTRIBUTIONS: a) Emphasized the 4 objectives of orthodontic treatment with emphasis & concern for facial esthetics. 1.the best balance and harmony of facial lines 2.Stability of dentures after treatment 3.Healthy mouth tissues 4.An efficient chewing mechanism b) Developed the concept of uprighting teeth over basal bone with emphasis on the mandibular incisors c) Made the extraction of teeth for orthodontic correction acceptable & popularized extraction of 1st pre molar. d) Enhanced the clinical application of cephalometrics.
  49. 49. e. Developed diagnostic facial triangle to make cephalometrics a diagnostic tool as well as a guide in treatment & evaluation of treatment results. 1. the normal range of inclination of the mandibular incisors to MP was 90+/- 5deg. (IMPA) 2. when he was working on why he could not make his unfavorable patiens beautiful like his favorables even with identical treatment, he found out that the FMA was the difference (recognised the importance of different growth trends) norm=25 deg, range=16-35deg; extraction of teeth was more necessary in patients with FMA >30deg. 3. 3rd angle FMIA was 65 deg. the size of the FMIA was found crucial in creating satisfactory facial esthetics with orthodontic treatment.
  50. 50. Tweed’s diagnostic facial triangle
  51. 51. f. Developed concepts of orderly treatment procedures & introduced anchorage preparation as a major step in treatment g.Developed a fundamentally sound consistent pre orthodontic guidance program using & popularizing serial extraction of primary & permanent teeth.
  52. 52.  Angle gave orthodontics the Edgewise bracket ,but Tweed gave the speciality the appliance.  The TWEED PHILOSOPHY was born.  He devoted 42yrs of his life from 1928 till his death on Jan 11,1970 to the advancement of edgewise appliance.
  53. 53. Levern Merrifield LEVERN MERRIFIELD 1953 : took TWEED course 1960 : selected by Dr.Tweed to be codirector and continue his work on edgewise appliance. 1970 : Director  study of orthodontic dentistry & development of edgewise appliance
  54. 54. Merrifield’s contributions A.Diagnostic concepts: Introduced diagnostic analyses which allow clinicians to determine whether and when extractions are necessary, if indicated which teeth to be extracted. 1. The dimensions of the dentition :anterior limit ,posterior limit ,lateral limit and vertical limit exists..these limitations must be recognised and treatment designed to conform to these limitations when normal muscle balance exists.
  55. 55. Merrifield’s diagnostic concepts 2.Recognise the dimensions of the dentition and treat for maximum facial harmony and balance : essentially 3 factors affect facial balance:  Position of teeth  Skeletal pattern  Soft tissue thickness : total chin thickness and upper lip thickness must be equal Careful consideration of these factors will enable the clinician to determine whether dental compensation will improve facial balance.
  56. 56. Upper lip thickness and total chin thickness If the total chin thickness is lesser than upper lip thickness, the anterior teeth must be positioned upright further to facilitate a more balanced facial profile because lip retraction follows tooth retraction
  57. 57. Some measurements to judge facial balance: 1. Profile line 2. On frontal view vermilion border of the lower lip should bisect the distance between the bottom of the chin and the ala of the nose. 3. FMIA : Tweed believed this angle was significant in establishing balance and harmony of the lower face. Related to FMA. For FMA 22-28 deg, FMIA 68deg Standard : FMA 30 deg ; FMIA 65deg. dental compensation for a high FMA requires additional uprighting of flared mandibular versa. 4. Z – angle : indicative of soft tissue profile and more responsive to maxillary incisor retraction than FMIA 70-80 deg normal range 75-78 deg ideal, depending on age and gender.
  58. 58. Profile line in a balanced face  When facial balance is present, the ideal relationship of profile line is to be tangent to the chin and the vermillion border of both the lips and should lie in the anterior 1/3rd of the nose.
  59. 59. Profile line in a face not in balance
  60. 60. Merrifield’s Z-angle and FMIA Z- angle : 70-80 deg range 75 -78 deg ideal Maxillary incisor retraction of 4mm allows 4mm of lower lip retraction and 3mm of upper lip response
  61. 61. Merrifield’s diagnostics concepts 5.Skeletal factors in facial balance: (cranial disharmony ) FMA,IMPA,SNA,SNB,ANB, Ao-Bo,Occlusal plane angle, PFH,AFH,facial height index (0.69),facial height change ratio Merrifield and Gebeck reported a 2:1 increase in PFH compared to AFH in successfully treated class II patients. 6.Jim Gramling’s probability index: observed that in successfully treated class II patients FMA was controlled , FMIA increased, IMPA reduced , Z-angle increased , AO-BO reduced mandibular incisor position was corrected.
  62. 62. Merrifield’s diagnostic concepts Probability index suggests that the following pre treatment conditions might be necessary for Class II treatment success : FMA should be 22-28 deg . ANB should be 6 deg or less . FMIA should be greater than 60 deg . Occlusal plane should be 7 deg or less . SNB should be 80 deg or more .
  63. 63. Merrifield’s diagnostic concepts Differential diagnosis analysis system Cranio facial Analysis : Vertical component : FMA :22-28 deg AFH/PFH ratio : 0.65 to 0.75 Occlusal Plane to FH Horizontal component: SNB ANB Z-angle
  64. 64. Merrifield’s diagnostic concepts Differential diagnosis analysis system 3. Total space analysis: 3 parts: a. Anterior space discrepancy analysis: anterior tooth arch surplus/deficit :space available in mandiular arch from canine to canine and sum of mesiodistal dimension of six anterior teeth….+… cephalometric discrepancy (the amount of space required to upright the mandibular incisors for optimum facial balance) b. Mid arch discrepancy : mid arch tooth discrepancy = diff b/t available midarch space and mesio distal width of 1st premolar, 2nd premolar,1st molar, space required to level curve of spee. + occlusal disharmony : measure distance b/t maxillary premolar buccal cusp to embrasure b/t mandibular 1st and 2nd premolar. (difficulty factor of 2)
  65. 65. Merrifield’s differential diagnostic analysis system c. Posterior space analysis: Posterior tooth arch discrepancy: space available = distal of mandibular first molar to ant border of ramus along occlusal plane. required space = sum of mesio distal width of 2nd molar and 3rd molars. Most easily recognisable sign of post space deficit is late 2nd molar eruption.
  66. 66. Merrifield’s treatment concepts 1.Directional control during treatment 2.Sequential tooth movement 3.Sequential mandibular anchorage preparation 4.Organisation of treatment into four orderly steps that have specific objectives.
  67. 67.
  68. 68.
  69. 69. Seventh objective of treatment 1. Clinician must position and arrange teeth for maximum 2. 3. 4. 5. 6. 7. facial and dental esthetics. Functional efficiency Health of teeth,jaws,joints and surrounding tissue. Stability. Harmonize correction with growth in growing patients. Position the dentition so that it is in state of continual harmony with its environment. The clinical objectives must be pursued in an ethical, moral and compassionate manner with overriding concern for public welfare.
  70. 70.
  71. 71. The TWEED philosophy and technique
  72. 72. Tweed philosophy 1.That practically all malocclusions are characterized by a forward placement of teeth in relation to their basal bones. Malocclusion is but a symptom of failure in growth of the bones upon which the alveolar processes which form the bony support of the teeth is built.
  73. 73. Under normal conditions ,i.e normal growth of the basal bones have occurred Erupting teeth under influence of muscular forces and ant component of occlusal forces Teeth are located in proper position on basal bones that the predetermined plan of occlusion called for.
  74. 74. If there is retardation in forward growth of the jaws during growth period Erupting teeth Under the influence of muscular forces and ant component are guided to locations where there is a balance of force play up on them. But the basal bone has failed to grow forward to harmonize with this plan So teeth get placed too far forward in relation to the basal structures.( noticed in incisors)
  75. 75. Tweed philosophy contd. 2)That the establishment and maintenance of stable anchorage is the fundamental factor in successful orthodontic treatment and should be the initial concern of the operator.  This is the outstanding feature of Dr.Tweed’s philosophy and all other features are built around it.  His first efforts in treatment were always directed toward establishing a firm anchorage from which to work.  This anchorage is not visualized in terms of passive stabilization but rather in the form of dynamic resistance.
  76. 76. Tweed philosophy contd.  He believed any clinical orthodontist who wants to routinely create excellent facial changes for their patients, will recognise the importance of and will prepare anchorage routinely in their practices.
  77. 77.  The degree to which anchorage should be prepared will vary considerably.  Unless one is purposely wanting to move the mandibular buccal segments forward or to move point B downward and backward for some specific reason, the terminal mandibular molars must always be upright to prevent their being elongated when class II intermaxillary force is used.
  78. 78.  Tweed philosophy contd. Classified anchorage preparation into THREE categories : 1. First degree anchorage preparation: minimal anchorage preparation required. applicable in : malocclusions with ANB 0-4deg ,facial esthetics are good, total discrepancy does not exceed 10mm. True class III or Psuedo class III cases. mandibular anchor molars uprighted /maintained in their upright positions to prevent being elongated by Class II elastics. The direction of pull of the elastics in function, will not exceed 90 deg when related to the long axis of the terminal molars.
  79. 79.
  80. 80. Tweed philosophy contd. 2.Second degree anchorage preparation: necessary for malocclusions in which ANB > 4.5 deg facial esthetics demand that point B moved anteriorly and point A posteriorly. class II cases, accompanied by type A, type A subdivision type B, type B subdiv growth trends. anchor prep: When 2nd molars erupted they are always banded. Mandibular terminal molars tipped more distally so that their distal marginal ridges are at gum level. the direction of pull of class II elastics rel to long axis of terminal molars should be greater than 90 deg during function, so that terminal molars will be further depressed rather than elongated.
  81. 81.
  82. 82. Tweed philosophy contd. 3.Third degree anchorage preparation : total anchorage preparation necessary in severe malocclusions where total discrepancy 14- 20mm ,ANB doesn’t exceed 5 deg. class I cases with exceedingly irregular teeth, bimax case with mesially inclined teeth. anchor prep: Jigs required all 3 posterior teeth- 2nd molar, 1st molar ,2nd premolar tipped to distoaxial inclinaiton to such a degree that distal marginal ridges of the terminal molar below gum level
  83. 83.
  84. 84. Tweed philosophy contd. 3)That the teeth, like inanimate objects, best resist the force of displacement when tipped to the angulation that offers the most advantageous mechanical resistance against the pull of dislodging forces. They are ultimately best stabilized when they overlie the basal ridge of bone comprising that portion of the body of the mandible and maxillae from which the alveolar processes take their origin.
  85. 85.  Teeth tipped to a angulation that offers the most advantageous mechanical resistance against the dislodging for force of the elastics.
  86. 86.  It was believed at that time that-“An undisturbed tooth affords the best resistance to movement.”  Tweed-It is impossible to band a tooth that’s in tight contact with a neighbor and have it undisturbed.  Reatin –when teeth are tipped distally as during Anchor prep, osteoid tissue is laid down adjacent to mesial surface of the tooth being moved distally. This new calcified bundle bone doesnt enhance the resistance to tooth movement when force is applied ;eg. Class II elastics.
  87. 87.  Why are the stakes of the tent slanted such that the pull of the tent ropes against the stake would not exceed 90deg? Ans: If the stakes are positioned too vertically into the ground, when a strong wind blows, the stakes will be pulled upward and toward the tent and the tent will be uprooted.The stakes should be positioned at an angle which will draw them deeper in to the ground by the pull of the tent ropes
  88. 88.  Using this simple mechanical principle, Dr.Tweed said anchorage preparation is mechanical in nature.(he saw it from a mechanical point of view than physiological)  If the teeth in the buccal segments of the mandibular denture are positioned upright, and terminal molars tipped back like tent stakes, so that the pull of the intermaxillary elastics, when related to the long axes of terminal molars ,does not exceed 90deg when the mouth is functioning, the entire mandibular denture will be more stable and better able to resist forward displacement.
  89. 89.  But if we leave the anchor molars in their undisturbed mesially inclined positions,the action of class II elastics being upward and forward, the terminal molars will be elevated and uprooted.
  90. 90.  If this is allowed to occur, it will be followed by excessive depression of the mandibular incisors, with a drastic and unecessary alteration of the occlusal plane…the FMA will open up and point B will drop downward and backward as the entire mandibular denture is tipped and displaced forward into protrusion.
  91. 91.  In the use of intermaxillary force, it was Dr.Tweed’s contention that the teeth in the anchorage denture must be placed in distal axial inclination if they are to be expected to resist forward and occlusal strain of elastics.
  92. 92.  The incisors in the anchor denture must be adjusted in lingual axial inclination to give their added support against forward movement of the entire anchorage base.  This is aptly termed DYNAMIC ANCHORAGE.
  93. 93. Dynamic stationary anchorage  In the use of intermaxillary force, it was Dr.Tweed’s contention that the teeth in the anchorage denture must be placed in distal axial inclination if they are to be expected to resist forward and occlusal strain of elastics.  The incisors in the anchor denture must be adjusted in lingual axial inclination to give their added support against forward movement of the entire anchorage base.
  94. 94.  Also teeth must also have adequate foundational support.  The mandibular incisors are the most difficult to retain permanently in perfect alignment.  Dr.Tweed carried these teeth lingualy and placed them such that their roots are overlying the bony ridge arising from the mental area of the body of the mandible. “placing the incisors on the ridge”  When so relocated incisors showed no tendency of returning to positions of malocclusion than do buccal teeth.
  95. 95.  So important did Dr.Tweed consider this factor to be that it became his primary objective in treatment and all other dental units in both dentures are subsequently adjusted to harmonize with such repositioned incisors.  The 1st molars which were looked upon as the key teeth in treatment became factors of secondary importance in routine corrective treatment!!!!
  96. 96. Tweed philosophy contd. 4)That teeth are most readily moved when their property and power of mechanical resistance has been primarily reduced.
  97. 97.  When teeth that are to be moved are found to be at an angulation that they offer mechanical resistance to movement, it is best to change their angulation to such form that this mechanical resistance to movement is reduced to a minimum.  This way anchorage is conserved and tooth movement favored
  98. 98. Class II div 1  Maxillary incisors usually flared —this establishes a most effective stationary anchorage against their lingual movement by class II elastics..instead of being moved lingualy they will make a fine anchorage …strain the mandibular prepared anchorage.  When teeth that are to be moved are found to be at an angulation that they offer mechanical resistance to movement, it is best to change their angulation to such form that this mechanical resistance to movement is reduced to a minimum
  99. 99.  Lingual tipping of incisors brought about by flattened and slightly broadened 0.018 s.s (levelling stage)  0.020 wire-pot belly loop distal to brackets of canines,  slight expansion and flattening; exaggerated curve of spee placed in the archwire to prevent elongation of incisor teeth as they are tipped lingually
  100. 100. Tweed philosophy contd. 5)That all forces emanating from an orthodontic appliance must be synchronized if they are to be most effective in the mass stabilization or the mass movement of teeth.
  101. 101.  Usually one forgets that the denture has its component parts arranged on two planes of space. The incisors are placed in transverse or coronal plane while the buccal segments are on the anteroposterior or sagittal plane.
  102. 102.
  103. 103.
  104. 104.  So when using tip-back bends in the buccal segments and lingual torque in the incisor segment, the purpose of which modification is to effect distal crown tipping the degree of tip-back force must harmonize with the degree of lingual torque in incisor region ,else one force will work against the other.
  105. 105. Tweed philosophy contd. 6) When teeth are placed in positions of mechanical advantage to resist forces acting on them… Nature being an expert mechanic herself….offers biological compensations and adjustments…that more than counterbalance the loss of bone stability that results from the initial tooth movement made for the purpose of establishing these adjustments of mechanical advantage.
  106. 106.  Biologist’s studies on the effect of tooth movement on the bony walls of the alveolar process: (physiological viewpoint) : Anchorage was best conserved by the least amount of tooth movement possible in the areas desired for resistance of force application. It was expected to preserve the original bony trabeculae of alv process, on belief that undisturbed formation was most resistant to subsequent attack upon it by appliance adjustment.
  107. 107.  In the Tweed technique, teeth are shifted for establishing distal and lingual axial inclination and to move the mandibular incisors onto the ridge.  When properly prepared and bound together by proper edgewise archwire adjustments, this anchorage unit is far more stable than the anchorage arranged according to the idea of biologists.
  108. 108.  This is both mechanical and biological (the new bone formation taking place coincidental to the tooth changes) in action.  When the molar and premolar teeth are in distal axial inclination and archwire tied into the brackets, forward tipping of any of these units, that may subsequently take place ,will exert a downward pressure on the tooth next in line mesially.  Resistance to downward pressure on a tooth is believed to be the greatest of all resisting power because functional demands require this to be so.  Hence by adjusting the teeth like in tweed technique this power will be called into action for anchorage purposes.
  109. 109.  Resistance to downward pressure on a tooth is believed to be the greatest of all resisting power because functional demands require this to be so.
  110. 110. Tweed philosophy contd. 7) If malocclusion is a manifestation of forward positioning of the teeth in relation to their basal bones, then the dental units will best resist such forward displacement when the buccal teeth are in distal axial position and incisor teeth in lingual axial position.
  111. 111.  The natural forces acting on the dentition have a constant propelling force acting upon the denture and this tends to forwardly tip the crowns.  Such action is made more easy and effective if buccal teeth are in exaggerated mesial axial inclination and incisors in labial inclination.  Therefore this force will be best resisted by placing the buccal teeth in distal axial inclination and the incisor teeth in lingual axial inclination .  In this Tweed technique we place teeth in such strategic positions.
  112. 112. 8) by Robert H.W.Strang ,Will M.Thompson Every malocclusion exemplifies a denture that is stabilized by balanced muscular forces and this muscular balance must be preserved in treatment if stability in the end result is to be attained .
  113. 113.  A deformed denture is maintained in its state by balancing forces emanating from its environmental muscles.  There is a muscular balance inherent to each particular denture/dentition.  To have a stable result in addition to placing teeth over their osseous foundation, one must aim to preserve muscular balance present in original malocclusion.
  114. 114. 1.That practically all malocclusions are characterized by a forward placement of teeth in relation to their basal bones 2)That the establishment and maintenance of stable anchorage is the fundamental factor in successful orthodontic treatment and should be the initial concern of the operator.
  115. 115. 3)That the teeth, like inanimate objects, best resist the force of displacement when tipped to the angulation that offers the most advantageous mechanical resistance against the pull of dislodging forces. 4)That teeth are most readily moved when their property and power of mechanical resistance has been primarily reduced.
  116. 116. 5)That all forces emanating from an orthodontic appliance must be synchronized if they are to be most effective in the mass stabilization or the mass movement of teeth.
  117. 117. 6) When teeth are placed in positions of mechanical advantage to resist forces acting on them… Nature being an expert mechanic herself….offers biological compensations and adjustments…that more than counterbalance the loss of bone stability that results from the initial tooth movement made for the purpose of establishing these adjustments of mechanical advantage.
  118. 118. 7) If malocclusion is a manifestation of forward positioning of the teeth in relation to their basal bones, then the dental units will best resist such forward displacement when the buccal teeth are in distal axial position and incisor teeth in lingual axial position.
  119. 119. 8. Every malocclusion exemplifies a denture that is stabilized by balanced muscular forces and this muscular balance must be preserved in treatment if stability in the end result is to be attained .
  120. 120.  Dr.Tweed did not make major changes from how Dr.Angle used edgewise appliance.  He moved the teeth using the same arch wire modifications that were taught to him by Dr.Angle, however he used certain modifications/bends in a much more exaggerated form and much more frequently.
  121. 121.  He used round arch wires more often.  He used newly adjusted archwires b/t appointments during treatment than maintaining the original archwire from start to finish.This allowed accurate control of tooth movement
  123. 123. Tweed technique Dr.Tweed divides his treatment routine into three phases : 1.Anchorage preparation : consists of 2 procedures a) placing the mandibular incisors over their basal bone and giving them a lingual axial inclination by virtue of lingual tipping AND rearranging the axial positions of the buccal teeth, including the second molars, if possible to best resist any forward displacement ,. This is done by giving a distinct distal axial inclination ,gaining complete bracket seating in every tooth and then finally binding all the component elements of the denture into one unit by firmly tying back the arch wire to the molar sheath.
  124. 124. TWEED TECHNIQUE step 1:ANCHORAGE PREP contd. b) Changing the axial inclination of the maxillary teeth especially the incisors, to render their resistance to distal movement less effective ,particularly in class II div I.
  125. 125. TWEED TECHNIQUE:STEP 2 2. Enmass movement whereby malrelationship of the two dentures is corrected and normal inclined plane adjustment gained.
  126. 126. Tweed technique : step 3 3. Establishing correct denture form and completing treatment objectives.
  127. 127. Tweed technique—in brief 1.All teeth banded with bracket bands (staples) Light round wire 0.016 used for gaining universal bracket engagement (levelling =teeth brought to common horizontal level) any faulty bracket placement corrected
  128. 128. Step I  Gaining universal bracket engagement.  Levelling  molar tipping bends 45 deg placed. no attempt made to gain space for blocked out teeth till resilient 0.021x0.025 wire and class III elastics can be used to avoid forward movement of teeth crowns. space should always be gained by distal movemet of tooth crowns.
  129. 129. 2. Upper and lower 0.018 s.s adjusted to engage all brackets. archwire formation: req length of wire…arch form given…circular molar loop stop made…wire place in molar sheaths,canine markings,central and midline markings made. canine curves given,incisors segment curved to confirm curvature of the denture. passive adjustment to buccal teeth;no bends molar tipping bends 45 deg placed. no attempt made to gain space for blocked out teeth till resilient 0.021x0.025 wire and class III elastics can be used to avoid forward movement of teeth crowns. space should always be gained by distal movemet of tooth crowns. Archwire tied to all brackets (2-3weeks) Retied till bracket engagement gained
  130. 130. 3. 0.02 round wire formed and bracket engagement gained.(6weeks) 4 .Resilient edgewise archwire 0.021x0.025 used for bringing about tooth movements fabricaiton: markings made…bent to ideal arch form no bayonet bends given now
  131. 131.  Resilient edgewise archwire 0.021x0.025 used for bringing about tooth movements  in maxillary wire- moderate lingual torque given in canine and buccal segment; in the mandibular strong lingual torque given in the buccal segment. in the incisor segment of both either lingual or labial crown torque depending on what will gain passive bracket engagementproper deg of tip back bend given in anchor molar. Wire shaped in incisor and canine region; again torque checked for harmony. markings for bayonet bends made,bends palced 15 deg distal tip + lingual bend( to prevent rotaiton due to lingual torque in buccal segment) placed at anchor molar. thus universal bracket engagement is gained.
  132. 132. 5. No more tooth movement tried till class III elastics can be used, for this anchorage must be prepared in the maxiallry denture first. maxillary denture anchor preparation: All teeth banded…0.018 adjusted (6week) 0.020 adjusted..20deg distal tiping bend at anchor molar (6-9weeks)..
  133. 133.  0.021x0.025 wire…marked lingual torque in buccal segments placed, slight lingual torque in anterior segment placed,20 deg distal tip bend (anchor molar)…very mild distal tip bends at canine, premolar and 1st molar area. hooks placed on archwire for occipital anchorage (to avoid forward root movement due to distal tip bend and lingual torque)….6-9 weeks
  134. 134. Maxillary anchor preparation 0.025x0.028 stabilizing wire ….first passive bracket engagement gained by placing the same deg if tip back bends and lingual torque as in the previous wire..strong tip back bend + lingual bend in anchor molar area… next appointment tip back bends stepped up… anchor tip back bends stepped up…torque in incisor segment increased…torque in buccal segmetns increased to be in harmony with anterior torque..headgear to be worn atleast 10hr in night. MAXILLARY ANCHORAGE PREP complete .
  135. 135.  Mandibular archwire: mandibular anchor preparation:
  136. 136. Mandibular anchor preparation  0.021x0.025 ….10 deg tip back canine ,premolar and molar area placed…greater tip back placed at anchor molar….lingual torque increased in incisor area…balance b/t distal tip in buccal segment and lingual torque in anterior segment maintained  keeping in mind the fact that movement of incisor roots ,under the influence of lingual torque is more easily and quickly effected than is the distal and lingual tipping of tooth crowns in the denture under the influence of the intermaxiallry elastics…it is considered good to maintain incisor lingual torque at a lesser degree than distal tiping bends. if required the torque can later be stepped up.
  137. 137. class III elastic hooks soldered on archwire (occlusal surface) two kinds of class III elastics given-light and time and night time wear.(patient warned about the chinless expression that may be observed…transient and will disappear when class II elastics are subsequently used to move maxillayr teeth distally) Unless the class III elastics are worn steadily the mandibualr teeth roots will move forward instead of their crowns moving distally….if head gear not worn, the maxillary anchorage will be weakened and forward displacement of teeth will take place…so patient co-operation very important.
  138. 138.  Mandibualr anchor prep continued: Distal tipping bends stepped up once in 6weeks…lingual torque proportionately stepped up…new wire used if deformed.  Mandibular anchorage and correct denture locaiton may be considered satisfactorily established when the incisor roots overlie the basal ridge and their crowns exhibit a distinct lingual axial inclinaiton and  when the canine, premolar and molar teeth are in distinct distal axial inclination .  the distal axial inclination of anchor molars should be greater than other buccal teeth.
  139. 139. Step II 6. Enmass movement to produce normal inclined plane relationship: .
  140. 140. 0.0215x0.028 that is in use in the maxiallry arch when class III elastics were worn are replaced by 0.021x0.025 resilient wire… harmonious tip back bends given. lingual torque and lingual molar bends duplicating the ones in previous heavy wire given.. molar stops and intermaxiallry elastic hooks soldered…tied to brackets to remain passive for 3 tip back bends are now given...lingual torque increased slightly in incisor area…class II elastics applied… occipital anchorage discontinued
  141. 141. mandibular anchorage watched carefully…molar tie ligatures retied at every appointment… at any sign of anchorage giving away...tip back bends, lingual torque, lingual bend increased in anchor molar… in other teeth proportionately tip back bens and torque increased…. still if anchor loss occurs…occipital anchorage applied to mandibular denture.
  143. 143. The appliance  Simplicity, efficiency,comfort hygeinic,versatality,esthetic.
  144. 144.  Neutral (no tip ,torque or inout) 0.022 slot dimension  Posterior bands  Anterior mesh pads  With single ,double width 0.022 brackets on six anterior teeth  Intermedeate single width brackets on premolar bands  Twin brackets on 1st molar  Heavy 0.022 edgewise tubes with mesial hooks on 2nd molar bands
  145. 145.       Arxhwires: 0.017 x0.022 0.018 x0.025 0.019 x0.025 0.020 x 0.025 0.0215 x0.028 inches  Different wire dimensions allow greater versatality and allow sequential application of forces at diff stages.  Objective is to enhance tooth movement and control with proper edgewise wire.
  146. 146. Auxiliaries used:  Elastics  Directionally oriented headgear: high pull J-hook headgear straight pull J- hook headgear  Patient compliance imperative
  147. 147. 1 order bends st  Knowledge of action and interaction and reaction of teeth to bends crucial.  Action and reaction of 1st order bends bring about contraction or expansion  Interaction of the 1st order bends can affect 3rd
  148. 148. 2 order bends nd In mandibular arch:  These used in the posterior segment of mandibular arch are antagonistic to teeth in anterior segment.  If proper directional control not used, and care not taken in application of these bends in a sequential manner…vertical control of anterior teeth will be lost.  These apply labial crown torque on the incisors..which is not desirable. This fact must be given careful consideration during archwire fabrication.
  149. 149. 2 order bends nd  In maxillary archwire:  Second order bends in the posterior segment are complementary to teeth in the anterior segment…  The reaction of the tipping forces produced by the 2nd order bends in the posterior segment intrudes the maxillary incisors and gives a lingual root torque effect to these teeth.
  150. 150. 2nd order bends
  151. 151.
  152. 152. 3 order bends rd  Mandibular arch:  3rd order bend reaction in mandibular archwire is       complementary to all teeth. Objective is to place some degree of lingual crown torque on all mandibular teeth. Posterior and anterior segment work together in action, reaction and interaction. Ideal 3rd order bends in mandibular segment: Incisor : -7deg Canines : -12 deg 2nd premolars and molars : -20 deg
  153. 153.
  154. 154.
  155. 155.  Maxillary arch:  Conversely 3rd order bends here are antagonistic.  Anterior segment needs no torque (0 deg) or slight lingual root torque.  Posterior segment needs lingual crown torque:  Canines and 1st premolar : -7 deg  Second premolars : -12 deg  Application of opposite torque force simultaneously in diff segments of same arch not wise.  In the maxillary arch it is best to apply active 3rd order bends sequentially and in only one direction at a time.
  156. 156.  Using Tweed’s concepts as foundation Merrifield developed force systems to simplify the use of edgewise appliance:  Tweed used 12 sets of archwires during treatment of a patient ; reduced to 4-5 sets  Merrifield’s sequential directional force technology.  Directionally controlled precision arch wire manipulation.
  157. 157. TWEED MERRIFIELD PHILOSOPHY Essentialy 5 concepts compose the Essentialy 5 concepts compose the philosophy: 1) Sequential appliance placement 2) Sequential/individual tooth movement 3) Sequential mandibular anchorage preparation 4) Directional force including control of vertical dimension which will enhance mandibular response 5) Proper timing of treatment
  158. 158. 1) Sequential applaince placement :  1st premolar extraction case: 2nd molars, 2nd premolars, canines banded, centrals banded/bonded ; 1st molars left unbanded Advantage : Less traumatic Easier Less time consuming Allows greater efficiency in arch wire action (longer inter bracket span in posterior seg) Larger dimension wire can be applied that is less subject to distorsion.  Once banded teeth respond to the force of arch wire additional teeth banded , sequence : After 1st appointment  maxillary 1st molars banded After 2nd appointment  mandibular 1st molars banded At 3rd/4th appointment lateral incisors bonded
  159. 159.  Initial archwires placed  1st molars not banded
  160. 160. 2) Sequential tooth movement: Tweed had advocated enmass tooth movement Advantage : Rapid and precise tooth movement because they are moved individually/in small units
  161. 161. Sequential tooth movement
  162. 162. 3) Sequential mandibular anchorage preparation: developed by MERRIFIELD “10 – 2” system. Tweed : Enmass anchor preparation;all compensation bends placed at one time in the archwire and class III elastics used for support ----result : Labially flared and intruded mandibular incisors
  163. 163. Merrifield technique – `10 – 2’ Force systems(10 ten teeth used as anchor units to tip 2 teeth) + High pull head gear for support rather than class-III elastics Tooth movement is controlled, sequential and precise….mandibular anchorage can be prepared quickly and easily by tipping only two teeth at a time to their anchor prepared position.
  164. 164. 10 -2 force system  10-2-6  First molar tipped tipped to Anchor prepared position
  165. 165.  Initial step of SMAP : IInd molar is tipped to its      desired anchorage prepared position. Space closed b/t Ist and IInd molars Compensating bend placed mesial to the IInd molar to maintain its tip Ist molar is tipped to anchor prepared position. Compensating bend placed mesial to molar to maintian tip IInd premolar tipped distally to APP.
  166. 166. Tweed- merrifield philosophy contd. 4) Directional force : hallmark of modern Tweed-Merrifield edgewise treatment is use of directional force to move teeth. Controlled forces which place teeth in the most harmonious relationship with their environment
  167. 167.  Critical to employ force system that controls the mandibular posterior teeth and maxillary anterior teeth  Control of vertical dimension crucial for the upward and forward force system to be a reality  to control vertical dimension we should control the Mandibular plane, palatal plane and occlusal plane.
  168. 168. Upward and forward force system  Resultant force vector of all forces should be upward and forward, giving opportunity for favourable skeletal change, especially in dento alveolar protrusion class II malocclusion correction
  169. 169. Upright mandibular incisors allows maxillary incisors moved up and back  Mandibular incisors upright over basal bone needed so that the maxillary incisors can be moved distally and superiorly
  170. 170. Downward and backward force system  If point B is allowed to move down, mandibular incisors are tipped off the basal bone and maxillary incisor drops down and back instead of being moved up and back.  This leads to a patient with lengthened face, a gummy smile, incompetent lips and a more recessive chin.
  171. 171. 5. Timing of treatment: Treatment should be initiated at the time when treatment objectives can be most readily accomplished. This may mean interceptive in the mixed dentition, or waiting for second permanent molar eruption before starting active treatment.
  172. 172. STEPS OF TREATMENT with Tweed – Merrifield Technique
  173. 173. STEPS OF TREATMENT CLASSIC TWEED MERRIFIELD EDGEWISE DIRECTIONAL FORCE TREATMENT can be organised into four force systems : 1) Denture preparation 2) Denture correction 3) Denture completion 4) Denture recovery
  174. 174. 1.DENTURE PREPARATION (apporx 6 months) OBJECTIVES: a) Leveling b) Individual tooth movement and rotation correction c) Retraction of both maxillary and mandibular canines d) Preparation of terminal molars for stress resistance
  175. 175. DENTURE PREPARATION continued.. Technique – sequential banding/bonding of teeth 0.018 x 0.025” resilient mandibular arch wire 0.017 x 0.022” resilient maxillary arch wire - loop stops flush with second molar tubes - Mandibular 2nd molar 150 effective distal tip - Maxillary 2nd molar 50 effective distal tip
  176. 176. DENTURE PREPARATION continued.. -2nd premolar offset bend mesial to 2nd premolar bracket placed to prevent canines from expanding - 3rd order bends passive in both upper and lower - High pull J-hook head gear used to retract maxillary and mandibular canines After 1st month terminal molar tip increased to maintain an effective 150 tip as tooth tip distal - Maxillary 1st molars banded, J hook head gear continued for canine retraction
  177. 177. Denture preparation  Initial archwires 0.017 x 0.022 resilient maxillary arch wire 0.018 x0.025 resilient mandibular arch wire J-hook hook head gear for canine retraction.
  178. 178.  Maxillary molars Banded after 1st month of treatment  Arches getting levelled off  Canine retraction with J-hook headgear continued
  179. 179. DENTURE PREPARATION continued As canines retract and arches are levelled ,the lateral incisors are ligated Power chain force used to aid canine retraction At each visitarch wires removed co-ordinated, checked for 1st,2nd 3rd order bends and religated - Canine retraction continued with power chain and HG force
  180. 180. Denture preparation  Canine retraction continued: using J-hook headgear and power chain
  181. 181. End of Denture preparation  Terminal molar anchorage: The mandibular terminal molar should be tipped to anchorage prepared position at the end of denture preparation.
  182. 182. END OF DENTURE PREP  Full dentition bracketed and leveled  Canines retracted , all rotations corrected  Mandibular terminal molars tipped distally into anchor prepared position
  183. 183. MERRIFIELD MODIFICATION in denture prep Mandibular arch   Start with 0.016” with incisal curvature, bent-in loop stops flush with molar tube  200 distal tip for 2nd molar (Tweed-150)  If progress slow use 0.018” wire Maxillary arch  Distal tip 100 (Tweed-50)  0.018” and 0.020” arch wires inserted about 1 month after their counter parts in their mandibular arch in contrast to simultaneous placement of maxillary and mandibular arch wires in classic Tweed technique
  184. 184. 2.DENTURE CORRECTION MANDIBULAR ARCH OBJECTIVES: 1. Retraction and up-righting of lower incisors to their planned positions 2. Completion of space closure 3. Achievement of posterior and mid arch axial inclinations that will permit proper functional co-ordination with the maxillary teeth
  185. 185. Denture correction :space closure  Mandibular wire: 0.019 x0.025 with 6.5mm vertical loop distal to lateral incisor bracket.  Maxillary archwire: 0.020 x0.025 with 7mm vertical loop.  Loop stops immediately distal to brackets of first molars  Loop stop in mandiblar arch wire incorporates a compensation to maitain 15deg terminal molar tip
  186. 186. Denture correction  Closing loop application: maxillary and mandibular closing loops are used to close spaces mesial to the distalized canines  Vertical support in maxillary rch through J hook HG (hook b/t central and lateral)  Vertical support for mandibular anteriro teeth through anterior vertical elastics
  187. 187. Denture correction: space closure complete  After space closure is complete, mandibular arch is level,curve of occlusion in maxillary arch maitained and the terminal molars remain tipped to an anchorage prepared position.
  188. 188. SEQUENTIAL MANDIBULAR ANCHORAGE PREPARATION  Sequential tooth movement concept Arch wire exerts active force on only 2 teeth, while remaining passive to other teeth in the arch. Thus, remaining teeth act as stabilizing anchor units as 2 teeth are tipped.(“10-2” anchorage system)
  189. 189. 1 step of SMAP st SMAP is initiated during Denture prep of treatment by tipping 2nd molar to 150 distal inclination
  190. 190. Mandibular anchorage preparation  After space closure in mandibular arch one checks to make sure the arch is level and 2nd molars are tipped to 15deg distal inclination (Readout)  10-2-6…first molar tipped to its anchrage prepared position
  191. 191.  0.019 x0.025 archwire with loop stops flush agianst 2nd molar tubes fabricated.  1st and 3rd order ideal bends are incorporated  Gingival hooks for high pull J hook HG soldered distal to central incisor bracket.  To tip 1st molar into APP,10deg distal tip placed 1mm mesial to 1st molar brackets.  Compensating bend to maintian 15deg 2nd molar tip placed just mesial to loop stop.
  192. 192.  10-2-6:  The second molars are now part of anchor unit /stabilizing unit and the first molars are the two teeth which receive the action of directional forces and archwire.  After 1 month arch wire removed, readout should show 5-80 distal inclination of 1st molars, 2nd molars should continue 150 read out
  193. 193. Mandibular anchorage preparation  Second premolar is tipped to its anchorag prepared position. 10-2-5.  Third and final step of SMAP – 50 distal tip 1mm mesial to 2nd premolar bracket, compensating bend between 2nd premolar and 1st molar to maintain 1st molar in APP
  194. 194. SEQUENTIAL MANDIBULAR ANCHORAGE PREPARATION continued….  At end of MAP, read-out will show : 2nd molar = 150 distal axial inclination 1st molar = 5-80 2nd premolar = 0-30
  195. 195. CLASS II FORCE SYSTEMS  A different system of forces may be used in patients with end-on or full cusp class II dental relationship.  A final diagnostic decision made and treatment planned based on – the ANB rel, maxillary posterior space analysis and patient co-operation…using the following guidelines:
  196. 196. 1. If the maxillary 3rd molar is missing or if ANB<= 5deg and patient is cooperative… best prognosis. If 3rd molar erupting then its best to remove it to facilitate distal movement of maxillary teeth. 2. If patient is cooperative, has a mild class II dental rel, normal vertical skeletal pattern, ANB 5-8deg and normally erupting 3rd molars…then advantageous to extract 2nd molars. 3. If ANB >10deg, poor patient cooperation, 3rd molars present…after maxillary and mandibular first premolar extraction space closure, either first molar extraction or surgical correction considered.( poor prognosis)
  197. 197. Correction of class II dental relationships Mandibular anchor prepared.  Mandibular 0.0215x0.028 stabilizing archwire fabricated with ideal first, second and third order bends. Wire passive to all brackets. Gingival spurs soldered distal to lateral incisor brackets. Wire seated and ligated. Terminal molar tied tightly to loop stop.
  198. 198. 2 molar distalization0.020x0.025  Maxillary archwire nd      wire with closed helical bulbous loops bent flush against the second molar tubes. Ideal 1st, 2nd and 3d order bends placed. Molar segment 7 deg lingual crown torque Gingival spur soldered to archwire distal to 2nd premolar bracket. Gingival high pull Headgear hooks soldered distal to central incisor brackets. Class II “lay on “ hooks with gingival extention for anterior vertical elastics soldered distal to lateral incisor brackets.
  199. 199. 2 molar distalization nd  Closed helical bulbous loops opened 1mm on each side and arch wire ligated in place.  Class II elastics of 8 ounces worn.  Anterior vertical elastics worn  High pull headgear worn.
  200. 200.  In about a month time the maxillary 2nd molar moves distally.helical bulbous loop reactivated until second molars have a class I dental relationship.
  201. 201. Class II force system:denture correction: maxillary 1st molar distalization  Coil spring 1.5 times distance b/t molar and premolar bracket trapped mesial to 1stmolar bracket.  E –chain from distal bracket of 1st molar to 2nd molar.  Class II elastics, headgear,anterior vertical elastics worn.
  202. 202. Class II force system:denture correction: maxillary 1st molar distalization  Maxillary first molar distalization  1st molars moved distally overcorrected into an class I dental relationship.
  203. 203. Class II force system :Denture correction : maxillary 2nd premolar and canine distalization  Spur distal to 2 premolar nd removed.  The coil spring is moved mesially and compressed b/t the lay on hook distal to lateral incisor and canine bracket.  Subsequently the 2nd premolars and canines are moved distally with elastic chains and head gear force.
  204. 204. By four months of active treatment, with monthly reactivation, posterior teeth should attain an overcorrected class I rel. Mandibular anchorage not strained if sufficient maxillary posterior denture area available and anterior vertical elastics worn.
  205. 205. Denture correction: Maxillary Anterior space closure  0.020x0.025 maxillary arch     wire with 7mm closing loops distal to lateral incisors. Ideal 1st, 2nd and 3rd order bends placed. Gingival headgear hooks soldered distal to central incisors. Closing loops opened 1mm per visit by cinching the loop stops to the molar tube. Milder 4-6 ounce class II elastics used instead of 6-8 ounces. Anterior vertical elastics and maxillary head gear worn.
  206. 206. Maxillary anterior space closure  After all maxillary space is closed… denture correction completed …denture ready for next step DENTURE COMPLETION.
  207. 207. Denture completion Mini treatment of malocclusion: The orthodontist repeats the force systems that are necessary, until the original malocclusion is overcorrected:  Ideal 1st,2nd,3rd order bends placed in 0.0215x 0.028” resilient arch wires.  Cephalogram traced to determine final mandibular incisor position and any minor control of palatal, occlusal and mandibular planes that may be needed.  Visual examination done for evaluation of lip line, maxillary incisor rel ,cusp seating, artistic positioning, need for lingual root torque of upper incisor .
  208. 208. Denture completion Maxillary and mandibular stabilizing archwires, along with proper elastics and headgear force used to complete orthodontic treatment.
  209. 209.  At end of denture completion        following characteristics should be readily observed: Incisors must be aligned. Occlusion overcorrected to class I rel. Anterior teeth edge-edge rel, minimal incisal guidance. Maxillary canines and 2nd premolars locked tightly into class I rel. Mesiobuccal groove of maxillary 1st molar must occlude in mesiobucal groove of mandibular first molar. Distal cusp of first molar and second molars must be slightly out of occlusion. All spaces must be closed tightly from 2nd premolars forward.
  210. 210. Denture recovery One must not strive for ideal final results at end of treatment, the ideal result will occur after all treatment mechanics discontinued and after uninhibited function and other environmental influences, active in post-treatment period, stabilize and finalize the teeth positions. When all bands removed retainers placed this crucial recovery phase begins. In this stage, forces involved are those of surrounding environment, primarily muscles and periodontium.
  211. 211. Denture recovery concept of over correction: if mechanical corrective procedures barely achieve normal relationships of teeth , relapse is inevitable…certain changes effected during treatment will tend to revert toward their original position. Tweed- Merrifield posterior disclusion : This is achieved at the end of treatment Called as Tweed occlusion is a transient occlusion state characterized by disclusion of second molars.
  212. 212.  The mesiolingual cusp of the maxillary first molar is seated in the central fossa of the mandibular first molar with the mesial inclined plane of the mesial cusp of the maxillary first molar contacting the distal inclined plane of the mesial cusp of the mandibular first .  This allows the muscles of mastication to exert the greatest force on primary chewing table in the midarch area.  The slightly intruded distally inclined maxillary and mandibular second molars now can reerupt to healthy functional occlusion without trauma or premature contact
  213. 213.  Transient occlusion: Occlusion must be over treated to a class I relaitonship.  The anterior teeth should be edge to edge.  The canines, premolars and 1st molars must have solid class I relationship.  The second molars must be tipped out of occlusion.
  214. 214. Final occlusion is characterized by the teeth settling into their most efficient , healthy and stable positions.
  215. 215.  All bands, except of 1st molars and canines removed, archwire ligated in both arches  Mandibular arch :canines ligated to each other  Maxillary arch, power chain placed from canine bracket to other,after7days remaining bands removed.  Muscles of deglutition, mastication and facial expression are actively involved in determining the final stable , esthetic relationship of teeth referred to as functional occlusion.  Each individuals own oral environment will determine the ultimate position of the dentition.Thus overtreatment allows patient the opportunity for maximal stability and functional efficiency
  216. 216. Conclusion Edgewise technique is more than just the application of headgear forces to cuspids. It is a group of integrated force systems designed to place the teeth, individually and collectively, in positions of physiologic and esthetic harmony with their environment. It is designed to achieve individualized tooth movements and precision to each patient, to achieve functional occlusion and optimal esthetics, to shorten treatment duration through use of sophisticated force systems.
  217. 217. It respects the dimensions of the denture . One must discard the idea that a bracket manufacturer can determine what is best for orthodontic patients.
  218. 218.
  219. 219.