Torquing in orthodontics /certified fixed orthodontic courses by Indian dental academy


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Torquing in orthodontics /certified fixed orthodontic courses by Indian dental academy

  2. 2. Torque is probably one of the most important and potentforces of orthodontic treatment mechanism with properunderstanding and with systemic technical approach torqueis not difficult to accomplish The operator’s ability to control torque properly willmean the difference between artistically treated case thathas all esthetic beauty desired in a finished denture and anordinary tooth straightening accomplishment that containsvery few of these desirable features
  3. 3. DEFINITION Torque being more related toengineering terms is defined as “The force systemtransmitted by and through a structural ormachine member, capable of producing purerotational displacement about the longitudinalaxis”.
  4. 4. In Orthodontics, as stated by Dr. EARMAN D. RAUCH “Torque is the force that enable theorthodontist to control the axial inclination of the teethand to place them in the harmonizing positions that areso desirable for a nicely finished results. Torque is theforce that gives the operator control over the movementof the roots of the teeth”.
  5. 5. WHY? WHEN? & HOW?Why ?• To bring about labiolingual movement of the teeth• To retain the teeth in the cortical bone• To avoid relapse• To give a natural finish to the dentition
  6. 6. When?• When there is uncontrolled tipping of the crown. In third order bends of finishing and artistic positioning in a pre adjusted edgewise system.• In pre surgical and post surgical phases for the precise placement for axial inclination of teeth.
  7. 7. How ?• Torque in fixed appliance can be employed in different ways 1. By giving a twist in an arch wire – commonly used in edgewise techniques 2. Torque exerted by the bracket itself – Pre adjusted edgewise appliance 3. By use of torquing auxiliary - widely used in Beggs technique .
  8. 8. BIO ENGINEERING PRINCIPLES OF TORQUE MECHANISM IN ORTHODONTICS• In a Rectangular wire, torque is incorporated by using a permanent twist in the arch wire, where as in a Round wire torquing auxiliaries are used to deliver third order couples to the anterior teeth.• The amount of torsional activation achieved upon complete appliance engagement is however actually less than this permanent twist angle. The principal portion of difference is the third order clearance between the arch wire and the bracket slot. This clearance may be computed from the actual cross section of the arch wire and occlusogingival bracket slot width. The third order clearance depends upon the actual wire in the slot dimensions and in effect, upon stiffness of the bracket slot• In response to the third order activation, the slot will open slightly as the wire attempts to deactivate.
  11. 11. • Pre Torque Brackets are sized, in part according to the third order angulation of their slots with respect faciolingual reference• Torque is determined in gram-millimeters or ounce inches• To quantify torque correctly the combination shaft stiffness and twist activation are necessary.
  13. 13. The chart represents the relative theoretical valuesof elastic stiffness, range and strength in torsion perunit length of common material for four rectangularwires The torsional stiffness of the largest wire is seento be five times that as the smallest wire in the table. The size of the wire and range is inverselyproportional. The other structural parameters are thewire material, longitudinal dimension and physicalcharacter of the wire.
  14. 14. To compare third order couple generated by therectangular arch wire and the torquing span, thedifference and the direction of the pairs of forces andthe moment arms should be noted. The force exerted by the rectangular arch wire aredirected nearly occlusogingivally whereas the forcepair from the torquing spur acts labiolingually. Thedifference in the direction meaningless with respectsto the action delivered to the dentition
  15. 15. The Begg torquing auxiliary is usually formed in0.012, 0.014 or 0.016 stainless steel wire. Thepurpose of the base arch wire is to counter theextrusive potential associated with activation ofauxiliary.
  16. 16. A NOTE ON FABRICATION OF THE SQUAREOR RECTANGULAR WIRE AND THE METHOD THEY DELIVER TORQUE ON THE TOOTH Square or rectangular arch wires are fabricated fromround wires by a process of rolling rather than drawing.The round wire is passed through a device called a Turkshead which is a set of two rollers positioned 900 to eachother and rolled to the desired dimensions. The edges ofthe wire remain rounded after rolling process, resulting inedge bevel. The edge bevel is expected to be a criticalfactor for actual torque expressed by a specific square or arectangular arch wire and bracket combination. Since theedges of the arch wire is first engaged the bracket fortorque delivery.
  17. 17. Largest edge bevels are observed on beta titaniumsegments due to the mechanical and wire properties of thisalloy. The amount of edge bevel on the wire will influencethe amount of torque exhibited by the wire bracketcombination for a rectangular wire in a rectangular molartube, the critical value of the wire dimension is thediagonal or wire cross section as shown in the figure
  18. 18. It is this dimension that contacts the wall of thelumen and engages the wire against further rotation.This with the variation in the tube dimension causesdeviation in torque clinically. This deviation in torquemay differ significantly enough to require diversetorque on left and right molars in the same arch.
  19. 19. METHODS OF TORQUING IN VARIOUS APPLIANCE MECHANICSBEGGS MECHANOTHERAPY : The torquing in BEGG is testimonial to the genius Dr.BEGG, both with regards to its concept and the designs. The special feature of BEGG appliance in separating the tooth moving forces from the arch wire forces gives at a unique advantage. Various torquing auxiliaries developed Dr.BEGG the 1. Spur design having 2,4 and 6 pairs 2. Mouse-strap for lingual root torque 3. Udder arch for labial root torque 4. Reciprocal lateral torquing auxiliary 5. Reverse torquing auxiliary 6. KITCHTON torquing auxiliary Single root torquing auxiliary developed Dr.Kesling
  20. 20. RECENT ADVANCES - Refined BEGG• 1. Reciprocal torquing auxiliary (‘SPEC’) Design• 2. Reverse torquing auxiliary for controlling the roots of the canine of the premolar by Franciskus Tan in November 1987.• 3. Buccal root torque and upper molars• 4. Labial root torque only in the lateral incisors• 5. MAA Auxiliary by Mollenhauer
  21. 21. TORQUING AUXILIARY WITH SPURSAction of the torquing auxiliary1. The auxiliary bent into a small circle, when fixed in the mouth, is spread out along the wider anterior curvature of the arch wire. The lingual torquing effect is an account of two factors. a. Firstly, the vertical plane in which the torquing auxiliary orients when fitted on two central incisors, is changed to a horizontal plane of arch wire when fully tied to it.
  22. 22. Secondly, when the torquing auxiliary isopened to a larger arc of anterior portion of thearch wire it rolls inwards.
  23. 23. Both the effects, force the tips of the spurs topress in a lingual direction against the gingival portionof the crown. Reciprocally the inter spur spans of theauxiliary tend to lift away in the labial direction.THUS A FORCE COUPLE IS CREATED. Thelabial forces are resisted by the bracket slots and thebase arch wire to which the auxiliary is tied. Thusaccentuating the action of lingual root moving forces
  24. 24. ABOUT “THE SPUR” 1. The Auxiliary should be constructed in 0.012premium plus wire (preferable pulse straightened)unlike in 0.014 or 0.016 special plus wire which werepreviously used. 2. The length of the spur does affect the forceproduced. A short spur will produce much greaterforce that will drop rapidly when the teeth start gettingtorqued, as against a longer spur that produces agentler and more constant force.
  25. 25. The length of the spur should be kept at about5 mm; but it should be varied depending on theclinical crown height, leaving it about 1 mm shortof the gum to facilitate proper hygiene
  26. 26. 3. Inclination of the spurs to the horizontal(occlusal) plane is kept 00. In other words, theactivation is 100%. 4. The distal leg of every spur is keptslightly shorter by about 0.5 mm, so that the distal legdoes not project incisally to the main arch wire ontying
  27. 27. 5. Activation of the spur a. The inter-spur span is curved as recommended by Dr.Kesling’
  28. 28. b. Kept straight as shown in Swain’s chapter
  29. 29. c. Angulated midway as in BEGG
  30. 30. d. As recommended by Dr.Jayade – normally size of the old 50 paise coin The force generated by the auxiliary increase with decrease in the diameter in the circle and vice-versa
  31. 31. Two of the modification commonly required in thespur design torquing auxiliary are as follows. a. Reverse labial torque on one or both thelateral incisors : Boxes at right angle to the plane of thespurs are made to lie at the incisal area of the lateralincisor(s). Crossover bends are made on either side of thelateral incisor bracket to permit the auxiliary to pass overthe base wire, similar to the bends described in the sectionon the MAA Torquing boxes on the canines for lingual roottorque : Instead of making spurs for the canines, boxescan be provided. The ends of this auxiliary need notextend beyond the canine area
  32. 32. MOLLENHAUER’S ALIGNING AUXILIARY (MAA) AND ITS MODIFICATIONS MAA auxiliary was developed by Dr.MOLLENHAUER and it was given the name as “AnAligning Auxiliary for Ribbon Arch Brackets”. TheMAA, attempts root control from the very beginning, ofthe treatment without significantly affecting the anchorageand overbite correction. This has become possible byusing a combination of a stiff base arch wire made from0.018” Premium plus, and ultra light root moving forcesfrom the MAA made from the 0.009” Supreme grade wire
  33. 33. Requirements for use of the MAAMollenhauer has enumerated the requirements as 1. It must generate very light root moving forces. Therefore, the wire size must not exceed 0.009”. 2. For the same reason, when reciprocal torque is required on adjacent teeth, the adjacent rectangles must not diverge by more than 45 degrees. 3. At the same time, the auxiliary must be able to resist deformation. Hence, it must be made in a highly resilient wire viz. Supreme grade (preferable pulse straightened)
  34. 34. 4. The base wire should be able to resist the vertical and transverse reactive forces from the MAA. Therefore, it must be made in 0.018” Premium Plus wire.5. In Mollenhauer’s application, the MAA is always engaged first and the main wire is engaged piggyback. The rectangles for lingual root torque lift away from the tooth surface, which are held down with the help of pins, thus indirectly transmitting the torquing action through the pins to the brackets onto the teeth.
  35. 35. Therefore, he recommends the thickest possible lock orhook pins (such as the pins for Ceramaflex brackets)
  36. 36. Advantages of the MAA• According to Molenhauer, the advantages of MAA are :1. Efficacy in intrusion and advantages retraction of the anterior teeth,2. Efficiency in rapid bodily alignment of the anterior teeth using gentle forces3. Stable results.4. Reciprocability of torquing forces on the in standing laterals or palatally placed canines.
  37. 37. 5. Periodontal advantages in such cases, because the gingival dehiscence associated with prolonged labial root torquing of such teeth during the 3rd stage is eliminated.6. A short stage III, because the early root control minimizes (uncontrolled) root tipping in the opposite direction7. Possibility of growing cortical bone at the A and B points
  38. 38. VARIOUS APPLICATIONS OF THE MAA 1. Originally, the MAA was introduced for bodilyalignment of crowded teeth. The looped arch wire like effect(expansion + de rotation + vertical leveling) was combinedwith lingual and / or labial root torque
  39. 39. VARIOUS APPLICATIONS OF THE MAA2. By bending more positive torque into the MAA, it can be used after the stage I as a braking mechanism. Mollenhauer strongly recommends applying labial root torque on the lower incisors in growing brachyfacial cases, to prevent their roots from lingualizing (which can happen due to intrusive forces and due to contraction of trans-septal fibers in extraction cases). This helps in a better profile control. The MAA can be used for labial root torque on the upper incisors in Class III cases
  40. 40. 3. In later writings, Mollenhauer described use of the same auxiliary for controlling the mesio-distal root positions from the beginning. He called this application ‘MAA-tip. A ligature wire tied to the auxiliary and to the pin transfers the tipping effect to the tooth.
  41. 41. 4. Modification can be used for reciprocal root torque
  42. 42. Other boxed Auxiliaries Mini versions of MAA ranging from 0.009” to0.012” and curvatures facing incisally facing incisallyor gingivally, for labial or lingual root controlrespectively. They are employed on two or morenumber of anterior teeth in either or both the arches.The force exerted by the boxes is varied, as per theindividual requirement, by varying the diameter of thewire from which the auxiliary is made, size of theboxes and acuteness of the curvature.
  43. 43. Obviously, the auxiliaries generating lighterforces are employed in the first and second stages oftreatment, while those generating higher forces aremeant for the third stage and sometimes in the secondstage as a breaking mechanicsa. Two boxes on the upper central incisors for lingualroot torque after the teeth are aligned
  44. 44. b. Two boxes on the in standing upper or lower lateral incisors for labial root torque.
  45. 45. ‘Jenner’ auxiliary two boxes on the upper orlower canines with very prominent roots. That ismade up of 0.012” wire. Lingual root torque exertedby the boxes reduces the prominence to facilitateanterior retraction
  46. 46. d. ‘SPEC’ design – Reciprocal torquingauxiliary – it is employed when two adjacent teethrequire root torque in opposite directions. One suchexample is an in standing lateral incisor needing labialroot torque and the adjacent canine needing lingualroot torque. This auxiliary is made of lighter 0.009 or0.010 could be used for controlling the rootmovements during the first and second stages. If needed in stage three it should be made of0.012.The box on the tooth requiring labial root torqueis placed incisal to main wire, while the box on theother tooth requiring lingual root torque sitspiggyback on the main wire .hence a crossover bend isrequired between the two adjacent teeth because theauxiliary has to cross over the main wire.varying theangulation between the planes of two boxes cancontrol the force generated by the auxiliary
  47. 47.
  48. 48. Some other torquing auxiliary designsa. Single root torquing auxiliary proposed by Dr.Kesling’. This is a very useful design for any tooth (excepting the molars) requiring torque in the labial or the lingual direction. It is particularly indicated on an UPPER PREMOLAR , which needs buccal root torque. To eliminate the cuspal interference from its hanging palatal cusp. It is convenient to place the long arm of the auxiliary piggy back over the main arch wire. Since the main arch wire may not be untied it could also lie occlusal to the base arch wire in the slot as well. The long arm should extend to three to four adjacent teeth when engaged in the brackets.
  49. 49. The long arm always faces mesially for thepremolar teeth. Depending on how the curvature ispointing before the auxiliary is tied, the torque generatedwill have lingual (palatal) or buccal root moving effect. For example, the auxiliary fitted with its convexityfacing upwards will have a buccal root torquing effecton the upper premolars, but the effect will be for lingualroot torque on the lowers, and vice-versa. The effect istransmitted by the vertical extension of the auxiliarythrough the bracket pillar onto the tooth; The long armcould face either mesially or distally on the anteriorteeth, and action will depend on how the curvature of thelong arm relates to the base arch wire. This auxiliary ismade up of 0.012 size Premium Plus wire. The forcegenerated by it can be varied by changing acuity of thecurvature. More acute greater is the force generated.
  50. 50.
  51. 51. b. Reverse torquing auxiliary for controlling the roots of canines or premolars proposed by Dr.Franciskus Tan - It was described for the labial root movement of a palatally impacted maxillary canine, whose crown has been aligned but the root is still placed palatally and needs labial root torque. If required for lingual root torque in other situations it is simply inverted well on the premolars made up of 0.012” P+ wire conjunction with a 0.018” or 0.020” inserted in the molar tube from the distal end. An offset is placed in the auxiliary to bypass the main wire rotated by 1800 for activating it
  52. 52. c. Buccal root torque on the molars – When the upper molar crowns roll buccally because of a lack of control during the third stage, their roots must be torqued buccally to lift their palatal hanging cusps. It is made in 0.014” size and is fitted in the round molar tubes alongside the main arch wire. It has ‘boot’ design occlusal extensions on the molars, and it is inserted from the mesial end of the molar tubes. The boot portion is twisted lingually and given a toe in, and the whole auxiliary is suitable contracted. The auxiliary need not be engaged in other brackets. It can be ligated to the main wire at 2-3 places on either side
  53. 53. d. Labial root torque only on the lateral incisors – This is made up of 0.012” size wire, and is placed with the convexity of the auxiliary facing gingivally. The auxiliary is engaged first in the incisor brackets, and the main wire is then engaged piggyback. The boxes extend labially on the incisal area of the crowns. This design is often required on the lower incisors in those cases where the central incisors and the canines are placed normally, and hence do not require reciprocal lingual root torque
  54. 54. e. UDDER ARCH - The upper arch is made up of 0.16 S.S.wire. The vertical loops of the auxiliary can be opened or closed as needed to assume accurate fit. The distal ends of the auxiliary is tied to the lower cuspid bracket. The vertical loops are slipped behind the main arch wire and the auxiliary is tided to one or two brackets to prevent dislodgement. It is very easy to insert and remove. This is used for the reverse torquing of the mandibular incisors.
  55. 55. f. Kitchton torquing auxiliary - It is used for applying torque force on the anterior teeth. Kitchton auxiliary can be used with Begg, edgewise.It is made up of 0.016 Australian wire. Coils in the midline assume gentle, and continuous torque force and also provide means of attachment to the main arch wire. It is of two types : 1) Small 2) Large
  56. 56. Mouse trapMouse trap design is very efficient but involves more time patience and skill
  57. 57. EDGEWISE MACHANOTHERAPY The edgewise arch appliance is the last of manycontributions of Dr.EDWARD H. ANGLE and wasintroduced to the profession by one of his laststudents, Dr.ALLAN G. BROADIE in 1929. It is anexacting appliance requiring the thoroughunderstanding and skill manipulation. This techniqueoffers excellent controls in the labiolingual,mesiodistal and vertical dimension
  58. 58. The classification of tooth movement associated with edgewise appliance seem to be based upon the type of movements rather than direction. i. Movement of the First order ii. Movement of the Second order iii. Movement of the third orderWe will see here movement of the Third OrderBefore we go into it we will have quick view over glossary
  59. 59. • Passive torque – torque for proper placement of the wire• Active torque – for active tooth movement• Progressive torque- increase of the torque value progressively as we go posteriorly in the dentition• Torque force is named according to the action upon the tooth crown. 1. Lingual torque – crowns are tipped lingually and roots labially / buccally 2. Labial or buccal torque – crowns are tipped labially or buccally and the roots lingually
  60. 60. THIRD ORDER MOVEMENTS : It is defined as the difference in inclination of thefacial plane of crown at its mid point in an idealocclusion. The third order bends better known as torque areplaced in the arch wire to effect buccolingual orlabiolingual root and crown movements in a singletooth or a group of teeth
  62. 62. Mass anterior lingual roottorque technique
  63. 63. Individual lingual Root torque central incisor area
  64. 64. Checking the amount of
  65. 65. Continuous posterior torque
  66. 66. Progressive Posterior Root Torque
  67. 67. PRE ADJUSTED EDGEWISE APPLIANCE: Until the mind 1970’s most fixed appliance therapy was carried out using the standard Edgewise bracket, either in a single or twin from having a 900 bracket base and brackets slot angulation. The Major disadvantage resulted from this treatment are; 1. Arch wire bending is time consuming and tedious.• The short comings of the bracket system and the extreme skill required of the orthodontists resulted in many under treated cases and the results are appeared artificial
  68. 68. Dr.Lawrence F.Andrews developed the straight wireappliance which became widely available in the mid1970’s. It was hailed by the clinician’s as a radical stepforward offering the dual advantages of less wire bending,coupled with an improved quality of the finished cases
  69. 69. TORQUE IN THE BASE Vs. TORQUE IN THE FACE Torque-in-base was an important issue with the firstand second generation pre adjusted brackets, because levelslot line-up was not possible with brackets designed withtorque-in-face. Torque in the base is said by Andrews to bea prerequisite for a fully programmed appliance – that is,one that produces acceptable results without arch wirebends, assuming the brackets are placed correctly. Albert H.Owen in 1980 conducted a study comparingRoth Prescription and the Vari Simplex Disciplineappliance of Alexander concluded that while torque in thebase had a sound theoretical basis, its effectiveness isgreatly influenced by the clinician’s success in accuratelyplacing the brackets
  70. 70. The torque in the base means that the bracketstem is parallel and coincides with the long axis of thebracket slot. But, with the brackets having torque in theface the slot is cut at an angle to the bracket stem,therefore their long axis do not coincide and are notparallel to each other
  71. 71. When the center of the bracket base isplaced on FA point the long axis of the bracket stemand bracket slot both are parallel to and are in linewith Andrew’s plane. But this is not possible withbrackets having torque in the face. Modern bracketsystems MBT are developed using computer aidedmachine the CAD-CAM system .this allows moreflexibility of design ,improved bracket strength. Thebrackets may be finished with all torque in base andtorque in face with absolute no difference in slotposition.
  72. 72. Ferguson concluded that the advantages of thetorque in base are largely theoretical, but it should bekept in mind that there are other advantages. Onesuch advantage is that the wings of the brackets withtorque in the face could bend under various forces
  74. 74. TORQUE ADDITION IN MBT APPLIANCE1. Additional palatal root torque for upper incisors and additional root torque in labial incisors2. Upper cuspid brackets with a normal -70 torque or 00 torque.3. Upper molar brackets with an additional 50 buccal root torque.4. Progressive Buccal ground torque in the lower cuspid and lower buccal segments
  75. 75. Note : Reversion of Bracket will reverse the torque prescriptionof the bracket but the tip remains the same
  76. 76. PLAY OF THE WIRE IN THE BRACKET• What is play ?• The difference between the slot with and the dimension of the arch wire is termed as play• * For every 0.0010 of play within the bracket slot 40 of effective torque as slots• * The amount of the play wire bracket interface is also influenced by ligation• *If the wire not fully engaged the effective torque decreases
  77. 77. * But generally there is some play between the bracket and arch wire even if the slot is filled with full dimension wire.* Because the dimension of the wire will be slightly smaller than the label dimension and slot width are larger than they are labeled
  78. 78. CONCLUSION My rationale on torque is, first give the teeth thenormal look. If you study untreated good occlusions that areesthetically pleasing, they also function well, so we emulatethat. However, good esthetics does not insure good function.It’s easy to straighten the upper teeth on the upper jaw and thelower teeth on the lower jaw, but if the upper and lower teethdon’t harmonize with each other when the mandible is in centricrelation then function will be poor. This is the most difficult partof orthodontics, harmonizing the upper and lower teeth to eachother with the mandible in centric relation. If this harmony isestablished then the natural “settling-in” of the teeth after theappliances are removed will produce good function in mostcases. Exceptions to this are open bite type cases which don’t“settle-in”. Therefore their finished occlusion with appliancesshould be more precise
  79. 79. Thank