Biomechanics in bagg /certified fixed orthodontic courses by Indian dental academy


Published on

The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit ,or call

Published in: Education
  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Biomechanics in bagg /certified fixed orthodontic courses by Indian dental academy

  2. 2. • 1. 2. 3. 4. 5. Only after achieving all the requirements of Stage I ie. Alignment. Elimination of crossbites. Correction of overjet & overbite. Midline correction Attaining Class I molar & canine relation. Stage II should be commenced.
  3. 3. Why Stage II is necessary? To prevent the posterior teeth from moving too far mesially.There would be insufficient space left to move anterior teeth. As it cannot be predicted how rapidly & to what extent posterior teeth will move mesially, it is unsafe to commence closure of spaces at the start of the treatment even in mild discrepancy cases.
  5. 5. Differential is defined as the difference of two or more motions or pressures. Tooth movement = force x time resistance The amount of force required to move teeth is in positive ratio to the surface area of the tooth root attached to the bone by the periodontal membrane.
  6. 6. In this technique advantage is taken of the principle, that , for moving anterior teeth with small root surface area , relatively light arch wire and rubber elastic force produce the most rapid movement with least disturbance to investing tissue. Also at the same time the light forces keep the anchor molars stationary. Conversely relatively large force causes the anterior teeth to resist the force, so that anterior force operate as anchor unit, as they move very slowly, while this large force causes the posterior teeth to move rapidly.
  7. 7. In an interdental force system (one that uses no auxiliaries, such as headgear and bite plates) the only appliance forces are those exerted between one or more teeth and one or more other teeth. In keeping with Newton's third law, these forces can only be equal and opposite. They are differential only in that they are exerted in opposite directions.
  8. 8. When these forces are exerted, they encounter tissue resistance, and it is tissue resistance that exhibits the differential response to equal and opposite forces which results in differential tooth movement. Simple crown tipping, for example, encounters little resistance and responds rapidly, but root tipping or bodily movement meets with high resistance and responds slowly.
  9. 9. Whether there is an optimum orthodontic force that will give best results , move the teeth at most favorable rate and with least tissue damage and pain? Storey and Smith concluded that there is an optimum range of force values that produces a maximum rate of distal movement of canines, and this optimum force did not produce any deleterious movement of the molar anchor unit.
  10. 10. • To move the canines distally 150-200 gms of force is the optimum range. • Maximum rate of mesial movement of molars occurred when force was increased to300-350 gms. • When force was below 150 gms for canine & below 300 gms for molars neither tooth movement occurred. • When heavy springs were activated , very little or no movement of canine occurred, instead molars moved mesially in remarkable fashion.
  11. 11.
  12. 12. When Dr.Begg adopted the principle of differential resistance for tooth movement in the first two stages, he took advantage of the significant difference between the types of resistance used and the amounts of force required to overcome them.
  13. 13. • Differential Force For Closing Extraction Space: According to Strang during closure of first premolar extraction space with edgewise mechanism, most of the space is closed by forward movement of anchor teeth instead of distal movement of canines. Failure was not due to inability to prevent anchorage but due to excessive force. So, according to Dr. Begg investigation made by Storey & Smith on light orthodontic force value is optimum to prevent any anchor loss, And is
  14. 14. In stage II the six anterior teeth are banded . Only first permanent molars are banded for anchorage. On each side . A light rubber elastic is stretched from the distal free end of arch wire to the intermaxillary hook The extraction space close rapidly , & anchor tooth hardly moves forward. To close remaining posterior spaces heavy elastic force is used to move the molars. Braking auxiliaries are used to prevent further distal movement of anterior teeth.
  15. 15.
  17. 17. Second stage Safety lock pins • Shoulder on labial surface of head ensure free mesiodistal tipping. • Lab-lin width of pin(0.020”) reduced 0.004” as compare to stage 1 pins to permit use with 0.018”or 0.020” inch wire.
  18. 18. Archwires 0.018/0.020” arch wires used. Only function – to maintain the corrections – achieved. ( bite opening, arch form & tooth alignment.). Stabilize the teeth against –Reciprocal forces – application of elastics or auxiliaries.
  19. 19. Objectives of Second Stage Maintain all corrections achieved during stage I.  M-D molar relationship maintained .  Original spaces b/w ant. teeth prevented from recurring – tying IM circles to cuspid brackets. Over rotations  of cuspids maintained – engaging brackets – offset on the teeth.
  20. 20. Objectives of Second Stage  of bicuspids held – replacing elastic threads with steel ligature ties.  of Central and lateral incisors – maintained – continued use of bayonet bends in the archwires. Bite opening maintained – continued use of bite opening bends & elastics. Correction of posterior crossbite maintained – modifying archwire or cross elastics. Close any remaining posterior spaces.  Wearing of horizontal elastics.
  21. 21. Commencement of stage II – Lateral ceph & stage models. Intraoral photographs. Lateral Ceph. compared with that of original radiograph.    antero posterior tooth movements in ref to each other & to face & cranium. anchorage maintained properly. inclination of the anterior teeth.
  22. 22. Anchorage bend  in comparison with that given in the stage I. Location:These are located 3mm in front of the mesial end of molar tube, approximately at the junction between the distal of the second premolar & mesial of fist molar.
  23. 23. Inserting and activating archwires Insert and check Degree of anchorage bend – - adequate to resist forward pull of elastics. - rest passively – halfway b/w brackets & mucolabial fold. Distal ends of the archwires – 1 – 2 mm beyond the distal end of the tubes. Anchorage bends sufficiently forward Toe-in bend is given to prevent molar rotation.
  24. 24. Horizontal or intramaxillary elastics for space closure. . Class II elastics – - relieved of correcting over jet. - used to maintain overcorrected positions of ant. & post. teeth Six elastics worn simultaneously.
  25. 25. Problems encountered with elastic wear
  26. 26. Tooth movements carried out during the 2nd stage of treatment Spaces in the buccal segment to be closed. Extn. space of four first premolars. Congenital absence of 2nd P.M. Lost buccal teeth due to caries. Spaces b/w teeth in Non-Extn cases. Exception. Extreme tooth spacing – small tooth size.
  27. 27. Auxillaries sometimes used in stage II
  28. 28. • Braking Auxillary make two point contact & prevents more distal tipping of the canines, so anterior segment becomes anchor unit and prevent further retraction. • Excessive force causes hyalinized tissue formation on the lingual side of anterior teeth which prevents tooth movement. • Posterior teeth having larger roots more force is required to move them mesially.
  29. 29. Teeth positions at the end of Stage II Extraction spaces closed. Crowns of upper and lower ant. teeth – tipped back or ‘dished in’.
  30. 30. Disadvantages of Conventional Begg Round wire – Ribbon bracket combination – no precise control for fine finishing. True intrusion of upper incisors – nil or minimal. Overuse of Class II elastics Lack of upper incisor intrusion. Undesirable proclination of lower incisors. Tipping of mandibular & occlusal planes. Uncontrolled tipping – root resorption. long third stage.
  32. 32. Stage II Auxillary: MAA auxillary. Base wire – 0.020”. Premium, premium+, supreme – in the order of increasing yield strength. Superior properties  pulse straightening, as against spinner straightening of older grades. Brakes to avoid excessive incisor tipping.
  33. 33. ELASTICS •Yellow(5/16”) classI or classII elastics are used for anterior retraction. •Green(5/16”) is used for posterior protraction •Blue(1/4”) or Red(3/16”) is seldom used ,only when green elastics are found in effective in low mandibular plane angle cases.
  34. 34. Essentials of Begg – Unaltered  Light orthodontic forces.  Crown tipping + Root tipping bodily movement with least taxation on anchorage.  Brackets – free tipping in initial stages.  Differential forces.  Sequence of trt. stages.
  35. 35. Essentials of Begg – Unaltered Light intra-oral elastic force. Over corrections of all displacements. Use of round high tensile wires.
  36. 36. Stage II Objectives----Common – – Maintain all corrections – in stage I. – Close all extraction spaces. Additional. – Controlled tipping – space closure – ant. retraction. – Prevent excess tipping – efficient brakes – space closure by protracting post.
  37. 37. Archwires in Stage II of Refined Begg In extn. & non extn. cases – 0.018” P or P+, or 0.020” P wires. If stage corrections involved – extreme deep bite, badly distorted arch forms or severe rotations – 0.020 archwires effective. Anchor bends PM bypassed – except when in distobuccal rotation.
  38. 38. Controlled tipping of the incisors MAA – lingual root torque – controlled lingual tipping – incisors during retraction. Lower incisors – labial root torque by MAA auxillary. Canines – excess tipping – 0.010 uprighting springs.
  39. 39. BIOMECHANICS OF MAA UPPER ARCH • Moment caused by intrusive force – crown labial, root lingual. • Moment caused by reactive force – crown lingual, root labial. • Moment produced by intrusive force counteract moment produced by reactive force. Controlled tipping occurs. • If intrusive force elastic force is inadequate, or the large, M/F ratio will be inadequate for controlled tipping.
  40. 40. • MAA causes same couple as generated by intrusive force from base arch wire i.e.. crown labial, root lingual. • Moment produced by MAA counteract moment produced by reactive force. controlled tipping occurs.
  41. 41. LOWER ARCH •MAA is used for lingual root torque may be required to prevent uncontrolled crown lingual-root labial tipping of lower incisors.
  42. 42. Braking mechanics Cases – excess space closed by post. protraction. Good profile at start of treatment. ‘Brakes’ – reverse anchorage site.
  43. 43. Braking springs: passive uprighting springs – 0.018 wire. Angulated T pins: prevent further tipping Commonly used: Braking springs: passive uprighting springs – 0.018 wire. Angulated T pins: prevent further tipping
  44. 44. Combination wires: either of SS or Alpha Ti alloy. Ant segment. – 0.022 x 0.018 (ribbon mode). Post. segment – 0.018 round . Alpha Ti – easier to engage in ant. br. slots. chance of distortion. Use SS combination wire - torque than alpha Ti. Disadvantage – expensive.
  45. 45. SS 0.022 x 0.018 sectionals – torqued in ribbon mode – piggy back over 0.018 base wire.
  46. 46. Check list • Spaces closed completely. • Anterior edge to edge bite or +ve overjet in open bite cases. • Canine & molar relations – Cl I or super Cl I
  47. 47. Conclusion  Through the use of the optimum orthodontic force ie, one that moves the teeth most rapidly, with least discomfort to the patient and with least damage to the teeth and their investing tissues, effective space closure is achieved with minimum taxation of anchorage.  Teeth are left in the proper position to be uprighted and put into good axial relation in the third stage.
  48. 48.