Action and reaction _ Dr. Nabil Al-Zubair


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Action and reaction _ Dr. Nabil Al-Zubair

  1. 1. and Reaction Dr. Nabil Al-Zubair
  2. 2. and Reaction Dr. Nabil Al-Zubair
  3. 3. MECHANICSIntroduction Success in an orthodontic treatment Two factors must be combined A good treatment plan Excellent biomechanics called Describes the effect of: forces on objects (teeth and bone) Contemplated within a part of Engineering
  4. 4. ‫شرح‬‫آليات‬‫أجهزة‬ ‫عمل‬‫لحركة‬ ‫المستخدمة‬ ‫القوة‬ ‫ونظام‬ ‫األسنان‬ ‫تقويم‬‫األسنان‬ Biomechanics the part of Mechanics that: studies movement in relation with biological systems Biomechanical principles Explain The mechanisms of action of the orthodontic appliances Force system utilized for dental movement ‫الحركة‬‫في‬‫النظم‬‫البيولوجية‬ ‫الميكانيكا‬‫الحيوية‬
  5. 5. for Greater Benefit of the patient Whoever gets to understand HOW these physics principles work will be able to: Design Select Use ‫كل‬‫من‬‫يفهم‬‫هذه‬ ‫عمل‬ ‫كيفية‬‫المبادئ‬ Orthodontic Appliances
  6. 6. Laws of Newton
  7. 7. The law of inertia: The law of acceleration The law of action and reaction ‫قانون‬‫الذاتي‬ ‫القصور‬ ‫قانون‬‫التسارع‬ ‫قانون‬‫الفعل‬ ‫ورد‬ ‫الفعل‬ The three laws of motion In 1686, Newton presented the fundamental laws of Mechanics The three laws of motion are the following:
  8. 8. The law of inertia ‫قانون‬‫الذاتي‬ ‫القصور‬
  9. 9. Forces must be applied in order to obtain movement A dental malposition can never resolve itself spontaneously because of this In orthodontics Teeth tend to remain almost motionless unless A force applied to provoke tooth displacement
  10. 10. The larger the force that has to be exerted to produce physiologic movement In orthodontics Tooth that we want to move Said in another way we can affirm that Teeth move in the direction of the applied force The larger the Root Volume ‫تتحرك‬‫القوة‬ ‫اتجاه‬ ‫في‬ ‫األسنان‬‫المطبقة‬ Diverse forces with Different intensities we can apply Depends on
  11. 11. To every action there is always opposing and equal reaction) The law of action and reaction:
  12. 12. to minimize or eliminate: 1. Therapy efficiency can improve; thus, 2. Rapid and painless treatments with negligible damage to teeth and supporting tissues can be achieved with 3. Less collateral damage and 4. More pleasing and durable results These three laws offer evident benefits to the orthodontist and the patient If applied in a appropriate manner The "SECRET“ in orthodontics is : secondary or collateral effects of treatment ‫إذا‬‫مناسبة‬ ‫بطريقة‬ ‫طبقت‬
  13. 13. :‫األسنان‬ ‫تقويم‬–‫وفن‬ ‫علم‬ ‫مغيط‬ ‫تغيير‬ ‫مش‬
  14. 14. Exact treatment Orthodontic Appliances Pharmaceuticals have a similar FUNCTION Accurate DIAGNOSIS to be able to define
  15. 15. Pharmaceuticals In medicine, the physician makes a diagnosis and then selects the proper medication to accomplish his goals In pharmacology, medicines are used to act upon cells, tissues and specific organs The collateral effects of medicines are unavoidable and must be well managed
  16. 16. Orthodontic appliances In orthodontics, the orthodontist must make his diagnosis and then select the best appliance design to reach his objectives In orthodontics moments and forces are used to act upon cells and specific tissue that support teeth and bone Secondary effects are also produced during tooth movement and should also be recognized and managed with care. When such effects are known beforehand, precaution measures can be taken to counter these harmful effects, which in some instances can be managed to our benefit
  17. 17. Pharmaceuticals Orthodontic appliances Finally, in orthodontic appliances as in medicine the efficiency depends upon the degree of cooperation of the patient
  18. 18. What is force? What is the center of resistance? What is the Center of Rotation? What is a moment?
  19. 19. What is force? = they are Actions applied to bodies (wire, coil, elastic, etc.) over another body (teeth or bone) = in clinical orthodontics its unit is Grams Ig=0.00981N, or IN=101.937 g
  20. 20. - every free body has a point known as Mass Center What is the center of resistance? - The center of resistance is the point a force has to pass through - in order to move an object freely in a linear manner Said in another way, - every time that the line of action of a force passes through mass center of a free body therefore - will suffer a translation movement
  21. 21. - Any force that acts through the center of resistance of a tooth makes it translate in a bodily manner - A tooth in the mouth is not a free body because periodontal support tissue does not let it move freely The center of resistance equivalent to The mass center for free bodies
  22. 22. - Level of support of the alveolar bone The center of resistance of a tooth depends on - Length and morphology of the root, - Number of roots
  23. 23. The center of resistance Single root tooth between the middle and cervical third part of the root Multiple root tooth At one or two millimeters apical from the furcate
  24. 24. - to produce pure dental translation Because braces can only be bonded on the crowns of teeth, there are very few opportunities in which it is possible to apply a force that can act through the center of resistance of the tooth
  25. 25. - The center of rotation can be very close What is the Center of Rotation? - Arbitrary point located at a distance from the center of resistance on which a tooth is going to turn around if a force is applied - but it will never coincide with the center of resistance
  26. 26. Rotation or first order dental movement (in-out movement) along the larger axis of the tooth Angulation or second order dental movement (Tip) around the mesiodistal axis Torque or third order movement around the buccolingual axis In orthodontics
  27. 27. What is a moment? a force applied on a brace that does not act through the center of resistance provokes the rotation of the tooth - said in another way, ‫العزم‬=‫القوة‬‫ذراعها‬ ‫في‬
  28. 28. Dental movement physiology Dental movement A biological response to the physiologic reaction toward forces ‫استجابة‬‫لرد‬ ‫بيولوجية‬‫فسيولوجي‬ ‫فعل‬
  29. 29. This union is done by the periodontal insertion represented by: - Dental cement - Periodontal ligament and - Alveolar bone Maxillary bonesTeeth united to Dentoalveolar Joint
  30. 30. - intermingling with: - blood vessels - cellular elements - nerve endings and - interstitial fluids The periodontal ligament = occupies a space of approximately 0.5 mm (between the alveolar wall and the tooth cement) = it is responsible for the dental joint = Made out of collagen fibers that insert themselves in the root cement and in the alveolar bone
  31. 31. Tooth movementForce Tooth PDL/Bone Biological electricity Blood flow Microfractures Osteoblasts (tension) Osteoclasts (compression) Resorption and Deposition of bone Dental movement begins two days after the force is applied alveolus dislocates in the direction of the applied force, with orthodontic movement as a consequence
  32. 32. 4. Rotation Types of dental movement Dental movement can be classified in many ways: 1. Inclination a. Uncontroled inclination b. Controlled inclination 2. Translation 3. Root displacement
  33. 33. a. Uncontrolled inclination: b. Controlled inclination: Center of rotation Slightly apical to center of resistsnce Apex of root Wire ROUND arch wire Rectangular Arch Wires This type of inclination happens when - This movement can be obtained by any orthodontist, but is usually not wanted - This is a wanted movement
  34. 34. - with the use of Elastomeric Power Chains in order to close spaces This uncontrolled inclination happens when we have - ROUND arch wire in the slot of the brace and force is applied to the tooth
  35. 35. - a MOMENT is produced and this provokes both teeth to rotate over their center of rotation Uncontrolled inclination of the incisors - with Elastomeric Power Chain on a round arch wire during space closure - The force is placed on the crown, and because there is - no other force to counter react,
  36. 36. - This happens because the force is applied on the crown away from the center of resistance When an Elastomeric Power Chain is placed from a molar to a canine, with a round arch, Inclination (moment) of the crowns toward the space the roots will become completely divergent the outcome is :
  37. 37. b. Controlled inclination: it is obtained with the application of: to move the crown A force in order to: control or maintain the position of the root apex the placement of A moment
  38. 38. - It counteracts (torque) part of the moment caused by the dental retraction b. Controlled inclination: - to retract the anterior sector without moving the location of the tooth apex An Example of this inclination when we want Rectangular Arch Wires obtained with When we softly insert the wire in the slot of the brace
  39. 39. 2. Translation: the anatomical characteristics that surround teeth - Is one of the most difficult movements in orthodontics The application of a force through the center of resistance very difficult Make This is caused by:
  40. 40. - in-mass or bodily movement the line of action of a force passes through the center of resistance of the tooth It is also known as Happens when - This is only possible when: • crown • apex - horintzoally displaced
  41. 41. - We obtain this type of movement with the use of power arms: allow the line of action of the force to pass directly through the center of resistance
  42. 42. - Root displacement is commonly used: - to torque incisors - to upright canine roots after space closure - upright posterior teeth that are mesially inclined, etc. 3. Root displacement: - In this movement: - Moment and a force are applied to displace only the root, - meanwhile the crown is NOT displaced
  43. 43. produce a pure rotation around the longitudinal axis of the tooth (seen from the occlusal view) 4. Rotation: To make this movement: a couple or coplanar forces are required
  44. 44. In this case the tooth maintains its position because - both forces annul each other since both lines of force act at a same distance perpendicular to the center of resistance, - leaving only the pure Moment (pure rotation) What is a couple? Two parallel forces of the same magnitude but in opposite directions
  45. 45. Select, apply and control in an efficient manner the force systems that will be utilized. Clearly understanding the basic concepts of orthodontic biomechanics the physiology of dental movement Analyze the different actions and reactions that can happen during the different stages of orthodontic treatment
  46. 46. ACTION AND REACTION The third law of Newton applies in almost all orthodontic movements - Sometimes the reaction to a movement results in an unwanted movement
  47. 47. 1. Align intruded or extruded teeth, - where the same force produced to make these movements will be applied on the surrounding teeth provoking a movement in opposite direction to the one we want to produce. Example of the third law of newton
  48. 48. 2. distalize a molar with NiTi open coils - The molar distalization is accomplished, but the same force applied backwards to distalize is applied on the buccal segment, not only provoking distalization and molar tipping, but also proclination of the buccal segment
  49. 49. 3. The action of a bend put it in a passive manner in the slots of two braces activate the wire, placing it in the slots to determine the direction of a movement predict the direction of the movement to take place
  50. 50. put it in a passive manner in the slots of two activate the wire, placing it in the slots to determine the direction of a movement predict the direction of the movement to take place
  51. 51. Where to place the bend Far from the center of the arch wire Center of the arch wire two segments: a short one and a long one Equal forces in different directions The greater moment : the side that receives the shorter segment of the bend the forces cancel one another Equal moments oppose each other Different moments take place with
  53. 53. Deep bite correction with a tip back Spee curve leveling with reverse curves Correction of a bilateral posterior open bite with reverse curves Correction of a deep bite with a bite plane and bilateral box elastics Correction of an anterior open bite with the use of a bite block (Posterior bite block) Correction of an anterior cross bite with the use of a forward arch wire Diastema closure with closing loops Root uprighting
  54. 54. Deep bite one of the most common malocclusion seen in children as well as adults
  55. 55. one of the most deleterious malocclusion of the future health of: - the masticatory apparatus and - the dental units when considered ‫مؤذ‬ from the viewpoint It is said to be
  56. 56. 1. Intrusion of upper and or lower incisors 2. Extrusion of upper and or lower posterior teeth 3. A combination of anterior intrusion and posterior extrusion 4. Proclination of incisors 5. Adult surgery Treatment modalities include:
  57. 57. Technique Removable appliance  The anterior bite plane  Headgear  Functional appliance Fixed appliance • Fixed orthodontic appliances Orthognathic surgery  Mandibular advancement  Lower labial segment setdown Restorative treatment  Restoration of the posterior occlusal vertical dimension  Occlusal splints  Dahl appliance Methods of reducing a deep overbite
  58. 58. - the large segment directs itself to the apical portion of the anterior zone Deep bite correction - If we utilize the tip back bend for the correction of a deep bite with a tip back when the short segment of the bend is inserted in the molar tube, - it can clearly be seen that: (before being inserted in the slots of the braces of the incisors) Intrusion Arch
  59. 59. Intrusive Force : Extrusive Force: anterior zone posterior zone This way
  60. 60. - with the placement of bends is that: Another consideration that we have to mind Short segment Anchorage side represent Long segment no anchorage - Moment at the molar level is greater than the one that is being produced at the incisor level This is due to the fact that making the molar much more resistant to movement
  61. 61. - When the arch wire is activated by placing it in the slots of the incisor braces at molar level at the incisor level Two moments are going to be produced Provoking a differential torque on both teeth  A mesial root movement  a distal crown movement the moment is going to be lower, taking the incisor to a more buccal position Passes buccal to the center of resistance since intrusive force
  62. 62. 1. Molar extrusion. 2. Incisor intrusion. 3. Distal inclination of the molar crowns. 4. Mesial inclination of the molar roots. 5. Buccal movement of the incisors. 6, Increase of dental arch length. 7. Posterior anchorage. 1. Apically directed Tip back Action taken Produced reaction
  63. 63. Class I molar relationship Correct crown angulation Correct crown inclination No rotation No spaces Flat to slight curve of spee Andrews 6 keys of Normal Occlusion(1972)
  64. 64. Spee curve leveling Deep curve of Spee
  65. 65. - When we use Reverse Curves to level a deep curve of Spee Intrusive Forces exercised in the posterior sectors we find - with balanced with Extrusive Forces premolar region anterior sectors Intrusive Forces
  66. 66. a positive torque - a distal inclination of the crowns - a mesial movement of their roots Another effect is intrusive forces at the molar level at the incisor level - buccal movement (positive torque) provoke
  67. 67. 1. LeveIingof the deep Spee curve. 2. Overbite reduction. 3. Extrusion of the premolar sector. 4. Intrusion of the molar and the incisors. 5. Positive torque in molars and incisors. 6. Distal inclination of the crown and mesial inclination of the roots. 7. Increase in length in the lower dental arch. 1. Use of an inverse curve in the inferior arch Action taken Produced reaction
  68. 68. Correction of a bilateral posterior open bite with reverse curves
  69. 69. - The reactions that are produced at molar, premolar and incisor levels are the same in the upper and lower dental arches far from solving the problem we can COMPLICATE it even more - Same one that we use for the leveling of a deep Spee curve We simply have to know how to place the reverse curves in order to have the desired effect The action principle of the curves On the contrary, if we do not place the curves correctly,
  70. 70. 1. Intrusion of upper and lower molars and incisors. 2. Extrusion on the upper and lower premolar sector in order to level the dental arches. 3. Increase in length in both dental arches. 4. Distal inclination of the crowns and mesial inclination of the roots in both dental arches. 5. Positive torque in molars. 6. Positive torque at upper and lower incisor level. 1. Use of curves on both dental arches Action taken Produced reaction
  71. 71. Correction of a deep bite with a bite plane and bilateral box elastics a very simple, practical and stable solution for this malocclusion - The use of an Anterior Bite Plane
  72. 72. - increase in the vertical dimension in the lower third of the face - Put a top on the anterior sector producing a posterior disclusion the use of bilateral box elastics This way, - With the bite plane we seek to: in a passive way stimulated or it can be accelerated with Extrusion of molars and premolars There will also be an
  73. 73. 1. Intrusion of inferior incisors 2. Extrusion of canines, premolars and molars due to the disclusion provoked by the bite plane 3. Improvement of the interincisal relation 1. Use of an anterior bite plane 2. Use of intermaxillary box elastics Action taken Produced reaction
  74. 74. Correction of an anterior open bite with the use of a bite block (Posterior bite block) Intrusion of the anterior sector - Anterior open bite is caused in the majority of cases by: Extrusion of the posterior sector
  75. 75. the pressure of occlusion over the bite block The purpose of the use of the bite block is: Intrusion of the posterior segment resulting in Auto rotation of the mandible producing the satisfactory closure of the open bite lack of dental contact in this zone Posterior intrusion produced by Anterior extrusion
  76. 76. we can help ourselves with the use of intermaxillary elastics to facilitate bite closure For closure of the anterior bite with a bite block
  77. 77. 1. Molar and premolar intrusion 2. Extrusion of the anterosuperior sector 3. Shortening of the inferior facial height 4. Overbite correction S. Mandible auto rotation 1. Bite block placement for open bite closure Action taken Produced reaction
  78. 78. Correction of an anterior cross bite
  79. 79. Correction of an anterior cross bite Dentoalveolar Component not a Skeletal one with the use of a forward arch wire this should only have:
  80. 80. leaving 2 mm or 3 mm of SEPARATION between the arch wire and the slot of the anterior braces - Anterior proclination - Provoke a mild molar distalization The forward arch is made by doing two small stops at the entrance of the molar tubes This arch wire going to produce
  81. 81. 1. Proclination of the upper incisors 2. Upper molar distalization 3. Positive torque in the upper incisors 4. Distal inclination of the crown and mesial inclination of the roots of the upper molars 5. Posterior anchorage 6. Reduction of the nasolabial angle 1. Placement of a forward archAction taken Produced reaction
  82. 82. 1. The forces cancel each other. 2. Root up righting by the action of the Moments 1. "V" second order bends to upright divergent roots Action taken Produced reaction Root uprighting must be made on (a stainless steel arch, round or rectangular)
  83. 83. making these move bodily without any Moment that may make them rotate Diastema closure with closing loops A diastema is defined as a space between two teeth these can be treated with: orthodontics or with cosmetic dentistry The orthodontist must determine the cause of it before designing an appliance to correct it Usually closing loops are: going to exert their forces in a perpendicular mode to the center of resistance of the tooth
  84. 84. l. Closure of the diastema with a bodily movement Produced reaction l. Placement of a vertical closure loop Produced result
  85. 85. Any Questions?
  86. 86.
  87. 87. Thank you for listening! Dr. Nabil Al-Zubair