Segmented arch technique /certified fixed orthodontic courses by Indian dental academy
63 likes13,004 views
The document discusses the segmented arch technique (SAT) for orthodontic treatment. Some key points: - SAT involves dividing the dental arch into segments separated by gaps between teeth, allowing forces to be applied selectively to small groups of teeth. - Benefits include consolidation of teeth into functional units, varying the cross-section and force levels between segments, and prefabrication of calibrated springs. - The document outlines procedures for SAT including preliminary bracket placement, attachment selection and placement ensuring proper angulation, and space closure techniques using either segmental springs or loops. - SAT principles are discussed for correcting deep bites using intrusion mechanics or open bites using extrusion mechanics to selectively move small tooth groups.
Segmented arch technique /certified fixed orthodontic courses by Indian dental academy
- 1. SEGMENTED ARCH TECHNIQUE INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com 1
- 2. Introduction Rationale of SAT Preliminary Bracket Alignment Deep overbite correction Open bite correction Space Closure Root correction www.indiandentalacademy.com 2
- 3. Introduction: Designed to deliver light continuous forces. “continuous” arch wire. Segmented arch consists of multiple wire cross sections. SA does not connect brackets & tubes on adjacent teeth. www.indiandentalacademy.com 3
- 4. Rationale Consolidation of teeth into units: Segmentation allows the treatment to proceed by consolidation of teeth into units. Few teeth are considered for each segment. Continuous arch-forces are distributed to the adjacent teeth. www.indiandentalacademy.com 4
- 6. Rationale Varying Cross-section of Arch wire: Active units Reactive units Wires used to displace the teeth should have low LDR. www.indiandentalacademy.com 6
- 7. Increasing the Inter bracket distance: Forces used during intersegmental mechanics are applied at large distances. Continuous arch – Active & Reactive forces occur on the adjacent teeth. www.indiandentalacademy.com 7
- 8. Increases the space available for longer activations. www.indiandentalacademy.com 8
- 9. Prefabrication & Precalibration: • Continuous arch –Difficult to determine the forces. • Segmentation allows the use of precalibrated springs to deliver the desired forces. www.indiandentalacademy.com 9
- 10. Clinical Efficiency: No. of arches are made during treatment in continuous arch therapy. In segmental approach continual replacement of arch wires are not required www.indiandentalacademy.com 10
- 11. Preliminary Bracket Alignment • Initial stage of treatment. • Brackets of the teeth are ideally aligned. • Goal : Consolidated segments www.indiandentalacademy.com 11
- 12. Attachments & Placement Attachments:- Slot - 0.022 x 0.028 -Hooks, auxiliary tubes, Head gear tubes. -Cuspid bracket- 0.175 X 0.025 vertical/horizontal tube. www.indiandentalacademy.com 12
- 13. Molar attachments Lingual hinge cap (0.032 X 0.032) www.indiandentalacademy.com 13
- 14. • Attachments with 1st, 2nd, 3rd order angulations are available. • Help clinician to get good occlusion. • Second order angulations can be individualized during banding. www.indiandentalacademy.com 14
- 17. Placement of Attachments Objectives: No 2nd order steps Minimal 1st order bends All slots are parallel to the occlusal plane. Variations in the tooth position & morphology. www.indiandentalacademy.com 17
- 18. Second order level:- Criteria: -Occluso-gingival level -Angulation with respect to ‘z’ or faciolingual axis. www.indiandentalacademy.com 18
- 19. Level of attachments is established first for the posteriors. -Maxillary arch: centrals, laterals, canines,1st &2nd molars. -Mandibular arch: centrals, laterals, canines,1st &2nd molars. www.indiandentalacademy.com 19
- 20. Second order Angulation: - OPG Objectives:-Proper root dispersion, & occlusion. www.indiandentalacademy.com 20
- 21. Angulations of anterior teeth are assessed Using PA cephalograms & assessed to the treatment occlusal plane. All slots should lie in the same line & roots should have proper root dispersion. www.indiandentalacademy.com 21
- 22. First order placement: -Attachments are centered mesiodistally on the crown -Parallel to the incisal edges/buccal cusp tip. www.indiandentalacademy.com 22
- 23. Objectives of PBA:- Normalize the teeth Intrasegmentally. -Rotations, B-L positions -Occlusogingival discrepancies. -Teeth torqued. Improve the Intersegmental relationship. Improve the Intermaxillary relationship. www.indiandentalacademy.com 23
- 25. Upper horse shoe shape www.indiandentalacademy.com 25
- 26. Lingual Arch Wires: Establishing & maintaining the upper and lower arch widths. Correcting intra-arch rotations or inter-segmental rotations. A-P asymmetries. Difference in the occlusal planes. Buccolingual & M-D axial inclinations of the post. teeth. Reducing the undesirable side effects. www.indiandentalacademy.com 26
- 27. Lingual Hinge Cap -0.032 X 0.032 -Ligation of the lingual arch www.indiandentalacademy.com 27
- 28. Buccal Stabilizing Segment: -To connect the individual teeth into one unit - For Alignment -To act as stop anteriorly. -Point of connection. -0.018 TMA welded to the molar. www.indiandentalacademy.com 28
- 29. Deep Overbite Correction Differential diagnosis & Treatment plan. 3 basic ways - Intrusion of Ant. teeth Extrusion of post. teeth www.indiandentalacademy.com 29
- 30. Intermaxillary growth space Skeletal vertical dimension AB Relationship Occlusal plane cant Esthetics www.indiandentalacademy.com 30
- 34. Occlusal Plane cant desired after the treatment Esthetics www.indiandentalacademy.com 34
- 35. Principles of Anterior Intrusion -Controlling force magnitude & constancy -Anterior single point contact -Point of force application -Selective Intrusion -Control of reactive units -Avoiding Extrusive mechanics www.indiandentalacademy.com 35
- 36. Controlling force Magnitude: -Magnitude of forces used for intrusion should as low as possible. -Side Effects: Root resorption Extrusion of buccal segments www.indiandentalacademy.com 36
- 37. FORCE VALUES FOR INTRUSION TOOTH MOVEMENT FORCE (gm) INTRUSION PER SIDE 2 UPPER CENTRAL INCISORS 15 – 20 30 –40 4 UPPER INCISORS 30 – 40 60 – 80 6 UPPER ANTERIORS 60 120 2 LOWER CENTRAL INCISORS 12.5 25 4 LOWER INCISORS 25 50 6 LOWER ANTERIORS 50 100 2 UPPER CANINES 25 - 2 LOWER CANINES 25 - MOLAR EXTRUSION 60 – 100 120 – 200 www.indiandentalacademy.com TOTAL IN MIDLINE 37
- 38. Force constancy is obtained by using low LDR springs. Intrusive Arch-0.018 x 0.025 with 3mm helix www.indiandentalacademy.com 38
- 39. Anterior Single Point Contact: -Intrusion arch is not placed in the anterior brackets. -Torque -Allows the clinician to know the force systems involved. (Statically Determinant) -Anterior alignment arch wires can be placed. www.indiandentalacademy.com 39
- 40. Point of Force Application: Force applied to the Cres will not produce any labial /lingual rotation. Intrusion arch is placed anterior to the labial surface. www.indiandentalacademy.com 40
- 42. Control of the Reactive Units: -Minimization of force magnitudes. Side Effects: Plane of occlusion in the buccal segments is altered. • Forces of intrusion should be kept low. • More no.of teeth should be incorporated. • Retraction is done initially. • Occipital HG www.indiandentalacademy.com 42
- 44. • Equal & opposite extrusive effect www.indiandentalacademy.com 44
- 45. Avoiding Extrusive Mechanics: -CL-II elastics -CL-III elastics -Cervical HG Pts requiring true intrusion. www.indiandentalacademy.com 45
- 46. Principles of Anterior Intrusion Use of optimal magnitudes of force Point contact in the anterior region Selection of the point of force application with respect to the Cres. Selective intrusion Control over the reactive units Avoidance of undesirable eruptive mechanics. www.indiandentalacademy.com 46
- 47. Continuous Intrusion Arch • • • Post.Anchorage unit Ant.segment Intrusion arch(0.017x0.025 TMA). 0.018 round TMA stops are welded – to serve as tie backs. www.indiandentalacademy.com 47
- 48. Three-Piece Intrusion Arch Intrude the flared incisors, control their axial inclinations & retract with good anchorage control. Point contact of force application. Pt’s with proclined incisors have to be treated differently. www.indiandentalacademy.com 48
- 50. Post-Anchorage unit Ant.segment with a posterior extension Intrusion cantilevers Chain elastic. www.indiandentalacademy.com 50
- 51. Distal extensions end 2-3mm distal to the Cres of he anterior segment. Design of the appliance -low friction. www.indiandentalacademy.com 51
- 52. Anterior Segment & Direction of Intrusive force www.indiandentalacademy.com 52
- 54. CANINE INTRUSION: A cantilever from the auxiliary tube of the molar tied to the canine bracket. The cantilever is bent to the lingual to give a lingual force. www.indiandentalacademy.com 54
- 56. Extrusion of Posterior Segments Higher forces promote posterior eruption. Canting of the occlusal plane should be avoided. Extrusion arch is similar to the intrusion arch. Eruptive appliances should be used in growing children. Extrusion occurs rapidly than intrusion. www.indiandentalacademy.com 56
- 57. 2 types of extrusion can be achieved with extrusion arch. Type-I Combines extrusion with rotation of the buccal segment. Applied in the lower arch. Type-II Used in the upper arch when parallel eruption of buccal segments is required www.indiandentalacademy.com 57
- 59. Types of extrusive mechanics • • • Tip-back mechanism Base arch mechanism Parallel eruption of buccal segments www.indiandentalacademy.com 59
- 60. Tip back mechanism:Indications: Growing pt with a forward rotation. Deep curve of spee in the lower arch. Arch length inadequacy. www.indiandentalacademy.com 60
- 61. Tip back mechanism consists: 0.036 inch lingual arch 0.018x0.025 anterior segment Buccal stabilizing segment of 0.018x0.025. 0.018x0.025 tip back spring www.indiandentalacademy.com 61
- 62. CRot is placed around the root of the 2nd molar. Eruption & rotation of buccal segments. Increase in the arch length www.indiandentalacademy.com 62
- 63. Base Arch Mechanism: Also called as Intrusive arch. Buccal and anterior arch wires are identical. 0.018x0.025 SS www.indiandentalacademy.com 63
- 64. Ligature is tied to the helices to prevent flaring of anterior teeth. • Effects: -Eruption & rotation of the buccal segments. -Roots of the buccal segments move forward. -No increase in the arch length. • www.indiandentalacademy.com 64
- 65. Parallel Eruption of the Buccal Segment: Used in the upper jaw Cervical HG with long outer bow . www.indiandentalacademy.com 65
- 67. Natural plane of occlusion must be monitored 0.018x0.025 wire is placed as an indicator wire. www.indiandentalacademy.com 67
- 68. Closing Anterior Open Bite : Extrusion Arch Open bites occur less frequently. Treatment involves a wide variety of approaches. Dental compensations – Vertical elastics. Extrusion Arch: reverse action of the intrusion arch. Effective way to close the open bite without Pt compliance Choice of dental compensation is based on lip-tooth distance. www.indiandentalacademy.com 68
- 69. Extrusion Arch Action at the Molar:- www.indiandentalacademy.com 69
- 70. Extrusion Arch Timing: Undesirable actions at the molars will be insignificant if the EA is kept only for a minimum time. (Isaacson) Segment of SS wire has to be placed in the posterior segment. www.indiandentalacademy.com 70
- 71. Extrusion Arch Action at the Incisor:- Extrusion -Single tooth -Groups of teeth. • Magnitude of extrusive forces used are100gms for 4 incisors • 0.016X0.022 SS wire is used www.indiandentalacademy.com 71
- 72. Space Closure Biomechanical Basis of extraction space closure 2 methods to close extraction sites -Segmental springs -Loops in the continuous wire www.indiandentalacademy.com 72
- 74. Single cuspid retraction Vs En-mass retraction Adequately designed appliances based on the desired biomechanics. En-mass space closure reduces the treatment time. Separate canine retraction is done in anterior crowding cases. www.indiandentalacademy.com 74
- 75. Space closure –A Biomechanical Perspective www.indiandentalacademy.com 75
- 76. Force systems for Grp B space Closure. M/F-10/1 is needed for Translation. www.indiandentalacademy.com 76
- 77. Space closure –A Biomechanical Perspective Grp-A anchorage: Mesial force on the posterior teeth should be minimized. -Forces & moments acting on the posterior teeth can be minimized by using extraoral force. www.indiandentalacademy.com 77
- 78. Space closure –A Biomechanical Perspective Differential tooth movement: www.indiandentalacademy.com 78
- 79. Grp-A anchorage: Space closure with differential moments. Increasing the posterior M/F ratio encourages root movement & decreasing the M/F ratio causes tipping type of tooth movement. Magnitude of the vertical force – difference between anterior & posterior moments. www.indiandentalacademy.com 79
- 80. Determinants of space closure: Amount of crowding Anchorage Axial inclination of canines & incisors. Midline discrepancies & Lft/Rht symmetry Vertical dimension www.indiandentalacademy.com 80
- 81. Space closure Considerations for anchorage control & Differential tooth movement Size of the Anchorage units No. of teeth . Differential force systems-Variable moments & Forces -Forces act in 3 planes of space. www.indiandentalacademy.com 81
- 82. Segmental En-mass Extraction space closure • • • • T-loop space closure springs are used Principle of SA-Ant & Post units are considered as one large tooth. Rt & Lft buccal segments are connected by TPA. Design uses 0.0175x0.025 TMA wire. www.indiandentalacademy.com 82
- 84. General Concepts for Segmented T-loop use Passive form of a spring Activation of the spring requires application of forces & moments. Neutral position –Only moments are applied. www.indiandentalacademy.com 84
- 85. General Concepts for Segmented T-loop use Differential Anchorage: Unequal α & β moments. Higher moment is applied to the anchor teeth. Differential moments –Off-centered V-bend. Centering the T-loop -produces equal & opposite moments. www.indiandentalacademy.com 85
- 86. Symmetric Space Closure – Grp B Anchorage Simplest form of space closure. Equal translation of Ant & Post segments. T-loop centered Distance =Interbracket Distance - Activation 2 www.indiandentalacademy.com 86
- 87. Space closure is monitored periodically. -amount of remaining space -axial inclinations www.indiandentalacademy.com 87
- 88. Space Closure – Grp A Anchorage • T-loop is positioned closer to the post. Attachment. www.indiandentalacademy.com 88
- 89. Space Closure – Grp C Anchorage Post. Protraction is the difficult space closure. Extrusive effect on the anterior teeth. CL-III elastics – to augment the protraction www.indiandentalacademy.com 89
- 90. Separate Canine & Incisor Retraction Anterior crowding Midline disrepancies Moment is produced on the canine during separate canine retraction. www.indiandentalacademy.com 90
- 91. 3 ways to counteract this moment: www.indiandentalacademy.com 91
- 95. Cuspid-Cuspid Bypass wire: Prevent Rotation Alter arch width Eliminate side effects from vertical forces. 0.017 X 0.025SS www.indiandentalacademy.com 95
- 98. Canine & Incisor Root Movement Control of axial inclinations of teeth is important. Good axial inclination & root parallelism-stable result. Root correction involves-Individual/Groups of teeth. Enmass root movement Separate canine root following separate canine retraction. Separate incisor root correction www.indiandentalacademy.com 98
- 99. Diagnosis & Evaluation of root correction Clinically-Inclination of canine & incisor brackets. Lateral films-Axial inclinations www.indiandentalacademy.com 99
- 100. Enmass Root Movement Second phase of space closure after tipping movement. Moments are delivered by Root springs. Moments generated cause the crowns to flare and roots to retract. Ligature tie –to prevent the space from opening. www.indiandentalacademy.com 100
- 101. Selection of wire in the anterior segment: • • Rigid wire placed in the 6 anterior teeth. Undersized wire – rotation of the incisors. 3 major root springs for enmass root movement www.indiandentalacademy.com 101
- 105. Incisor root movement: 0.021 x 0.025 TMA root spring www.indiandentalacademy.com 105
- 106. References:Biomechanics In Orthodontics – Marcotte. Biomechanics In Clinical Orthodontics-Ravindra Nanda. Rationale of the Segmented arch –Burstone AJO (1962). Deep overbite correction by intrusion – Burstone AJO(1977). Biomechanics of Deep Overbite Correction-Burstone (Semin Orthod 2001). www.indiandentalacademy.com 106
- 107. Segmented approach to simultaneous intrusion and space closure: Biomechanics of the three-piece base arch appliance-Bhavna Shroff AJODO-1995. Closing Anterior Open bite :The Extrusion Arch – Isaacson & Lindau Semin Orthod 2001. The Segmented arch approach to space closure – Burstone 1982 AJO www.indiandentalacademy.com 107
- 108. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com 108