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Retraction mechanics in swa 2 /certified fixed orthodontic courses by Indian dental academy
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Retraction mechanics in swa 2 /certified fixed orthodontic courses by Indian dental academy

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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 www.indiandentalacademy.com ,or call
0091-9248678078

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Retraction mechanics in swa 2 /certified fixed orthodontic courses by Indian dental academy Retraction mechanics in swa 2 /certified fixed orthodontic courses by Indian dental academy Presentation Transcript

  • INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
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  • Contents Introduction Anchorage Optimum force Retraction mechanics •Sliding mechanics •Loop mechanics •Biomechanical advances Conclusion www.indiandentalacademy.com
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  • ANCHORAGE IN ORTHODONTICS NEWTON’S third law of motion : “ Every action has an equal and opposite reaction.” www.indiandentalacademy.com
  • DEFINITIONS : Moyers :  “ Resistance to displacement.”  Active elements and reactive elements. T.M. Graber :  “The nature and degree of resistance to displacement offered by an anatomic unit when used for the purpose of effecting tooth movement.” www.indiandentalacademy.com
  • DEFINITIONS : Proffit :  “Resistance to unwanted tooth movement.”  “Resistance to reaction forces that is provided (usually) by other teeth, or (sometimes) by the palate, head or neck (via extraoral force), or implants in bone.” www.indiandentalacademy.com
  • DEFINITIONS : Nanda :  “The amount of movement of posterior teeth (molars, premolars) to close the extraction space in order to achieve selected treatment goals.” www.indiandentalacademy.com
  • DEFINITIONS : BENNETT AND MCLAUGHLIN: Anchorage control: ‘The manoeuvres used to restrict undesirable changes during the opening phase of treatment, so that leveling and aligning is achieved without key features of the malocclusion becoming worse.’ www.indiandentalacademy.com
  • CLASSIFICATION: Moyers :  According to the manner of force application: 1. Simple anchorage : Resistance to tipping. 2. Stationary anchorage : Resistance to bodily movement. www.indiandentalacademy.com
  • CLASSIFICATIONS: 3. Reciprocal anchorage : Two or more teeth moving in opposite directions and pitted against each other by the appliance. www.indiandentalacademy.com
  • CLASSIFICATIONS: Moyers :  According to the jaws involved: 1. Intra maxillary : Anchorage established in the same jaw. www.indiandentalacademy.com
  • CLASSIFICATIONS: 2. Inter maxillary : Anchorage distributed to both jaws. Baker’s anchorage (1904) www.indiandentalacademy.com
  • CLASSIFICATIONS: Moyers :  According to the site of anchorage: 1. Intra oral : Anchorage established within the mouth. www.indiandentalacademy.com
  • CLASSIFICATIONS: 2. Extra oral : Anchorage obtained outside the oral cavity. a.) Cervical : eg. neck straps b.) Occipital : eg. Head gears c.) Cranial : eg. High pull headgears d.) Facial : eg. Face masks www.indiandentalacademy.com
  • CLASSIFICATIONS: www.indiandentalacademy.com
  • CLASSIFICATIONS: 3. Muscular : Anchorage derived from action of muscles. eg. Vestibular shields. www.indiandentalacademy.com
  • CLASSIFICATIONS: Moyers :  According to the number of anchorage units : 1. Single or primary anchorage: Anchorage involving only one tooth. 2. Compound anchorage: Anchorage involving two or more teeth. www.indiandentalacademy.com
  • CLASSIFICATIONS: 3. Reinforced anchorage: Addition of non dental anchorage sites. eg. Mucosa, muscle, head, etc. www.indiandentalacademy.com
  • CLASSIFICATIONS: Nanda :  A anchorage : critical / severe 75 % or more of the extraction space is needed for anterior retraction.  B anchorage : moderate Relatively symmetric space closure (50%)  C anchorage : mild / non critical 75% or more of space closure by mesial movement of posterior teeth www.indiandentalacademy.com
  • CLASSIFICATIONS: www.indiandentalacademy.com
  • CLASSIFICATIONS: Burstone :    Group A arches Group B arches Group C arches www.indiandentalacademy.com
  • CLASSIFICATIONS: www.indiandentalacademy.com
  • BIOLOGICAL ASPECTS OF ANCHORAGE : Factors affecting anchorage:    Number of roots Shape, size and length of each root multirooted > single rooted longer rooted > shorter rooted triangular shaped root > conical or ovoid root larger surface area > smaller surface area www.indiandentalacademy.com
  • BIOLOGICAL ASPECTS OF ANCHORAGE : Factors affecting anchorage:  Cortical anchorage: Cortical bone vs. medullary bone  Muscular forces: Horizontal growers vs. vertical growers www.indiandentalacademy.com
  • OPTIMUM FORCE  Pressure in the PDL= Force applied to a tooth Area of distribution in PDL  Tooth movement increases as pressure increases upto a point, remains at same level over a broad range and then may gradually decline with extremely heavy pressure.  Anchorage control : Concentration of desired force and dissipation of www.indiandentalacademy.com
  •  PRESSURE RESPONSE CURVE : www.indiandentalacademy.com
  • BIOLOGICAL ASPECTS OF ANCHORAGE : Anchorage situations :  Differential effect of very large forces: More movement of arch segment with the larger PDL area. Questionable response. www.indiandentalacademy.com
  • MECHANICAL ASPECTS OF ANCHORAGE :  Tooth movement is brought about after overcoming the frictional resistance during sliding of wire in the bracket.  Frictional force is proportional to the force with which the contacting surfaces are pressed together  Affected by the nature of the surface  Independent of the area of contact www.indiandentalacademy.com
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  • Orthodontic space closure should be individually tailored based on the diagnosis and treatment plan. www.indiandentalacademy.com
  • Two Schools of Thought for retraction of anteriors following Premolar extraction Separate canine and anterior retraction En-mass retraction www.indiandentalacademy.com
  • First School of Thought www.indiandentalacademy.com
  • First School of Thought www.indiandentalacademy.com
  • First School of Thought www.indiandentalacademy.com
  • Second School of Thought www.indiandentalacademy.com
  • Second School of Thought www.indiandentalacademy.com
  •  Storey, Smith and Stuwed have show that : 5-55% of the total extraction space can be taken up by the anchor molar.  According to Salzman during space closure following extraction some amount of anchor loss will definitely take place. www.indiandentalacademy.com
  •  Begg stated that a differential force application (reciprocal light force) moves the anterior teeth while posterior teeth remain stationery. www.indiandentalacademy.com
  • RETRACTION MECHANICS FRICTION CONTINUOUS FRICTIONLESS SEGMENTAL CONTINUOUS www.indiandentalacademy.com SEGMENTAL
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  • Components Affecting Sliding Mechanics 1. WIRE MATERIAL: cobalt chromium, beta titanium and nickel titanium wires produces more friction than stainless steel wires. 2. WIRE CROSS SECTION: rectangular wire produces more friction than round wires. www.indiandentalacademy.com
  • 3. WIRE DIMENSIONS: larger diameter wires produces more friction than smaller 4. BRACKET COMPOSITION: The composition of bracket eg., ceramic brackets, causes more friction than the stainless steel bracket. www.indiandentalacademy.com
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  • Which slot? 18 or 22 www.indiandentalacademy.com
  • Which wire in which slot? www.indiandentalacademy.com
  • Position of hooks: Turk et al in 2005 CRe dependent on: Bone support Root morphology Incisor inclination www.indiandentalacademy.com
  • Ligation techniques: Steel or elastomeric ligatures Or self ligating bracket www.indiandentalacademy.com
  • Edwards et al in 1995 compared four ligation techniques Similar results- Spiller et al and Bazakidau also. Berger JL in 1990 compared Speed bracket with conventional ligation www.indiandentalacademy.com
  • Type of force: 1. active tieback 2. power chain 3. niti close coil spring 4. screw type mechanism www.indiandentalacademy.com
  • Active tiebacks www.indiandentalacademy.com
  • Type one tieback. Active tie-backs consist of an elastic module and ligature tie combination. www.indiandentalacademy.com
  • Type Two tieback. 2 Active tie-backs consist of an elastic module and ligature tie combination. www.indiandentalacademy.com
  • Amount of force given by the module Prestreching www.indiandentalacademy.com
  • Elastic chain www.indiandentalacademy.com
  • Pletcher coil spring www.indiandentalacademy.com
  • Niti coil springs www.indiandentalacademy.com
  • Hycon www.indiandentalacademy.com
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  • O brien et al in 2002 did a RCT to compare 3 methods of space closure: 1.Active tiebacks- 0.35mm/month 2.Powerchain – 0.58mm/month 3.Niti coil spring- 0.81mm/month www.indiandentalacademy.com
  • Anchorage : 1.Band second molars 2.Headgear 3.Curve of spee in the stainless steel wire 4.TPA ????? 5.Implants www.indiandentalacademy.com
  • Wise et al in 1994 Bobak V et al in 1997 www.indiandentalacademy.com
  • Implants Placement of maxillary microscrew. www.indiandentalacademy.com Mandibular microscrew.
  • Initial maxillary canine retraction force applied with tieback between micro-implant & canine. After 2 months of treatment, maxillary anterior retraction force applied with nickel titanium coil spring. www.indiandentalacademy.com
  • Sliding mechanics Enmass cuspid followed by anteriors www.indiandentalacademy.com
  • CANINE RETRACTION WITH SLIDING MECHANICS www.indiandentalacademy.com
  • CANINE RETRACTION Minor Cuspid Retraction Uncontrolled tipping of 1-2 mm www.indiandentalacademy.com Major cuspid retraction Controlled tipping or translation of more than 3 mm.
  • Minor Cuspid Retraction Minor Cuspid Retraction :- uncontrolled tipping of the canine, when 1-2mm of arch length per side is required. It can be carried out with the use of lace backs. www.indiandentalacademy.com
  •  Bennett and McLaughlin introduced lacebacks to prevent forward tipping of canine during levelling and aligning  These are constructed using 0.009” or 0.010” ligature wire, tied in figure-ofeight fashion. www.indiandentalacademy.com
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  • Major cuspid retraction  Controlled tipping or translation of more than 3 mm of arch length per side is required.  Where the canine’s axial inclination is ideal, it is preferable to translate the tooth.  As the canine is retracted, the anterior crowding unravels. The lateral incisors tends to move distally due to pull of the trans-septal fibers. www.indiandentalacademy.com
  • MOMENT www.indiandentalacademy.com MOMENT
  • COUNTER MOMENT MOMENT www.indiandentalacademy.com MOMENT COUNTER MOMENT
  • Process is repeated until tooth is retracted or the elastic force is dissipated www.indiandentalacademy.com
  • INCISOR RETRACTION MECHANICS www.indiandentalacademy.com
  • INCISOR RETRACTION (SLIDING MECHANICS)  In friction or sliding mechanics an elastic chain or thread is attached to the tooth and a continuous archwire is placed.  The elastic chain is the force component of the retraction.  The wire-bracket interaction produces the moment www.indiandentalacademy.com
  • Advantages of Friction Mechanics  The complicated wire bending is not     required, making initial wire placement less time-consuming. This can enhance patient comfort. No running out of space for activation. Fail safe Vertical force consideration can be avoided, so there will not be any first order or third order side effects. www.indiandentalacademy.com
  • Disadvantages Of Friction Mechanics  Any thing that adds the friction slows the movement of teeth along the archwire.  Unpredictable  Chances of loosing anterior torque is higher as no time given for uprighting www.indiandentalacademy.com
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  • Force applied by loops or springs Preactivation bends given www.indiandentalacademy.com
  • Loop anatomy: www.indiandentalacademy.com
  • Types of loops: 1. open loops 2. closed loops www.indiandentalacademy.com
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  • Loops and springs used for retraction: •T loop •Omega loop •Tear drop loop •PG spring www.indiandentalacademy.com www.indiandentalacademy.com
  •  Alpha moment:- this is the moment acting on the anterior teeth(often termed anterior torque). www.indiandentalacademy.com
  •  Beta moment:- this is the moment acting on the posterior teeth. Tip-back bends placed mesial to the molars produce an increased moment. www.indiandentalacademy.com
  •  Horizontal forces:- these are the mesio-distal forces acting on the teeth. www.indiandentalacademy.com
  •  Vertical forces:- These are intrusive – extrusive forces acting on the anterior or posterior teeth. These forces generally result from unequal alpha and beta moments. www.indiandentalacademy.com
  • CANINE RETRACTION BY FRICTIONLESS MECHANICS www.indiandentalacademy.com
  • FIRST LET US SEE IN THE ANTERIOR SEGMENT www.indiandentalacademy.com
  • Alpha and beta bends. www.indiandentalacademy.com
  • Alpha and beta bends. www.indiandentalacademy.com
  • Alpha and beta bends. www.indiandentalacademy.com
  • NOW LET US SEE IN THE POSTERIOR SEGMENT www.indiandentalacademy.com
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  • T loop www.indiandentalacademy.com
  •  The use of the T-loop for major cuspid retraction is recommended. It fulfills all the requirements of a retraction assembly. It is easily fabricated at the chair. It is inexpensive. It is resistant to deformation. It is easily contoured for comfort. It has a adequate M/F ratio for controlled tipping or translation.  Its M/F ration can be easily adjusted.      www.indiandentalacademy.com
  • CRITERIA FOR OPTIMAL SPRING  It should possess low load deflection     rate. It should deliver optimal force. It should deliver proper M/F ratio which determines proper C.rot. Less bulky Hygienic www.indiandentalacademy.com
  •  It is made form 0.017 x 0.025 inch TMA.  The spring is first made passive from the auxiliary tube of the first molar to the cuspid slot, it must be remembered that the canine slot is slightly occlusal to the auxiliary tube of the first molar bracket that is why distal vertical leg of T-loop is kept 1 mm short. www.indiandentalacademy.com
  • CONFIGURATION FOR THE BASIC T-LOOP SPRING 10mm 2mm 4mm 5mm 1mm ?mm 2mm ?mm Pre-activation bends www.indiandentalacademy.com
  • PRE-ACTIVATION BENDS 1st bend 2nd bend www.indiandentalacademy.com
  • 3rd bend 4th bend www.indiandentalacademy.com
  • 6th bend 5 bend th www.indiandentalacademy.com
  • Antirotation bends www.indiandentalacademy.com
  • Neutral position: www.indiandentalacademy.com
  • Trial activation: www.indiandentalacademy.com
  • Position of the loop www.indiandentalacademy.com
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  • EN MASS RETRACTION WITH FRICTIONLESS MECHANICS www.indiandentalacademy.com
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  • CONCLUSION “Well begun is half work done” so taking this guideline, meticulous attention has to be given to biomechanics. COZ IF YOU DON’T………….. www.indiandentalacademy.com
  • THINK BEFORE YOU ACT!!!! www.indiandentalacademy.com
  • BIOLOGICAL ASPECTS OF ANCHORAGE : Factors affecting anchorage:     Relation of contiguous teeth Forces of occlusion Age of the patient Individual tissue response www.indiandentalacademy.com
  • T H A N K Y OU www.indiandentalacademy.com