LOOPS in orthodontics t loop bull loop vertical loop mushroom loop stop loop

vertical loop
horizontal loop

1. LOOPS

2. CONTENTS Introduction History Orthodontic Forces Force Control Wire-Clinical Consideration Loop activation for force control Loop Design Bauschinger Effect Classification Of Loops Vertical Loops Horizontal Loops Transverse Loops Anchorage consideration conclusion

3. INTRODUCTION Optimum control of tooth movement requires the application of a specific orthodontic force system. So we need to have a clear idea about the mechanics of the orthodontic appliances to achieve a predictable and desirable result.

4. How to achieve treatment efficiency? .1.Continuous forces 2.Acting on a wide area 3.Working in the correct direction(direction in which tooth is to be moved) 4.Maximum comfort to the patient All this can be accomplished successfully only by the precise application of different size, shape and type of loops, having a control on the distribution, direction, degree and duration of force applied.

5. HISTORY The principles and uses of vertical loops was first described by RAY ROBINSON in 1915 who was an early advocate of light wires and light continuous forces by means of loops. He summarized that except the force of gravity, there is probably no force so constant in its operation as that of a coil spring as even as the pressure of the atmosphere varies with temperature change. STRANG was the first to introduce loops into this edgewise technique. BEGG IN 1956 explained the advantages of different loop configuration in arch wire design and activation.

6. ORTHODONTIC FORCES Orthodontic forces are of two types Primary -Developed in the arch wire and depend on the resiliency or movement of the arch wire. This type of force can be manipulated by increasing the resiliency of a wire by the incorporation of loops. Secondary -Forces that are designed from auxillary attachments such as finger springs, rubber bands, headgears etc

7. BASIC PRINCIPLES OF FORCE CONTROL The best way to understand the activity of any loop is to understand what rules apply to any deflection in a wire. There are 4 D’s in force control Degree of force -Amount or intensity of force. Distribution of force -The manner in which the force is transmitted to the root surface or alveolar process.

8. Direction of force - Direction of the force should be in the plane in which the tooth is to be moved. Duration of force - Range of activity of applied force

9. CLINICAL CONSIDERATION Range Of Deflection - The distance that a wire can be deflected before it undergoes permanent deformation. Force - An influence tending to change the motion of a body or produce motion/stress in stationary object. Calculated by multiplying the mass of the body with its acceleration. Elastic Limit - The maximum extent to which a solid may be stretched without permanent alteration of size or shape.

10. Variation In Diameter a. The magnitude of force that can be developed through deflection of a wire is proportional to the fourth power of number of times by which the diameter of the wire is changed. F * D4 So if the diameter is doubled, the force exerted by it will become 16 times more. b. The relationship of the diameter to the maximum load before permanent deformation takes place varies directly to the 3 rd power of the increase in the diameter. Total load Capacity * D3 c.The elastic limit will vary inversely with the increase in diameter. Elastic limit * 1/D

11. Variation In Length Magnitude of force value per unit of deflection will decrease in proportion to the cube of the difference in length. F * 1/L3 The force that can be developed, decreases 1/8 th when the length of the wire is doubled. Increase in length will proportionally decrease the maximum load. Twice the length allows half the maximum load. Elastic limit increases proportionally according to the square of difference in length. Elastic limit * L2

12. LOOP ACTIVITY FOR FORCE CONTROL General rules to be followed 1. Any loop will reduce the force and increase the range by adding wire in the inter-bracket span. 2. Any loop may be contoured ‘open’ or ‘closed’. 3. The force of any loop may be reduced by coiling the wire at the apex one or more times.

13. 4. Loops are most efficiently activated through compression of the legs. 5. The forces developed in the loop or the archwire will be transmitted to the tooth through the bracket attachment as a tipping or a bodily force depending upon the contour and method of activation. 6.The force reduction affected by contouring most loops will be in direct proportion to the increase in the amount of wire between the brackets.

14. LOOP DESIGN One important consideration in loop design is that the legs of a loop should always be contoured at right angles to the desired direction of activity The loop should be “ fail safe ”. This means that, although a reasonable range of action is desired from each activation, tooth movement should stop after a prescribed range of movement even if the patient does not return for a scheduled adjustment .

15. Design should be as simple as possible. A loop is more effective when it is closed rather than opened during activation.

16. THE BAUSCHINGER EFFECT If a straight piece of wire is bent so that permanent deformation occurs and an attempt is made to increase the magnitude of the bend, bending in the same direction as had originally been done, the wire is more resistant to permanent deformation than if an attempt is made to bend in the opposite direction. The wire is more resistant to permanent deformation because of certain residual stress remains in it after placement of the first bend.

17. If a bend is made in an orthodontic appliance, the maximal elastic load is not the same in all directions, it is greatest in the direction identical to the original direction of bending or twisting. The phenomenon responsible for this difference is known as bauschinger effect.

18. CLASSIFICATION OF LOOPS According to function( jarabak 1963) 1. Vertical : Vertical loop is most efficient in moving the teeth in antero -posterior direction . 2. Horizontal : moves teeth in vt direction 3. Transverse : moves teeth most efficiently in mediolateral direction.

19. 2. Based on purpose of the loop (a) Leveling and Aligning ( b) Retraction ( c) Multipurpose 3 . Based on presence of helix ( a) Loops without helix(e.g. vertical loop) ( b) Loops with helix(e.g. Helical bulbous loop) 4 . Based on function ( a) Opening loops ( b) Closing loops

20. VERTICAL LOOPS Used for first order discrepancies( Labio -Lingual or mesiodistal ) The vertical loop has two vertical components and may be activated in any plane perpendicular to these components. Two types- 1. Open- A . Efficient in opening space B . Used to rotate a tooth C. Average rate of decrease of force is 60.5gm/mm

21. 2. Closed- A . Primarily used to close space Average rate of decrease of force is 41.4gm/mm

22. HELICAL LOOP It is 3 separate springs made up into a single unit. Helix could have 1½ turns or 2½ turns , that would include several millimeters of wire without making the loop any longer. The initial force that is developed is less than that obtained with a simple loop. But, the decrease in force per mm of distance returned is always less, hence more resilient active element leading to greater working range.

23. FUNCTIONS OF VERTICAL HELICAL SPRINGS To increase arch length in one part of the arch for the repositioning of the malaligned teeth. Used as an expansion device to create space for the alignment of teeth. Used as highly elastic rotation device. Used to distally drive canines in the treatment of malocclusion when the 4 1 st premolars have been extracted. Minor levelling adjustment can be made to reduce excessive curve of spee by placing loops between each of the posterior teeth.

24. VERTICAL LOOP- Both open and closed vertical loop was given by Robert Strang in 1933 Length-6-8mm Width-1.5mm 1.Used mainly for retraction of anterior teeth. 2.To open spaces 3.To rotate teeth

25. In Beggs mechanotherapy , anterior tooth alignment is accomplished with archwires incorporated with vertical loops. The loops increase the wire span between the teeth and produce a gentler pressure during movement The loops are then activated to produce overcorrection of rotations, labio -lingual or mesio -distal movement

26. BULL LOOP- Was given by Harry Bull in 1951 Also known as Squashed Vertical Loop

27. USED FOR: Retract the anteriors Closing of spaces It is activated by opening the loop An advantage of the use of this loop when used for class II correction in conjunction with class II elastics is that they do not procline the mandibular anteriors since the closing loops restrain this effect

28. VERTICAL LOOP WITH HELIX- Given by Dr Moris Stoner in 1960 Loop incorporated to increase the working range

29. The force from the cantilever arms give direction to this whole force system while the cross section geometry of the wire, its modulus of elasticity, diameter, number of turns in helix and the length of the arms control the force magnitude of this highly elastic system lateral extension coils not only increase flexibility but also reduce the tendency to tip adjacent teeth as they are being moved

30. Stop loop

31. OMEGA LOOP- Given by Dr Moris Stoner in 1960 Advantage of this loop is that it tends to distribute stresses more evenly through the curvature of loop instead of concentrating than at apex .

32. Selected to apply moment to last tooth in arch It causes bodily movement of root This loop can also be used as a stop loop

33. TEAR LOOP The ideal force applied to achieve movement of the mandibular incisors

34. HORIZONTAL LOOP/BOOT LOOP introduced by stoner in 1960 They are designed such that the active legs are parallel to the archwire Principle value is its reduction of force in the vertical plane or occlusogingival direction. It is effective in aligning the brackets when it is necessary to open the bite or to depress or elevate the anterior or posterior segment. It is possible to contour the horizontal loop to press against the gingival area to develop a torquing activity on the root

35. The supraversion and linguoversion of the maxillary central incisor and infraversion and labioversion of lateral incisor in class 2 div 2. To create effective force to extrude maxillary canine that has delayed in eruption.

36. Efficiency of the double Horizontal Loop is best when kept on an individual tooth either above or below the line of occlusion. It can be activated in an occluso -gingival and labio -lingual plane but not in the mesiodistal plane. One loop can be contoured to elevate and the other loop can be contoured to depress, tending to tip the tooth or move the roots

37. T LOOP- Given by Dr Charles J Burstone in 1972 Can be segmented or unsegmented . Helps in closing of spaces. Helps in opening of bite. When this loop is used with a rectangular wire the range of torque action is increased,because of the greater amount of wire in the horizontal plane.So,this loop eliminates the undesirable occlusal or gingival deflection of the arch-wire when activated, which may produce a tipping movement. So this loop causes elevation or depression in the true vertical plane.

38. Segmented t loop T loop in continuous arch

39. Asymmetrical T loop Asymmetric T loop was described by James Hilger in 1992 . Activation of asymmetric T loop is done by compressing short mesial loop and opening long distal loop.

40. BOX LOOP- Given by Dr A Sivakumar in 2006. Used for alligning of asymmtric crowding in early permanent dentition. Root paralleling. Uprighting of tipped molars.

41. Mushroom loop Mushroom loop was given by dr flabio uribe and dr ravindra nanda in 2003 . The mushroom loop neither interferes with the gingival tissue nor does it distort easily thereby improves the delivery of orthodontic load. Used for closing of spaces .

42. Double delta loop The double delta loop serves to close spaces. It is also frequently used for the leveling and integration of the arches.

43. K-SIR arch K-SIR arch which stands for Kalra – Simultaneous Intrusion and Retraction was developed by Dr. Varun Kalra It is a modification of the segmental arch technique of burstone as applied to continuous arches

44. Its advantages include simplicity in design and fabrication, comfort to the patient and less chances of tissue impingement. As it carries out en-masse retraction it abbreviates orthodontic treatment time compared to conventional edgewise mechanics. Also, this prevents the appearance of an unsightly space distal to the laterals which is seen in individual canine retraction.

45. TRANSVERSE LOOPS Moves the teeth most efficiently in the medio -lateral direction, i.e. tipping of molars, pre-molars bucally or palatally hence affecting inter-canine, inter-premolar or inter-molar width. The high elasticity at a low force magnitude,which can be built into a transverse helical loop appliance, makes this appliance ideally suited for retrieving palatally erupted canine and lingually erupted pre-molars. It is also used for elevation of submerged pre-molar in cases where oral vestibule is shallow.

46. Anchorage considerations in the employment of loops If a desired tooth movement is readily responsive and the reactionary forces of loop to be used are directed against teeth in a direction that is highly resistant, the operator can expect the loop to accomplish its objective without complications . But the operator must be concerned with the reciprocal forces produced by a loop employed for a highly resistant movement such as root tipping. These forces can cause readily responsive tooth movements to occur in an undesired direction.

47. Anchorage in the area adjacent to a loop is developed through the rigidity of the comparatively short sections of wire in the interbracket span When two loops are employed on either side of a tooth and activated in the same plane, the activity of the combination of loops is confined essentially to the tooth between the loops and anchorage is developed in the adjacent teeth through the rigid section of wire . Heavier gauge archwires are better able to resist displacement when highly resistant tooth movements are required

48. CONCLUSION The modification of arch wire shape with the inclusion of loops has been advocated for a number of reasons. These included the improved resiliency of an appliance between adjacent teeth significant reduction in the customary number of clinical adjustments. diminished force values could be applied to provide improved control over individual tooth movements

49. several different types of loops selected for specific movement of a single tooth

50. Loops are usually included in the initial alignment archwire to attain bracket alignment, however loops also may be used in other stages of treatment, such as Mesial or distal movement– Double vertical loop or a combination of open and closed vertical loops . Space closure – closed vertical loop, tied back . Space opening – open vertical loop, with stops . Bite opening – T loops mesial to canine can be used

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