Tip edge mechanics

Introduction
Historical Perspectives
Creation of tip-edge
Tip –edge concepts
Bonding and setting up
Treatment stages
Stage I
Stage II
Torque in tip-edge
Stage III
Advantages
Disadvantages
Case reports
Articles
Conclusion
References

1. TIP EDGE TECHNIQUE Dr. Miliya PArveen

2. Contents: Introduction Historical Perspectives Creation of tip-edge Tip –edge concepts Bonding and setting up Treatment stages Stage I Stage II Torque in tip-edge Stage III Advantages Disadvantages Case reports Articles Conclusion References

3. Introduction: The Tip-Edge bracket was invented by Dr.Peter Kesling to introduce differential tooth movement within an edgewise based bracket system. Tip-Edge technique was first introduced at the Kesling-Rocke Orthodontic Center, Westville, Indiana , USA, in 1986. As its name suggests, Tip-Edge combines an initial degree of tooth tipping, which greatly facilitates tooth movement, prior to 'edgewise' precision finishing.

4. Historical perspectives: Dr. Edward Angle , the father of fixed appliance orthodontics created the ‘Edgewise’ Bracket in 1925. It provides the neatest way of achieving three-dimensional root control in its day. Angle himself appreciated that tooth movement was facilitated by allowing a tooth to tip . Unfortunately, he had no means of subsequent root uprighting . H is well known non-extraction treatment doctrine was best suited for his edgewise bracket.

5. Dr. Raymond Begg evolved a different bracket system that was a modification of Angle’s earlier ‘ribbon arch’ bracket. It was designed to overcome one of the prime disadvantages inherent in all edgewise systems. This is - every tooth is subject to mesio -distal bodily control from the moment of archwire engagement , thus increasing resistance to retraction. Begg introduced a new sequence of tooth movement - tipping the crowns into their corrected positions before uprighting the roots as a later procedure . Root recovery , sometimes from extreme angles, could be less than reliable M olar control and buccal segment torque were denied by the inability to use rectangular archwires .

6. T he ‘straight-wire’ bracket system, pioneered by Dr. Lawrence Andrews in the late 1970s . By incorporating in–out adjustments and finishing angulations of tip and torque into the bracket itself, individualized finishing prescriptions for each tooth became available. Such new technology set higher standards for case finishing , as defined by Andrews’ six keys to normal occlusion. Subsequent alternative prescriptions appeared, notably the Roth ‘ modified edgewise’.

7. Dr. Peter K esling , a student of Dr. Raymond B egg , evolved the design of tip edge bracket system. Because of its initial tipping followed by edgewise finishing functions, he nicknamed the slot as “tip edge”. I t is officially and more formally known as the “differential straight arch technique”. Initial crown tipping followed by controlled root uprighting with straight arch wires (differential tooth movement with straight arch wires). It converges the divergent philosophies of Begg and PEA into one bracket system with no additional use of extra-oral anchorage.

8. Creation of the Tip-Edge: Kesling modified a single straight-wire bracket to create the Tip-Edge - the Rx-1 bracket. Removed two diagonally opposite corners from the rectangular archwire slot which allowed the bracket to tip up to 25° either mesially or distally. Each bracket requires a n auxiliary in the final stage in order to deliver root correction and coming of the latest Ni-Ti wires – TE Plus brackets These had a horizontal ‘deep tunnel’ in the bracket base allows torquing and tipping powered by a light Ni-Ti auxiliary archwire

9. Bracket face - Conventional tie-wings for elastomeric ligature. Bracket identification - small circular markers on disto -gingival tie wing for maxillary anteriors & triangular for mandibular. The ‘cut out surfaces’ of the archwire slot form the ‘ tip limiting surfaces ’ - restrict the degree of tipping permitted during tooth translation. The intact surfaces - the ‘ finishing surfaces ’, containing the individualized finishing prescription for each tooth. The point at which the tip-limiting and finishing surfaces meet constitutes the central ridge ; the opposing central ridges provide vertical control until final finishing . The laterally extended surface lingual to the main archwire preserves rotational control throughout the range of tip permitted by the bracket .

10. Bracket SLOT - Slot size : 0.022”X0.028 ” is called the propeller slot. It is a ‘dynamic ’ slot because: Unique feature that the slot increases its vertical archwire space from 0.022 to 0.028 inches as the tooth tips When the vertical slot is closed down by the auxiliary against a rectangular archwire , it produces a three-dimensional precision finish. I t reduces friction during the first stage of treatment. Vertical slot is 0.020 inches square, lingual to main. Has a rounded ‘funnel shaped’ entry to facilitate insertion of auxillaries .

11. The first molar tubes - Tip-Edge employs double buccal tubes – a normally sited preadjusted straight-wire rectangular tube of . 022 × . 028” a gingivally placed round tube of . 036” diameter. The first comes with a convertible rectangular buccal tube and tie-wings so that the tube can become a bracket when the buccal welded insert is peeled away - facilitates alignment of second molars. Non-convertible molar tube has been introduced - carries no tie-wings, helps patient comfort and reduces the chance of occlusal interferences . All rectangular tubes are of Easy-Out® design , with the posterior inner lumen slightly flared towards the occlusal - facilitate archwire removal when a cinch back has been used

12. 4. Auxiliaries - The Side-Winder U sed to be the everyday ‘workhorse’ among auxiliaries. Primarily in Plus , it generates mesio -distal root movement. For the Rx-1 bracket - produces torque correction as well, when used with rectangular archwires . Made in . 014 inch high tensile stainless steel wire. So called because it carries its coils along the archwire , over the bracket face . Side-Winders - only be used with SS arches, others are insufficiently stiff to resist the vertical deflections arising from the active arms of the springs .

13. Invisible side-winder springs Wire of spring lies on archwire & brackets. Advantages Aesthetic Retained in position by the elastomeric module, in addition to its own spring pressure - reduces the risk of detachment Enables modules to be changed if necessary during the root uprighting process without removing springs. Because the bulbous hook has been reduced, the spring arm has a wider range of activation S teel ligature ties avoided – insufficiently elastic to allow the bracket to rotate relative to the archwire , as is necessary for the correction of tip (and torque ) - therefore restricts the action of the spring.

14. Side-Winder springs should always be inserted from the occlusal and never gingivally . The action of the spring will be the same either way but the forces of mastication coming from the occlusal will be deflected harmlessly off and if gingivally inserted, it will be distorted. The direction of action of each spring can easily be ‘ read’ in the mouth by the clinician, according to the direction of the spring arm. Since each spring is inserted occlusally , the spring arm points in the direction towards which the occlusal tip will rotate. O ut of the mouth, hold the spring in a plier , hook facing the operator - starting from its free end, if the hook curves away in a clockwise direction, it is a clockwise spring, and vice-versa

15. C. Power Pin This is a traction hook that can be fitted in the vertical slot Made of soft stainless steel, inserted from the gingival, and is retained in the slot by bending the occlusally projecting tail 90 degrees. Strictly , this bend should be made in the opposite direction to the elastic pull, since this avoids the possibility of a slackly turned pin doing a ‘U-turn’ and being pulled out of the slot by the elastic . M ost commonly used as hooks for seating elastics in the final treatment visits. Also useful when an individual tooth requires retraction . Using an elastomeric to a Power Pin, instead of directly to the bracket, reduces the risk of distal rotation, since the bracket is secured by its own elastomeric module (instead of by the end link of elastomeric chain, which will inevitably be stretched open by the traction)

16. D. Rotating Spring Seldom required for correcting initial rotations – because rotations of anterior teeth are dealt with by full bracket engagement with light Ni-Ti wires. V ery useful for recapturing a rotation that has recurred in treatment, particularly if the patient is in a heavy archwire . E.g if a ligature or a bracket has detached from a previously rotated tooth - convenient to be able to realign the rotation with the flexibility of an auxiliary spring, than stepping down to a lighter archwire . C omes in clockwise and counter-clockwise versions Made in .014 inch high tensile stainless steel.

17. By using elastic ligatures in the normal way , there is a risk that ligature failure or stretch may allow the spring arm to displace the crown lingually . The difference between wire or elastic ligatures is that a wire tie will limit the action to a perfect alignment, while an elastic ligature will allow some degree of over-rotation . T he ligature should be placed first , before inserting the spring . A wire tie should only secure the archwire on the side of the bracket which is contacting the archwire and the ligature should run around the backplate , rather than across it. To avoid occlusal interference, Rotating Springs should always be inserted gingivally

18. E . Tip edge rings Elastomeric rings designed to function with tip-edge brackets. Provide both arch wire attachment and mesial or distal tip control in Stage III by filling the chamfered wedge area. It parallels the archwire with the gingival and occlusal edges of the tie wing tips. This is called “ hammock effect ”. These rings are normally used only in the final stage of treatment to maintain the crown uprighting achieved with springs.

19. F. Straight Shooter A ligature gun, invented by Dr. Peter Kesling , is ideally suited to Tip-Edge. Made from autoclavable plastic. Secure in position and press the trigger - the ring is released. Advantages, Less time consuming Places less pressure on the tooth ,more comfortable for the patient Needs less concentration from the operator Safer

20. G. E-links Space closure is carried out using elastomeric E-Links. P referred to elastomeric chain, the force of which can only be crudely adjusted according to the number of links chosen . E-Links come in graded lengths with a working life of up to 3 months in the mouth. R uns from the buccal hook on the first molar to the cuspid circle. A long strand of elastomeric running parallel to the archwire can be routed beneath the retaining module on the premolar .

21. H . Outrigger appliance – A utomatically reminds non-compliant patients to replace the elastics by flicking out sideways whenever the elastics are not attached . C onsists of a pair of hooks, coiled on the end of an interconnecting span made in .016 inch. Seated in the occlusal tie-wings of the upper central and laterals using ‘ bilevel pins’.

22. TIP EDGE CONCEPTS:

23. Differential tooth movement - The very design of the edgewise derived brackets exerts mesiodistal second order root forces from the time of first engagement with an archwire . Yet it is recognized that positioning a root apex toward the direction of pull will generate resistance to tooth movement in response to that force. Dr. Charles Tweed developed the concept of ‘anchorage preparation’, moving his apices mesially in the mandibular buccal segments so as to increase anchorage resistance to Class II elastic traction. (Tent- peg analogy)

24. A bracket designed for differential tooth movement will not impart root-angulating forces when an archwire is engaged. Instead , the crown will be able to tip in the direction of desired tooth movement, essentially leaving the root apex to trail behind. Such simple free tipping requires far less force and anchorage than moving the same tooth bodily, although this would in itself amount to incomplete treatment - makes initial decrowding and reduction of big overjets dramatically easy and rapid. This lends stability to the subsequent root uprighting process - by establishing a strong interdigitation and bringing the labial segments within the safety of normal lip control.

25. VARIABLE ANCHORAGE - With differential tooth movement, root control of the bracketed teeth can be prescribed by the operator, rather than occurring automatically from first archwire engagement. This can be simply done by the addition of an auxiliary (Side-Winder) spring or springs, as was the case with the Rx-1 bracket. The orthodontist now has the choice of which roots to control and when, perpetuates the concept of variable anchorage control. This was not possible with conventional brackets, without resorting to more complicated add-ons such as lingual arches, headgears or other anchorage reinforcement.

26. Light forces - It is fundamental to differential tooth movement that all forces should be light. A mere 50gms of intermaxillary elastic force bilaterally is quite sufficient for the reduction of even large overjets . Heavier forces - unnecessary and harmful - posterior anchorage will be strained and periodontal ligament put at risk. Differential tooth movement naturally implies a differential periodontal response - tipping a tooth will induce most root movement at the gingival, diminishing towards the apex - forces are therefore less evenly dissipated along the root. With light forces, this will not present any hazard .

27. Root uprighting - Edgewise & straight wire brackets offer very poor recovery from tipped angulations. Correction of mesio -distal crown tip by engaging the brackets with an active archwire provokes major vertical consequences with extrusion of adjacent teeth. Use of power arms may facilitate the uprighting process but the vertical archwire deflections remain . In tip edge recovery is by the light and progressive action of auxiliary springs . The vertical arch stability is maintained by relatively heavy but passive archwire

28. Bonding and setting up : T he Tip-Edge appliance should be set up just like any other straight-wire appliance . Some noted features will be explained under – Bracket placement Premolar brackets Molar banding

29. 1. Bracket placement - Each bracket should be aligned with its vertical axis parallel with the long axis of the tooth, and at the mid-point of the crown mesio -distally. The height of the bracket should be at the vertical mid-point of the fully erupted clinical crown. Being a smaller bracket has aesthetic advantages, but also makes the accurate placement more difficult - supplied with the option of plastic jigs. These provide ready ‘sight lines’ for the correct angulation and make the brackets much easier to handle with conventional bonding tweezers.

30. The jigs were produced only in ‘L-shaped’ form, which prescribes a fixed bonding height for each bracket from the incisal edge or tip, as denoted by the colour coding. Jigs can be modified by cutting off the horizontal section leaving only straight vertical markers Universal jigs are more recent and can easily be aligned up the long axis of the tooth, while the mid-crown height can be gauged by eye.

31. 2. Premolar brackets - A nterior t ip-Edge brackets are designed to allow distal crown tipping but premolars may require to tip either mesially or distally, according to the extraction pattern . E.g : In a first molar extraction case, a second premolar will require to tip distally. I f first premolars have been extracted, the same second premolar will need to tip mesially into the extraction space. Simplified bracket selection by using identical torque and tip values in upper 1 st and 2 nd premolars – only need to check whether the bracket is an upper or lower, and if it is required to tip clockwise or counter-clockwise .

32. Upper premolar brackets are identified by circular markings on the tie wings, lowers by triangular markings. These are offset towards the direction of tip. On the occlusal tie wings, an arrow is an additional indicator of the direction of rotation. In various possible extraction patterns, the arrows usually point towards the extraction site and in a non-extraction case, towards the distal. A s a rule of thumb, all the arrows point distally , except second premolars in first premolar extraction cases

33. 3. Molar bands - U se of bonded first molar tubes is contraindicated - the withdrawal of the rectangular archwires at the end of Stage III is likely to cause bond failure . The rectangular buccal tubes should be aligned to the brackets , at mid-crown height, just as with a straight-wire appliance. The round tube will sit towards the gingival margin . In the mandibular arch, the tubes should be parallel to the occlusal cusps; in the maxillary arch, seating the band fractionally higher toward the distal may be helpful in obtaining final seating of the disto-buccal cusp.

34. Treatment stages :

35. Stage I : Objectives: 1. Initial alignment of upper/lower anterior segments 2 . Closure of anterior spaces 3. Correction of increased overjet or reverse o verjet 4. Correction of increased overbite or AOB 5. Work towards arch coordination

36. Mechanics: 1 . Place upper and lower 0.016 SS base archwires with cuspid circles just mesial to the canine brackets and gently engage all possible teeth into round molar tube. 2. Severely displaced teeth can be engaged with elastic thread passed through the vertical slot . - Round nickel–titanium underarch , usually of .014 inch diameter can be used to align instanding anterior teeth, 3. Leave out the premolars .

37. 4. Place gentle anchor bends in front of the molars, placing the base archwire in the gingival slot. These bends reciprocally intrude incisors by the idea of ‘’dig in heels’ of lower molars to resist the light mesial pull of the elastics.

38. 5. Once anterior alignment has been achieved, each canine bracket should be ligatured to its respective cuspid circle with an elastomeric. Purposes : the canines are prevented from unwanted further distal migration, so that the anterior segment will not become spaced the archwire is stabilized laterally, and cannot swing from side to side . 6. Use Class II elastics (60g only) from circles on the upper archwire to the lower 6’s.

39. 7. Power tipping: If unwanted proclination of lower incisors during overbite reduction, utilize ‘reverse Side-Winder springs ’ – induce distal crown torque to the lower canines, and hence distal retraction , which in turn uprights the lower anterior segment lingually

40. 8. The Protraction Arch: In non-extraction cases with mildly crowded lower incisors, a small amount of proclination of the incisors is deemed permissible. Fabricated from the same wire, .016 inch high tensile stainless , cuspid circles are placed at least 3 mm distal to the canine bracket Protraction is activated by means of an elastomeric module stretched between each canine bracket and the circle behind it As the elastomeric contracts, the archwire will be drawn forwards through the molar tubes, making more wire available at the front, allowing the incisors to align onto a bigger curvature.

41. STAGE II: Objectives: 1. Closure of residual spacing - by retraction of labial segments or by protraction of buccal segments. 2. Correction of centrelines. 3. Derotation of first molars. 4. Levelling of first molars. 5. Continuing crossbite correction. 6. Maintenance of Stage I corrections.

42. Mechanics: Premolars should be included prior to the start of Stage II and use the same archwires after removing the anchorage bends and replacing them with vertical bite sweeps ,(reverse curve of spee ) to retain the overbite reduction. The wire is inserted into the rectangular molar tubes. Correction of premolar displacements and rotations can be corrected with elastomeric E-Links, elastic threads or an .014 inch nickel–titanium underarch.

43. 3. T he archwire size is then increased to 0.020” round SS. 4. W hen closing buccal segment spacing , by class one elastic by using E-links between the circles on the archwire to the hooks on the 6’s, it is possible to choose between retraction of the labial segment or protraction of the posterior segment by adding adding Side-Winder ‘brakes ’.

44. 5. In view of a centreline discrepancy , consider using unilateral sidewinders. - The centreline is to the patient’s right, where the extraction space closed . Closure of remaining space will automatically correct the centreline without the need for a brake. - With a correct centreline , a defensive brake is now required to the left canine, so that space is closed by protraction.

45. - The centreline needs correcting into the patient’s left quadrant space, by retraction, whereas the space remaining in the right quadrant must be closed by protraction. The lower right canine is therefore braked and an additional side-winder is placed on the right central incisor, for distal root movement.

46. 6. A limited amount of first molar rotation can be expected as a result of space closure with free-sliding mechanics . Requires a simple adjustment to the archwire , placing a 1 mm buccal offset and 10 degrees of lingual toe-in opposite the interspace between the fi rst molar and premolar To prevent space recurring, the distal archwire ends should be annealed and turned gingivally .

47. 7. Leveling of molar should done to allow the placement of rectangular archwires Anti-tip bend of 10 ° opposite to premolar-molar contact point. Ensures seating of the distal cusp of tipped molars 8. Maintain Class II elastics as required to keep the upper and lower incisors in gentle contact.

48. Torque in tip-edge : A conventional edgewise or straight-wire bracket has flaws, Rectangular wire required to provide active torquing and offering three-dimensional stability to the remainder – physical impossibility active torque imparted to a single unit, or quadrant - unwanted secondary torque reactions in adjacent units flexibility of a nickel–titanium archwire preferable for torquing with light forces but stainless steel preferable for maintaining stability. nearly 10 degrees of ‘torque slop’ between .019 × .025 inch archwire and .022 × .028 inch bracket slot

49. A Tip-Edge bracket cannot be torqued by an active archwire in the conventional manner as intact upper and lower finishing surfaces in each bracket are offset from one another, and are therefore never directly opposed. Insertion of an actively torqued rectangular archwire will elevate one finishing surface and depress the other - torquing effort in the archwire dispersed by increasing the vertical dimension within the Tip-Edge slot. The net result - relapse of root uprighting in the mesiodistal direction - ‘ torque escape’.

50. Originally torqueing required a Side-Winder for each individual bracket but in the Plus bracket all torquing and tipping can be carried out with a Ni-Ti auxiliary archwire , threaded through the deep tunnels. In Stage III, a stainless .0215 × . 028 inch archwire can be fitted without difficulty due to the excess vertical dimension of slot. No torque will therefore be imparted at this point except in first molars.

51. The vertical deflections of the auxiliary archwire (.014”) in the deep tunnels will generate tip correction . After some initial correction of tip, a point is soon reached when further closing down of the bracket becomes obstructed by the opposite corners of the rectangular archwire . A two-point contact is thus established within the bracket.

52. W hen the bracket becomes fully closed down to the vertical dimension of the archwire , the upper and lower flat surfaces of the bracket slot will be in contact with the flat upper and lower surfaces of the archwire . The rectangular archwire cross section remains undeflected throughout the entire torquing process, thereby the wire can torque teeth individually, without unwanted torque reactions to neighbouring teeth . In short, i nstead of increasing archwire thickness to fill the bracket , a Tip-Edge bracket shrinks its vertical dimension ( under pressure from an auxiliary) to fit a full sized archwire , conforming to it precisely in all three dimensions.

53. Stage III: Objectives : 1. Maintain Stage I/II changes 2. Correct torque and Tip 3. Detailing & finishing

54. Mechanics: 1. Archwire : 0.0215 ” x 0.028” stainless steel base wire- flat or pre-torqued and place crimpable hooks between canine and lateral incisor. 2. Using Side Winder springs or piggy back 014 or 016 NiTi in TE plus - Thread the auxiliary wire first using midline or distal aproach .

55. 3. Maintain the space closure using ligatures from crimpable hooks to the hook on the molars . 4. Use Class II elastics to maintain light contact between the upper and lower incisors . 5. Final finishing to be done along with second molar alignment and occlusal seating. This should be followed by a long-term retention protocol.

56. Advantages: 1 . Increased inter-bracket span because of the reduced bracket size MD 2. Little need for HG 3. Less anchorage demand because, Differential force theory and light force Less expression of the tip during the first stage of treatment Round wire with reduced friction during the first stage of treatment 4. Precision in finishing 5. TE bracket can be used with SW in case of p roclined or retroclined canines

57. Disadvantages: 1. Expensive 2. Extraction philosophy and possible profile dishing 3. Reliant on elastic wear 4. Poor rotational control 5. High risk of root resorption and risk of PD damages 7. Complex in stage III specially the old TE system because each bracket requires an auxiliary spring to deliver its final prescription. 8 . Increased friction in later stages

58. Case reports : Case report 1 : A severe Class II division 1 malocclusion with increased overbite on a very low mandibular angle Class II base treated with the Plus bracket

59. Case Report 2 : A severe Class II division 1 malocclusion with a marked unilateral overjet treated with the Plus bracket

60. ARTICLES :

61. Conclusion: The tip edge bracket provides varying degrees of tooth control not previously available in an edgewise type bracket. It also offers advantages over ribbon-arch ( Begg ) brackets through ease of manipulation provided by the horizontally facing slot plus predetermined limitation of initial crown tipping and control of final root uprighting . But further studies need to be conducted to determine the true efficiency of this bracket system over the currently accepted treatment protocols.

62. Refernces : Tip-Edge Orthodontics and the Plus Bracket - 2nd Edition,   Richard Parkhouse Parkhouse , R. C. (2007).  Current products and practice: Tip-Edge Plus. Journal of Orthodontics, 34(1), 59–68.   doi:10.1179/146531207225021933 Kesling PC. Dynamics of the Tip-Edge bracket. American Journal of Orthodontics and Dentofacial Orthopedics. 1989 Jul 1;96(1): 16-25 Kesling PC, Rocke RT, Kesling CK. Treatment with Tip-Edge brackets and differential tooth movement. American Journal of Orthodontics and Dentofacial Orthopedics. 1991 May 1;99(5): 387-401.