Self ligating brackets lecture

rms

1. Self-Ligating Brackets By: Dr. Hadeel Almasri

2. Lecture’s Outline Definition Overview of evolution of self-ligating brackets Classification Properties of an Ideal Ligation System Disadvantages of the conventional ligation system Advantages of self-ligating brackets Clinical significance of low friction T reatments not influenced by a low-friction method of ligation Factors which have hindered the adoption of self-ligation Commonly used SL system Active clip or passive slide ? Clinical tips when using self-ligating brackets Archwires Debonding Retention

3. Definition Self-ligating brackets have an in-built metal face, which can be opened and closed . The Russell Lock edgewise attachment first described by Stolzenberg (Russell Lock edgewise attachment) in 1935 was the early examples of self-ligating brackets.

4. Overview of evolution of self-ligating brackets

5. Classification Active : Have a sliding spring clip, which encroaches on the slot from the labial aspect, potentially placing an active force on the archwire . e.g : Speed, In-Ovation, Nexus, Quick, Time Passive : Have a slide that opens and closes vertically and creates a passive labial surface to the slot with no intention to invade the slot. e .g : Damon, Smartclip , Praxis Glide, Carriere LX, vision LP, Lotus.

6. Properties of an Ideal Ligation System Inexpensive Biocompatible material Assist good oral hygiene and patient comfortibility . Be quick and easy to use. Be secure and robust. Ensure full bracket engagement of the archwire . Exhibit low friction between the bracket and the archwire .

7. Disadvantages of the conventional ligation system Fails to provide and maintain full arch wire engagement. High friction. Elastomerics exhibit force decay and loose tooth control. Impede oral hygiene. Wire ligation is a very slow process.( Wire ties have lower friction and engage the archwire fully in the bracket, however they time consuming.)

8. Advantages of self-ligating brackets S ummarized in a systematic article by Fleming et al in 2010 and Chen et al 2010

9. Improved movement control by Secure and robust ligation With: -This can maximises the potential long range of action of modern low modulus wires and minimises the need to regain control of teeth where full engagement is lost during treatment due to degradation as in elastomeric modules . - Wire ligatures are good in this respect, whilst elastomeric ligatures are much less good, The force decay of elastomerics has been well documented ( Taloumis et al 1997).

10. Less chairside assistance and faster archwire removal and ligation With ： - Harradine 2001, SL brackets reduce placement time of an archwire by 24 sec per wire . - Bernie 2005 have shown that wire ligation is very slow compared to elastomerics , the use of wire ligatures added almost 12 minutes to the time needed to remove and replace two archwires . Against: - In a meta-analysis by Chen 2010 reported mean time savings of 20 seconds per arch. This considered insignificant and would not make many operators change their practice.

11. Assist good oral hygiene With: - Elastomerics accumulate plaque more than do tie-wires. - The ends of wire ligatures are however an additional obstacle to oral hygiene. - The bacteriology results slightly favoured wire ligation, the important sign of bleeding on probing was substantially higher with elastomeric ligation. Turkkahraman et al (2005)

12. Patient comfortibility With: - Mills (2006) in a split mouth study found lower pain levels with Damon 2 brackets during the alignment phase, although opening the brackets was more uncomfortable than removing elastomerics . Against: - Pain during alignment stage is similar between victory, Damon and smart clip (Fleming 2008, Scott 2009) even SL has worse pain level in replacing 19*25 NITI with ss.

13. Low friction between bracket and wire with associated rapid treatment, b etter treatment quality and outcomes and less root resorption With ： The low friction and low force philosophy claimed to be the cause of: Rapid movement Little proclination Less anchorage demand Better arch development Wider arches which may be more aesthetic Wider arches which have better periodontal health than those resulting from more rapid and forceful expansion

14. Low friction between bracket and wire with associated rapid treatment, b etter treatment quality and outcomes and less root resorption Less need for extractions Easier class 2 correction through a ‘lip-bumper’ effect Better stability. Less root resorption.  Study to support this done by Harradine 2001 , Treatment time with SL brackets was on average 4 months shorter than conventional brackets. The mean number of visits was reduced from 16 to 12 per patient.

15. Low friction between bracket and wire with associated rapid treatment, b etter treatment quality and outcomes and less root resorption Against: - NO difference in time or efficiency during initial alignment according to Mills 2005 , Scott 2008, Fleming 2009, Pandis 2011, Eliades 2008. This result in upper and lower arch similar. - During Enmass space closure (no difference in time or efficiency)) according to Mills 2007 - During canine retraction (no difference in time or efficiency) according to Mezomo 2011 - Overall treatment duration, Fleming 2010, DiBiase 2011, Johannson 2012 no difference - Songra 2014 SL is worse than conventional

16. Low friction between bracket and wire with associated rapid treatment, b etter treatment quality and outcomes and less root resorption - PAR index improvement (no difference ) DiBiase et al 2011, Johannson 2012 . - Harradine 2001, SL and conventional systems produced the same PAR reduction . - Regarding the maxillary arch width, Fleming in 2013 did a study where he randomized a sample of 96 patients aged 16 and above to treatment with a passive self-ligating bracket, an active self-ligating bracket and a conventional system. Importantly, they removed the effect of archwires by using the Damon archwire sequence for all patients. They found no difference and the expansion is related to the wire not the appliance.

17. Clinical significance of low friction Rapid movement : With elastomeric ligation, higher forces must therefore be applied to overcome the resistance produced by friction and this is more likely to be undesirably higher than levels best suited to create the optimal histological response resulting in slow movement.

18. Clinical significance of low friction Less anchorage demand : With low friction, the net tooth-moving forces can be more predictably low so there will be less anchorage loss. A recent study by Yee et al (2009) measured canine retraction and anchorage loss with a light (50 gm) and heavy (300 gm) forces. The percentage of anchorage loss was significantly higher (62%) with the heavy force than with the light force (55%).

19. Clinical significance of low friction Little proclination and better arch development : Light forces aid in that the forces from the soft tissues can compete with the force from the wire. For example it has been proposed that the lips can restrain labial movement of the incisors and that the alignment of crowded teeth on a non-extraction basis will result in more lateral arch expansion and less labial incisor movement than would be the case with heavier forces and higher resistance to sliding.

20. Clinical significance of low friction Better stability : Further, it’s been claimed that expansion brought about by such light forces is more likely to achieve an archform which is in balance with the tongue and cheeks and can establish a wider arch which will be relatively stable because of altered tongue position.

21. Treatments not influenced by a low-friction method of ligation Space closure with closing loops placed in the space Expansion of a well-aligned arch Torque (inclination) changes

22. Factors which have hindered the adoption of self-ligation Design and manufacture imperfection. An inherent conservatism amongst orthodontists Lack of widespread appreciation of what low friction, secure archwire engagement and light forces can achieve

23. Commonly used SL system

24. Damon SL brackets Available in 1996 They had a slide which moved vertically on the labial surface of an otherwise fairly conventional twin tie-wing bracket . Problems: the slides inadvertently opened and were prone to breakage.

25. Damon 2 Placed the slide within the shelter of the tiewings (robust and secure) Metal injection moulding manufacture Narrower bracket with the consequent advantages of a larger inter-bracket span Disadvantages: not easy to open, and it was possible for the slide to be in a half-open position hindering archwire removal or placement.

26. Damon 3 3 major changes: A tooth-coloured composite resin base and upper tie-wing which reduces the visual impact of the bracket A rhomboidal shape of the bracket and slide which facilitates bracket siting Vertically placed chair-shaped spring clip behind the slide. Problems: H igh rate of bond failure S eparation of the metal from the reinforced resin components F ractured resin tie-wings

27. Damon 3MX brackets All-metal and have the same slide mechanism as D3. They have a vertical slot behind the archwire slot into which prefabricated click-in auxiliary hooks can be added to any bracket as required and removed. The main problem is the susceptibility of the slide mechanism to becoming jammed with calculus.

28. Damon Q brackets Easier slide mechanism. Immune to the effects of calculus accumulation. A clever feature is the reciprocal nature of the opening forces which leaves almost no net force on the tooth and the slide is opened. The brackets are also smaller in all dimensions than their predecessors and space has been found for a horizontal as well as a vertical auxiliary slot.

29. In-Ovation Brackets

30. In-Ovation Brackets

31. In-Ovation Brackets

32. 3M Unitek SmartClip brackets

33. SPEED brackets

34. Active clip or passive slide ？ High forces at early stages with active clip : With thin aligning wires smaller than 0.018" diameter, the effect of having an active clip at this early stage of treatment can be thought of as having a potentially shallower bracket slot. This will frequently produce higher forces with a given wire.

35. Active clip or passive slide ？ Better labiolingual movement with active clip : for wires > 0.018" diameter, On teeth which are in whole or in part lingual to a neighbouring tooth, the active clip will bring the tooth (or part of the tooth if rotated) to same level labiolingually to the adjacent. But with passive bracket the tooth will slightly more lingual than adjacent teeth.

36. Active clip or passive slide ？ High friction at later stage with active clip : With thick rectangular wires, An active clip places a lingually directed force on the wire in all circumstances which results in a higher friction and resistance to sliding.

37. Active clip or passive slide ？ Little contribution to torque capacity by the lingually directed forces from the active clip.

38. Active clip or passive slide ？ Aging of spring clips: Pandis et al (2007), the In-Ovation clips lost an average of 50% of their stiffness during the treatment, SPEED clips had very little change in their performance. The change is sufficient that it may have biomechanical consequences of clinical significance.

39. Clinical tips when using self-ligating brackets

40. Changing treatment mechanics Longer appointment intervals ( 8-10 weeks) for some stages of treatment (early stages and significant irregularities) due to the secure wire engagement.

41. Changing treatment mechanics More traction on lighter wires : The greater effectiveness of lighter forces and decreased loss of control reduce the adverse side effects of traction on light wires. Therefore, we can use compressed coil springs and light intermaxillary elastics from the first visit.

42. Changing treatment mechanics Separate movement of individual teeth and parallel processing due to controlled teeth movement. Eg . It sensible in some malocclusions to separately retract canines to a class 1 relationship whilst simultaneously reducing the overbite. By the time the overbite reduction permits upper incisor retraction, the canines are already class 1 but in good rotational control and the case is further advanced with anchorage conserved.

43. Bracket placement and bond-up Both maxillary and mandibular arches should be bonded at the same time and that bonding should include second molar to second molar in each arch . For severely displaced teeth, it is helpful to use a Traction Hook . Damon Q, In-Ovation and SPEED brackets have a horizontal auxiliary slot which permits a low-friction application of piggyback archwires for ectopic teeth.

44. Opening and closing There are three reasons why an archwire does not seat in the slot : There is something in the slot preventing the archwire seating The archwire is not sufficiently deflected (but can be) to seat fully in the slot The archwire cannot be deflected (too stiff) to seat fully in the slot

45. Opening and closing Remove any plaque or food debris from the slot, deflect the archwire further or choose a less stiff archwire .

46. Opening and closing Engage the wire to the bracket by using : Finger pressure Tucker Cool instrument Dental floss First close the clip, slide and then thread the aligning wire through the closed bracket before engaging the other brackets

47. Archwires Initial placement When placing the initial archwires , do not include the second molars. The patient will frequently bite an 0.014" archwire out of the second molar tubes; it is better to terminate the archwires at the first molars for the first visit and then pick up the second molars on the first nickel titanium rectangular archwires (0.018” or 0.014" x 0.025" or 0.016" x 0.025").

48. Archwires Long unsupported spans: use laceback use small tubes bonded to deciduous teeth to reduce the length of the span Sleeve

49. Archwires Prevention of ‘swivelling ’: Small sections of stainless steel tube crimped onto the archwire , anterior to the crowding and not in an inter-bracket space where the wire needs to be significantly active (reduces range of action) Flowable composite (not reliable) Turning in the ends of flexible archwires . Selective locking of individual brackets to the archwire with elastomeric Small V-shaped notches in the midline of flexible wires

50. Archwires The primary archwire sequence is as follows : 0.014" nickel titanium superelastic (or 0.013” /0.012” in very irregular arches) 0.014" x 0.025" nickel titanium superelastic 0.018" x 0.025" nickel titanium superelastic 0.019" x 0.025" stainless steel

51. Archwires Secondary archwires and wires are as follows : 0.018” nickel titanium Superelastic , this archwire is useful in cases with substantial residual irregularity or compromised periodontium as the next archwire step from the initial 0.014" nickel titanium superelastic 0.016" x 0.025" nickel titanium Superelastic , this archwire is useful in cases with little irregularity as the next archwire step from the initial 0.014" nickel titanium superelastic 0.016" x 0.022" stainless steel, Can be useful for extensive sliding of individual teeth in hypodontia cases. Gives low friction with useful rigidity 0.019" x 0.025" RCOS (reverse curve of Spee ) nickel titanium Superelastic , used for managing deep overbites in both the upper and lower arches 0.019" x 0.025" TMA, very useful for individual tooth movements at the end of treatment where archwire bends are required, especially for inclination (torque) adjustments.

52. Debonding Self-ligating brackets are often more rigid than conventional twin brackets. Bracket removal may not occur by failure of bracket adhesive interface by deformation of the bracket, but by failure of bracket adhesive interface, cohesive failure of the adhesive, failure of adhesive enamel interface or combination. Risk of enamel trauma. Best way of debonding is “squeezing” under the tiewings with conventional debonding plier without torsion force.

53. Retention Retention is no different when using self-ligation.

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