Elastomeric ligatures final. Prof. maher fouda

transcript

Methods of LigationProf. Dr

Elastomeric Ligatures -1-

Ligatures are used to tie the archwire to the bracket. The archwire

fits into the slot in the bracket and the ligature goes around the wings of the bracket to hold the archwire in place

Elastomeric ligatures

O-Tie elastics act like bungee cords- they

cause friction and pressure, by holding the

wires tight into the bracket. This makes

treatment slower and less comfortable. The

rubber ties also absorb plaque and bacteria.

Elastomeric ligatures

Effect of Ligation Technique on Friction : • The normal force

exerted by the ligature has a significant influence in determining

the frictional resistance developed within an orthodontic system.

This force has been estimated to be between 50-300g, and upto

375g in one study. • Various methods of ligation are available: -

stainless steel ligatures, elastomeric modules, polymeric coated

modules and finally the self ligating brackets, which may be

having a spring clip (Hanson SPEED and Adenta Time) which

pushes the wire into place, or it may have a passive clip which

does not press on the wire (Activa and Damon II brackets.)

There is a large body of literature to demonstrate the much higher

friction between bracket and archwire with elastomeric ligation

compared with wire ligatures

Elastomeric Ligatures

Elastomeric ligatures are adversely affected by the oral environment,

and demonstrate stress relaxation with time and great individual

variation in properties. • Stainless steel ligatures can be tied too tight

or too loose depending on the clinicians technique. • Self ligating

brackets with a passive clip have been shown to generate negligible friction

Edwards et al (BJO 1995) compared the frictional forces produced

when elastomeric modules were applied conventionally or in a

“figure of –8” configuration, stainless steel ties or Teflon coated

ligatures were used for archwire ligation. The “figure of 8” modules

appeared to create the highest friction. There was no significant

difference in mean frictional force between the conventional module

and the SS ligature, but the Teflon coated ligature had the lowest mean frictional force. •.

Dowling et al (BJO 1998) investigated the frictional forces

of differently colored modules & found the clear modules

to exhibit significantly lower friction than other modules. This study however was carried out in absence of saliva

Khambay et al (EJO 2004) compared the effect of elastomeric type and

stainless steel ligation on frictional resistance and these were further

compared with self ligating Damon II brackets. There was no consistent pattern

in the mean frictional forces across the various combinations of wire size,

type, and ligation method. The polymeric coated module did not produce the

lowest mean frictional force. The introduction of a 45 bend into the module

(Alastik Easy-to-use) reduced mean frictional force to that of a SS ligature

when using 19 x 25” SS wire. The use of metal ligatures with 7 turns produced

the lowest friction confirming the findings of Bazakidon et al (AJO-DO 97).

They concluded that the use of passive self ligating brackets is the only way of almost eliminating friction

Slide Low

Friction

ligatures

Lam et al., reported substantial variation in the range and

tensile strength of elastomerics from different

manufacturers and for different colors of elastomeric from

the same manufacturer

Zachrisson and Zachrisson stated the etiology and pathogenesis of periodontal diseases are multifactorial, but dental plaque certainly is an essential precursor. The presence of elastomeric modules and stainless steel ligatures are taken into account for microbial dental plaque retention which causes enamel demineralization due to decrease in pH level caused by increase in number of acid-producing bacteria, mainly Streptococcus mutans and lactobacilli, which ultimately results in appearance of white spots and caries in approximately 50% of patients undergoing fixed orthodontic treatment.

Mosquito forceps are used for placing elastic ligatures and

tightening the ligature wire around brackets. It is available

in straight and curved (45 ˚)end pattern. Beaks are serrated

for better grasp.

For elastic ligation and usage.

Mosquito forceps

For elastic ligation. The tips are made so small to pick up the elastic at ease and usage.

Steps of ligation

Elastomeric ligatures became available in the late 1960s and

rapidly became the most common means of ligation, almost

entirely because of the greatly reduced time required to place

and remove them when compared with steel wire ligatures

Steel ligature

It was also easier to learn the skills required to place these

ligatures, so new clinicians and staff greatly preferred

elastomerics .

Initially these elastic bands were made from natural rubber,

but production of elastomeric chains and ligatures followed

the ability to produce synthetic elastics from polyester or

polyether urethanes.

Steps of ligation

The ease of use and speed of placement of elastomerics

ligatures did, however, lead to other definite

disadvantages being generally overlooked, although

readily apparent. Elastomerics frequently fail to fully

engage an arch wire when full engagement is intended.

Twin brackets with the ability to “figure-of-eight” the

elastomerics are a significant help in this respect but at

the cost of greatly increased friction

B: elastomeric ties (Sani-ties GAC) (O-ring); c: GAC figure-of-eight elastomeric ties;

Khambay et al. quantified

the potential seating forces

with wire and elastic

ligatures and clearly

showed the much higher

archwire seating forces

available with tight wire

ligatures.

A well-documented drawback with elastomerics

is the substantial degradation of their

mechanical properties in the oral environment.

Typically elastomeric chains and ligatures undergo

greater than 50% degradation in force in the first 24

hours when tested under in vitro experimental

environments.

Elastomeric o ties cause loss of rotational control of

canines during space closure. Twin brackets with the

ability to “figure-of-eight” the elastomerics are

indicted in this situation

Loss of arch wire controlwith elastomeric ligation.

Interestingly, friction proposed as a factor of clinical significance

more than 30 years ago but was largely disregarded until more

recently. The great popularity of elastomeric ligation in the last 40

years was achieved despite these substantial deficiencies in relation

to wire ligatures.

Elastic Ties• Once the arch wire has been positioned it must be ligated

into place, the elastic ties stretch around the bracket to

hold the arch wire in place. They come in different colors

• Use the Hemostat to place the elastic ties and the

orthodontic scaler to remove them

Speed and ease of use were the overriding assets of elastomerics, and it is no surprise that the strongest motivation behind the early efforts to produce a satisfactory self-ligating bracket was a desire to have all the benefits of wire ligation but in addition to have a system that was quick and easy to use.

With wider bracket the elasomericligature was stretched more than with a narrow bracket, producing almost twice as much friction, due to greater normal force exerted on the wire

B: elastomeric ties (Sani-ties GAC) (O-ring); c: GAC figure-of-eight elastomeric ties;

Figure 8 elastic tie•Works in horizontal and vertical orientation. Use vertical 8’s to allow easier M-D movement –less friction- and horizontal 8’s when M-D achieved to help lock in that spacing –greater friction.

Elastomeric

Ligatures

Figure 8 quick start

• Figure 8’s come in 3 sizes, small, medium and large. Choose appropriate size for ligation based on the bracket size \ central, lower anterior, etc.\ as well as how much force is required on that specific bracket. Make sure the figure 8 is secured beneath tie-wing . Since brackets come in many shapes and sizes it is up to the practitioner to judge the fit is correct to remain in place until the next office visit.

The placing of ‘figure-of-eight’ elastomeric ties increased friction by a factor of 70-220 per cent compared to the

O” elastomeric ties

Alternatively, the clinician may choose to use the elastic figure-8 technique, in which the O-ring criss-crosses over the bracket (B). Twist - ing the O-ring in this manner increases its elastic tension, which helps seat the archwire, but because the force levels of the O-ring are symmetrical, they may still be inadequate to fully seat the wire

Asymmetrical O-Ring Ligation

Traditional elastic O-ring ligation with twin brackets often fails to correct severe malrotations because of the inability to fully seat the archwire into the bracket slot (A). The clinician is faced with the decision whether to step down to a lighter nickel titanium wire or conventionally ligate the wire to the tooth, which is time-consuming and technique-sensitive and may result in de - bonding

A method of asymmetrical O-ring ligation that is a slight modification of the elastic figure-8 is used (C): 1. On the side opposite the rotation, pull the Oring over the two vertical tie wings. 2. Pull the O-ring under the incisal tie wing on the rotation side. The O-ring should now seat over the two vertical tie wings on the side away from the rotation.

3. Pull the O-ring under one vertical tie wing on the rotation side (this step distinguishes the asymmetrical tie from the figure-8 tie). 4. Wrap the O-ring over the other vertical tie wing on the rotation side. By stretching the Oring behind the tie wing, rather than crossing over the bracket slot, an asymmetrical force load is created to help fully seat the archwire into the bracket slot.

Alternatively, the clinician may choose to use the elastic figure-8 technique, in which the O-ring criss-crosses over the bracket (B). Twist - ing the O-ring in this manner increases its elastic tension, which helps seat the archwire, but because the force levels of the O-ring are symmetrical, they may still be inadequate to fully seat the wire

AlastiK ™ Easy-To-Tie LigaturesAlastiK™ Easy-To-Tie Ligatures are designed with a 45˚ bend which makes tie-wing hook-up easier and more efficient than ever before. The unique angled shape reduces the range of movement needed for bracket ligation, improving the entire process for you and the patient. With less contact of the placement tool with the patient’s lips, patient comfort is enhanced.

Elastomeric Ligature with Guard

• Not Made With Natural Rubber Latex • .124 in. (3.1 mm) outer diameter • Reduces tooth contact with ceramic brackets on mandibular teeth • Injection molded memory material

A comparative study of the physical and elastic properties of new generation elastomeric ligatures with conventional elastomeric ligatures

Journal of Dr. NTR University of Health Sciences 2015;4(2) 91-96

Four groups of clear elastomeric modules (inside diameter 1.3 mm, outside diameter 3.1 mm, thickness 0.9 mm) were evaluated and compared in this study [Figure 1]. The first group (CO) comprised of the conventional polyurethane-based elastomeric modules obtained from Millenium Orthodontics, New Delhi, India. The second group (LF) constituted the latex free elastomeric modules obtained from Desires Orthodontics, Davangere, India. The third group (AL) comprised of Alastik™ Easy-to-tie modules (with 45° bend) obtained from 3M Unitek, Monrovia, CA, USA. The fourth group (SL) constituted the super ligatures which were silver and silicone impregnated obtained from D-tech, Pune, India

CONCLUSION The decrease in tensile properties of elastomeric ligatures shows that they may have to be replaced at each appointment to reduce the risk of rupture.

There are signifi cant differences in tensile properties of different brands of ligatures, which should be considered during the selection of these products. Considering the number of variables evaluated in this study, it is difficult to conclude about the best elastomeric ligature from the point of physical and elastic properties. It is also suggested that manufacturers offer the relevant data to their customers in order to facilitate the selection of appropriate elastomeric ligatures as per their clinical demands.

Space closure by elastomeric module with ligature wire is better than the E-chain.

During space closure procedure two different retracting components were applied in right and left sides of each case. On right side elastic chain (E-chain) applied in both upper and lower arches and on left side elastomeric module with steel ligature (0.010″) stretched double its diameter fixed in both arches

bimaxillary dentoalveolar protrusion; elastic chain; elastomeric module with ligature

Retraction with elastomeric chain. Retraction with elastic module.

A comparative evaluation of rate of space closure after extraction using E-chain and stretched modules in bimaxillary dentoalveolar protrusion cases

Retraction with elastomeric chain. Retraction with elastic module.

To facilitate tying of retracting component anteriorly, a small piece of 0.019″ ×0.025″ wire was shaped as “S” and welded to the base arch wire in all four quadrants immediately

distal to canines. This “S”-shaped wire was ligated by the force delivery system in all the four quadrants with molar hooks.

Slide* ligatures

Leone offers elastics manufactured with the best quality of latex available. The innovative low friction Slide* ligatures are manufactured in a special medical grade polyurethane mix providing all the advantage of low friction biomechanical properties with shorter therapeutic times and without the need of extractions. These ligatures are especially indicated for use with Logic Line brackets. Leone modules for ligatures are stamped from elastomer offering the best elasticity and resistance to oral liquid absorption. Leone wires for metal ligatures are manufactured out from a high vacuum annealed alloy for the best fit and higher mechanical load.

Slide* ligatures

A new low force ligation system – jco 2005-

• This article describes an alternative to self ligating system a ligature that markedly reduced the friction b/w the Arche wire and bracket.

• The slide ligature wire is made of special polyurethane, is applied in the same way as conventional as a elastomeric ligature .

• Like a passive self ligating it forms a fourth wall and allow archewires to slide freely in the slot while transmitting its full force to the teeth.

This ligature also forms the buffer b/w the bracket and soft

tissues considerably improving patient comfort.

A new low force ligation system – jco 2005-

If high friction is demanding, conventional brackets tied with elastomeric ligatures may be used. If low friction is required, it is possible to use low friction ligatures, such as Slide ligatures (Leone, Florence, Italy)

The new Slide low friction ligatures AQUA are not subject to corrosion by oral liquids and are now even more resistant to discoloration (a recurring issue with transparent elastomers). Changing ligatures frequently is no longer necessary and perfect aesthetics is guaranteed. This ligature is indicated for use with logic line aesthetic brackets which are featuring a housing to keep Slide ligature in place for the integration in the bracket’s profile. Clear color.

Slide AQUA low friction ligatures

Ligatures: Conventional elastomeric ligature (CEL) (Leone)

Slide ligation also showed lower friction with different archwires combinations.

Frictional force released during sliding mechanics in nonconventional elastomerics and self-ligation: An in vitro comparative study

Elastomeric ligatures final. Prof. maher fouda

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