archwire vibrations and stick slip behavior at bracket

8/10/2019 Archwire Vibrations and Stick Slip Behavior at Bracket

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ARCHWIRE VIBRATIONS AND

STICK SLIP BEHAVIOR AT

BRACKET ARCHWIRE

INTERFACEJOURNAL CLUB


2/27

AIM OF THE STUDY

To obtain in-vivo measurements of vibrational frequencies and amplitudes

associated with oral disturbances on orthodontic appliances and thenreplicate these ex vivo to evaluate the stick-slip behavior at bracket-archwire

interfaces by using clinically relevant tipping moments during passive and

active bracket ligation. In addition, predictive statistical modeling was applied

to the exvivo data to explore a broader range of frequencies and amplitudes

of vibration and compare potential effects between the 2 types of bracket

ligation.


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REVIEW OF LITERATURE


4/27

FORCES RELEASED DURING SLIDING

MECHANICS

WITH PASSIVE SELF-LIGATING BRACKETS

ORNONCONVENTIONAL ELASTOMERIC

LIGATURES

LORENZO FRANCHI ET AL


5/27

This study was performed in Florence and Rome, Italy

4 types of passive SLB was compared to CEL and NCEL

5 brackets of each type was aligned using 0.0215 0.028-in stainless steel wirewas used to align the brackets before fixing them with cyanoacrylate glue onto

an acrylic block. The interbracket distance was set at 8.5 mm

Sliding friction generated by the 0.019 0.025-in stainless steel wire wasmeasured under dry conditions and at room temperature (20C 2C)

Result: Significantly smaller static and kinetic forces were generated by the

SLBs and NCEL (2 g) compared with the CEL (500 g). No significant differenceswere found within the different types of SLBs, or between these and the NCEL


6/27

INFLUENCE OF ANGULATION ON THE

RESISTANCE TO SLIDING IN FIXED

APPLIANCES

LAURENCE C. ARTICOLO AND ROBERT P. KUSY


7/27

Study was performed in Chapel Hill, North Carolina

The resistances to sliding of 21 25 mil stainless steel, nickel titanium, or beta-titanium arch wires ligated to brackets made of stainless steel, single crystal

sapphire, or polycrystalline alumina with 10 mil stainless steel ligatures werestudied as a function of five angulations (0, 3, 7, 11, and 13) using ninedifferent couples .

After 22 mil brackets were mounted to fixtures and, the arch wires were slidthrough the brackets at 1 cm/minute in the dry state at 34C.

The resistance to sliding was measured by one computer while five normalforces (nominally 0.2, 0.4, 0.6, 0.8, and 1.0 kg) were serially maintained byanother computer

When couples were in the passive configuration at low angulations, allstainless steel wire-bracket couples once again had the least resistance tosliding.

When the angulation exceeded about 3, however, the active configurationemerged and binding quickly dominated as the resistance to sliding increasedover 100-fold. Under these conditions, the relative rankings among thematerials transposed; couples of stainless steel had the most resistance tosliding, whereas, couples of the more compliant alloys, such as nickel titaniumwire, had the least.


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10/27

COMPARATIVE EVALUATION OFFRICTIONAL FORCES IN ACTIVE AND

PASSIVE SELF-LIGATING BRACKETS WITH

VARIOUS ARCHWIRE ALLOYS

MANU KRISHNAN ET AL


11/27

This in-vitro study compared the effects of stainless steel, nickel-titanium, and

beta-titanium archwires on frictional forces of passive and active self-ligating

brackets with a conventional bracket

Static and kinetic frictional forces were lower for both the passive and active

designs than for the conventional brackets. Maximum values were seen with

the beta-titanium archwires, and significant differences were observed

between nickel titanium and stainless steel archwires. With the passive or

active self-ligating brackets, stainless steel wire did not produce a significant

difference, but differences were significant with nickel-titanium and beta-

titanium wires.


12/27

COMPARISON OF RESISTANCE TO

SLIDING BETWEEN DIFFERENT SELF-LIGATING BRACKETS WITH SECOND

ORDER ANGULATION IN THE DRY AND

SALIVA STATES

GLENYS A. THORSTENSON AND ROBERT P. KUSY


13/27

Resistance to sliding was investigated for 3 self-ligating brackets having passive

slides and 3 self-ligating brackets having active clips. For all cases, an 0.018

0.025-in stainless steel archwire was drawn through each bracket at a rate of10 mm/min over a distance of 2.5 mm. For each bracket, the resistances to

sliding were measured at 14 second-order angulations, which ranged from 9

to 9. Both the dry and the wet (human saliva) states were evaluated at 34C.

From dimensional measurements, the critical contact angles for binding were

determined for all products and ranged from 3 to 5.

Below each characteristic critical angle, brackets with passive slides exhibited

negligible friction; brackets with active clips exhibited frictional forces as great

as 50 cN (50 g). Above each critical angle, all brackets had elastic binding

forces that increased at similar rates as angulation increased and were

independent of bracket design. Generally speaking, at second-order

angulations that exceeded the critical angle, brackets with active clips that hada low critical angle had more resistance to sliding than did brackets with active

clips that had a higher critical angle. Brackets with passive slides that had a

high critical angle exhibited the lowest resistance to sliding, but could do so at

a cost of some loss of control.


14/27

FRICTION AND RESISTANCE TO

SLIDING IN ORTHODONTICS: A

CRITICAL REVIEW

S. JACK BURROW


15/27

Frictional resistance was effectively reduced to zero each time minute relative

movements occurred at the bracket/ wire interfaces because binding and

notching were temporarily released

Oscillating the bracket while measuring the resistance to sliding, produces the

same temporary release of binding

If one considers the clinical situation, where there is intermittent movement

between the bracket and archwire, then clinically one may not be looking at

true friction, but rather a binding and releasing phenomenon

Hixon et al observed that vibrating the teeth decreased resistance to sliding,

providing supporting evidence of movement as binding and releasing.


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TAKING THE CHATTER OUT OF SLIDING

MECHANICS - ADDRESSING THE

VIBRATION ISSUE

ROBERT P. KUSY


17/27

Although vibration might help an archwire jump out of a notched wire region

that has occurred because of excessive angulation (or torquing) or because of

inadequate yield strength (or hardness), vibration normally represents just a

lot of undeterminable wind that probably blows east as often as it does west,or north, or south. The practitioner and his or her sliding mechanics

determine the prevailing course. So, let us maintain our bearings in

understanding the principles of sliding mechanics without being too distracted

by the chatter from indefinable vibrations.


18/27

MATERIALSAND

METHODS

6 volunteers

The subjects were at least 18 years of age,

had maxillary right canines, and were

undergoing orthodontic treatment with

fixed appliances on their maxillary andmandibular anterior and posterior teeth

Single axis peizoresistive accelerometer

Digital storage oscilloscope

In-vivo

The mean vibration frequency was 98 ( 41) Hz with a range

of 58 to 139 Hz

The mean peak-to-peak vibration amplitude was 151 ( 39)

mV with a range of 112 to 190 mV


19/27

MATERIALSAND

METHODS

A waveform generator

0.017 3 0.025-in stainless steel archwire

Two types of stainless steel brackets with 0.022 3

0.028-in slot dimensions for the maxillary right canine

DamonQ, 491- 6480; Ormco, Orange, Calif had amesiodistal width of 2.9 mm and characteristics of

passive ligation by closing a door and creating atube to constrain the archwire.

Unitek Victory Series, 017-880; 3M Unitek,Monrovia, Calif had a mesiodistal width of 3.4 mm,conventional twin design, and characteristics ofactive ligation by using an elastomeric ligature

Each bracket had bonded (Transbond XT; 3M Unitek)

to its mesh pad a moment arm that was a 0.032-indiameter stainless steel wire (Dentsply GACInternational) that extended superiorly with a notch10 mm above the center of the bracket slot. Thismoment arm was perpendicular to the gingival andincisal wall of the bracket slot and parallel to thepulpal wall of the bracket slot.

Ex-vivo


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MATERIALS AND METHODS

Spring was activated 12mm

Moment per mm deactivation of spring = 1460 cN

Data and statistical analyses used backward linear regression to determine

which, if any, independent variables had no significant effect on the

dependent variable, bracket-archwire frictional resistance


22/27

RESULTS

The bench-top stick-slip measurement trials containing medium (150 mV) and high(190 mV) amplitude vibrations had significantly less friction (ln, s), 4.81 2.08 and4.67 2.00, respectively, than those subjected to low (110 mV) amplitudes, 5.80 1.39 (P = 0.04). There were no significant differences between passive and activeligation methods.

Analyses determined critical frequencies and amplitudes of vibration for thehighest values of predicted frictional resistance, which were 122 Hz (2.99) and 111mV (1.00) for the passive bracket ligation type and 120 Hz (2.27) and 100 mV (1.51)for the active bracket ligation type.

The lowest predicted frictional resistance for the range of frequencies andamplitudes investigated was for the passive bracket ligation type at 58 Hz and 202mV. In contrast, the lowest frictional resistance predicted for the active bracketligation type was at 150 Hz and 205 mV and was 5-fold higher


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0

1

2

3

4

5

6

110 150 190

5.64

4.47 4.21

5.97

5.14 5.14

MEANFRICTIONALRESISTANCE

AMPLITUDE

110 150 190

PASSIVE 5.64 4.47 4.21

ACTIVE 5.97 5.14 5.14

PASSIVE ACTIVE


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0

1

2

3

4

5

6

60 100 140

3.28

4.34 4.44.425.06 4.84

MEANFRICTIONA

LRESISTANCE

FREQUENCY

60 100 140

PASSIVE 3.28 4.34 4.4

ACTIVE 4.42 5.06 4.84

PASSIVE ACTIVE


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DISCUSSION

LIMITATIONS OF THE STUDY

BIOLOGIC FACTORS NOT CONSIDERED

DID NOT TAKE INTO ACCOUNTRHEOPHYSICS OF SALIVA, FOOD &BEVERAGES

TEMPERATURE CHANGES

CHANGES OF PHYSICAL PROPERTIES OFWIRE, ELASTOMERIC LIGATION

THE MASS OF THE ACCELEROMETERMIGHT HAVE AFFECTED ARCHWIREVIBRATION

EFFECTS OF INTERBRACKET DISTANCE ANDADJACENT TOOTH CONSTRAINTCONDITIONS WERE NOT INCLUDED

REAL-TIME RECORDING OF TRACTIONALFORCES

BROADER RANGE OF BRACKET SLOT AND

ARCHWIRE DIMENSIONS TO BE TESTED


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CONCLUSION

Further studies including all variables concerned needs to be performed for

clinically applicability


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THANK YOU

archwire vibrations and stick slip behavior at bracket

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