evaluation of the loading, unloading, and permanent...

Research ArticleEvaluation of the Loading Unloading and PermanentDeformation of Newly Available Epoxy Resin Coated Ni-Ti WiresUsing Self-Ligating Brackets

Hazel Garro-Pintildea1 Mariacutea Cristina Jimeacutenez-Cervantes2 Ricardo Ondarza-Rovira3

Roberto Justus4 and Salvador Garciacutea-Loacutepez5

1Private Practice San Jose Costa Rica2Department of Orthodontics Universidad Intercontinental Mexico City Mexico3Instituto Nacional de Investigaciones Nucleares and Universidad Intercontinental Mexico City Mexico4Universidad Intercontinental Mexico City Mexico5Universidad Intercontinental e Universidad Autonoma Metropolitana Mexico City Mexico

Correspondence should be addressed to Salvador Garcıa-Lopez drsalvadorgarcialopezgmailcom

Received 20 December 2016 Revised 3 April 2017 Accepted 27 April 2017 Published 23 May 2017

Academic Editor Carla Evans

Copyright copy 2017 Hazel Garro-Pina et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Aim The purpose of this study was to evaluate the load and unload deflection and permanent deformation of round 001610158401015840 andrectangular 001610158401015840 times 002210158401015840 regular and coatedNi-TiwiresMaterials andMethods Ni-Ti archwires produced by twomanufacturerswere evaluated Both regular and coated round and rectangular Ni-Ti wire segments (119899 = 15) from each group were submitted toa three-point bending test Both types of wires were evaluated for permanent deformation at the end of a recovery cycle ResultsThe coated round 001610158401015840 Ni-Ti wires produced a significantly lower force in loading (119901 lt 001) and unloading (119901 lt 001) thanregular wires of the samemanufacturer and sizeThere was no significant difference in permanent deformation between coated andregular round Ni-Ti wires from the same company For rectangular 0016 times 002210158401015840 Ni-Ti wires there was a significant difference inthe loading evaluation but the unloading test presented no significant differences The permanent deformation of the rectangularwires revealed no significant difference between them Conclusion The addition of an esthetic coating to these new Ni-Ti wiresproduced changes in their mechanical properties manifested as a reduction in the applied force which should be considered inclinical management

1 Introduction

Orthodontic treatment in adults has begun to seek moreesthetic orthodontic appliances Although clear brackets havebeen used worldwide for a long time [1] the archwires con-tinue to be made of metals such as stainless steel nickel tita-nium or titanium molybdenum alloy [2] Fiber-reinforcedand coated metallic wires have been developed to promotea more appealing appearance during orthodontic treatment[3] The emerging coated metallic archwires include tooth-colored polymer made of polytetrafluoroethylene or epoxyresin which is heat treated in a chamber furnace [4] This

approach improves the esthetics butmay alter themechanicalproperties of the wires Some studies have shown that thecolor tends to change with time and that the coated wiresplits duringmechanics exposing the underlyingmetal [5 6]Although the coating reduces friction with the bracket [7]further increased surface roughness can increase the frictioncoefficient [8] therefore coating stability is needed in thistype of wire to maintain a force comparable to that of mostregular Ni-Ti archwires The mechanical properties of thesetypes of wires can be assessed using 3-point bending testswhich evaluate the load and unload force deflection in thehorizontal or vertical direction allowing one to determine the

HindawiInternational Journal of DentistryVolume 2017 Article ID 8085067 8 pageshttpsdoiorg10115520178085067

2 International Journal of Dentistry

biological nature of tooth movement [9] However althoughcoated Ni-Ti archwires present certain disadvantages thiskind of wire continues to be marketed consequently newmanufacturers are available today No studies have yet beenconducted to evaluate the mechanical properties of thesenew esthetic coated fabricated archwires and to comparethem with the properties of conventional Ni-Ti wires of thesame dimensions from the same manufacturer The purposeof this study was to evaluate and compare the force levelsand permanent deflection of round 001610158401015840 and rectangular001610158401015840 times 002210158401015840 regular and coated Ni-Ti wires from threedifferent companies using self-ligating brackets under thesame testing conditions

2 Materials and Methods

Coated and regular 001610158401015840 round and rectangular 001610158401015840 times002210158401015840 Ni-Ti wires from three different manufacturers (AhKim Pech 03100 Mexico City Mexico Borgatta 15700Mexico City Mexico TP Orthodontics Inc 46350-9672 LaPorte IN USA) were selected from the same lot Both 0016-inch diameter round and 0016 times 0022-inch rectangularcross-section wires were selected for use These dimensionswere selected because they are commonly used in clinicalorthodontic treatment and are well-characterized in theorthodontic literatureThe wires were obtained directly fromthe manufacturers and are all from the same lots these weremeasured and verified with a digital micrometer (O4OO-EEP Electric Digital Caliper Orthodontic Tip OrthopliPhiladelphia Penn) A random sampling of the wires wasmeasured for each manufacturer for the coated wiresthe coating was first dissolved using methyl ethyl ketoneTherefore profiles of the wires were measured along theirrespective lengths and the averages were recorded For theround wires the TP labial surface coated wires were 001618inches the TP regular wires were 001618 inches the AhKim Pech coated wires were 001567 the Ah Kim Pechregular wires were 001612 the Borgatta coated wires were001527 and the Borgatta regular wires were 001623 For therectangular wires the TP labial surface coated was 01562times 002147 the TP regular was 0 The sample size consistedof 15 wires for both the control and experimental groupsStraight pieces of Ni-Ti wire 35mm back ends in lengthwere evaluated as previously described [10] following therecommendations with minimal modifications of the ISOstandard 15841 for the three-point bending test at 36∘C AUniversal Testing Machine INSTRON 5567 (Norwood MA02062-2643 USA) was used to evaluate the load-unload-deflection characteristics of the specimens at the Dental Bio-materials Laboratory of the National Autonomous Universityof Mexico (UNAM) where the equipment was properlycalibrated prior to testing Each sample was subjected to aloading and unloading cycle under a cell of Newtons Thetest wires were placed on a metal fixture with two-pointsupports at a distance of 14mm [11 12] Moreover in a pilotstudy it was observed that the arch tended to separate fromthe distal end of the brackets due to the deformation inthe central area Therefore to better simulate the conditions

1 mm2 mm3 mm

Figure 1 Four passive bicuspid Damon Q self-ligating brackets(Ormco Co Orange California 92867 USA) were attached to themetal base for the three-point fixture

two more brackets were attached at 8mm distal from eachplaced bracket On the surface of the metal fixture fourbicuspid passive DamonQ self-ligating brackets (Ormco CoOrange California 92867 USA) slot size 002210158401015840 times 002810158401015840were adhered Although the ISO standard 15841 recommendsstandard brackets we used these kinds of brackets becausethey have shown less friction [13] they therefore allowed usto reduce to a greater extent any unfavorable effects due tofriction by stainless steel ligatures and to avoid bias To adherethe brackets without creating deflection angles a straightsteel wire 001910158401015840 times 002510158401015840 thick was placed through the fourpreadhesion brackets and it was removed 25min after thelast bracket was placed To obtain straight portions of nickel-titanium wire the two back ends of the preformed archeswere collected [14] Segments of 35mm in length were cutand measurements were performed with a digital calibratorFor each test a segment was slid into the bracket slot so thatthe bracket lids would not open during the experiments

The test wires were secured on passive self-ligatingDamon Q bicuspid brackets slot 002210158401015840 times 002810158401015840 (OrmcoCo Orange California 92867 USA) which were attachedto the surface of the metallic fixture (Figure 1) The tipof the striker was placed at the center of the sample at7mm from the test-wire span The crosshead speed forloading and unloading was 5mmmin for the round Ni-Tiwires and the midportion of the wire was deflected Eachsample was recorded at 1 2 3 and 5mm the latter withthe purpose of obtaining further information during theexperiments and the unloading values were taken at 3 2and 1mm For the rectangular wires the crosshead speed forloading and unloading was 3mmmin the wire deflectionwas recorded at 1 2 and 3mm and the unloading valueswere evaluated at 2 and 1mm For both the round Ni-Ti wiresand the rectangular wires the permanent ldquorecoveryrdquo unloaddeflection was recorded at the end of each cycle For eachsample 2min of cycle (1min of load and 1min of discharge)was completed registering the force shown on the computerscreen at the end of the loading phase and the value graphissued by Calvarez MtMmeasurement software (Des PlainesIL 60018 USA) For each plot the force (119910-axis) was obtainedldquoby rule of threerdquo from the final value of the load registered

International Journal of Dentistry 3

Table 1 Comparison of the mean force in Newtons between the regular and coated Ni-Ti round 001610158401015840 wires at different deflection loadsThe results are expressed as the mean plusmn SEM for 15 Ni-Ti wires lowast119901 lt 001 and lowastlowast119901 lt 0001 experimental group significantly less than control

Round 001610158401015840 Loading119901 value Unloading

119901 valueMean DS SE CV Mean DS SE CV

TP Ni-Ti regular

1mm 274 019 274 7080 1mm 117 019 107 184362mm 372 029 372 6815 2mm 117 029 117 20947 lowast119901 lt 001

3mm 411 029 421 6805 3mm 078 029 068 363145mm 490 039 490 8149 5mm

TP Ni-Ti coated

1mm 274 019 274 7776 1mm 117 019 127 118852mm 392 029 402 6599 lowast119901 lt 001 2mm 156 019 166 125723mm 441 029 451 6629 lowast119901 lt 001 3mm 127 019 127 18044 lowast119901 lt 001

5mm 460 039 480 7855 5mm

Ah Kim Pech Ni-Ti regular

1mm 313 019 313 7011 1mm 117 019 117 167102mm 382 029 382 7835 2mm 107 019 107 150723mm 411 029 411 7845 3mm 166 313 088 1836985mm 451 147 451 33087 5mm

Ah Kim Pech Ni-Ti coated

1mm 235 019 235 9796 lowast119901 lt 001 1mm 107 019 098 223392mm 294 019 294 7482 lowast119901 lt 001 2mm 010 019 098 215053mm 294 029 304 8776 lowast119901 lt 001 3mm 088 019 088 22084 lowastlowast119901 lt 0001

5mm 294 029 294 9159 lowast119901 lt 001 5mm

Borgatta Ni-Ti regular


Borgatta Ni-Ti coated

1mm 304 058 294 17916 1mm 088 029 098 31528 lowast119901 lt 001

2mm 372 107 343 29057 lowast119901 lt 001 2mm 078 029 078 34833 lowast119901 lt 001

3mm 362 029 362 8776 lowast119901 lt 001 3mm 068 039 058 589475mm 382 078 362 18799 lowastlowast119901 lt 0001 5mm

for 1 2 and 3mm of deflection (119909-axis) of the sample Thefinal deformation value of thematerial wasmeasured in thosesamples in which the traced endpoint did not coincide withthe origin point (deflection 0)

All samples were tested under identical conditions Theforce deflection values were registered in a Cartesian planeThe load and unload deflection span were compared betweencoated Ni-Ti and regular wires of the same size and fromthe same manufacturer and coated Ni-Ti wires of the samedimensions were also compared among different manufac-turers

21 Statistical Analysis Data are expressed as the meanstandard error of the mean (SEM) Differences betweenthe control and experimental load and unload deflectionof the Ni-Ti regular and coated wires were determinedthrough the variance analysis offered by Fisherrsquos Test and thenonparametric Tukey test using GraphPad Prism 4 software(GraphPad Software Inc San Diego CA USA) The level ofsignificance was set at 119901 lt 005

3 Results

31 Load andUnload Evaluation of Round 001610158401015840 Ni-Ti Coatedand Regular Wires The force load and unload deflections of

the Ni-Ti wires were recorded in Newtonsforce The meanforce load and the unload deflection values of 001610158401015840 roundNi-Ti coated (119873 = 15) and regular (119873 = 15) wires arepresented in Table 1 The TP-reflex coated wires showed alower force at 2 (119901 lt 001) and 3mm (119901 lt 001) loadand unload deflection compared to the Ni-Ti regular wiresfrom the same company and the differences were significant(119901 lt 001) (Figure 2) For the Ah Kim Pech coated wiresa lower force at 1 2 3 and 5mm loading and unloading at3mm was observed compared to that of the regular Ni-Tiwires (119901 lt 001) (Figure 3) Finally compared to the controlgroup the Borgatta coated Ni-Ti wires showed a lower forceat 2 3 and 5mm loading and a lower unload deflection at 1and 2mm (119901 lt 001) (Figure 4)

32 Permanent Deflection of 001610158401015840 Round Coated and Reg-ular Wires The permanent deflection evaluated after anunload test recovery cycle showed no significant differencewhen comparing the regular and coated Ni-Ti wires from thethree testedmanufacturers (Figure 5)Nevertheless therewasa significant trend of increased permanent deflection whenthe TPNi-Ti coated wires were compared to the AhKimPechproduct (119901 lt 001) The Borgatta coated wire resulted in thehighest permanent deflection


TP Ni-Ti regularTP Ni-Ti coated

0

1

2

3

4

5

6Fo

rce (

New

tons

)

1 2 3 50

Deflection (mm)

Figure 2 Comparison of the mean force (N) load and unloaddeflection between the coated and regular Ni-Ti TP round 001610158401015840wiresThere was a statistically significant decrease in the coated wireat 2mm (119901 lt 001) and 3mm (119901 lt 001) load deflection for anunload deflection at 2mm a decrease (119901 lt 001) was observedwhile at 3mm an increase (119901 lt 001) was found compared toregular Ni-Ti wires

Ah Kim Pech coatedAh Kim Pech regular

0

05

1

15

2

25

3

35

4

45

5

Forc

e (N

ewto

ns)

1 2 3 50

Deflection (mm)

Figure 3 Comparison of the mean force (N) load and unloaddeflection between the coated and regular AhKimPech 001610158401015840 Ni-TiwiresTherewas a statistically significant difference in the coatedNi-Ti wires at 1mm (119901 lt 0001) 2mm (119901 lt 0001) 3mm (119901 lt 0001)and 5mm (119901 lt 0001) load deflection and for unload deflection at1mm (119901 lt 0001) 2mm (119901 lt 0001) and 3mm (119901 lt 0001)

Both regular and coated Borgatta archwires presented thehighest values of deformation the coated archwire had thehighest standard deviation and high values of coefficient ofvariation indicating that there was high variability in thedeformation of the wireThe regular and coated AhKimPecharchwires were the least deformed (Table 2)

33 Load and Unload Evaluation of Rectangular 001610158401015840 times002210158401015840 Ni-Ti Coated and Regular Wires Themean force loadand the unload deflection values for rectangular 001610158401015840 times002210158401015840 Ni-Ti coated and regular wires are presented inTable 3 The TP coated wires showed a significantly lowerforce at 1 (119901 lt 001) and 3 (119901 lt 001) mm loading comparedto the control group The unload deflection did not present asignificant difference comparedwithNi-Ti regular wires from

Forc

e (N

ewto

ns)

7

6

5

4

3

2

1

0

Borgatta coatedBorgatta regular

1 2 3 50

Deflection (mm)

Figure 4 Comparison of the mean force (N) load and unloaddeflection between coated and regular Borgatta 001610158401015840 Ni-Ti wiresTherewas a statistically significant decrease in the coatedNi-Ti wiresat 2mm (119901 lt 0001) 3mm (119901 lt 0001) and 5mm (119901 lt 00001)load deflection compared with regular Ni-Ti wires For the unloaddeflection the coated Ni-Ti wires showed a significantly decreaseddeflection at 1mm (119901 lt 001) and 2mm (119901 lt 001) compared withthe regular Ni-Ti wire

0

1

2

3

4

Forc

e (N

ewto

ns)

TP co

ated

Borg

atta

coat

ed

Borg

atta

regu

lar

Ah

Kim

Pec

h re

gula

r

Ah

Kim

Pec

h co

ated

TP re

gula

r

Figure 5 Comparison of the mean force (N) of the permanentdeflection between round 001610158401015840 regular and coated Ni-Ti wiresThere was no statistically significant difference between the coatedand regular Ni-Ti wires from the three manufacturers neverthelessthere was a statistically significant difference between the coated TPand the Ah Kim Pech and Borgatta Ni-Ti wires (119901 lt 001)

the same company (Figure 6) For the Ah Kim Pech coatedwires a significant differencewas observed with a lower forceat 1 (119901 lt 001) and 2 (119901 lt 001)mm loading For the unloadedgroup there was no significant difference between the coatedand regular Ni-Ti wires (Figure 7)The Borgatta coated Ni-Tiwires showed a significantly lower force at 1mm (119901 lt 001)loading For the unload deflection a significant differencewas observed at 1mm (119901 lt 0001) for the regular Ni-Ti wirescompared to the coated Ni-Ti wires (Figure 8)


Table 2 Comparisons of the mean force (N) of the permanent deflection between the coated and regular Nil-Ti wires by manufacturer

001610158401015840 round Ni-Ti Mean SD SE CVTP regular 078 039 098 42727TP coated 058 058 058 100802Ah Kim Pech regular 029 019 029 61644Ah Kim Pech coated 029 029 029 86014Borgatta regular 107 039 127 39599Borgatta coated 137 186 068 134292

Table 3 Comparison ofmean force inNewtons between the regular and coatedNi-Ti rectangular 001610158401015840 times 002210158401015840 wires at different deflectionloads The results are expressed as the mean plusmn SEM for 15 Ni-Ti wires lowast119901 lt 001 experimental group significantly less than control

001610158401015840 times 002210158401015840 Ni-Ti Loading119901 value Unloading


TP Ni-Ti regular1mm 843 039 843 4305 lowast119901 lt 001 1mm 362 029 362 66972mm 1873 068 1863 3648 2mm 500 029 500 51773mm 1873 068 1863 3648 3mm

TP Ni-Ti coated1mm 902 088 912 9296 1mm 343 068 362 191322mm 1775 137 1765 7727 2mm 500 127 568 249673mm 1775 137 1765 7727 lowast119901 lt 001 3mm

Ah Kim Pech Ni-Ti regular1mm 706 039 715 5168 1mm 147 029 156 184652mm 1363 117 1372 8355 2mm 235 039 245 147683mm 1363 117 1372 8355 3mm

Ah Kim Pech Ni-Ti coated1mm 617 058 627 9159 lowast119901 lt 001 1mm 215 186 176 857002mm 1382 215 1402 15651 lowast119901 lt 001 2mm 196 215 137 1105203mm 1382 215 1402 1382 3mm

Borgatta Ni-Ti regular1mm 843 039 833 4059 1mm 421 147 392 33793 lowast119901 lt 001

2mm 1588 107 1569 6717 2mm 480 098 500 210643mm 1588 107 1569 6717 3mm

Borgatta Ni-Ti coated1mm 755 127 774 16612 lowast119901 lt 001 1mm 245 117 245 464342mm 1500 225 1539 14935 2mm 392 147 411 377163mm 1500 225 1539 14935 3mm

34 Permanent Deformation of Rectangular 001610158401015840 times 002210158401015840Coated and Regular Wires An evaluation of the permanentdeformation after an unload test recovery cycle indicated nosignificant difference when regular and coated Ni-Ti wireswere compared for the three manufacturers tested (Figure 9)except for the coated Borgatta Ni-Ti wire which showed asignificant increase A significant difference in permanentdeformation was found when the TP Ni-Ti coated wires werecompared to the Borgatta wires (119901 lt 001) Furthermore asignificant difference was observed between the deformationof the TP-Ni-Ti coatedwire and that of the Borgatta wire (119901 lt001) (Figure 9) The Ah Kim Pech rectangular Ni-Ti coatedwire had a smaller permanent recovery cycle deformation

The Borgatta coated Ni-Ti wire segments presentedgreater permanent deflection followed by the TP labialcoated wire there was less permanent deflection for the AhKim Pech wires The Borgatta coated wires had the higheststandard deviation In general the Borgatta coated wires havehigh coefficients of variation particularly those with a loweraverage permanent deflection because many of their values

were retained at zero (median) and a few were permanentlydeflected

Statistical analysis showed that there is a statisticallysignificant difference when comparing the regular and thecoated wires of the samemanufacturer in all groups (Table 4)

4 Discussion

This study evaluated the loading unloading and permanentdeformation of two newly available epoxy resin coated Ni-Ti archwires in comparison to a wire with a labial surfacecoatingThemechanical properties of these types ofwirewereassessed with a 3-point bending test to determine whetherthere is an optimum predictable and effective orthodonticforce delivery during orthodontic mechanical treatmentAlthough the ISO standard 15841 supports a length of 10mma deflection of minus31mm head speed of 125mmmin andtemperature of 36∘C [15] we used a support length of 14mma deflection of 3 or 5mm a crosshead speed of 125mmminand a temperature of 36∘C


Table 4 Comparisons of the mean force (N) of the permanent deflection between the coated and regular Ni-Ti wires by manufacturer

Mean DS SE CVTP regular 019 029 000 179667TP coated 088 088 098 98890Ah Kim Pech regular 117 107 078 93074Ah Kim Pech coated 019 039 000 156396Borgatta regular 088 127 078 137773Borgatta coated 490 500 333 99262

TP coatedTP regular

0

2

4

6

8

10

12

14

16

18

20

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)

Figure 6 Comparison ofmean force (N) load and unload deflectionbetween the coated and regular rectangular TP Ni-Ti 001610158401015840 times002210158401015840 Ni-Ti wires There was a statistically significant increase inthe coated Ni-Ti wires at 1mm (119901 lt 001) and a decrease at 3mm(119901 lt 001) load deflection compared with the regular Ni-Ti wireThere was no statistically significant difference in unload deflection


0

2

4

6

8

10

12

14

16

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)

Figure 7 Comparison ofmean force (N) load and unload deflectionbetween the coated and regular rectangular Ah Kim Pech 001610158401015840 times002210158401015840 Ni-Ti wires There was a statistically significant decrease inthe coated Ni-Ti wires at 1mm (119901 lt 001) and 2mm (119901 lt 001)load deflection compared with the regular Ni-Ti wire There was nostatistically significant difference in the unload deflection

When epoxy resin is combined with a Ni-Ti archwire itshould ideally be combined in such a manner that the finalproduct has the same mechanical properties as the Ni-Ti


0

2

4

6

8

10

12

14

16

18

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)

Figure 8 Comparison of the mean force (N) load and unloaddeflection between the coated and regular rectangular Borgatta001610158401015840 times 002210158401015840 Ni-Ti wires There was a statistically significantdecrease in the coated Ni-Ti wires at 1mm (119901 lt 001) and 3mm(119901 lt 001) load deflection compared with the regular Ni-Ti wireThere was a statistically significant increase in the unload deflectionin the regular Ni-Ti wire at 1mm compared to that of the coated wire(119901 lt 001)

0

5

10

15

Forc

e (N

ewto

ns)

TP re

gula

r

Borg

atta

coat

ed

Borg

atta

regu

lar

TP la

bial

coat

ed

Ah

Kim

Pec

h co

ated

Ah

Kim

Pec

h re

gula

r

Figure 9 Comparison of the mean force (N) of the permanentdeflection between the rectangular 001610158401015840 times 002510158401015840 regular andcoated Ni-Ti wires There was no statistically significant differencebetween the coated and regular Ni-Ti wires from TP and Ah KimPech however for the coated Borgatta wire there was a significantincrease in the permanent deflection (119901 lt 001)


archwire without the epoxy resin although this is difficult toachieve

According to Senger and Ibe the loading section of thecurve represents the force required to engage the wire in thebracket while the unloading section of the curve representsthe forces applied to the teeth during the leveling and aligningphase of treatment thus permanent deformation of theNi-Tiarchwire must be minimized [16 17]

Our evaluation of the new Ah Kim Pech epoxy resincoated 001610158401015840 round Ni-Ti wires showed significant differ-ences in force reduction when loading at 1 2 3 and 5mm asdid the new coated Borgatta Ni-Ti wire at 3 2 and 1m forunloading force deflection Additionally significant differ-ences were found in the unloading force deflection betweenthe Ah Kim Pech wire at 3mm and the Borgatta wire at 1and 2mm and their controls as reported in previous studiesof epoxy resin coated Ni-Ti wires [17ndash19] However a forcereduction for this type of wire was present usually due to aninner reduction of the wire as the epoxy resin coat increasesthe dimensions of the archwire [20 21] Nevertheless in theinner part of these types of wires there were no significantdifferences in the size which suggests that the loading andunloading was affected by the epoxy resin cover

In this study self-ligating brackets were used (Damon Qbicuspid brackets slot 002210158401015840 times 002810158401015840 Ormco Co USA)as it has been demonstrated that modules and stainless steelligatures can increase friction [19] while it is recognizedthat this kind of bracket reduces friction during initialalignment Furthermore in these experiments four bracketswere used to support the Ni-Ti wire to avoid bends in theNi-Ti wire during the evaluation and to allow for slidingmechanics during the loading assessment [8] Nonethelessthe loading curve presented for the round 001610158401015840 Ni-Ti epoxyresin coated wires from the Ah Kim Pech and Borgattamanufacturers exhibited a lower force of deflection comparedto the regular Ni-Ti wire which is partially due to thefriction between the wire and the self-ligating brackets [22]indicating a material loss of cover in the angles of theslot brackets In contrast in the unloading curve a lowerdeflection was evident producing a complex interaction inthe loading and unloading process evaluation This resultmay be influenced by the epoxy resin on the wire whichincreases the dimensions of the wire [20 21] However therewas no significant difference in the inner part of both typesof archwires the fixation of the bracket to the base withoutmovement or the components of the alloy of the Ni-Ti wire[23] as this type of Ni-Ti is martensitically stable whichis a low-temperature metallurgical phase with a hexagonalstructure in which shape memory can be mechanically orthermally induced Therefore at the end of the permanentdeflection evaluation the two types of Ni-Ti epoxy resincoated wire recovered and returned to the harder austeniticphase although the Borgatta coated archwire had the highestpermanent deflection (137plusmn186) followed by the regularNi-Ti (107 plusmn 039) compared with the Ah Kim Pech coated wire(029 plusmn 029) and the regular Ni-Ti Archwire (029 plusmn 019)

To produce reference values of the mechanical propertiesof these new epoxy resin coated Ni-Ti wires they were

compared with the TP-reflex Ni-Ti archwires with only alabial surface covered with epoxy resin as this feature ofthe wire reduces friction A significant difference in forcereduction was found for loading at 2 and 3mm and forunloading force deflection at 2 and 3mm compared withregular Ni-Ti wiresThere was no permanent deformation foreither the coated or regular Ni-Ti wire The force deliveredby this type of Ni-Ti wire is consistent with a previousstudy that reported that the force in Newtons exceeds theideal value [8] Considering these mechanical propertiesthe Borgatta wires showed a lower force followed by theAh Kim Pech wire compared with the TP-reflex coated Ni-Ti wires Nevertheless wires from the three manufacturersdemonstrated optimal mechanical properties with respect toelasticity and resilience

The mechanical properties of the rectangular 01610158401015840 times002210158401015840 Ni-Ti epoxy resin wires from the Ah Kim Pech andBorgatta manufacturers and the TP-reflex rectangular Ni-Tilabial surface coated wires differed from those of round Ni-Tiwires There was a significant force reduction at 1 and 3mmloading while the unloading in the TP-reflex rectangularepoxy labial resin wire remained similar to that of the regularNi-Ti wire There was a significant force reduction at 1 and2mm for the Ah Kim Pech and at 1mm for the Borgatta Ni-Ti epoxy resin coated wires compared with the regular Ni-Ti wires but the Ni-Ti wires from both manufacturers wereunaffected in the unloading evaluationThemechanical prop-erties of this type of wire are consistent with those reportedin previous studies [18 19 24] which recorded an optimalforce Among the three types of Ni-Ti-epoxy resin coatedwire the Ah Kim Pech wires showed the lowest force loadingdeflection After the evaluation of the epoxy resin coated Ni-Ti archwires and using theNi-Ti polytetrafluoroethylene withonly the labial surface coated as a reference we can state thatboth types of coating produced changes in the mechanicalproperties these were exhibited as a reduction in the appliedforce In addition it was previously reported that the epoxyresin coated Ni-Ti archwires show severe deterioration andgreater surface roughness on the surface of the archwires [25]Therefore the polytetrafluoroethylene labial coated surfacemay provide more advantageous properties than the formeralthough the Ah Kim Pech coated wire also had a lowerpermanent deflection than the regular Ni-TI archwire andthe Borgatta coated Ni-Ti wire had a higher permanentdeflection than the regular one

All of the samples were tested under identical conditionsat the same temperature A limitation of this study was thatthe oral environment was not simulated and there was a lackof information on the archwires from the manufacturers

It has been shown that the epoxy resin coated nitinol hasa life of 4ndash6weeks in themouth because the oral environmentcould affect the epoxy resin Nevertheless bacterial coloniza-tion is reduced in coated wires [26] although this time couldbe sufficient for initial tooth alignment Therefore futureresearch should focus on evaluating whether low coefficientsof friction and enhanced biocompatibility are possible bymodifying the surface chemistry of the polymer withoutaffecting the resilience of the wire


From the clinical practice perspective it is of great valueto orthodontic practice for newly available orthodonticmate-rials offered by manufacturers to be evaluated to determinethe appropriate orthodontic mechanical treatment goals forpatients

5 Conclusions

Within the limitations of this study the following conclusionswere drawn

(1) The coated round 001610158401015840 and rectangular 001610158401015840 times002210158401015840 Ni-Ti wires delivered significantly lower load-ing and unloading forces than regular Ni-Ti wiresfrom the same manufacturer

(2) The permanent deformation of round 001610158401015840 andrectangular 0016 times Ni-Ti wires after an unload testrecovery cycle exhibited no significant differencebetween regular and coatedNi-Tiwires from the samemanufacturer but there was a significant differenceamong wires from the three manufacturers

Conflicts of Interest

There are no potential conflicts of interest relevant to thisarticle

References

[1] J S Russell ldquoCurrent products and practice aesthetic ortho-dontic bracketsrdquo Journal of Orthodontics vol 32 no 2 pp 146ndash163 2005

[2] T N Bartzela C Senn and A Wichelhaus ldquoLoad-deflectioncharacteristics of superelastic nickel-titanium wiresrdquoThe AngleOrthodontist vol 77 no 6 pp 991ndash998 2007

[3] F Elayyan N Silikas and D Bearn ldquoEx vivo surface andmechanical properties of coated orthodontic archwiresrdquo Euro-pean Journal of Orthodontics vol 30 no 6 pp 661ndash667 2008

[4] Z-M Huang R Gopal K Fujihara et al ldquoFabrication of a newcomposite orthodontic archwire and validation by a bridgingmicromechanics modelrdquo Biomaterials vol 24 no 17 pp 2941ndash2953 2003

[5] K M Postlethwaite ldquoAdvances in fixed appliance design anduse 1 Brackets and archwiresrdquo Dental Update vol 19 no 7 pp276ndash278 1992

[6] V DrsquoAnto R Rongo G Ametrano et al ldquoEvaluation of surfaceroughness of orthodontic wires by means of atomic forcemicroscopyrdquo Angle Orthodontist vol 82 no 5 pp 922ndash9282012

[7] P Husmann C Bourauel M Wessinger and A Jager ldquoThefrictional behavior of coated guiding archwiresrdquo Journal ofOrofacial Orthopedics vol 63 no 3 pp 199ndash211 2002

[8] U H Doshi and W A Bhad-Patil ldquoStatic frictional force andsurface roughness of various bracket and wire combinationsrdquoAmerican Journal of Orthodontics and Dentofacial Orthopedicsvol 139 no 1 pp 74ndash79 2011

[9] V Krishnan and K J Kumar ldquoMechanical properties and sur-face characteristics of three archwire alloysrdquoAngleOrthodontistvol 74 no 6 pp 825ndash831 2004

[10] F Miura M Mogi Y Ohura and H Hamanaka ldquoThe super-elastic property of the Japanese NiTi alloy wire for use inorthodonticsrdquo American Journal of Orthodontics and Dentofa-cial Orthopedics vol 90 no 1 pp 1ndash10 1986

[11] N Segal J Hell and D W Berzins ldquoInfluence of stress andphase on corrosion of a superelastic nickel-titanium orthodon-tic wirerdquo American Journal of Orthodontics and DentofacialOrthopedics vol 135 no 6 pp 764ndash770 2009

[12] H Nakano K Satoh R Norris et al ldquoMechanical properties ofseveral nickel-titaniumalloywires in three-point bending testsrdquoAmerican Journal of Orthodontics and Dentofacial Orthopedicsvol 115 no 4 pp 390ndash395 1999

[13] S Aksakalli and S Malkoc ldquoEsthetic orthodontic archwiresliterature reviewrdquo Journal of Orthodontic Research vol 1 no 1pp 2ndash4 2013

[14] E F Harris S M Newman and J A Nicholson ldquoNitinol archwire in a simulated oral environment Changes in mechanicalpropertiesrdquo American Journal of Orthodontics and DentofacialOrthopedics vol 93 no 6 pp 508ndash513 1988

[15] B Washington C A Evans G Viana A Bedran-Russo and SMegremis ldquoContemporary esthetic nickel-titanium wires dothey deliver the same forcesrdquo Angle Orthodontist vol 85 no1 pp 95ndash101 2015

[16] D Segner and D Ibe ldquoProperties of superelastic wires andtheir relevance to orthodontic treatmentrdquo European Journal ofOrthodontics vol 17 no 5 pp 395ndash402 1995

[17] R P Kusy ldquoA review of contemporary archwires their proper-ties and characteristicsrdquo Angle Orthodontist vol 67 no 3 pp197ndash207 1997

[18] A A Kaphoor and S Sundareswaran ldquoAesthetic nickel tita-nium wiresmdashHow much do they deliverrdquo European Journal ofOrthodontics vol 34 no 5 pp 603ndash609 2012

[19] F Elayyan N Silikas and D Bearn ldquoMechanical properties ofcoated superelastic archwires in conventional and self-ligatingorthodontic bracketsrdquo American Journal of Orthodontics andDentofacial Orthopedics vol 137 no 2 pp 213ndash217 2010

[20] C J Burstone ldquoVariable-modulus orthodonticsrdquo AmericanJournal of Orthodontics vol 80 no 1 pp 1ndash16 1981

[21] R P Kusy ldquoOn the use of nomograms to determine the elasticproperty ratios of orthodontic arch wiresrdquo American Journal ofOrthodontics vol 83 no 5 pp 374ndash381 1983

[22] S P Henao and R P Kusy ldquoFrictional evaluations of dentaltypodont models using four self-ligating designs and a conven-tional designrdquoAngle Orthodontist vol 75 no 1 pp 75ndash85 2005

[23] M Murayama Y Namura T Tamura H Iwai and N ShimizuldquoRelationship between friction force and orthodontic force atthe leveling stage using a coated wirerdquo Journal of Applied OralScience vol 21 no 6 pp 554ndash559 2013

[24] A Wichelhaus M Geserick R Hibst and F G Sander ldquoTheeffect of surface treatment and clinical use on friction in NiTiorthodonticwiresrdquoDentalMaterials vol 21 no 10 pp 938ndash9452005

[25] D L da Silva C T Mattos R A Simao and A C D O deOliveira Ruellas ldquoCoating stability and surface characteristicsof esthetic orthodontic coated archwiresrdquo Angle Orthodontistvol 83 no 6 pp 994ndash1001 2013

[26] T Maetani R Miyoshi Y Nahara Y Kawazoe and T HamadaldquoPlaque accumulation on Teflon-coated metalrdquo The Journal ofProsthetic Dentistry vol 51 no 3 pp 353ndash357 1984

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Oral OncologyJournal of

DentistryInternational Journal of



International Journal of

Biomaterials


BioMed Research International


Case Reports in Dentistry


Oral ImplantsJournal of


Anesthesiology Research and Practice


Radiology Research and Practice

Environmental and Public Health

Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Dental SurgeryJournal of

Drug DeliveryJournal of



Oral DiseasesJournal of


Computational and Mathematical Methods in Medicine

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Preventive MedicineAdvances in


EndocrinologyInternational Journal of



OrthopedicsAdvances in


biological nature of tooth movement [9] However althoughcoated Ni-Ti archwires present certain disadvantages thiskind of wire continues to be marketed consequently newmanufacturers are available today No studies have yet beenconducted to evaluate the mechanical properties of thesenew esthetic coated fabricated archwires and to comparethem with the properties of conventional Ni-Ti wires of thesame dimensions from the same manufacturer The purposeof this study was to evaluate and compare the force levelsand permanent deflection of round 001610158401015840 and rectangular001610158401015840 times 002210158401015840 regular and coated Ni-Ti wires from threedifferent companies using self-ligating brackets under thesame testing conditions

2 Materials and Methods

Coated and regular 001610158401015840 round and rectangular 001610158401015840 times002210158401015840 Ni-Ti wires from three different manufacturers (AhKim Pech 03100 Mexico City Mexico Borgatta 15700Mexico City Mexico TP Orthodontics Inc 46350-9672 LaPorte IN USA) were selected from the same lot Both 0016-inch diameter round and 0016 times 0022-inch rectangularcross-section wires were selected for use These dimensionswere selected because they are commonly used in clinicalorthodontic treatment and are well-characterized in theorthodontic literatureThe wires were obtained directly fromthe manufacturers and are all from the same lots these weremeasured and verified with a digital micrometer (O4OO-EEP Electric Digital Caliper Orthodontic Tip OrthopliPhiladelphia Penn) A random sampling of the wires wasmeasured for each manufacturer for the coated wiresthe coating was first dissolved using methyl ethyl ketoneTherefore profiles of the wires were measured along theirrespective lengths and the averages were recorded For theround wires the TP labial surface coated wires were 001618inches the TP regular wires were 001618 inches the AhKim Pech coated wires were 001567 the Ah Kim Pechregular wires were 001612 the Borgatta coated wires were001527 and the Borgatta regular wires were 001623 For therectangular wires the TP labial surface coated was 01562times 002147 the TP regular was 0 The sample size consistedof 15 wires for both the control and experimental groupsStraight pieces of Ni-Ti wire 35mm back ends in lengthwere evaluated as previously described [10] following therecommendations with minimal modifications of the ISOstandard 15841 for the three-point bending test at 36∘C AUniversal Testing Machine INSTRON 5567 (Norwood MA02062-2643 USA) was used to evaluate the load-unload-deflection characteristics of the specimens at the Dental Bio-materials Laboratory of the National Autonomous Universityof Mexico (UNAM) where the equipment was properlycalibrated prior to testing Each sample was subjected to aloading and unloading cycle under a cell of Newtons Thetest wires were placed on a metal fixture with two-pointsupports at a distance of 14mm [11 12] Moreover in a pilotstudy it was observed that the arch tended to separate fromthe distal end of the brackets due to the deformation inthe central area Therefore to better simulate the conditions

1 mm2 mm3 mm

Figure 1 Four passive bicuspid Damon Q self-ligating brackets(Ormco Co Orange California 92867 USA) were attached to themetal base for the three-point fixture

two more brackets were attached at 8mm distal from eachplaced bracket On the surface of the metal fixture fourbicuspid passive DamonQ self-ligating brackets (Ormco CoOrange California 92867 USA) slot size 002210158401015840 times 002810158401015840were adhered Although the ISO standard 15841 recommendsstandard brackets we used these kinds of brackets becausethey have shown less friction [13] they therefore allowed usto reduce to a greater extent any unfavorable effects due tofriction by stainless steel ligatures and to avoid bias To adherethe brackets without creating deflection angles a straightsteel wire 001910158401015840 times 002510158401015840 thick was placed through the fourpreadhesion brackets and it was removed 25min after thelast bracket was placed To obtain straight portions of nickel-titanium wire the two back ends of the preformed archeswere collected [14] Segments of 35mm in length were cutand measurements were performed with a digital calibratorFor each test a segment was slid into the bracket slot so thatthe bracket lids would not open during the experiments

The test wires were secured on passive self-ligatingDamon Q bicuspid brackets slot 002210158401015840 times 002810158401015840 (OrmcoCo Orange California 92867 USA) which were attachedto the surface of the metallic fixture (Figure 1) The tipof the striker was placed at the center of the sample at7mm from the test-wire span The crosshead speed forloading and unloading was 5mmmin for the round Ni-Tiwires and the midportion of the wire was deflected Eachsample was recorded at 1 2 3 and 5mm the latter withthe purpose of obtaining further information during theexperiments and the unloading values were taken at 3 2and 1mm For the rectangular wires the crosshead speed forloading and unloading was 3mmmin the wire deflectionwas recorded at 1 2 and 3mm and the unloading valueswere evaluated at 2 and 1mm For both the round Ni-Ti wiresand the rectangular wires the permanent ldquorecoveryrdquo unloaddeflection was recorded at the end of each cycle For eachsample 2min of cycle (1min of load and 1min of discharge)was completed registering the force shown on the computerscreen at the end of the loading phase and the value graphissued by Calvarez MtMmeasurement software (Des PlainesIL 60018 USA) For each plot the force (119910-axis) was obtainedldquoby rule of threerdquo from the final value of the load registered





TP Ni-Ti regular


3mm 411 029 421 6805 3mm 078 029 068 363145mm 490 039 490 8149 5mm

TP Ni-Ti coated


5mm 460 039 480 7855 5mm





5mm 294 029 294 9159 lowast119901 lt 001 5mm




1mm 304 058 294 17916 1mm 088 029 098 31528 lowast119901 lt 001






3 Results






0

1

2

3

4

5

6Fo

rce (

New

tons

)

1 2 3 50

Deflection (mm)



0

05

1

15

2

25

3

35

4

45

5

Forc

e (N

ewto

ns)

1 2 3 50

Deflection (mm)




Forc

e (N

ewto

ns)

7

6

5

4

3

2

1

0


1 2 3 50

Deflection (mm)


0

1

2

3

4

Forc

e (N

ewto

ns)

TP co

ated

Borg

atta

coat

ed

Borg

atta

regu

lar

Ah

Kim

Pec

h re

gula

r

Ah

Kim

Pec

h co

ated

TP re

gula

r














2mm 1588 107 1569 6717 2mm 480 098 500 210643mm 1588 107 1569 6717 3mm






4 Discussion





TP coatedTP regular

0

2

4

6

8

10

12

14

16

18

20

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)



0

2

4

6

8

10

12

14

16

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)




0

2

4

6

8

10

12

14

16

18

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)


0

5

10

15

Forc

e (N

ewto

ns)

TP re

gula

r

Borg

atta

coat

ed

Borg

atta

regu

lar

TP la

bial

coat

ed

Ah

Kim

Pec

h co

ated

Ah

Kim

Pec

h re

gula

r














5 Conclusions






References


































Biomaterials












Journal of























TP Ni-Ti regular


3mm 411 029 421 6805 3mm 078 029 068 363145mm 490 039 490 8149 5mm

TP Ni-Ti coated


5mm 460 039 480 7855 5mm





5mm 294 029 294 9159 lowast119901 lt 001 5mm




1mm 304 058 294 17916 1mm 088 029 098 31528 lowast119901 lt 001






3 Results






0

1

2

3

4

5

6Fo

rce (

New

tons

)

1 2 3 50

Deflection (mm)



0

05

1

15

2

25

3

35

4

45

5

Forc

e (N

ewto

ns)

1 2 3 50

Deflection (mm)




Forc

e (N

ewto

ns)

7

6

5

4

3

2

1

0


1 2 3 50

Deflection (mm)


0

1

2

3

4

Forc

e (N

ewto

ns)

TP co

ated

Borg

atta

coat

ed

Borg

atta

regu

lar

Ah

Kim

Pec

h re

gula

r

Ah

Kim

Pec

h co

ated

TP re

gula

r














2mm 1588 107 1569 6717 2mm 480 098 500 210643mm 1588 107 1569 6717 3mm






4 Discussion





TP coatedTP regular

0

2

4

6

8

10

12

14

16

18

20

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)



0

2

4

6

8

10

12

14

16

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)




0

2

4

6

8

10

12

14

16

18

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)


0

5

10

15

Forc

e (N

ewto

ns)

TP re

gula

r

Borg

atta

coat

ed

Borg

atta

regu

lar

TP la

bial

coat

ed

Ah

Kim

Pec

h co

ated

Ah

Kim

Pec

h re

gula

r














5 Conclusions






References


































Biomaterials












Journal of





















0

1

2

3

4

5

6Fo

rce (

New

tons

)

1 2 3 50

Deflection (mm)



0

05

1

15

2

25

3

35

4

45

5

Forc

e (N

ewto

ns)

1 2 3 50

Deflection (mm)




Forc

e (N

ewto

ns)

7

6

5

4

3

2

1

0


1 2 3 50

Deflection (mm)


0

1

2

3

4

Forc

e (N

ewto

ns)

TP co

ated

Borg

atta

coat

ed

Borg

atta

regu

lar

Ah

Kim

Pec

h re

gula

r

Ah

Kim

Pec

h co

ated

TP re

gula

r














2mm 1588 107 1569 6717 2mm 480 098 500 210643mm 1588 107 1569 6717 3mm






4 Discussion





TP coatedTP regular

0

2

4

6

8

10

12

14

16

18

20

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)



0

2

4

6

8

10

12

14

16

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)




0

2

4

6

8

10

12

14

16

18

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)


0

5

10

15

Forc

e (N

ewto

ns)

TP re

gula

r

Borg

atta

coat

ed

Borg

atta

regu

lar

TP la

bial

coat

ed

Ah

Kim

Pec

h co

ated

Ah

Kim

Pec

h re

gula

r














5 Conclusions






References


































Biomaterials












Journal of






























2mm 1588 107 1569 6717 2mm 480 098 500 210643mm 1588 107 1569 6717 3mm






4 Discussion





TP coatedTP regular

0

2

4

6

8

10

12

14

16

18

20

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)



0

2

4

6

8

10

12

14

16

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)




0

2

4

6

8

10

12

14

16

18

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)


0

5

10

15

Forc

e (N

ewto

ns)

TP re

gula

r

Borg

atta

coat

ed

Borg

atta

regu

lar

TP la

bial

coat

ed

Ah

Kim

Pec

h co

ated

Ah

Kim

Pec

h re

gula

r














5 Conclusions






References


































Biomaterials












Journal of






















TP coatedTP regular

0

2

4

6

8

10

12

14

16

18

20

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)



0

2

4

6

8

10

12

14

16

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)




0

2

4

6

8

10

12

14

16

18

Forc

e (N

ewto

ns)

1 2 30

Deflection (mm)


0

5

10

15

Forc

e (N

ewto

ns)

TP re

gula

r

Borg

atta

coat

ed

Borg

atta

regu

lar

TP la

bial

coat

ed

Ah

Kim

Pec

h co

ated

Ah

Kim

Pec

h re

gula

r














5 Conclusions






References


































Biomaterials












Journal of































5 Conclusions






References


































Biomaterials












Journal of


























Biomaterials












Journal of



















evaluation of the loading, unloading, and permanent...

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