Friction –
Etiology & Management
in SWA

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INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

www.indiandentalacademy.com
One of the most common methods of translating
a tooth orthodontically - sliding mechanics.
Mesiodistal tooth movement - by...
Friction is defined as a force that retards or
resists the relative motion of two objects in
contact, and its direction is...
 Static Frictional forces - smallest force

needed to start a motion of solid surfaces
with respect to each other.
 Kine...
Several variables - directly or indirectly
contribute - friction – b/w - bracket & wire;
They are:
 Arch wire.
 Material...
 Ligation of arch wire to bracket.
 Ligature wires.
 Elastomerics.
 Bracket.






Material.
Slot width and depth...
 Orthodontic appliance.
 Interbracket distance.
 Level of bracket slots between adjacent teeth.
 Forces applied for re...
 Static frictional force = coefficient of static

friction x resultant normal force;
 Kinetic frictional force = coeffic...
Prososki etal (AJO-1991) states that surface
roughness influences friction most directly
when
 dry, unlubricated sliding ...
 Sliding mechanics- biologic tissue response

and tooth movement - applied forces overcome the friction at the bracket-wi...
 Proffit etal considers frictional resistance in

orthodontic appliance to be multifactorial,
 It is α force with which ...
 role of asperities (limited number of small spots at

the peak of surface irregularities) - contributing
factor.
 These...
 coefficient of friction is


α shear strength of the junction &



1/ α yield strength of the material.

 The interlo...
Arch wire:
 Material:
Garner et al (AJO-1986) –
found significantly larger frictional force with
beta-titanium and nitino...
SEM - SS

NiTi
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Beta - Titanium

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Drescher et al - SEM study - between diverse wire
materials.
 SS and Elgiloy - smooth surface texture,
 NiTi, TMA, - ext...
 Tidy DC - fixed appliance in vitro to simulate

tooth movement in a previously aligned arch.
 Nitinol and TMA (beta-tit...
www.indiandentalacademy.com
Kapila et al (AJO- 1990) greater magnitude and more frequent variation in
frictional forces per unit distance of bracket ...
 Archwire Dimension:
 Tidy found that wire dimension and slot size had
little effect on friction.
 Vaughan etal - The f...
 Kapila et al(AJO 1990) -

Stainless steel, Co-Cr, and ß-Ti wires ↑ bracketwire friction with increase in wire size.
Incr...
 Surface properties:
 Ryan et al- (AJO 1997) - effects of ion

implantation on the rate of tooth movement.
 ion-implant...
 Brackets:
Drescher et al -study found narrow brackets to
intensify friction by enhancing tipping
movements. This implies...
 Andreasen and Quevodo, - study to evaluate the

frictional forces in the 0.022 X 0.028” edgewise
bracket system.




...
 Tidy studied the effect of load, bracket width, slot

size, arch wire size, and material.
 The forces acting on the sur...
www.indiandentalacademy.com
 The movable bracket was fitted with a 10 mm

power arm - weights - hung –force acting at the
center of resistance of the...
www.indiandentalacademy.com
Friction α applied load and

1/ α bracket width.
The friction was greatest for narrow brackets.
Wide brackets and stainl...
 Kapila et al.- investigated –
 Frictional properties of Stainless steel (SS), cobalt-

chromium (Co-Cr), nickel-titaniu...
Vaughan et al –
 Overall friction of sintered stainless steel brackets
40% to 45% < conventional cast stainless steel
bra...
 Dickson etal- experimental polycrystalline

ceramic bracket with a SS insert and compared conventional & SS bracket.
 T...
 Madhav.M and Jyothindra Kumar compared the

frictional properties and debonding
characteristics of gold inserted slot Lu...
 Ligation.
 Edwards et al- ligation techniques - on the static

frictional resistance of stainless steel brackets and
ar...
 David etal- ( AO – 95) - static frictional resistances

between
 Teflon- coated stainless steel and clear elastomeric
l...
 Self ligation.
SPEED ApplianceSpring-loaded,
Precision, Edgewise,
Energy, and Delivery,
all of which describe
features o...
Berger (AJO – 1990) ↓ force - required to move rectangular steel or
round braided arch wires - a standard distance self-li...
 Activa brackets -fully

programmed
preadjusted brackets
that were introduced in
1986- Irwin Pletcher.
 The arch wire -r...
 Shivapuja etal (AJO1994) –

Compared three self-ligating bracket systems to
conventional SS brackets and ceramic bracket...
www.indiandentalacademy.com
 Saliva.
 Stannard et al (AJO 1986)- compared the friction
of wires under dry and wet conditions.
 artificial saliva - ...
 Baker et al – (AJO 1987)-  of force necessary

to move the teeth in a saliva medium as
compared to a dry medium.
 Kusy...
 In the dry state - coefficients of friction -  

stainless steel combinations
    beta-titanium wire combinations...
 Tselepsis et al-(AJO 1994)- investigated frictional

resistance between brackets and arch wires for –
 arch wire, brack...
Conclusion.
 Friction has been a problem for orthodontists

ever. Many efforts have been made to
increase the efficiency ...
www.indiandentalacademy.com
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Friction – etiology & management in straight wire technique /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.


Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
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Friction – etiology & management in straight wire technique /certified fixed orthodontic courses by Indian dental academy

  1. 1. Friction – Etiology & Management in SWA www.indiandentalacademy.com
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  3. 3. One of the most common methods of translating a tooth orthodontically - sliding mechanics. Mesiodistal tooth movement - by guiding a tooth along a continuous arch wire with the use of an orthodontic bracket. Disadvantage - friction - resist the movement. www.indiandentalacademy.com
  4. 4. Friction is defined as a force that retards or resists the relative motion of two objects in contact, and its direction is tangential to the common boundary of the two surfaces in contact. Frictional force - 2 sliding surfaces α to the force - surfaces are pressed together. Ffr = u × F. The value of u (the coefficient of friction) www.indiandentalacademy.com
  5. 5.  Static Frictional forces - smallest force needed to start a motion of solid surfaces with respect to each other.  Kinetic frictional force - force needed to resist the sliding motion of one solid object over another at a constant speed. www.indiandentalacademy.com
  6. 6. Several variables - directly or indirectly contribute - friction – b/w - bracket & wire; They are:  Arch wire.  Material.  Cross-sectional shape/size.  Surface texture.  Stiffness. www.indiandentalacademy.com
  7. 7.  Ligation of arch wire to bracket.  Ligature wires.  Elastomerics.  Bracket.      Material. Slot width and depth. First order bend (in-out). Second order bend (angulation). Third order bend (torque). www.indiandentalacademy.com
  8. 8.  Orthodontic appliance.  Interbracket distance.  Level of bracket slots between adjacent teeth.  Forces applied for retraction.  Intraoral variable.     Saliva. Plaque. Acquired pellicle. Corrosion. www.indiandentalacademy.com
  9. 9.  Static frictional force = coefficient of static friction x resultant normal force;  Kinetic frictional force = coefficient of kinetic friction x resultant normal force.  The coefficients of static and kinetic friction, generally having magnitudes between zero and one,  depend upon -relative roughness of the contacting surfaces. www.indiandentalacademy.com
  10. 10. Prososki etal (AJO-1991) states that surface roughness influences friction most directly when  dry, unlubricated sliding occurs or when only meager lubrication is present.  geometry of roughness,  orientation of roughness features, and  relative hardness of the two contacting surfaces. Friction tends to be highest for very rough or very smooth surfaces. www.indiandentalacademy.com
  11. 11.  Sliding mechanics- biologic tissue response and tooth movement - applied forces overcome the friction at the bracket-wire interface.  High levels of bracket-wire friction may result in  binding of the bracket  little or no tooth movement.  binding of an anterior tooth under retraction  loss of anchorage. The most desirable and ideal situation, - little or no friction - b/w bracket and wire. www.indiandentalacademy.com
  12. 12.  Proffit etal considers frictional resistance in orthodontic appliance to be multifactorial,  It is α force with which the contacting surfaces are pressed together  Affected by the nature of the surface at the interface  Independent of the apparent area of contact www.indiandentalacademy.com
  13. 13.  role of asperities (limited number of small spots at the peak of surface irregularities) - contributing factor.  These elevated areas carry the entire load between two surfaces and may undergo plastic deformation with appropriate force.  Applied load determines the true contact area. www.indiandentalacademy.com
  14. 14.  coefficient of friction is  α shear strength of the junction &  1/ α yield strength of the material.  The interlocking of large and pointed asperities or ‘plowing’ of asperities into opposing surfaces -  friction. www.indiandentalacademy.com
  15. 15. Arch wire:  Material: Garner et al (AJO-1986) – found significantly larger frictional force with beta-titanium and nitinol when compared with stainless steel. Differences in surface smoothness - account for the differences in friction. www.indiandentalacademy.com
  16. 16. SEM - SS NiTi www.indiandentalacademy.com
  17. 17. Beta - Titanium www.indiandentalacademy.com
  18. 18. Drescher et al - SEM study - between diverse wire materials.  SS and Elgiloy - smooth surface texture,  NiTi, TMA, - extensive surface roughness.  Surface texture - friction magnitude in edgewise mechanics.  Effective force has to increase by twofold (stainless steel) to sixfold (TMA) to overcome bracket-to-wire friction. www.indiandentalacademy.com
  19. 19.  Tidy DC - fixed appliance in vitro to simulate tooth movement in a previously aligned arch.  Nitinol and TMA (beta-titanium) >frictional forces -2x & 5x – of SS.  SS arch wires may be used in preference to nitinol or TMA arch wires to reduce the friction in sliding mechanics. www.indiandentalacademy.com
  20. 20. www.indiandentalacademy.com
  21. 21. Kapila et al (AJO- 1990) greater magnitude and more frequent variation in frictional forces per unit distance of bracket travel with NiTi and ß-Ti wires than with SS or Co-Cr wires.  Higher mean frictional forces - NiTi and ß-Ti wires.  surface roughness of these alloys > SS or Co-Cr in SS brackets www.indiandentalacademy.com
  22. 22.  Archwire Dimension:  Tidy found that wire dimension and slot size had little effect on friction.  Vaughan etal - The frictional forces  with   rectangular wire than with round wire, and  wire size   frictional force.  Pizzoni - friction occurring in sliding mechanics as being influenced by the bracket design, wire material and wire cross section.  He concluded that round wires have lesser friction than rectangular wires, www.indiandentalacademy.com
  23. 23.  Kapila et al(AJO 1990) - Stainless steel, Co-Cr, and ß-Ti wires ↑ bracketwire friction with increase in wire size. Increase in size of NiTi wires - no significant effect on - friction between bracket and wire – in 0.018 inch narrow single br.. www.indiandentalacademy.com
  24. 24.  Surface properties:  Ryan et al- (AJO 1997) - effects of ion implantation on the rate of tooth movement.  ion-implanted wires - > movement than their untreated counterparts.  The ion-implantation process -  stress fatigue and hardness of the material  the friction. www.indiandentalacademy.com
  25. 25.  Brackets: Drescher et al -study found narrow brackets to intensify friction by enhancing tipping movements. This implies a preference for the use of medium or wide brackets in arch-guided tooth movement, particularly in cases in which excessive mesiodistal tooth translation is required www.indiandentalacademy.com
  26. 26.  Andreasen and Quevodo, - study to evaluate the frictional forces in the 0.022 X 0.028” edgewise bracket system.    Multiple round and rectangular SS wires, brackets of three different widths, four bracket wire angulations. both wet and dry conditions  Tipping the bracket &larger wires -  friction,  Bracket width & wet and dry conditions were found to be insignificant www.indiandentalacademy.com
  27. 27.  Tidy studied the effect of load, bracket width, slot size, arch wire size, and material.  The forces acting on the surface of the tooth root were simulated by a single equivalent force acting at the center of resistance of the root. The couple produced by the two-point contact with the arch wire counters the moment of this force about the arch wire. www.indiandentalacademy.com
  28. 28. www.indiandentalacademy.com
  29. 29.  The movable bracket was fitted with a 10 mm power arm - weights - hung –force acting at the center of resistance of the tooth root. The length of the power arm - distance from the slot to the center of resistance of a typical canine tooth.  The movable bracket was suspended from the load cell of the testing machine, while the baseplate moved downward with the crosshead on which it was mounted. www.indiandentalacademy.com
  30. 30. www.indiandentalacademy.com
  31. 31. Friction α applied load and 1/ α bracket width. The friction was greatest for narrow brackets. Wide brackets and stainless steel arch wires may be used in preference to nitinol or TMA arch wires to reduce the friction in sliding mechanics. www.indiandentalacademy.com
  32. 32.  Kapila et al.- investigated –  Frictional properties of Stainless steel (SS), cobalt- chromium (Co-Cr), nickel-titanium (NiTi), and βtitanium (β -Ti) wires of several sizes were tested in narrow single (0.050-inch), medium twin (0.130inch) and wide twin (0.180-inch) stainless steel brackets in both 0.018 and 0.022-inch slots.  frictional force  - wider brackets  Due to the higher force of ligation - the greater stretching of elastic ligatures on wider brackets. www.indiandentalacademy.com
  33. 33. Vaughan et al –  Overall friction of sintered stainless steel brackets 40% to 45% < conventional cast stainless steel brackets.  Pratten et al- frictional resistance of ceramic and SS brackets + SS and NiTi wire. Ceramic brackets  frictional resistance than SS brackets when used in combination with either SS or NiTi arch wires. www.indiandentalacademy.com
  34. 34.  Dickson etal- experimental polycrystalline ceramic bracket with a SS insert and compared conventional & SS bracket.  The exptl. bracket -  frictional resistance and the ceramic bracket - 0˚ angulation. No sig. diff. between the two ceramic brackets at 10˚,  frictional resistance than SS bracket. Stainless Steel insert slot - experimental bracket behave more like a stainless steel bracket rather than a conventional ceramic bracket. www.indiandentalacademy.com
  35. 35.  Madhav.M and Jyothindra Kumar compared the frictional properties and debonding characteristics of gold inserted slot Luxi™ bracket system and stainless steel inserted Clarity™ bracket system and compared them with stainless steel Gemini™ bracket.  Metal inserted ceramic brackets - frictional properties as good as stainless steel brackets.  Luxi™ - least kinetic friction  Clarity™ bracket - highest value, of the three bracket systems evaluated for both 50 gms and 100 gms load. www.indiandentalacademy.com
  36. 36.  Ligation.  Edwards et al- ligation techniques - on the static frictional resistance of stainless steel brackets and archwires - dry and wet conditions.  No significant differences in frictional resistance were found between conventionally tied elastomeric modules and stainless steel ligatures. Teflon-coated ligatures - lowest frictional forces. www.indiandentalacademy.com
  37. 37.  David etal- ( AO – 95) - static frictional resistances between  Teflon- coated stainless steel and clear elastomeric ligatures –with   SS, polycrystalline ceramic and single crystal ceramic 0.022-inch slot brackets, SS and NiTi archwires, 0.018 inch and 0.016 × 0.022 inch.  Friction was measured in the dry state at bracket- archwire angulations of 0, 5, 10, and 15 degrees.  Teflon-coated SS ligatures - friction than elastomeric ligatures regardless of bracket type, archwire type, or bracket-archwire angulation. www.indiandentalacademy.com
  38. 38.  Self ligation. SPEED ApplianceSpring-loaded, Precision, Edgewise, Energy, and Delivery, all of which describe features of the design. www.indiandentalacademy.com
  39. 39. Berger (AJO – 1990) ↓ force - required to move rectangular steel or round braided arch wires - a standard distance self-ligation SPEED bracket < the elastomeric and the steel-tie ligated "A"-Company and American Orthodontics bracket systems. www.indiandentalacademy.com
  40. 40.  Activa brackets -fully programmed preadjusted brackets that were introduced in 1986- Irwin Pletcher.  The arch wire -retained - resilient clip retaining groove gingival to the arch wire.  The friction is < elastomeric rings and conventional brackets. www.indiandentalacademy.com
  41. 41.  Shivapuja etal (AJO1994) – Compared three self-ligating bracket systems to conventional SS brackets and ceramic brackets + polyurethane elastomeric and SS tie wire ligation.  Self-ligating bracket systems -  frictional resistance,  chairtime for arch wire removal and insertion. www.indiandentalacademy.com
  42. 42. www.indiandentalacademy.com
  43. 43.  Saliva.  Stannard et al (AJO 1986)- compared the friction of wires under dry and wet conditions.  artificial saliva -  the coefficients of friction for stainless steel, beta-titanium, and nickel-titanium compared to dry conditions.  Thought to occur from  atomic attraction among ionic species.  Water and other polar liquids -  adhesion or attraction among polar materials and  friction. www.indiandentalacademy.com
  44. 44.  Baker et al – (AJO 1987)-  of force necessary to move the teeth in a saliva medium as compared to a dry medium.  Kusy et al –(AO 1991) - coefficients of friction in the dry and wet (saliva) environment for stainless steel, cobalt-chromium, nickel titanium, and beta-titanium wires against either stainless steel or polycrystalline alumina brackets. www.indiandentalacademy.com
  45. 45.  In the dry state - coefficients of friction -   stainless steel combinations     beta-titanium wire combinations.  In the wet state, stainless steel combinations -  0.05 over the dry state. beta titanium -  50% of the values in the dry state. Attributed to the adhesive and lubricious behavior of the saliva. www.indiandentalacademy.com
  46. 46.  Tselepsis et al-(AJO 1994)- investigated frictional resistance between brackets and arch wires for –  arch wire, brackets, angulation, and lubrication.  Lubrication significantly reduced the frictional resistance (up to 60.5%) for both 0° and 10° bracket-to-arch wire angulation www.indiandentalacademy.com
  47. 47. Conclusion.  Friction has been a problem for orthodontists ever. Many efforts have been made to increase the efficiency of tooth moving mechanics by reducing or eliminating the friction, but to marginal success.  Orthodontist’s dream would be to move the teeth in a frictionless system, effortlessly & efficiently. www.indiandentalacademy.com
  48. 48. www.indiandentalacademy.com

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