10.59987/ads/2013.2.204-211
This article is a presentation of a clinical methodology aimed at minimizing binding in fixed orthodontic appliances. The dynforce archwire is explained. The dynforce archwire has a full size anterior segment (e.g. .021x.025) and undersized posterior segments with rectangular cross-section (e.g. .018x.025 or .018x.022), and is used in the orthodontic phase of space closure with or without TAD miniscrews. Two clinical cases are presented.
application/pdf
1971-1441
142
2
en
G. Siciliani 
https://creativecommons.org/licenses/by-nc-nd/4.0
Annali di stomatologia
ceramic brackets
The dynforce archwire
Text.Serial.Journal
https://www.annalidistomatologia.eu/ads
4
Original Article
2022-08-16
2022-08-16
2013-06-01
2023-12-04
204-211
Ann Stomatol (Roma)
G. Siciliani 
2013
10.59987/ads/2013.2.204-211
204
1971-1441
2
ceramic brackets
en
211
The dynforce archwire
https://www.annalidistomatologia.eu/ads/article/download/142/125
4
6-Cantarella_- 19/06/13 10:37 Pagina 204




                                                                                                                         Original article



                   The dynforce archwire




                                                                                                                                            li
                                                                                     na
                   Daniele Cantarella                                            Orthodontic archwires are made of different alloys, like
                   Luca Lombardo                                                 stainless steel, nichel-titanium, beta-titanium, and oth-




                                                                                   io
                   Giuseppe Siciliani                                            ers. The physical features of orthodontic archwires are
                                                                                 expressed in the stress-strain or load-deflection dia-
                   Postgraduate School of Orthodontics,                          gram (1, 2) as shown in Figure 2.
                   Ferrara University, Italy                                     Orthodontic archwires have an elastic behavior. When




                                                                                az
                                                                                 the wire is deflected, it gives back a force of response
                                                                                 (Figs. 1, 2). Linear deflection is expressed by “d” in
                   Corresponding author:                                         Figure 1. The force of response depends on the rigidi-
                   Daniele Cantarella                                            ty of the archwire, represented by the slope of the




                                                                             rn
                   Postgraduate School of Orthodontics                           curve represented in Figure 2. Archwires with higher
                   Ferrara University                                            rigidity have a more vertical slope. Archwires with low-
                   Via Montebello 31                                             er rigidity (higher flexibility) have a more horizontal
                                                                                 slope.




                                                                          te
                   44121 Ferrara, Italy
                   Phone: (+39) 0532-202528                                      The diagram (Fig. 2) is also useful to understand the
                   E-mail: danielecant@hotmail.com                               resilience of the archwires. The resilience is defined as
                                                                                 the area under the load-deflection curve out to the pro-

                   Summary
                                                                       In        portional limit. It represents the energy storage capacity
                                                                                 of the wire (1). In other words it is the energy that a wire

                   This article is a presentation of a clinical methodology
                   aimed at minimizing binding in fixed orthodontic ap-
                                                          ni
                   pliances. The dynforce archwire is explained. The
                   dynforce archwire has a full size anterior segment
                   (e.g. .021x.025) and undersized posterior segments
                   with rectangular cross-section (e.g. .018x.025 or
                                            o

                   .018x.022), and is used in the orthodontic phase of
                   space closure with or without TAD miniscrews. Two
                                        izi


                   clinical cases are presented.

                   Key words: archwire, binding, friction, incisor,
                   torque, sliding, retraction, miniscrew, TAD, skeletal
                          Ed




                   anchorage, ceramic brackets.

                                                                                 Figure 1. Deflection (d) of a beam of orthodontic wire of
                   Introduction                                                  length L, redrawn from Proffit and Fields (1).

                   It is the Authors’ view that low forces in orthodontics can
               C




                   minimize archwire to bracket binding and resistance to
                   sliding in fixed appliances. Orthodontic archwires, when
    CI




                   deflected (Fig. 1), give a force of response. The force of
                   response produces binding of the archwires at the edges
                   of the bracket slots. Wires with lower force of response
                   can minimize binding during the orthodontic treatment.
                   This model will be explained in the article.
©




                   Materials and methods and discussion

                   Orthodontic archwires can be seen like beams supported
                   on one or two ends (1).
                   It is of fundamental importance to know the behavior of
                   orthodontic archwires in order to understand binding.         Figure 2. Load-deflection diagram.

                   204                                                                             Annali di Stomatologia 2013; IV (2): 204-211
6-Cantarella_- 19/06/13 10:37 Pagina 205




                   The dynforce archwire


                   is able to absorb in the elastic range and is able to give          ets. These systems generate a force that is perpendic-
                   back during the alignment of teeth.                                 ular to the direction of movement of the archwire
                   Wires with higher proportional limit have higher re-                through the bracket slot.
                   silience. They can be bent at greater angles before                 Classical Friction depends on the law traditionally de-
                   they undergo plastic deformation. Infact the proportion-            scribed in friction: classical friction= μ x Fn where:




                                                                                                                                                li
                   al limit is the point at which plastic (permanent) defor-           μ= coefficient of friction,
                   mation starts to occur (1, 2). It is desirable that ortho-          Fn= force perpendicular to the opposing surfaces slid-




                                                                                           na
                   dontic archwires have high resilience so that they can              ing on each other.
                   give back the energy they absorb during the deflection              The coefficient of friction (μ) is an intrinsic property of
                   phase and efficiently align teeth. Other important para-            the wire-bracket couple and it depends on the surface
                   meters to know are the yield strength, represented by               features of the material.




                                                                                         io
                   the point at which 0,1% of permanent deformation is                 Classical friction has been reported (5, 13) to be:
                   measured, and the ultimate strength at which the wire               ➢ almost zero for self-ligating brackets,
                   breaks (1), as shown in Figure 2.                                   ➢ 10 to 29 grams for steel-ligatures,




                                                                                      az
                   The flexural rigidity of an archwire is defined as “E” mul-         ➢ 106 to 138 grams for elastomeric ligatures.
                   tiplied by ”I” (3). “E” is the Modulus of Elasticity of the wire,   Under a clinical standpoint tighter steel ligatures gener-
                   and it depends on the alloy of the wire (stainless steel,           ate higher levels of classical friction because the steel
                   nichel-titanium, beta-titanium or others).                          ligature produces a force that is perpendicular (Fn in




                                                                                   rn
                   “I” is the second moment of inertia. The second moment              the above formula) to the direction of sliding of the wire
                   of inertia is used in structural engineering and it ex-             through the bracket slot. On the other hand, loose steel
                   presses the resistance to deflection of a beam.                     ligatures can be made if low levels of classical friction
                   For orthodontic archwires with rectangular cross-section            are clinically desirable.




                                                                                te
                   “I” is equal to h3w /12 (where “h” is the height and “w” is         Elastomeric ligatures show higher levels of classical
                   the width of the rectangular cross-section).                        friction than steel ligatures. However, the polymers of
                   For orthodontic archwires with round cross-section “I” is           the elastomeric ligatures undergo degradation and
                   equal to π r4/64 (where “r” is the radium of the cross-sec-         plastic deformation (19) and lose 70% of their force 48
                   tion).
                   Under a practical stand-point we can think the second mo-
                                                                             In        hours after placement in the oral environment (6).
                                                                                       Hence it can be expected that 2 days after placement
                   ment of inertia like the cross-section area of the wires.           in the mouth elastomeric ligatures generate 40-50
                   Wires with larger cross-section area have a higher sec-             grams of force (20).
                   ond moment of inertia and therefore are more rigid.
                                                                                       When the archwire is parallel to the bracket slot only
                                                              ni
                   If we want to have a more flexible wire (less rigid) we
                                                                                       classical friction contributes to resistance to sliding.
                   can choose a wire with a lower modulus of elasticity (for
                                                                                       This situation in which the wire does not contact the
                   example choosing nichel-titanium instead of stainless
                                                                                       edges of the bracket slot is called “passive configura-
                                              o

                   steel) or a wire with a smaller cross-section area.
                                                                                       tion” (4) and it is rarely encountered in clinical settings.
                                                                                       With angulation between the wire and the bracket slot,
                   Following is a discussion on the factors that affect re-
                                          izi


                                                                                       the wire starts to contact the edges of the bracket slot
                   sistance to sliding (RS) in orthodontic fixed appliances.
                                                                                       (“critical contact angle for binding”) and binding phe-
                   For the sake of simplicity the discussion will be divided
                                                                                       nomena start to occur (5), as shown in Figure 3. This is
                   in four points.
                                                                                       called the “active configuration”. In binding the archwire
                           Ed




                                                                                       is elastically deformed, and due to its elastic properties
                                                                                       it tends to return to its original shape, generating bind-
                   Point 1 - the Force of Response of the deflected
                                                                                       ing of the wire at the opposing corners of the bracket
                   wires (1, 3)
                                                                                       slot, as shown in Figure 3 (15, 16). Resistance to slid-
                   The Force of Response of the deflected archwire is                  ing due to binding has been reported to reach levels as
                   equal to 3 x E x I x d ÷ L3 where :                                 high as 826 grams (10).
               C




                   E = Modulus of Elasticity of the wire,                              At greater angulations the archwire can no longer with-
                   I = Second Moment of Inertia of the wire                            stand the forces of the slot walls and it begins to per-
    CI




                   d = linear deflection of the wire (as shown in Fig. 1),             manently deform (notching) (5), as shown in Figure 3.
                   L= length of the beam of wire (as shown in Fig. 1),                 Wires with higher force of response generate higher
                   Higher force of response increases the resistance to                levels of binding.
                   sliding (7-10, 12). This concept will be further explained          We saw in point 1 that the force of response of the de-
                   in point 2.                                                         flected wire is equal to 3 x E x I x d ÷ L3.
                                                                                       This formula can explain most of the factors that affect
©




                                                                                       binding, as summarized in the following discussion.
                   Point 2 - Resistance to sliding is the sum of classi-               a. A small inter-bracket distance increases the resi-
                   cal friction, binding, permanent deformation (4).                        stance to sliding (7). In fact a longer beam of wire
                                                                                            (“L” in the above formula) reduces the force of re-
                   Classical friction is generated by the systems that se-                  sponse of the wire by the third power of the length.
                   cure the archwires into the bracket slots: elastomeric              b. A greater angulation between archwire and bracket
                   ties, steel ligatures, clips or slides of self-ligating brack-           slot increases the resistance to sliding (8, 10). In

                   Annali di Stomatologia 2013; IV (2): 204-211                                                                                205
6-Cantarella_- 19/06/13 10:37 Pagina 206




                   D. Cantarella et al.




                                                                                                                                               li
                                                                                      na
                                                                                    io
                                                                                 az
                                                                              rn
                   Figure 3. Resistance to sliding in orthodontic fixed appliances is the sum of Classical Friction, Binding, Permanent Deforma-
                   tion (notching).

                        fact greater deflection (“d” in the above formula) in-      nichel-titanium wire is 60 grams (12x5). In other words,




                                                                           te
                        creases the force of response of the wire.                  at 5 degrees of wire-bracket angulation the resistance
                   c. Stainless Steel wires have coefficients of binding            to sliding of the .019x.025 stainless steel wire (more
                        much higher than nichel-titanium or beta-titanium           rigid, hence with higher force of response) is 270 grams
                        wires (7, 9, 12). In fact greater Modulus of Elasticity     higher than the resistance to sliding of the .016x.022

                        sponse of the deflected wire.
                                                                        In
                        (“E” in the above formula) increases the force of re-       nichel-titanium wire.
                                                                                    Some strategies can be adopted in order to minimize
                   d. A larger cross-section area of the archwire increa-           the force of response of the deflected wires and binding
                        ses the resistance to sliding (8, 10). In fact greater      in clinical orthodontics:
                        second moment of inertia (“I” in the above formula)         a. Use of larger inter-bracket distances, for example
                                                          ni
                        increases the force of response of the deflected wi-             using single wing brackets (14),
                        re. Particularly, Moore et al. (8) found that a             b. Reduction of the angulation between archwire and
                        .021x.025 stainless steel wire has a coefficient of              bracket slots during space closure in sliding mecha-
                        binding three times larger than the coefficient of               nics, for example by means of power arms or by
                                              o

                        binding of a .019x.025 stainless steel wire.                     completely leveling the curve of spee before the
                   Smaller inter-bracket distances, greater angulations                  phase of space closure,
                                          izi


                   between wire and slot, higher modulus of elasticity and          c. Use of archwires with lower modulus of elasticity,
                   larger cross-section areas of wire increase the force of         d. Use of archwires with smaller cross-section area.
                   response of the deflected wire and increase binding of           All above mentioned methods reduce the force of re-
                   the wire against the bracket slot, slowing down tooth            sponse of the deflected wires and reduce resistance to
                          Ed




                   movement.                                                        sliding in orthodontic treatments.
                   It is important also to review the meaning of the Coeffi-        Finally, resistance to sliding is also affected by notch-
                   cient of Binding.                                                ing. Notching (plastic or permanent deformation) hap-
                   Resistance to sliding due to binding is equal to Coeffi-         pens when the wire is deflected beyond the elastic
                   cient of Binding multiplied by wire-bracket angulation           (proportional) limit (1), as shown in Figure 2 and Figure
                   beyond critical contact angle (4).                               3. When the wire is permanently deformed, it does not
               C




                   Studies (7, 8, 10, 11, 13) have been done where the              return to its original shape. Notching causes all motion
                   wire slides through the bracket slot when the bracket            of the archwire through the bracket to cease (5). Clini-
    CI




                   has different angulations in relation to the archwire. A         cally this is particularly important in extraction space
                   diagram is produced where the horizontal axis repre-             closure. The long span of wire running along the ex-
                   sents the wire-bracket relative angulation and the verti-        traction area can be distorted by the food during masti-
                   cal axis represents the resistance to sliding. The slope         cation. Wires with permanent deformation stop any slid-
                   of the curve represents the coefficient of binding.              ing of the wire through the brackets of posterior teeth if
                   The coefficient of binding for the .019x.025 stainless           space closure is performed with sliding mechanics.
©




                   steel wire has been reported to be 66 grams/degree of            A method to increase the proportional limit of stainless
                   wire-bracket angulation (13) and coefficient of binding          steel archwires is heat treatment (2). Wires are heated
                   for the .016x.022 nichel-titanium wire 12 grams/degree           at low temperatures (370 to 480° C) for few minutes af-
                   of wire-bracket angulation (13). For example at 5 de-            ter archwires have been given the archform. Heat treat-
                   grees of wire-bracket angulation resistance to sliding           ment relieves the internal stress generated during the
                   for the .019x.025 stainless steel wire is 330 grams              shaping of the archform (cold working). After heat treat-
                   (66x5), while the resistance to sliding of the .016x.022         ment wires exhibit a higher resilience, in other words

                   206                                                                                Annali di Stomatologia 2013; IV (2): 204-211
6-Cantarella_- 19/06/13 10:37 Pagina 207




                   The dynforce archwire


                   they can be bent at greater angles before they undergo
                   plastic deformation. The measured increase in elastic
                   strength may be as great as 50% (2). Heat treated
                   wires also show a slightly higher (by 10%) modulus of
                   elasticity (2). The advantage of these wires is that they




                                                                                                                                         li
                   maintain their shape during clinical use, improving slid-
                   ing mechanics.




                                                                                    na
                   Point 3 - Archwires with low coefficient of binding
                   are of critical importance to minimize resistance to




                                                                                  io
                   sliding when ceramic brackets are used.

                   Bagby and Ngan (9) studied the coefficient of binding




                                                                               az
                   for the .019x.025 stainless steel wire and for the
                   .019x.025 nichel-titanium wire inserted in different ce-
                   ramic brackets.
                   They found that at 5,9° of wire bracket angulation the




                                                                            rn
                   .019x.025 stainless steel wire has 180-400 grams of re-
                   sistance to sliding, while the .019x.025 nichel-titanium
                   wire has 5-20 grams of resistance to sliding.
                                                                                Figure 4. Tooth movement in sliding mechanics is a multi-
                   Stainless steel wires have lower coefficient of friction




                                                                         te
                                                                                step tipping-uprighting mechanism.
                   than nichel-titanium wires (2), due to the smoother sur-
                   face of stainless steel. However, nichel-titanium has a
                                                                                of binding. Wires with higher resilience are more effec-
                   lower modulus of elasticity than stainless steel, hence
                                                                                tive in the uprighting phase. Orthodontic archwires
                   when it is deflected it has a lower force of response
                   thus minimizing binding.
                                                                      In        have a dynamic behavior. The work and the resilience
                                                                                of the archwires are of critical importance in this
                   According to the findings of this study, when ceramic
                                                                                process.
                   brackets are used in orthodontic treatments, archwires
                                                                                Heat treatment of stainless steel increases the propor-
                   with low coefficients of binding should be utilized in or-
                                                                                tional (elastic) limit of the wire, improving the uprighting
                   der to minimize resistance to sliding.
                                                             ni
                                                                                phase of tooth movement. Heat treated wires are rec-
                                                                                ommended by the authors during space closure with
                                                                                sliding mechanics.
                   Point 4 - Binding is present in orthodontics in most
                                             o

                   clinical situations.                                         The four points explained above are the basis of a pro-
                                                                                tocol aimed at minimize binding in clinical orthodontics.
                                         izi


                   We will analyze the alignment phase and the space clo-       The protocol is characterized by the use of small diam-
                   sure phase.                                                  eter nichel-titanium wires (size .010 or .012) during the
                   During alignment, most of the time teeth are crowded         orthodontic alignment phase and by the use of the dyn-
                   so that the wire exceeds the critical contact angle and      force archwire (18) during the phase of space closure.
                          Ed




                   binding phenomena are present. Small diameter nichel-        Some clinical examples are presented.
                   titanium archwires, with low force of response and low       During the orthodontic alignment phase the use of
                   coefficient of binding are recommended by the authors        small diameter nichel-titanium archwires has several
                   in this phase.                                               advantages. Thinner wires generate lower force when
                   Space closure is performed after the alignment phase         deflected, so it is easier to ligate teeth that are severely
                   is finished. In sliding mechanics the Class I force need-    crowded. Lower forces also minimize the patient dis-
               C




                   ed to close the spaces is generated by elastic chains or     comfort during the first days of orthodontic treatment.
                   coils attached to the brackets. Since brackets are far       Thinner wires with lower force of response also have
    CI




                   from the center of resistance of the tooth, the tooth tips   lower coefficient of binding (13). This is particularly im-
                   until the wire contacts the edges of the bracket slot and    portant during the alignment of highly positioned ca-
                   binding phenomena start to occur (15, 16). The deflect-      nines (Fig. 5).
                   ed wire then tends to return to the original (non-deflect-   Infact, in the presence of high resistance to sliding, the
                   ed) shape and generates a moment of a couple that            wire cannot slide through the brackets of canine, pre-
                   uprights the root of the tooth (17), as shown in Figure 4.   molars, molars. As a consequence spaces may open
©




                   Tipping and uprighting repeat many times until the           between canine and lateral incisor or between canine
                   tooth reaches the final position desired by the ortho-       and first premolar, like shown in Figure 6. Wire to
                   dontist. Orthodontic tooth movement in sliding mechan-       bracket binding would create spacing during the align-
                   ics is not a continuous process; rather it is a multi-step   ment phase and buccal flaring of incisors.
                   “tipping and uprighting” or “binding and releasing”          The use of thin nichel-titanium wires with low force of
                   mechanism. Wires with higher flexibility are more effi-      response and low coefficient of binding allows the wire
                   cient in the tipping phase due to their lower coefficient    to slide through the brackets of canine, premolars and

                   Annali di Stomatologia 2013; IV (2): 204-211                                                                         207
6-Cantarella_- 19/06/13 10:37 Pagina 208




                   D. Cantarella et al.


                                                                                                          Figure 5. Start of alignment of a
                                                                                                          highly positioned canine.




                                                                                                                                          li
                                                                                    na
                                                                                  io
                                                                               az
                                                                            rn
                                                                         te
                                                                                                                   Figure 6. In the pres-
                                                                                                                   ence of high resistance
                                                                      In                                           to sliding, opening of
                                                                                                                   spaces and buccal flar-
                                                                                                                   ing of incisors may oc-
                                                                                                                   cur during the align-
                                                                                                                   ment phase.
                                              o          ni
                                          izi
                          Ed




                   molars, without opening of spaces and without buccal         016x022 nichel-titanium and 019x025 beta-titanium
               C




                   flaring of incisors as shown in Figure 7. It is typical to   wires to finish the leveling/alignment phase.
                   observe the wire coming out distally to the bracket of       During space closure the dynforce archwire (18) is
                   the molar during the alignment phase (Fig 7).                used. The dynforce (Fig. 12) is made of heat-treated
    CI




                   In Figures 8 and 9 we can see the bonding of a patient       stainless steel and has an anterior segment with size
                   with highly positioned canine. A .012 nichel-titanium        .021x.025 occupying the incisor brackets, and posterior
                   wire is inserted the day of the bonding.                     segments with size .018x.025 occupying the brackets
                   Figures 10 and 11 show the patient after 40 days. The        of canines, premolars, molars.
                   canine has been aligned without opening of spaces and        The dynforce low friction (L. F.) has anterior segment
©




                   without buccal flaring of incisors.                          with size .021x.025 and posterior segments with size
                   The .012 nichel-titanium wire has a low force of re-         .018x.022. The material is heat-treated stainless steel
                   sponse and low coefficient of binding, allowing the          in order to reduce indentations (notching) during the
                   wire to slide through the ceramic brackets with mini-        clinical use and improve sliding mechanics. Posterior
                   mum friction and to come out distally to the bracket of      segments (either .018x.025 or .018x.022 in size) are
                   the molar.                                                   more flexible and hence have lower coefficient of bind-
                   After the .012 Ni-Ti, the authors recommend the use of       ing than the conventional .019x.025 stainless steel

                   208                                                                           Annali di Stomatologia 2013; IV (2): 204-211
6-Cantarella_- 19/06/13 10:37 Pagina 209




                   The dynforce archwire


                                                                                                                     Figure 7. In the presence of
                                                                                                                     low resistance to sliding,
                                                                                                                     alignment is performed with-
                                                                                                                     out opening of spaces and
                                                                                                                     without buccal flaring of in-




                                                                                                                                                  li
                                                                                                                     cisors. The archwire comes
                                                                                                                     out distally to the molar




                                                                                        na
                                                                                                                     bracket.




                                                                                      io
                                                                                   az
                                                                                rn
                                                                             te
                                                                          In
                                             o               ni

                   Figures 8 and 9. Frontal and lateral view of start of alignment of a patient with highly positioned canine. Use of .012 nichel-ti-
                   tanium archwire.
                                         izi
                          Ed
               C
    CI




                   Figures 10 and 11. Frontal and lateral view of the patient after 40 days. Alignment of teeth occurred without opening of
                   spaces and without buccal flaring of incisors. Low forces generate low binding. Also, low forces are more easily contrasted
                   by the pressure of the lips (lip bumper effect).
©




                   archwires traditionally used for the retraction of anterior        The anterior segment (size .021x.025) has higher rigidi-
                   teeth. The aim is to minimize binding and notching dur-            ty, in order to maximize the control of incisor tip and
                   ing the phase of space closure. Further, posterior seg-            torque. Higher rigidity also helps to prevent canting of
                   ments (either .018x.025 or .018x.022) have rectangular             the incisal plane when asymmetrical forces are used,
                   cross-section and not round cross-section, because the             for example during midline shift correction.
                   rectangular shape offers a better control of the arch-             Hooks 6,5 mm long are used when the Dynforce arch-
                   form during space closure mechanics.                               wire is utilized with TAD miniscrews.

                   Annali di Stomatologia 2013; IV (2): 204-211                                                                                  209
6-Cantarella_- 19/06/13 10:37 Pagina 210




                   D. Cantarella et al.


                                                                                                                          Figure 12. Dynfor-
                                                                                                                          ce Archwire




                                                                                                                                             li
                                                                                    na
                                                                                  io
                                                                               az
                                                                            rn
                                                                         te
                                                                      In
                                              o          ni
                                          izi



                   Figure 13. Dynforce Archwire with miniscrews placed 7-8 mm above the archwire.
                          Ed




                   As shown in Figure 13 the dynforce can be used in as-
                   sociation with miniscrews positioned between second
                   premolar and first molar 7-8 mm above the archwire.
                   The retracting force is generated by elastic chain run-
                   ning from the miniscrews to the hooks of the archwire.
               C




                   The retracting force passes close to the center of resis-
                   tance of the dental arch in order to produce a bodily
    CI




                   movement of front teeth.
                   In this configuration binding is minimized for two rea-
                   sons:
                   a) Posterior segments of the Dynforce are undersized,
                       hence with lower coefficient of binding,
                   b) Hooks 6,5 mm long work like power arms: the point
©




                       of application of the retracting force is close to the
                       center of resistance of the dental arch, hence the       Figure 14. Start of en-masse retraction performed with the
                                                                                Dynforce archwire and miniscrews.
                       angulation of the wire relative to the brackets and
                       the deflection of the wire are minimized during the
                       retraction phase.                                        archwire low friction (L.F.), with anterior segment with size
                   A clinical case is presented. Figure 14 shows the start of   .021x.025 and posterior segments with size .018x.022.
                   en-masse retraction of anterior teeth with the dynforce      After three months of retraction (Fig. 15) incisors and

                   210                                                                              Annali di Stomatologia 2013; IV (2): 204-211
6-Cantarella_- 19/06/13 10:37 Pagina 211




                   The dynforce archwire


                                                                                retracting forces. Also, ceramic brackets can be rou-
                                                                                tinely used without compromising treatment time.


                                                                                References




                                                                                                                                                    li
                                                                                 1. Proffit WR, Fields HW. Contemporary Orthodontics, Second




                                                                                    na
                                                                                    ed. Mosby 1993; pag.289-302.
                                                                                 2. Philips RW. Skinner’s Science of Dental Materials 1991; W.B.
                                                                                    Saunders Company pag. 18-19; pag. 537-551.
                                                                                 3. Kalpakijan S, Schmid SR. Tecnologia meccanica. Ed Pearson
                                                                                    2008.




                                                                                  io
                                                                                 4. Kusy RP. Ongoing Innovations in biomechanics and materials
                                                                                    for the new millennium. Angle Orthodontist 2000; Vol 70, No 5.
                   Figure 15. After Canine Class I is achieved, retraction is    5. Thorstenson GA, Kusy RP. Effect of archwire size and materi-
                   continued with the Dynforce archwire with reciprocal an-




                                                                               az
                                                                                    al on the resistance to sliding of self-ligating brackets with sec-
                   chorage.                                                         ond-order angulation in the dry state; Am J Orthod Dentofacial
                                                                                    Orthop 2002; 122: 295-305
                                                                                 6. Oshagh M, Ajami S. A comparison of force decay: elastic chain
                                                                                    or tie-back method?. World J Orthod 2010 Winter; 11(4):e45-51.




                                                                            rn
                                                                                 7. Kusy, Whitley. Resistance to sliding of orthodontic appliances
                                                                                    in dry and wet states: influence of archwire alloy, interbracket
                                                                                    distance, and bracket engagement. J Biomed mater Res.
                                                                                    2000 Dec 15; 52(4):797-811.




                                                                         te
                                                                                 8. Moore, Harrington, Rock. Factors affecting friction in the pre-
                                                                                    adjusted appliance. European Journal of Orthodontics 2004;
                                                                                    26(6):579-583.
                                                                                 9. Bagby, Ngan. Frictional Resistance of ceramic brackets when
                                                                      In            subjected to variable tipping moments. The Orthodontic Cy-
                                                                                    berJournal September 2004.
                                                                                10. Frank CA, Nikolai RJ. A comparative study of frictional resis-
                                                                                    tances between orthodontic brackets and arch wires. Am J Or-
                                                                                    thod 1980; 78:593-609.
                                                                                11. Thorstenson GA, Kusy RP. Effects of ligation type and method
                                                             ni
                   Figure 16. Extraction space completely closed.                   on the resistance to sliding of novel orthodontic brackets with
                                                                                    second order angulation in the dry and wet states. Angle Or-
                                                                                    thodontist 2003; 7 (4):418-430.
                                                                                12. Articolo LC, Kusy RP. Influence of angulation on the resistance
                                             o

                   canines moved backwards. Canine class I relationship
                                                                                    to sliding in fixed appliances. Am J Orthod Dentofacial Orthop
                   is achieved and miniscrews are removed. The hooks of             1999 Jan; 115(1):39-51.
                   the dynforce wire are bent with a three prong plier and
                                         izi


                                                                                13. Thorstenson GA, Kusy RP. Comparison of resistance to slid-
                   converted into short hooks. Space closure is then fin-           ing between different self-ligating brackets with second order
                   ished with reciprocal anchorage with elastic chain run-          angulation in the dry and saliva states. Am J Orthod Dentofa-
                   ning from the hook of the archwire to the hook of the            cial Orthop 2002; 121:472-482.
                          Ed




                   molar bracket. Figure 16 shows spaces closed four            14. Wick Alexander RG. The 20 principles of the Alexander Disci-
                   months after the start of retraction. The settling phase         pline. Quintessence Pub 2008.
                   is then performed with conventional methods.                 15. Burrow SJ: Friction and resistance to sliding in orthodontics: A
                                                                                    critical review. American journal of Orthodontics and Dentofa-
                   Efficient sliding mechanics was performed thanks to
                                                                                    cial Orthopedics. 2009, April, Vol 135, Number 4.
                   low wire-bracket binding and proper point of application
                                                                                16. JCO Interviews, Dr. William Proffit on the present and future of
                   of the retracting force.                                         orthodontics. Journal of Clinical Orthodontics, 2008 Dec, Vol-
               C




                                                                                    ume 42, Number 12.
                                                                                17. Nanda R. Biomechanics in Clinical Orthodontics, WB Saun-
                   Conclusions                                                      ders 1997.
    CI




                                                                                18. Cantarella D, Moon HB. Efficient sliding mechanics using Dy-
                   Archwire to bracket binding plays a significant role in          namica Archwire with Anchorplus Mini-Implant Screws
                   sliding mechanics in clinical orthodontics. Binding can          (TADs). American Association of Orthodontics, Boston, may
                   be minimized by appropriate strategies. Particularly, the        1-5 2009, Table Clinics.
                                                                                19. Taloumis LJ, Smith TM, Hondrum SO, Lorton L. Force decay
                   use of low force nichel-titanium archwires (size .010 or
                                                                                    and deformation of orthodontic elastomeric ligatures. Am J Or-
©




                   .012) during the alignment phase, and the use of the             thod Dentofac Orthop 1997; 111:1-11.
                   dynforce archwire during the phase of closure of             20. Melting TR, Odegaard J, Holte K, Segner D. The effect of fric-
                   spaces are advocated by the authors.                             tion on the bending stiffness of orthodontic beams: a theoreti-
                   The advantages of using archwires and mechanics that             cal and in vitro study. Am J Orthod Dentofac Orthop 1999;
                   minimize binding are the possibility to use lower Class I        116:336-345.




                   Annali di Stomatologia 2013; IV (2): 204-211                                                                                   211
