This document provides clinical tips for orthodontists to increase consistency when using a straight-wire appliance. It discusses using "Active Early" case management protocols to control torsion and arch development early in treatment. Diagnosing patients in their natural head position and optimizing micro-esthetics in finishing are emphasized. Bonding brackets to optimize esthetics rather than the center of teeth and using broader arch forms for better esthetics are also recommended.

1. Clinical tips to increase consistency using a
“Straight-Wire Appliance”
Published on November 17, 2015 by Orthodontic Practice
“Everything should be made as simple as possible, but not simpler.” — Einstein
Educational aims and objectives
This article aims to discuss some clinical aspects to increasing consistency using a “Straight-Wire Appliance.”
Expected outcomes
Orthodontic Practice US subscribers can answer the CE questions in our online quiz to earn 2 hours of CE
from reading this article. Correctly answering the questions will demonstrate the reader can:
 Recognize certain clinical benefits to passive self-ligating mechanisms.
 Identify Active Early Case Management Protocols.
 Realize the importance of diagnosing in natural head position.
 Identify some aspects oftorque expression.
 See the value of optimizing microesthetics in finishing.
Orthodontic clinical procedures and esthetic preferences are evolving toward fuller lips, greater enamel
display, and wider smiles with a reduced tendency toward four-premolar extractions, with increased
preference for non-extraction treatment.1 The clinical approaches that we rely on today are different from
those earlier generations of orthodontists used frequently.1 Esthetic declines, once common with treatment,2
are no longer acceptable to the majority of patients,and “straight teeth,” once the predominant treatment goal,
is now secondary to strategies directed toward esthetic improvement3 (Figures 1-2).
Most orthodontists use a variation of the “Straight-Wire Appliance,” a concept that has dominated our
profession since Dr. Larry Andrews’ breakthrough article4 led to its development in the 1970s. In the last 2
decades,appliance developments have revolved around relatively minor changes in appliance prescription,
direct bonding,the development of PSL (Passive Self-Ligating)/ASL (Active Self-Ligating) ligating
mechanisms, increased use of sliding mechanics, and incorporating reduced force levels.5
The recognition that certain torsion concepts of“straight-wire” theory are not congruent with some modern
esthetic goals or with contemporary mechanics does not diminish the value of Dr. Andrews’ landmark
concepts.Orthodontists must appreciate the biomechanical flexibility that is required to use the appliance for
improving the quality of treatment results.
There was a gain in popularity in ASL/PSL systems during the 1990s when small wires in a larger “closed”
slot provided effective movement due to reduced Resistance to Sliding (RTS). For many orthodontists,when
larger rectangular wires were used during major tooth movement, results were disappointing5 with “sloppy
slots” that lacked control of axial inclination and rotations.Passive ligation demands very accurate slots with
special dimensions, particularly in the anterior region for obvious reasons.

2. We favor the use of a PSL mechanism for many reasons:quick wire changes,consistent bracket engagement,
lower forces and wire sliding with control, and improved hygiene, among others.We combine proven PSL
case management strategies6 and “Active Early” approaches7 to control torsion and arch development, with
the improved slot geometry and tighter tolerances of the H4™ appliance (Ortho Classic), along with more
esthetic arch forms.
Clinical Tips
 Don’t get stuck in a biomechanics rut that doesn’t deliver exceptional esthetics: (Impressive
Smile and Facial Esthetics has been my field of interest for the last many years.) Most orthodontists
appreciate Andrews’ “Six Keys to Normal Occlusion” — (Key 1) the characteristics of molar
relationship, (Key 2) crown angulation or tip, (Key 3) crown inclination, (Key 4) no rotations,(Key
5) absence of spaces,and (Key 6) occlusal plane — as being important features of a sound functional
occlusion. The work of Dr. David Sarver clearly describes characteristics of great esthetics that
supplement the criteria applied to normal occlusions8.The biomechanics and case management used
by esthetically motivated orthodontists to achieve great occlusions are likely considerably different
from those who are mainly occlusally motivated. Put simply, “Great Occlusions don’t always equal
great esthetics,” so clinically, find ways to achieve both.
 Try “Active Early” case management protocols: In “Active Early” protocols,7 the appliance is
activated as early as possible, using the Smile Arc Protection (SAP9) bracket position to adjust
vertical position of the incisors, inverting groups of brackets when necessary to activate torsion in
the appliance, selecting archwire progressions that controlaxial inclination early in treatment, wider
arch forms that develop the posterior segments of the arches sooner, esthetic arch shape,ELSE
(Early Light Short Elastics) to control forces and moments, and appropriate disarticulation to
encourage early “wanted” tooth movements.6 This controls early vertical erupion and intrusion of
teeth. Using these strategies improves patient management efficiency for us (Figure 3).
 Diagnose in Natural Head Position (NHP): Diagnosis for esthetics is based on how the patient
presents in day-to-day activity.8 As NHP is reasonably stable in both the short- and long-term,10 the
patient should be assessed comfortably standing,engaged in natural conversation,and generating
unposed smiles. The orthodontist then makes patient specific determinations of bracket height
progressions to generate optimal enamel display8 and assesses the requirement for creation of torsion
within the appliance to optimize axial inclination of the maxillary anterior teeth (Figure 4). Far too
many finished orthodontic patients end up with proclined maxillary incisors,so we are purposeful in
the assessment.

3.  Optimize
tooth shape, and improve gingival contour prior to bonding: The value of optimizing micro-
esthetics in finishing is well appreciated.11 The less common strategy of creating a normalized
contourof the teeth through positive and negative coronoplasty prior to bonding creates a number of
opportunities.Ability to place brackets in vertical positions designed to enhance the smile arc,
simplified correction of rotational control, and more predictable performance in third order
movements are all benefits of normalizing tooth shape and contourprior to bonding.As SAP upper
bracket positions to optimize esthetics are frequently more gingival than conventional positions,soft
tissue recontouring can be a tremendous advantage when needed (Figure 5).
 Increase torsion “built into” the appliance by “flipping” where needed: Torque expression is a
complex process dependent upon12 magnitude of torsion,wire stiffness or resilience, bracket design,
engagement angle, mode of ligation, wire dimension and corner radius of the wire, angulation of the
bracket, deformation of the bracket or wire undertorsion, manufacturing tolerances in the bracket
and the wire, initial tooth inclination, bracket position, and the measurement technique used to
evaluate torsion.Fortunately, to the clinician, it matters solely when/if torsion is developed within
the slot during commonly used archwire progressions.

5. With the worldwide tendency to treat more patients without extractions, the control of proclination of the
maxillary anterior teeth has become a greater challenge. The correction of pre-existing crowding and
proclination, proclination associated with relief of crowding during traditional round wire mechanics, or
incisor proclination-associated Class III elastics is particularly problematic. The challenge for many non-
extraction patients has been in getting enough lingual crown torsion without having to resort to complex wire
bending to attain esthetic results. These are patients that benefit from “flipping (upper anteriors) and flocking
(upper cupid)” the maxillary anterior/canine brackets.13
The “tooth by tooth” method of varying torsion “built into” the appliance is not as efficient for us and
frequently requires either repositioning of brackets, or complex wire bending to finish precisely.14 In contrast,
“flipping and flocking” and varying torsion in groups is far more predictable, requires fewer bracket
repositions,and allows wire adjustments with uniformly “spun” wires (Figures 6-7).
 Bond brackets to optimize esthetics not at the center of anatomic crown (FA): As today’s
treatment targets for incisor position in three planes of space are based on esthetics,8,15 the reliance
on “treatment built” into an appliance for the anterior teeth relative to the occlusal plane is not a
practical way to ensure esthetically superior results.In the “Active Early” approach, individualized
bracket positions based on esthetics7 (SAP)is combined with other initial planning considerations to
gain control of maxillary incisor vertical position. For patients with “flat” occlusal planes or those
that require increased enamel display, the divergence of the upperwire plane from molar to incisor
created by bracket position must increase to develop the smile arc by extruding the upper incisors
relative to the upperpremolars. In patients with normal occlusal planes, a more modest progression
in the upper wire plane is still advisable to protect the smile arc as we broaden the maxillary arch
with treatment. A modest progression in still advised in deep bite cases to avoid excessive reduction
in the smile arc as the overbite reduces. Compensating changes in the mandibular wire plane levels
the mandibular arch and establishes an optimum overbite. It is not necessary to have a deeper bite to
have a great smile arc.
Andrews’ “Six Keys” article, acknowledged as the catalyst for development of the first fully pre-adjusted
appliance, advocates using the centerof the clinical crown (FA), the long axis of the center of the clinical

6. crown, and the thickness of the clinical crown from the long axis to FA,5 as guides for bracket positioning.
This limits the usefulness of the appliance for patients whose teeth or faces deviate from “normal standards.”
We do not subscribe to the core “straight-wire” principle that the wire plane must parallel the occlusal plane
to attain excellent occlusions,and failure to adjust bracket height to adjust vertical positions of the maxillary
incisors can result in esthetic deterioration. SAP bracket placement strategy allows adjustment of the vertical
position of the maxillary incisors, which improves their display and the smile arc without increasing the
overbite (Figure 8).
 Appreciate the reality of undersize wires and oversized slots: Contemporary fixed orthodontic
treatment is usually completed in wire sizes that are less than full dimension15 for the designed
bracket slot dimensions. This seems gentler on the patient, and the consequences ofthis incompletely
filled bracket lumen is torsional play that decreases engagement of the contact between the archwire
and the bracket.16 While decreasing friction — a potential benefit during early leveling, aligning, and
sliding mechanics — torsional play reduces control of axial inclination necessary for ideal esthetics.
In clinical practice, incremental increases in archwire size is NOT the most effective means of
controlling axial inclination when the slot isn’t filled7 (Figure 9).
 Understand the appliance system you are using: Manufacturing tolerances also vary greatly so
that the ability of the appliance to generate torsion with a specific wire progression and deliver stated
appliance Rx17 is really what matters. Fortunately, to the clinician, it matters solely when/if torsion
develops within the slot during commonly used archwire progressions.Unfortunately,many
manufacturer’s tolerances often cause variable slot sizes, which makes torsion unpredictable.
However, with the H4 bracket, the manufacturing tolerances are predictably accurate, with reduced
slot depth leading to less wire adjustments. By varying bracket height with SAP bracket positioning
and “flipping and flocking” maxillary anterior brackets when needed,lingual crown torsion is
assured.By proper management of mandibular incisors, those teeth can be kept upright when
required (Figure 10).
 Use broader arch forms for better esthetics: Dr. Pitts has found that broader arch width, (not in
the canine region) especially in the molars is more attractive, and smaller buccal corridors are
preferred in both men and women. The alignment and broadening of maxillary and mandibular
dental arches to reduce buccal corridors and producing “10” or “12” tooth smiles results in more
space for the anteriors to have more lingual crown torque/inclination. Of course, proper inclination
of the premolars and molars must be maintained upon broadening.Research has confirmed that final
arch width is a function of arch form, not of the bracket18 used during treatment, so an improved arch
form is required for improved esthetics.
One of the biggest impacts on transverse arch dimension in the molars, and arch form in general has been the
adoption of “Pitts’ Broad” arch forms in both nonadjustable and adjustable wire profiles (Ortho Classic). This
arch form improves the “flow” of mini-esthetics, making the attainment of a “12 tooth” smile much easier. By
using a moderate progression SAP bracket placement, the orthodontist can broaden the arches and still
maintain a beautiful smile arc (Figures 11-15). In short, the shape of the arch is just as important as the width.
 Finish micro-esthetics details with optimal esthetics in mind: It was primarily the efforts of Dr.
David Sarver who classified the concepts ofmacro-, mini-, and micro-esthetics19. While optimizing
the “white and pink” tissues has been common practice in esthetic dentistry,it is less common in
orthodontics20.By mastering the techniques and disciplines applied in cosmetic dentistry,patients
have the potential to finish with wonderful micro-esthetics that provide the final touch to patients
who have well managed macro- and mini-esthetic results (Figure 16). We take particular care in
avoiding “black triangles” at the gingival papilla through management of contacts and connectors
during the finishing process.

8. It is an exciting time to be in orthodontics.Contemporary esthetic-based diagnosis,a modern understanding of
how to optimize straight-wire appliances,use of advanced straight-wire appliances that control axial
inclination and rotations,using esthetic broader arch forms, adopting the “Active Early” approach to case
management, and finishing “white and pink” tissues foresthetics provide expanded opportunities for
improving esthetics.In the “Active Early” approach,lighter forces, applied earlier, for longer duration are
accomplishing many things more efficiently for the orthodontist and more gentleness forthe patient than has
ever been possible before.
Author Info
Tom Pitts, DDS, MSD, is a world-renowned lecturer and clinician, highly recognized for his continued
teaching of orthodontic finishing and clinical excellence. Dr. Pitts is an associate clinical professorat the
University of the Pacific and founder of the well-respected Pitts Progressive Study Club. Dr. Pitts has been
published in multiple journals and clinical publications. He has been actively teaching the orthodontic
community in a variety of settings both nationally and internationally since 1986.

9. Duncan Brown, DDS, MS, is a highly regarded international speaker and educator in passive ligation bracket
systems.Dr. Brown teaches regularly at the University of Alberta and University of Manitoba and is also a
Kodak/Carestream Dental speaker and consultant.
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