Forum

JL Ackerman The emerging soft tissue

WR Proffit
paradigm in orthodontic
DM Sart•er
diagnosis and treatment
planning

Authors' affiliations: Abstract: Until now, orthodontic diagnosis and treatment

]ames L. Ackerman, Private practice, planning has been based on hard tissue relationships and on
Bryn ~1awr, PA
the Angle paradigm that considers· ideal dental occlusion 'na-
William R. Proffit, Department of Orthodon-
tics, L~ni\·ersity of North Carolina, School of ture's intended ideal form'. In this view, the clinician and na-
Dentistry, Chapel Hill, NC ture are partners in seeking the ideal. In the modem biological
Dal'id M. San·er, Private practice, Vestavia model, variation is accepted as the natural form; ideal occlu-
Hills, AL and Department of Orthodontics,
sion is the exception rather than the rule, and the orthodontist
University of North Carolina, Chapel Hill, NC
and nature are often adversaries. The orthodontist's task is to
Correspondence to: achieve the occlusal and facial t>utcomes that would most .
]ames L. Ackerman, DDS
benefit that individual patient, whose esthetic concerns are of-
931 Haverford Road
Bryn Mawr ten paramount. Because the soft tissues largely determine the
PA 19010-3819 limitations of orthodontic treatment, from the perspectives of
Fax:+ I 610 52i6624 function and stability, as well as esthetics, the orthodontist
USA
must plan treatment within the patient's limits of soft tissue
E-mail: ackermanJL@aol.com
adaptation and soft tissue contours. This emerging soft tissue
paradigm in diagnosis and treatment planning places greater
emphasis on clinical examination of soft tissue function and
esthetics than has previously been the case. and new informa-
tion in these areas is required.

Key words: Angle paradigm; ideal occlusion; relapse; soft

tissue

Dates:
AccerteJ 14 O<tober 1998 A universally accepted scientific perspective, the best cur~
To cite this article: rent explanation of a natural phenomenon, has been
Clin. Onh. Res. Z, 1999: 49- 5Z termed a paradigm (1). Usually, science advances incre~
Ackerman JL, Proffit \X'R, San·er OM:
The emer~ing soft tissue raraJi~o:m in urthoJontk di-
mentally by the cumulative effort of investigators, each
agnosis anJ trt•atmt•nt rlanning adding units of knowledge to the currently accepted
Coryright 10 1\lunksgaarJ 1999 model or paradigm. A paradigm can be thought of as the
ISSN 1397-5927 foundation upon which a scientific structure is erected, as
Ackerman et al. Eml'rging soft tissue raraJigm

if laying brick upon brick of new findings and insights. much of the twentieth century, Darwin and Mendel
Scientific progress proceeds in this appositional fashion, were laying the foundation for our understanding of
until a new way of looking at things arises, and a new adaptation through natural selection and human varia-
paradigm is proposed and accepted. As a new paradigm tion and for a paradigm shift in dentistry and orthodon-
replaces an old one, today's 'truths' become tomorrow's tics based on a broader view of what is best for a
myths. There is generally great resistance on the part patient than just ideal occlusion.
of practitioners of a scientific discipline to acceptance In the Angle paradigm, the orthodontist, through the
of a new paradigm. Nonetheless, once a paradigm shift use of mechanical regulating devices, attempts to allow
has occurred, there is a veritable explosion of new an individual to attain 'nature's intended ideal form'.
ideas and information, leading to rapid advances in the The clinician and nature are partners. In the modern
field. biological model, variation is the theme, and the 'imag-
In orthodontics, at present, we are on the threshold inary ideal' is the exception rather than the rule. The
of a paradigm shift that changes the fundamental con- orthodontist and nature are often adversaries. An at-
ceptual underpinnings of orthodontics, and with it, the tempt to achieve ideal occlusion for all patients is seen
traditional emphasis in diagnosis and treatment plan- as unnatural. The orthodontist's task is to achieve the
ning. Formerly, the emphasis was on the dental and occlusal and facial outcomes that would most benefit
skeletal components; now, greater attention to the soft that individual patient (whose esthetic concerns are of-
tissue aspects of orthodontics is required. For 100 years, ten paramount) (4). This goal must be accomplished
orthodontic theory and practice has been largely based within the bounds of the individual's ability to adapt
on the Angle paradigm (2). This model is predicated on physiologically to the morphological changes that have
a teleological belief system, which holds that nature in- been rendered.
tends for all adults to have perfectly aligned dental In a sense, all orthodontic treatment outcomes are a
arches that should mesh in ideal articulation with the compromise between the orthodontist's wishes and na-
teeth in the opposing jaw. When this 'natural' denti- ture's demands, particularly in the long run. It has
tional state occurs, the face should also be in perfect taken a century, not necessarily to learn, but to accept
harmony and balance and the stomatognathic system that it is the soft tissues that largely determine the lim-
should function ideally. Angle illustrated this idealized itations of orthodontic treatment. Orthodontists have
view with the skull 'Old Glory' and the neoclassical traditionally viewed hard tissue structural discrepancies
Greek sculpture of the head and face of Apollo as the major limitation of treatment. In reality, it is the
Belvedere (3). soft tissues that more closely determine therapeutic
Although Angle's writings were somewhat after those modifiability. The boundaries of dental compensation
of Darwin and Mendel, it is not evident that he was for an underlying jaw discrepancy are established by
influenced by these scientists, whose theories would ul- several aspects of soft tissue relationships and function.
timately revolutionize the study of biology in the early These include 1) pressures exerted on the teeth by the
twentieth century. Angle's concepts were instead based lips, cheeks, and tongue (5); 2) limitations of the peri-
on those of Bonwill, a nineteenth century dentist, who odontal attachment; 3) neuromuscular influences on
practiced and taught in Philadelphia during the time that mandibular position; 4) the contours of the soft tissue
Angle was a student there. Bonwill held that it was facial mask; and 5) lip-tooth relationships and anterior
ordained for the dental arches and articulation of the tooth display during facial animation (6, 7). The physi-
teeth to be in perfect alignment, harmony, and function ologic limits of orthodontic treatment (i.e., the ability of
and that these relationships could be described geomet- the soft tissues to adapt to changes in tooth and jaw
rically. His view was that this ideal plan was present positions) are often narrower than the anatomic limits
from the first creation of life. Bonwill patented the first of treatment. In the correction of a severe malocclusion
dental articulator, a device well suited to the mechanical in a growing patient, it is not unusual to produce a
pursuit of an ideal dental relationship. While Bonwill change of 7-10 mm in molar relationship overjet or
and then Angle were helping to shape dentistry toward overbite. Yet the tolerances for soft tissue adaptation
a largely mechanical orientation that would last for from an equilibrium, periodontal, TMJ, facial balance,

50 I Clm Orth Rel Z. /999;49- 52

 Ackt'rman et al. Emerging soft tissue raraJigm

and anterior tooth display standpoint are often less certain types of therapy for some patients. With this
than half this amount. For instance, in expansion of new concept. as with the old, orthodontic treatment
the lower arch, the envelope is more like 2-3 mm, will continue to provide functional and esthetic
and it is even less for changes in condylar position. benefit to patients. Admittedly, the mission of the
In some ways, we have had it backwards for 100 orthodontist may no longer be divine (i.e., carrying
years. Nature does not intend for the orthodontist to out nature's plan), but instead will merely be human,
achieve perfection, but rather it contends with the so it will be easier to acknowledge that, to a certain
orthodontist trying to achieve perfection. We must extent, we will err. In a sense, the di\·ine role, for-
abandon the traditional Aristotelian 'either/or' view giveness, now is played by the soft tissues. Nor is
that the outcomes of orthodontic treatment are either the new paradigm an excuse for less careful or-
successes or failures based on the standard of ideal thodontics. It does, however, remove some of the
occlusion. Orthodontic results should be evaluated on self-blame and doubt that orthodontists have typically
the basis of overall benefit to the patient and viewed had after their best efforts have resulted in imperfect
as a continuum rather than a single specific end results. The myth of the orthodontic ideal has been
point. Treatment 'failures' are generally the result of perpetuated by presentations at meetings and in the
poor treatment response rather than inadequate treat- literature of patients who overwhelmingly have been
ment, and treatment response is also, to a great ex- the favorable treatment response outliers. Our focus
tent, determined by the soft tissues. Rather than needs to be on the shape of the distribution curve
designating orthodontic treatment outcomes as suc- and the · chance that a particular patient will have a
cesses or failures, patients should be classified as re- favorable or unfavorable response with a particular
sponders and non-responders. Similarly, since treatment procedure.
post-treatment 'relapse' is physiologically determined, This paradigm change is initially unsettling for at
post-retention patients should be characterized as least two reasons: 1) it is revolutionary, in that it
adapters and non-adapters~ Using this construct, the represents a significant philosophical turn in our or-
orthodontic patient population can be represented by thodontic conceptual framework; and 2) documenta-
J •
a bell-shaped curve, with the most favorable respon- tion (records and their measurement) has been and
ders and adapters at one end and the most unfavor- needs to remain the key element in orthodontic diag-
able at the other end. Those patients who, in the nosis and treatment planning. Since we do not yet
past, were presented as the most dramatic successes have as good physiologic probes for evaluating the
and failures were merely the outliers on a normal soft tissues as we have morphometric tools for mea-
distribution curve. Any individual's position on that suring dental and skeletal components, it places
curve will be determined, to a great extent, by soft greater emphasis on the physical examination of the
tissue influences on the treatment process and out- patient than orthodontists have previously been accus-
come. tomed to. If soft tissue function and soft tissue es-
Thus, it is the orthodontist's task in diagnosis and thetics are more important than we previously
treatment planning to ascertain an individual's avail- acknowledged, there is no choice but to become
able limits of soft tissue adaptation, given the dental more aware of both areas. Because a new paradigm
and skeletal changes that the orthodontist and the pa- stimulates the generation of new knowledge of a
tient would like to create. Although, at the present type that was not sought before, we should expect
time, quantitative measurements cannot be rigorously appropriate new information to be developed
applied for soft tissue assessment, the challenge for rapidly.
the future will be to develop methods for doing so. Perhaps it is fitting that for orthodontics, a diag-
This will codify the biologically driven paradigm that nostic paradigm shift accompanies the tum of the
will better serve orthodontics for the twenty-first cen- century. The twenty-first century will certainly see a
tury. new emphasis on soft tissue relationships in or-
The new paradigm in no way diminishes the effi- thodontic diagnosis and treatment planning and a
cacy or value of orthodontic treatment for most pa- greater acknowledgement of biologic variation in de-
tients. It may challenge the long-term effectiveness of termining treatment outcomes.

Cl1n O..h Res l. I99H9-5Z I 51

Ackerman et al. Emerging- soft tis.sue- rtjr<Jdi~m

Abstrakt
Bis heute basierten kieferorthopiidische Diagnose und Behandlungspla- -~~~~~~~M~~~~.~h*~·
nung auf das Verhiiltnis des Hartgewebes und auf dem Angle- ~m•~~~~. ~~~~e·@~~~~~
Paradigma, welches die idcale Okklusion als 'die von der Natur ~ ? "( )E /1) f> tl t::. ~ m ~ m ( nature's
beabsichtigte Ideal form' ansieht. In dieser Hinsicht sind Kliniker unJ
intendedidealform) "c3J.t.I."t7/-!!Jv~
1'\atur Parmer bei der Suche nach dem Ideal. lm modernen biologis-
chen Modell werden Variationen als die nati.irliche Form akzeptiert, 15 ~I: 11·:H~ -c fib :h "'C ~'Ito ~ m'!: ~ * "t
eine ideale Okklusion ist ehcr die Ausnahme als die Regel, und der 0 c ~~? ~ ~. ri:!l!~ ~ c !3 ~ ~ ~ tJd:t /"\- "
Kieferorthopade und die Natur werden oft :u Gegnern. Zicl des T- ~ ~ o o Jj ft ~ 1:.49.1 ~ ~ /] ~ 1:: t:H~ "'C ~;t,
Kieferorthopiiden ist es, die fi.ir den inJividucllen Patienten mit oft-
•~tt~@~~mc~"'C~~~.n;.n. ~~
mals prioritiiren a,thctischc Bedenken optimalen Okklusions- und
Gesichtsergebnisse zu erreichen. Da das Weichgewebe im weiten die ~ ~ ~;t • ?it glj c ~~ ? ~ t) ~ u ~ ~ 9lJ ~ ~ ~ Q 0

Gren:en einer kieferorthopiidischen Behandlung von der Funktion und ~~-c. •~~eEl~~~~~~~~~~~
Stabilitiit sowie auch der Asthetik her festlegt, muB der Kieferortho-
~ M 11: "t o IJ&I ~ c t.;. o o • ~~~ II ~ l:t • W
pade seinen Behandlungsplan innerhalh der Gren:en der Anpass-
ungsfiihigkeit und der Kontur des Weichgewebes erstellen. Das •tt~G~G~fiS~-~~~oMk~~­
daraus entstehende Weichgewebe-Paradigma in Diagnose und ®'/tiiJ~. ~~e:•~~••®~~e~d-t
Behandlungsplan legt einen grii[3eren Schwerpunkt auf die klinische o ~ e:~~oo t::.lt~"'Clt~®:IJ~. ~m•~~•
L'ntersuchung der Funktion und Asthetik des Wcichgewebes als dies
~ M~ ~ I!JU'I- '!: ~ Ji:: "t o ~ c I: t.;. o ~ ~ . fl
bisher der Fall war und beniitigt neue lnformationen in diesen Bere-
ichen. ~~~. ••tte:~~~~~e:~mtt~G.
m•®~&M®~~c-fi~m~~~M•~
~ ~t tl l;f t.;. G t.;. l.- ~ o ~ ~ t.;. G rt 1: M
001 '!: '$!. "'C
•~im'!=t::.-co ?x~. ~~ttfti.aeteii"t
o/J~~. ttm•~~me:••tt~=~~~
~I: .to ~,-~ "'C , ~ :h :J; ~ I: fi :b tl--( ·~ t::. t> ® ct.
Resumen IJ t>:k~~-~tt'!:~'S. ~~~Jf"'t"~ffitt
Hasta hoy, el Jiagnostico ortod(mtico y el plan de tratamiento han ~11Ui'!:~·~c"too
sido basados en relaciones de tejidos duros y en Ia paradigma de
Angle, que considera Ia oclusibn ideal dental 'Ia forma ideal por natu-
raleza.' Desde este punta de vista, el clinico y Ia naturaleza son socios References
al perseguir este mismo ideal. En un modelo biol6gico moderno, I. Kuhn TS. The Strucrure of Scientific Ret·olutiom. Jrd ed. Chicago:
variaciones son aceptadas como Ia forma natural, Ia oclusi{m ideal, es University of Chicago Press; 1996.
Ia excepci6n en vez de Ia regia, y el ortodoncista y Ia naturalcza son 2. Ackerman JL. Orthodontics: art, science or trans-science? Angle
adversarios frecuentes. El trabajo del ortodoncista es el de lograr Ia OrthoJ 1974;44:243-50.
tinalidad facial y oclusal que mas beneticie al paciente, cuyas preocu- 3. Angle EH. Treatment of Malocclusion of the Teeth. 7th ed. Philadel-
paciones esteticas son usualmente lo mas importante. Debido a que el phia: SS White Dental Manufacturing Co.; 1907.
tejido blando determina mayormentc las limitaciones del tratamiento 4. Sarver OM. E.~thetic Orthodontics and Orthognathic Surgcry. St Louis:
ortodontico, desde Ia perspectiva de funci6n y estabilidad a[ igual que CV Mosby Co.; 1997.
en lo estetico, el ortodoncista debe planiticar el tratamiento entre los 5. Proffit WR. Equilibrium theory revisited. Angle Orthod
limites de Ia adaptaci6n y el contorno del tejido blando. Esta 1978;48: 175-86.
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cacibn del diagni>stico y tratamiento, ocupa mayor enfasis en el exa- treatment plannin~: guidelines. Angle Orthod 1997;67:327-36.
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52 I Clm Orrh R··• 2. 1999,49-52