Orthodontic Treatment Planning

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DIAGNOSIS AND TREATMENT PLANNING
EXCELLENCE IN ORTHODONTICS 2012

Chapter

3

Diagnosis and treatment planning
Nigel Harradine

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DIAGNOSIS AND TREATMENT PLANNING
EXCELLENCE IN ORTHODONTICS 2012

Introduction
The chapter on Occlusal Treatment Goals considers what our occlusal goals should be. This chapter addresses
further important questions of diagnosis and treatment planning:






where would we ideally like to place this occlusion horizontally and vertically within the face?
exactly what aspects of the appearance and function of the teeth and face are a source of
dissatisfaction to the patient?
what are the diagnostic features, which we need to observe to decide how we can find the best
means of satisfying these requirements?
how do extractions affect aesthetics, stability and ease of treatment?

With regard to the first point, the vertical position of the occlusion is also important to remember and we should
ensure that our treatment mechanics avoid unwanted extrusion of the molars or incisors. The scope for altering
the vertical position of the occlusion orthodontically is covered in other chapters. This chapter will discuss the
anteroposterior position of the occlusion and the width of the occlusion. Decisions need to be reached as to what
is desirable and what is achievable.
In relation to the second point, a gummy smile is a good example of a dentofacial feature which may or may not
bother the patient.
A list of diagnostic features relating to these aspects is clearly required and also decisions about how best to
assess them.
The last part of this chapter focuses on extraction decisions, which are such an important part of the planning
process.
It is inappropriate in this manual to deal in detail with all the potentially relevant features, such as measuring the
overjet or assessing the molar relationship. Nor is a level of detail appropriate for orthognathic cases included
here. Rather, this section is a core checklist to avoid important categories of data being neglected and to suggest
appropriate measures in some categories.

The occlusion

Important aspects of occlusal planning have been covered in the chapter on Occlusal Treatment Goals. However,
other factors, notably dental disease or missing or previously extracted teeth will alter the potential choice of
occlusal goals.

Features important in diagnosis
The facial soft-tissue profile
The two most important features are probably the prominence of the lips relative to the nose and chin (assessed
via the lower lip to E line distance or using Merrifield’s line) and the nasolabial angle (NLA). These have their
limitations but are also quick and easy to apply and therefore stand a good chance of being incorporated in
routine orthodontic diagnosis. One of the limitations of the NLA (Figure 3.1) is that it comprises both the angle of
the lower surface of the nose and also the inclination of the upper lip and facial aesthetics in profile may be more
influenced by the latter. An angle between a tangent to the upper lip and the facial horizontal (Figure 3.2) might
be a better measure of the aesthetics of upper lip profile but is not in common use and the NLA with intelligent
interpretation may therefore be preferred.
The Holdaway angle is another well-known measure of balance in facial profile. It has been used in the British
Orthodontic Society national audit of successively treated orthognathic cases (Johnston et al 2006), and is now
officially recommended by the BOS clinical effectiveness committee as one of seven cephalometric measures to

DIAGNOSIS AND TREATMENT PLANNING
EXCELLENCE IN ORTHODONTICS 2012

Figure 3.1:
The nasolabial angle (NLA). This is a well established aesthetic indicator, but may not be the best guide to
aesthetics of the upper lip profile

Figure 3.2:

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A suggested alternative to NLA. The lip inclination

audit the outcome of orthognathic cases. OPAL, which is produced on behalf of the British Orthodontic Society,
was used to measure and extract the data and the Holdaway angle is
now included in the OPAL analysis. This angle is open to a little confusion both from differences in definition and
also depending on whether the correction factor for the skeletal convexity is applied. The original papers
(Holdaway 1983, Holdaway 1984) are recommended and fully explain his thoughts with plenty of examples. The
norm is entirely his opinion. A paper by Basciftci et al (2003) used this angle and is a good example of the angle in
action as a measure of balance in facial profile. The angle in its conventional definition is between soft tissue
nasion-soft pogonion and soft pogonion-labrale superius. The larger the facial convexity (i.e. the more skeletal
class 2), the larger the angle should be, according to Holdaway. Interestingly, both the Turkish dental students in
this paper and the Bolton norms have Holdaway angles at the very upper end of ‘normal’ according to Holdaway.
OPAL gives both the uncorrected value and the value corrected for convexity according to Holdaway’s formula.
An important point about Merrifield’s line and the Holdaway angle are that they do not include nose prominence
in the assessment of facial balance whereas the Rickets E line does.
A relatively straightforward and interesting analysis for assessing soft tissue balance has been proposed by Bass
(2003). The anteroposterior positions of the lips and chin are
assessed in relation to a perpendicular from subnasale. This
analysis is linear as is Ricketts E line assessment but like the
Holdaway analysis, disregards the nose. An appealing aspect in
principle is the use of a natural vertical obtained from posing
during a lateral photograph, which is then transferred to the
cephalometric x-ray. This uses a simple protractor and the E line as
a reference common to photograph and cephalogram. A simple
method of recording natural head posture is intuitively a sensible
way to view aesthetics of the soft tissues. Some digitising
programs such as OPAL, permit the recording of natural vertical
and then make antero-posterior measurements - e.g. of the nose
and chin - in relation to it. This method may increase the
popularity of using a natural head posture.
Figure 3.3:
The Holdaway angle. A measure
of facial balance which excludes the nose

The lips

The vertical resting and smiling (upper lip) lip lines are important in

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relation to appearance and in some cases to the stability of overjet reduction. These can be measured in mm
relative to the upper incisor tip. If any upper gum is shown during smiling, this may be a cause of concern to the
patient and this possibility should be explored. Interestingly, Johnson and Smith (1995) propose, in a study on
smile width, that the most important feature of a smile that both affects aesthetics and is also affected by
orthodontics, is the amount of maxillary gingivae displayed. Their examples of smiles judged to have a poor
appearance by a lay panel seem to support this view.

The A-P and vertical skeletal pattern and the incisor inclinations
A well-known variety of cephalometric parameters exist for these assessments.

Temporomandibular joint dysfunction

Although clinically significant signs and symptoms seem uncommon and there is good evidence that orthodontic
treatment does not cause this potential problem, it is quick and easy to at least be aware of the existence and
extent of any signs and symptoms.





joint noises?
discomfort with jaw movement / muscle tenderness?
amount of opening and lateral excursion in mm. This can be recorded in the notes in simple
diagrammatic form and is a good objective sign of a change in actual joint dysfunction. Opening is
usually > 40 mm and lateral excursion > an upper incisor width.

The patient's actual complaints
For example: Is the patient bothered by the prominent upper teeth or also by the receding chin? This may
profoundly affect the chosen plan in cases of borderline skeletal severity. Is the patient bothered by the
appearance or function of an anterior open bite or is it the long face or the gummy smile that are the main
concern? This may strongly influence the choice between Young Kim type orthodontic mechanics and a Le Fort
osteotomy.

Patient compliance
The literature has to date been largely unhelpful in identifying predictors of lack of patient compliance. Midtreatment indicators such as a failure to attend or to progress in the early stages of treatment are of some help,
but we still have almost no scientific ability to pick winners in advance. The study by O’Brien et al (2003) did show
that a geographical measure of likely social deprivation (the postcode) did significantly predict levels of
compliance with functional appliances. However, it is debatable as to how much we would alter the treatment
plan in the light of the patient’s address.

Age and sex

Spontaneous space closure has been clearly shown by Stephens and Houston (1985) to be highly related to the
rate and amount of remaining growth. Johnston has shown (e.g. Livieratos and Johnston 1995) in studies using
his pitchfork analysis (Johnston 1996) that in a growing patient, a significant part of the correction of a class 2
molar relationship in a non-extraction case is, on average, due to temporary inhibition of maxillary growth and
continuing mandibular growth. This is clearly a large factor to consider when choosing mechanics in a patient
with little or no remaining growth.

The problem list
Having gathered all the relevant data, we would strongly advocate the compilation of a problem list before
deciding on treatment aims and subsequently, treatment means. The advantages of a problem list can be
summarised as follows:




it turns a mass of data into a short and relevant list
no problems are forgotten – at the treatment planning stage or later

DIAGNOSIS AND TREATMENT PLANNING
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it focuses thought on the actual problems
it enables problems to be recorded as fully noted, even if the subsequent list of treatment aims
includes a decision to accept a problem rather than to attempt to resolve it.

These are powerful advantages in making good plans, in keeping track of treatment aims during treatment and in
recording the limitations of treatment aims. A list of treatment aims will of necessity address all the problems in
the list and will lead to a rational selection of the best means of treatment for that patient
The sequence of forming a plan should therefore be:





compile a problem list
list the treatment aims
list the treatment means

General and specific treatment aims

Any specific list of treatment aims will be compiled against an underlying set of general treatment aims or
principles. For example, we need to have answers to all the following questions:







what final occlusion do I normally aim for?
what general aims do I have about changes in arch width and shape?
what do I believe is desirable/achievable regarding vertical tooth position?
what general aims do I have for antero-posterior lower incisor position?
what are my general views about the effects of extractions and what factors influence my choice of
extractions?

All these questions are addressed in one of the chapters of this manual, with the last two being a particular focus
of this chapter. It will not surprise readers to hear that we feel that every orthodontist needs views on these
questions that are based on the best available evidence, although it needs to be recognised that the current
evidence is far from ideal on many of these points. A paper by Lysle Johnston (1998) is typically iconoclastic on
this subject and very well worth a read. It is entitled “The value of information and the cost of uncertainty: who
foots the bill?”

Antero-posterior incisor position
This is a highly important part of any treatment plan. Given that our occlusal goals usually include a class I incisor
relationship, the question becomes one of where to aim to put the lower incisors. This should be considered first
in its own right and then in relation to extraction philosophy since this a very important determinant of final lower
incisor position. This question is very amenable to cephalometric analysis and many well-known cephalometric
goals for lower incisor position have been advocated. Those by Tweed, Steiner, Merrifield, (1996) Ricketts, Downs,
Mills (1966) and Holdaway are representative (see the book by Athanasiou 1995). The questions that should be
asked about any goal for incisor position are:







does it produce results that are more stable?
are the results more aesthetic?
does it facilitate a good occlusion?
can the planned position be more easily achieved than others?
is the planned incisor position conducive to long-term dental health?

Stability and lower incisor position
The most crucial questions are the first three. Regarding stability, few people now dispute that no treatment goal
is likely to produce more stable results than those obtained when following Mills’ goal (1968) of aiming to leave

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the average incisor labiolingual position unchanged during treatment. The question is whether other guides to
end-of-treatment incisor position will produce results that are equally stable anteroposteriorly. In the past, many
have claimed or implied - contrary to Mills’ findings - that their analysis or goal will consistently produce
substantial and stable labiolingual change in lower incisor position. The evidence to support this is very slim
although individual cases of such a stable change undoubtedly occur. Mills (1966) found that lower incisors which
were proclined or retroclined by a minimum of 7 degrees during treatment relapsed by an average of 50% posttreatment. The extent of these post-treatment changes correlated significantly with the amount of labiolingual
movement, although there were unpredictable individual exceptions. A study by Houston and Edler (1990)
provided strong evidence that the APo line is not a position of lower incisor stability. They also found that in 62%
of cases the incisors tended to return towards their starting A-P position. In the remaining cases, the posttreatment A-P changes were haphazard. More recent studies have produced similar findings. Hansen, Koutsonas
and Pancherz (1997) found that incisors proclined an average of 11 degrees or 3.2 mm retroclined an average of 8
degrees or 2.5 mm in the following six months when no appliances were in place. Stucki and Ingervall (1998)
found that on average 70% of the proclination produced by Jasper Jumpers subsequently relapsed.
Sims and Springate (1995) investigated more modest A-P alterations in lower incisor position and found a similar
tendency for incisors moved labially during treatment to return towards their starting position, but found that
modest retroclination of incisors was stable or even increased post-retention. This is one of several hints in the
literature that invasion of the space previously occupied by the tongue is more stable than invasion of lip or cheek
space. These authors also commented on the wide standard deviation of post-treatment change around the
average changes.
A study by Williams and Andersen (1995) investigated the very interesting idea that lower incisor proclination
might prove to be stable in those patients in whom the mandible is expected to develop in an anterior rotational
pattern according to the morphological features described by Bjork. The treatment would in effect be taking
advantage of the natural tendency for lower incisors to compensate by proclining as the mandible rotates
anteriorly. The authors found an average proclination during treatment of 9 degrees with an average relapse of
3.4 degrees and an average treatment change relative to APo of 2.7 mm with an average relapse of 1.2 mm. The
degree of relapse was very significantly related to the amount of labial movement or proclination although some
cases were a marked exception to the general rule. Disappointingly, anterior rotators are no more likely to permit
stable lower incisor proclination than other groups.
This paper therefore supports the previous studies, but can similarly be interpreted in two ways:



proclination tends to be unstable

or alternatively,



approximately 60% of the proclination remains

Both these statements are true, but many clinicians seem to recall only one of them. Several details of the study
by Anderson and Williams are worth noting. Firstly, all cases were retained until skeletal maturity (hand-wrist
radiographs) - an average of 3.3 years. Secondly, the post-retention Little’s index was much better than most of
those reported by Little (1990) (2.8 mm vs. 4.7 mm). Was this due to the long retention until cessation of growth
or is it related to the anterior growth rotation? Thirdly, the relapse in lower incisor labial movement was not
related to the relapse in Little’s index, which again proved hard to statistically attribute to any parameter other
than expansion during treatment of the intercanine width. Finally we should note that not all of those predicted
to rotate anteriorly, actually did. Also, marked pogonial growth made some cases appear to have no linear
movement of the lower incisors in spite of definite proclination relative to the mandibular plane. An interesting
paper!
Key point:
Stability of A-P incisor change is not statistically related to stability of irregularity. “Stability” can mean different
things.

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Paquette et al (1992) also found that cases which had been treated with an average of 2.8 mm. more lower incisor
proclination than another matched group of cases, finished with slightly greater irregularity (Little’s index) out of
retention. The difference in post-treatment relapse of irregularity between the two groups was very small (0.6
mm), but the findings did suggest that labial movement of lower incisors during treatment does, on average,
increase the chance of subsequent relapse.
No study has demonstrated consistent anteroposterior stability in a group of orthodontic cases in which the lower
incisors have been significantly changed in their A-P position during treatment. Reviewing current knowledge on
the ability of the soft tissues to adapt to lower arch expansion, Ackerman and Proffit (1997) propose an
approximate limit of 2 mm for labial movement of the lower incisors if anteroposterior stability is the main factor
influencing our decision.
It is of interest to detour for a moment and note that Artun et al (1990) found that substantial (>10 degrees)
proclination of lower incisors was not associated with greater subsequent relapse than a group treated without
proclination. However, these were severe Class 3 patients who, subsequent to lower incisor proclination, had a
backward mandibular sagittal split osteotomy; i.e. if the soft tissue environment is radically changed by surgical
repositioning of the jaw, the usual soft tissue effects do not seem to apply.
An interesting suggestion is the one formally advocated by Selwyn-Barnett (1996) who points out that in effect
the lips cannot ‘know’ which incisor is touching them and that we can therefore procline the lower incisor in class
2 division ii cases to touch the lower lip at the same A-P position as was occupied before treatment by the
extruded upper incisor. The stability of the results of such a philosophy has not been well tested, but the resulting
plan is often required in any case to achieve occlusal goals (Andrews’ keys 3 and 6) and is a useful way of
structuring a plan to procline the lower incisors in such cases, as well as a sensible hypothesis about stability.
However, Canut and Arias (1999) found that proclining lower incisors in class 2 division ii cases leads to much
more relapse of arch irregularity than when the arch length was not increased. This is salutary evidence that a
plausible hypothesis may be incorrect. We aim to retain with particular care Class 2 division 2 cases in which we
have substantially proclined the lower incisors and with increasing emphasis on informed consent, prior
information about the need for and importance of retention is especially relevant in these cases.
An impressive long-term study by Jonsson and Magnusson (2010) over 25 years found that treatments involving
extractions produced much less relapse of crowding in both arches when compared with non-extraction cases,
particularly in the lower arch. Cephalometrics was not included in this study but it is probable that non-extraction
cases involved labial movement of the incisors.

Aesthetics and incisor position

Most proponents of a particular anteroposterior goal for the dentition have based their advocacy primarily on the
aesthetic advantages. There is, however, very little direct evidence concerning this question. An opinion may be
formed based on the fact that the Tweed analysis frequently retroclines lower incisors and the Ricketts analysis
frequently plans for labial movement of lower incisors, but what also matters aesthetically in this respect is the
anteroposterior position of the overlying lips and this is extremely variable. Park and Burstone (1986) have shown
in a very elegantly conceived study that the soft tissue appearance of the lips in relation to a soft - tissue APo line
varies enormously even when the Ricketts hard tissue APo line goal is exactly achieved. Achievement of a
particular lower incisor position will therefore produce an enormous variety of profiles, although it is still probably
true that for any given patient, some lower incisor positions will produce a more aesthetic lip position than others.
Even here, opinions vary as to what is an aesthetically desirable goal, treatment to Merrifield’s profile line tending
to produce less prominent lips than treatment to Ricketts’ E line for example.
Variability of soft tissue response
Quite separate from this question of variability in soft tissues for a given hard tissue position is the fact of the
variability of soft tissue response to tooth movement. This is also well documented. Staggers (1990), for example,
comparing premolar and second molar extractions, found definite differences in the A-P changes in incisor
position between the two groups, but no differences in the changes in soft-tissue facial convexity or of the upper
lip relationship to a soft-tissue APo line. Almost all studies show that the soft tissues move much less than the

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underlying teeth. For example, Paquette, Beattie and Johnston (1992) found an average 1.4 mm posterior
movement of the upper lip when the upper incisors were retracted by an average of 5.0 mm – an average ratio of
28%. Large tooth movements are therefore required on average to produce clinically substantial soft tissue
change, but the variability is huge. In this paper, the range of upper lip anteroposterior change associated with
upper incisor retraction was 10.0 mm! Pancherz and Anehus-Pancherz (1993) reported that there was no
correlation (r=0.02) between the hard and the soft tissue changes brought about by treatment with the Herbst
appliance. More recent papers have continued to find poor correlation between incisor movement and change in
the overlying lips. Kusnoto and Kusnoto (2001) found a correlation coefficient of r=0.39 for the upper lip. In other
words, the change in incisor position accounted for r2 = 16% of the variation in lip change. The average ratio of
movement was 1:4 for lip: incisor change. A paper by Lai et al (2000) suffers from choices in cephalometric values,
which greatly lessen the potential usefulness of the results, but still reveals “a large variation in the soft tissue
response to dental movements”. The paper includes the result that two groups which differed in their change in
upper incisor inclination during treatment by an average of 20 degrees, differed in their change in upper lip to E
line distance by an average of only 0.5 mm. This large variation in soft tissue response was emphasised again in a
more recent study by Tadic et al (2007) which focused on predictors of change in lip shape and NLA with upper
incisor correction in class II cases. They found a large range of change in NLA (40 degrees) and no correlation with
incisor A-P change.
Key Point:
Changes in anteroposterior incisor position clearly result in much smaller and highly variable changes in the
prominence and shape of the overlying lips. Prediction of changes in lip profile is prone to substantial error.
What degree of lip prominence is considered attractive?
A final factor when weighing the aesthetic consequences of incisor prominence is the variety of opinion as to what
is an attractive degree of lip prominence. This has been investigated in several studies and a good paper which
includes a good summary of the literature is the one by Nomura et al (2009). Lay judges from different racial
groups were asked to rate lips of varying prominence in silhouette profiles of disclosed racial groups. Several
useful findings emerged. For example all judges of all racial groups prefer the lips to be behind Ricketts E line in all
racial groups. Hispanic and Japanese judges prefer more retruded lips and white and Kenyan judges have very
similar views on lip prominence. This paper repays a read and may help set a target for lip prominence which is
more likely to be appropriate for a given patient.

A suggested lower incisor target position

All orthodontists need to look at the available evidence and decide their general aims in relation to this important
target. As a starting point, the evidence relating to stability indicates that we should aim not to change the
antero-posterior position significantly during treatment unless there is a good reason. Most orthodontic cases (as
opposed to orthognathic surgical cases) can be treated without significantly altering the labiolingual position of
the lower incisors. Also, the aesthetic consequences of changing their position are unpredictable and usually
small. However, if this goal of aiming for little change in the initial antero-posterior position is unwaveringly
followed, there are several categories of patient where this would have substantial disadvantages.






in some cases, the aesthetic concerns of lip prominence or inclination are sufficiently marked that
they outweigh considerations of stability. For example, in a well-aligned class 1 bimaxillary
proclination case, excessive lip and tooth prominence is probably the only potential indication for
treatment. Equally, some class 2 cases have a very obtuse nasolabial angle. This can be a strong
factor to tip the treatment plan towards surgery. Where surgery is not an option, this factor may
sometimes lead to a decision to plan for significant lower incisor proclination to maintain upper lip
support whilst reducing the overjet.
some cases (e.g. some class 2 division ii patients) are impossible to treat to our chosen occlusal
goals without substantial lower incisor proclination.
some cases with reduced or negative overbite require extractions to retrocline the incisors and
achieve an overbite

DIAGNOSIS AND TREATMENT PLANNING
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correction of class 3 cases without orthognathic surgery frequently requires significant lower
incisor retroclination.
many cases with mild lower arch crowding are very demanding on the wear of class 2 traction if
lower arch extractions are prescribed and unwanted incisor retroclination is to be avoided. It is
better to move the lower incisors labially to the modest extent required.
from a purely pragmatic viewpoint, some cases become extremely anchorage demanding if the
lower incisors are not moved labially. This point is less frequently mentioned than others such as
considerations of profile, but can undoubtedly be a powerful if unstated motive.

Aesthetics versus stability?
Small anteroposterior changes in lower incisor position are of little consequence for either appearance or stability.
The evidence is that the larger the change, the more these two factors will - on average - conflict. Choosing a
position that is less likely to be stable means more emphasis on ‘permanent’ retention and this is the source of a
philosophical dilemma. The work of Little and others quoted above has shown that although larger lower incisor
changes in position are less stable, lower incisor alignment tends to deteriorate after retention whether or not the
anteroposterior lower incisor position has been maintained. Little personally advocates fixed indefinite retention
for lower incisors after all orthodontic treatment. In the light of this, two tenable viewpoints have emerged.
Since tooth alignment tends to deteriorate even if we put the teeth where stability is most probable:



all cases should have indefinite retention and if this is the case, then why should the orthodontist
be concerned with minimising spontaneous relapse when all case are to be retained forever
anyway?

Or alternatively



for one reason or another few young patients wear retainers for the rest of their life and it is
therefore best practice to try to leave the lower incisors in a position that minimises the probability
of relapse when retention is discontinued.

These two approaches are both entirely tenable. At present we favour the second viewpoint as a starting point,
but with some definite exceptions for the aesthetic, occlusal and anchorage reasons listed above. A complicating
factor for those looking for certainties in life is that all these exceptions are relative and thus open to weighting
which varies even between clinicians who would subscribe to the same choice between the two opposing
viewpoints. The chapter on Stability and Retention discusses further the evidence about stability in general and
the best practical approach to retention in the light of this evidence.
The question of a suitable goal for lower incisor position is inextricably entwined with extraction philosophy and
the merits and disadvantages of extractions per se should now be examined - a subject of recently revived
controversy.

Extractions versus non - extraction treatment
This ancient debate about the possible benefits and disadvantages of extractions is almost as old as orthodontics
itself, but has resurfaced more recently with all the heat and fury that apparently occurred at the time of Angle vs.
Case (see the articles by Bernstein 1992). In the USA, the debate has on occasion become markedly acrimonious.
It is clearly important to look as objectively as possible at the evidence concerning the issues relating to
extractions.

Reasons for elective extractions in orthodontics
Before examining possible disadvantages of extractions, it is worth reminding ourselves of the reasons for wanting
to remove teeth electively.

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relief of crowding
space is provided for crowded teeth without expanding the arches laterally or anteriorly (or in the
upper arch, without transferring the crowding to a more distal part of the arch).
• correction of incisor relationship
o overjet reduction
o lower incisor retroclination to correct a class 3 relationship
o providing the space required to move upper labial segment contact points distally as
retroclined upper teeth are torqued to a correct inclination in the correction of a class 2 division
ii relationship
o correction of bimaxillary proclination
o increase in overbite if the incisors are proclined and the overbite reduced
• provision of anchorage
in addition to providing the space for tooth movement, extractions frequently provide additional
space which is harnessed to provide intraoral anchorage. Mesial movement of anchor teeth in
response to reciprocal forces is therefore possible without the arch having to be expanded
anteriorly to accomplish the desired occlusion. Without extractions, no intraoral anchorage is
available for distal movement of teeth (except in naturally spaced dentitions or with Temporary
Anchorage Devices - TADs) unless incisors are moved labially in one arch or the other. In nonextraction treatment (discounting unpredictable favourable growth), anchorage must be gained
extra-orally or from TADs or alternatively, incisors must move labially or buccal teeth must expand.
These increases in arch circumference are not always desirable.

Proposed disadvantages of extractions
Several potential disadvantages have been proposed:






mandibular dysfunction
a less attractive dental and facial appearance
longer, more difficult treatment (in some cases)
pain, anxiety and other possible adverse effects of the actual extraction procedure

Key thought:
The last three considerations on this list have all contributed to a general downward trend in the rate of elective
extractions in orthodontics

Extractions and mandibular dysfunction
It has been suggested that extractions may cause mandibular dysfunction by two mechanisms.




the effect on condylar position within the fossa
loss of vertical face height.

Regarding condylar position, such authors as Witzig and Spahl (1987) and Bowbeer (1987) have proposed that
extractions cause “over-retraction” of the upper incisors and that this leads to the condyles being forced
posteriorly and hence the articular disc becomes anteriorly placed and hence mandibular dysfunction. The work
previously quoted in the chapter Occlusal Treatment Goals demonstrates the paucity of evidence of an association
between condylar position and mandibular dysfunction and indeed the inability of orthodontics or restorative
dentistry to alter it permanently. With specific reference to extractions, Gianelly (1991a and 1991b) has found no
difference in condylar position between those treated with the extraction of four premolars and those receiving
no orthodontic treatment. This has been supported by work by Kundinger et al (1991). Luecke and Johnston
(1992) found that the temporary effect of orthodontic treatment on condylar position was highly correlated with
the mesial movement of buccal segments but not at all with the retraction of incisors. Major et al (1997) used
tomography to show that condylar position was unchanged by treatment in both non-extraction and extraction
groups. With regard to the view held, for example, by Bowbeer (1987) that extraction of premolars causes a loss of

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vertical dimension and that this causes mandibular dysfunction, Staggers (1990) was unable to find any such
effect in a study of premolar and second molar extractions. Kocadereli (1999) also found no difference in change
in vertical facial dimensions between 40 cases treated non-extraction and 40 cases treated with first premolar
extractions.
It remains possible that extractions predispose to mandibular dysfunction by some other unknown mechanism.
However, studies by such workers as Kremenak et al (1992) have found no differences between groups treated
with loss of upper premolars, four premolars and non-extraction. Beattie et al (1994) also found no difference in
the CMI values for non-extraction cases and extraction cases. In this clever study, the principle of equipoise was
used to get two groups matched for all the variables which discriminant analysis had shown to be able to account
for the decision to extract or not. In other words, a rare and necessary feat was achieved - to compare the results
of extraction versus non-extraction in groups of comparable cases.
Key Point:
There appears to be very little evidence to support either of the proposed mechanisms for causation of mandibular
dysfunction by extractions or indeed to support any other unknown mechanism. There is therefore no reason to
avoid extractions because of concerns about mandibular dysfunction.

Extractions and facial aesthetics
Orthodontic treatment involving extraction has also been accused of producing unpleasantly retrusive lips
relative to the nose and chin. Studies have certainly shown that it is possible to achieve a degree of long term
retroclination of the lower incisors and that this will be associated with the lips being more posterior than would
have been the case if the incisors were more procumbent. The variability of soft tissue (lip) position for a given
underlying incisor position and the variability of soft tissue response to anteroposterior movement have already
been discussed, but it remains true that for a given individual, more posterior incisors means more posterior lips to
an unpredictable extent. However, studies comparing the soft tissue changes in patients with differing extraction
patterns inevitably encounter the fact that the groups are very unlikely to be balanced in terms of requirements
for space and anchorage. For example, Staggers (1990), comparing first premolar and second molar extractions,
found that the anteroposterior changes in lower incisor position were only minutely different and the soft tissue
changes were very variable, but on average, identical. This would not be at all surprising if the second molar
extraction group had much less initial crowding. This study at least shows that it is nonsensical to generalise
about the effects of extractions on lower incisor position regardless of other features of the malocclusion and
treatment.
Similarly, the studies by Luppanapornlap et al (1993) and by James (1998), both demonstrated that patients
treated with extractions had on average slightly more prominent lips at the end of treatment than those treated
on a non-extraction basis. This reflected the fact that initial lip prominence was a significant factor in the
extraction/non-extraction decision of the orthodontists planning that group of patients. A recent study by Zierhut
et al (2000) again showed the small extra lip retraction with extractions (1.7 mm for the lower lip and 1.0 mm for
the upper lip) when compared with non-extraction cases, but since extractions had been chosen in cases with
slightly more prominent lips, the final average soft tissue profile was identical in both groups. Finally, the study by
Shearn and Woods (2000) was notable for showing the wide variety of anteroposterior changes in lower incisor
position, which result for all combinations of premolar extractions. This is simply a reflection of all the other
variables in the treatment - notably the amount of crowding, of class 2 elastics, of headgear and of differential
growth. An opinion that extractions or non-extraction are “good” or “bad” for the profile is clearly simplistic and
uninformed.
Key point:
All the published data strongly supports the view that orthodontic treatment involving good planning and
execution produces very similar profiles in extraction and non-extraction cases.
Lay opinion
A good study by Bishara and Jakobsen (1997) involved assessment by lay people of profile changes in class 2
division i malocclusions treated with and without extractions. Lay judges:

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preferred the profile of normals to the pre-treatment profile of Class 2 division i patients
immediately after treatment, preferred the changes in profile in the extraction group to the
changes in the non-extraction group
two years after treatment, showed no preference for the profiles of either treatment group or for
the untreated normal group
considered the changes with treatment to be very favourable in both treatment groups.

Key point:
All the published data strongly supports the view that orthodontic treatment with good planning and execution
produces changes in profile which are viewed favourably by the lay public whether or not extractions are involved.
Differences in soft tissue appearance if the same case is treated extraction or non-extraction
Of course, the answers to these questions will also be different for different types of malocclusion. Not much
evidence, as opposed to opinion, exists on any of the questions, but the study by Paquette et al (1992) referred to
above, gave some extremely useful information for one type of malocclusion. The equivalent groups of cases
assembled by the equipoise analysis as being equally susceptible to extraction or non-extraction, were
unsurprisingly, mild to moderate class 2 division i malocclusions with mild lower arch crowding. The cases
averaged 14.5 years post-retention and were recalled and compared aesthetically, for mandibular dysfunction and
for stability. Cephalometric analysis of the long term results revealed that the extraction group had lower incisors
averaging 2 mm more posterior than the non-extraction group and the lower lip was 1.2 mm further behind E line
in the extraction group. However, these measurable and statistically significant differences produced no
detectable aesthetic or stability effects. Regarding aesthetics, various assessments of the patients' opinion of the
aesthetic changes in their silhouettes and facial photographs both before and after treatment revealed no
difference between the groups. Regarding stability, the Little index in the lower labial segment at recall was 2.9
mm in the extraction group and 3.4 mm in the non-extraction group. This difference was again not significant,
although the overall reduction in lower labial irregularity was slightly greater in the extraction group (by 1.9 mm.),
which happened to be slightly more crowded initially and relapsed fractionally less.
It would seem that in such mildly crowded cases, if they are treated using non-extraction mechanics which only
produce mild labial movement of the lower incisors, (average 0.4 mm in this group), it does not matter
significantly whether the cases are treated with or without extractions from the viewpoint of aesthetics or stability.
Twenty years later a very similar study has been reported by Konstantonis (Angle on line early for 2012). The
same equipoise discriminant analysis was used to compare extraction and non-extraction, this time in a sample of
class 1 cases. Analysis showed that the extraction decision was based on initial crowding, facial convexity and
lower incisor protrusion. This confirms that clinicians were basing their extraction decision on actors relating
respectively to stability, facial aesthetics and occlusal fit. Interestingly, the extraction rate in the parent sample was
30% which compared to 55% for the sample treated in the 1970s from which Paquette derived his borderline
group In the derived borderline sample, extraction lead to an average of 2 mm greater retraction of the lower lip
relative to E line and an increase of 5 degrees in the NLA compared to no change for this angle in the nonextraction group. The superimposed average profiles in that paper show that these differences have a small effect
on the facial profile.
These two studies of borderline cases firmly indicate that if it is felt that treatment will be quicker, easier or more
pleasant if carried out on a non-extraction basis, then this would be the sensible approach in this type of case. The
studies did not investigate these latter aspects, but it seems reasonable to assume for now that if all things are
genuinely equal for a given type of case, we should not extract.
An interesting prospective study by Heiser et al (2004), compared two groups with equivalent starting irregularity
index (averaging 5.1 and 5.8) treated with and without premolar extractions. It is very probable that the nonextraction group had some labial movement of the lower incisors relative to the extraction group. They measured
areas bounded by different parts of the dental arch. The increase in the area bounded by the lower labial segment
relapsed more in the non-extraction group, but interestingly, the relapse in Irregularity index was the same in both
groups. The connection between change in lower incisor proclination and irregularity index is clearly not a close

DIAGNOSIS AND TREATMENT PLANNING
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% of cases with > 2mm crowding
Treatment
Extraction

Pre - treatment
16%

25 yrs+
posttreatment
0%

37

one. For relatively mild crowding, treated in the
permanent dentition, extractions possibly confer
no significant additional stability of alignment.

However, the impressive long-term study by
Jonsson
and Magnusson (2010) of cases reviewed
Non-extraction
8%
15%
more
than
25 years after treatment, found that
No treatment
4%
6%
treatments involving extractions produced much
Extraction
16%
11%
less relapse of crowding of greater than 2mm
Non-extraction
3%
28%
Mandible
when compared with non-extraction cases, in
No treatment
9%
16%
both arches but particularly in the lower arch.
Table 3.1:
Jonsson and Magnusson (2010) long term changes in
Such a long-term study is rare and for
crowding. Percentages of cases with > 2mm crowding
understandable
reasons.
The
authors
understandably conclude that non-extraction
cases should receive proportionately more rigorous long-term retention.
Maxilla

In his long-term studies of dental irregularity, Little (1990) identified “lower arch development in the mixed
dentition” (i.e. expansion and proclination of the labial segment) as the only treatment regimen to show
significantly worse results than others in this respect. Little (2002), again referred to this work in his paper
contributing to the section on early treatment which followed the American Association meeting on that subject.
The core of his conclusions was that whilst you can hold and use the Leeway space without any detriment to
stability, lateral and anterior expansion of the arches at an early age caused a degree of relapse which was
“significant and alarming” and this was for cases which only had to have mild proclination to be included in the
“expansion” group. Conversely, a paper by Ferris, Alexander, Boley and Buschang (2005), showed that patients
with mild crowding but significant irregularity, when treated in the late mixed dentition with RME, arch expansion,
interdental stripping and without extractions, had very acceptable stability more than 4 years out of retention.
There was no availability of cephalometric data on incisor labiolingual movement, but the arch width
measurements showed that a substantial percentage of premolar expansion was stable in this age group. The
effect of extraction choices on lateral stability and smile aesthetics is considered below and in the following
chapter on Facial Appearance, the Smile and Tooth Aesthetics. It is worth recalling that Little advocates indefinite
fixed retention after all treatments whatever the final tooth positions.
Extractions and smile width
So far, this section has dealt chiefly with the antero-posterior effects of extractions. Interestingly, the clever study
by Spyropoulos et al.(2001) that used computerised modification of photographs, concluded that factors other
than profile outline may be more important in facial aesthetics for lay people and it is orthodontists who pay
particular attention to the profile. Orthodontic treatment involving extractions has been accused in recent years
of causing larger dark intraoral spaces lateral to the buccal segments - a “dark buccal corridor”. However, the
study by Johnson and Smith (1995) found no evidence of this and also no evidence that extractions produced less
attractive smiles in the opinions of lay judges.
Two more recent studies by Gianelly have looked at the relationship between extractions and width of dentition.
In the first, (Gianelly 2003a), he compared a non-extraction group with an extraction of four first premolars group.
The principal finding was that post-treatment, canine, premolar and widest molar widths were essentially the
same in the two groups. The second similar study (Gianelly 2003b) is more interesting. The first point of note is
that he added a measurement at constant arch depth from the upper central incisors and this depth
corresponded to the average depth of the molar-premolar contact in a group of non-extraction patients. This is a
sound idea, since measurement at a constant arch depth overcomes the problem that non-extraction may well
involve distal movement and therefore molar expansion whilst conversely there is frequently molar constriction in
extraction case just because the molars move mesially into a narrower part of the arch. The results for this
measurement at constant arch depth showed that the extraction group was slightly wider after treatment than
were the non-extraction group. This is a good measurement for future studies. The second part of the study was
similar to that by Johnson and Smith. Fifty lay judges were asked to rate close up photos of 12 extraction and 12
non-extraction smiles. There were no differences in the aesthetic scores between the groups. Interestingly, the
lay judges again seemed unaware of ‘dark buccal corridors’ as an aesthetic factor in smiles, since only one of them

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mentioned it at all. Also there was no difference in the number of teeth displayed in the two groups whilst
smiling.
Key Point:
When comparing extraction and non-extraction cases, measurement of arch width at a constant arch depth
is more informative than measurement of changes in width of a specific tooth
These two studies are similar in many respects to many studies comparing profiles in extraction and nonextraction groups. They are useful in that they look at (and indeed refute) the idea that extraction results in a
narrow arch at the dental smile width, but this leaves unanswered what would result if the same cases were
treated with the two regimens – especially if the space requirements were substantial. The Gianelly studies
naturally involved cases where clinicians had picked horses for courses when choosing to treat extraction or nonextraction. The cases were not matched. One of the conclusions in a thoughtful systematic review by Janson et al
(2011) discussed below is that the studies by Gianelly are good research which does indeed support the view that
premolar extractions per se do not have a detrimental effect on smile aesthetics.
Studies of buccal corridor spaces
Studies using digitally-altered buccal corridor spaces (BCS) are well worth a look, but the results are not yet
strongly convincing. A paper by Moore et al (2005), supported the view that the appearance of small buccal
corridors is preferred by lay judges, whilst the similar study by Roden-Johnson et al (2005), showed no such effect.
Details of study design, such as the extent of the digital alteration or the definition of buccal corridor, are probably
important in these investigations. We feel that the measurement and design used by Moore is the more sound. A
recent study by Yang et al (2008) is also to be recommended for its innovative but very accessible method of
measuring the BCS and found no effect of extractions on BCS. Importantly and understandably, the cases were
not randomised for extraction or matched in any way. The following chapter on Facial Appearance, the Smile and
Tooth Aesthetics gives a thorough overview of smile aesthetics, but it is helpful here to note the study by
McNamara et al (2008), which found no relationship between BCS or upper incisor exposure and smile aesthetics
as rated by both lay persons and orthodontists. Here again, we have to be cautious about that finding because
BCS was measured using the Smilemesh software program which defines BCS as the distance between the
canines and the outer commissure. We would generally prefer to define BCS as the distance from the widest tooth
to the inner commissure. Finally, it is worth looking at the illustrations in the paper by Ioi et al (2009) which also
used digital alteration of BCS. They found that lay judges preferred smaller BCS. However, in our opinion, their
digital manipulation produced a highly unrealistic imitation of a naturally occurring narrow arch, which gave an
appearance of extraction of all buccal teeth. A further point in this paper is that the judges were all orthodontists
and dental students. Genuinely lay judges are much more appropriate in such a study. These were used in a study
by McLeod et al (2011) and interestingly, lay opinion was more fussy in Canada than in the USA about
acceptable limits for BCS and for gum exposure on smiling. The illustrations in that paper clearly show the ideal
and acceptable ranges for these and other smile features. The authors point out that the narrow focus on the
smile area and the specific use of a ‘slider’ to mark the chosen illustrations may well have made the lay judges give
a ore stringent view of acceptability that in real life. This question of realistic portrayal of variations in BCS
concerned Janson et al (2011) in their thoughtful systematic review of factors influencing smile aesthetics. They
concluded that based on studies of actual subjects, BCS on its own has not yet been shown to be a factor in smile
attractiveness.
Key Point:
Interpretation of research requires scrutiny of the actual dimension which was measured and the specific
experimental setup.
Extractions and aesthetics - the study that is needed
There are several good studies discussed above that have compared both profile and smile aesthetics in patients
who have been treated with or without extractions. In all of these studies, the extraction pattern has – very
understandably – not been randomly assigned. Whilst these have been extremely informative, they leave
unanswered the question: “How do the smile and profile aesthetics compare if very crowded cases are treated
with or without extractions?” This question has recently become much more relevant because some clinicians

DIAGNOSIS AND TREATMENT PLANNING
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39

treat virtually everything non-extraction. This change in their practice has in some instances been facilitated by
the apparent ease with which crowded teeth can be accommodated using self-ligating brackets. For this study,
matched cases are required with large space requirements which are treated with or without extractions. Using
the discriminant analysis methods so pertinently applied by Lysle Johnson, such a study must be possible with the
cooperation of clinicians of differing philosophies. The results would still leave the question of the stability of
expansion as a factor in treatment planning, but would more thoroughly examine the aesthetics of arch
expansion.

Planning extractions
In the light of the previous scrutiny of the current evidence, we can now produce suggested guidelines for the
practical implementation of extraction planning (assuming a full complement of healthy teeth). This section is a
series of rules of thumb with supporting explanation and references. It is hoped that this provides a
straightforward sequence of evidence-based thoughts which will produce a sensible extraction plan in the large
majority of cases.

Plan the lower arch first
This adage still seems very sensible as a way of a systematic thought process. However, it should be noted that
factors relating to the upper incisors (such as the NLA) may strongly influence the planned A-P incisor position.
Almost always, if we extract in the lower arch, there is some residual space to close. If the lower incisors are not to
be retroclined (and this is rarely desired), then class 2 traction is required.

Assessing the lower arch crowding
As discussed earlier, the factors which influence a target A-P position for the lower incisors should all be
considered.







A-P incisor stability – even though indefinite retention is planned
facial aesthetics
o profile
o smile width
achievement of a good occlusion
ease of achievement
long-term periodontal health

The amount of crowding is frequently a sufficiently strong factor to narrow the choice by itself to one of two lower
extraction patterns in many cases.
The recommendations in Table 3.2 imply a differential anchorage effect between extraction of first or second
premolars. This differential has long been assumed from the differential force theory, but is supported by a paper
by Saelens and de Smit (1998) where the extraction of first premolars successfully accommodated twice the
crowding than did the extraction of second premolars. The average lower incisor anteroposterior change was the
same in both groups (0 mm) and the molars moved mesially 1 mm more in the second premolar extraction group.
This convincing evidence is supported by the paper by Ong and Woods (2001) which clearly showed more
anchorage is provided in the upper arch by extraction
Category
Millimetres of crowding
Extraction pattern
of 4s than by extraction of 5s. Creekmore (1997),
reviewing this subject concludes that as a rule of
1 to 4 mm
Non-extraction or
Mild
second premolars
thumb, extraction of first premolars provides
5 to 8 mm
First premolars or
Moderate
approximately 66% of the space for aligning/retracting
second premolars
the anterior teeth, whereas extraction of second
9+ mm
First premolars
Severe
premolars provides approximately half of the space.
Table 3.2: Common extraction patterns related to category of crowding.
Other factors may significantly modify this starting point.

Other factors will significantly influence the choice of

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extractions within each category.






desired antero-posterior incisor position (factors listed above)
any planned canine expansion
canine angulation
curve of Spee

The effect on available space of antero-posterior expansion/retraction
The ‘traditional’ rule of thumb is that 1 mm of labial movement will provide sufficient space for 2 mm of crowding
(1mm on each side of the arch). This rule of thumb assumes a rectangular arch form. In fact, with a much more
realistic parabolic archform, the situation is more complicated and in general the labial movement will need to be
greater than 1 mm to produce 2 mm of space. The paper by Steyn et al (1996) demonstrates this and interestingly,
also calculates the effect of different arch depths and widths on the anterior movement of incisors required to
accommodate a given amount of crowding. In general, the wider the intercanine distance and the shallower the
arch depth from the canines to the mid-incisor point, the greater the A-P expansion required to accommodate a
given amount of crowding (or conversely the greater the A-P retraction of incisors for a given amount of
interdental stripping) and in cases presenting a specific dilemma, inspection of the table in the paper by Steyn is
recommended .
In a given instance, the labial movement of lower incisors in a non-extraction case is frequently greater than that
required to accommodate the crowded teeth. This reflects the additional use of class 2 traction and the degree of
control of lower incisor inclination with occlusal plane levelling. For example, in non-extraction cases Saelens and
De Smit (1998) found that to accommodate crowding of only 4 mm required an average of 5 mm of labial
movement of lower incisors and not the 2 mm which the rule of thumb would have estimated. It will be seen in
the chapter on self-ligation that there may possibly be less incisor proclination and greater lateral arch expansion if
light forces and self-ligating brackets are employed to align crowded arches, but this has yet to be supported by
strong evidence.
The effect on available space of lateral expansion
Lateral expansion has been found to have less effect on arch perimeter than A-P expansion. An interesting paper
by Noroozi et al (2002), demonstrates the ability of an algorithm based on two measurements of arch width and
two of arch length to predict the arch perimeter increase which will result for any given A-P or lateral expansion.
These authors again find that A-P expansion is much more effective than lateral expansion in providing space.
Their formula again predicts approximately 1mm of arch length gain for 1mm of incisor labial movement. This is
half of the ‘rule of thumb’. In the lateral dimension, each mm of canine expansion gives 0.6 mm of space and each
mm of second molar expansion gives 0.3 mm.
Key point:
Because dental arches are far from rectangular, 1 mm of labial incisor movement gives approximately 1 mm of extra
arch length, not 2 mm. i.e. more labial movement of incisors is required to accommodate crowding than you might
think.
The amount of curve of Spee
The historical rule of thumb for this factor was 1 mm of space required for every 1 mm depth of curve of Spee.
This has been shown to be an excessive calculation of space required. Germane and Staggers (1992) found a nonlinear relationship and a less than one to one ratio for curves shallower than 9 mm. A more recent study by Braun
et al (1996) found an even smaller effect - namely that a very deep curve of 9 mm only requires 2 mm of additional
space. The strong tendency for labial flaring of lower incisors associated with non-extraction levelling of curves of
Spee is therefore mainly due to choices in the biomechanics employed rather than to the space requirements.
This will be discussed further in the chapter on Managing Overbites and is also referred to in the section on bracket
prescriptions in the chapter on The Development of Preadjusted Appliance Systems.

DIAGNOSIS AND TREATMENT PLANNING
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41

If the lower arch is non extraction:-

Then non-extraction is our treatment of choice in the upper arch. If the case is suitable for functional appliance
treatment then this is our preferred option if class 2 correction is required. If the upper second molars have
erupted, the upper third molars are present and of good size and at least half a unit of distal movement is
proposed, then the extraction of upper second molars can be considered. Waters (2001) has reported that this
achieved 1.2 mm additional distal movement of the upper first molar and 5 degrees less incisor proclination, but
this should be weighed against the long -term disadvantage of having a smaller more conically rooted third molar
in place of a second molar. We almost never extract upper or lower second molars. (One exception is when
intruding molars with TADS in the presence of unerupted 8s).
Although non-extraction is our treatment of choice if the lower arch is non-extraction, extraction of upper first
premolars is much less demanding on anchorage and the occlusal disadvantages of a class 2 molar relationship
are slight (see Andrews 1989: Straight Wire: The Concept And Appliance pages 182-187). If the initial molar
relationship is more than half a unit class 2 and the case is not ideal for functional appliances, we would usually
advocate extraction of upper first premolars. This does carry an increased chance of small residual spaces in the
extraction sites. This is due partly to the difference in mesiodistal width between two premolars and one first
molar and partly to the second premolars being teeth that are more frequently disproportionately small. This was
discussed in the chapter on Occlusal Treatment Goals. Such occlusal imperfections may be considered much more
acceptable than the consequences of insufficient anchorage to correct a class 2 relationship. A recent new factor
in this decision between aiming for a class 1 or class 2 molar relationship is our ability to distalise buccal segments
with miniscrews (See chapter on Temporary Anchorage Devices in Orthodontics)

If lower premolars are extracted:Then upper premolars are almost always extracted. If the upper canines are at an ideal angulation or more distally
angulated and must move distally by half a unit or more, then extraction of upper first premolars is recommended.

Therapeutic diagnosis

Extractions are irreversible. Treatment response can be unpredictable. In a number of cases, it is sensible to start
non-extraction and align the arches before making a decision on extraction. If extractions are then carried out,
very little treatment time has been lost and the need for the extractions has been demonstrated to clinician and
patient. The potentially different response to alignment with very gentle wires and self-ligating brackets has in
our view increased the occasions when this approach is sensible. It is important to start such treatment with the
clear understanding that if the clinician decides after some visits that extractions are required that this is a
decision that must be implemented.

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Angle Orthodontist 79: 628-636
James RD (1998)
A comparative study of facial profiles in extraction and non-extraction treatment
American Journal of Orthodontics and Dentofacial Orthopaedics 114: 265-76
Janson G, Branco NC, Fernandes TMF, Sathler R, Garib D, Lauris JRP(2011)
Influence of orthodontic treatment, midline position, buccal corridor and smile arc on smile attractiveness
Angle Orthodontist 81: 153-161
Johnson DK and Smith RJ (1995)
Smile aesthetics after orthodontic treatment with and without extraction of four first premolars
American Journal of Orthodontics and Dentofacial Orthopaedics 108: 162-7
Jonsson T and Magnusson TE (2010)
Crowding and spacing in the dental arches: long term development in treated and untreated subjects
American Journal of Orthodontics and Dentofacial Orthopaedics 138:384e1-384e7
Johnston C, Burden D, Kennedy D, Harradine N, Stevenson M (2006)
Class III surgical-orthodontic treatment: A cephalometric study
American Journal of Orthodontics and Dentofacial Orthopaedics 130:300-9
Johnston LE (1996)
Balancing the books on orthodontic treatment: an integrated analysis of change
British Journal of Orthodontics 23: 93-102
Johnston LE (1998)
The value of information and the cost of uncertainty: who foots the bill?
Angle Orthodontist 68: 99-102
Kocadereli İ (1999)
The effect of first premolar extraction on vertical dimension
American Journal of Orthodontics and Dentofacial Orthopaedics 116: 41-45
Konstantonis D (online early for 2012)
The impact of extraction vs nonextraction treatment on soft tissue changes in Class I borderline malocclusions
The Angle Orthodontist
Kremenak CR, Kinser DD, Harman HA, Menard CC and Jakobsen JR (1992)
Orthodontic risk factors for temporomandibular disorders (TMD) 1:premolar extraction
American Journal of Orthodontics and Dentofacial Orthopaedics 101:13-20
Kundinger KK, Austin BP, Christensen LV, Donegan SJ, Ferguson DJ et al (1991)
An evaluation of temporomandibular joints and jaw muscles after orthodontic treatment involving premolar
extractions.
American Journal of Orthodontics and Dentofacial Orthopaedics 100: 110-115
Kusnoto J and Kusnoto H (2001)
The effect of anterior tooth retraction on lip position of orthodontically treated adult Indonesians
American Journal of Orthodontics and Dentofacial Orthopaedics 120: 304-307
Lai J, Ghosh J and Nanda RM (2000)
Effects of orthodontic therapy on the facial profile in long and short vertical facial patterns
American Journal of Orthodontics and Dentofacial Orthopaedics 118: 505-13
Little RM (1990)
Stability and relapse of dental arch alignment
British Journal of Orthodontics 17:235-41

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EXCELLENCE IN ORTHODONTICS 2012

Little RM, Riedel RA and Stein A (1990)
Mandibular arch length increase during the mixed dentition. Post retention stability and relapse.
American Journal of Orthodontics and Dentofacial Orthopaedics 97: 393-404
Little RM (2002)
Stability and relapse: early treatment of arch length deficiency
American Journal of Orthodontics and Dentofacial Orthopaedics 121:578-581
Livieratos FA and Johnston LE Jr. (1995)
A comparison of one-stage and two-stage non-extraction alternatives in matched Class II samples.
American Journal of Orthodontics and Dentofacial Orthopaedics. 108:118-31
Luecke PE and Johnston LE (1992)
The effect of maxillary first premolar extraction and incisor retraction on mandibular position: testing the central
dogma of “functional orthodontics”
American Journal of Orthodontics and Dentofacial Orthopaedics 101: 4-12
Luppanapornlap S and Johnston LE (1993)
The effects of premolar extraction: a long term comparison of outcomes in “clear-cut” extraction and non-extraction
Class II patients
Angle Orthodontist 63: 257-272
Major P, Kamelchuk L, Nebbe B, Petrikowski G and Glover K (1997)
Condyle displacement associated with premolar extraction and non-extraction orthodontic treatment of Class I
malocclusion
American Journal of Orthodontics and Dentofacial Orthopaedics 112: 435-40
McLeod C, Fields HW, Hechter F, Wiltshire W, Rody W and Christensen J (2011)
Esthetics and smile characteristics evaluated by laypersons
Angle Orthodontist 81: 198-205
McNamara L, McNamara JA, Ackerman M, Baccetti T (2008)
Hard- and soft-tissue contributions to the aesthetics of the posed smile in growing patients seeking orthodontic
treatment
American Journal of Orthodontics and Dentofacial Orthopaedics 133: 491-499
Merrifield LL (1966)
The profile line as an aid in critically evaluating facial aesthetics
American Journal of Orthodontics 52: 804-822
Mills JRE (1966)
Long-term results of the proclination of lower incisors
British Dental Journal 120: 355-363
Mills JRE (1968)
The stability of the lower labial segment
Dental Practitioner 18: 293-306
Moore T, Southard K, Casko JS, Qian F, Southard TE (2005)
Buccal corridors and smile aesthetics
American Journal of Orthodontics and Dentofacial Orthopaedics 127:208-13
Nomura M, Motegi E, Hatch JP, Gakung PT, Ng’ang’a PM, Rugh JD, Yamaguchi H (2009)
Esthetic preferences of European American, Hispanic American, Japanese, and African judges for soft-tissue profiles
American Journal of Orthodontics and Dentofacial Orthopaedics 135: S87-S95
Noroozi H, Djavid GE, Moeinzad H and Teimouri AP (2002)
Prediction of arch perimeter changes due to orthodontic treatment.
American Journal of Orthodontics and Dentofacial Orthopaedics 122:601-607
O’Brien K et al (2003)
The effectiveness of early treatment for Class II malocclusion with the Twin Block appliances: A multicentre
randomized controlled trial. Part 1:dental and skeletal effects
American Journal of Orthodontics and Dentofacial Orthopaedics 124:234-43
Ong HB and Woods MG (2001)
An occlusal and cephalometric analysis of maxillary first and second premolar extraction effects
Angle Orthodontist 71: 90-102
Pancherz H and Anehus-Pancherz M (1993)
The headgear effect of the Herbst appliance: A cephalometric long-term study
American Journal of Orthodontics and Dentofacial Orthopaedics 103: 510-520

DIAGNOSIS AND TREATMENT PLANNING
EXCELLENCE IN ORTHODONTICS 2012

Paquette DE, Beattie JR and Johnston LE Jr (1992)
A long-term comparison of non-extraction and premolar extraction edgewise therapy in “borderline” Class II patients.
American Journal of Orthodontics and Dentofacial Orthopaedics 102: 1-14
Park and Burstone (1986)
Soft - tissue profile - fallacies of hard tissue standards in treatment planning
American Journal of Orthodontics 90: 52-56
Roden-Johnson D, Gallerano R and English J (2005)
The effects of buccal corridor spaces and arch form on smile aesthetics
American Journal of Orthodontics and Dentofacial Orthopaedics 127:343-50
Sarver DM and Ackerman MB (2003a)
Dynamic smile visualisation and quantification: Part 1. Evolution of the concept and dynamic record for smile capture
American Journal of Orthodontics and Dentofacial Orthopaedics 124:4-12
Sarver DM and Ackerman MB (2003b)
Dynamic smile visualisation and quantification: Part 2. Smile analysis and treatment strategies
American Journal of Orthodontics and Dentofacial Orthopaedics 124:116-27
Saelens NA and De Smit AA (1998)
Therapeutic changes in extraction versus non-extraction orthodontic treatment
European Journal of Orthodontics 20:225-230
Selwyn-Barnett BJ (1996)
Class II/Division 2 Malocclusion: A method of Planning and Treatment
British Journal of Orthodontics 23: 29-36
Sims AP and Springate SD (1995)
Stability of the lower labial segment following orthodontic treatment--a comparison of treatment with Andresen and
Begg appliances
British Journal of Orthodontics 22: 13-21
Shearn BN and Woods MG (2000)
An occlusal and cephalometric analysis of lower first and second premolar extraction effects
American Journal of Orthodontics and Dentofacial Orthopaedics 117:351-61
Spahl TJ
Letter to the editor
American Journal of Orthodontics and Dentofacial Orthopaedics (2003); 124:16A-17A
Spyropoulos MN and Halazonetis DJ (2001)
Significance of the soft tissue profile on facial aesthetics
American Journal of Orthodontics and Dentofacial Orthopaedics 119: 464-71
Staggers JA (1990)
A comparison of second molar and first premolar extraction treatment.
American Journal of Orthodontics and Dentofacial Orthopaedics 98: 430-436
Stephens CD and Houston WJB (1985)
Factors affecting the rate of spontaneous space closure at the site of extracted mandibular first premolars
European Journal of Orthodontics 7: 157-62
Steyn CL, Harris AMP and du Preez RJ (1996)
Anterior arch circumference adjustment - how much?
Angle Orthodontist 66: 457-462
Stucki N and Ingervall B (1998)
The use of the Jasper Jumper for the correction of Class II malocclusion in the young permanent dentition
European Journal of Orthodontics 20: 271-281
Tadic N and Woods MG (2007)
Incisal and soft tissue effects of maxillary premolar extraction in class II treatment (2007)
The Angle Orthodontist 77: 808–816
Waters D and Harris EF(2001)
A cephalometric comparison of maxillary second molar extraction and non-extraction treatment in patients with Class
2 malocclusions
American Journal of Orthodontics and Dentofacial Orthopaedics 120: 608-613
Williams S and Andersen CE (1995)
Incisor stability in patients with anterior rotational mandibular growth
Angle Orthodontist 65: 431-442

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DIAGNOSIS AND TREATMENT PLANNING
EXCELLENCE IN ORTHODONTICS 2012

Witzig JW and Spahl TJ (1987)
The clinical outline of maxillofacial orthopaedic appliances
1st ed. Littleton, Mass: PSG Publishing: 167-216
Yang I-H, Nahm DS and Baek H-S (2008)
Which hard and soft tissue factors relate with the amount of buccal corridor space during smiling?
The Angle Orthodontist; 78: 5–11
Zierhut EC, Joondeph DR., Artun J and Little RM (2000)
Long-term profile changes associated with successfully treated extraction and non-extraction Class II division I
malocclusions.
Angle Orthodontist 70: 208-219

Useful related references not referred to in this chapter
Proffitt WR (1994)
Forty-year review of extraction frequencies at a University orthodontic department
Angle Orthodontist 64: 407-413

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