T H E B E L L E M A U D S L E Y L E C T U R E 2 0 0 2

The Timing of Orthodontic

Treatment
ANDREW DIBIASE

l Will the final result of two-phase

Abstract: The time at which orthodontic treatment should be started remains a treatment be better than that of a
matter of conjecture. Anomalies of dental development and functional problems tend to
single course of treatment at a later
be addressed in the mixed dentition, while definitive treatment tends to be delayed
until the late mixed dentition to maximize growth potential and patient compliance. stage?
However, some clinicians advocate starting treatment earlier in certain types of l Will early treatment reduce the risk
malocclusion. In this article, the current concepts of early treatment, both physiological of trauma to susceptible incisors?
and psychological, will be explored and the relevant indications and contraindications l Will early treatment result in greater
discussed. skeletal change than treatment
during the growth spurt?
Dent Update 2002; 29: 434–441 l Will early treatment reduce the
Clinical Relevance: General dental practitioners need to have an understanding of severity of the problem to make a
the timing of orthodontic treatment in different types of malocclusion to maximize the second phase of treatment easier
effectiveness of patient referrals. and of a shorter duration?
l Will early treatment create problems
or reactions that are undesirable?
l Will early treatment have a
beneficial psychological impact on

W ithin the practice environment,

dentists are the first to examine
and screen children for developing
of the wisdom teeth, the developing
dentition should be monitored and
interceptive treatment prescribed as
the patient?

malocclusions. They are often faced with necessary. There is a difference, however,
Early mixed dentition:
the dilemma of deciding at what age to between treatment decisions that are l Delayed eruption of permanent incisors
refer for a further opinion and possibly thrust upon us due to aberrations of l Supplemental incisors
treatment. This of course depends on the dental development and types of l Early loss of deciduous teeth
l Congenital absence of incisors
problem that has been diagnosed and the malocclusion that we may choose to treat l One or more incisors in crossbite
dental development of the child, but is early by use of appliance therapy or l Impaction of first permanent molars
there an ‘ideal’ time for orthodontic elective extraction of teeth. Table 1 lists l Severe crowding
l Severe skeletal discrepancy
treatment, if the clinician wants to the problems that should be looked for at l Posterior crossbites
maximize the benefits of growth and co- various stages of dental development.
operation without subjecting every child It is obvious from these lists that the Late mixed dentition:
l Severe skeletal problems
to four or more years of treatment? management of certain problems such as l Unfavourably positioned canines or
skeletal discrepancies or crowding can be other teeth
undertaken at differing times during the l Congenitally absent permanent teeth
MANAGING THE l Poor-quality first permanent molars
dental development. When early l Traumatic overbites
DEVELOPING DENTITION treatment is contemplated, especially if it
From the eruption of the first primary involves the use of active appliances, the Early permanent dentition:
l Severe skeletal problems
tooth until the development and eruption following questions should be asked:1 l Impacted teeth
l Crowding
l Will early treatment correct the l Hypodontia
Andrew DiBiase, BDS(Hons), MSc, FDS(Orth), problem or eliminate the need for
MOrth RCS(Eng), Consultant Orthodontist, Kent Table 1. Problems to look for in the developing
and Canterbury Hospital, Canterbury. comprehensive treatment at a later dentition in relation to timing of orthodontic
date? treatment.

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 B E L L E M A U D S L E Y L E C T U R E

before eruption of the canines to allow

a b
alignment of the labial segments,
however, remains a common practice.
The advantages of this are that it allows
for spontaneous alignment of
labiolingual displacement of the incisors
(especially in the lower arch), if the
canines are mesially inclined.2 In the
upper arch there is little or no
spontaneous alignment of the incisors,
c but early loss of first premolars when
the canines are unerupted, buccally
Figure 1. Class II division 2 malocclusion with displaced and short of space will allow
crowding: (a) right buccal view; (b) labial view; for eruption of these teeth into the line
(c) left buccal view. of the arch. There is evidence that early
extraction of first premolars, followed by
active appliance therapy, results in less
lower incisor irregularity than treatment
with first premolar extractions and fixed
appliances, once all the permanent teeth
(except the second molars) have
It is also important to differentiate canines are often extracted early in the erupted.3
between interceptive and definitive hope of correcting the palatal If non-extraction treatment is planned
treatment: interceptive treatment is displacement of their permanent and begins before loss of the second
intervening in the developing dentition successors. A more elective choice is deciduous molars, in the lower arch the
to allow it to achieve the best occlusion the early extraction of teeth for the leeway space can be used for relief of
possible, or to make subsequent relief of crowding. This can range from crowding, as shown in Figures 1–3. If a
treatment as simple and short as the removal of upper primary canines to lingual arch is placed during the mixed
possible. Therefore, although certain create space for upper lateral incisors dentition only an arch length decrease
problems may be addressed earlier, there and stop them erupting into crossbite, of 0.44 mm has been reported, leaving an
is a difference between a 6-month to serial extraction. The latter procedure average of 4.44 mm leeway space.4 This
course of treatment in the mixed is rarely undertaken in its entirety now allowed for the resolution of crowding in
dentition followed by later treatment in that comprehensive appliances are more 60% of 107 patients with an average of
the early permanent dentition and a readily available. Early extraction of 4.85 mm crowding at the start of
definitive course of treatment that premolar units in the late mixed dentition treatment. It must be remembered,
commences in the mixed dentition and
extends over several years.

a b
EARLY MANAGEMENT OF
TOOTH SIZE/ARCH SIZE
DISCREPANCIES
Historically, the enforced early loss of
deciduous teeth (usually due to caries)
often necessitated a decision whether to
balance (to maintain the centre line) or
compensate (to maintain the buccal
relationship) with further extractions, c
especially when crowding was present.
The advances in restorative techniques Figure 2. Treatment for the dentition shown in
in paediatric dentistry and the more Figure 1: commencement before loss of lower
universal availability of comprehensive second deciduous molars: (a) right buccal
treatment with fixed appliances has view; (b) labial view; (c) left buccal view.
meant these procedures tend to be
carried out less and less. Conversely,
current practice dictates that deciduous

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 B E L L E M A U D S L E Y L E C T U R E

intercanine region, typically decreases

a b after treatment, regardless of whether a
case was expanded during treatment or
not. This results in higher degrees of
relapse in cases where there has been
enlargement of the mandibular arch.6

EARLY MANAGEMENT OF
POSTERIOR CROSSBITES
c Crossbites with displacement are
generally thought to be a functional
Figure 3. Dentition shown in Figure 1 at end indication for early orthodontic
of active treatment: after 22 months: (a) right treatment. The aim is to stop the
buccal view; (b) labial view; (c) left buccal crossbite becoming established in the
view.
permanent dentition, as crossbites with
displacement are one of the few
occlusal traits that have a slight
association with the development of
temporomandibular joint dysfunction
later in life.7 There is evidence of
however, that in patients in the primary spacing in the primary dentition as the asymmetric muscle activity and altered
dentition there is often a straight permanent maxillary and mandibular bite force in children with a posterior
terminal plane at the distal aspect of the first molars erupt, the space mesial to crossbite with displacement.8,9
second deciduous molars. If there is lower deciduous molars lets these teeth Treatment in the primary or early mixed
move forward, allowing the permanent dentition by selective grinding and
molars to erupt into a Class I active expansion with a removable plate
relationship. This is called an early is thought to decrease the risk of the
mesial shift (Figure 4). However, if there crossbite being perpetuated to the
is no spacing between the deciduous permanent dentition.10
teeth (i.e. a closed primary dentition),
there is no mesial movement of the
mandibular deciduous molars as the
permanent molars erupt, and they erupt
into a cusp-to-cusp relationship. The
mandibular leeway space therefore
allows for mesial migration of the lower
first molars into a Class I relationship
as the deciduous molars are shed. This
is called a late mesial shift (Figure 5).
Therefore, if lower arch length is
preserved to use the leeway space to
relieve crowding, correction of the
molar relationship will require
distalization of the maxillary first
molars, often using headgear.
Crowding is thought to be related to
the dimension of the dental arches in
that the greatest crowding exists in the
narrower arches.5 This has led some
clinicians to advocate active expansion
of the arches in the mixed dentition in
an attempt to create space to
accommodate the complete dentition.
Figure 4. Early mesial shift in spaced Unfortunately, it appears that lower Figure 5. Late mesial shift in closed primary
primary dentition. arch width, particularly in the dentition.

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 B E L L E M A U D S L E Y L E C T U R E

whether treatment is successful is the

a b underlying growth pattern, which tends
to re-impose itself following treatment,
especially mandibular prognathism.

EARLY MANAGEMENT OF
CLASS II MALOCCLUSIONS
There is currently a resurgence in
Figure 6. Correction of anterior crossbite with removable appliance. interest in the concept of two-phase
treatment: early use of functional
appliances in the mixed dentition,
followed by a period of retention and
One factor that encourages early relationships have been described, then a second phase of treatment,
treatment is the fact that correction can including the use of functional usually involving the use of fixed
often be achieved very simply with appliances16,17 (Figures 8–10), appliances. The advocates of early
removable appliances and minimal protraction headgear,18,19 chin caps20 treatment feel that starting early will
patient compliance within a reasonably and headgear to the lower arch.21 All of maximize the chances of growth
small time period. As such it is a these treatment modalities surprisingly modification (especially in female
procedure that can often be carried out seem to have similar clinical effects: patients who tend to reach their
in general practice. Although fixed proclination of the upper incisors, skeletal maturity earlier), allow for two
expansion devices such as the retroclination of the lower incisors and chances to correct the malocclusion
quadhelix may result in orthopaedic as rotation of the mandible downwards and avoid problems of compliance
well as orthodontic expansion,11 there and backwards. There also appears to often encountered in adolescents.22
is evidence that removable appliances be a slight anterior movement of the It has been shown, however, that the
and quadhelices produce similar maxilla when protraction headgear is skeletal contribution to correction of
amounts of dental and skeletal used, especially when accompanied by Class II division 1 malocclusions
expansion and have similar relapse palatal expansion.18 The skeletal effects treated with twin blocks is greater if
rates,12 but that the use of removable of protraction headgear also appear to treatment is carried out during or
appliances with midline expansion be greater in pre-adolescent patients.19 slightly after the onset of the pubertal
screws may result in less buccal tipping Early treatment of Class III peak in growth velocity.23 Similar
of the posterior teeth.13 Rapid maxillary malocclusions is generally not findings have been reported for the
expansion has been found to produce successful in cases with increased Bass appliance,24 the Herbst appliance25
more bodily movement of teeth.12 lower face height and minimal and the FR-2 appliance.26 Further
overbites. The overriding factor in research has also shown that the early

EARLY MANAGEMENT OF
CLASS III MALOCCLUSIONS
The correction of anterior crossbites in a b
the mixed dentition may prevent loss of
periodontal attachment of the lower
incisors. If only one or two incisors are
in crossbite and there is adequate
space available, a removable appliance
can often be used14 (Figure 6): if space
needs to created and more bodily
movement of teeth is required, better
results may be achieved with simple c
fixed appliances15 (Figure 7). The
success of either depends on creating a Figure 7. Correction of anterior crossbite with
positive overbite at the end of fixed appliance.
treatment.
Both the above scenarios primarily
relate to skeletal I or mild skeletal III
relationships. Other methods of early
correction of severe skeletal

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 B E L L E M A U D S L E Y L E C T U R E

removable appliance will help to

a b
maintain the sagittal correction and
allow the lateral open bites to improve
as the dentition develops.37

EARLY TREATMENT AND

COMPLIANCE
Another factor that has been used to
favour early treatment is the greater
compliance obtained from pre-
Figure 8. Class III malocclusion with anterior
displacement on closing. adolescent patients. This has certainly
been reported for adherence to
instructions given for removable
appliances38 and for headgear wear,39
although some studies have found no
correlation between patient’s age and
use of functional appliances has little communication). Figures 11–13 show the level of co-operation.40,41 Younger
or no long-term benefit in terms of case of a patient in the mixed dentition children are usually influenced by their
enhanced growth or better outcome who requested treatment as a result of parents and other adults but
over later one-stage treatment.27,28 concerns about teasing at school. adolescents are more susceptible to
So, if there are no advantages in early One consistent finding is the peer pressure, especially in terms of
treatment physiologically, are there any increased incidence of trauma to the self-image. Of course this can act in
psychological advantages? There is upper labial segment in pre-adolescent either direction when trying to
substantial evidence that the dental children with increased overjets.34,35 encourage compliance to orthodontic
appearance has an effect on social Increased overjet appears to be a greater treatment: if an adolescent has
perceptions and interaction,29 and can contributor to traumatic injury in girls significant concerns about the
be a target of teasing.30 The negative than boys, even though traumatic injury appearance of his or her teeth and has
impact of malocclusion on self- frequency is greater in boys.35,36 A high
perception appears to increase with percentage of these injuries occur
age.31 Despite this, early treatment for before the age of 10 years, especially in
Class II malocclusion has been reported boys34 (probably due to the rougher a
to have no effect on self-concept,32 nature of boys’ activities and their more
although within this study the children active participation in sports).35
looked at did not present for treatment An advantage of starting functional
with low self–concept in the first place. appliance therapy in the late mixed or
This is supported by other work which permanent dentition is that the
found that pre-adolescent children functional phase of treatment can be
awaiting orthodontic treatment generally followed almost immediately by the fixed
have higher than average self-concept.33 appliances, which can incorporate
More recent work, however, may show mechanics designed to stabilize the
that early treatment increases self- newly established occlusion. By starting
esteem (K. O’Brien, personal treatment in the mixed dentition, there
will inevitably be a period when the
clinician is awaiting further dental
b
development before further treatment
decisions can be made. This will mean
either that treatment will have to be
discontinued during this period or that
some form of retention regime will have
to be implemented. This may consist of
wearing the appliances just at night, the
use of headgear or the use of simple
removable retainers. If the last policy is
pursued, incorporation of an inclined Figure 10. Patient shown in Figure 8 at end of
Figure 9. Class III Twin Block appliance used to active treatment, after 6 months.
treat the malocclusion shown in Figure 8. anterior bite plane on an upper

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 B E L L E M A U D S L E Y L E C T U R E

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 B E L L E M A U D S L E Y L E C T U R E

early treatment, however, is often the

a b
requirement for a second phase of
treatment in the early permanent
dentition. Whether the compliance
during this second stage of treatment is
affected by starting treatment in the
mixed dentition is unknown.

CONCLUSIONS
Figure 11. Class II division 1 malocclusion l Expansion of the lower arch in mixed
with lip incompetence and increased incisor dentition to address crowding is
show at rest. inherently unstable.
l When correctly planned, early
extraction of teeth for the relief of
crowding may result in increased
a b long-term stability – particularly in
the lower labial segment – and
simplify appliance mechanics during
active treatment.
l Treatment in the mixed dentition is
indicated for anterior and posterior
crossbites with displacements on
dental health grounds.
l If protraction headgear is planned
for treatment of Class III
Figure 12. Patient shown in Figure 11 during malocclusions, treatment should
treatment with high pull headgear and Bass
commence in the mixed dentition for
functional appliance.
maximum benefit.
l Early treatment with functional
appliances for Class II division 1
malocclusions does not appear to
a b result in greater skeletal change
than later treatment, and does not
appear to offer any psychological
benefits in the average child.
l Risk of trauma to the upper labial
segment may justify early treatment
of Class II division 1 malocclusions,
especially in girls.
l Most orthodontic treatment can be
started in the late mixed dentition
Figure 13. Patient shown in Figure 11: end of
active treatment (after 14 months). just before loss of the primary
mandibular second molar. This will
maximize growth potential and
compliance, allow for utilization of
the leeway space and keep overall
active treatment time as short as
friends who are undergoing ‘here and now’.33 This age group is possible .
orthodontics, the treatment will have generally aware of the reason for
peer acceptance and compliance may referral for orthodontic treatment, and
be forthcoming; however, if no peers understands the perceived benefits of
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 B E L L E M A U D S L E Y L E C T U R E

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