Current controversies in orthodontics /certified fixed orthodontic courses by Indian dental academy
INDIAN DENTAL ACADEMY
Leader in continuing dental education
Orthodontics, Dentistry’s first speciality is rich in it’s
history and also in it’s controversy. Controversies unlike
disputes never end. They cannot be settled totally by
scientific evidence substantiating any one side of the
Esthetic need for orthodontic treatment
Classification of malocclusion
Retention and relapse.
The extraction – non extraction controversy is the oldest and most
enduring controversy in orthodontics. The controversy is still alive today almost
90 years since it first started. The controversy was between the Angle’s school of
thought and it’s followers like Martin Dewey and Calvin Case who believed in
In a 1902 article, Angle sets forth his line of reasoning toward the
development of his treatment philosophy. In this article he recounts his
conversations with his friend, the artist Edmund Wuerpel, whose help led to his
concepts of facial beauty and harmony. He believed that all humans were
created to have a full complement of natural teeth which would go hand in hand
with an ideal occlusion and a harmonious face. He idealized an occlusion thus
which contained a full compliment of well aligned teeth which occluded along his
line of occlusion.
It is first of all evident from the statements of Angle that his philosophic
basis was creationist dogma rather than ideals backed by strong scientific
The battle was really begun in 1911 in what has become to be known
as "The Extraction Debate of 1911." At the 1911 meeting of the National Dental
Association, Calvin Case presented an article entitled "The Question of
Extraction in Orthodontia," .
In the article Case strongly criticizes the creationist belief of the Angle
school and their disregard of heredity as a cause or malocclusion and their
belief that all causes of malocclusion were local and replacing teeth in their
intended positions would lead to a harmonious face.
To substantiate the case further he presented a patient whose dental
protrusion would have worsened had a non extraction treatment had been
done. Thus emphasizing that all cases cannot be treated non extraction to
achieve a harmonious face.
DID ANGLE REALLY PRACTICE WHAT HE
Earlier, in 1887, Angle wrote on his new system to regulate and
retain the teeth. In that same year, the first edition of his book on the
same subject was published. Other editions supposedly followed up to
1897 when the fifth edition, expanded in scope, came out. This was
followed by the enigmatic sixth edition, which was supposedly withdrawn
by Angle from publication. This edition, which has never been referred to
previously in the literature as, and seems never to have been referred to
in lectures by Angle and/or his supporters, is enigmatic because of the
large number of extraction cases presented in it.. However, what is even
more fascinating is that the subsequent seventh edition which was
published was completely stripped of all the extraction case material
present in the sixth edition.
The battle ironically was finally won by Charles Tweed a student of
Angle who in 1952 presented case reports of patients who were treated initially
non extraction using Angles treatment philosophies and were later retreated with
a all first premolar extractions. The Tweed philosophy was born and extractions
were finally accepted into orthodontics due to the great work of Tweed which
provided scientific evidence towards the need of extraction in treatment.
Around the same time Begg in Australia was developing another
appliance system which was also based on therapeutic exraction. Begg
developed his appliance on the theory of attritional occlusion. It should be noted
here that though both Tweed and Begg believed in therapeutic extraction Tweed
had a more scientific basis to back his technique whereas Begg only had a
theory – the attritional occlusion theory to justify his extractions.
With the development of the Tweed edgewise philosophy and the Begg
appliance came a period in orthodontics where premolars were indiscriminately
extracted for correction of malocclusion. This lead to unfavorable facial
Now with orthodontists paying more importance to facial harmony and
esthetics the indiscriminate extraction of premolars have been reduced and with
Advance in mechanotherapy the use of non extraction therapy is now on the rise.
Wick Alexander now claims only 10% of his cases are treated with extraction and
the rest being treated non extraction. Norman Cetlin who used to treat 95% cases
with extraction treats only 10% with extraction.
The current dogma against non extraction treatment is:
• upper molars cannot be distalised bodily.
•Arches cannot be expanded in any direction.
•Lower canine width cannot be increased.
•Long term retention is necessary for stability.
However currently non extraction treatment is confined to the following cases:
•8mm or less of crowding
•Severely mesially and lingually tipped posterior teeth.
•Cooperative and growing patients.
Though the extraction – non extraction controversy may not be plagued by
as much as dogmas as it was almost 100 years ago both treatment options are still
open. With improved biomechanical appliances it is more possible to move molars
bodily. Studies by De Paoli have shown that increased mandibular canine width
achieved using a lip bumper along with a Cetlin appliance are found to be stable in
the long run provide they are used during a period when the inter canine width is
developing. The amount of arch expansion though seems to be limited.
the option to treat either extraction or non extraction should be made
objectively for each case based on strong evidence rather on some ones opinion
‘that it woks’
The use and mode of action of functional appliance is shrouded in
controversy. The reason behind this is because of the different philosophies and
basis on which each designer constructed his appliance. There may not be a
specific modus operandi behind all functional appliances.
But do functional appliances work in the first place…? – as they are
intended to. Or is natural growth responsible for the changes. And even if they
do are the changes produced clinically significant?
An interesting incident is quoted in Birte Melsen’s texbook on
controversies in orthodontics. A patient with severe Class II and horizontal
growth pattern was given a FR II. The patient had an impressive class II
correction in six months. the only problem was that the patient carried the
appliance in her purse during the course of treatment.
The controversies discussed here will be in relation to :
• modus operandi of functional appliance
•Growth changes with functional appliances.
Modus operandi of functional
Functional appliances evolved from different concepts of
the interrelationship between the orofacial musculature ,
dentition and plasticity of growth. Each led to a working
hypothesis expressed as an appliance design.
It was Kingsley who first used a vulcanite maxillary
appliance that repositioned the mandible anteriorly and
guided dental eruption in an attempt to “jump the bite” as
he termed it.
The classic monobloc was used by Pierre Robin at the
beginning of the twentieth century to treat the
glossoptotic syndrome. But it was later found that these
patients will usually have a period of spontaneous “catch
up” growth with or without appliance therapy.
Andresen of Norway modified the Kingsley vulcanite eruption control
appliance to “activate” the musculature to create a functionally
favorable environment for functionally induced anatomical change.
The working hypothesis behind the Andresen activator was that the
protractor muscles of the mandible could be stimulated or
“activated” to assist in achieving a dental saggital correction.
The isotonic contractile forces of the stretched muscles were
transmitted to the teeth in contact with the appliance.
The Andresen appliance was intended as a functional appliance for
dento alveolar correction only. A dentofacial orthopedic correction
which may have been a side effect was not part of his original
The effects of the activator were substantiated by Pancherz when
he studied 30 patients treated with the activator activator treatment
seemed to inhibit maxillary growth, move the maxillary incisors and
molars distally, and move the mandibular incisors and molars
mesially. Mandibular growth appeared not to be affected by
Thus by way of contraction of the muscles to keep the loosely fitting
appliance in place intermittent forces are transmitted to the teeth
which move in desired direction to correct the dental mal
The andresen activator was later modified by andresen
and Haupl in an attempt to optimize the the orthopedic
change that could be affected by these removable
appliances. the activator was constructed with a working
bite well beyond the resting length of the muscles to
ensure that forces be transferred to the jaws as well.
The compensatory contracture and myotactic reflex of
these muscles during function supplied mechanical
forces needed to redirecct the growth or remodelling
processes of the bones of the jaw.
The andresen activator was
further modified into a
vertically overextended splint
by Harvold, Woodside and
A construction bite was taken
in the direction of desired
correction. The bite was
opened 5 to 6 mm beyond the
The extreme stretch of the
muscles helped the appliances
to be in place even during
sleep. The appliances
produced a side effect of
dental intrusion. This ultimately
produced a autorotation of the
mandible and a relative class II
The design of this system
assumed that the viscoelastic
properties of the tissues under
this stress produced a
Petrovics growth studies however have come to show that increased condylar
cartilage growth is associated with a forward posturing of the mandible. The modus
operandi of functional appliances was explained as follows.
INCREASED CONTRACTILE ACTIVITY OF LPM
INCREASE IN GROWTH STIMULATING FACTORS
ENHANCEMENT OF LOCAL MEDIATORS
REDUCTION IN LOCAL REGULATORS
ADDITIONAL GROWTH OF THE CONDYLAR
ADDITIONAL SUBPERIOSTEAL OSSIFICATION
SUPPLEMENTARY LENGTHENING OF THE
Growth relativity hypothesis
The hypothesis was
put forth by John
Voudouris et al to
explain the modus
operandi of functional
appliances and the
cause for relapse.
LPM myectomy studies on animals by Whetten
and Johnston showed that there is little evidence
that LPM traction had any pronounced effect on
Dubner and Voudoris conducted permanently
implanted longitudinal muscle monitoring
techniques and observed that condylar growth
was associated with decreased postural and
functional activity of LPM.
Pancherz, Ingervall and Auf de Mauer observed
similar findings in humans.
Can mandibular growth be modified beyond it’s true
The answer seems to be elusive. As is shown by the use of the Milwakee braces.
However the Milwaukee braces phenomenon also shows us the remarkable rebound
capacity of the hard tissue system and the dominance of inherent growth potential
While Angle strongly believed that the mandible could be made to grow Case
disagreed. As Case states.. “Malrelations of this character point directly to heredity.
The claim and recently repeated inference that the mandible can be made to grow by
artificial stimuli beyond its inherent size is not in accord with any law of organic
development." Baring future chemical or genetic manipulation, this still appears to be
a valid principle, although there are others who strongly believe otherwise.
Case writes that "While the rapidity of their early growth may be hastened, while
inhibited developments may be stimulated to normal growth, and while the forms of
the bones may be varied slightly by bending, I doubt if it has ever been authentically
proved that natural or artificial forces have made them grow interstitially longer than
their inherent normal size.
Gianelly through various studies has sown that the mean growth modification
of 2mm can be achieved by functional appliance treatment. Thus when compared to a
6mm correction of class II relation to a class I the effects of functional appliances may
not be clinically significant.
Harvold found significantly higher increments in mandibular length during
treatment than after treatment. But however when he compared the results with
untreated controls matched for age and growth status he found that the changes can
only be ascribed to normal age related changes.
Studies by McNamara on the Frankl appliance and Herbst appliance effects
on the mandible and the dentition have shown both appliances had influenced the
growth of the craniofacial complex in treated persons. Significant skeletal changes
were noted in both treatment groups, with both groups showing an increase in
mandibular length and in lower facial height, as compared with controls.
McNamara and Bryan studied the Long-term
mandibular adaptations to protrusive function on 11
experimental animals.. At the end of the 144-week
experimental period, the mandibles of the treated animals
were 5 to 6 mm longer than those of the control animals.
They concluded that the results of this study do not
support the hypothesis that the mandible has a genetically
Different studies have shown varying results. This is due to the
varying landmarks used to analyze mandibular growth.
If one measures prognathism as related to a perpendicular to the
cranial base through sella most authors agree that pogonion moves
anteriorly more than normal with functional appliances. If the
condylar increment is measured as Cd-Pg diisatance the dispersion
of findings becomes more evident. This brings into question the role
of functional appliances in glenoid fossa remodelling.
The experiments on Rhesus maccaca monkeys by Woodside,
Metaxas and Altuna clearly suggest that a mandibular repositioning
can occur due to glenoid fossa changes and condylar growth with
the latter being more age dependent. They observed bone
apposition on the anterior surface of the post glenoid spine.
The search for good evidence for the use of functional appliances
may be difficult to find due to the methodology of current clinical
Limitations of current clinical and animal research:
A double blind study is not possible in testing functional appliances
and thus bias cannot be eliminated. The orthodontist is well aware of
the type of appliance he is using and it’s probable treatment effects it
can produce based on other studies and thus already has something
in mind to expect. And functional appliance unlike drugs are tested for
their treatment effects and not for their side effects. In cases of drugs
treatment effects are well proven in animal studies and can be
extrapolated to humans. Thus the patient as well as the orthodontist
undertake the study with a desired result in mind.
Growth versus treatment changes should always be compared with
untreated controls matched for age, sex and growth status. Even
though so much criteria may be taken the experimental samples and
control samples may not be totally matched because the growth
potential of two people may not be the same unless they are
monozygotic twins. And if monozygotic twins were even used it would
be unethical to treat one sibling while leaving the other untreated.
Some growth studies use class I individuals as controls while some
study's do not mention the nature of controls used. Studies by
McNamara, Bookstein, Baumrind and Righellis have used untreated
Class II as controls.
Though compliance may not be improved in animal research and and
histological changes can be studied, the animals used donot have any
growth defeciencies and treatment responses are those for normally
Most of the studies done by Petrovic and coworkers which substantiated
increased cell proliferation and increases in mandibular length with bite
jumping appliances were done on rats. Whether findings on other
mammalian mandibles can be extrapolated to humans is another
question which needs to be answered.
Can be defined as…” early orthodontic and
orthopedic intervention provided during the
mixed dentition and occasionally during the late
Advantages of early treatment:
The need for complicated surgical and orthodontic
procedures elimmintaed by early orthpedic
A abnormality is prevented from occurring – better
than wait to manifest itself in it’s fullest form
Orthodontists prefer to wait until the permanent teeth have erupted so a
more straight forward treatment plan can be done within a predictable
duration of time.
The question of remaining growth manifesting as relapse does not
Some malocclusions like skeletal class III due to prognathic mandible
are best treated after all skeletal growth is complete.
Patient co operation may be the biggest challenge in early treatment –
Patient burn out due to a long treatment duration may not help the
orthodontists cause during a second phase of fixed appliance treatment.
An extremely long duration of treatment may be a night mare for
Unreasonable treatment duration may lead to disillusionment of the
general population to orthodontic treatment.
General guidelines on timing of early treatment:
Treatment of class I tooth-size/arch-size discrepancy
to be initiated after the eruption of the four lower
incisors and the upper central incisors.
Treatment of class III is earlier than treatment of any
other malocclusion. It should be initiated with the loss
of upper deciduous incisors and while the permanent
upper incisors are erupting.
Class II malocclusions are best treated in the late
mixed dentition when the patient is in the
circumpubertal age. Studies petrovic, stutzmann and
Mcnamara have supported this concept.
Functional appliances and two phase treatment
Gregory king et al (2003) conducted a study based on PAR of
patients undergoing two phase treatment and single phase
treatment. Though at the end of treatment there was no significant
difference in the PAR of both groups, the two phase treatment group
showed significantly lesser PAR before beginning phase 2, which
may indicate that early treatment does influence PAR and may
provide social and psychological benefits to the patient.
Further a multicenter, randomized controlled trial of 174 children to
study the dental, skeletal and psychosocial effects of Twin Block
have shown that all changes produced were purely dento alveolar
and skeletal changes were actually so minimal as to be considered
clinically insignificant. However results did show that early Twin
Block use did result in an increase in self concept and a reduction
of negative social experiences.
Brackets are attachments on teeth placed to deliver the
appropriate forces and moments onto the teeth. Their designs
reflect the treatment concepts, philosophies and end of treatment
ideal the bracket designer had in mind when he designed the
appliance. With different philosophies developing over the years
different bracket designs too have entered the market for the
orthodontist to use.
brackets are of basically two types – ribbon arch brackets
and edgewise brackets. The ribbon arch brackets were first
designed by Angle for his Ribbon arch appliance. The bracket was
modified by inverting it by 180 degree and used by Raymond Begg
for his light arch wire appliance. Since then it has gone little
modification except by Brainerd Swain for his modern Begg
technique where a edgewise slot was combined with a vertical slot
to achieve better third order expression in stage IV.
Edgewise brackets though have undergone major changes
since it was first concieved by Angel. Angle used what is called
today as a single wing brackets. Later Twin brackets were designed
first by Swain. The bracket designed by Angle was a non
programmed bracket it was neither preangulated nor pretorqued.
The first preangulated bracket was designed by Ivan Lee and
Jarabak first designed Pretorqued and preangulated brackets. The
credit goes to Andrwes for designing the first fully programmed
brackets with first, second and third order values built into the
brackets to achieve his six keys of occlusion. Since then numerous
prescriptions with different tip and torque values have been
designed for various tretment philosophies.
controversies regarding bracket design include:
• the use of 0.018 slot or the 0.022 slot
0.018 slot or 0.022 slot ?
E.H. Angle was the first to design the Edgewise type
of bracket for his edgewise appliance.
He used the 0.022x0.028 slot for his appliance.
As the edgewise appliance originated before the
discovery of stainless steel, Angle was forced to use
gold alloy wires for making arch wires.
Gold alloy wires had a low modulus of elasticity and
therefore to increase the stiffness of the wire in
bending and torsion and to increase the rigidity Angle
had no other choice but to increase the dimensions of
the wire and therefore had to use the 0.022 slot.
0.018 slot or 0.022 slot ?
It was Steiner who first proposed the 0.018 slot (0.018 x 0.028)
and used it for the ‘Steiner’ brackets which were single width
brackets with rotation wings.
Swain later adopted the 0.018 slot for his Siamese brackets to
improve wire characteristics due to the decreased inter bracket
With the advent of stainless steel which is 50% stiffer than spring
tempered gold it became essential to decrease wire dimensions
to reduce force levels.
The 0.022 slot today prevails over the 0.018 slot because of the
development of newer orthodontic alloys such as TMA and NiTi.
It was the discovery of TMA with it’s stiffness characteristics
similar to gold that brought back the 0.022 slot back into the
0.018 slot or 0.022 slot ?
ADVANTAGES OF 0.018 SLOT
Decreased wire inventory
Decreased treatment time
Increased wire flexibity due to smaller dimension of
DISADVANTAGES OF 0.018 SLOT
Desired third order M/F ratios may not be
produced by newer orthodontic allloys.
0.018 slot or 0.022 slot ?
DISADVANTAGES OF 0.022 SLOT
Increased wire inventory
Inability to attain third order control untill last
stages of treatment
Increased treatment time.
ADVANTAGES OF 0.022 SLOT
Recommended for Orthognathic cases
Can use newer orthodontic alloys with minimum
0.018 slot or 0.022 slot ?
The world however seems to be divided over
the use of edgewise brackets.
The 0.022 slot is widely used in the United
States whereas the 0.018 (0.5mm) slot is
popular in Europe.
Are the 0.018 and 0.022 slots truly 0.018 and
Kusy and Whitley measured 24 brackets from
eight manufacturers microscopically to 0.0001
Three brackets were under sized whereas the
rest were oversized.
The largest 0.018 slot measured 0.0209
whereas the largest 0.022 slot measured
Are the 0.018 and 0.022 slots truly 0.018 and
Factors contributing to this variability….
Lack of verification standards
Varying manufacturer tolerances
United states versus European tooling
For example Europeans use metric tooling i.e mm, cm
, m. Their target value for machining a bracket which
would be 0.018 slot in the United states would be
0.5mm which is actually 0.0197 inches.
Are the 0.018 and 0.022 slots truly 0.018
and 0.022 …….?
Therefore even the most accurately machined
0.018 slot in europe would be oversized even
without manufacturer tolerance.
The 0.020 slot.
Rubin, peck and Kusy have proposed the use
of an 0.020 slot (0.5 mm)
This would reduce the burden on inventories
of users of both 0.018 and 0.022 slots and
reduce manufacturer costs.
THE RELEVANCE OF SLOT AND ARCH WIRE DIMENSIONS IN OUR
EVERY DAY PRACTICE:
Creekmore made a study on effective biomechanical torque
produced by brackets and wires of various manufacturers based on
the manufacturer tolerances supplied by them. His findings were as
• An .018 ´ .025 wire in an .022 slot has 15° of play. Thus if one
uses Andrew’s brackets with 7 torque on centrals, 3 on the lateral
and -7 on canine and premolars there would be absolutely no
torque expression because the play or deflection angle itself is
greater than the torque value of the brackets. if one uses a Roth
prescription with 17 on incisors and 10 on laterals the amount of
torque expressed would be 2 degree for the central and and 5
degree for the lateral.
•With an .019 ´ .025 wire in an .022 slot, there is 10½° of play. So
again, all of the torques mentioned are ineffective with an .019 ´ .
025 wire in an .022 slot.
•With an .0215 ´ .028 there would be 2° of play and thus at the
end of treatment even with a full slot wire we would be still 2
degree away from the desired value.
•.017 ´ .025 wire has 4.5° of play in an .018 slot, whereas an .018
square wire has only 3° of play. So, you would have better torque
control with an .018 square than an .017 ´ .025.
Though both the 0.018 and 0.022 slot may still be used based
on personal preferences, a uniform slot size and tooling units may be
necessary for standardization and to know that we really use the slot
size we wanted irrespective of where the manufacturer is based.
ESTHETIC NEED FOR
In countries where orthodontic treatment is widely
available many clinicians accept esthetic impairment as
sufficient cause for orthodontic treatment. Theratonale
underlying such recommendations appears to be based
oj the belief that impaired appearance usually results in
negative self esteem and poor social adjustment.
Others insist that orthodontic treatment should be
provided only when physical health or functioning is at
risk. They believe that a psychologically healthy
individual will adjust to his or her appearance and that
low only low self esteem triggers a negative self
ESTHETIC NEED FOR
The controversy is that whether we ru n the risk of
denying treatment and social and psychological well
being or whether we over treat our patients and force
upon society standards of appearance that are both
unrealistic and unattainable.
Studies by Dion have shown that the attractiveness of
physical appearance is an important determinant of how
much even very young children are liked by their peers.
Physically attractive individuals are percieved as
posssesing a great number of socially desirable traits
such as intelligence, friendliness, sensitivity and
Patzer through his research findings on physical
attractiveness has proposed that facial attractiveness is
possibly the most important determinant of physical beauty.
Furthermore more studies have shown that the mouth is
the most important component of facial attractiveness.
In a study conducted by Shaw photographs of children
were altered to show normal occlusion or malocclusion.
Both children and adults described faces with normal
occlusion as more attractive, more intelligent , less
aggressive, and more desirable as friends.
HELLER ET AL JUDGED APPRXIMATELY 33%OF YOUNG
Canadian adults born wth facial clefts to have marginally inadequate
psychological adjustment. In their study , pshycological functioning
did not appear to be related to objective assessmnet of the severity
of impairmrent but was strongly related with dissatisfaction with
Based on confidential interviews with 531 school children aged 9 to
13 years, Shaw et al found that teeth represesnted the fourth most
common target of teasing after height, weight and hair.
Based on occupational rankings by Hollinshead, Rutzen found that
treated subjects had achieved higher level of occupational status
than had non treated individuals, even though the group did not
differ in social a class or educational level.
the theoretical and emperical work on responses to facial
attractiveness leads us to at least one obvious generalization:
percieved facial attractiveness is a social asset whereas percieved
unattractiveness is a social liability.
the decisions about the need for treatment cannot be made
on objective assessment of functional or esthetic impairment alone.
The concept of esthetic need for treatment is best framed by
considering both the potential clinical improvement of facial
attractiveness and the individuals psychological and social
adjustment to perceptions of facial appearance. Thus the individuals
evaluations of the impact on their lives of dentofacial disfigurement
must play a key role in determining the actual need for treatment.
a patient who acknowledges his severe malocclusion may
not desire treatment despite the functional and esthetic problems
and may be a difficult patient to treat, while a patient with far less
severe impairment may be influenced by other social factors that
lead him to extremely negative self evaluation and a strong desire
CLASSIFICATION OF MALOCCLUSION
Malocclusion presents itself in numerous ways. Classification
involves the grouping together of various malocclusions into simpler or
smaller groups. In order to have a system of classification, standards
should be set that represent normalcy. The deviation from the accepted
norms should also be grouped into various smaller divisions.
The aim of every classification would be to help in diagnosis and
treatment planning and to categorize malocclusions into groups which
would ease communication between orthodontists.
Being dentistry’s first specialty orthodontics today does not
have a classification system which is universally accepted and followed –
a classification system which would clearly denote the malocclusion
present, aid in a treatment planning and indicate the severity of the
The classification system followed today is based on Angles
classification which was perceived by him almost 100 years ago based
on his treatment philosophies, ideals and paradigms of his time.
CLASSIFICATION OF MALOCCLUSION
What we today call normal occlusion was described as early as
the eighteenth century by John Hunter. Carabelli, in the midnineteenth century, was probably the first to describe in any
systematic way abnormal relationships of the upper and lower
dental arches. The terms edge-to-edge bite and overbite are
actually derived from Carabelli's system of classification
Many orthodontists have developed classification methods,
and among them are Kingsley, Angle, Case, Dewey, Anderson,
Hellman, Bennett, Simon, Ackerman and Proffit, and Elsasser.
Edward angle introduced a system of classifying
malocclusion in the year 1899. angles classification is still in use
after almost 100 years of it’s introduction due to it’s simplicity
Edward H. Angle contributed the concept that if the mesiobuccal
cusp of the maxillary first molar rests ill the buccal groove of the
mandibular first molar, and if the rest of the teeth in the arch are
aligned, ideal occlusion will result. (this is not the Class I as Angle
actually saw it) Angle described three basic types of what he
termed malocclusion, all of which represented deviations in an
An early criticism of the Angle system was that it merely described the
relationship of the teeth and did not include a diagnosis. Simon, Lundstrom,
Hellman, and most recently Horowitz and Hixon recognized the need to
differentiate dentoalveolar and skeletal discrepancies and to evaluate their
relative contributions toward the creation of a malocclusion. These authors
suggested that classification should include this type of diagnosis and point
logically to a treatment plan.
Another drawback in Angles classification is that it does not deal with
any malocclusion in it’s entirety. This gives rise to the issue of Analogous
and homologous malocclusions
Malocclusions having the same Angle classification may, indeed, be
only analogous malocclusions (having only the same occlusal relationships)
and not necessarily homologous (having all characteristics in common
Homologous malocclusions require similar treatment plans, whereas
analogous malocclusions may require different treatment approaches
thereby clearly highlighting a great draawback of Angles classification.
Since Angle and his followers did not recognize any need for the
extraction of teeth, the Angle system does not take into account the
possibility of arch-length problems. The reintroduction of extraction into
orthodontic therapy has made it necessary for orthodontists to add archlength analysis as an additional step in classification.
Angle acknowledged that the first molar might erupt in an altered
position when influenced by the malpositions of other teeth or the loss or
non development of deciduous and permanent teeth anterior to the first
molar. Therefore Angle recommended visualizing the upper first molar into
its proper position relative to the jugal buttress before classifying the
malocclusion. There are two problems with this concept. First, visualizing
the "correct" position of the upper first molar to the jugal buttress and lining
up the remaining dental units relative to it is a very subjective pursuit. It is
quite probable that no two orthodontists would exactly visualize the same
"correct" position. And second, modern orthodontists are more concerned
with the proper position of the incisors relative to the profile for esthetic and
stability concerns and are willing to adjust first molar position and even
sacrifice teeth to better align the incisors (concepts Angle would never have
accepted). Modern orthodontists advance molars in extraction treatments or
distalize molars in nonextraction treatments with little concern for the
immutable relationship of the upper first molar to the bony landmarks, such
as the key ridge, as promulgated by Angle.
A final, but not inconsequential, difficulty with Angle's classification procedure
is that the classification does not indicate the complexity of the problem.
The drawbacks of Angles
classiication are made worse
by the way most
interpreted his classification
Every dental student learns
the Angle "mesiobuccal cusp
of the upper first molar fits
into the buccal groove of the
lower first molar“
Angle described in minute detail each contacting cusp incline
to prove his point that in ideal occlusion every tooth (except the
lower centrals and upper third molars) should have two antagonists.
In other words, even if a patient has the mesiobuccal cusp of the
upper first molar fitting perfectly into the lower molar buccal groove
the patient does not possess proper occlusion according to Angle,,
unless the upper first molar also has a mesial crown tilt that allows
the distal incline of the distal cusp of the upper first molar to occlude
with the mesial incline of the mesial cusp of the lower second molar.
Proper cuspal incline contacts of all teeth should be
noted. Angle emphasized the importance of each premolar and
canine contacting two occluding teeth. An occlusion where the
first molars classically fit the criteria of the upper mesiobuccal
cusp to lower molar groove, but the premolars and canine
contact only one opponent tooth each, would be considered
Class I by Angle (because Class I is a premolar-width range of
abnormality). However, Angle would not have considered the
occlusion as having met his standards for "ideal" occlusion of a
well-treated case. Therefore all "ideal" occlusions are Class I,
but not all Class I occlusions are "ideal."
The original classification by Angle, had Class II as a full premolarwidth distoclusion and Class III as a full premolar-width
mesioclusion. Assuming an average premolar width of 7.5 mm, then
Class I ranged from 7 mm mesioclusion to 7 mm distoclusion, for a
total range of Class I of 14 mm. This range was far too broad, and
so in 1907, Angle revised his definition, making Class II more than
half of a cusp distoclusion and Class III more than half of a cusp
mesioclusion. Angle's modification reduced the range from 14 mm
to a 7 mm range. However, 7 mm is still too broad a range to act as
a treatment goal if an orthodontist is to treat with precision.
Dewey later modified angle’s classification. He divided angles class I into
five types and angles class III into three types
Class I modifications:
Tpe 1: class I malocclusion with crowded anterior teeth
Type: class I with protrusive maxillary incisors.
Type 3: class I malocclusion with anterior cross bite
Type 4: class I molar relation with posterior cross bite.
Type 5: permanent molar has mesially drifted mesially due to
premature extraction of deciduous molars.
Class iii modifications:
The upper and lower dental arches when viwed separately are well
aligned but when occluded have a dedge to edge incisal relationship
The mandibular incisors are crowded and are in lingual relationto
the maxillary incisors
The maxillary incisors are crowded and are in cross bite to the
In 1912, in a report to the British Society for the Study of Orthodontics,
Norman Bennett4 suggested that malocclusions be classified with regard to
deviations in the transverse dimension, the sagittal dimension, and the
vertical dimension. This recommendation, rejected at the time, was later
realized in the work of Simon and the development of his system of
gnathostatics. Simon related the teeth to the rest of the face and cranium in
all three dimensions of space.
Historically, Simon attempted a canine-focused classification. His Law of the
Canine considered the orbital plane (a line drawn from orbitale
perpendicular to Frankfort horizontal) as coincident with the distal third of
the maxillary canine in ideal occlusion. While modern orthodontists no
longer consider Simon's law valid, the strategic position occupied by the
canine makes it a favored tooth to reference for classification.
Canine relation classification:
Classification was based on the sagittal relation of the
maxillary canine to the mandibular canine.
Maxillary canines are among the most stable of dental
units because they are the longest rooted of all teeth
and therefore very well anchored to the alveolar bone.
The canine is the "keystone" tooth in the dental arch,
and like the keystone of a stone archway, it provides
a buttressing support for the incisors, as well as the
posterior teeth. Also, canines provide a vital protective
function in lateral excursive movements.
However, the principal objection to a canine-derived classification
relates to tooth anatomy. The maxillary canine exhibits a mesial
incisal ridge that is shorter and less severely sloped than its distal
incisal ridge. As a result, the central axis of the maxillary canine
does not bisect the cusp tip. Tooth sizes and shapes vary, but the
cusp tip averages 1 to 1.5 mm mesial to the center axis. Therefore
the cusp tip of the maxillary canine does not directly fit into the
embrasure formed by the mandibular canine and the first premolar,
but rides up on the distal slope of the mandibular canine . Also, the
cusp tip of the maxillary canine does not work well as a landmark
because occlusal wear frequently alters the cusp tip from a point to
a flat facet, and the modified architecture of its incisal edge
obscures the true cuspal form. Although not ideal, one could use the
imaginary center axis of the maxillary canine as a reference point,
since it lines up with the mandibular canine-first premolar
The maxillary canine is one of the last teeth to
erupt (other than third molars). This holds up
classification efforts until the patient is 12 years,
or older in slowly erupting patients. The
deciduous canine offers little assistance with
classification since it is smaller in mesiodistal
width than its permanent successor, resulting in
a center axis that is not coincident with the
center axis of its future permanent replacement.
The premolar classification was put forth by Morton Katz as a
modification to the Angle’s classification
premolars usually present a sharply defined cusp tip, which is
centered on the central axis of the premolar crown and which fits
precisely into the opposing embrasure. Also, the cuspal inclines are
steeper and deeper than molar cusps, which makes a more positive
From the negative perspective, orthodontists traditionally have not
had high regard for premolars as functional dental units and have
selected premolars most often of all tooth types for sacrifice in an
extraction treatment. Also, premolars may have anomalous tooth
size or shape. Furthermore, some judgment is required when less
than a full complement of premolars are present
A premolar-derived classification
Class I :The most anterior upper
premolar fits exactly into the
embrasure created by the distal
contact of the most anterior lower
In the rare instance where no premolar exists in a quadrant, then the center axis of the upper
canine crown (not the cusp tip) should be used as a reference to the distal contact of the
Deciduous and mixed dentition
the center axis of the upper
first deciduous molar should
split the embrasure between
both lower deciduous molars
However, in the event that an
upper first deciduous molar is
prematurely lost, a line drawn
through the center axis of the
edentulous space should
bisect the embrasure between
the two lower deciduous
Quantifying the classification
This proposed modified
occlusion (as described by
Angle) as zero (0). A plus
sign (+) designates Class II
direction and a minus sign
(– ) designates Class III
tendency. In this article the
right side is evaluated first,
then the left side. Ideal
occlusion on both right and
left sides is, therefore, (0,0).
Quantifying the classification
For example, if a patient
presents with ideal
intermeshing on the right side,
but a 2 mm Class II tendency
on the left side, then the
modified classification would
A third patient who is 1.5 mm
Class II on the right and 3.5
mm Class III on the left side
would be classified (+1.5,-3.5)
From the above discussion it is clear that the system of
classification we use today is inadequate in describing a dental
anomaly in it’s entirety, aid in treatment planning or be easy to
use. A universal classification system will be necessary which will
be accepted by all orthodontists around the world. This would help
us in standardizing malocclusion rather than disagreeing on the
very nature of problem the patient has.
THE USE OF RIGID INTERNAL FIXATION
The most universally used method for stabilisation of
ractures and osteotomies ha been the use of
intermaxillary fixation (IMF).
Common methods of IMF include the use of arch bars
, Ivy loops, cast splints or simply the use of the
The introduction of rigid fixation has reduced the time
required forIMF which would otherwise be 3 to 8
weeks of immobilisation.
THE USE OF RIGID INTERNAL
Controversies in the use of Rigid internal
Does RIF improve bony healing and post operative
Does it improve long term stability?
Is there a greater chance of developing TMD post
operatively with RIF?
THE USE OF RIGID INTERNAL
It was Spiessl who first described the use
of bone screws for fixation of a sagittal
osteotomy in 1974.
The various RIF systems include:
Advantages of rigid fixation:
Reduction or elimination of IMF
Period of IMF can vary from 2to three weeks or the
suregon may choose not to use IMF at all.
Increased post operative safety
More rapid bone healing
Ability to check the post operative occlusion in cases
where segments have been displaced.
Ability to stabilize osteotomies that would otherwise
be difficult to stabilise
Better control of bony segments
Advantages of rigid fixation:
More rapid reduction of oedema
Improved condition of the TMJ and muscles of mastication post
Increased risk of infection
Need for plate and screw removal
TMJ considerations in
the use of RIF
Kundert compared condylar displacement in patients
treated with sagittal osteotomies of the mandible with
screw fixation and wire fixation. The authors noted
condylar disraction in both groups with the magnitude
slightly greater in the screw fixation group.
A computed tomography study showed some medial
rotation of the codylar segment. Varying inter condylar
distances were also seen.
Timmis et al compared 28 patients with rigid fixation 14
patients treated with wire fixation . The wire
osteosynthesis group showed no statistical change in
facial pain, TMJ pain or clinical signs after surgery. The
rigid fixation group however showed significant decrease
in TMJ noise, facial pain, and TMJ pain.
Carter et al studied the effects of various fixation methods for mandibular
advancement surgery, they concluded that:
After sagittal split osteotomies of the mandibular rami, horizontal rotation of the
condyle usually occurs, regardless of the type of fixation or the position of the
2. There were statistically significant changes (p < 0.001) in the intercondylar
angles with all three types of fixation when the distal segments were measured in
the anterior and posterior positions. However, the clinical significance of these
changes was not proved.
3. In the three methods of fixation, the only statistically significant difference (p =
0.005) was between screw and wire osteosynthesis when the distal segments
were in the forward position.
4. There were no consistent differences in horizontal rotation between the
condyles that were fixed first and those that were fixed second, for either the left
or right side.
5. The size of the original intercondylar angle did not affect the magnitude of
change in the postoperative intercondylar angle, regardless of the position of the
distal segment or the type of fixation used.
RETENTION AND RELAPSE
For many years clinicians did not agree about the need for retention.
Different philosophies or schools of thought have developed and
present day concepts generally combine several of these theories.
The occlusion School: Kingsley stated that, “ The occlusion of the
teeth is the most potent factor in determining the stability in a new
position”. Proper occlusion is of primary importance in retention.
The apical Base school: It was Axel Lundstrom who suggested that
the apical base was an important factor in maintaining correct
The mandibular incisor school: Grieve and Tweed suggested that
the mandibular incisor must be kept upright over the basal bone.
The musculature school: Rogers emphasised the need for
establishing proper muscle balance for maintanence of occlusion.
RETENTION AND RELAPSE
Relapse in lower anterior region: Many hypotheses have been put
forward to explain the incidence of lower incisor crowding after
Relationship of third molars : the mesial eruptive force of the third
molars give rise to lower anterior crowding. This led to therapeutic
extractions and removal of impacted third molars. Ades et al compared
four groups of patients 10 years out of retention. The groups includedthird molars erupted, third molar agenesis, third molar impaction, and
third molar extraction cases. He found no difference in the mandibular
incisor crowding, inter canine width between these groups.
Mesial component of force and physiological mesial migration.
Late mandibular growth and maximum intercanine width: continued
mandibular growth even after maturation of inter canine width can lead
to incisor crowding. A retention protocol untill completion of skeletal
growth may be necessary in boys.
RETENTION AND RELAPSE
Arguments against the apical base school and the mandibular
Growth may play a major role in determing the apical base relationship
to each other and the relation ship of the teeth to their apical bases.
Patients treated in the growing age will be treated to axial inclination for
their respective ANB angle or to an upright incisor position.
Continued mandibular growt will lead to a decrease in FMA,ANB angles
and flattening of the occ;usal plane. These changes lead to a more
upright incisor positioning and a natural endency for the mandibular
dentition to becoe more recessive in rekation to the skeletal base.
Thus further growth of the patient may play an important role in deciding
the retention prorocol.
RETENTION AND RELAPSE
Arguments against the occlusion and
Achieving post treatment stability by
equilibration, elimination of cross arch
deflective contacts may not be enough.
Factors other than functional overload can
lead to post treatment changes.
The use of post treatment equilibration
procedures to improve stabilit is debatable.
RETENTION AND RELAPSE
Duration of retention:
At the moment there is no agreement as to a
specific duration of retention for patients.
There is no clinical evidence as to whether a
longer duration of retention ha s better post
treatment stability than one of shorter
orthodontics may be the only speciality which has
“pholosophies”. It was based on these philosophies that most
work in Orthodontics was done. However treatment
philosophies may not be enough in todays world. We need
more scientific basis to back our treatment protocols. We
need to follow ‘evidence based Orthodontics’ more than
‘opinion based orthodontics’. The only way this can be done
is to improve our clinical research.
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