Decision in Class II Subdivision Malocclusions Treatment:
CASE REPORT
Three Case Reports with Contrasting Strategies
1Ashish Kamboj, 2Apoorva Sharma, 3Pulkit Lakhani, 4SS Chopra
To cite: Ashish Kamboj,
Apoorva Sharma, Pulkit
1-3Asst. Prof, 4Professor
Lakhani, SS Chopra
1Dept. of dental surgery, Armed Forces Medical College, Pune
Decision in Class II
2Dept. of Orthodontics, Rajasthan Dental College,Jaipur
Subdivision Malocclusions
Treatment: Three Case
3Dept. of Orthodontics, Surendra Dental College,Sriganganagar
Reports with Contrasting
Strategies
4Dept. of dental surgery, Armed Forces Medical College, Pune
J Contemp Orthod 2020;4(4):
ABSTRACT
6-10.
Abstract: Class II Subdivision refers to the asymmetric molar relationship that can be commonly
accounted to dental and occasionally to the skeletal disharmony. Furthermore, the discrepancy
Received on:
may be present in the maxilla or the mandible. To put it differently Class II subdivision is a
25-11-2020
heterogeneous group of malocclusions and cannot be considered as a discrete entity to be
Accepted on:
treated with predefined specific strategies.
15-12-2020
Source of Support: Nil
Treatment goals encompass the usual cook-book approach and entail the orthodontists to think-
Conflict of Interest: None
before-act strategy considering all the parameters that may be affected favorably or deleteriously
while executing a specific plan. Treatment options may vary from non-extraction to four premolar
extractions depending upon the site and severity of the malocclusion.
Another consideration would be the indispensable side-effects of the biomechanics involved that
may be symmetric or asymmetric, again depending upon the needs of the patient. These not
only require thorough diagnosis but also clarity in the treatment goals.
This piece of literature would briefly outline the important considerations while treating Class II
Subdivision cases with the help of examples of three patients bearing different etiologies treated
with contrasting strategies.
Keywords: Class-II Subdiv malocclusion, Midface deficiency, Decompensation, Overjet, Crossbite
maxillary dental midline with the facial midline and deviation of
INTRODUCTION
the mandibular midline toward the Class II side. It is created by
Class II Subdivision may be defined as the one with Class II
the distal positioning of the mandibular first molar on the class II
molar relationship only on one side of the dentition. Class II
side. Frequency of occurrence is 61.36%.Type 2 characterizes
Subdivision malocclusions have characteristics of both Class I
deviated maxillary dental midline away from the Class II side
and Class II. Class II Subdivisions feature distal molar
and coincident mandibular midline with the facial midline.It is
occlusion on one side and Class I molar occlusion on the
created by mesial positioning of maxillary molar on class II side.
contra-lateral side. The disagreement in molar relationships
Frequency of occurrence is 20%. Combination type involves
between each side results in asymmetric occlusal relationship
deviation of the maxillary and mandibular dental midlines from
and midlines. For clarity, the term subdivision refers to the
the facial midline in opposite directionswith the frequency of
Class II side.
occurrence of about 20%.2
Class II subdivisions are estimated to account for upto 50% of
Factors like early loss of a primary second molar on one side
all Class II malocclusions and are among the most common
with unilateral loss of leeway space, premature exfoliation of
dental asymmetries in the orthodontic population.1Class II
primary canines,ankylosed primary molars,ectopic eruption of
Subdivision
malocclusions
can
involve
skeletal
maxillary
first
molars,
congenitally
missing teeth,
asymmetries,dentoalveolar asymmetries, functional shift due
supernumerary teeth, caries with loss of interproximal tooth
to occlusal interferences ortemporomandibular joint disorders
structure,tooth size discrepancy, excess spacing, asymmetric
(disk displacement & pathology).
crowding are important in aetiology of subdivision
Janson et al,2 evaluated three types of Class II Subdivision
malocclusions.
malocclusion and defined Type 1 as the one with coinciding
The source of the subdivision must be determined to know if the
6
asymmetry is skeletal, dental, or possibly a combination of
current appliances in correcting the molar relationship can be
both; maxillary arch, mandibular arch or both. If it is dental
offset to a great extent by altering the timing of extraction.3,5
related, then orthodontics alone should suffice.Even after
CLASS II SUBDIVISION TYPE 2 CASES
correct diagnosis, treatment can be difficult because it often
Class II subdivision Type 2 cases can be treated either with
involves asymmetric extractions and asymmetric mechanics.It
single premolar extraction plan on Class II side ornon-extraction
is imperative to ascertain whether a dental midline deviation
plan by distalization of the molar on the Class II side.Extraction
is due to buccal segment asymmetry or whether it is primarily
plan will correct maxillary midline deviation, the Class II molar
due to uneven crowding in the arches.3
can remain in Class II while the canines and contra-lateral molar
It is now imperative to state that subdivision involves a wide
will finish in a Class I relationship.Distalization will correct
array of malocclusion that may involve a simple unilateral
midline deviation as well as molar relation.
buccal segment asymmetry,dental in origin to a more severe
CLASS II SUBDIVISION COMBINATION TYPE
complete arch skewing that may be skeletal in origin. Thus,
CASES
the spectrum of subdivision would involve an incessant
combination of vast aetiological aspects that may individually
As the name suggests, it is the combination of above two and
or in combination with other contributing factors complicate
may require a more planned approach when treating such
the diagnosis and treatment strategies applicable in each
subjects. The treatment plan would vary with the etiology and
patient. The asymmetries of skeletal origin may be more
severity of discrepancy.
critical and might demand an extensive surgical intervention.
In view of specificity in the application of the abovementioned
Nevertheless, the non-surgical approaches reprimand a
guidelines it is imperative to reinforce the understanding of the
thorough understanding of these malocclusions in order to
readers with appropriate examples. Three Class II subdivision
reach to an appropriate diagnosis that would lead to the most
patients treated in a dental centre in Pune (Maharashtra) India
pertinent and validate treatment decisions.
will be discussed to give clarity to the subject. Table-1 compares
One of the simplest, yet robust in majority of cases is the
the pre-treatment and post-treatment cephalometric values of
description of subdivision malocclusion by Jansonet al2, that
the three cases.
grossly divides the same into three subtypes, as described
CASE-1:CLASS II SUBDIVISION RIGHT TYPE
earlier. It is quite essential to review these before detailing the
1 CASE
diagnosis, treatment planning and outcome of the cases
Treatment by: Asymmetric 3 premolar Extractions
representing the each prototype.
A 20 years old post pubertal female with Class I jaw bases and
CLASS II SUBDIVISION TYPE 1 CASES
average growth pattern reported to the orthodontic opd with
If the profile of patient dictates for extractions, they can be
prominent features of convex profile, incompetent lips, acute
either symmetric
(4 premolar extraction) or differential
nasolabial angle, grossly symmetrical face,compromised
(asymmetric-3 premolar extraction). Pleasing profile on the
periodontal health and increased incisor show. Her upper dental
other hand contra-indicates extractions. Non extraction
midline was coincident with the facial midline and lower dental
treatment plan includes Class II elastics, diagonal elastics,
midline was deviated towards right side by 2mm.
asymmetric elastics (Class II on malocclusion side and Class
III on normal side) or spring corrector.
Clinical examination ascertained that the malocclusion was
dental in origin as indicated by the absence of gross asymmetry
The three bicuspid extraction method shows slightly better
in the extra-oral facial photographs (Fig.1). Furthermore, there
treatment success rate in correcting the midline deviation and
was tipping of the lower incisors on the right side that could be
a tendency for better correction of antero-posterior
clearly appreciated on the orthopantomogram of the patient
discrepancy of posterior segments, compared with four
(Fig.1). It was now clear that there was no underlying skeletal
premolar extraction plan.4
asymmetry which was also reinforced by the history of
DEFERRED EXTRACTION OPTION
premature exfoliation of deciduous molar due to caries on lower
left side resulting in the presence of asymmetric lower molar
In many Class II subdivision cases, it is worthwhile to delay
positions with mandibular left molar occupying more mesial
the extraction of a mandibular premolar in the affected
position in the arch as seen in the intra-oral mandibular occlusal
quadrant
(Class II side) until a good canine interlocking
photograph leading to Class I molar relationship on the left side
(Class I) relationship is obtained.This delay will concurrently
and Class II molar relationship on the right side and subsequent
correct compensatory mesiodistal inclination of anterior teeth
lower dental midline shift towards right side.
as well as midlines.The inherent mechanical limitations of
7
Journal of Contemporary Orthodontics, Oct-Dec 2020;4(4):6-10
Ashish Kamboj et al
Treatment strategy included periodontal maintenance,
with prominent features of convex profile, incompetent lips,
correction of exhibited malocclusion using comprehensive
acute nasolabial angle, grossly symmetrical face, increased
fixed orthodontic mechanotherapy with PEA
(M.B.T.
incisor show, deviated upper midline to the right side by
prescription
0.022-inch slot) with extraction treatment
3mmand lip sucking habit.
approach with asymmetric extractions
(14,24,34). Upper
Clinical examination could ascertain that the malocclusion was
extraction spaces were utilized to correct inclinations of upper
notpurelydental in origin despite the absence of gross asymmetry
anterior teeth.It was decided to extract lower left first
in the extra-oral facial photographs. There was bodily shift of
premolar to correct deviated midline to allow tooth movement
upper incisors towards the right side that could be clearly
to that side and to correct dental inclinations. The purpose of
appreciated on the orthopantomogram of the patient
(Fig.2)
asymmetric extraction was to obtain Class I canine
indicating skeletal origin due to skewing of arches and/or basal
relationship on both sides, Class I molar relationship on left
bone. There was also the presence of asymmetric upper molar
side and Class II molar relationship on right side with ideal
positions with maxillary left molar occupying more mesial
overjet and overbite.
position in the arch as seen in the intra-oral maxillaryocclusal
TREATMENT PROGRESS AND RESULTS
photograph
(Fig.2) with no history of caries or premature
exfoliation of deciduous teeth.
Treatment strategy includedcorrection of exhibited malocclusion
using comprehensive fixed orthodontic mechanotherapy with
PEA(M.B.T. prescription
0.022-inchslot) with non-extraction
treatment approach with correction of Class II molar relationship
on left side by unilateral distalization using Jones Jig,
interception of lip sucking habit and increasing the arch
perimeter in the lower dental arch for correction of crowdingby
using lip bumper.
TREATMENT PROGRESS AND RESULTS
An active treatment period of 19 months was utilized to
relieve the malocclusion that involved sliding mechanics for
initial canine retraction followed by enmasse incisor retraction
in the upper arch by the use of bilateral Class I force. In the
lower arch, unilateral Class I force was used on the left side to
sequentially retract canine followed by complete space
consolidation on the same side. The asymmetric mechanics
were supplemented with Class II elastic force to reinforce the
upper anchorage while maintaining the molar relationships on
the respective sides.
Post treatmentfeatures included improved soft tissue facial
esthetics, improved lip competency,dental midlines coincident
An active treatment period of 14 months was utilized to relieve
with the facial midline, improved nasolabial angle and
the malocclusion that involved unilateral distalization using
improved periodontal health of lower anteriors.
Jones Jig that was completed in
4.5 months followed by
CASE 2: CLASS II SUBDIVISION LEFT
correction of upper dental midline and inclination of upper
incisors by sliding mechanics with the use of unilateral Class I
TYPE 2 CASE
force on the left side.Habit interception using lip bumper was
Treatment:Non Extraction by Molar Distalizationonthe Left
discontinued after 8 months. The asymmetric mechanics were
Side.
supplemented with asymmetric Class II elastic force to reinforce
the upper anchorage while maintaining the molar relationships
A 13 years old circum-pubertal female with Class I jaw bases
on the respective sides.
and horizontal growth pattern reported to the orthodontic opd
8
Post
treatmentfeatures
included
improved
lip
mechanotherapy with PEA (M.B.T. prescription 0.022-inch slot)
competency,upper midline coincident with the facial midline,
with extraction treatment approach with symmetric extractions
lower lip trap resolved andnasolabial angle improved.
(14,24,34,44). Upper extraction spaces were utilized to correct
TABLE-1
Variable
CASE 1
CASE 2
CASE 3
(Type 1)
(Type 2)
(Combination Type)
Pre
Post
Pre
Post
Pre
Post treatment
treatment
treatment
treatment
treatment
treatment
SNA
860
870
780
780
790
800
SNB
820
820
740
740
760
770
ANB
40
50
40
40
30
30
U1-NA
430/13mm
140/3mm
400/12mm
200/5mm
260/7mm
210/3mm
U1-SN
1280
820
1170
1000
950
910
U1-PP
1360
101.50
1310
1140
1190
1110
LI-NB
400/12mm
350/7mm
170/4mm
360/8mm
280/6mm
230/4mm
IMPA
990
940
890
980
950
910
Interincisal
940
1270
1190
1250
1220
1310
Angle
FMA
260
280
240
260
250
250
SN-GoGn
340
350
300
330
300
300
Overjet
7mm
2mm
11mm
2mm
6mm
2mm
Nasolabial
900
1010
800
1030
990
1060
Angle
crowding, midline and inclinations of upper anterior teeth. It was
CASE 3: CLASS II SUBDIVISION LEFT
decided to extract lower first premolars to correct deviated
COMBINATION TYPE
midline and to correct dental inclinations. The purpose of
symmetric extraction was to obtain Class I canines and molar
Treatment by: Symmetric 4 Premolar Extractions
relationship on both sides with ideal overjet and overbite.
TREATMENT PROGRESS AND RESULTS
A 16 years old post-pubertal female patient with Class I jaw
bases and average growth pattern reported to the orthodontic
opd with prominent features of convex profile, incompetent
lips, acute nasolabial angle, grossly asymmetrical face
showing deviation towards right, upper dental midline
deviated towards right by 4mm and lower towards left by
3mm with respect to facial midline.
Clinical examination could ascertain that the malocclusion
was not purely dental and/or skeletal in origin despite the
presence of gross asymmetry in the extra-oral facial
photographs. There was bodily shift of upper incisors towards
the right side that could be clearly appreciated on the
orthopantomogram of the patient (Fig.3). There was also the
An
presence of asymmetric upper and lowermolar positions with
active treatment period of 22 months was utilized to relieve the
both upper and lower left molars occupying more mesial
malocclusion that involved sliding mechanics for the correction
position in the arch along with asymmetric anterior crowding
of anterior crowding initially, followed by en masse anterior
as seen in the intra-oral maxillary occlusal photograph(Fig.3).
retraction in both upper and lower arches by the use of bilateral
Class I force. The asymmetric mechanics were chosen for this
Treatment strategy included correction of exhibited
particular case to titrate space closure with critical anchorage in
malocclusion using comprehensive fixed orthodontic
9
Journal of Contemporary Orthodontics, Oct-Dec 2020;4(4):6-10
Ashish Kamboj et al
the upper arch by the use of nance palatal button and by the
CONCLUSION
consolidation of the buccal segment in the lower right
Patients with Class II Subdivision malocclusions although seen
quadrant, and intermediate anchorage in the lower left
commonly, have long been a treatment challenge for clinicians.
quadrant supplemented with asymmetric Class II elastic force
Treating asymmetric malocclusions is inherently more difficult
only on the left side to allow for the slippage of molar and
than treating symmetric malocclusions, as symmetry in one or
obtain bilateral Class I molar relationship with ideal overjet
both arches needs to be re-established, usually with asymmetric
and overbite.
extractions, mechanics, or surgery. For example, Class II
subdivisions that are due to maxillary dental asymmetries might
Post treatmentfeatures included improved lip competency,
be addressed with asymmetric extractions. Similarly, Class II
well aligned arches andacceptable nasolabial angle.
subdivisions due to mandibular skeletal asymmetry might be
DISCUSSION
ideally
corrected
with
asymmetric
mandibular
advancements.Whatsoever may be the etiology, treatment goals
Class II subdivision is a heterogeneous group of
encompass the usual cook-book approach and entail the
malocclusions and cannot be considered as a discrete entity to
orthodontists to think-before-act strategy considering all the
be treated with predefined specific strategies. The discrepancy
parameters that may be affected favorably or deleteriously while
may be present in the maxilla, mandible or in both the arches.
executing a specific plan.It is indubitable to conclude from the
Alaviet al6 and Rose et al7 observed that Class II subdivisions
aforementioned cases that if the underlying etiology has been
result mainly from asymmetry of the mandibular first molars,
correctly identified and appropriate diagnosis is made, ideal
by distal positioning of the mandibular molars on the Class II
results can be achieved with minimal side effects keeping
side. Jansonet al2concluded that asymmetric antero-posterior
reasonable objectives in mind by employing predictable
relationships in Class II Subdivision malocclusion were
mechanics.
mainly dentoalveolar. Class II Subdivision malocclusion does
REFERENCES
not present skeletal asymmetries in relation to normal
1.
Azevedo ARP, Janson G, Henriques JFC, de Freitas MR.
occlusion. Azevadoet al1 concluded that subdivision was
Evaluation of asymmetries between subjects with Class II
primarily dentoalveolar with minimum skeletal involvement.
subdivision and apparent facial asymmetry and those with
According to Sanders et al8, the components contributing to
normal occlusion. Am J OrthodDentofacialOrthop
an asymmetric antero-posterior relationship in a Class II
2006;129(3):376-83.
Subdivision malocclusion are multifactorial.According to
2.
Janson GR, Metaxas A, Woodside DG, deFreitas MR, Pinzan
them, the etiology of Class II Subdivision malocclusion is
A. Three dimensional evaluation of skeletal and dental
primarily due to an asymmetric mandible that is shorter and
asymmetries in class II subdivision malocclusion. Am J
positioned posteriorly on the Class II side. Also mesial
OrthodDentofacialOrthop 2001;119(4):406-18.
positioning of the maxillary first molar on the Class II side
3.
Turpin DL. Correcting the class II subdivision
without skeletal asymmetry was the second contributing
malocclusion.Am J OrthodDentofacialOrthop
2005;
factor and distal positioning of the mandibular first molar on
128(5):555-6.
the Class II side was the third contributing factor.
4.
Janson G, Dainesi EA, Henriques JF, de Freitas MR, de Lima
Most of the orthodontic treatment strategies were originally
KJ. Class II subdivision treatment success rate with
grounded on the imperialistic approach of the ones who
symmetric and asymmetric extraction protocols. Am J
developed them. Yet the better understanding of the various
OrthodDentofacialOrthop 2003; 124(3):257-64.
clinical situations have provoked the new era of Evidence-
5.
Mailankody J. Deferred extraction option for Class II
based orthodontics. This not only marks the clarity in the
subdivision malocclusion. Am J OrthodDentofacialOrthop
vision of the orthodontists in terms of diagnosis but also the
2006;129(4):455.
definitive protocols in varying spectrum of malocclusions.
6.
Alavi DG, BeGole EA, Schneider BJ. Facial and dental
asymmetries in Class II subdivision malocclusion. Am J
Class II subdivision has always been a source of dilemma due
OrthodDentofacialOrthop 1988;93(1):38-46.
to heterogeneity of the subgroups that it covers and only the
7.
Rose JM, Sadowsky C, BeGole EA, Moles R. Am J
clear understanding of each subtype would lead to the
OrthodDentofacialOrthop 1994;105(5):489-95.
successful treatment. Various types as instituted by Jansonet
8.
Sanders DA, Rigali PH, Neace WP, Uribe F, Nanda R.
al2have described with their treatment optionsto provide a
Skeletal and dental asymmetries in Class II subdivision
more practical approach to deal with these efficiently.
malocclusions using cone-beam computed tomography. Am J
OrthodDentofacialOrthop 2010;138(5):542.e1-20.
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