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Treatment of a pseudo Class III relationship in the mixed dentition:
A case report
Sahar F. AlBarakati,
BDS, MSc
Department of Preventive Dental Sciences, College of Dentistry, King Saud University
This
article describes a case report in which a Class III patient was successfully
treated with an inverted labial bow appliance.
The appliance is easy to make, efficient and well tolerated by the
patient. Early treatment of Class III conditions is recommended. The importance of differentiating between
true Class III and pseudo Class III malocclusions is emphasized.
Introduction and Literature Review
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Clinicians
are continually confronted with Class III malocclusion during permanent and
mixed dentition phases.1-5 The proper time to treat a Class III malocclusion has
been a subject of controversy.5-7 The question is whether or not
interceptive therapy should be contemplated during the primary dentition stage
or should it be deferred until the mixed dentition when the permanent first
molars and several permanent teeth have erupted or after the growth period has
ended. Optimal timing for treatment has been addressed by many authors directly
or indirectly.2-7
When dealing with Class III malocclusion, confusion may arise as
three types of malocclusions can have the same appearance1,8 true
skeletal Class III malocclusion, the simple anterior crossbite, and the pseudo
Class III malocclusion. Each has a distinct etiology which serves to
differentiate them. In a true Class III malocclusion as described by Angle,9
the lower first molar is mesially positioned relative to the upper first molar.
This relationship may result from a skeletal discrepancy which is characterized
by mandibular protrusion and a normal maxilla, or maxillary retrusion and a
normal mandible, or a combination of maxillary retrusion and mandibular
protrusion.8,10 The dental components are usually characterized with
proclined maxillary incisors and retroclined mandibular incisors to achieve
dentoalveolar compensation.8,10 In
the second type of Class III malocclusion, a simple anterior crossbite is
usually the result of linguoversion of one or more maxillary incisors without
any forward mandibular movement, 1 or true skeletal component.
In pseudo Class III malocclusion, Moyers11 suggested
that it is a positional mal-relationship with an acquired neuromuscular reflex
pattern of mandibular closure. Pseudo
Class III malocclusion is usually characterized by Class I or mild Class III
skeletal relationship, retroclined maxillary incisors with upright positioned
lower incisors on the basal bone, incisors in an edge to edge relationship in
centric relation (CR), and an anterior cross bite in centric occlusion (CO).1,8
Graber et al.12 attributed the incisor
interference to the retroclined upper incisors and proclined lower incisors.
During habitual closure to achieve maximum intercuspation, the lingually
inclined maxillary incisors glide down the lingual surfaces of the mandibular
incisors,1 so as to disengage the incisors and bring the posterior
teeth into full occlusion. This results in a forward displacement of mandible
and an anterior crossbite.
Class I molar relationship can exist in both centric relation
and centric occlusion, or there may be a shift from Class I to a Class III
molar relationship on mandibular closure.11 Lee13 pointed
out that the molar relationship could be a Class I at CR and Class III at
CO. On the other hand, Lin14
reported that pseudo Class III malocclusion showed molar Class I relationship
at CO.
When comparing extra-oral photos of patients with pseudo Class
III malocclusion, their profiles appeared quite normal at centric relationship
and slightly concave at centric occlusion.13,15 Lin14 and Turley16 reported that pseudo Class III malocclusion
showed some degree of hereditary tendency. When treating these cases,
elimination of the early incisal interference should be the main treatment
objective. Orthodontic treatment should
be undertaken as soon as possible to avoid adverse effect on the facial
skeleton growth. The treatment can be
accomplished by means of removable or fixed appliances. Turley6 recommended managing these cases with orthopedic treatment with palatal
expansion and a custom protraction headgear. Tsai7 suggested the use
of rapid palatal expansion and standard edgewise appliances to treat an
anterior crossbite in a 7-year-old patient.
Rabie and Gu8 have described a simple method for the early
treatment of pseudo Class III malocclusion in the mixed dentition with fixed
appliances.
This case report is intended to illustrate a way to deal with
pseudo Class III malocclusion by using a modified inverted labial bow appliance
described by Wang in 1996.
Case History and Diagnosis
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A male patient aged 9 years and 6 months, presented with a chief
complaint of the lower anterior teeth overlapping the upper teeth.
The clinical examination revealed a convex profile with a
symmetrical face. Class III molar and canine in centric occlusion with the incisors
in anterior crossbite, deep bite and fair oral health (Fig. 1). In centric relation (CR), the incisors were
in an end-to-end relationship resulting in no overbite and a posterior open
bite. The upper right central incisor
was unerupted due to the presence of two supernumerary teeth. Tooth size discrepancies demonstrated
crowding of -8mm in the upper arch and -2mm in the lower arch.
The panoramic radiograph (Fig. 2) demonstrated normal bone and
tooth development except for the upper right central incisor (due to the two
supernumerary teeth present). Although a
functional forward displacement was present from CR to CO, no sign of
temporomandibular joint dysfunction was detected. The hand and wrist radiograph indicated that
the patient was in a stage before the period of maximum growth spurt (SMI= 1)
and the rate of growth was smallest.
The lateral cephalometric radiograph analysis (Fig. 2) is shown
in Table 1 and illustrates a mild skeletal Class III relationship and retained
maxilla with a normal position of the mandible relative to anterior cranial
base. There was a tendency of a
horizontal growth pattern with skeletal deep bite, an increase in posterior
cranial base, and maxillary and mandibular length. The dental relationship suggested severe
retrusion of upper central incisors, with mild retraction of lower incisors.
The soft tissue relation showed retruded upper and lower lips with an obtuse
nasio-labial angle.
Diagnosis was a pseudo Class III with functional anterior
crossbite and with an impacted upper right central incisor due to the presence
of two unerupted supernumerary teeth.
Treatment Objectives
-
To eliminate CR - CO discrepancy and anterior
crossbite.
-
To correct Class III and establish Class I
canine relationship.
-
To allow eruption of upper right central
incisor.
- To achieve normal overjet, and reduce deep
bite.
-
To resolve crowding.
Treatment Plan
The plan was divided into two stages; the first was directed
towards correction of the functional crossbite to enhance facial growth and
avoid accentuating the Class III discrepancy, in addition to facilitating the
eruption of the right upper central incisor. After eruption of the permanent
teeth, the second stage of treatment would be initiated with fixed orthodontic
appliances for occlusal adjustment and resolving the crowding problem.
Treatment Progress
The patient was referred to the maxillofacial surgeon to remove
the supernumerary teeth. The orthodontic
treatment was conducted by the use of a removable appliance with an inverted
labial bow appliance. 3 (Fig. 3)
An upper impression was
taken with an edge to edge construction bite. The removable appliance was made
of an inverted labial bow and acrylic on the lower incisors, Adams clasps on
molars for retention, Z-spring against upper incisors to move them labially,
and a posterior bite plane to elevate the bite. The inverted labial bow and
Z-spring were activated and the appliance was placed inside the mouth. The
patient was asked to wear the appliance full time except during eating. Oral
hygiene instructions were given, and the appliance was checked and activated
every four weeks.
After three months, the crossbite was completely corrected with
a satisfactory posterior interdigitation. The patient was instructed to wear
the appliance as a night time retainer for three months. Patient was kept under
observation and checked every three months, until completion of permanent teeth
eruption occurred, which took about two years. The sequence of planned
treatment was to start fixed appliances after the eruption of the permanent
teeth, but patient declined due to his satisfaction of the result of the first
stage of treatment. He was referred to extract the wisdom teeth.
The facial and intraoral photographs (Fig. 4) showed an improved
facial profile. The crossbite was corrected with good posterior
interdigitation. All CR - CO shifts were
eliminated and centric occlusion and centric relation were coincident. A
positive overjet was established and deep bite was reduced. Class I canine
occlusion was achieved. The maxillary incisors were proclined producing a
better upper lip prominence. The upper right central incisor had not yet
erupted as at this phase of treatment.
The post-treatment cephalometric radiograph (Fig. 5) illustrated
changes in skeletal relation toward Class I skeletal relationship, with slight
protrusion of the maxilla and retrusion of the mandible by 1o. There was an increase in ramus height which
was reflected on the maxillary-mandibular plane angle. The upper incisors were proclined and the
mandibualr incisors were upright over basal bone (Table 1).
Two years post treatment photographs (Fig. 6), the radiographs
(Fig. 7) revealed the eruption of permanent dentition including the right upper
central incisor and a stable occlusion. There was mild anterior crowding in
both upper and lower arches. The skeletal relationship was improved to normal
range. An increase in the nasiolabial angle and a protrusion of upper and lower
incisors were accomplished.
Many authors have recommended early treatment of Class III
malocclusion which exhibited dental and skeletal components that tend to become
worse with age. They believe that early intervention is an advantage in the
early mixed dentition, as well as in the deciduous dentition. Advantages
include correcting anterior crossbite to allow normal dental base development
and subsequent favorable skeletal growth, preventing habits such as bruxism,
eliminating traumatic occlusion, and reducing the length of treatment time with
fixed appliance.17 The optimum period for treatment suggested is between the ages of 6-9 years.5,12,18
Several clinicians however still avoid early correction of the
pseudo Class III in the deciduous dentition because of poor stability and
unfavorable experiences with behavior of young patients.16 Some practitioners prefer to wait for
permanent maxillary incisors to erupt before starting treatment due to the
natural tendency of the teeth to erupt in a lingual position during dental arch
development.19
The various therapies suggested for the correction of an
anterior crossbite and which may correct skeletal problems in young patients
include face mask therapy,20 chincaps5 and functional
appliances.21 Other alternative treatments include fixed13
and / or removable applainces4, which are effective methods of treating a Class III
incisor malrelation.
Before any treatment, it must be first established that the
malocclusion is treatable. As a general
rule, if the patient cannot make contact of the upper and lower incisors on
closure, there is no possibility of successful appliance treatment and surgical
correction may be considered.
The inverted labial bow appliance was used in this case and it
proved to be a highly effective interceptive treatment for Class III cases,
which are not severe enough to require orthognathic surgery (ANB angle is more
than -20). When the mandible closes, the appliance exerts a
lingually directed force against the lower anteriors, with the Z-spring against
the upper anteriors, thus producing a reciprocal movement. Clinical experience
shows the appliance is comfortable and easily adapted and accepted by the young
patient. The disadvantage is that the success of treatment will depend on
patient cooperation.
In the described case, reduced SNA and normal SNB angles were
present. This finding is similar to that of Guyer et al.10 who reported that the maxilla was retruded in 25%
of the cases. This patient presented with an increased maxillary and mandibular
length, which indicated a tendency to a skeletal Class III that could be
worsened if not treated early. Upper incisors were protruded and lower incisors
were upright, which with other clinical features, distinguish pseudo Class III
type of malocclusion.
The post-treatment records indicated that the forces were transferred to the
mandible and maxilla producing forward movement of the maxilla (SNA = 770),
and backward movement of mandible (SNA = 760) (upper incisor -
maxillary plane = 1140). Two
years post-treatment revealed improvement in skeletal relationships due to
growth improvement of the maxilla, that occurred after correction of the Class
III malocclusion (ANB = 30,
SNA = 800, and SNB = 770).
For retention, the appliance is preferable to be used, although
the developmental changes that occur in the incisor region (normal overbite)
maintain the stability of the results.
- It is important to
distinguish a pseudo Class III from a true Class III malocclusion.
-
In this reported case, a
functional Class III patient was successfully treated with inverted labial bow
appliance.
-
At the end of the
treatment, the correction of anterior crossbite and elimination of the
mandibular displacement were obtained.
-
Anterior crossbite
should be corrected once recognized to allow for normal dental base development
and subsequent favorable skeletal growth.
- Mamandras AH, Magli
LA. Orthodontic treatment of pseudo Class III malocclusion: A case report. J Canad Dent Assoc 1984; 779 -781.
- Grimm SE. Treatment of a pseudo Class III relationship
in the primary dentition: A case
history. J Dent Child 1991; 484 - 488.
- Wang F. Inverted labial bow appliance for Class III
treatment. JCO 1996; 487-492.
- Ngan P, Hgg U, Yiu C,
Merwin D, Wei S. Treatment response to
maxillary expansion and protraction. Eur
J Orthod 1966; 18: 151 - 168.
- Allen RA, Connolly IH,
Richardson A. Early treatment of Class
III incisor relationship using the chincap appliance. Eur J Orthod 1993; 15: 371 - 376.
- Turley PT. Early management of the developing Class III
malocclusion. Aust Orthod J 1993; 13: 19
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- Tsai HH. Treatment of anterior crossbite with
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- Rabie AB, Gu Y.
Diagnostic criteria for pseudo Class III malocclusion. Am J Orthod Dentofac Orthop 2000; 117: 1 - 9.
- Angle EH. Treatment of malocclusion of the teeth and
fractures of the maxillae. Angle's System. 6th ed. Philadelphia: SS White Dental Manufacturing,
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- Guyer EC, Ellis EE,
McNamara JA Jr, Behrents RG. Components
of Class III malocclusion in juveniles and adolescents. Angle Orthod 1986; 56: 7 - 30.
- Moyers RE. Handbook of orthodontics. 4th ed.
Chicago: Year Book 1982; 410 - 415.
- Graber TM, Rakosi TH,
Petrovic AG. Dentofacial orthodontics
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- Lee BD. Correction of crossbite. Dent Clin North Am 1978; 22: 647 - 668.
- Lin JJ. Differential diagnosis and management of
anterior crossbite. Beijing - Hong Kong
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- Sharma PS, Brown RV. Pseudo mesiocclusion: Diagnosis and treatment. J Dent Child 1968; 35: 385 - 392.
- Turley PK. Orthopedic
correction of Class III malocclusion: Retention and phase II therapy. J Clin
Orthod 1996; 30: 313 - 324.
- Giancotti A, Maselli A,
Mampieri G, Spano E. Pseudo Class III malocclusion treatment with Balters
Bionator. J Orthod 2003; 30:203-215.
- Nanda R. Protraction of maxilla in rhesus monkeys by
controlled extra oral forces. Am J
Orthod Dentofac Orthop 1978; 74: 121 - 141.
- Rabie AB, Gu Y. Management of pseudo Class III malocclusion
in Southern Chinese Children. Br Dent J
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- dos Santos-Pinto AD,
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