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International J. of Healthcare & Biomedical Research, Volume: 1, Issue: 3, April 2013, Pages 180-189
“ACTIVATOR: SIMPLE YET EFFECTIVE FUNCTIONAL APPLIANCE FOR SKELETAL CLASS II
CORRECTION: CASE REPORT”
1Dr.
Falguni Mehta *, 2Dr. Dolly Patel, 3Dr. Nishit Mehta
1Professor,
Dept of orthodontics & Dentofacial orthopaedics
Govt Dental College & Hospital, Ahmedabad, Gujarat , India
2Professor & Head, Dept of orthodontics & Dentofacial orthopaedics
Govt Dental College & Hospital, Ahmedabad, Gujarat , India
3Third year post graduate student
Dept of orthodontics & dentofacial orthopaedics, Govt Dental College & Hospital,
Ahmedabad, Gujarat, India
*Corresponding author: Dr. Falguni Mehta ; Email id :[email protected]
................................……………………………………………………………………………………………...
ABSTRACT:
A Class II malocclusion may result from a mandibular deficiency, maxillary excess or a combination of both, but the most
common finding is mandibular skeletal retrusion. Functionaljaw orthopaedic appliances are designed to encourageadaptive skeletal
growth by maintaining the mandible in a corrected forward position. The activatordeveloped by Andresen is one of the most
widely used. A 12-year-old boy with skeletal Class II malocclusion, a low mandibular planeangle was treated with growth
modulation by activator followed by fixed orthodontics for detailing of occlusion.The major effects of the activator treatment in
this case has been due to increase in condylar growth and in mandibular base length.Further non-extraction fixed orthodontic
treatment for proper interdigitation of the dentition also help to maintain the stability of the satisfactory results achieved in this
type of cases.
KEY WORDS: class II Malocclusion , mandibular retrognathism , functional jaw orthopaedics , Activator
………………………………………………………………………………………………...............................
INTRODUCTION
discrepancy1. The success of treatment with a functional
Class II malocclusions are one of the most common
appliance relies
problems in orthodontic treatment.Treatment of class
favourable
II malocclusion has always been an enigma to the
functional appliance usually lasts for 9 to 12 months and
orthodontic fraternity. It ranges from a simple
requires a proper retention time to ensure complete
functional appliance to surgical correction. There are
musculoskeletal adaptation. A second stage of treatment
a variety of effective treatment modalities to correct
with a full-fixed appliance is often required to achieve
them,
proper alignment and good interdigitation of the
ranging
from
headgear
and
functional
on the patient's
mandibular
growth.
cooperation and
Treatment
with
a
appliances to surgical options, depending on the site ,
dentition2.
age of the patient and severity of problem. Functional
By holding a deficient mandible forward and forcing the
appliances are commonly used for the treatment of
patient to function with lower jaw forward , functional
Class II malocclusions with mandibular deficiency.
appliance can stimulate or accelerate the forward
The treatment goals for these appliances are to reduce
mandibular growth .There are variety of removable
the large overjet and correct the sagittal skeletal
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International J. of Healthcare & Biomedical Research, Volume: 1, Issue: 3, April 2013, Pages 180-189
functional appliances including activator , Robins’
•
aim
was
to
correct
monobloc, bionator ,bass appliance ,twin block1,etc.
discrepancy
The activator and its successors provide a greater
functional appliance.
contact area with the mandibular teeth and lingual
•
mucosa, and thus are more effective in stimulating the
patient to position the mandible forward constantly.
Here, we are presenting a case of a class II
with
the
growth
sagittal
skeletal
modulation
with
To achieve and maintain Angle’s class I molar
and canine relationship bilaterally
•
To achieve normal overjet and overbite.
•
To align and level upper and lower arches and
skeletal malocclusion treated by using the time-tested
final finishing and detailing of the occlusion with
activator appliance. Despite of simple design,
fixed mechanotherapy.
activator can be used to change dental relationship in
3
TREATMENT PROGRESS
all three planes of space with proper adjustments .
12 year male with a Class II malocclusion and
DIAGNOSIS
retrognathic mandible was treated first withactivator for 1
A 12 year old male patient reported with the chief
year and 1 month. Construction bite with single
complaint of forwardly placed upper front teeth.There
advancement was taken and activator was delivered with
was history of trauma with Ellis class I fracture in
proper patient
relation to upper left central incisor. The patient had a
compliance and maintained good oral hygiene. . After
skeletal Class II malocclusion with severe mandibular
treatment period of 1 year and 1 month with activator,
retrognathism,
plane
patient showed improvement in soft tissue profile with
angle(table-1,2,3). The lips were competent, with non-
class I molar and canine relationship bilaterally(Fig 2-a to
consonant smile arc and convex soft tissue profile(fig
h).Selective trimming of acrylic portion was done to allow
1-a,b,c) . patient had mixed dentition in late
eruption of posterior teeth to eliminate the excessive curve
transitional period with Angle’s class II molar aswell
of Spee in lower arch. The activator successfully resolved
as canine relationship with increased overjet(14 mm)
the problem of the retrognathicmandible with favourable
andoverbite(8 mm)(fig 1-d,e.f,g,h) .curve of Spee of 4
mandibular growth.
mm was present. His maxillary incisors were tipped
After achieving the functional correction of skeletal
labially of their bony base, and the mandibular incisors
discrepancy, the full-fixed orthodontic appliance (022”
were tipped lingually(table-1). There was spacing in
MBT) along with inclined plane was put in place for 1
upper anterior region. Mesiobuccalrotations were
year to stabilize the occlusion without extraction(fig 3- a
present in upper premolars. The maxillary and
to h). Once the occlusion was stabilized with good
mandibular midline were coincident with facial
posterior interdigitation , fixed appliances were removed
and
average
mandibular
4
instuctions. The patient
had good
midline.patient was in CVMI stage III with positive
and patient was kept under retention. Since the patient was
VTO.
in growing phase , along with upper Hawleys’ plate with
TREATMENT PLANNING
inclined plane , night time wear of activator was
•
Since the patient was in growing stage with
advocated.
favourable growth pattern and positive VTO,
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International J. of Healthcare & Biomedical Research, Volume: 1, Issue: 3, April 2013, Pages 180-189
TREATMENT RESULTS
activator in correcting a class II malocclusion in this
At the end of the treatment the patient had good
patient include :
functional , mutually protected occlusion with canine
•
Stimulation of the mandibular growth.5,6,7,8,9,13
and molar in Angles’ class I relationship , normal
•
Redirection of the anterior and
verticaldentoalveolar growth of maxilla.6,10,11
overjet and overbite (fig 4-d,e,f,g,h) and good facial
proportions(fig 4-a,b,c , table-4).
•
Superimposing the pre and post-treatment lateral
cephalograms (fig. 5) demonstrated a
considerable
Redirection of the anterior and
verticaldentoalveolar growth of mandible. 5,10,12
•
Remodelling changes in TMJ.13
downward and forward growth of mandible reducing
CONCLUSION
ANB angle to 2˚ from
It is generally agreed that functional appliances can be
6˚.Mandibular
base length
increased from 76 mm to 85 mm(table-3).
used successfully to treat skeletal class II malocclusions in
DISCUSSION
growing and cooperative patients. The ideal case for such
Functional appliances are effective in treating skeletal
treatment is:
class II malocclusion, particularly in cases with
•
retrognathic mandible functional appliances are of
greatest clinical benefit in actively growing patients
Class II division I malocclusion withretrognathic
mandible Low to average mandibular plane angle
•
Upright or linguallytipped lower incisors.
with good compliance.In this case ,the muscular force
The activator can solve many problems that become more
generated by the forward mandibular positioning was
severe if left untreated.The Activator cannot create a large
transferred to the maxillary and the mandibular teeth
mandible from a small one, but it can help the patient
through the acrylic body and labial bow. These forces
achieve the optimal size consistent with morphogenetic
which were transmitted through the teeth to the
pattern14. The restoration of the normal function is a major
periosteum and bone were responsible in producing a
contribution to improvement in the morphofunctional
restraining effect on the forward growth of maxilla ,
interrelationship.
while stimulating the mandibular growth and causing
maxilla mandibular dentoalveolar adaptation.
Both skeletal and dentoalveolar changes has been achieved
The major effects of the activator treatment in this case
by activator therapy.Due to favourable growth and good
has been due to increase in condylar growth and in
compliance, his facial profile became orthognathic with
mandibular base length. The combination of these
treatment. The overbite decreased because of molar
effects resulted in the permanent anterior displacement
extrusion and inhibition of incisor eruption which level the
of mandible. The activator also had an influence on
curve of Spee. The uprighting of the upper incisors also
dentition. By inhibiting the maxillary dentoalveolar
helped to reduce the overjet. Further non-extraction fixed
vertical growth and encouraging the mandibular
orthodontic treatment for proper interdigitation of the
dentoalveolar mesial
dentition will also help to maintain the stability of the
and vertical development , the
activator resolved the class II malocclusion to class I
satisfactory results achieved in this type of cases.
malocclusion. The possible mechanisms for the
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LEGENDS:
Figure 1: Pre Treatment Photographs
Figure 2 : Post functional correction
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Figure 3 : fixed appliances in situ
Figure 4 : Post Treatment Photographs
Figure 5 : Pre Treatment and Post treatment lateral cephalogram Super Imposition
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TABLE 1 – CEPHALOMETRIC DATA
MEAN
PRE
POST
TREATMENT
TREATMENT
SNA
82° ± 2°
74°
730
SNB
80° ± 2°
68°
710
ANB
2°
U1-NA
22°
U1-NA
4mm
L1-NB
25°
L1-NB
4mm
6°
20
44°
11mm
180
6mm
25°
6mm
25°
5mm
Interincisal
Angle
130°
114°
GoGn-SN
32˚
29˚
Occ-SN
14˚
L1-APog
−1.2mm
18˚
115°
31˚
22˚
± 1.4mm
-1mm
3 mm
FMA
25°
19°
220
IMPA
90°
93°
98°
FMIA
65˚
66˚
60˚
NA-APg
-8˚-10˚
5˚
0˚
NPg-AB
-9˚-0˚
-12˚
-4˚
NPg-FH
82˚-95˚
84˚
96˚
Y-Axis
53˚-66˚
60˚
60˚
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Table 2-CEPHALOMETRIC ANALYSIS – Mc NAMARA ANALYSIS
MEAN
PRETREATMENT
POST TREATMENT
MAXILLA TO CRANIAL BASE
A)
Nasolabial angle
102±8
100
108
A)
Cant of upper lip
Female:
10
0
-3 mm
-6 mm
Male:
A)
Point A to N- perpendicular
0-1 mm
MAXILLA TO MANDIBLE
ANTEROPOSTERIOR
A)
Maxillary length (Co-A)
90 mm
96 mm
A)
Mandibular length (Co-Gn)
109 mm
121 mm
A)
Maxilla mandibular differential
19 mm
25 mm
Small:20-23
Medium 27- 30
Large:30-33
VERTICAL
A)
Lower AFH (ANS-Me)
62 mm
71
B)
Mandibular plane angle (FH-Go-Me)
22±4
19
22
C)
Facial axis angle (Ptm-Gn-Ba-N perpendicular)
0±3.5mm
-4
-5
Small:
-10 mm
-12 mm
M
MANDIBLE TO CRANIAL BASE
Pog to N perpendicular
Medium:
Large:
DENTITION
A)
Maxillary incisor to point A
4-6mm
7 mm
5 mm
A)
Mandibular incisor to A-Pog
1-3mm
-2 mm
3 mm
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Table 3-Rakosi’s Analysis
ANALYSIS OF FACIAL SKELETON
MEASUREMENT
MEAN
PRE-TREATMENT
POST-TREATMENT
SADDLE ANGLE
123 +5
130
130
ARTICULAR ANGLE
143 +6
146
146
GONIAL ANGLE
128+ 7
119
121
U- GONIAL ANGLE
52 -55
51 mm
51 mm
L – GONIAL ANGLE
72 – 75
68 mm
70 mm
POSTERIOR FACE HEIGHT
76 mm
85 mm
ANTERIOR FACE HEIGHT
117 v
131 mm
JARABACK’S RATIO
62-65%
64.95 %
64.88 %
ANTERIOR CRANIAL BASE
LENGTH
71 mm
73 mm
78 mm
POSTERIOR CRANIAL BASE
LENGTH
32-35 mm
39 mm
44 mm
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ANALYSIS OF THE JAW BASES
SNA ANGLE
81
74
73
SNB ANGLE
79
68
71
ANB ANGLE
2
6
2
BASAL PLANE ANGLE
25
21
23
INCLINATION ANGLE (Pn
TO ANS-PNS)
85
81
81
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Date of submission: 2 March 2013
Date of provisional acceptance: 11 March 2013
Date of Final acceptance: 30 March 2013
Date of Publication: 03 April 2013
Source of support: Nil; Conflict of Interest: Nil
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