Soft tissue facial profile changes following functional appliance therapy

Abstract

The aim of this study was to evaluate changes in the facial profile resulting from the use of a twin block (TB) functional appliance. The sample comprised 38 patients (24 males and 14 females) with a Class II division 1 malocclusion. Nineteen subjects were treated with a functional appliance while the remaining 19, who did not undergo any intervention, served as the control. The mean age of the treated group was 9.5 years (SD 10 months) and of the control group 9.9 years (SD 13 months). Lateral cephalograms were obtained for all subjects at the initial consultation and again after one year. The changes in facial profile, resulting from treatment with the TB, were analysed after the influence of growth had been taken into account.
The results showed a significant improvement in the facial profile, which closely followed the underlying dentoskeletal changes. Thus, the most significant effects were a total facial profile improvement, retraction of the upper lip and anterior movement of soft tissue pogonion (P < 0.05). Subjects treated with a TB appliance achieved improved facial harmony, but such changes were not observed in the control group.

Full text

European Journal of Orthodontics 28 (2006) 35–41
doi:10.1093/ejo/cji067
Advance Access publication 19 August 2005
© The Author 2005. Published by Oxford University Press on behalf of the European Orthodontics Society.
All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org.
Soft tissue facial profi le changes following functional
appliance therapy
Cátia Quintão, Ione Helena V. P. Brunharo, Robsmar C. Menezes and
Marco A. O. Almeida
Department of Orthodontics, University of Rio de Janeiro, Brazil
SUMMARY The aim of this study was to evaluate changes in the facial profi le resulting from the use of a
twin block (TB) functional appliance. The sample comprised 38 patients (24 males and 14 females) with
a Class II division 1 malocclusion. Nineteen subjects were treated with a functional appliance while the
remaining 19, who did not undergo any intervention, served as the control. The mean age of the treated
group was 9.5 years (SD 10 months) and of the control group 9.9 years (SD 13 months). Lateral
cephalograms were obtained for all subjects at the initial consultation and again after one year. The
changes in facial profi le, resulting from treatment with the TB, were analysed after the infl uence of growth
had been taken into account.
The results showed a signifi cant improvement in the facial profi le, which closely followed the underlying
dentoskeletal changes. Thus, the most signifi cant effects were a total facial profi le improvement, retraction
of the upper lip and anterior movement of soft tissue pogonion (P < 0.05). Subjects treated with a TB
appliance achieved improved facial harmony, but such changes were not observed in the control group.
Introduction
Improving facial aesthetics is one of the aims of orthodontic
treatment. However, changes in the facial profi le may occur
due to many factors, such as dental movement or growth
(Rains and Nanda, 1982). Subjects presenting with a Class II
division 1 malocclusion have specifi c clinical characteristics,
such as an increased overjet, and an unfavourable profi le
which may produce negative feelings of self-image and self-
esteem (Shaw, 1981; Tung and Kiyak, 1998). Appliance
therapy to correct such a malocclusion should ideally be
directed towards addressing the dentoskeletal disharmony,
in order to obtain a favourable facial aesthetic result.
The literature contains a large number of studies
investigating the mechanisms of action and the effects of
different orthopaedic appliances designed to correct Class
II division 1 malocclusions. Most of these, however, have
concentrated on recording the dentoskeletal changes
(Vargevik and Harvold, 1985)
and have ignored the effects
on the soft tissue facial profi le (Morris et al., 1998). The
dentoskeletal effects of the twin block (TB) functional
appliance on Class II malocclusions have been well
documented (Clark, 1988; Mills and McCulloch, 1998).
The aim of the present study was to evaluate changes in
the soft tissue facial profi le, in subjects with a Class II
division 1 malocclusion, resulting from early treatment with
a TB appliance.
Subjects and methods
The sample comprised 38 subjects, prospectively recruited,
from those awaiting treatment at the Orthodontic Post
Graduate Clinic, Dental School, Universidade do Estado do
Rio de Janeiro. Nineteen patients were treated with a TB
functional appliance and the other 19 formed the control
group. Ethical approval for the study was obtained from the
Ethical Committee of the University of Rio de Janeiro. The
following inclusion criteria were applied:
1. Skeletal Class II relationship (ANB > 4 degrees).
2. Class II incisor (overjet ≥ 6 mm), canine and molar
relationship.
3. No previous history of orthodontic treatment.
4. Patients in the following epiphyseal stages, as defi ned by
Ferreira (1998): FP, FM, G1 and Psi. These all
characterize the initial stages of the pubertal growth
spurt.
The treated group comprised 12 boys and seven girls
with a mean age of 9.5 years (SD 10 months), and the
control group 12 boys and seven girls with a mean age of
9.9 years (SD 13 months). The difference in the mean age
of subjects in each group was not statistically signifi cant
(P = 0.28). The active treatment time was 12 months
(SD 1 month).
The design of the TB, used in the present study (Figure 1)
has been previously described (Brunharo and Quintão,
2001). The initial working bite was recorded with the
mandible postured forward by 4 mm. However, in those
with large overjets, the TB was re-activated six months after
the start of treatment, by addition of acrylic to the upper
block. The subjects were instructed to wear the appliance
full-time and asked to complete a time sheet to monitor
compliance. The control group underwent treatment at the
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C. QUINTÃO ET AL.
36
‘ideal’ stage of development, conforming to the approval
granted by the local ethical committee.
Cephalometric radiographs were taken four weeks before
the start of active treatment (T1) and 12 months (SD one
month) later (T2), for all subjects in the study. At T2, care
was taken to ensure the subjects did not posture their
mandibles.
Cephalometric radiographs were taken in profi le
(Broadbent, 1931). The subjects were positioned in the
natural head posture with the mid sagittal plane 90 degrees
to the X-rays and Frankfort plane. The lips were relaxed and
lying in a rest position (Yoshida machine, model Panoura
10 CSU with variations of 10 mAs and 0.8 and 1.2 seconds,
with 85 and 90 Kvp).
The lateral cephalogram was subsequently scanned using
an Epson Expression 1680 scanner (resolution 1600 × 3200
dpi) transparency unity (Epson American Inc., Long Beach,
California, USA). The radiographs were analysed using the
Radiocef 2.0
®
Memory studio computer program (Radiocef,
Floresta, Belo Horizonte, Minas Gerais, Brazil). This
program generated a customized analysis for each
cephalometric radiograph (Figures 2 and 3). A total of 31
variables were evaluated.
A vertical reference line (VL), originating from sella
turcica (S) and perpendicular to the sella–nasion (S–N) line
was constructed. Both lines were used for superimposition
of the cephalometric tracings. A mean tracing for the
treatment and control groups was produced at T1 and T2,
applying the principles of Holdaway’s visual treatment
objective (Holdaway, 1983, 1984). The mean change was
used at T2 in order to visualize the alterations (Figure 4).
The cephalometric analyses applied to the radiographs were
based on the analyses of Steiner (1953, 1960) and Ricketts
(1960, 1961).
All measurements obtained were tabulated for evaluation
and statistical analysis using the Primer of Biostatistics
version 4.0 (© 1996 McGraw Hill) for Windows. To
standardize measurements and minimize error, the
digitization was performed by a single operator (RCM).
The angular and linear measurements were recorded in
degrees and millimetres, respectively.
To evaluate the method error, 10 pairs of radiographs (T1
and T2) were randomly selected. The mean error and the
SD between the paired tracings were obtained. An intraclass
correlation coeffi cient (ICC) was calculated and a value
higher than 0.810, for a confi dence interval of 95 per cent,
was found for SNA, L–HF variables and nasolabial angle.
The mean variation coeffi cient for these variables was 0.96,
1.88 and 4.66 per cent, respectively, demonstrating a low
method error.
Descriptive statistics included the mean and SD. A non-
paired Student’s t-test was used to verify the homogeneity of
the analysed groups, and the changes resulting from growth
and treatment at the end of the study period were evaluated.
Figure 1 The twin block functional appliance used. (a) anterior, (b) lateral, (c) upper occlusal,
and (d) lower occlusal views.
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37
PROFILE AND FUNCTIONAL THERAPY
The linear correlation coeffi cient (r) was used to evaluate
the correlation between the variables being studied and the
paired Student’s t-test to verify their signifi cance. The level
of signifi cance was P < 0.05.
Results
The cephalometric variables used for both the treated and
control group at T1 are listed in Table 1. The non-paired
Student’s t-test demonstrated that there were no signifi cant
differences between the groups at T1, highlighting the
homogeneity of the groups.
Changes in the variables used at T2 (T2–T1) resulting
from growth and treatment are listed in Table 2 and shown
in Figures 5 and 6. These demonstrate the signifi cance of
the variable VL–Ul (P < 0.05), indicating that the upper lip
was retropositioned following TB therapy. The upper incisor
position (1/NA, mm and angle) also demonstrated signifi cant
differences (P < 0.001), which may be correlated with the
change in upper lip position. In the treated group (Table 2)
1/NA angle changed signifi cantly, as did the VL–Ui distance,
characterizing upper incisor retroclination, which also
produced a signifi cant change in upper lip inclination (L/HF
angle). A vertical positioning of the upper incisors occurred,
followed by the upper lip, confi rmed by a statistically
signifi cant linear correlation (r = +0.75) between the VL–
Ul/VL–Ui variables. The change in upper lip position was
not believed to be induced by skeletal changes (SNA and
maxillary length, defi ned by Co–A distance, did not change
signifi cantly between T1 and T2). Furthermore, none of the
variables used to evaluate maxillary changes (SNA and
Co–A) showed any signifi cant differences at T2.
The TB appliance signifi cantly improved the Z angle (P
< 0.01), refl ected in reduced soft tissue facial convexity.
The signifi cant increase in mandibular length, measured by
Co–Gn (P < 0.05), between T1 and T2, may have contributed
to this improvement in profi le. The variable L/HF increased
signifi cantly between T1 and T2 (P < 0.05) contributing to
Figure 2 Linear and angular cephalometric points measured: SNA,
sella–nasion–point A angle; SNB, sella–nasion–point B angle; ANB, point
A–nasion–point B angle; Co–A, maxillary length; Co–Gn, mandibular real
length; 1/NA, upper incisor–nasion/point A line (angle and mm); lower
incisor–nasion/point B line (angle and mm); Z angle, porion point/orbital
point (Frankfort plane)–line E (Ricketts line profi le) angle; L/HF, Frankfort
plane to most anterior point of the upper lip; N/HF, Frankfort plane–nose
base angle.
Figure 4 Pre-treatment superimposed mean cephalometric tracings
for both groups (grey), after a 12-month study period for the control
group (dotted line), and post-treatment for the twin block group
(black).
Figure 3 Linear cephalometric profi le changes measured: VL to SN,
vertical line to sella–nasion line (90 degrees); VL–Prn, distance of the
most anterior point of the nose to VL; VL–UlF, distance of most posterior
point of the lower border of the nose to VL; VL–Ul, distance of the
most anterior point of the upper lip to VL; VL–Ui, distance of the most
anterior point of the upper incisor to VL; VL–Ll, distance of the most
anterior point of the lower lip to VL; VL–LlF, distance of the
most posterior point of the lower border of the lip to VL; VL–pog,
distance of pogonion point to VL; VL–pog’, distance of tegumental
pogonion to VL.
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C. QUINTÃO ET AL.
38
the change in soft tissue profi le. The signifi cant increase in
S line–upper lip (P < 0.001) and upper labial position (P <
0.001) further contributed to the changes observed in the Z
angle and consequent reduction in facial convexity. Thus, it
would appear that the change in soft tissue profi le was
primarily the result of upper lip modifi cation. However,
skeletal variable changes also contributed to this profi le
change, as the ANB angle signifi cantly reduced (P < 0.001)
and mandibular length increased (P < 0.05).
Whilst a signifi cant increase in lower incisor projection
occurred (1/NB angle; P < 0.05), no change was observed
in lower lip position. A correction in the molar relationship
was obtained in 15 of the 19 treated patients (80 per cent).
Discussion
Soft tissue facial profi le
It could be expected that the skeletal changes achieved
would result in similar changes taking place in the soft
tissues (Riedel, 1957; Rains and Nanda, 1982). However,
some authors have stated that proportional changes or facial
profi le improvement do not necessarily follow marked
dental/skeletal changes (Burstone, 1959; Subtelny, 1959).
There is also a large degree of individual variation with
regard to treatment response (Pangrazio-Kubersh, 1985).
Subjects with Class II malocclusions generally present with
convex facial profi les and a retrognathic soft tissue pogonion
associated with mentalis activity to achieve an anterior lip
seal (Ward, 1994). There was an increase in the VL-Prn
measurements in both groups, due to nasal growth alone.
The mean increase of 2.5 mm/year was greater than the 1mm/
year suggested by Subtelny (1961).
Upper and lower lip
In the treated group, a signifi cant change in upper lip
inclination and position was observed due to upper incisor
retroclination. There was a statistically signifi cant linear
Table 1 Descriptive statistics for the skeletal variables at the initial (T1) and fi nal (T2) time-points for the control and the twin block
(TB) groups.
Cephalometric variable TB (n = 19) Control (n = 19) P value Signifi cance
T1 T2 T1 T2
Mean SD Mean SD Mean SD Mean SD
Linear measurements
VL–Prn 92.83 4.81 95.40 4.70 90.11 5.04 93.01 5.30 0.097 ns
Vertical line–upper lip sulcus (VL–UlS) 77.56 4.90 79.61 5.12 75.60 4.84 77.84 5.09 0.223 ns
Vertical line–upper lip (VL–Ul) 81.09 6.48 82.41 6.64 77.45 5.31 80.24 5.54 0.066 ns
Vertical line–lower lip (VL–Ll) 71.56 7.50 75.48 8.13 69.27 5.61 71.48 6.83 0.294 ns
Vertical line–lower lip sulcus (VL–LlS) 58.38 7.74 62.00 8.50 56.70 5.95 58.48 7.43 0.459 ns
VL–pog’ 58.21 8.93 61.45 9.33 56.84 7.19 58.68 8.56 0.605 ns
Angular measurements
Z angle 66.43 5.06 69.22 4.68 67.87 4.61 67.73 5.35 0.366 ns
L/HF 68.89 14.08 72.40 12.29 75.89 8.64 73.92 8.02 0.075 ns
N/HF 31.79 6.90 29.98 6.75 32.13 7.29 32.31 6.70 0.885 ns
Nasolabial angle 100.68 16.55 102.38 12.40 108.33 10.92 106.23 9.88 0.103 ns
Steiner
(Line S)–upper lip 4.25 2.27 2.84 2.22 3.17 2.18 3.23 2.40 0.160 ns
(Line S)–lower lip 3.76 3.45 4.42 3.11 3.07 3.62 3.47 3.63 0.552 ns
Ricketts
Upper labial position 2.39 2.39 0.95 2.07 1.45 2.61 1.45 2.65 0.271 ns
Lower labial position 2.88 3.51 3.43 3.05 2.30 3.75 2.33 3.53 0.623 ns
Skeletal component
ANB 6.98 1.68 5.65 1.75 6.56 1.72 6.60 1.88 0.455 ns
SNA 82.30 4.12 82.35 4.58 81.57 4.39 82.52 4.72 0.598 ns
SNB 75.32 3.75 76.70 4.02 75.00 3.49 75.92 3.72 0.789 ns
Maxillary length 93.83 3.18 96.05 3.83 91.07 5.04 93.49 4.36 0.052 ns
Mandibular length 113.25 4.03 118.47 3.84 110.6 5.73 113.42 6.14 0.108 ns
Dental component
l/NA (º) 28.96 6.30 20.99 4.85 27.44 7.24 27.40 6.72 0.495 ns
l/NA (mm) 5.59 2.28 3.64 1.96 5.34 2.93 5.54 2.50 0.773 ns
/l–NB (º) 31.55 5.26 34.67 4.16 31.33 5.51 32.04 5.66 0.901 ns
/l–NB (mm) 5.80 2.73 6.95 2.39 5.78 2.28 6.06 2.6 0.983 ns
ns, non signifi cant.
VL–Prn, distance of the most anterior point of the nose to the vertical line; VL–pog’, distance of tegumental pogonion to the vertical line; L/HF,
Frankfort plane to the most anterior point of the upper lip; N/HF, Frankfort plane–nose base angle.
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39
PROFILE AND FUNCTIONAL THERAPY
correlation (r = +0.75) between the VL–Ul/VL–Ui
variables. Similarly, Roos (1977) demonstrated a high
correlation between incisor retraction and upper lip
movement. No statistically signifi cant change occurred in
any of the lower lip variables in relation to the treated or
control group.
Menton
There was a mean increase of 1.29 degrees (P < 0.05) in the
S–N/Go–Me angular measurement. There was also a small
increase in lower anterior face height, resulting from a
clockwise rotation of the mandible, with a downward and
backward displacement of pogonion. However, the
mandibular plane increase did not reduce the Vl–pog’ linear
measurement which showed an insignifi cant increase of
0.70 mm. There was a strong linear correlation (r = +0.75)
with the VL–pog’ linear measurement, but this was not
statistically signifi cant.
Total facial profi le
A signifi cant improvement was seen in the profi le of the treated
group (Figure 4). Only minor facial changes were observed in
the control group during the study period, which did not reach
statistical signifi cance. Conversely, the treated group exhibited
greater changes, thus characterising the effects of treatment
(the upper lip retraction and forward advancement of soft
tissue pogonion; Figure 4). The variables associated with the
lower third (VL–Ll, VL–LlF and VL–pog’) showed forward
movement in relation to the middle third (VL–Prn, VL–UlF
and VL–Ul) of the face. A positive correlation was found
between these variables (r = +0.84), with the largest changes
observed in the soft tissues of the treated group. Rabie
et al. (2003) showed that, in animals, anterior mandibular
positioning accelerates and increases chondrocyte
differentiation as well as cartilaginous matrix formation in
the mandibular condyle, implying that functional appliance
therapy may induce a true increase in mandibular growth.
Table 2 Descriptive statistics of the differences between the mean cephalometric values for the initial (T1) and fi nal (T2) measurements
in the control and the twin block (TB) groups.
Cephalometric variable TB Control Difference Signifi cance P
T1 T2 T1 T2
Mean SD Mean SD
Linear measurements
VL–Prn 2.57 1.66 2.90 2.61 –0.34 ns
Vertical line–upper lip sulcus (VL–UlS) 2.05 1.32 2.24 2.56 –0.19 ns
Vertical line–upper lip (VL–Ul) 1.31 2.05 2.79 2.42 –1.48 *
Vertical line–lower lip (VL–Ll) 3.92 3.16 2.21 4.54 1.70 ns
Vertical line–lower lip sulcus (VL–LlS) 3.63 2.25 1.78 4.05 1.85 ns
VL–pog’ 3.24 2.08 1.84 3.76 1.40 ns
Angular measurements
Z angle 2.79 2.95 –0.14 3.86 2.93 *
L/HF 3.50 5.09 –1.97 4.76 5.47 **
N/HF –1.80 5.23 0.13 6.35 –1.93 ns
Nasolabial angle 1.70 7.68 –2.09 8.70 3.79 ns
Steiner
(S Line)–upper lip –1.24 0.98 0.27 1.00 –1.51 ***
(S Line)–lower lip 0.66 1.94 0.21 2.34 0.45 ns
Ricketts
Upper labial position –1.38 0.98 –0.08 1.19 –1.29 ***
Lower labial position 0.55 1.95 0.03 2.38 0.52 ns
Skeletal component
ANB –1.33 0.68 0.03 1.20 –1.36 ***
SNA 0.05 1.07 0.95 2.37 –0.90 ns
SNB 1.38 1.05 0.92 2.01 0.46 ns
Maxillary length 2.22 2.89 2.42 2.31 –0.20 ns
Mandibular length 5.22 3.26 2.82 2.80 2.40 *
Dental component
l/NA (º) –7.98 4.79 –0.05 3.37 –7.93 ***
l/NA (mm) –2.04 2.10 0.20 1.21 –2.24 ***
/l–NB (º) 3.13 3.04 0.71 3.15 2.41 *
/l–NB (mm) 1.15 1.21 0.27 1.44 0.87 ns
ns, non signifi cant; *P < 0.05; **P < 0.01; ***P < 0.001.
VL–Prn, distance of the most anterior point of the nose to the vertical line; VL–pog’, distance of tegumental pogonion to the vertical line; L/HF,
Frankfort plane to the most anterior point of the upper lip; N/HF, Frankfort plane–nose base angle.
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C. QUINTÃO ET AL.
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Clinically, the fi xed-functional Herbst appliance has been
shown to produce an increase in mandibular growth
(Pancherz, 1979, 1981). However, such effects with
removable functional appliances are questionable, as their
action appears to be intermittent. According to Clark (1995),
sagittal discrepancy correction is encouraged with the TB
appliance by ‘release’ of the posterior teeth, which is
thought to allow the expression of any favourable anterior
mandibular growth. Chen et al. (2002), in a systematic
review of the effects of functional appliances, reported that
these appliances have little effect on mandibular length.
However, signifi cant methodological differences between
the studies make a true comparison diffi cult. In the current
investigation, a mean increase of 5.22 mm per year was
observed in mandibular length (Co–Gn) with the TB
appliance (Table 2), corroborating the fi ndings of Lund and
Sandler (1998) and Toth and McNamara (1999). A
statistically signifi cant decrease in ANB angle was found,
which led to a reduction in facial convexity. This was due
not only to mandibular advancement but also to a degree of
maxillary restraint.
The 1/NA variables reduced in the treatment group
compared with the control group (Table 2). The upper
incisors were retroclined during treatment, which aided
overjet reduction. The lower incisors (1/NB) proclined
during treatment, further contributing to the reduction in
overjet. Lund and Sandler (1998), Mills and McCulloch
(1998), Toth and McNamara (1999) and Trenouth (2000) all
found similar effects. These may need to be corrected during
a second phase of orthodontic treatment, involving premolar
extractions, in order to upright the lower incisors and
enhance stability (Tulloch et al., 1998).
Timing of treatment
Previous studies have suggested that any attempt to change
growth is best achieved at the peak of the pubertal growth
spurt (Gianelly, 1995; Baccetti et al., 2000), which is
normally 12 and 14 years of age for girls and boys,
respectively. However, the mean age of subjects in this
study was 9.5 years. There were a perceived number of
reasons for the timing of treatment in the current study:
1. It was felt that a greater degree of skeletal correction
could be obtained at this stage of development. However,
for a complete Class II correction, an extended growth
period would be needed (McNamara and Brudon,
1993).
2. The stability and comfort of the TB appliance is greater
when the primary molars are present. During the mixed
dentition phase of development, it may be diffi cult to
maintain stability of the appliance due to the exfoliation
of the primary teeth (Clark, 1995).
3. Younger patients adapt more readily to functional
appliances and have fewer problems in relation to speech
when compared with adolescent patients (McNamara
and Brudon, 1993). As parental authority tends to
decrease as patients reach adolescence, this could
potentially reduce patient compliance with the appliance
(Lund and Sandler, 1998).
4. If some degree of improvement can be achieved at an
early age, reducing the risk of upper incisor trauma, then
treatment can be justifi ed (Koroluck et al., 2003).
Conclusions
This study evaluated the soft tissue facial profi le changes in
38 subjects with Class II division 1 malocclusions, resulting
from normal growth and a phase of TB functional appliance
therapy, over a period of 12 months. The most notable
changes were:
1. A signifi cant improvement in facial profi le in the treated
group compared with the control group, with a reduction
in facial convexity.
2. Evidence of upper lip retraction and anterior displacement
of soft tissue pogonion.
3. Upper incisor retroclination in the treated patients, with
‘fl attening’ of the upper lip profi le.
Figure 5 Mean skeletal changes at the end of the study period for the
control and treated groups.
Figure 6 Mean dental changes at the end of the study period for the
control and treated groups.
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PROFILE AND FUNCTIONAL THERAPY
Address for correspondence
Dr Ione Helena Vieira Portella Brunharo
Rua Almirante Tamandaré 59/501
Flamengo
Rio de Janeiro
Brazil CEP: 22221–060
E-mail: cquintao@artnet.com.br
Acknowledgement
We would like to thank Professor Malcolm Jones, Dean,
Dental School, University of Wales College of Medicine,
Cardiff, U.K., for giving us access to the records of
subjects treated with twin block functional appliances,
which made it possible for us to develop a research
strategy in this fi eld at the Dental School, State University
of Rio de Janeiro.
References
Baccetti T, Franchi L, Toth L R, McNamara Jr J A 2000 Treatment timing
for Twin-Block therapy. American Journal of Orthodontics and
Dentofacial Orthopedics 118: 159–170
Broadbent H B 1931 A new X-ray technique and its application to
orthodontia. Angle Orthodontist 1: 45–66
Brunharo I P, Quintão C A 2001 O aparelho funcional Twin Block –
confecção laboratorial e aplicação clínica. Revista Brasileira de
Odontologia 58: 373–377
Burstone C J 1959 Integumental contour and extension patterns. Angle
Orthodontist 29: 93–104
Clark W J 1988 The Twin Block technique. A functional orthopedic
appliance system. American Journal of Orthodontics and Dentofacial
Orthopedics 93: 1–18
Clark W J 1995 Twin Block functional therapy. Applications in dentofacial
orthopaedics Mosby-Wolf, Turin, pp. 28–79
Chen J Y, Will L A, Niederman R 2002 Analysis of effi cacy of functional
appliances on mandibular growth. American Journal of Orthodontics
and Dentofacial Orthopedics 122: 470–476
Ferreira F V 1998 Ortodontia – Diagnóstico e planejamento clínico. Artes
médicas, São Paulo, pp. 187–224
Gianelly A A 1995 One-phase versus two-phase treatment. American
Journal of Orthodontics and Dentofacial Orthopedics 108: 556–559
Holdaway R A 1983 A soft-tissue cephalometric analysis and its use in orthodontic
treatment planning. Part I. American Journal of Orthodontics 84: 1–28
Holdaway R A 1984 A soft-tissue cephalometric analysis and its use in
orthodontic treatment planning. Part II. American Journal of Orthodontics
85: 279–293
Koroluck L D, Tulloch J F C, Phillps C 2003 Incisor trauma and early
treatment for Class II division 1 malocclusion. American Journal of
Orthodontics and Dentofacial Orthopedics 123: 117–126
Lund D L, Sandler P J 1998 The effects of Twin-Blocks: a prospective
controlled study. American Journal of Orthodontics and Dentofacial
Orthopedics 113: 104–110
McNamara Jr J A, Brudon N L 1993 Orthodontic and orthopedic treatment
in the mixed dentition. Needham Press, Ann Arbor
Mills C, McCulloch K 1998 Treatment effects of the Twin-Block appliance:
a cephalometric study. American Journal of Orthodontics and Dentofacial
Orthopedics 114: 15–24
Morris D O, Illing H M, Lee R T 1998 A prospective evaluation of Bass,
Bionator and Twin Block appliances. Part II – the soft tissues. European
Journal of Orthodontics 20: 663–684
Pancherz H 1979 Treatment of Class II malocclusion by jumping the bite
with the Herbst appliance. A cephalometric investigation. American
Journal of Orthodontics 76: 423–442
Pancherz H 1981 The effect of continuous bite jumping on the dentofacial
complex: a follow-up study after Herbst appliance treatment of Class II
malocclusion. European Journal of Orthodontics 3: 49–60
Pangrazio-Kubersh V 1985 Facial changes resulting from different
treatments in identical twins. Journal of Clinical Orthodontics
19: 356–361
Rabie A B M, She T T, Hägg U 2003 Functional appliance therapy
accelerates and enhances condylar growth. American Journal of
Orthodontics and Dentofacial Orthopedics 123: 40–48
Rains M D, Nanda R 1982 Soft-tissue changes associated with maxillary
incisor retraction. American Journal of Orthodontics 81: 481–488
Ricketts R M 1960 A foundation for cephalometric communication.
American Journal of Orthodontics 46: 330–357
Ricketts R M 1961 Cephalometric analysis and synthesis. Angle
orthodontist 31: 141–156
Riedel R A 1957 An analysis of dentofacial relationships. American Journal
of Orthodontics 43: 103–119
Roos N 1977 Soft-tissue profi le changes in Class II treatment. American
Journal of Orthodontics 72: 165–175
Shaw W C 1981 The infl uence of children’s dentofacial appearance on
their social attractiveness as judged by peers and lay adults. American
Journal of Orthodontics 79: 399–415
Steiner C 1953 Cephlometrics for you and me. American Journal of
Orthodontics 39: 729–755
Steiner C 1960 The use of cephalometrics as an aid to planning and
assessing orthodontic treatment. American Journal of Orthodontics
46: 721–735
Subtelny J D 1959 A longitudinal study of soft tissue facial structures and
their profi le characteristics, defi ned in relation to underlying skeletal
structures. American Journal of Orthodontics 45: 481–507
Subtelny J D 1961 The soft tissue profi le, growth and treatment changes.
American Journal of Orthodontics 31: 105–122
Toth L R, McNamara Jr J A 1999 Treatment effects produced by the Twin-
Block appliance and the FR-2 appliance of Fränkel compared with an
untreated Class II sample. American Journal of Orthodontics and
Dentofacial Orthopedics 116: 597–609
Trenouth M J 2000 Cephalometric evaluation of the Twin Block appliance
in the treatment of Class II division 1 malocclusion with matched
normative growth data. American Journal of Orthodontics and
Dentofacial Orthopedics 117: 55–59
Tulloch J F C, Phillips C, Proffi t W R 1998 Benefi t of early Class II treat -
ment: progress report of a two-phase randomised clinical trial. American
Journal of Orthodontics and Dentofacial Orthopedics 113: 62–72
Tung A W, Kiyak H A 1998 Psychological infl uences on the timing of
orthodontic treatment. American Journal of Orthodontics and Dentofacial
Orthopedics 113: 29–39
Vargervik K, Harvold E P 1985 Response to activator treatment in Class II
malocclusions. American Journal of Orthodontics 88: 242–251
Ward D M 1994 Angle Class II, division 1 malocclusion. American Journal
of Orthodontics and Dentofacial Orthopedics 106: 428–433
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