TREATMENT EFFECTS
OF R-APPLIANCE IN VERTICAL GROWING PATIENTS-CASE SERIES
Figure 1. The R-appliance
1. ANB > 4°, SNB < 78°, overjet > 4 mm at the
initial lateral cephalograms;
2. Nonsyndromic or medically compromised
patients;
3. No previous surgical intervention;
4. No use of other appliances before or during
the period of functional treatment.
5. No skeletal asymmetry
6. Vertical growth pattern (GoGn-SN > 32°)
All the patients were treated with the
R-appliance (10, 12, 13) (Figures 1 and 2). The
patients were instructed to wear the appliances
full-time except for eating, contact sports and
tooth brushing.
The R-appliance is a tooth and tissue borne
appliance. It consists of buccal and lingual shields,
which are connected to each other through the
occlusal clearance during bite construction. These
shields are extended to the distal of the first
permanent molars and cover the buccal and lingual
regions and the depth of the vestibule. The lingual
shield should be fabricated with minimal undercut
relieve. The left and right lower lingual shields are
connected and reinforced with a heavy archwire
(1mm diameter) to withstand the load of muscular
activity. A heavy wire (1mm diameter), which acts
as a tongue bow, is positioned posterior to connect
the right and left acrylic parts on the palatal aspect
in order to reinforce the appliance. The labial
bow is constructed of 0.7 mm stainless steel wire
extended from canine to canine with vertical loops
in the canine region. In this group, the construction
bites were taken with the upper and lower anterior
teeth in an edge to edge occlusion with more than
4 mm of posterior clearance. In other words, the
thickness of the connection between buccal and
lingual shields would be more than 4 mm. Lateral
cephalograms of the patients were taken in
centric occlusion at the start (T1) and completion
(T2) of functional treatment. SNA, SNB, ANB,
Y-axis (angle between the line connecting Sella
to Gnathion and SN), GoGn-SN (angle between
SN and mandibular plane), Gonial angle (the
angle formed by the junction of the posterior
and lower borders of the lower jaw), Inclination
STOMA.EDUJ (2014) 1 (2)
Figure 2. The R-appliance in the mouth
angle (angle between perpendicular line
dropped from N-Se at N’ and palatal plane), 1
to SN (angle between long axis upper central
incisor and anterior cranial base), IMPA (angle
between the long axis of the lower central
incisor and mandibular plane), interincisal angle
(angle between upper and lower incisors), 1 to
NA (distance between maxillary central incisor
to N-A), ī to NB (distance between mandibular
central incisor to N-B), occlusal to SN (angle
between SN and occlusal plane), and Jarabak
index (the ratio between posterior and anterior
face heights; S–Go/N–Me) were measured on
pre and post treatment radiographs.
Two weeks after the first measurements, the
tracings and measurements were repeated by
one blinded dentist on 10 random cephalograms
at the beginning and end of the treatment. To
assess the reliability of the measurement, the
intraclass correlation coefficients were calculated
for each variable in the T1 and T2 cephalograms.
No significant differences were found between the
first and second measurements of those randomly
selected cephalograms.
Data were tested for normality and appropriate
statistical test were applied. Statistical significance
was set at P<0.05. The magnification factor of
the cephalograms was standardized at 8 per
cent. The Statistical Package for Social Sciences,
Version 20 (SPSS Inc. Chicago, Illinois, USA)
was used to analyze the data. Paired T-test was
used for evaluation of pre and post treatment
measurements if the distribution was normal;
otherwise, Wilcoxon test was used.
Results:
After 16 (SD 0.4) months of treatment paired
T-tests showed significant ANB decrease of 3.2°
(SD 1.6°) (P<0.001) and SNB increase of 3.3° (SD
1.5°) (P<0.001). IMPA significantly decreased from
101° (SD 7.2°) to 98° (SD 9.7°) (P<0.02). 1 to SN also
significantly decreased for 6.1° (SD 5.6°). Jarabak
index increased from 59.2% (SD 3.4%) to 61%
(SD 3.5%) (P<0.007). Before and after treatment
changes can be seen in table 1.
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