the tweed profile - The Charles H. Tweed International Foundation

RESULTS
VOLUMETRIC MEASURES
Palatal volume increased between T1 and T2 from
9.35 cm3 to 10.48 cm3 (10.78%) for group I and from
9.38 cm3 to 10.41 cm3 (9.89%) for group II. Airway
space volume included between lower first molars
perceived a reduction from 1.57 cm3 to 1.30 cm3
(-17.19%) for group I and from 1.84 cm3 to 1.33 cm3
(-27.71%) for group II.
SKELETAL MEASURES
Transverse skeletal diameter at the canine increased
from 3.59 cm to 3.66 cm for group I and from 3.82 cm
to 3.87 cm for group II. Transverse skeletal diameter
at the molar increased from 5.77 cm to 5.80 cm for
group I and from 5.17 cm to 5.73 cm for group II.
A decrease was recorded in mandibular alveolar bone
thickness: 1.46 cm - 1.40 cm (-1.0%) on average for
group I and 1.34 cm - 1.28 cm (-1.0%) on average for
group II.
Measures on sagittal slices revealed an increase in the
distance ANS-PNS equal to 0.09 cm (5.04 cm - 5.13
cm) for group I and equal to 0.17 cm (4.64 cm - 4.81
cm) for group II. Palatal vault height increased by
0.07 cm (1.40 cm-1.47 cm) for group I and by 0.09 cm
(1.82 cm-1.91 cm).
DENTAL MEASURES
Inclination of maxillary first molars increased to
2.13° (93.42° - 95.55°) on average for group I, 4.02°
(104.06° - 108.08°) on average for group II.
Mandibular first molars showed a reduction of
4.58° (100.38°- 95.78°) on average in group I, 1.77°
(101.99°- 100.29°) on average in group II.
Intercanine diameter at the apex showed an increase of
0.13 cm (2.48 cm – 2.61 cm) for group I and 0.10 cm
(2.82 cm – 2.93 cm) for group II. At tip variation was
0.36 cm (2.92 cm – 3.28 cm) for group I and 0.07 cm
(2.81 cm - 2.89 cm) for group II.
Intermolar diameter measured at the apex showed an
increase of 0.40 cm (3.04 cm - 3.44 cm) for group I
and 0.09 cm (3.08 cm - 3.17 cm) for group II. At the
crown variation was 0.40 cm (3.20 cm - 3.60 cm) for
group I and 0.25 cm (3.30 cm - 3.54 cm).
Sagittally, the distance between maxillary right central
incisor and PNS showed a variation of 0.05 cm (4.10
cm - 4.15 cm), 0.00 cm (4.20 cm - 4.20 cm), -0.03 cm
(4.79 cm - 4.77 cm) respectively for apex, CEJ and
crown for group I and 0.16 cm (3.59 cm - 3.76 cm),
0.31 cm (3.67 cm - 3.98 cm) and 0.43 cm (4.24 cm -
4.67 cm) for group II.
Sagittally, the distance between the maxillary right
molar and PNS increased by 0.11 cm (1.78 cm - 1.90
cm), 0.15 cm (1.25 cm - 1.40 cm), 0.06 cm (1.20 cm -
1.26 cm) respectively for the distovestibular root apex,
CEJ and distal cusp tip for group I and by 0.22 cm
(1.35 cm - 1.56 cm), 0.40 cm (0.78 cm -1.18 cm) and
0.40 cm (0.60 cm - 1.00 cm).
DISCUSSION
The aim of this research was to evaluate the tridimensional
effects of RME when employed for tranverse
maxillary deficiency correction; in particular, a comparison
of the effects of RME on permanent and RME
on deciduous teeth was done. The employment of
CBCTs allowed analysis of volumetric, skeletal and
dento-alveolar parameters.
The applicability of CBCTs in orthodontics has been
limited by high costs, the long attainment time (MRI)
and the high radiation dose. Nevertheless, in the last
few years, CBCT images are becoming more and more
common in clinical practice because of their ability
to visualize pathologies in three dimensions and their
evolution in terms of cost, access and decreased overall
effective absorbed doses of radiation 27 .
The accuracy of linear and volumetric measurements
obtained by CBCT have been tested by many authors,
such as Mischkowski et al. 28 , who used gutta-percha
markers and concluded that the CBCT device provides
satisfactory information about linear distances, and Lagravere
et al. 29 , who used titanium markers with a hollow
cone on a synthetic mandible and concluded that
volumetric renderings from the CBCT device produce
a 1:1 image-to-reality ratio.
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