Approximation and contact of the maxillary central incisor roots with the incisive canal after maximum retraction with temporary anchorage devices_ Report of 2 patients

Chung, Choi, and Kim 499
Fig 7. Pretreatment intraoral photographs and radiographs.
Table II. Cephalometric analysis of patient 2
Measurement Norm Pretreatment Posttreatment
Skeletal ( )
SNA 81.6 6 3.1 89.2 88.5
SNB 79.1 6 3.0 81.7 81.9
ANB 2.4 6 1.8 7.5 6.7
FMA 24.0 6 5.0 25.6 25.3
Dental ( )
IMPA 94.0 6 5.0 107.8 94.1
U1 to SN 106.0 6 5.0 113.9 96.3
Interincisal 126.0 6 7.0 105.1 137.7
angle
Soft tissue (mm)
Upper lip 1.0 6 2.0 4.3 1.1
E-plane
Lower lip
E-plane
1.0 6 2.0 5.3 0.7
possibility of maxillary incisor approximation, nearly in
contact with the incisive canal after maximum retraction.
The average width of the incisive canal in the axial
plane at the level of the apical third of the root is
reportedly about 3 to 5 mm, with a large variation
ranging from 1.1 to 6.7 mm. 4,5,17 Since the average
interroot distance between the maxillary central
incisors is about 3 to 4 mm, root touching or
approximation with the incisive canal, especially in
the mesiopalatal surface, can be speculated in certain
cases after maximum amounts of distal root
movement (Fig 1). 18,19 Variations in the morphology
of the incisive canal have been frequently reported
with 3D imaging, including deviation to 1 side,
widening or cystic changes, furcations, and so
on. 4,5,17 The incisive canal, in many circumstances, is
deviated toward the right central incisor, similar to
the situation of patient 1 (Figs 3 and 5, periapical
radiographs). 8 The 3D CBCT images also show the
root touching the incisive canal only in the right central
incisor. During treatment, changes in root parallelism
in cases of improper bracket positioning or addition
of root torque during retraction may also lead to root
convergence of the incisors, decreasing the interroot
distance. 20 Although the sagittal distance between
the incisor roots and the incisive canal is yet to be
determined, 3D evaluations during orthodontic diagnosis
and close monitoring of the incisor roots
throughout treatment would be advantageous in
American Journal of Orthodontics and Dentofacial Orthopedics September 2015 Vol 148 Issue 3