Orthotown January/February 2022 - 15

interference with mesiodistal movement
of teeth or groups of teeth, and low failure
rates when compared with interradicular
miniscrews. This allows the use of miniscrews
with larger diameter and length, and
allows simultaneous movement of the entire
dentition. This makes them suitable for a
wide range of orthodontic movements that
require an effective and safe anchorage
system, thereby expanding the horizons
of treatment options.1
Case selection for placement
of extraradicular screws
Extraradicular screws may be employed
in patients requiring maximum anchorage
for tooth movement such as protraction,
retraction, intrusion, extrusion, uprighting,
segmental or full-arch therapy, and
asymmetric tooth movement. Though it
can be used in the treatment of various
malocclusions, in my practice I limit the
use to distalization of entire maxillary or
mandibular dentition cases, especially for
subjects who have relapsed and have already
had their premolars previously extracted. It
may also be a good method to use in patients
who refuse to have therapeutic premolar
extractions performed.
Diagnosis and treatment plan
A 24-year-old patient came to the office
complaining about incompetent lips and
protruding teeth and jaws. A missing lower
right first molar was noticed during clinical
examination, as well as a Class III molar
and canine relationship on the left and a
Class I canine relationship on the right. The
lower midline was moved to the right by
2 mm. The patient had a steep mandibular
plane on a Class III skeletal base, as seen
on radiographs. Root canal therapy was
performed on tooth #21. On #36, there
was a significant decay. The existence of a
mesially inclined #38 with proclined upper
incisors was noted (Fig. 1).
Extraction of #14, #24 and #34 was
proposed. The upper and lower canine-tocanine
segments would then be retracted
into the available extraction spaces using
interradicular implants placed between
the upper and lower second bicuspids and
first molars.
Fig. 2: Whole-arch distalization of the maxillary and mandibular arches using
infrazygomatic crest and mandibular buccal shelf miniscrews, respectively.
This strategy was offered to the patient,
but he declined because of aesthetic concerns;
he worried about the bicuspid extraction
spaces being visible for several months.
Because of this, it was decided to extract the
third molars and insert four extraradicular
miniscrews (two IZC and two BS) in an
attempt to distalize the entire maxillary
and mandibular dentition at the same time.
Treatment progress
Upper and lower arches were bonded
with 0.022-inch MBT prescription brackets.
A sequence of NiTi wires, varying in size
from 0.014 inch to 0.016 inch to 0.018-by0.025
inch, was used to level and align the
arches. After the upper and lower arches
were perfectly aligned, teeth #18, #28 and
#38 were extracted and two IZC and two
BS implants were placed to begin whole-arch
distalization. A powerchain was extended
from the implant head to hooks inserted
distal to the lateral incisor brackets on a
0.019-by-0.025-inch stainless steel archwire
for whole-arch distalization (Fig. 2).
A force of 350 g per side was applied.
Because the miniscrews are clear off the
roots of the dentition, it is possible to achieve
an uninhibited mesiodistal movement
of the whole arch (Fig. 3). The rate of
distalization was approximately 0.5 mm
per month for both the arches, which is
slower because of the increased resistance
offered by many teeth.
Fig. 3: Midtreatment radiographs illustrate the placement of
extraradicular screws clear off the roots of the dentition.
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