Introduction
Anchorage control is one of the most difficult
treatment goals since the early years of orthodontics. Arguably, proper teeth
position cannot be established unless the option of anchorage control is
considered. Even though dentists pursue the absolute anchorage idea, history
proves that it is hard to achieve. Existing literary works reveal numerous
attempts to eliminate the deleterious
effects of moving specific teeth while maintaining the position of others.
However, this has been difficult to achieve using tooth borne anchorage. Often,
unwanted tooth movement is seen invariably in teeth serving as anchor units,
hence the need for auxiliary anchorage sources such as palatal buttons, lingual
arches, and headgears. While devices such as these significantly improve the
levels of anchorage, absolute control over dental movements is not allowed. Besides, patient compliance is
required in all of these methods, but cannot be expected. If the patient does
not comply, anchorage control will be lost, leading to frustration and
compromised treatment results.
In the modern times, severe implant forms are applied
to establish complete anchorage and eliminate instances of unwanted tooth
movement. Restorative implants are approximately 8-10mm long and 3mm in
diameter. When the implants are placed in the arches and allowed to heal, they
can act as a prosthetic replacement of
teeth in addition to orthodontic anchorage. Still, their use is limited by the
healing times, arch space, and strict location.
Additionally, onplants (2mm thickness x 10mm width) and
palatal implants (3.3mm x 5mm) have been applied for orthodontic anchorage.
Unlike restorative implants, doctors can use palatal implants in individuals
that do not need the replacement of a missing tooth. However, their placement
demands significant invasive surgery. Even worse, mechanical placement of these
implants is complicated as compared to the restorative type. Despite onplants being developed for absolute anchorage
without the need for bone preparation, they still require extended healing
times due to surgical interventions.
Given the setbacks of
restorative implants and onplants, orthodontists
worldwide are shifting their attention towards mini-screw implants (MSIs). They
are small (approximately 1.2 mm thickness and 8mm length) customized titanium
alloy screw serving as an anchor point on
the patient’s jaw. In most cases, orthodontists place MSI in areas such as
between the roots of molars and premolars, though they can also be fixed on
mouth’s roof. Furthermore, orthodontists only need to perform minimal surgical
procedures for removal or placement. In some situations, a local anesthetic
is required to numb the gum area before mini-screw implants can be inserted. Today,
orthodontists in the UK and across the
world use mini-implants to correct bite problems that otherwise demand orthognathic surgery. MSIs are less expensive
in comparison to onplants or restorative
implants. Considering these, it is clear that MSIs are gaining prominence as
dominance players in medicine, specifically in the realm of implant orthodontics.
Undoubtedly,
researchers have adequately documented the use of MSI in literature. However, a
consensus is yet to be attained regarding the positional stability of
mini-screw under immediate orthodontic load and operative delayed load. Further,
there is a literary gap on the rate of retraction between delayed loaded
implants and immediately loaded implants. Given that the use of MSIs is
relatively new in the field, the comparison of molar anchorage in immediate and
delayed loaded implants is yet to be determined. Therefore, this research aims
at bridging the existing gaps and to advance the existing knowledge on MSIs. Currently,
there is no report of 8mm long and 1.2 mm thick MSIs in the literature.
This study shall also
determine the biomechanical and clinical outcomes of orthodontic mini-screw
implants under different load time regimen of immediate, 2 weeks, and 4 weeks.
In addition, the researcher reviews and updates the success under delayed load
of 4 weeks and immediate load in 20 healthy adult individuals equally divided
into two groups. In fact, patients with
systemic disorders or compromised oral hygiene are
excluded from the study. In the first group, implants will be loaded as soon as
the placement is done while in the second group, the MSIs will be loaded postoperatively after 4 weeks. Female patients
and male subjects are be 16 and 18 years of age respectively.
This study is based on
the notion that mini-screw implants gain most of their retention capability
from cortical plate location. Naturally, cancellous bone is less dense than
cortical bone, hence a proposed theory that MSIs ought not to be longer or
thicker than the cortical plate. The
literary review contains an in-depth analysis of anchorage and its importance
to orthodontic tooth movement. An adequate
explanation of the importance of anchorage allows for a better understanding of
the use of MSIs for orthodontic anchorage. In light of this, the evolution of
implant anchorage is discussed. Subsequently, multiple studies that describe
the clinical results and use of MSIs is presented and exhaustively highlighted.
A discussion such as serves as an important outline of the work that has already been done and what remains to be
covered in the field of mini-screw implants.
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