3. Aims and objectives
Aims
-Philosophy!
-History of TADs
-Classification
-Clinical consideration
Objectives
-Discuss key design features
-Be familiar with some of the current products on the
market
4. Introduction
• Anchorage is defined as the prevention of unwanted
tooth movement. Profitt 2008
• Traditionally this was provided by anchor sites
within the mouth (intraoral anchorage) or from
outside the mouth (extraoral anchorage). Intraoral
anchor sites include teeth or other oral structures.
Extraoral anchorage is achieved by using headgear,
or facemasks.
• Another method of reinforcing anchorage is the use
of bone anchorage devices.
5. History
• Gainsforth and Higley first suggested
the use of metallic screws as anchors
back in 1945
• They studied effectiveness of vitallium
screws and stainless steel wires in the
mandibles of dogs to retract the
maxillary canine.
Vitallium is a trademark for an alloy of 65% cobalt, 30% chromium, 5%
molybdenum, and other substances. The alloy is used in dentistry and
artificial joints, because of its resistance to corrosion.
6. History
• Linkow(1969)-First reported a patient
treatment with the use of Osseo-
integrated implant for both restorative and
orthodontic purpose.
• Creekmore and Eklund (1983)- used
surgical vitallium bone screw just bellow
the anterior nasal spine to treat deep
overbite and it was 1stclinical report on the
use of TAD.
7. History
• Kanomi (1997)-first reported the clinical
use of mini-implants for orthodontic
anchorage.
• He implanted in the alveolar bone
between the root apices of mandibular
incisors and did intrusion of mandibular
incisors.
• Costa and colleagues in 1998 described
a screw with a special bracket-like head
for orthodontic use
8. History
Since then, various types of bone anchorage devices
(BAD’s) have been introduced in the market.
How effective? Numerous high quality evidence to support
effectiveness
Jambi et al 2014 Cochrane review: …..more effective than
conventional…. 15 studies, surgical anchorage vs conventional
anchorage Surgical more effective in reinforcing anchorage by 1.68mm
Alharbi et al 2018 ….13.5 % failure rate, systematic review, 46
papers
Hong et al 2016….highest success in the maxilla, 8mm or longer,
1.4mm or wider in 20 years old
9. Classification
1. According to the shape and size:
I) Conical (Cylindrical)
a) Miniscrew Implants
b) Palatal Implants
c) Prosthodontic Implants
II) Mini plate Implants
III) Disc Implants (Onplants)
2. According to Implant bone contact:
I) Osteointegrated
II) Non-osteointegrated
3. According to the application:
I ) Used only for orthodontic purposes. (Orthodontic Implants) or TAD
(temporary anchorage devices)
II ) Used for prosthodontic and
orthodontic purposes.
11. Endosseous
-These Osseo-integrated are modified form
of conventional dental implants.
-Success: 86-100% Odman et al 1991; Trisi
et al 2002
-Placed in palate,retromolar area,area of
absent or missing teeth.
-can withstand more force than
mechanically retentive implants.
Osseointegration, surface coating titanium with
calcium phosphate, calcium and titanium ions bond
13. Surgical miniplates
1.Modified or even conventional L or T
shaped surgical titanium mini plates
2.Placed in thick cortex similar to -zygomatic
region -buccal cortex of mandible.
3.Use-en mass distalization of lower arch in
class-3,maxillary intrusion of buccal
segment in openbite,en-mass maxillary
molar distalization
14. Miniscrews
• Derive their retention by mechanical means
only. Osseo-integration is not desired (to
enable easy removal)
• Some animal studies have shown that up to
58% of the screws can unintentionally osseo-
integrate (10–58%) ! Melsen and costa, 2000
15. Design features
Basic parts:
1-Head (to which attachments are
applied),
2-Collar (connects the core with the
head and provides a stop once it
encounters bone),
3-Core (part of the miniscrew which
lies within bone),
4-Thread (can be self-tapping or self-
drilling).
16. Considerations for selecting a
miniscrew
• Primary factors such as:
-material
-length
-diameter
• Secondary factors include
-head design
-platform
-soft tissue
-site of placement
-insertion technique
-loading forces
-type of tooth movement
17. Material
• Most miniscrews and other BADs are made of either
pure titanium or titanium alloy
• Some manufacturers use surgical stainless steel. Leone
mini implant system® , Bio Materials Korea® (ACR
series, Mplant and CAPlant)
• Titanium has proven properties of biocompatibility, is
lightweight, has excellent resistance to stress, fracture
and corrosion and is widely used.
• Pure titanium however has less fatigue strength than
titanium alloys. Spider screw anchorage system®
from HDC Italy, TOMAS system®
• Miniscrews are manufactured with a smooth
endosseous surface.
18. Titanium vs titanium alloy
• A titanium alloy, titanium-6 aluminum-4
vanadium, is used to overcome this
disadvantage.
• Clinically, the insertion technique is the
main difference between the two materials.
• Pure titanium= Pre-drilling is usually required
especially in high bone density sites.
• Vector TAS® , Ortho Easy®, Infinitas®, Neo-
Anchor Plus®
19. Endosseous
length
• Body part of the miniscrew
that lies within bone and
beneath soft tissues
• Ranges from 5 to 15 mm
• Location of adjacent
anatomical structures
(dental roots, nerves and
blood vessels)
• Bone depth
• Maxilla vs mandible
20. Endosseous length
Maxilla is composed more of cancellous bone, the
length of the implant should be longer and thinner
in contrast to miniscrews used in the mandible.
If the cortical bone is >1 mm in thickness, usually a
6 mm long miniscrew is adequate for primary
stability.
However, if the cortical bone is <1 mm thick, 8 mm
miniscrews are recommended for primary stability.
21. Endosseous length
Crismani et.al. 2010
….8 mm miniscrews were associated with 22%
higher success than 6 mm ones…supported by
Hong et al 2016
….minimum 8 mm length and 1.2 mm diameter
achieved good stability…
-Overall success rate= 83%
Maxilla=87%
Mand=80%
-Alharbi et al 2018, length not a significant factor!
22. Diameter
• Refers to the widest part of
miniscrew body
• Ranges from 1.2 to 2.3 mm
• Diameter site, material and
method of insertion of the
miniscrew.
• 1.3 mm =interradicularly.
• 1.3-1.5 mm= alveolar process.
• 2mm= In the retromolar region.
• <1.2mm higher failure rates.
• >2mm damage to roots.
23. Diameter
-Miyawaki et al 2003
concluded that their 1-mm thick screw performed
significantly worse than those with diameters of 1.5
and 2.3 mm.
-Wiechmann et al 2007 reported worse results for
1.1-mm thick screws than for 1.6-mm ones.
-Crismani et al 2010 1.2 mm or greater diameter
had good success rates (>70 %)
24. Head
• An ideal head design should be compatible with
the current edgewise bracket system
• Numerous head designs=grooves, ball ends,
tunnels, buttons and slots to aid the attachment
of auxiliary appliances such as ligature wires,
elastic thread and elastomeric chains
• One piece vs two piece design
25. The ACR CAPlantTM from
Bio Materials Korea®.The IMTECTM cope ortho-implant
system from 3M Unitek®.
27. Transmucosal
neck /collar
• The transmucosal neck=
emerges through the soft
tissue superficial to the
cortical plate
• Purpose of adequate
transmucosal neck design is
to prevent gingival irritation
from the attached auxiliaries
and minimise gingival
overgrowth.
• 1-2 mm
• Greater mechanical stability
• Almost all the manufacturers
incorporate the platform
design in their miniscrews,
with the exception of the
MAS system.
29. Site of placement
• As a general rule,
miniscrews
inserted in D1 and
D2 regions,
achieve greater
stability and those
inserted in D4
regions are
associated with
higher failure
rates
• Insertion at 30–
40° to the dental
axis allows the
insertion of a
longer screw in
the available bone
depth
33. Distribution of the inferior alveolar nerve as it travels through the
mandibular canal.
34. Insertion technique
1-self-drilling
2-self-tapping (pre-drilling)= initial
placement of pilot hole in the bone
• The ideal diameter of pilot hole should
be around 80% of the external
diameter of the screw
• Miniscrew diameter 0.2 to 0.5 mm
>pilot hole
• Pre-drillingless than 1.3 mm
diameter, made of commercially pure
titanium and the bone at the insertion
site is thick.
• Self-drilling more than 1.3 mm
diameter, made of a titanium alloy and
the bone at the insertion site is thin.
35. Insertion
technique
Self drilling:
Problems generated from accidental drilling can be
avoided (overenlargement of the pilot hole,
overheating from high drill speeds and drilling into
dental roots) (Mah and Bergstrand, 2005).
36. Loading force
-Loaded immediately or after a healing period of 2
weeks (Melsen and Costa, 2000; Liou et al., 2004).
-If loaded immediately25 g should be applied
(Cornelis et al., 2007).
-After 2 weeks higher forces can be applied
(Ohashi et al., 2006).
-Can withstand forces ranging between 50– 600 g
(Ohashi et al.,2006; Miyawaki et al., 2003; Costa et
al., 1998).
-Upper threshold is 200 g !
-Currently there is no agreement in the literature
on the threshold limit (Cornelis et al., 2007).
37. complications
Insertion
• Damage to dental roots (Kadioglu et al., 2008; Rossouw
and Buschang, 2009).
• Damage to PDL
• Akylosis
• Loss of vitality
• Relevant anatomy!, max. sinus, greater palatine neve,
inferior alveolar nerve
• Bending/fracture
Loading
• Poor OH, mucosal irritation
• Peri-implantitis
• Soft tissue hypertrophy
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45. Conclusion
• Since their introduction, orthodontic miniscrews have
shifted the paradigm of anchorage
• In this article, we reviewed the development of
miniscrews and outlined the general design features
as well as specific design features of current
miniscrews in the market.
• Practical examples can be found elsewhere as we
aimed in this article to improve the readers’ theoretical
and clinical knowledge and focused on one type of bone
anchorage only, the miniscrews.
• Finally, practitioners are encouraged to attend
appropriate training courses and to restrict themselves
to limited range of screws that suit their particular case
load.
