This document defines orthodontic anchorage (OA) and discusses its early understanding and assessment. It describes factors that influence anchorage demand and different classifications of OA. Theories of optimal force levels and differential anchorage are explained. Various methods to reinforce anchorage are outlined, including using compound anchorage units, anchor bends, tipping and uprighting teeth, extraoral anchorage, and musculature forces. The evidence for the differential force theory is discussed.

1. UNIVERSITY OF GLASGOW
Orthodontic Anchorage
Mohammed Almuzian
Personalnote
1/1/2013

2. Table of Contents
Definition................................................................................................................................. 2
Early and modern understanding of OA ..................................................................................... 2
Optimal force level in orthodontics ............................................................................................ 2
Assessment of the anchorage demand or factors that can contribute to OA loss............................. 4
A. Depending on how far the OA unit can move in response to the reactionary force (OA
burn) Nanda, 2009. ................................................................................................................... 5
B. According to the position or the source of the OA (Moyer, 1988) ........................................... 6
1. Extraoral OA................................................................................................................... 6
2. Intraoral OA.................................................................................................................... 6
I. Intramaxillary (originates from the same arch) can be subdivided into:................................ 6
A. Originating from teeth...................................................................................................... 6
B. Originating from soft tissue .............................................................................................. 6
C. Originating from bone...................................................................................................... 7
II. Intermaxillary (from the opposing arch) like ...................................................................... 7
Evidence for the differential force theory ................................................................................... 7
Methods to reinforce OA........................................................................................................... 7
Measuring OA:........................................................................................................................15
A. Cephalometric measures of OA........................................................................................15
B. Study model measurement...............................................................................................16
OA in three Planes...................................................................................................................16
1). Vertical Anchorage.............................................................................................................16
2). Lateral anchorage ...............................................................................................................16
Orthodontic bone anchorage.....................................................................................................17
Anchorage control during tooth levelling and aligning .....................Error! Bookmark not defined.
How to control anchorage in the leveling stage ................................Error! Bookmark not defined.

3. Orthodontic Anchorage
Definition
The word Anchorage means the northernmost city in Alaska in the
United States (officially called the Municipality of Anchorage) or it can
be defined at that portion of a harbour or area outside a harbour suitable
for anchoring or in which ships are permitted to anchor (Wikipedia
2013).
So it is better always to use the word orthodontic anchorage (OA) to
refer to the resistance to unwanted tooth movement (Profit, 2000) or
those sites that provide resistance to the reactive forces generated on
activation of any orthodontic appliance to control unwanted tooth
movement. (Mitchell, 2001)
OA loss or burn is associated with undesirable movement of the anchor
units during orthodontic treatment.
Early and modern understanding of OA
Early studies suggested that the rate of tooth movement was associated
with the magnitude of the force applied and the surface area of the root
of the tooth. Partly as a result of this philosophy, clinicians have
undertaken various steps in order to prevent the anchor teeth from
moving, also known as conserving anchorage. These include:
1. Light force: Using a light force sufficient to move the tooth, but not
large enough to move the anchor unit.
2. Rootsurface area of anchored teeth: Utilize teeth with maximum
root surface area as an anchor unites.
3. Number of anchored teeth: Involving as many teeth in the OA unit
as possible to distribute the force over a larger root surface area
4. Number of teeth to be moved: Only moving one tooth at a time per
quadrant
Optimal force level in orthodontics
Optimal force level in orthodontics defined as a mechanical input that
leads to maximum rate of tooth movement with minimal irreversible
damage to the root, periodontal ligament and alveolar bone. The theory
of optimum forces was proposed byStorcyand Smith in 1952.
Force threshold is defined as the minimum force to produce
movements. Classically, ideal forces in orthodontic tooth movement are
those that just overcome capillary blood pressure 20-25gm/cm3 as per
Schwartz (1932).
Quinn & Yoshikawa, 1985 mentioned four theories regarding force
magnitude:

4. 1. Hypothesis 1 shows a constant
relationship between rate of
movement and stress. The rate of
movement does not increase as the
stress level is increased. However no
studies supportthis theory.
2. Hypothesis 2 is more complex.
The relationship here calls for a
linear increase in the rate of tooth
movement as the stress increases.
Hypothesis 2 is difficult to disprove
because most studies used only two
force magnitudes and were unable to
describe the behaviour of the curve as the stress reached higher levels
(Johnston 1967).
3. Hypothesis 3 depicts a relationship in which increasing stress
causes the rate of movement to increase to a maximum. Once this
optimal level is reached, additional stress causes the rate of movement to
decline. This hypothesis was originally proposedbySmith and Storey
1952. The available literature suggests that hypothesis 3 may not be an
accurate representation of the data. This had been supported later by Lee
1995.
4. Hypothesis 4 is a compositeof some of the foregoing concepts.
Here the relationship of rate of movement and stress magnitude is linear
up to a point; after this point an increase in stress causes no appreciable
increase in tooth movement. This had been supported later by Owman-
Moll 1996 and King 1991. From the study of Samuel 1998 that
compared in his RCT between 100gm and 200gm NiTi spring and also
used the historical data from his previous study in 1993. Samuel in 1998
found that there is no difference between 150gm and 200gm but a
significant difference between the last two forces and 100gm. The
existing clinical data may best supportthe interpretation provided in
hypothesis 4.
However,
Pilon (1996), working on Beagle dogs, showed that the rate of tooth
movement and amount of OA loss were not significantly different for
forces from 50g to 200g. In some dogs, teeth moved quickly while in
others, teeth moved slowly, regardless of the forces used. The rate of
movement was highly correlated between right and left sides in each
dog, suggesting that inherent metabolic factors may be much more
important than force level in determining the rate of movement of the
teeth (including those in the OA unit). However, Pilon (1996) found that
rate of tooth movement was still related to rootsurface area, as the OA
units moved less than the teeth being moved. Therefore, there is some

5. scientific supportfor the differential force theory, but the exact extent of
its influence is unknown. Other studies have shown that similar
individual variation in orthodontic responseto applied force also appears
to occurin humans (Hixon 1969, Hixon 1970).
Ren et al. 2004 systematic review showed insufficient data to determine
whether there is a threshold of force below which tooth movement does
not occur. They also identified a wide range of forces (104–454 gm) over
which the maximum rate of movement could be achieved.
Assessmentofthe anchorage demand
A. Generalfactors
1. Age
2. Medicalcondition
3. Medication
4. Individual variation
5. Patient compliances
B.Treatment plan factors
1. Treatment aims: correction of molar relationship after extraction
require little anchorage than correction of sever OJ or crowding
2. Type of movement required, bodily movement require higher
anchorage demand than tipping movement.
3. Extraction pattern, the more posterior teeth extracted the more
anchorage demand will be.
C.Treatment mechanics factors
1. Appliance prescription: MBT less anchorage demand than Roth
and Andrews prescription
2. Appliance type, tip edge appliance required less anchorage
demand than SWA. URA is less anchorage demanding than FA.
3. Mechanotherapy: heavy force need more anchorage.
D.Intra-arch relationship
1. Involved arch: The maxillary arch is particularly susceptible to OA
loss. This is probably due to a combination of factors:
 Maxillary anterior teeth are bigger and wider.
 The upper anterior brackets have more tipping built into than the lower
anterior brackets.
 The upper incisors require more torque controland bodily movement
than the lower incisors, which only require distal tipping or uprighling.

6.  Mandibular bone is harder than cancelous maxillary bone. So that the
upper molars move mesially more easily than the lower molars.
2. Amount of crowding: sever crowding requires more anchorage
3. Locationof crowding, the more distance between anchor unit from
the irregular teeth to be align or retracted, the more anchorage demand.
4. Angulation of the teeth, distally angulated canines required higher
anchorage to align and retract them than upright or mesially inclined
canines.
5. Inclination of the teeth, palatally tipped upper incisor require
more anchorage to retract them than proclined one
E.Inter-arch relationship
1. Amount of OB
2. Amount of OJ
3. Amount of centreline problem
4. SkeletalrelationshipAP: camouflaging moderate to severe skeletal
relationship is more anchorage demanding than mild cases
5. Skeletal relationshipvertically, high angle cases require higher
anchorage demand because:
 Bone is less dense than bone of low angle case which favour teeth
movement and anchorage loss
 The direction of the occlusal plane favour the mesial movement of the
anchor teeth
 A weaker muscle fibres associated with high angle case produceless
occlusal interlocking than normal.
6. Occlusalinterlock
F.Factors relate to the anchorage unites
1. Rootsurface area of the anchorunits, incisors especially lower
incisors require less anchorage demand than canines and premolar.
2. Teethcondition& PD support, heavy restored, PD compromise
teeth or short rooted teeth provide less anchorage supportthan normal
teeth.
ClassificationofOA
A. Depending on how far the OA unit canmove in response to the
reactionaryforce (OA burn) Nanda, 2009.
1. Minimum 75% OA burn

7. 2. Moderate 50% OA burn.
3. Maximum 25% OA burn or if no movement of the OA unit is
permissible
B. According to the position or the source of the OA (Moyer,
1988)
1. ExtraoralOA
Like HG or facemask EOA.
2. Intraoral OA
I. Intramaxillary (originates from the same arch) canbe subdivided
into:
A. Originating from teeth
1. Simple OA (one tooth providing OA to other tooth)
2. Compound OA (group of teeth providing OA to one tooth or
smaller number of teeth). This theory is not fully proven, but indirect
evidence strongly suggests that the theory has substance. For example,
Saelens & DeSmit (1998) showed that greater mesial movement of the
molars and less resolution of anterior crowding occurred when second
premolars rather than first premolars are extracted. However, the
available data on the relationship between the applied force and the tooth
movement achieved has not yet confirm a clearer picture (Hixon 1969,
Hixon 1970, Quinn & Yoshikawa 1985).
3. Stationary OA (refers to the advantage that can be obtained by
putting bodily movement of one group of teeth against tipping of
another).
4. Differential anchorage:mean moving the teeth by tipping them
first then upright them to reduce the stress on the anchor teeth
5. Reciprocal It may be that equal movement of both the active and
reactive units is desirable, such as expansion or closing a midline
diastema, when OA is described as reciprocal. (Hixon, 1969)
6. Differential force theory: is a combination of Stationary and
Differential anchorage.
 The active units are allowed to tip by relying on the anchor units which
are hold by the effect of their bodily reaction.
 Then the active units are uprighted.
B. Originating from soft tissue
1. Lip bumper
2. Bone palatal vault like Nance and URA

8. C. Originating from bone
1. Skeletalorbone OA (implants/miniscrews/plates)
2. CorticalAnchorage
II. Intermaxillary (from the opposing arch) like
1. Myofunctional appliance
2. Intermaxillary elastic. the disadvantages ofthis are
Needpatient compliance
Molarextrusion
Proclinationof anterior segment
Difficulty with URA
Evidence for the differential force theory
A study by Pilon et al (1996) in beagle dogs showed that the rate of
tooth movement and the amount of anchorage loss were not significantly
different for forces ranging from 50 g to 200 g. Some dogs had teeth that
moved quickly and others moved slowly regardless of the force level.
The rate of movement was highly correlated between the left and right
sides for any dog and this suggests that inherent metabolic factors may
be much more important than force level in determining the rate of
movement of teeth including those in an anchorage unit. Anecdotal
clinical observation certainly suggests that human patients show similar
variation in orthodontic responseto applied force (Hixon, 1969 & 1970).
A Meta review by Ren et al (2003) referred to over 400 studies of
relevance and it is clear that the details of the relationship between force
applied and tooth movement remain insufficiently understood or
documented.
More recent study by Yee et al (2009) who measured canine retraction
and anchorage loss with a light (50 gm) and heavy (300 gm) forces over
a 12 week period. The 300 gm force produced significantly more
movement of both the canine and the anchorage unit and the percentage
of anchorage loss was significantly higher (62%) with the heavy force
than with the light force (55%). The size of that difference is certainly
not dramatic but does support the differential force theory.
Methods to reinforce OA
1. Compound OA: Include more teeth in the anchor unit.
2. Anchor bends (stationary anchorage):Bends made in the
archwire between the molar and premolar teeth at an angle of 30 to the
occlusal plane can prevent the molar tipping in reaction to a mesially
directed force thus increasing its OA potential. In the SWA it is called

9. The Tweed-Merrifield philosophy or bio-progressive theory. Tweed
described tipping the molars distally like a ‘’tent stakes’’.
3. Tipping and uprighting (Differential force theory):
TipEdge or Begg principle where the upper anterior teeth are allowed to
tip distally using the force of the intermaxillary class II elastic, but the
molar is prevented from moving forward by a ‘tipback bend’.
Additionally, the tipback bend helps to overcome the vertical extrusive
effect of the elastic on the anterior teeth.
However, it is not clear whether tipping and subsequently uprighting a
tooth consumes less OA than achieving the same result with bodily
movement. More recently, a good study by Shpack et al (2008), found
that bodily retraction of a canine consumes the same anchorage as
tipping followed by uprighting and incidentally, bodily retraction was
more rapid by an average of 38 days.
4. Extraoralorthodontic anchorage support(See the HG note):
Example HG or PHG which get its supportfrom a very stable skeletal
structure outside the mouth like cranium, occipital area and the chin.
Feldmann, 2009, RCT to measure the anchorage loss with Onplant (1),
TAD (2), EOT (3) & TPA (4). They found that after levelling/aligning
phase: the anchorage was stable in the group 1, 2 & 3 while group 4
showed 1.0 mm. But after space closure phase, the anchorage was stable
in the group 1 & 2 but group 3 & 4 showed 1.6 and 1.0 mm of mesial
drift of molars respectively. Feldmann, 2012, measured the patients’
perceptions in term of pain, discomfort, and jaw dysfunction with
Onplant (1), TAD (2), EOT (3) & TPA (4). The results confirm that
there were very few significant differences between patients’ perceptions
of skeletal and conventional anchorage systems during orthodontic
treatment
TADs or HG. Junqing in 2008 showed again a better result by TADs in
comparison with HG.
5. Musculature forces:for example
 Functionalappliance: It must be remembered that a reactionary
mesially directed force occurs in the mandible and the reactionary
distally directed force occurs in the maxilla during the use of the
functional appliance. This could lead to upper teeth distalization and
lower teeth mesialization. See the functional appliance note
The lip pumper: It mainly consists of a thick round stainless steel wire
that fit in the headgear tube of the molar band and stays away from the
labial surface of the incisor by the effect of the loop mesial to the
entrance to the molar tube. The acrylic pad is embedded in the anterior
part of the wire and act to actively displace the lip forward. The
reciprocal force of the displaced lip will be transferred to the molars via
the heavy wire and result in molar uprighting and distalisation. As a

10. consequenceof the change in the soft tissue equilibrium by the lip
pumper, there is a proclination in the incisors under the effect of tongue
as well as increase in the intercanine width (Cetlin & Ten Hoeve, 1983).
The forces are originated from the deliberately displaced lower lip by the
acrylic lip pad. However, the effects of lip bumper were described by
O'Donnell 1998, Bjeregaard 1990 & Nevant 1991 & include:
i. Molar distalization and tipping
ii. Reduce anterior crowding
iii. Incisor proclination and protrusion
iv. Increase intercanine and intermolar width and perimeter
6. Intermaxillary elastics:
This relies on using the opposingarch to provide OA to the other arch.
Care must be taken to realise that intermaxillary traction is an inefficient
method of spaceclosure and if prolonged can lead to excessive extrusion
and tipping of the anchor teeth.
 Sometime elastic can be used in conjunction with sliding jigs. This
was a mainstay of the original Tweed technique in which the force from
Class II elastics aid in pushing the upper molars distally via a sliding jig.
The force level is 250 gm per side is needed. In addition the class II
elastic help in correction of class II malocclusion by clockwise rotation
of the occlusal plane which can be compensated in growing patient. This
is why it should not be used for more than 6 months in adult patient
(Tweed, 1967)
7. Intraoral skeletalsystem:like the TADs, miniplates, implant &
Onplant. See the TADs note. By the way TADs considered type of
cortical bone anchorage
Feldmann and Bondemark 2008 in their RCT measured the anchorage
loss with Onplant (gp1), TADs (gp2), HG (gp3) & TPA (gp4). They
found anchorage loss only in gp4 after levelling/aligning phase
(approximately 1mm) but this had been increased to reach 2mm.
additionally, gp3 showed 1.6 mm of anchorage loss while the anchorage
was stable in the gp 1 & 2 from the start until the end of treatment.
Three years later, the same authors measured the difference patient
perception in the four groups in term of pain, discomfort, and jaw
dysfunction. They concluded a very few significant differences between
skeletal and conventional anchorage systems in term of patient
perceptions.
Sharma et al 2012. compared the anchorage loss with the use of TPAs
or TADs and found 2.5 mm of mesial movement of the U6s with the
former while the latter provided absolute anchorage

11. Junqing in 2008 showed again a better result by TADs in comparison
with HG for treatment of bialveolar dental protrusion.
Liu 2009 compared the use of TPA and TADs in he found that
better dental, skeletal and soft tissue changes could be achieved
by minicrew implants especially in hyperdivergent patients. Skeletal
anchorage should be routinely recommended in patients with bialveolar
dental protrusion.
Salma and Hajeer 2014 TAD better than TPA
8. Palatalvault: Example URA & Nance appliance which relies on
the bone and soft tissue anchorage
9. Corticalanchorage:
By the way TADs considered type of cortical bone anchorage
Rickets technique by intentionally bringing the buccalroots of the
anchor teeth into contact with the cortical plates of bone thus increasing
the OA value of such teeth. It should be appreciated that this process
should be carried out with great care and precision since overzealous
torque can produceroot resorption or in extreme cases cortical
perforation. (Brezniak & Wasserstein, 2008)
The transpalatal arch, qaudrihleix & the lingual arch. It also depends on
the idea of compound-cortical anchorage by increasing the number of
teeth in the OA system as well as cortical bone anchorage theory.
However there is a risk of root resorption (Brezniak & Wasserstein,
2008) See the TPA note.
Transpalatalarches uses to provide anchorage
Provision of transverse
anchorage
 TPAs can be used to improve arch width
stability when aligning palatally impacted
maxillary canine (Fleming, Sharma et al.
2010)
 In cleft palate, TPA has its application to
maintain the form of the expanded arch just
before alveolar bone grafting. (Harris and
Reynolds 1991)
 For almost the same application, TPAs act as
a retainer after RME
 after surgical expansion of the palate in order
to hold the osteotomies part together during
healing period. (Harris and Reynolds 1991).
 TPAs are used to counteract the buccal
tipping of the crown of the molars during
intrusion of the anterior teeth using

12. Segmented Burstone Arch Wires mechanics.
(Burstone 1966)
 For the same reason TPAis combined with
Class II bite correctors to counteract the
buccalforces applied by the (TFBC) Twin
ForceBite Corrector. (Rothenberg, Campbell
et al. 2004)
 As an adjunct to headgear (HG), TPAs are
used to reduce buccaltipping of the molar
and palatal cusp hanging the molar
distalization. (Baldini and Luder 1982)
However, a study by Wise et al. showed no
difference between the use of HG with or
without a TPA during molar distalization.
(Wise & Magness et al. 1994).
 Lastly, TPAs were used with palatally or
buccally placed TAD to controlmolar tipping
when posterior teeth are intruded to treat
anterior open bites. (Cousley 2010)
Provision of vertical
anchorage
 It had been showed that placing the TPA
4mm away from the palate might introduce
some intrusive effect by the tongue on the
molars which can help in correcting or
controlling the over eruption of maxillary
molars.(Goshgarian 1974).
Provision of
anterioposterior
anchorage
 Nance appliance can be used to provide
anchorage to distalize the molars such as the
Pendulum Appliance (Hilgers 1992), rapid
molar distalization (REF); the distal jet
(Carano, Testa et al. 1996, Carano, Testa et
al. 2002), Jones Jig (Jones and White 1992,
Paul, O'Brien et al. 2002, Patel, Janson et al.
2009) and the Lokar Distalising Appliance
(Lokar 1994, McSherry and Bradley 2000).
 In the same field, TPA can be used to
maintain molar position after
distalization.(Prakash, Tandur et al. 2011)
again TPA can be used to provide anchorage
during fixed appliance treatment through
bringing the roots of the upper molars in
contact with cortical bone (Cortical
anchorage).
 However, there are many studies that

13. compare the effectiveness of the TPA with
other methods. Zablocki & McNamara
(Zablocki, McNamara et al. 2008) concluded
that the mean anchor loss of 4.1 mm was seen
in association with the TPA and 4.5 mm in
control group.
 Feldmann & Bondemark (Feldmann and
Bondemark 2008) in their RCT measured the
anchorage loss with Onplant (gp1), TADs
(gp2), HG (gp3) & TPA (gp4). They found
anchorage loss only in gp4 after
levelling/aligning phase (approximately
1mm) but this had been increased to reach
2mm. additionally, gp3 showed 1.6 mm of
anchorage loss while the anchorage was
stable in the gp 1 & 2 from the start until the
end of treatment. Three years later, the same
authors measured the difference patient
perception in the four groups in term of pain,
discomfort, and jaw dysfunction. They
concluded a very few significant differences
between skeletal and conventional anchorage
systems in term of patient perceptions.
(Feldmann, List et al. 2012).
 A study comparing Nance and TPA
appliances, found that both appliances are
moderately effective in preserving anchorage
(anchorage loss of around 1mm over 6
months) and there is no difference in
anchorage supportbetween them but TPA
well tolerated by the patient. (Stivaros, Lowe
et al. 2010).
 Sharma et al. 2012 compared the anchorage
loss with the use of TPAs or TADs and found
2.5 mm of mesial movement of the U6s with
the former while the latter provided absolute
anchorage.
 Lastly an interest finite element simulation
study conducted by Kojima et al. (2008)
showed that TPA provides no anterioposterior
anchorage.(Kojima and Fukui 2008)

14. 10. Natural anchorage. Ankylosed teeth possessno periodontal
membrane and as such are not subject to the normal physiologic
responseto forces placed on the tooth and movement will be absolutely
resisted. Kokich in 1985 illustrated a casewhere he utilised two
deciduous canines, which he deliberately ankylosed by extraction
followed by reimplantation
11. Treatment planning steps to reinforce the OA
a. Extraction pattern: extraction of the teeth which close to the reactive
unit will reduce the OA demand.
b. Appliance prescription.
I. Standard edgewise less anchorage demanding.
SWA comparing to standard edgewise. Johnstonet al (1988) reported
that the use of the SWA cost0.8mm more OA (measured by the
Pitchfork method) in the maxilla when compared with Standard
Edgewise treatment. However, this may be explained by the fact that a
preadjusted appliance makes it less likely that a clinician will finish a
case with inadequately torqued upper incisors, and the slightly higher
OA requirement with the SWA therefore reflects the achievement of
more anchorage demanding occlusal goals.
II. Roth incisors are more OA demanding
III. Andrews canines are less OA demanding
IV. MBT less OA demand than Roth and Andrews system because:
 The wagon wheel effect: because increasing the incisor torque will cause
the mesial tip of ULS to reduce and this will reduce the anchorage
demands
 Reduced canine, premolar and molar tip compared to Roth
 Increased molar root torque buccally, increase anchorage by cortical
bone theory
 Reduce upper molar mesial tip reduced the OA demand
 Upper molar 10 degree offset, counteract the unwanted rotational
movement during spaceclosure in the upper arch and this might
strengthen the anchorage
V. Tip-Edge is less OA demanding than SW because of the relying on the
tip-uprighting principle.
SWA comparing to tipe-dgewise. Lotzof (1996) found that the TipEdge
appliance consumed less OA than the SWA during canine retraction
(~0.6mm less, over a 3 week observation period). However, the results
did not reach statistical significance due to the small sample size, and it
should also be noted that the canines retracted with the TipEdge
appliance were not fully uprighted in this study. Shpack, 2008 compare

15. retraction of the canine using tipedge bracket and regular bracket in split
mouth study found that canine retraction in the first group was longer
and the anchorage loss was same in both groups.
VI. Self-ligating bracket: it is suggested that becausethere is less friction
in the system, lighter forces can be used and that this will be ‘lighter’ on
anchorage.
12. Biomechanicalsteps to reinforce OA
a. Using light force that is not overload the OA units.
b. Lacebackand bendback which used with SWA
Robinsonin 1989, in a prospective study found a 2.47 mm difference
in the lower incisor anteroposterior position between cases treated with
or without lacebacks. In the laceback group there was a mean 1.0 mm
distal movement of the incisors and a mean 1.76 mm mesial movement
of the first molars (so the OA loss is 0.76mm). In contrast the non-
laceback group demonstrated a mean 1.47 mm proclination of the
incisors compared with a mean 1.53 mm forward movement of the
molars (so the OA loss is 3mm).
Usmani 2002, results showed that Lacebacks do not prevent ULS
proclination, they have no effect on molar position, the amount of ULS
proclination depend on the angulation of the canine and the laceback
makes no difference. So there is no benefit from laceback.
Irvin 2004, in first premolar extraction cases, the use of laceback
ligatures conveys no difference in the anteroposterior or vertical
position of the lower labial segment. Furthermore, the use of laceback
ligatures creates a statistically and clinically significant increase in the
loss of posterior anchorage
Sueri et al 2006 applied the MBT technique with extraction of the first
premolars to study the effectiveness of laceback ligatures on maxillary
canine retraction. Canine distalization was successfully achieved with
laceback ligatures. Canine and molar movements were significantly
smaller in laceback cases.
Fleming 2012 in their systematic review found that there is no
evidence to supportthe use of lacebacks for the control of the sagittal
position of the incisors during initial orthodontic alignment
c. Stopped arch and utilities. (It is a type of compound anchorage theory):
The use of stopped arch wires recruits OA from the posterior and
anterior teeth while sliding individual teeth along the archwire. Rajcich
& Sadowsky (1997) showed that retraction of canines with sliding
mechanics, where the molar is prevented from tipping or sliding mesially
by an auxiliary arch and tip-back bends, incurs very little OA loss.
d. Subdivision of desired movement

16.  Moving a single tooth at a time, rather than dividing the arch into more
equal segments can preserve anchorage. Forexample, in extraction
cases where OA is not at a premium, canines are usually retracted until
sufficient spaceexists to align the incisors, and the complete labial
segment is then retracted as a unit. According to the differential
anchorage theory, this would be expected to increase OA demand
compared with fully retracting the canines to a class I relationship and
then retracting the incisors. Therefore, if Enmasse retraction of the 6
anterior teeth is carried out, there must be a good reason to choosethis
more OA demanding option. Generally, the advantages of Enmasse
retraction are simplicity, and avoiding the need to repeat stages of
treatment, such as realigning the teeth following sectional mechanics.
 Heo in 2007 showed no significant differences existed in the degree of
anchorage loss of the upper posterior teeth and the amount of retraction
of the upper anterior teeth associated with en masse retraction and two
step retraction of the anterior teeth. Again TianMin Xu 2010 fond no
difference between Enmasse and two stage retraction.
Measuring OA:
OA is assessed bycomparison over time of tooth position relative to a
non-tooth structure. The data is either
1. Cephalometric using
 LLS position in relation to N-Pog or NB or MP
 Pitchfork or Pancherz analysis
 Superimposition technique
2. Intraoral photograph
3. Study models by superimposing on the rugae area (Sandler 2014)
4. Direct Clinical assessment especially if one arch is left as a baseline.
A. Cephalometric measures of OA
1. Lower incisor AP position – a more labial position of the lower
incisors at the end of tooth movement is considered to represent OA loss.
Measures such as LiNPo or LiMn are used to assess this.
2. Pitchfork Analysis (Johnston 1996). Superimpositions on bony
structures – the reference structures are the maxilla and zygoma. This
analysis is used to measure AP movement of the upper and lower
incisors and molars. It provides a useful summary of the contributors to
AP effects of treatment, but no measurement of changes in incisor
inclination or canine angulation.
3. Pancherz : measure linear changes from perpendicular drawn from
sella to occlusal line (weakness is that it depend on max structure and OP
which is changeable)
4. Subjective analysis using superimposition technique such as
DeCosta’s line in the cranial base and Bjork’s stable structures in the
maxilla and mandible are used. Then the position of the anchor unit is

17. assessed subjectively. All reference structures have disadvantages, both
in principle and in terms of the practicalities of reliable identification and
measurement of landmarks.
B. Study model measurement
The use of palatal rugae as a reference for OA loss measurements has
been suggested, and is becoming more widely used with developments in
digital imaging, which assist the recording, enhancement and
measurement of study models.
Hoggan & Sadowsky(2001) concluded that rugae landmarks are as
reliable as cephalometric structures for superimposition, but the SD of
repeated measurements was +0.8mm, so changes of less than 1.6mm
using this method are unlikely to be statistically significant.
OA in three Planes
It is important to remember that orthodontic forces may be applied in a
sagittal (anterposterior), coronal (vertical) or lateral (horizontal)
direction. As such, consideration of the OA requirements must be
considered likewise in these directions.
1). Vertical Anchorage.
Consideration of vertical OA is important in the reduction of curve of
Spee (overbite) or in the treatment of anterior open bite.
Reduction of the curve of Spee can involve putting the resistance of
extrusion of the posterior teeth against the resistance of the intrusion of
the anterior teeth. In the clinical situation a degree of both occurs and a
type of reciprocal-compound OA could be said to exist. During the
levelling stage of treatment, extrusion or intrusion forces applied to
individual teeth would be counteracted by the OA values of a greater
number of teeth. To increase the efficiency of this type of tooth
movement it is advisable to band the second permanent molars. This is
classically thought to increase the OA value of the posterior segment
hence encouraging intrusion in the anterior segment. It may be
worthwhile considering in this case that extrusion of the second
permanent molar would have a greater effect on overbite than extrusion
of the first permanent molar as it is positioned more distally in the arch.
Anterior open bite: Intrusion of the posterior teeth can be made more
efficient by utilising intermaxillary traction with “box”elastics in the
anterior segments. This process helps withstand the intrusive effects of
the “reverse curve” imparted in the wire and can be considered a type of
intermaxillary compound anchorage. This process has found favour in
the technique of “Kim” mechanics.
2). Lateral anchorage
Consideration of horizontal OA is important in the treatment of
maxillary constriction resulting in crossbites. Sucha case where

18. equivalent groups of teeth are moved equivalently is a classic casein the
use of reciprocal anchorage. Occasionally the occasionis seen where
there may not be an equivalent number of teeth in crossbite on both sides
of the arch. In such cases it is important to incorporate a greater number
of teeth in the anchor unit than in the unit in which maximum tooth
movement is desired. This is achieved by the inclusion of palatal arms
into the respective side of the quadhelix.
Movement of palatally placed ectopic canines can be quite OA
demanding. OA is usually obtained by applying force to the canine when
the upper arch has been stabilised by a heavy gauge stainless steel
archwire or applying the horizontal force from the two maxillary molars
conjoined by a palatal arch.
Both these methods increase the OA value of the anchor units by
increasing its rootsurface area and by preventing tipping and rotation
Orthodontic bone anchorage
Please refer to the TAD note.