Damon system in orthodontics. self ligating brackets in orthodontics

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Damon system
Collected by
Safa Basiouny Alawy
MSc, PhD Orthodontics
Lecturer of Orthodontics, Faculty of
Dentistry, Tanta University

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Contents:
1-Selfligating brackets; advantage and disadvantage
2-Self ligating brackets vs conventionally ligated brackets
3-The Damon Philosophy
4-Damon Bracket Design
5-Treatment Planning
6-Bracket Selection
7-Bracket Positioning
8-Treatment Phases, Archwire Selection, and Archwire
Sequencing
9- Archwire Stops
10-Retention

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Introduction:
-One of the more innovative products used are self-ligating braces. One
of the most popular self-ligating treatments is the Damon Braces System
and it is used all over the world. Damon braces are friction-free, which
enables them to provide comfortable tooth adjustment and straightening –
an aspect that is a great advantage compared to other orthodontics.
-Self ligating brackets have a built-in mechanism of holding the wire in
the slot instead of elastomeric or steel ligature
-The mechanism of holding the wire in the slot is either:
• A built-in lid/cover which can slide over the slot
• A clip
Advantages of self ligating brackets :
1-Ensure full engagement of archwire
2-Exhibit low friction between bracket and archwire
3-Quick and easy to use
4-Permit high friction when desired
5-Permit easy attachment of elastic chain
6-Assist good oral hygiene
7-Comfortable to the patient
8-Shorter ttt time
9-Decrease chairside time
10-Longer appointment intervals
11-Precise control of tooth translation

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Disadvantages:
1-Bulk (larger size)
2-High cost
 Self ligating brackets vs conventionally ligated brackets
Self ligated Conventionally ligated
Force level Permit use of lighter forces Require heavier force level
Force delivery Light initial force High initial force
friction Very low high
Risk of injury Reduced increased
instrumentation Fewer instrument during archwire
change
Many instrument required
Ligation Movable outer wall (cover or clip) Stst or elastomeric ligature
Ligation stability Retain original form Lose initial shape and tightness
Oral hygiene Easy to clean Difficult to clean, food trap
Chairside time Reduced increased
Treatment time Reduced increased

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 The Damon Philosophy
-The Damon philosophy is based on the principle of using just enough
force to initiate tooth movement—the threshold force i.e. low enough to
prevent occluding the blood vessels in the periodontal membrane to allow
the cells and the necessary biochemical messengers to be transported to
the site where bone resorption and apposition will occur and thus permit
tooth movement.
-A passive self-ligation mechanism has the lowest frictional resistance of
any ligation system. Thus the forces generated by the archwire are
transmitted directly to the teeth and supporting structures without
absorption or transformation by the ligature system.
Compared with conventional preadjusted edgewise appliances, it is
suggested that the use of passive self-ligation results in a significant
reduction in the:
● Use of anchorage devices because the frictional resistance generated by
ligatures is not present.
● Use of intraoral expansion auxiliaries such as quadhelices or W-springs
because the force of the archwire is not transformed or absorbed by the
ligatures and the necessary expansion can be achieved by the force of the
archwires.
● Need for extractions to facilitate orthodontic mechanics because
alignment is not hindered by frictional resistance from ligatures and can
therefore largely be achieved with small diameter copper nickel titanium
archwires. Tooth alignment therefore places minimal stress on the
periodontium as it occurs and so the possibility of iatrogenic damage to
the periodontium is reduced.

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In addition, a passive self-ligation system provides three key features:
● Very low levels of static and dynamic friction, Rigid ligation due to the
positive closure of the slot by the gate or slide
● Control of tooth position because there is an edgewise slot of adequate
width and depth. This allows extended intervals between treatment visits,
particularly in the early stages of treatment, a reduced number of visits
during a course of treatment, and shortened treatment times.
 Bracket Design
The bracket design of the Damon bracket has had the following
characteristics since its introduction as the Damon SL bracket:
1. A passive self-ligating design with conventional tie wings
2. A self-ligating gate, that opens to allow operator to see into slot.
As the bracket has evolved, the following features have changed:
1. The bracket has become smaller, with a lower profile and more
rounded contours resulting in a bracket that is more comfortable
for the patient.
2. the gate mechanism has become more reliable, and simpler to open
and close.
3. The D3 MX bracket has a vertical auxiliary slot.

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 Treatment Planning
Treatment planning involves five separate areas:
1-The Face
Treatment planning should take into account:
● The individual’s facial pattern and appearance, and
● The likely growth, maturation, and aging of the patient’s face including
the influence of genetic inheritance on their future facial appearance.
2-The Soft Tissues
-soft tissue behavior has been a significant factor in the development of
the malocclusion.
-This includes consideration of lip position and lip posture, tongue
behavior, muscle tone, and mode of breathing.
3-Dental Factors
Dental factors include:
• Space analysis,
• Arch width analysis
• The inclination of labial and buccal segment teeth.
4-Cephalometry
-Cephalometry remains an important tool for the orthodontist.
5-Oral Health
Patients with good oral health, excellent oral hygiene, and a normal
gingival biotype seem to obtain better orthodontic results than those with
compromised oral health.

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 Bracket Selection
The Damon System provides several torque options for incisor and
cuspid teeth and these are shown in Table 1. In general, the torque
selected in each bracket should be designed to over-correct tooth position.
A-High Torque Brackets
Indications:
used on upper incisors are as follows:
1. Extraction cases where treatment mechanics may excessively
retrocline the upper incisors;
2. Class II Division 1 malocclusions where treatment mechanics may
excessively retrocline the upper incisors; and
3. Class II Division 2 malocclusions.
used on upper cuspids are as follows:
1. First premolar extraction cases; and
2. Cases where the crowns of the upper cuspids are palatally tipped.
B-Standard Torque Brackets
Standard torque brackets are used where the inclination of the teeth is
satisfactory before treatment and the treatment mechanics will not
adversely affect the inclinations during treatment.
C-Low Torque Brackets
Indications:
used on upper incisors are as follows:
1. Excessively proclined upper incisors;

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2. Isolated upper incisors with palatally positioned roots (eg, upper
lateral incisor in the palate);
3. Malocclusions where treatment mechanics may result in excessive
upper incisor proclination;
4. Moderate and severe upper arch crowding; and
5. Anterior open bite cases with proclined incisors.
used on lower incisors are as follows:
1. Cases where it is necessary to control the proclination of lower
incisors, eg; extreme lower labial segment crowding, cases using
Class II elastics, and fixed Class II correctors attached to the
brackets, buccal tubes, or archwires;
2. Lingually placed lower incisors.
 Bracket Positioning
Bracket positioning follows the principles suggested by Andrews where
brackets are placed on the midpoint of the facial axis of the clinical
crown with the vertical bracket positioning key (eg, tie wings for D3 and
D3 MX brackets) parallel to this axis.
The following exceptions to this rule should be noted:
1. Lower cuspid brackets should be positioned 0.5 mm to 1 mm
mesial to the facial axis of the clinical crown to prevent the mesial
edge of the cuspid tucking behind the distal part of the lower lateral
incisor.
2. For deep bite cases, cuspid and incisor brackets should be
progressively placed slightly more incisally in both arches to aid
bite opening.

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3. For open bite cases, cuspid and incisor brackets should be placed
progressively slightly more gingivally in both arches to aid bite
closure.
4. Where teeth have to undergo significant translation, over
angulation of the brackets to exaggerate the root movement in the
desired direction will ensure adequate root movement. Examples :
opening of space for restorative implants, and closure of large
spaces such as moving lateral incisors into central incisor spaces.
5. Where teeth have incisal edge damage or are substituting for
other teeth, position the brackets to obtain the correct gingival
emergence profile and adjust the subsequent incisal edge problem
restoratively.
N.B. Brackets are not inverted to change the torque values as this may
make the gates more vulnerable to inadvertent opening, and rarely
generates enough torque to completely correct the problem. Instead,
choose a bracket with a torque value that will exaggerate the tooth
movement required (such as a low torque bracket for a palatally placed
upper lateral incisor). This solves the first problem, but in most cases,
additional torque will need to be placed in the archwire to obtain ideal
root position.
 Treatment Phases, Archwire Selection, and Archwire
Sequencing
Phase 1: Light Round High Technology Wires
-This phase of treatment uses 0.013_, 0.014_, or 0.016_ copper nickel
titanium archwires.
-The aims of this phase of treatment are to:
1. Obtain tooth alignment;

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2. Level the arches (excluding second molars). Second molars,
although bonded from the start of treatment, are not engaged by the
initial archwire until the second phase of treatment to prevent the
archwire being dislodged from the second molar tubes. The
intertube span between first molar and second molar is too large to
reliably support small-diameter nickel titanium archwires;
3. correct all anterior rotations and partially correct posterior
rotations;
4. Initiate arch development by using light enough forces to allow the
soft tissues to influence arch shape.
-This phase of treatment normally lasts 10 to 20weeks and appointment
intervals are at 8-10 weeks.
Phase 2: High Technology Rectangular Wires
-The second molars are normally engaged by the first archwires in this
phase except in patients with anterior open bites.
-This phase of treatment normally uses:
1. 0.014×0.025_ followed by 0.018×0.025_ copper nickel titanium
wires.
2. In cases that are well aligned at the start of treatment, these two
archwires can occasionally be replaced by a single
0.016×0.025copper nickel titanium wire.
3. Where incisor intrusion is required, 0.017×0.025or 0.019×0.025
copper nickel titanium archwires with preformed curves or reverse
curves of Spee can be used in this stage.
4. Additional torque can also be applied at this stage with the use of
0.019×0.025copper nickel titanium archwire preformed with 20°
of torque anteriorly.

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-The use of a wire with a 0.025 first order dimension is critical to obtain
tooth alignment by almost completely filling the 0.027_ slot depth of a
Damon bracket.
-The aims of this stage of treatment are to:
1. Fully correct all rotations and obtain full alignment of all teeth,
2. Consolidate any anterior space and maintain tooth contact,
3. Initiate torque control,
4. Initiate bite opening, and
5. Continue arch development.
-The duration of this phase of treatment is 20 to 30 weeks. The first
archwire is left in place for 8 to 10 weeks and the second for 4 to 6
weeks.
Phase 3: Major Mechanics
-The archwires used in this phase are 0.019×0.025_ preposted stainless
steel archwires.
- Many buccal segment crossbites will have corrected spontaneously by
this stage, particularly when the crossbite has not included the second
molars.
Where buccal segment crossbites persist, the use of a
0.016×0.025preposted stainless steel archwire in the arch where some
buccal or lingual tipping is desired, together with the use of a 3/16
(110 g) cross elastic, will assist crossbite correction.
-The aims of this phase of treatment are to:
1. Maintain the archform developed in the first two phases,
2. Finish torque control,

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3. Consolidate posterior space, and
4. Completely correct anteroposterior, buccolingual, and vertical
relationships.
-This phase of treatment lasts 8 to 10 weeks with appointments at 10-
weekly intervals.
-Where Class II or Class III elastics are being used, buccal segment
correction occurs more quickly if the molar distal to those to which the
elastic is placed are temporarily not included in the archwire.
Phase 4: Finishing and Detailing
-The stainless steel archwires may be continued in this phase.
-some detailed adjustments to individual teeth may require 0.019×0.025_
ß-titanium archwires
- Settling elastics may be used to develop a well-interdigitated occlusion.
 Archwire Stops
-Passive self-ligating brackets have extremely low levels of friction
between archwire and bracket Archwires are free to swivel to
mesiodistally and, if allowed to do so, cause “wire pokes” distal to the
terminal buccal attachments irritation to the buccal mucosa.
-Stops could be made of composite, soft split stainless steel tube, or
stainless steel tube placed over the archwire before insertion.
-Many high technology archwires now come with two stops preloaded on
to the archwires

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-the following recommendations for the use of stops are given:
1- To stop the archwire swiveling, stops are placed either side of a
bracket or at either end of an interbracket span.
2- Stops should be placed on a section of the archwire where little
movement of the archwire relative to the bracket is expected to
occur. Thus stops should be placed as far as possible from
crowded, displaced, or rotated teeth.
3- Where crowding is bilateral, stops should be placed anterior to the
crowding.
4- Stops should be placed where they are unobtrusive and not easily
seen. This normally means in the lower incisor region and in the
upper second premolar region.
Advantage of the arch wire stops:
1- help to identify the archwire once it is removed from the mouth.
2- stabilized archwire to prevent irritation to the buccal mucosa.
3- used to prevent tooth movement. Examples of this are as follows:
● Placement of the stops distal to the cuspids maintains consolidation of
the anterior segment.
● Placement of stops at either end of an interbracket span can maintain
space for an unerupted or prosthetic tooth.
● Placement of stops immediately mesial to upper second molars in first
molar extraction cases will maintain arch length to allow the resolution of
anterior crowding.
N.B. Stops are not required on preposted archwires as the posts act as
stops

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 Retention
-Retention is normally with a fixed solid 0.026_ stainless steel wire
retainer from the lingual surface of lower cuspid to lower cuspid. The
ends of the wire are flattened, contoured to maximize retention.
-In the upper arch, a braided retainer wire is bonded to the palatal
surfaces of the four upper incisors ensuring that it does not interfere with
the lower incisors.
-Upper and lower vacuum formed retainers are used in addition on a
nighttime-only basis.
-For patients who have had correction of a Class II skeletal pattern, a
Damon splint and tongue trainer is used to maintain Class II correction
over the long term.

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References:
1-Birnie D. The Damon Passive Self-Ligating Appliance System.
Seminars in Orthodontics. 2008;14: 19-35
2- Damon D, Bagden AM. Damon system the work book.