orthodontic bracket debonding

1. DEBONDING
BY DR TONY PIOUS

2. INTRODUCTION
 In orthodontic field its often necessary to break an adhesive
bond between two dental structures which includes procedures
such as the removing of orthodontic bands or brackets from the
teeth at the completion of treatment.
 Typically, orthodontic brackets are removed by mechanical
devices with application of force.
 There are many types of devices used for bracket removal, such
as pliers, mechanical arms etc.
 Orthodontic tool and method for fracturing the bond between
two dental structures should be quick and should not cause
significant trauma to the patient.

4.  Buonocore (1955): Demonstrated the increased adhesion of
attachments to tooth surface by conditioning the enamel
surface with 85% phosphoric acid for 30 seconds.
 Sadler (1958): Attempts to cement orthodontic attachments
directly to enamel without etching have been recorded. Sadler
tested nine materials (four dental cements, one rubber base
cement, two metal adhesives and two general purpose
adhesives) but these were all unsuccessful.
 Bowen (1962) developed a new resin system, Bisphenol-A-
Glycidyl dimethacrylate commonly known as BIS-GMA and is
often referred to as “Bowen’s Resin”.

5.  Newman (1965) was the first to bond orthodontic
attachments to teeth by means of an epoxy resin. He used a
mixture consisting of equal parts of low molecular weight
epoxy liquid and a high molecular weight solid epoxy with a
polyamide curing agent.
 Cueto (1966), his experiment was done to see if it was feasible
to attach a bracket directly to tooth enamel without the use
of orthodontic bands. The adhesive consisted of a liquid
monomer, methyl-2-cyanoacrylate, and a silicate filler.
 Mitchel (1967) had failures with an epoxy resin but described
a successful, although limited, clinical trial using black copper
cement and gold direct attachments.

6.  Buonocore et al (1968) showed that enhanced bonding to
acid conditioned surfaces were due to the presence of “prism
like” tags and also observed poor bonding with
unconditioned enamel surfaces.
 Smith (1968) introduced Zinc polyacrylate and bracket
bonding with cement was reported.
 Miura et al (1971) experimented with a new catalyst (a
modified trialkyl borane) and introduced orthomite. This
proved to be particularly successful for bonding plastic
brackets and for enhanced adhesion in the presence of
moisture.

7.  Retief (1973) described the importance of preconditioning with
50% phosphoric acid.
 Reynolds (1975) reported that a maximum tensile bond strength
of 5.9 to 7.9 Mpa would be a adequate to resist treatment forces
but added that, in vitro tensile strength levels of 4.9 Mpa have
proved clinically acceptable.
 Keizer et al (1976) evaluated direct bonding adhesives for
orthodontic metal brackets. Their study showed large standard
deviation of bond strength giving rise to speculation on reliability.

8.  Zachrisson (1978) stated that the objective of bonding was to get
as good as mechanical as possible between enamel and
adhesive and evenly distributed etching pattern with marked
surface roughness, but little actual loss of enamel is most desirable
to achieve mechanical interlock.
 Tavas et al (1979) introduced the concept of light activated
composites. They demonstrated that the bond strength of brackets
bonded with this was comparable with two chemically cured
adhesives.
Although important improvements in bonding have been
made in the last 30 years, the requirements of an ideal bonding
system are quite similar to those indicated by Buonocore.
Apparently, the future has a sound background in the past.

9. THE OBJECTIVES OF DEBONDING
 to remove the attachment and all the adhesive resin from the
tooth and restore the surface as closely as possible to its
pretreatment condition without inducing iatrogenic damage.
To obtain these objectives, a correct technique is of
fundamental importance.
Debonding may be unnecessarily time consuming and
damaging to the enamel if performed with improper technique
or in a careless manner.

10.  Debonding is discussed as follows:
• Clinical procedure
• Influence of different debonding instruments on surface
enamel
• Amount of enamel lost in debonding
• Enamel tearouts
• Enamel cracks
• Adhesive remanant wear
• Reversal of decalcifications

11. CLINICAL PROCEDURES
 Bracket removal
 Removal of residual adhesives

12. Bracket Removal
DEBONDING STEEL BRACKETS
 Several different procedures for debracketing with pliers
are available.
 An original method was to place the tips of a twin-beaked
pliers against the mesial and distal edges of the bonding
base and cut the brackets off between the tooth and the
base.

13.  A gentler technique is to squeeze the bracket wings
mesiodistaly and lift the bracket off with a peel force. This is
particularly useful on brittle, mobile, or endodontically
treated teeth.

14. The recommended technique
 Use of Debonding pliers: Recommended technique in which
the chisel shaped beaks are placed as close to the base of
the bracket as possible and a peeling type force is applied.
 Because metal brackets are ductile, this force is transmitted to
the adhesive bond, breaking it

15.  Lift-off Debonding Instrument: This a design of pliers in which a
tensile force is placed on the adhesive bond through a wire loop
hooked over the bracket tie wings, pulling the wings of the
bracket directly away from the tooth surface.
 This method distorts the brackets the least and is preferred if
recycling is a consideration.

16.  REMOVING BONDED BEGG BRACKET
 James n, here the walls of the vertical slot are squeezed
together.
 This action causes the base of the bracket to peel away from
the bonding material, lifting the edges of the base and
breaking the adhesive bond.
 The bracket and base then can be peeled off the tooth and
any adhesive remaining on the tooth surface can be gently
sanded and polished.
 A plier with a sturdy tip should be used for this technique, to
avoid breakage. The technique works best on minibased (3 –
mm width) brackets. If the base is wider or curved then ‘base –
squeezing” is very effective.

17.  LINGUAL DEBONDING

18. DEBONDING CERAMIC BRACKETS
- First generation ceramic brackets depended on silane coating
to ensure adhesion.
- The silane coupling led to excessively high bond strengths and
a resultant damage to the enamel at the time of debonding.
This problem has been solved in second generation by
incorporating a polycarbonate base or base can be sprayed
with atomized glass.
This ensured that at the time of debonding the failure
occurred at the bracket adhesive interphase.

19.  Ceramic brackets will not flex when squeezed with debonding pliers. The
preferred mechanical debonding is to lift the brackets off with peripheral
force application, much the same as for steel brackets.
 Several tie-wings may still fracture, which in practice requires grinding away
the rest of the bracket. Cutting the brackets off with gradual pressure from
the tips of twin-beaked pliers oriented mesiodistally close to the bracket-
adhesive interface is not recommended because it might introduce
horizontal enamel cracks.

20.  Vukovich ME etal (AJO 1991) Low – speed grinding of ceramic
brackets with no watercoolant cause permanent damage or
necrosis of dental pulps. Therefore water cooling of the
grinding sites is necessary.
 Bishara SE etal (AJO1997) More recent ceramic brackets have
a mechanical lock base and a vertical slot, which will split the
bracket by squeezing. Seperation is at the bracket adhesive
interface, with little risk of enamel fracture.

21. THERMAL DEBONDING
 Norman R. Gorback suggested that removal of ceramic brackets
can be painful and harmful for the patient, and difficult to remove
by the orthodontist. The use of heat makes bracket removal efficient
and painless, although extreme care is required to avoid touching
the teeth with a heated instrument.
Procedure:
 Tips of the utility plier are heated in the micro torch for ten seconds.
 The bracket is gripped with the heated plier.
 A light rotational force is applied after ten seconds.
 If the bracket does not snap off easily the procedure is repeated
after heating the plier for 15 seconds.

22. LASER DEBONDING
 Since the early 1990s, laser have been used experimentally for
debonding ceramic brackets.
 Mechanism of laser debonding (Tocchio et al AJO 1993 )
Laser energy can degrade the adhesive resin by three
methods :
1. Thermal softening
2. Thermal ablation
3. Photoablation

23.  Thermal softening occurs when the laser heats the bonding
agent until it softens. Clinically, this results in the bracket’s
surrendering to gravity and sliding off the tooth surface.
 Thermal ablation occurs when heating is fast enough to raise
the temperature of the resin into its vaporization range.
 Photoablation It occurs when very high – energy laser light
interacts with the adhesive material.

24. Time span for debonding with lasers
 The super CO2 laser products have high energy pulses
over a short time. The normal CO2 laser is made of continuos
waves with millisecond – duration pulses.
 Obata et al (Eur J 1999) reported that the super – pulse CO2
laser took less time for debonding than did the normal – pulse
laser (less than 4 seconds).

25.  Effects on the pulp
When laser radiation is applied to a ceramic bracket, energy is
absorbed and converted into heat.
This heat is then free to propagate by conduction to the base of the
bracket to soften the adhesive.
There is also potential for this heat to propagate to the tooth
structure and eventually lead to pulp damage.
 Obata (1995) reported that there was less increase in pulp cavity
temperature compared with bracket surface temperature.
Furthermore, lased and nonlased tooth pulps showed no histological
difference.
 Ma et al ( AJO 1997) showed that there is a linear relationship
between lasing time and an increase in intrapulpal temperature. A
mean intrapulpal temperature increase of
0.91º C after 1 second of lasing
1.74º C after 2 seconds
2.67ºC after 3 seconds

26.  Obata (1995) reported that there was less increase in pulp cavity
temperature compared with bracket surface temperature.
Furthermore, lased and nonlased tooth pulps showed no histological
difference.
 Ma et al ( AJO 1997) showed that there is a linear relationship
between lasing time and an increase in intrapulpal temperature. A
mean intrapulpal temperature increase of
0.91º C after 1 second of lasing
1.74º C after 2 seconds
2.67ºC after 3 seconds

27.  Time lag between lasing and debonding
 Abdul – kader and Ibrahim(1999) reported that
significantly higher force was required for debonding ceramic
brackets when 1 minute elapsed after laser exposure
compared with debonding immediately after laser exposure.
Therefore, debonding ceramic brackets one by
one immediately after exposure, before the adhesive resin
material resolidifies, requires less debonding force.

28. According to comprehensive review done on Laser debonding
of ceramic brackets by Ezz Azzeh and Paul J. Feldon (AJO
2003) they concluded that:
 The time spent to debond ceramic brackets is less when using
lasers.
 Debonding forces are significantly reduced with lasers.
 The risk of enamel damage and bracket fracture is significantly
reduced with lasers.
 The CO2 super – pulse laser is superior to normal pulse CO2
and YAG lasers.

29.  The use of monocrystalline brackets is suggested over
polycrystalline brackets.
 Ceramic brackets should be irradiated and debonded one by
one immediately after laser exposure.
 The risk of pulpal damage is significantly reduced if the
following are used:
 Super – pulse CO2 laser at 2 W for less than 4 seconds.
 CO2 laser for 3 seconds at 3 W.
 CO2 laser ( normal pulse ) at 18 W for 2 seconds.

30. REMOVAL OF RESIDUAL ADHESIVE
 Because of the color similarity between present
adhesives and enamel, complete removal of all
remaining adhesive is not easily achieved.
 Many patients may be left with incomplete resin
removal, which is not acceptable.
 Abrasive wear of present bonding resins is limited
and remnants are likely to become unesthetically
discolored with time.

31.  The removal of excess adhesive may be accomplished by
1. Scraping with a very sharp band or bond-removing pliers or with
scaler.
2. Using a suitable bur and contra –angle.
-- Dome shaped TC bur
-- Ultrafine diamond bur
-- White stone finishing bur
Although the first method is fast and frequently successful on curved
teeth it is less useful on flat anterior teeth. Also, a risk exists of creating
significant scratch marks.

32. The preferred alternative is to use a suitable dome tapered TC
bur in a contra-angle handpiece.
Clinical experience and laboratory studies indicate that
approximately 30,000 rpm is optimal for rapid adhesive
removal without enamel damage.
Light painting movements of the bur should be used so as not
to scratch the enamel. Water cooling should not be employed
when the last remnants are removed because water lessens
the contrast with enamel.
When all adhesive has been removed, the tooth surface
may be polished with pumice.

34. Adhesive remnant index (ARI)
-Artun
Used to evaluate the amount of adhesive left on
the tooth after debonding.
Score 0 : No adhesive left on the tooth
Score 1 : Less than half of the adhesive left
Score 2 : More than half of the adhesive left
Score 3 : All adhesive left on the tooth, with
distinct impression of the bracket mesh.

35. Presence of perichymata and imbrications.
Change in microstructure of enamel surface with age.
Gradual wear of enamel with age
0-2 µm per year
Characteristics of normal enamel

36. INFLUENCE ON ENAMEL BY DIFFERENT
DEBONDING INSTRUMENTS
Zachrisson and Artun were able to compare different
instruments commonly used in debonding procedures and
rank their degrees of surface marking on young permanent
teeth.
 The study demonstrated that
1. diamond instruments were unacceptable; even
fine diamond burs produced coarse scratches and gave a
deeply rough appearance.
2. medium sandpaper disks and a green rubber
wheel produced similar scratches that could not be polished
away

37.  3. fine sandpaper disks produced several marked and some
even deeper scratches and a surface appearance largely
resembling that of adult teeth.
 4. plain cut and spiral fluted TC burs operated at about 25,000
rpm were the only instruments that provided the satisfactory
surface appearance.
 5.none of the instruments tested left the virgin tooth surface
with its perikymata intact.
The clinical implication of the study is that TC burs
produced the finest scratch pattern with the least enamel loss
and are superior in their ability to reach difficult areas-pits,
fissures,, and along the gingival margin

38. AMOUNT OF ENAMEL LOST IN
DEBONDING
 10 to 25 μm.
 Pus and Way(AJO 1980) found a high-speed bur and green
rubber wheel removes approximately 20μm and a low-
speed TC bur removes around 10μm of enamel.
 Van Waes etal(1997) recently confirmed observations of a
more limited loss of enamel when TC burs are used
cautiously. They found an average enamel loss of only 7.4
μm and concluded that minimal enamel damage is
associated with careful use of a TC bur for removal of
residual composite.

39. ENAMEL TEAROUTS
 Redd TB(Jco1991) suggested localized enamel tearouts
have been reported to occur associated with bonding and
debonding both metal and ceramic brackets.
They may be related to the type of filler particles in
the adhesive resin used for bonding and to the location of
bond breakage.
When comparisons were made between tooth
surface appearances after debonding metal brackets
attached with either macrofilled (10 to 30μm) or microfilled
(0.2 to 0.3μm) adhesives, a difference occurred when the
resin was scrapped off with pliers.

40. On debonding the small fillers reinforce the adhesive tags.
The macrofillers, on the other hand, create a more natural
breakup-point in the enamel-adhesive interface. Similarly,
with unfilled resins there is no natural breakpoint.
 The clinical implications is
1. To use brackets that have mechanical retention
and debonding instruments and techniques that primarily
leave all or the majority of composite on the tooth.
To avoid scraping away adhesive remnants with
hand instrument.

41. ENAMEL CRACKS
 Zachrisson BU et al (AJO 1980) The prevalance of cracks, their
distribution per tooth, their location on the tooth surface and
the type were described;
 1. Vertical cracks are common, but great individual variation.

42. 2. Few horizontal and oblique cracks are observed normally.
3. No significant difference exists between the three groups
with regard to prevalance and location of cracks.
4. The most notable cracks are on the maxillary central incisors
and canines.

43.  The clinical implication of these findings
1. observes several distinct enamel cracks on the patients
teeth after debonding, particularly on teeth other than
maxillary canines and central incisors
2. detects cracks in horizontal direction, this is an
indication that the bonding or debonding technique used may
need improvement.
With ceramic brackets, the risk for creating enamel cracks
is greater than for metal brackets. The lack of ductility may
generate stress build-up in the adhesive-enamel interface that
may produce enamel cracks at debonding.

44. ADHESIVE REMNANT WEAR
 Adhesive has been found on the tooth surface, even after
attempts to remove it with mechanical instruments.
 Because of color resemblance to the teeth, particularly when
wet, residual adhesive may easily remain undetected.
 Brobakken and Zachrisson (AJO 1981)
Abrasive wear depends on the size, type and amount
of reinforcing fillers in the adhesive. At the time of debonding,
varying amounts of adhesive were purposely left on the teeth
assumed to be the most exposed to tooth brushing forces.
Only thin films of residual adhesive showed any reduction in
size.

45.  Gwinnett and Ceen (AJO 1978) reported that small remanants
of unfilled sealant did not predispose to plaque accumulation
and did begin to wear away with time. However, this finding
can not automatically be transferred to different types of filled
adhesives, some of which have much greater wear resistance
and accumulate plaque more readily.
 Brobakken and Zachrissons( AJO 1981) findings showed that
residual filled adhesive will quickly disappear by itself after
debonding; it appears irresponsible to leave large
accumulations of adhesive.

46. REVERSAL OF DECALCIFICATION
 White spots or areas of demineralization are carious lesions of
varying extent.
 The general conclusion was that individual teeth, banded or
bonded, may exhibit significantly more white spot formation
than untreated control teeth.
 In a multibonded technique Gorelick et al (AJO 1982) found
that 50% of the patients experienced an increase in whitespots.
 The highest incidence was in the maxillary incisors, particularly
the laterals.
 This obvious degree of iatrogenic damage suggests the need
for preventive programs using fluoride associated with fixed
appliance orthodontic treatment.

47.  Zachrisson BU (AJO 1975) suggested daily rinsing with dilute
(0.05%) sodium fluoride solution throughout the periods of
treatment and retention, plus regular use of a fluoride
dentifrice, is recommended as a routine procedure for all
orthodontic patients.
Artun and Thylstrup(1986) after debonding, arrest of further
demineralization, and a gradual regression of the lesion at the
clinical level takes place primarily because of surface abrasion
with some redeposition of minerals.

48.  Ogaard et al (AJO 1981) observed that remineralization of
surface softened enamel and subsurface lesions are
completely different processes.
The surface – softened lesions remineralize faster and
more completely than subsurface lesions which remineralize
extremely slowly, probably because of lesion arrest by
widespread use of fluoride.
Visible white spots that develop during orthodontic
therapy should therefore not treated with concentrated
fluoride agents immediately after debonding because this
procedure will arrest the lesions and prevent complete repair.

49.  At present it seems advisable to recommend a period of 2 to 3
months of good oral hygiene but without fluoride
supplementation associated with the debonding session. This
should reduce the clinical visibility of the white spots.
More fluoride may tend to precipitate calcium
phosphate onto the enamel surface and block the surface
pores. This limits remineralization to the superficial part of the
lesion, and the optical appearance of the white spot is not
reduced.

50. Microabrasion
 Done when remineralizing capacity of oral fluids is exhausted
and white spots established.
 Microabrasion: A gel prepared from 18% HCl, pumice and
glycerine is applied professionally with a modified toothbrush tip
for 3-5 mins; followed by rinsing.
This is effective for removing white spots and brownyellow
enamel discolorations.
 In case of more extensive mineral loss, grinding with diamond
burs or composite restorations may be required

51. White spot lesions After micro- abrations

52. CONCLUSION
 Orthodontic bonding has found to be more practical, and
beneficial than the circumferential bonding for many reasons.
Successful bonding in orthodontics requires careful
attention to three components of the system: the tooth surface
and its preparation, the design of the attachment base, and the
bonding material itself.
The future of bonding is promising. Product
development in terms of adhesives, brackets, and technical
details is continually occurring at a rapid rate. It is necessary for
the orthodontist to update and stay oriented.