Bonding in orthodontics / online orthodontics courses

BONDING IN ORTHODONTICS– II
www.indiandentalacademy.com

CONTENTS
1. Evolution of bonding agents
2. Banding
3. Indirect bonding
4. Bonding to special surfaces
5. Other applications
6. Bond strength
7. Debonding
8. Decalcification &
Demineralizationwww.indiandentalacademy.com

Double Transfer Trays for Indirect Bonding
-JCO Jan, 2004
-Pablo Echarri, Tae-Woen Kim
 Indirect bonding
 Lingual orthodontics
 Transfer trays:
•Full arch
•Single-tooth categories

1. Full arch trays:
a. Opaque
b. Translucent
c. Thermoplastic
2. Single-tooth trays:
a. Hiro system
b. Kyung’s Individual Indirect Bonding
Trays
c. Kim’s Convertible Resin Core ready made
trays

•Triad light cure acrylic

Cast with finished single unit transfer trays

Finished double transfer tray made from
Xantopren and Optosil silicone
Procedure for Labial orthodontics

Advantages of the Double-Tray system
 Used with Slot Machine, CLASS, KIS system
 Reduced chairside time - simultaneous bonding
 Trays - easy to remove
 Excess removed before curing
 Progressive bonding-crowding, rotations
 Single unit trays - precise rebonding, with no
fear of tray distortion.

Rebonding
 Bracket removed from arch wire.
 Remnant adhesive on the bracket removed
with a TC bur.
 Bracket base - sandblasting.
 Tooth cleaned and Re-etched.
 Bracket rebonded.
 Bond strength comparable to that of new
brackets.

Recycling
 Goal - remove adhesive from bracket base
without damaging it nor cause any change in
the slot dimensions.
 Done by heat treatment (upto 450°c) and
electropolishing.
 Recycling of ceramic brackets by heating or
resilanating.

OTHERAPPLICATIONSOF BONDING IN
ORTHODONTICS
1. Bonded retainers
2. Space maintainer
3. Semi-permanent single
tooth replacements
4. Trauma fixation
5. Resin build-up

1. BONDED RETAINERS
 Invisible
 Reduced caries risk
 Compliance-free
 Stability
Types:
1. Mandibular canine-to-canine retainers
2. Direct contact splinting
3. Flexible spiral wire retainers

A. Mandibular canine-to-canine
retainers

DIRECT BONDING:
2-step procedure
1. Tacking
2. Adhesive bulk

INDIRECT BONDING:

B. Direct contact splinting

C. Flexible spiral wire retainers

D. Labial retainers

2. SPACE MAINTAINER
Artun & Marstrander – 0.032” spiral, utility design

3. SEMI-PERMANENT SINGLE TOOTH
REPLACEMENTS

4. TRAUMA FIXATION

5. RESIN BUILD-UPS FOR TOOTH SIZE
AND SHAPE PROBLEMS

BOND STRENGTH
“The bond between
enamel and orthodontic
bracket is unique”

It is intended to be strong yet temporary
 Required to be intact for at least 2 years
 Withstand orthodontic forces and forces of
occlusion
 Must be broken with minimum amount of
trauma - to tooth and patient

 Numerous adhesives and bracket configurations
 Bond testing – bonding potential of new systems
Goals of bond testing –
1. Measure force of debonding
2. Observe location of bond failure

1. Debonding force –
 Force on bracket during mastication – 40 to 120 N
 Newtons(N), pounds(lbs), kilograms(kg)
 Misleading – substantial differences in bonding
areas of brackets tested
 Bracket bases – different geometries

BOND STRENGTH:
 Force of debonding divided by area of bonded
interface
 MPa, kg/cm2
, psi
 Reynolds et al –optimum bond strength –
6 to 8 MPa
 Various factors affecting bond strength

2. Bond failure:
a. Adhesive failures – between cement and
tooth / cement and bracket
b. Cohesive failures – within
adhesive/tooth/bracket
 Combination of the two
 Type of failure – assessed by ARI

Adhesive remnant index (ARI)
-Artun & Bergland (AJO – 1984)
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.

EVALUATION OF BOND STRENGTH
In vitro In vivo
EXPERIMENTAL MODEL CLINICAL STUDIES
1. EXPERIMENTAL MODEL
 Mechanical testing machines
 2 types

a. SCREW-DRIVEN
- screws at both ends move crossheads

b. SERVOHYDRAULIC
- crossheads separated by hydraulic pistons
 Both used to test tension, compression,
bending, or torsion
 Specimen fixtures purchased/designed by
experimenter
 UNIVERSAL TESTING MACHINES

Instron Universal Testing Machine
Screw-driven, originally developed by Instron
Corporation, USA

Types of tests:
1. Clinical Simulation Model – tooth + bracket
 Clinically relevant
 Bond failure at both interfaces – weak link
cannot be identified

2. Isolated Interface Model
 Both interfaces studied separately
 Metal bracket – adhesive interface – bond failure
common

2. CLINICAL STUDIES
 Clinical bracket retention – FAILURE RATE
 No. of brackets that failed over the study
period by the no. of brackets bonded

Bracket failure rate affected by –
1. Age and sex of patient
2. Treatment mechanics
3. Operator
4. Tooth type
 Lack of standardized protocols for lab and
clinical testing

Intraoral aging of orthodontic materials : The
picture we miss and its clinical relevance
-AJO-DO 2005
-Eliades and Bourauel
 To analyze the effect of various aging variables
affecting the structure and properties of
polymeric and metallic orthodontic materials

 Clinical requirement of bond strength based on
1975 article by Reynolds – 6 to 8 MPa
 Cited more than 150 times in literature
 Not accurate –
1. Conjectural – based on vaguely assumed load
application during mechanotherapy
2. Does not account for stresses during mastication
of hard food / higher chewing velocity
3. Does not include aging of polymeric adhesive
and associated environment stress fatigue
phenomenon www.indiandentalacademy.com

CONCLUSION:
1. Intraoral aging – modifies physical and
mechanical properties – bond failure at lower
magnitudes
2. Bond strength data interpretation – limited to
relative effectiveness of adhesives and not
extrapolated to clinical ‘Gold standard’
3. Understand limitations of materials arising
from aging, modify expectations and monitor
treatment progress

4. Clinically relevant methodological approaches –
Accredited Standards Committee 156 for
Medical Devices Task Group- in 1990 by ADA

Orthodontic bonding to artificial tooth surfaces:
Clinical versus laboratory findings – AJO-DO 2000
- Bjorn Zachrisson
Striking difference between lab and clinical findings
1. Continually increasing tensile or shear load
applied in lab - not a true representative of
clinical force application
2. Type of debonding forces
3. Complex oral environment not reproducible in
lab – temp, stresses, humidity, acidity, plaque

 Lab studies – which product / material most
valuable to include in supplementary clinical
evaluation
 CLINICAL SUCCESS IS THE FINAL TEST.

DEBONDING
“The entire cycle of bonding,
treatment and debonding
should preserve the integrity
of enamel as far as
possible.”

 After debonding – tooth exposed to oral
environment for the remainder of the life of
the tooth
 As important to debond safely as it is to bond
strongly
 Greater strength of adhesives – potential
damage during debonding

Definition:
To remove the attachment and all the adhesive
resin from the tooth and restore the surface as
closely as possible to its pre-treatment
condition without inducing iatrogenic
damage.

DEBANDING:
 Retained by elasticity of band material
 GIC / Zn-phosphate – no strong bond to
enamel
 No risk of enamel damage
Procedure:
1. Band-removing plier
2. Break cement attachment and lift off band
3. Maxillary – first debonding force – palatal
4. Mandibular – buccal
5. Residual cement - scaling

DEBONDING OF BRACKETS:
Principles:
1. Minimum damage to enamel – fracture
• Within bonding material itself
• Between bracket – resin – most desirable
• Between resin – enamel - undesirable
1. Failure has to be induced between bracket and
resin
2. Distorting metal bracket base – non-reusable
3. Remaining adhesive cleaned-up

5. Debonding ceramic brackets problematic -
6. Bracket bases cannot be distorted
• Grind brackets – rotary instruments
• Mechanical instead of chemical bond
between base and resin
• Heat to soften resin, for easy removal –
electrothermal / lasers

2 stages:
1. Bracket removal
2. Removal of residual adhesive

1. BRACKET REMOVAL: - Instruments used
A. Utility pliers – Weingart/How
– pinch & peel
- distortion
Metal brackets

B. Debonding pliers:
 Sharp beaks
 Shear force
 Less residue on enamel – damaging to enamel

C. Specially designed pliers:
 Engage wing of bracket
 Braces beak against tooth
 Tensile force
 All adhesive left behind

Nature of force application :

PEELING
 Peripheral stress
concentration- fail
at low force values
 Adhesive-bracket
interface
 Minimum bracket
distortion
 Recycled

Ceramic brackets
1. Pistol-grip plier:
 Horizontally
 Handles squeezed
 Jaws contact tie-wing
 Pulled away

2. ETM pliers #346:
 Sharp-edged
 Enamel-adhesive interface
 Wedging effect

3. Electrothermal debonding:
 Engages O-G slot
 Torsional force

 Cylindrical handpiece connected to a rechargeble
direct current unit.
 Handpiece contains an heating element that
maintains a working temperature between 338°C
- 421°C
 Spring loaded trigger.

Bishara & Dougan
 Very high temperature - damage to the pulp.
 Patient - slight discomfort and apprehension.
 More suitable to ceramic brackets.
Sheridan & Brawley
 Rise in temp not harmful to pulp

4. Laser debonding:
 CO2 and ND:YAG Lasers.
 Softening of composite by heat produced by laser
beam
Strobl et al (AJO 1992)
Disadvantages of Thermal debracketing –
 Heats up - to be cooled after removing few
brackets
 Designed for specific bracket design

Advantages of Laser debonding-
1. Compact debonding instrument - atraumatic
debonding
2. Heat produced is localised and controlled
3. Can remove any type of ceramic bracket

5. Modified ceramic brackets:
 Vertical scribe line in base
 Pliers M-Dly grip bracket ears
 Bracket folds on vertical line

2. REMOVAL OF ADHESIVE:

Instruments used:
1. Scaler
2. Scraping with a sharp band or bond removing
plier
3. Burs
• Dome-shaped TC bur
• Ultrafine diamond bur
• White stone finishing bur

EFFECTSON ENAMEL

STRUCTURE OF NORMAL ENAMEL:
 Presence of perichymata and imbrications.

 Changes in microstructure of enamel surface
with age - 0-2 µm per year

Influence on enamel by different debonding
techniques:
Enamel Surface Index - Zachrisson and Artun
(1979-AJO)
0 – Perfect surface - none
1 – Satisfactory – TC burs – 25,000rpm
2 – Acceptable – fine sandpaper
3 – Imperfect – medium sandpaper
4 - Unacceptable - diamondwww.indiandentalacademy.com

 Combination technique
•Hong and Lew (1995-EJO)
•Bulk removal - high speed bur and plier
•Slow speed TC bur for finishing
 Average enamel loss - 7.4 µm with careful use of
TC bur.

Enamel Cracks
 Sharp sound associated with bracket removal
-indicate formation of enamel cracks.
1. Vertical – common
2. Horizontal & oblique – few
3. Maxillary central incisors, canines
4. Pre-treatment records

Enamel Tearouts

DECALCIFICATION AND DEMINERALISATION
“Scars of the operation”

Definition: Loss of calcified tooth substance
 Early lesion – opaque white spot
 Active lesion – chalky white
 Continued demineralisation – frank cavitation
DECALCIFICATION

Etiology :
1. Oral hygiene – ortho attachments make
cleaning more difficult
2. Diet – sugary foods/ drinks
- FA – reduce tongue and salivary activity
- decreased clearance
3. Appliance type and design
4. Bonding technique – removal of flash

Preventive measures:
1. Patient selection & education – remotivation
2. Oral hygiene instructions
3. Mechanical plaque removing –
• Brushing – twice
• Interdental cleaning aid
• Oral irrigation – adjunct
1. Reduce plaque retention by appliance –
• Minimal loops
• Check cement around bands

5. Protect enamel surface –
 Topical fluorides before and during treatment
• Fluoridated toothpaste
• 0.5% NaF mouthrinse
• Professional Fl gel application
 Coat with adhesive – Protecto, Nuva-seal

Management of decalcification during treatment:
1. Remove / finish treatment in shortest time?
2. Removal – regression of lesions
- provided other factors removed
3. Ogaard et al – white spots – fluoride agents
- not on buccal lesions – arrested
- remineralization by saliva
4. Croll and Cavanagh – Acid pumice abrasion
- 18% HCl + Pumice
- rub on affected enamelwww.indiandentalacademy.com

Clinical Implications
 Use of brackets that have mechanical retention.
 Use of debonding instruments that leave all or
most of the composite on the tooth surface.
 Avoid scraping away adhesive remnants with
hand instruments.
 Use of slow speed tungsten carbide bur for
finishing.
 Intentional leaving of adhesive to seal pre-
treatment surface irregularities.

REFERENCES
1. Orthodontics – Current Principles & Techniques
- T.M. Graber, R.L. Vanarsdall,Jr
2. Contemporary Orthodontics - William R.Proffit
3. Textbook of Orthodontics – Samir Bishara
4. Orthodontic materials – Brantley & Eliades
5. T.M. Graber – Orthodontics: Principles & Practice, III Ed.
6. Orthodontics: State of the art- Essence of the Science –
Lee Graber
7. Bond strength and durability of glass ionomer cements
used as bonding agents - AJO July 1989 -Klockowski,
Davis, Joynt, Wieczkowski, and MacDo

8. A new light-cured glass ionomer cement that bonds
brackets to teeth without etching in the presence of
saliva -AJO-DO SEP 1995 -Silverman, Cohen
9. Evaluation of fluoide release from an orthodontic
bonding system – AJO-DO Aug 1991 -Samir E.
Bishara, Edward J. Swift, Jr., Daniel C. N. Chan,
10. A universal direct bonding system for both metal
and plastic brackets.-AJO 1972 - Silverman et al
11. A new approach to indirect bonding technique using
light-cure composites - AJO-DO 1997
- Paul Kasrovi et al

12. Efficient and effective indirect bonding -Anoop Sondhi
-AJO-DO 1999
13. Clinical comparison of direct versus indirect bonding
with different bracket types and adhesives – AJO 1978
-Zachrisson and Brobakken
14. Assessment of bracket strength and bond strength
when comparing direct bonding to indirect bonding
techniques - AJO 1982 - Aguirre, King & Waldron
15. Recent advances in bonding to gold, amalgam and
porcelain – JCO 1993 – Zachrisson et al
16. Indirect bonding: simplicity in action – JCO 1979 –
Thomas R. G.

17. Indirect bonding of orthodontic attachments – AJO
1977 – Moin & Dogon
18. Intraoral aging of orthodontic materials : The picture
we miss and its clinical relevance- AJO-DO 2005
-Eliades and Bourauel
19. Orthodontic bonding to artificial tooth surfaces:
Clinical versus laboratory findings – AJO-DO 2000
- Bjorn Zachrisson
20. Decalcification during orthodontic treatment with fixed
appliances – An overview – BJO 1992 – L. Mitchell

21. Laser debonding - AJO 1992- Strobl et al
22. Electrothermal debracketing – AJO 1986 – Sheridan
et al

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