Abstract: The objectives of debonding are 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 carelessly. The present article gives us an overview of the best possible methods so as to have an ideally desired tooth structure after debonding.

1 2Neelutpal Bora, Nabanita Baruah1 2Lecturer, Reader, Department of Orthodontics and Dentofacial OrthopedicsRegional Dental College, Gawhati.

INTRODUCTION:

An expectation of beautiful smiles at the end of orthodontic

treatment is a primary concern to each patient, but is also

equally concerned with appearance while undergoing

treatment. Many attempts have been made by manufacturers

to meet this demand. Characteristic of an ideal orthodontic

appliance include good esthetics and optimum technical

performance. Reports of enamel fracture and cracks during

debonding has raised questions about the safety of various

procedures used to remove these attachments,1-4 although

the tensile strength of ceramic is greater than that of stainless

steel, less energy is used to cause fracture of ceramic brackets

compared with conventional stainless steel brackets.4 This

phenomenon is related to fracture toughness or the ability of a

material to resist fracture and ceramic brackets have

substancially less fracture toughness when compared to

stainless steel brackets.5,6The adhesion between the resin

and bracket base has increased to a point where the most

common site of bond failure during debonding has shifted

from bracket base- adhesive interface to enamel adhesive

interface which could increase the risk of enamel damage

which is a less desirable.7-9 This shift has led to an increase in

the incidence of bond failures within the enamel surface.10

Different techniques used for debonding:

Manufacturers have developed various debonding techniques

specially for ceramic brackets, including the use of debonding

pliers and ligature cutting pliers to apply a squeezing force at

the bracket base as well as the application of a shear torsion

force with a specially designed instrument.6, 11 Alternate

debonding techniques that minimize the potential for bracket

failure as well as trauma to the enamel surface during

debonding. Ultrasonic debracketing tips uses specially

designed tips applied at the bracket adhesive junction.1,3, 5-

7,12 Thermal debonding has also been suggested as a method

for debonding ceramic brackets.9,13

Clinical Procedures

Although several methods have been recommended in the

literature for bracket removal and adhesive cleanup, and some

discrepancy of opinion still exists.

The clinical debonding procedure may be divided in two

stages:

DEBONDING IN ORTHODONTICS : A REVIEW

Journal of Dental Sciences

University

Key word s: Debonding, iatrogenic, adhesive resin.

Source of support : NilConflict of Interest : None

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Review Articles

1. Bracket removal

2. Removal of residual adhesive

Bracket removal: steel brackets (Fig.1)

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. Several pliers are available for this

purpose. A gentler technique is to squeeze

the bracket wings mesio distally and lift the bracket off with a

peel force. This is particularly useful on brittle, mobile, or

endodontically treated teeth. The brackets are deformed

easily and are less suitable for recycling when the latter

method is used. This is a recommended technique, in which

brackets are not deformed. This technique uses a peeling-type

force, which is most effective in breaking the adhesive bond.

A peel force, as in peeling an orange, creates peripheral stress

concentrations that cause bonded metal brackets to fail at low

force values.11-12 The break is likely to occur in the adhesive

bracket interface, thus leaving adhesive remnants on the

enamel. Attempts to remove the bracket by shearing it off (as

is done in removing bands) can be traumatic to the patient and

potentially damaging to the enamel.

Bracket removal: ceramic brackets (Fig.2)

With the introduction of ceramic brackets, a new concern over

enamel fracture and loss from debonding has arisen. Because

of differences in bracket chemistry and bonding

mechanisms, various ceramic brackets behave differently on

debonding. For example, ceramic brackets using mechanical

retention cause fewer problems in debonding than do those

using chemical retention. In this regard, some knowledge

about the normal frequency, distribution, and orientation of

enamel cracks in young and in older teeth is important.

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 still may

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. More

recent ceramic brackets have a mechanical lock base and a

vertical slot-that will split the bracket by squeezing.6-8

Separation is at the bracket-adhesive interface, with little risk

of enamel fracture. Low-speed grinding of ceramic brackets

with no water cool ant may cause permanent damage or

necrosis of dental pulps. Therefore water cooling of the

grinding sites is necessary. High-volume suction and eye

protection also are recommended to reduce the number of

ceramic particles spread about the operatory area. Finally,

thermal debonding the use of lasers have the potential to be

less traumatic and less risky for enamel damage, but these

techniques are still at an introductory stage.

Removal of residual adhesive

After debonding of brackets evaluation of residual adhesive

and sites of bond failure are recorded using Adhesive

Remnant Index (ARI) . It is a four scale index to determine

the amount of adhesive remnants on the enamel surface after

debracketing and was introduced by Artun and Bergland. 14

Adhesive Remnant Index (ARI)

Score 0 – No adhesive left on the enamel.

Score 1 – Less than half of the adhesive left on the

enamel.

Score 2 – More than half of the adhesive left on the

enamel.

Score 3 – All adhesive left on the tooth surface with

distinct impression of the bracket mesh.

Because of the color similarity between present adhesives and

enamel, complete removal of all remaining adhesive is not

achieved easily. 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

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become unesthetically discolored

with time. The removal of excess adhesive may be

accomplished by (1) scraping with a sharp band or bond-

removing (2) using a suitable bur and contraangle .(Fig.3)

Although the first method is fast and frequently successful on

curved teeth (premolars, canines), it is less useful on flat

anterior teeth. A risk also exists of creating significant scratch

marks. The preferred alternative is to use a suitable dome

tapered tungsten carbide bur (#1171 or #1172) in a contra

angle handpiece. Clinical experience and laboratory studies

indicate that about 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 used when the last remnants are

removed because water lessens the contrast with enamel.

Speeds higher than 30,000 rpm using fine fluted tungsten

carbide burs may be useful for bulk removal but are not

indicated closer to the enamel because of the risk of marring

the surface. Even ultra fine high-speed diamonds produce

considerable surface scratches. Slower speeds (10,000 rpm

and less) are ineffective, and the increased jiggling vibration

of the bur may be uncomfortable to the patient.

When all adhesive has been removed, the tooth surface may

be polished with pumice (or a commercial prophylaxis paste)

in a routine manner.

CHARACTERISTICS OF NORMAL ENAMEL

Apparently not every clinician is familiar with the dynamic

changes that continuously take place throughout life in the

outer, most superficial enamel layers. Because a tooth surface

is not in a static state, the normal structure differs

considerably between young, adolescent, and adult teeth.

Normal wear must be considered in any discussion of tooth

surface appearance after debonding. The characteristics are

visible on the clinical and microscopic levels.

The most evident clinical characteristics of teeth that have just

erupted into the oral cavity 3 perikymata that runs around the

tooth over its surface

By scanning electron microscope the open enamel prism ends

are recognized as holes In adult teeth the clinical picture

reflect and exposure to varying mechanical forces (e.g.,

brushing habits and abrasive food stuffs). In other words the

perikymata ridges are worn away and replace scratched

pattern .(Fig.4)

Influence on Enamel by Different Debonding Instruments

The condition of the enamel surface is evaluated according to

the ENAMEL SURFACE INDEX (ESI) system introduced

by Bjorn U. Zachrisson and Jon Arthun.15

Score 0 = Perfect surface. No scratches, distinct intact

perikymata.

Score I = Satisfactory surface. Fine scratches, some

perikymata.

Score 2 = Acceptable surface. Several marked and some

deeper scratches, no perikymata.

Score 3 = Imperfect surface. Several distinct deep and coarse

scratches, no perikymata.

Score 4 = Unacceptable surface. Coarse scratches and deeply

marred appearance.

By proposing an enamel surface index with five scores (0to 4)

for tooth appearance and using replica scanning electron

microscopy and step-by-step polishing, Zachrisson and Artun

were able to compare different instruments commonly used in

debonding procedures and rank their degrees of surface

marring on young permanent teeth. (Fig.5)

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The study demonstrated that

(1) diamond instruments were unacceptable (score 4), and

even fine diamond burs produced coarse scratches and gave a

deeply marred appearance;

(2) medium sandpaper disks and green rubber wheel

produced similar scratches (score3) that could not be polished

away;

(3) fine sandpaper disks produced several considerable and

some even deeper scratches and a appearance largely

resembling that of adult teeth (score 2);

(4) plain cut and spiral fluted tungsten carbide burs operated

at about 25,000 rpm were the only instruments that provided

the satisfactory surface appearance (score 1); however, (5)

none of the instruments tested left the virgin tooth surface

with its perikymata intact (score 0).

The clinical implication of the study is that tungsten carbide

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. For optimal

efficiency the bur must be replaced when it becomes blunt.

Increased diameter burs or high-speed equipment also may be

used for bulk removal. The oval tungsten carbide bur is useful

for removing adhesive remnants after debonding retainers

and brackets on the lingual surfaces of teeth. Tungsten carbide

burs can give the ideal tooth condition desired after

debonding .(Fig.6)

CONCLUSION:

The present study suggests that an ideal debonding technique

should take the least time to debond the brackets with minimal

enamel damage and residual adhesive remaining on the

enamel surface. In order to achieve a desirable finish to any

orthodontic case after debonding tungsten carbide bur is

useful for removing adhesive remnants after debonding

retainers and brackets on all the surfaces of teeth.

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CORRESPONDENCE AUTHOR :

Dr. Neelutpal Bora

Lecturer,

Department of Orthodontics and Dentofacial Orthopedics

Regional Dental College, Guwahati, Assam

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