Original article
Quantitative analysis of enamel on debonded orthodontic brackets

https://doi.org/10.1016/j.ajodo.2017.01.020Get rights and content

Highlights

  • Enamel damage was more frequent with ceramic bracket removal than metal brackets.

  • Damage was less when ceramic brackets were attached with RMGIC than composite resin.

  • Ceramic bracket fracture was greatest with 2-step etch-and-bond composite resin.

  • The most common bond failure site was the bracket-bonding material interface.

  • Maxillary lateral incisors had a greater risk of damage than central incisors and canines.

Introduction

Iatrogenic damage to the tooth surface in the form of enamel tearouts can occur during removal of fixed orthodontic appliances. The aim of this study was to assess debonded metal and ceramic brackets attached with a variety of bonding materials to determine how frequently this type of damage occurs.

Methods

Eighty-one patients close to finishing fixed orthodontic treatment were recruited. They had metal brackets bonded with composite resin and a 2-step etch-and-bond technique or ceramic brackets bonded with composite resin and a 2-step etch-and- bond technique, and composite resin with a self-etching primer or resin-modified glass ionomer cement. Debonded brackets were examined by backscattered scanning electron microscopy with energy dispersive x-ray spectroscopy to determine the presence and area of enamel on the base pad.

Results

Of the 486 brackets collected, 26.1% exhibited enamel on the bonding material on the bracket base pad. The incidences of enamel tearouts for each group were metal brackets, 13.3%; ceramic brackets, 30.2%; composite resin with self-etching primer, 38.2%; and resin-modified glass ionomer cement, 21.2%. The percentage of the bracket base pad covered in enamel was highly variable, ranging from 0% to 46.1%.

Conclusions

Enamel damage regularly occurred during the debonding process with the degree of damage being highly variable. Damage occurred more frequently when ceramic brackets were used (31.9%) compared with metal brackets (13.3%). Removal of ceramic brackets bonded with resin-modified glass ionomer cement resulted in less damage compared with the resin bonding systems.

Section snippets

Material and methods

Ethics approval for the study was obtained from the Human Research Ethics Committee (number 1136902) of the University of Melbourne in Australia. Patients close to finishing fixed orthodontic treatment were recruited from 5 private orthodontic practices. Practices were invited to participate if they met the following inclusion criteria: (1) the clinicians in the practice used either metal In-Ovation R brackets (GAC International, Bohemia, NY) or ceramic In-Ovation C brackets (GAC

Results

The frequency of enamel presence on the bonding material on the bracket base pad is shown in Table I; there were differences between the groups (P = 0.001). Of the 486 brackets collected, 26.1% had detectable enamel on the base pad. The MEC group had a significantly lower incidence of tearouts compared with the CEC group (P = 0.015). There were significant differences in enamel damage when ceramic brackets attached with different materials were compared, with the CEC and CSEP groups having

Discussion

The force used to debond brackets can be applied to the bracket or to the bonding material, with failure occurring at the weakest interface or within the material with the weakest cohesive strength. In this study, clinicians applied a “lift-off” force to the wings of the metal brackets or force to the adhesive of the ceramic brackets. None of the metal brackets collected in this study fractured when removed. The BARI scores indicated failure predominantly at the bracket-adhesive interface (BARI

Conclusions

The following conclusions can be made from this study:

  • 1.

    Enamel damage regularly occurs during debonding and can be quite severe, although major damage is limited to a relatively few patients.

  • 2.

    Damage occurs more frequently with removal of ceramic brackets than with metal brackets.

  • 3.

    Ceramic brackets attached with RMGIC showed less damage (frequency and amount) than ceramic brackets attached with composite resin.

  • 4.

    Ceramic bracket fracture was greatest with 2-step etch-and-bond with composite resin, and

Acknowledgment

We thank Roger Curtain at the Bio21 Institute and Emily Szycman and David Thomas at the Melbourne Dental School.

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  • Cited by (0)

    All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported.

    Supported by a grant from the Australian Dental Research Foundation and the Australian Society of Orthodontists, Foundation for Research and Education.

    Deceased.

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