Ahmed, Tamzid
(2018)
Measurement of orthodontic bracket debonding force on different teeth using a prototype device equipped with force sensitive resistor: an in-vitro and in-vivo study.
Masters thesis, Universiti Sains Malaysia.
Abstract
Orthodontic bonding studies should emphasize more on testing the effect of oral
environment on the wide range of orthodontic bracket-adhesive systems that are evolving
regularly. Therefore, the objective of this present study is to introduce a prototype device
capable of debonding orthodontic brackets and measuring the peak debonding force
clinically by a calibrated force sensor mechanism. Ninety-nine (99) maxillary premolar
samples were prepared for the in-vitro studies. Standardized bonding protocol was
maintained by a single clinician utilizing 0.022 metallic brackets (HKS 3, Ortho Classic,
McMinnville, USA), Transbond XT adhesive with Transbond Plus self-etching primer
(3M Unitek, Monrovia, California, USA) and LED light curing (model- DB686, COXO,
Guangdong, China) for 20 seconds. Sixty (60) samples were divided equally into two (2)
groups for the validation study. For intra and inter-examiner reliability, thirty-nine (39)
samples were equally divided into three (3) groups. The brackets were debonded after
twenty-four (24) hours of bonding. Clinically, orthodontic bracket debonding forces were
measured on 260 different teeth in thirteen (13) patients after comprehensive fixed
orthodontic treatment and divided equally into ten (10) groups from the central incisor to
second premolar. Following debonding procedure, intra-oral micro-photograph of each
tooth was taken using portable digital microscope for assessing the bracket-failure pattern
by 4-point scale of adhesive remnant index (ARI). Statistical analysis includedindependent
samples t-test for validation study, intraclass correlation coefficient test for
intra and inter-examiner reliability, one-way ANOVA to compare in-vivo mean
debonding forces between different tooth groups and the non-parametric Kruskal-Wallis
test to compare in-vivo ARI between different tooth types. The significance level was set
at less than 0.05. The mean debonding force between the universal testing machine (10.43
± 2.71 N) and the prototype device (9.36 ± 1.65 N) was not significantly different (p =
0.072). The prototype device exhibited excellent intra and inter-examiner reliability (0.942
and 0.921). Significant difference (p < 0.001) of mean debonding force was found between
different types of teeth in-vivo. Clinically, ARI scores were not significantly different (p
= 0.921) between different groups but overall higher scores were predominant. The
prototype device can be recommended for measuring clinical bracket debonding force as
the device is validated, proved to be reliable and based on clinical ARI scoring caused less
iatrogenic enamel damage. Bracket debonding force should be measured on same tooth
from the same arch as significant difference of mean debonding force exists between
similar teeth of the upper and lower arches.
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