| dc.description.abstract | Background: The relationship between the curvature of the tooth and the curvature
on the corresponding bracket is of vital importance. The closer the curvature of the
base to that of the tooth, the closer adaptation it will assume. It will consequently have
better adhesion, retention and distribute the forces on the tooth more efficiently in all
dimensions. However, there is a lack of literature relating the buccal curvature of the
tooth to the curvature of the corresponding orthodontic bracket. This dissertation
investigated this relationship with the help of a novel methodology using Micro-
Computed Tomography (Micro-CT).
Aim: The aim of the study was to compare the buccal curvatures of the maxillary
second premolars with the curvatures of three orthodontic bracket brands using a
Micro-CT scanner.
Methodology: The study sample included 33 randomly selected maxillary second
premolars from archived orthodontic diagnostic models and corresponding orthodontic
brackets from three manufacturers: Bioquick (Forestadent), Innovation (GAC) and
Victory Series (3M Unitek). The sample was scanned using a Nikon Metrology XTH
225 ST X-ray micro-computer tomography scanner (Yokohama, Japan) at 100kV with
a beam current of 200μA with an exposure of 1fps. The images were analysed on
Volume graphics VG Studio max 3.2.5. The curvatures of the brackets at the mesial
and gingival margin were isolated and the central angle of these curvatures were
recorded in degrees. The corresponding curvature angles on the teeth were also
recorded of each bracket. The angles of the brackets and the angles on the teeth were
analysed to determine which bracket had the lowest angular difference. The angular
differences were compared using a two-way ANOVA and a Bonferroni Pairwise
Comparison.
Results: The results of the study showed there to be no standardisation between
angulations of the 3 bracket brands. It also confirmed the results in the literature which
states the existence of a great variation in curvature between maxillary second
premolars. A statistically significant interaction was found between the angles of the 3
brackets and the angles on the teeth p < 0.0001. The lowest angular difference for the
joint 3 and 4 mm prescriptions at the mesial margin of the brackets was that of Victory Series -1.623 (±5.920) and Bioquick had the lowest angular difference for the joint
prescriptions at the gingival margin 5.836 (±13.580). The difference at the mesial
margin between the Victory series and Innovation was -4.494 (SE±1.681); p = 1 and
between Victory series and Bioquick was -5.145 (SE±1.681); p = 1. Both were
statistically insignificant. The difference between Bioquick and Innovation at the
gingival bracket margin was 0.811(SE±1.681); p = 0, the difference between Bioquick
and Victory series was 11.908 (SE±1.681); p = 0, both were statistically significant.
Conclusion: The results indicated the best performing bracket at the mesial margin
to be that of Victory series. This result was followed by Innovation and Bioquick who
were closely matched with no significant difference. The best performing bracket at
the gingival margin was Bioquick followed by Victory series and Innovation. The
curvature of Innovation greatly underestimated the tooth curvature. The best overall
angular difference was that of Victory series. | en_US |
