Odontologia

British Journal of Orthodontics/Vol. 25/1998/283–287

Clinical Performance of Orthodontic Brackets
and Adhesive Systems: A Randomized
Clinical Trial
S . S U N N A , B . D . S ., M . D E N T . S C ., M . O R T H ., R . C . S . ( E N G . )
W . P . R O C K , B . D . S ., D . D . S ., F . D . S . R . C . S ., D . O R T H . ( E N G )

School of Dentistry, The University of Birmingham, St ChadsQueensway, Birmingham, B4 6NN, UK

Abstract. The aim of the study was to evaluate and compare the clinical performance of adhesive precoated brackets
(APC) with that of two types of uncoated bracket bases, Straight-Wire and Dyna-Lock, bonded using two types of
orthodontic adhesives, Transbond XT, and Right-On. Forty consecutive orthodontic patients entered the trial and 607
brackets werebonded. The incidence and site of first time bond failures were recorded over a period of 1 year. The time
required for bonding was also recorded.
The overall bond failure rate was 6·6 per cent. There were no significant differences between the failure rates of the five
groups, or between the upper and lower arch. However, significantly more brackets failed on the left side than on the right.Premolar brackets were lost most often, whilst incisor brackets failed least. No association was found between bond failure
and time elapsed since bonding. Bonding time was least with Right-On adhesive. There were no significant differences
between bonding times using APC or Transbond.
Results of the present study conflict with those of a previous ex vivo study by the authors, using the same materialsand
bonding technique. Suggested reasons for this are discussed.
Index Words: Adhesive precoated brackets, bracket bonding, clinical failure rate, chair side time.
Refereed Paper
Introduction
Bonding of orthodontic attachments to enamel has been in
use for over 40 years, although the exact date of the first use
of the technique is disputed (Cueto, 1990; Mitchell 1992;
Newman 1992).
Thesuccess of fixed appliance therapy depends on
attachments having adequate bond strengths and a low
failure rate. The overall time required to place an appliance
is an important factor in the cost of treatment, whilst the
need to replace brackets frequently may severely impair
the progress of fixed appliances, and can be costly in terms
of materials and time.
Orthodontic attachments are subjectedto a large
number of forces in the mouth, resulting in a complex
distribution of stresses within the adhesive and at its
junctions with the enamel and the bracket base. Bond
strength to enamel will depend on a large number of factors
including the nature of the enamel surface, enamel conditioning procedures, the types of adhesive used, and the
shape and design of the bracket base.
AdhesivePrecoated Brackets (APC; 3M Unitek, P.O.
Box 1, Bradford, BD5 9UY, UK) have been introduced
recently. The composite used to precoat the brackets is a
version of Transbond XT (3M Unitek, P.O. Box 1,
Bradford, BD5 9UY, UK), modified by an increased
viscosity (Bergstrand, 1996, personal communication).
Cooper et al. (1992) listed the following advantages of APC
over other systems:
Consistentquality and quantity of adhesive.
Easier clean-up following bonding.
Reduced waste during bonding.
0301-228X/98/003000+00$02.00

Improved asepsis.
Better inventory control.
In addition, improved control of both the bracket and
adhesive associated with the use of APC is claimed to
improve bond strength and clinical failure rate (3M Unitek
product literature, 1995).
A previous study by theauthors (Sunna and Rock, in
press) compared the ex vivo shear bond strength of APC
with that of two types of uncoated bracket bases, StraightWire (Orthologic, Summit House, Summit Road, Potters
Bar, EN6 3EE, UK) and Dyna-Lock (3M Unitek, P.O. Box
1, Bradford BD5 9UY, UK), bonded using two types of
adhesives, Transbond XT and Right-On (TP Orthodontics,
2 Bruntcliffe Way, Morley, Leeds LS27...