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rev port estomatol med dent cir maxilofac . 2017;58(2):65-70 67

Table 1. Search strategy
Keywords/MeSH terms Literature search strategy Database
1 orthodontic brackets [Mesh]
#1 AND #3
2 bracket*
#1 AND #5 Pubmed
3 crowns [Mesh] #1 AND #3 AND #8
#1 AND #5 AND #8
4 crown*
5 acrylic resins [Mesh]
#2 AND 4
6 acrylic*
#2 AND #6 ClinicalKey / Lilacs / WOS
7 provisional material* #2 AND #7

8 dental bonding [Mesh]
#, Search; Mesh, medical subjects heading ; *, truncation of a text word; WOS, Web of Science

ering the purpose of the present study. The articles of abstracts
with not enough relevant information were also obtained. The
Studies identifed through
references of relevant publications were hand-searched, and all database searching (n=2044) Studies identifed through
other sources (n=7)
articles containing the words bond and acrylic together with IDENTIFICATION Pubmed (n=689)
ClinicalKey (n=769)
brackets were selected as additional relevant publications that Web of Science (n=138)
could have been missed by the search engines. Book chapters, Lilacs (n=64)
abstracts, letters and reviews were excluded since the aim of this
Studies after title screened (n=28)
systematic review was to evaluate primary studies. Studies excluded by title after
The experimental conditions were categorised in a list of duplicates removed (n=2016)
34 items. The two reviewers discussed those items before read- SCREENING
ing the full text in order to reach an agreement about the items
to include. During the full articles reading, the reviewers inde- Studies screened by abstract (n=14)
pendently assessed whether the experimental conditions
were reported in the study. Moreover, to minimise bias, the two
observers independently evaluated the validity of original
studies and read them twice in different times and sequences. ELIGIBILITY Full-text articles assessed for eligibility (n=12)
Full-text articles excluded
with reasons (n=2)
Results Studies included in qualitative

The results of this review were described narratively. The search INCLUDED analyses (n=10)
results and the initial number of published studies presented by
the various databases are provided in Figure 1. Of the studies col- Figure 1. Search results followed in the review adapted
lected from all the databases, 28 based on their title and 14 based from Moher et al, 2009. 6
on their abstract, only 10 studies fulflled the selection criteria
after being individually examined twice by the two reviewers. Two
of the trials were rejected: one because it was decided to defnite- ods of all 10 studies, are presented in Appendix 1. The variables
ly not include polycarbonate crowns as acrylic ones after review- relevant to bond strength and the bond strength mean values
ers discussion, and the other because its authors showed bond were summarised in Appendixes 2 and 3.
strength values in Newtons (N) rather than megapascals (MPa).
The experimental conditions for in vitro tests are shown in Type of acrylic surface (n=5). Of the five publications consider-
Table 2. The selected studies on acrylic surfaces revealed no ing different surfaces for orthodontic brackets bonding, two eval-
data on tensile bond strength and, besides the inclusion crite- uated five different temporary crown materials, one evaluated
ria items, the surface treatment and the crosshead speed were four and two evaluated three different materials. All studies 2,4,5,7,8
the most frequently reported conditions for the shear bond test included at least one group of bis-acryl/bis-GMA 2,4,5,7,8 composite
(100%). Within the 10 selected studies, factors related to brack- resins and one of an acrylic resin based on methacrylate (MMA), 4
ets and samples storage were the second most relevant ones. polymethyl methacrylate (PMMA) 2,5,7,8 or poly ethyl methacrylate
The 10 selected articles were categorised by topics, accord- (PEMA). 2,4,7 One also included a resin based on urethane dimeth-
ing to the type of acrylic surface (n=5), type of surface treatment acrylate (UDMA). All studies performed shear bond tests and
7
(n=7), type of adhesive (n=5) and ageing samples protocols (n=3) presented the mean results in MPa. Three revealed a significant
used. The aims and main results, as well as the statistical meth- influence of the surface type on the bond strength of orthodon-