Two reviewers (MF and FI) independently screened the results of the search in electronic databases, which led to the identification of 8968 records. After removing the duplicates by using Mendeley Desktop 1.19.4 Reference Manager (England), 5932 records were screened. After exportation to Rayyan and analyses of the titles and abstracts, 74 studies were pre-selected for the full-text analysis by two reviewers (MF and FI). The kappa index (κ = 0.99) in the selection by title and abstract and in the selection by full reading was calculated by using Excel professional Plus 2016. Subsequently, the reviewers selected 44 studies (κ = 0.96) for qualitative analysis, and all were included in the meta-analysis. The reasons for exclusion of the studies are described in Fig. 1. Although the research sought articles based on clinical and in vitro studies, only in vitro studies met the inclusion criteria.
Characteristics of the included studies
The characteristics of the 44 studies are summarized in Supplementary Table 2, see online resource. The type of aging varied considerably, the majority of samples were stored in water at 37°C [22, 23, 32–41, 24, 42–45, 25–31], the second most common type of aging found was performed by thermal cycling [30, 38, 52–60, 41, 43, 46–51]. Other types also found were boiling and storage in water [50, 61, 62], storage in artificial saliva [31, 63], immersion in citric acid [50], artificial accelerated aging with exposure to ultraviolet rays (UV-B) [31, 64], and storage in 0.9% saline solution at 37°C [65].
There were 19 different types of procedures performed in the in vitro studies. These were categorized into the use of surface treatments or intermediate agents, according to Table 1. Surface treatments: air abrasion with aluminum oxide / silica-coated [26, 27, 40–42, 45, 46, 48, 50, 51, 54, 56, 28, 57–60, 64–66, 29, 31–33, 37–39], diamond bur [22, 30, 51, 54–60, 63, 64, 32, 35, 39, 42, 44, 46, 47, 49] silicon carbide paper [33, 66], phosphoric acid [22, 23, 42, 43, 47, 49, 50, 53, 56–58, 60, 30, 61, 63, 64, 31, 32, 34–37, 41] hydrofluoric acid [46, 58, 61] maleic acid [27], polyacrylic acid [27], acetone gel [28], liquid acetone [28], toluene [36], liquid alcohol [28], alcohol gel [28], plasma argon [29, 40], atmospheric plasma jet [56] Er:YAG laser [30, 63], Er,Cr:YSGG laser [47, 53]. Intermediate agent: silane [22, 24, 40, 42, 43, 45–47, 54–57, 25, 58, 62, 64, 65, 26, 28, 29, 33–35, 39], low-viscosity composite [32, 51, 63], adhesive. Among the adhesives, the following types were found: 2-steps conventional adhesive, 3-steps conventional adhesive, universal adhesive, self-etching adhesive. Adhesive systems were tested in 100% of the articles selected, but not tested in all groups. Most groups tested surface treatment concomitantly with intermediate agents.
Table 1
Types of chemical and physical treatments used for resin composite repair
Author/year
|
Country
|
Surface Treatment
|
Intermediate agent
|
|
|
|
|
Physical treatments
|
Chemical treatment
|
Physical / Chemical treatment
|
Others
|
|
|
Diamond
bur
|
Air abrasion
Oxide/ Silica
|
Phosphoric acid
|
Hydrofluoric acid
|
Silane coupling
Agent/ universal primer
|
Adhesive/
Bonding agent
|
CoJet System
|
|
Akgül, 2021
|
Turkey
|
-
|
Yes
|
Yes
|
-
|
-
|
Universal
|
Yes
|
-
|
Alqarni, 2018
|
Japan
|
-
|
-
|
-
|
-
|
Yes
|
Self-Etching
|
-
|
-
|
Altinci, 2018
|
Finland
|
-
|
-
|
-
|
-
|
Yes
|
Universal
|
Yes
|
-
|
Aquino, 2020
|
Brazil
|
Yes
|
Yes
|
Yes
|
-
|
Yes
|
Conventional – 2-Step
|
-
|
-
|
Ayar, 2018
|
Turkey
|
-
|
-
|
Yes
|
Yes
|
-
|
Conventional 2-Step
|
-
|
-
|
Ayres, 2019
|
Brazil
|
-
|
Yes
|
-
|
-
|
Yes
|
Conventional 3-Step
|
-
|
Plasma Argon
|
Bektas, 2012
|
Turkey
|
Yes
|
-
|
Yes
|
-
|
-
|
Universal
|
-
|
Er:YAG laser
|
Benzi, 2021
|
Brazil
|
Yes
|
Yes
|
Yes
|
-
|
-
|
Universal
|
-
|
-
|
Brum, 2017
|
Brazil
|
-
|
Yes
|
-
|
-
|
Yes
|
Conventional 3-Step
|
-
|
Acetone gel/ liquid
Alcohol gel/ liquid
|
Chuenweravanicha, 2022
|
Thailand
|
Yes
|
Yes
|
Yes
|
-
|
Yes
|
Universal
|
-
|
-
|
Dias, 2003
|
USA
|
-
|
-
|
-
|
-
|
Yes
|
Conventional 3-Step/ Universal 1-Step / Self-Etching
|
Yes
|
-
|
Dias, 2011
|
Brazil
|
Yes
|
-
|
Yes
|
-
|
Yes
|
Universal
|
-
|
-
|
Dieckmann, 2020
|
Switzerland
|
Yes
|
Yes
|
-
|
-
|
Yes
|
Conventional – 3 Step
|
-
|
-
|
Dursun, 2021
|
Turkey
|
-
|
Yes
|
Yes
|
-
|
-
|
Conventional 3-Step
|
-
|
Er, Cr: YSGG laser /
Silicon carbide ( SiC)
|
El-Askary, 2012
|
Egypt
|
-
|
-
|
Yes
|
-
|
Yes
|
Universal
|
-
|
-
|
Hoseinifar, 2021
|
Iran
|
-
|
-
|
Yes
|
-
|
Yes
|
Universal/ Conventional 2-step
|
-
|
|
Imbery, 2014
|
USA
|
Yes
|
-
|
Yes
|
-
|
Yes
|
Adhesive Composite Primer / Total-etching
|
-
|
-
|
Jusué-Esparza, 2022
|
Uruguay
|
-
|
-
|
-
|
-
|
Yes
|
Self-Etching / Universal
|
-
|
-
|
Karadağlioğlu, 2022
|
Turkey
|
-
|
-
|
-
|
-
|
-
|
Universal
|
-
|
Diamond coarse brown disc / Al2O3 extra coarse disc / Silicon carbide
|
Kiomarsi, 2017
|
Iran
|
Yes
|
-
|
Yes
|
-
|
Yes
|
Conventional 2-Step
|
-
|
Er,Cr:YSGG laser
|
Kuşdemir, 2021
|
Turkey
|
-
|
Yes
|
-
|
-
|
-
|
Universal
|
-
|
-
|
Lemos, 2016
|
Brazil
|
-
|
-
|
Yes
|
-
|
-
|
Conventional 3-Step AND 2-Step
|
-
|
-
|
Melo, 2011
|
Brazil
|
Yes
|
Yes
|
Yes
|
-
|
Yes
|
Adhesive Total-Etching
|
-
|
-
|
Michelotti, 2020
|
Switzerland
|
Yes
|
Yes
|
-
|
-
|
Yes
|
Conventional
Universal
|
Yes
|
-
|
Nagano, 2018
|
Japan
|
-
|
-
|
-
|
-
|
Yes
|
Self-Etching
|
-
|
-
|
Negreiros, 2021
|
Brazil
|
-
|
Yes
|
-
|
-
|
Yes
|
Conventional 3-Step
|
-
|
Plasma Argon
|
Ozcan, 2007
|
Brazil
|
-
|
-
|
Yes
|
-
|
-
|
Conventional 2- Step
|
Yes
|
-
|
Ozcan, 2013
|
Switzerland
|
Yes
|
-
|
-
|
-
|
-
|
Conventional 3- Step AND 2-Step/ Self-Etching
|
Yes
|
Layer of unfilled resin
|
Papacchini, 2007
|
Italy
|
-
|
Yes
|
Yes
|
-
|
Yes
|
Self-Etching/
Self-cure
|
-
|
-
|
Perriard, 2009
|
Switzerland.
|
Yes
|
Yes
|
Yes
|
-
|
-
|
-
|
Yes
|
Layer of unfilled resin
|
Rinastiti, 2011
|
Indonesia
|
-
|
-
|
-
|
-
|
-
|
Self-Etching / Total-Etch
|
Yes
|
-
|
Ritter, 2020
|
USA
|
Yes
|
Yes
|
-
|
-
|
Yes
|
Universal
|
Yes
|
-
|
Saleh, 2020
|
Egypt
|
Yes
|
-
|
Yes
|
-
|
-
|
Total-ecth
|
-
|
Flowable composite/ Erbium-Yag Laser
|
Silva, 2015
|
Brazil
|
Yes
|
-
|
Yes
|
-
|
-
|
Self-Etching/ Conventional 3- Step
|
-
|
-
|
Soderholm, 1991
|
USA
|
-
|
-
|
Yes
|
-
|
-
|
Conventional 3-Step
|
-
|
Toluene
|
Sousa, 2013
|
Brazil
|
-
|
Yes
|
Yes
|
-
|
-
|
Conventional 3- Step / Conventional 2- Step
|
-
|
-
|
Staxrud, 2011
|
Norway
|
-
|
-
|
-
|
-
|
-
|
Conventional 2-Step
Self-Etching
|
-
|
-
|
Tantbirojn, 2015
|
USA
|
-
|
-
|
Yes
|
-
|
-
|
Conventional 2-Step
Universal
|
Yes
|
-
|
Valizadeh, 2020
|
Iran
|
Yes
|
Yes
|
Yes
|
-
|
-
|
Universal
|
-
|
Er,Cr:YSGG laser / Atmospheric plasma jet
|
Wiegand, 2012
|
Switzerland
|
Yes
|
Yes
|
-
|
Yes
|
Yes
|
Conventional 2-steps/ Self-Etching
|
Yes
|
-
|
Willers, 2021
|
Brazil
|
-
|
Yes
|
-
|
-
|
Yes
|
Conventional 3-Step/ Universal
|
|
|
Yap, 1999
|
Republic
of Singapore
|
-
|
Yes
|
-
|
-
|
-
|
Conventional 3-Step
|
-
|
Polyacrylic acid/ Maleic acid
|
Yarmohammadi, 2020
|
Iran
|
Yes
|
Yes
|
-
|
Yes
|
Yes
|
Universal
|
-
|
-
|
Zanatta, 2021
|
Brazil
|
Yes
|
Yes
|
-
|
-
|
-
|
Conventional 3-Step/ Self-Etching
|
-
|
-
|
Air abrasion was carried with the CoJet system in the majority of cases. This system consists of CoJet Prep, the intraoral microblasting unit; CoJet Sand, the coating medium for cold silicatisation of the restoration surface; ESPE Sil, the silane coupling agent (for silicated surfaces); Sinfony ™ Opaquer for masking exposed metal surfaces; Visio ™ Bond, the bonding agent for use with the restorative or veneering composite of the dentist’s choice. However, the studies did not use the complete system because the item Sinfony was not mentioned in any article, while the others were used in different combinations.
Meta-analyses
The analyses consisted of using a specific treatment (test group) or not (control group). When evaluating the use of air abrasion as a physical surface treatment, the general effect test for shear strength resulted in significant adhesion (p = 0.009. Figure 3a); this was the case for flexural strength (p = 0.003. Figure 3b). and for tensile strength (p = 0.004. Figure 4). With reference to the subgroup analyses, for the shear strength test, the surface treatment using the CoJet system with air abrasion, silane agent and adhesive (p = 0.0009. Figure 3a) resulted in statistical union, when compared with the total etching adhesive; using air abrasion before universal adhesive (p = 0.008. Figure 3a); air abrasion before a universal primer (p = 0.02. Figure 3a); in addition the use of air abrasion alone resulted in significant bonding (p < 0.00001. Figure 3a) when compared with the universal primer alone; in the same way, using air abrasion alone resulted in significant adhesion (p = 0.0006. Figure 3a) when compared with using argon plasma alone. Considering the flexural bond strength, air abrasion performed before the conventional 2-step adhesive bond was significant (p = 0.02. Figure 3b). Whereas in the tensile test it resulted in a static bond: air abrasion and CoJet system adhesive (p < 0.00001. Figure 4) compared with the conventional 2-step adhesive; the CoJet system with air abrasion, silane agent and adhesive (p = 0.002. Figure 4) compared with silane and universal adhesive; use of air abrasion after abrasive paper followed by universal adhesive (p = 0.008. Figure 4); and air abrasion of the CoJet system before phosphoric acid and unfilled resin resulted in statistical union (p = 0.03 Fig. 4). In the interfacial fracture toughness test, it resulted in statistical adhesion to air abrasion with CoJet system, diamond bur, silane and adhesive system (p < 0.0001) when compared with air abrasion, diamond bur and universal adhesive.
The diamond bur, another physical surface treatment used, resulted in a statistical union in the general effect obtained for the shear strength test (p = 0.02. Figure 5). Among its subgroups, the use of diamond bur (coarse grained) was significant (p = 0.007. Figure 5); also significant was the use of only the diamond bur and universal adhesive (p = 0.004. Figure 5) when compared with using only laser. Relative to the tensile strength test, the diamond bur (extrafine grained) (p = 0.008) resulted in statistical adhesion, followed by phosphoric acid, silane agent and universal adhesive; and so did the fine diamond bur (p = 0.005) when compared with super fine grained when it was followed by phosphoric acid and universal adhesive. Whereas, differently from these results, the diamond bur was negative when compared with air abrasion, which showed statistical adhesion (p = 0.001) when associated with phosphoric acid and universal adhesive; this was similar to air abrasion only (p < 0.0001) when compared with using only the diamond bur.
With reference to chemical surface treatments, the silane agent showed no improvement in adhesion, in which no overall effect of the tests was significant. Only some subgroups showed significant bonding, such as: for the flexural bond strength test, using silane agent before the universal adhesive (p = 0.004). In the tensile strength test, silane (p = 0.0001) associated with diamond bur, phosphoric acid and conventional 2-step adhesive. However, in the shear strength test, the control group resulted in significant adhesion, such as: the use of the total conditioning adhesive (p = 0.006) compared to the addition of silane; this also occurred with air abrasion and conventional 3-step adhesive (p = 0.00001) when compared with the test group that included the silanization step.
Another chemical treatment was the use of adhesive, in which no differences were found in the general effect, but some evaluations of subgroups showed statistical union, such as: in tensile strength, the conventional 3-step adhesive (p < 0.00001) when compared with that of 2 steps; this also occurred with the conventional 3-step adhesive (p = 0.002) when compared with the self-etching adhesive, after using a diamond bur; and the conventional 3-step adhesive (p = 0.04) compared with the universal adhesive, used after sandblasting with aluminum oxide and silane agent. In the flexural bond strength test, the use of universal adhesive (p < 0.00001) in comparison with the conventional 3-step adhesive, both previously etched with phosphoric acid.
In addition to these bonding treatments, chemical surface treatment with acids was also shown to aid adhesion. In the tensile strength test, phosphoric acid had no general effect (p < 0.00001. Figure 5b), and in its subgroups phosphoric acid 35% showed significant union (p < 0.00001. Figure 5b) associated with diamond bur and universal adhesive; this also occurred with phosphoric acid (p < 0.0003. Figure 5b) associated with a diamond bur, silane and universal adhesive. In the shear strength test, 10% hydrofluoric acid before the conventional adhesive resulted in statistical adhesion (p = 0.002) compared with the use of phosphoric acid. The figures relative to the other analysis are shown in the supplementary material, see online resource.
Risk of bias of the studies included
According to the parameters considered in the risk of bias analysis, the studies included in this review showed a high risk, most frequently for the blinding criteria relative to the evaluation of results, in which only two studies reported blinding. For the other criteria, generation of random sequence, incomplete data for results, selective report, variation coefficient and other biases, over 50% of the articles presented a low risk of bias, as shown in Fig. 2.