## 3 Results  
The latest search was performed on 9 November 2019. Figure 1 displays a flowchart representing the selection process of the studies involved in our work. Initially, 335 manuscripts were obtained (156 from PubMed and 179 from Scopus). Of those 335 studies, 147 were excluded as they were present in both databases. The title and abstract of each article were inspected, and 224 manuscripts were excluded because they were not relevant to the topic of this study or they did not meet the selection criteria (i.e., studies not related to dentistry or to dental restorations or based on macro-mechanical bonding tests; the latter were 29 studies). One study was excluded because the access to the manuscript was not possible, even after several attempts to contact the corresponding author [38]. A hand search was performed by checking the references in relevant papers, although no additional studies were found. Ten studies were included in the analysis, and their full texts were carefully examined. Among the studies selected, nine were published in English and one in Portuguese. Eight studies assessed \(\mu\)TBS, and two assessed \(\mu\)SBS. Only two studies were performed using bovine teeth, while the other eight studies were performed using human teeth (one used the primary molar, and seven used the third molar). Five studies used only a eugenol-based material as a control group, whereas the other five also had a non-eugenol-based material group as a control. The adhesive systems tested in the studies were Adper Single Bond 2 (3M ESPE, Saint Paul, MN, USA) and Optibond FL (Kerr, Orange, CA, USA); the SE adhesive systems were Clearfil SE Bond (Kuraray, Okayama, Japan), iBond (Heraeus Kulzer, Hanau, Germany), One-Up Bond F (Tokuyama, Tokyo, Japan), Adper SE Plus (3M ESPE, St Paul, MN, USA), and Adper Prompt (3M ESPE, Saint Paul, MN, USA). The descriptive data of the 10 included studies are shown in Table 1.  
Figure 1: Systematic review flow chart of studies comparing the bond strength of adhesive systems/composite resin to coronal dentin after contact with eugenol-based materials and without contact. \begin{table}
\begin{tabular}{c} [PERSON] et al. \begin{table}
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**Author** & **Methodology** & **Substrate** & **Adhesive** & **Legend Material** & **Legend Contact Time** & **Storage Time** & **Group** & **Bond Strength** & **SD** \\ \hline  & & & & & & & & & & \\ \cline{5-10}  & & & & & & & & & & & \\ \cline{5-10}  & & & & & & & & & & & \\ \cline{5-10}  & & & & & & & & & & \\ \cline{5-10}  & & & & & & & & & & \\ \cline{5-10}  & & & & & & & & & & \\ \cline{  
\begin{table}
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The provisional eugenol-based materials used were Provy (Herpo/Dentsply, Sao Paulo, Brazil), IRM (Dentsply, Milford, USA), TempCem (Vigodent, Rio de Janeiro, Brazil), TempBond (Kerr, Orange, CA, USA), and ZOE and eugenol (Biodinamica, Ibpora, Brazil and Maquira, Maringa, Brazil). The provisional non-eugenol-based materials were Dycal (Dentsply/Caulk, Milfort, DE, USA), TempCem NE (Vigodent, Rio de Janeiro, Brazil), Freegenol (GC, Kasugai, Japan), iodoform-based Guedes-Pinto paste (Biodinamica, Ibpora, Brazil; Maquira, Maringa, Brazil; Formula&Acao, compounding pharmacy, Sao Paulo, Brazil), and calcium hydroxide paste thickened with ZOE (S. S. White Artigos Dentarios Ltd.a., Rio de Janeiro, RJ, Brazil and Biodinamica, Ibpora, Brazil). In several studies, the effect of different eugenol contact times was tested, being the bond strength normally tested 24 h after the bonding step. In all studies, the primary outcome was bond strength expressed in MPa. The lowest mean for bond strength was 6.6 MPa, and the highest was 63 MPa (Table 1). During the qualitative analysis (Table 2), three studies were classified as having a high individual risk of bias, six as having a moderate individual risk of bias, and one as having a low individual risk of bias. The funnel plot (Figure 2) indicates the asymmetry among the studies.