Resin composite is one of the most frequently used direct restorative materials in clinical practice due the combination of favorable mechanical properties and excellent optical properties that mimic the tooth structure. However, resin composites have limitations related to long-term degradation and polymerization shrinkage, which influences the restoration longevity and often result in a repetitive restorative cycle [1]. In cases where the imperfections of a composite restoration are minor, such as a slight loss of anatomical shape or external discoloration, it might not be necessary to entirely replace the restoration. The repair technique, however, may also serve as an alternative procedure to address these minor issues [2,3].

Resin composite repairs are conservative procedures in which only the defective part of the composite is removed, followed by surface preparation and placement small resin composite increments. Among the advantages of this technique are lower cost, reduced clinical time, and preservation of dental tissue, decreasing the risk of pulp irritation [4], [5], [6]. Hence, the repair of resin composite restorations aligns with the principles of minimal intervention that presently steer dental practices [7]. Higher acceptance rate of repair procedures among patients has also been reported, due to reduced anxiety as anesthetic techniques are often unnecessary [8].

For the successful repair of a restoration, proper surface treatment is essential to ensure a strong and long-lasting bond between the old and the new resin composite increments. Achieving adhesion to older composites can be challenging, because of the material's degradation related to water sorption and a decreased count of unsaturated double bonds capable of reacting with the resin composite used in the repair [9,10]. The literature offers a diverse range of repair protocols, each with its own set of techniques and approaches. These protocols may encompass actions such as roughening the substrate surface using diamond burs or employing alumina blasting with aluminum oxide (Al2O3) to establish micromechanical retention. Additionally, there is a need for some chemical bond to bolster the bond strength of those repairs [6,[11], [12], [13]]. One approach involves the application of a silane coupling agent to enhance the bonding between the fillers and the organic resin matrix. Moreover, adhesive resins can be used to enhance the wetting properties of the mechanically treated and silanized surface [14], [15], [16], [17], [18], [19].

Numerous laboratory investigations have been undertaken to investigate the most reliable and durable bonding protocol for resin composite restoration repair. Nevertheless, a consensus has not yet emerged within the literature. While certain studies propose a combination of chemical surface treatments (silane and adhesives) with mechanical techniques (diamond bur roughening, aluminum oxide blasting, Er:YAG laser ablation) for restoration repair [20,21], others opt solely for the surface mechanical treatment [22,23]. Therefore, it is important to collect the current scientific evidence on surface treatments used in resin composite repair to provide guidance to dentists in their clinical practice. In light of this, the objective of this scoping review is to assess the available evidence concerning the various types of surface treatments employed in resin composite repair and their effects on the short- and long-term bond strength of the composite materials.