The shelf life of restoration mainly depends on the adhesion between the tooth and restorative material.^[1] Over the last few decades, numerous adhesive systems have been introduced to dentistry to create strong bonding to dentin and the restorative material. Dental adhesives are classified based on their generations or interaction with the smear layer.^[2] However, etch and rinse, self-etch, and universal adhesive systems are majorly considered for enhancing the adhesion of composite restorations to the tooth.^[3,4]

The adhesive seal may be compromised by the potential presence of any kind of residue (Powder from latex gloves, microbrush bristles, etc.).^[5] During the bonding process, dental surface contamination can occur after the tooth surface has been etched and/or after the adhesive system has been applied.^[6] As a result of contamination, the quality of the bond may be affected, causing micro leakage at the interface.^[7]

As per the author’s knowledge, the only study that has been conducted was by Berton et al.^[5] in which he evaluated the presence of microbrush bristles fiber remnants on the bonding surfaces of teeth. Thus, this paper aimed to determine the presence of microbrush bristle remnants on the bonding surface using total-etch and self-etch adhesive systems.

Ethics committee approval was taken before initiating the present study (Ref No. G-132/IECDYPDS/2023).

Recently, the complexity of restorative dentistry has increased with the variety of products being used.^[12] The use of composites and adhesives in modern restorative dentistry allows the creation of a stronger bonding of the restorative material with dental tissue (dentin and enamel).^[13] To achieve a long-lasting bonding between composites and the tooth tissues, numerous dental adhesive systems have been developed.^[14] However, present adhesion strategies depend exclusively on the way dental adhesives react with the smear layer.^[11]

In the present study, etch and rinse and self-etch dentin bonding systems were used. Irrespective of the adhesive systems used, microbrushes were used to apply the priming adhesive solution to determine a more unified micromechanical bonding. According to the study’s findings, the amount of microbrush remnants in the self-etch adhesive system was higher than in the total-etch adhesive system. This might be attributed to several reasons such as: different techniques of application of bonding agents on the tooth surface, the amount of force applied for the application, and the quality of the micro-brush being used. Moreover, SEM magnification for dental surfaces ranges between ×500 and ×5000, any remnant could have been missed, if detected as an artefact^[7,8] in the total-etch adhesive system group.

The etch and rinse adhesive method mainly relies on the etching of enamel and dentin with phosphoric acid to remove the smear layer along with its attached smear plugs. Bonding agent application is done over the tooth surface without the application of much force, as etching has been already done. However, self-etch adhesive systems do not employ a separate etching step as it does not remove the smear layer by their non-rinsing acidic primer. Instead, it integrates the smear layer residues into the adhesive interface.^[2] Results in our study showed a higher number of bristle remnants in the self-etch adhesive system as compared to the total-etch adhesive system, as an active adhesive application was used for the self-etch adhesive system. In this method, the microbrush was rubbed with slight force on the tooth surface.^[15] This could be one of the reasons for a higher number of bristle remnants in the Self-etch adhesive system due to enhanced force application and the stirring effect on the bonding surface.

The utilization of disposable microbrushes for the bonding agent application on the surfaces of teeth is broadly propagated.^[5] The utilization of microbrush during the insertion of fiber posts has been proven in the literature to create a more uniform micromechanical bond.^[16] Surprisingly, there is very scarce information regarding the effect of bristle remnants on the tooth surface. Thus, the present in vitro study found that after the standardized application of bonding agents, microbrushes left residues on the adhesive surface after employing different adhesive systems and techniques. These remaining fibers may have an impact on several variables, including forces of adhesion, integrity of marginal seal or development of microgaps in the bonding layer.^[5]

Nonetheless, additional research is required to evaluate the effects of these bristle remnants on the bonding surface of teeth and also to assess alternative methods for efficient bonding agent application that avoid contamination. Furthermore, the quality of the microbrush is to be considered when further studies will be conducted.

Irrespective of the adhesive systems used in the present study, the microbrush bristle remnants can be found over the tooth surface. Thus, the placement of composite restorations requires meticulous attention to procedure or it may fail prematurely.

However, dentists should be cautious to avoid contamination of the adhesive surface, as the presence of any remnants might influence the shelf life of restorations.