# A Literature Review of Adhesive Systems in Density: Key Components and Their Clinical Applications
## 8 Conclusions  
Adhesive agents have advanced beyond technique simplicity, and their current progress is prompted by versatility. To aid decision making, general dentists ought to remain up-to-the-minute on the ever-changing adhesive agents. Adhesive dental agents are commonly classified into three categories: ER, SE, and UAs. ER adhesives are available in three-step and two-step varieties, whilst SE adhesives are available in two-step and one-step versions. The pH of SE adhesives has a considerable effect on their bonding ability. UAs provide versatility by allowing dentists to choose an application method (ER, SE, or selective-etch) dependent on the substrate and clinical scenario. ER adhesives generally have high bond effectiveness. They still demand cautious technique and may be sensitive to dentin moisture levels. SE adhesives are popular among clinicians due to their superior efficiency and lessened method sensitivity. UAs offer an array of benefits of both processes, combining the advantages of ER and SE adhesives. However, the efficiency of UAs on dental hard tissues and indirect restorative materials is material dependent, as some adhesives are not intended to adhere to all types of restorative materials.  
Recognizing each category's features and limitations is crucial for successful bonding and dental restorations. Ongoing adhesive research and enhanced performance will help to advance the field of adhesive dentistry. As a result, practitioners need to stay up-to-date.  
Companies have been making continuing progress in the development of innovative dentin adhesives with the goal of easing the process and improving clinical outcomes, which correlates to their stability with time and BS efficiency. Even though simplicity of adhesive systems has been linked to a loss of effectiveness, efforts have been made to advance the chemistry of the latest adhesives.  
It is unclear if adhesives have reached a clinical performance level that can still be enhanced, particularly given the established higher efficiency of gold-standard adhesives. Perhaps clinicians are unaware that it has achieved a success rate exceeding 90% of what can be achieved with dental adhesion. To clinically differentiate adhesives in terms of bonding implementation, a substantially longer follow-up is now required to detect differences in their clinical outcomes across the most recent adhesive generations, even when compared to previous gold-standard multi-step adhesives. The new adhesive solutions can also be ascribed to their capacity to reduce or eliminate postoperative sensitivity, improve marginal seal, reduce microleakage, and increase resin flow into the fissure. The evolution of functional monomers with a strong and stable chemical affinity to HAp is unquestionably a beneficial direction in the pursuit of enhancing dentin adhesion.  
The challenge lies in the absence of a gold-standard approach for achieving stable and optimal adhesion of adhesive systems to dentin. Moreover, numerous researchers have proposed various methods to enhance BS. Importantly, the rationale behind this review was to achieve superior and long-lasting adhesion of resin composite to dental tissues, with a focus on developing cost-effective, user-friendly, and efficient adhesive systems.  
Conceptualization, R.B. and L.H.; methodology, R.B.; software, N.K.; validation, Y.H., C.E.C.-S. and R.B.; formal analysis, L.H.; investigation, R.B., Y.H. and M.L.-S.; resources, R.B.; data curation, R.B.; writing--original draft preparation, R.B.; writing--review and editing,Y.H., C.E.C.-S., N.K. and L.H.; visualization, M.L.-S., R.B. and L.H.; supervision, L.H., Y.H. and N.K.; project administration, L.H., Y.H. and N.K.; funding acquisition, R.B. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflicts of interest.