Adhesive bonding to dentin in aging and diabetes: a scoping review of substrate-related changes and bonding outcomes

Aging and diabetes mellitus are associated with structural and biochemical changes in dentin, including altered collagen organization, dentinal sclerosis, tubule occlusion, mineral changes, and, in some contexts, increased non-enzymatic collagen glycation. These substrate changes may influence the performance and durability of adhesive restorative materials. However, the extent to which bonding outcomes can be directly attributed to advanced glycation end products (AGEs) remains uncertain, as AGE levels are rarely measured in adhesive studies.

This scoping review followed the Joanna Briggs Institute methodology and was reported in accordance with the PRISMA-ScR guidelines. PubMed, Scopus, Web of Science, and Embase databases were searched from inception to December 1, 2025. Eligible studies evaluated bond strength, interfacial morphology, microleakage, mineral content, or remineralization in dentin affected by aging, diabetes, or experimental glycation. Study selection and data charting were independently conducted by two reviewers.

Of the 2615 records identified, 16 primary experimental studies met the inclusion criteria, most of which were in vitro investigations using extracted human teeth. Fifteen studies reported bond strength outcomes, and two assessed microleakage. Only four of the included studies directly evaluated diabetic dentin, and these studies generally reported reduced bond strength, particularly in type 1 diabetes. Most of the included studies evaluated age-related dentin, and the findings were heterogeneous, with many contemporary adhesives showing minimal differences between young and aged dentin. None of the included studies directly quantified AGE levels in dentin before adhesive testing.

Dentin alterations associated with aging and diabetes may influence adhesive performance; however, the available evidence is heterogeneous and does not allow these effects to be directly attributed to AGE accumulation. Therefore, aging and diabetes should be interpreted as distinct dentin-modifying contexts rather than equivalent AGE-mediated substrates. Further studies incorporating biochemical assessment of dentin, participant-level clinical variables, and standardized durability testing are needed.

The protocol for this scoping review was registered on the Open Science Framework (OSF) on 16th January 2026 (https://doi.org/10.17605/OSF.IO/JWA6H).